Receiving apparatus and receiving method

Abstract

A receiving device and a receiving method are provided. The receiving device includes: a receiving unit that receives a multiplexed signal; a first demapping unit that generates a first bit likelihood stream of a first data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a second modulated symbol stream of a second data sequence as an undetermined signal component; a second demapping unit that generates a second bit likelihood stream of a second data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a first modulated symbol stream of the first data sequence as an undetermined signal component; a first decoding unit that derives the first data sequence by performing error control decoding on the first bit likelihood stream; and a second decoding unit that derives the second data sequence by performing error control decoding on the second bit likelihood stream. The receiving unit receives a multiplexed signal in which a first modulated symbol stream and a second modulated symbol stream that is given a transformation corresponding to the first modulated symbol stream only in a first direction are superimposed.

Description

[0001] This application is a divisional application of the patent application with the Chinese Patent Application No. 201780048309.X (International Application No. PCT / JP2017 / 027832), filed on August 1, 2017, and titled "Receiving Apparatus and Receiving Method". Technical Field

[0002] The present disclosure relates to a receiving apparatus that receives a multiplexed signal and derives a plurality of data sequences from the multiplexed signal, and the like. Background Art

[0003] As a multiplexing method for multiplexing a plurality of data sequences for transmission, a multiplexing method using superposition coding (Non-Patent Document 1) is known. As other multiplexing methods, time division multiplexing (TDM) and frequency division multiplexing (FDM) are known (Non-Patent Document 2).

[0004] The multiplexing method using superposition coding is suitable for multiplexing a plurality of data sequences having different noise tolerances (reception tolerances) as compared with time division multiplexing and frequency division multiplexing. The multiplexing method using superposition coding is also known by the name of layer division multiplexing. In addition, the multiplexing method using superposition coding is also known as non-orthogonal multiple access (NOMA) applied to multiple access.

[0005] In the multiplexing method using superposition coding, a transmitting apparatus superimposes and transmits a plurality of modulation symbols obtained by respectively modulating a plurality of data sequences according to a predetermined power distribution. The receiving apparatus demodulates the plurality of modulation symbols multiplexed by superposition coding in order from the modulation symbol of the layer with high noise tolerance until the demodulation of the modulation symbol of the layer to which the desired data sequence belongs is completed.

[0006] Specifically, the receiving apparatus demodulates the modulation symbol of the layer with the highest noise tolerance to estimate the data sequence. Then, when the desired data sequence is not estimated, the receiving apparatus generates a replica of the modulation symbol based on the other estimated data sequences, cancels the replica from the received signal, and demodulates the modulation symbol of the layer with the second highest noise tolerance to estimate a new data sequence. The receiving apparatus repeats these processes until the desired data sequence is estimated.

[0007] Prior Art Documents

[0008] Non-Patent Literature

[0009] Non-Patent Literature 1: Seokhyun YOON and Donghee KIM, Performance of Superposition Coded Broadcast / Unicast Service Overlay System, IEICE Transactions on Communications, vol.E91-B, No.9

[0010] Non-Patent Literature 2: Thomas M. Cover, Broadcast Channels, IEEE Transactions on Information Theory, vol.IT-18, No.1

[0011] Non-Patent Literature 3: J. Zoellner and N. Loghin, Optimization of High-order Non-uniform QAM Constellations, IEEE International Symposium on Broadband Multimedia Systems and Broadcasting 2013 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] In a multiplexing method using superposition coding, sometimes the processing related to a plurality of data sequences is not performed efficiently.

[0014] For example, in a multiplexing method using superposition coding, due to the processing of sequentially decoding a plurality of multiplexed data sequences, a processing delay is generated. In addition, in a multiplexing method using superposition coding, it is necessary to make the receiving device have arithmetic resources for re-modulating the data sequence decoded first, etc. In addition, it is necessary to make the receiving device have memory resources for holding received symbols for decoding the next data sequence until the previous data sequence is decoded and re-modulated to obtain the modulated symbol stream of the previous data sequence, etc.

[0015] In addition, in a multiplexing method using superposition coding, the plurality of superimposed data sequences affect each other, and thus the transmission capacity may be reduced.

[0016] One example of an embodiment of the present disclosure solves the above problems in the multiplexing method using superimposed coding. However, the present disclosure also provides a method that solves only a part of the above problems or a method that solves a problem different from the above problems.

[0017] Solution for solving problems

[0018] A receiving device in one aspect of the present disclosure receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superimposed coding, and derives the plurality of data sequences from the multiplexed signal. The receiving device includes: a receiving unit that receives the multiplexed signal; a first demapping unit that generates a first likelihood stream of the first data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a second modulation symbol stream of the second data sequence as an undetermined signal component; a second demapping unit that generates a second likelihood stream of the second data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a first modulation symbol stream of the first data sequence as an undetermined signal component; a first decoding unit that derives the first data sequence by performing error control decoding on the first likelihood stream; and a second decoding unit that derives the second data sequence by performing error control decoding on the second likelihood stream. The receiving unit receives the multiplexed signal in which the first modulation symbol stream generated by mapping the first bit stream of the first data sequence and the second modulation symbol stream generated by mapping the second bit stream of the second data sequence are superimposed at a predetermined amplitude ratio. The second modulation symbol stream is given a transformation corresponding to the first modulation symbol stream only in a first direction among mutually perpendicular first and second directions in the complex plane representing the first modulation symbol stream and the second modulation symbol stream.

[0019] A receiving method in one aspect of the present disclosure receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superposition coding, and derives the plurality of data sequences from the multiplexed signal. In the receiving method, the multiplexed signal is received. In a state where the multiplexed signal includes a second modulation symbol stream of the second data sequence as an undetermined signal component, a first likelihood stream of the first data sequence is generated by demapping the multiplexed signal. In a state where the multiplexed signal includes a first modulation symbol stream of the first data sequence as an undetermined signal component, a second likelihood stream of the second data sequence is generated by demapping the multiplexed signal. The first data sequence is derived by performing error control decoding on the first likelihood stream. The second data sequence is derived by performing error control decoding on the second likelihood stream. In the reception of the multiplexed signal, the multiplexed signal in which the first modulation symbol stream generated by mapping a first bit stream of the first data sequence and the second modulation symbol stream generated by mapping a second bit stream of the second data sequence are superimposed at a prescribed amplitude ratio is received. The second modulation symbol stream is given a transformation corresponding to the first modulation symbol stream only in a first direction among mutually perpendicular first and second directions in a complex plane representing the first modulation symbol stream and the second modulation symbol stream.

[0020] Furthermore, these general or specific aspects can be implemented by using a system, apparatus, method, integrated circuit, computer program, or non-transitory recording medium such as a computer-readable CD-ROM, or can be implemented by using any combination of a system, apparatus, method, integrated circuit, computer program, and recording medium.

[0021] Advantageous Effects of the Invention

[0022] A receiving apparatus and the like in one aspect of the present disclosure can perform efficient processing with respect to a multiplexing method using superposition coding.

[0023] Further advantages and effects in one aspect of the present disclosure will become clearer based on the specification and the drawings. These advantages and effects are provided by the features described in the specification and the drawings, but it is also possible to provide a part of these advantages and effects by a part of the features described in the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a block diagram showing a structural example of a transmission apparatus in Embodiment 1.

[0025] Figure 2It is a block diagram showing a structural example of the receiving device in Embodiment 1.

[0026] Figure 3 It is a graph showing the transmission capacity based on superimposed coding.

[0027] Figure 4 It is a graph showing an example of the constellation of QPSK.

[0028] Figure 5 It is a graph showing an example of a non-uniform constellation.

[0029] Figure 6 It is a graph showing the transmission capacity based on superimposed coding using QPSK and Nu-256QAM.

[0030] Figure 7 It is a block diagram showing a first structural example of the receiving device in Embodiment 2.

[0031] Figure 8 It is a graph showing an example of a superimposed constellation.

[0032] Figure 9 It is a flowchart showing a first example of the receiving operation in Embodiment 2.

[0033] Figure 10 It is a graph showing an example of the simulation results for comparing successive decoding and parallel decoding in superimposed coding.

[0034] Figure 11 It is a block diagram showing a second structural example of the receiving device in Embodiment 2.

[0035] Figure 12 It is a flowchart showing a second example of the receiving operation in Embodiment 2.

[0036] Figure 13 It is a block diagram showing a first structural example of the transmitting device in Embodiment 3.

[0037] Figure 14 It is a block diagram showing a second structural example of the transmitting device in Embodiment 3.

[0038] Figure 15 It is a block diagram showing a third structural example of the transmitting device in Embodiment 3.

[0039] Figure 16 It is a block diagram showing a first structural example of the receiving device in Embodiment 3.

[0040] Figure 17 It is a block diagram showing a second structural example of the receiving device in Embodiment 3.

[0041] Figure 18It is a block diagram showing a third structural example of the receiving device in Embodiment 3.

[0042] Figure 19 It is a block diagram showing a fourth structural example of the receiving device in Embodiment 3.

[0043] Figure 20 It is a diagram showing an example of the deformed superposition constellation in Embodiment 3.

[0044] Figure 21 It is a flowchart showing an example of the transmission operation in Embodiment 3.

[0045] Figure 22 It is a flowchart showing an example of the reception operation in Embodiment 3.

[0046] Figure 23 It is a diagram showing an example of the simulation results for comparing successive decoding and parallel decoding in deformed superposition coding.

[0047] Figure 24 It is a block diagram showing a first structural example of the transmitting device in Embodiment 4.

[0048] Figure 25 It is a block diagram showing a second structural example of the transmitting device in Embodiment 4.

[0049] Figure 26 It is a block diagram showing a third structural example of the transmitting device in Embodiment 4.

[0050] Figure 27 It is a block diagram showing a first structural example of the receiving device in Embodiment 4.

[0051] Figure 28 It is a block diagram showing a second structural example of the receiving device in Embodiment 4.

[0052] Figure 29 It is a block diagram showing a third structural example of the receiving device in Embodiment 4.

[0053] Figure 30 It is a block diagram showing a fourth structural example of the receiving device in Embodiment 4.

[0054] Figure 31 It is a diagram showing an example of the BPSK constellation.

[0055] Figure 32 It is a diagram showing a first example of the deformed superposition constellation in Embodiment 4.

[0056] Figure 33 It is a flowchart showing an example of the transmission operation in Embodiment 4.

[0057] Figure 34It is a flowchart showing an example of a reception operation in Embodiment 4.

[0058] Figure 35 It is a diagram showing an example of a PAM-based constellation.

[0059] Figure 36 It is a diagram showing a second example of a deformed superposition constellation in Embodiment 4. Detailed Embodiments

[0060] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, the embodiments described below are all general or specific examples. The numerical values, shapes, materials, structural elements, arrangement positions and connection methods of structural elements, steps, order of steps, etc. shown in the following embodiments are examples and do not limit the gist of the protection scope. In addition, structural elements in the following embodiments that are not described in the structural elements of the independent claims representing the most general concept are described as optional structural elements.

[0061] In addition, coding sometimes refers to error control coding. Error control coding is also called error correction coding. In addition, decoding sometimes refers to error control decoding. Error control decoding is also called error correction decoding or error correction. In addition, unknown sometimes refers to undetermined. In addition, transmission sometimes refers to sending.

[0062] (Embodiment 1)

[0063] In the present embodiment, a case where a plurality of data sequences are multiplexed into a plurality of layers by a multiplexing method using superposition coding and transmitted is described.

[0064] In a plurality of embodiments including the present embodiment, in order to simplify the description within a range that does not compromise generality, a case where two data sequences are multiplexed into two different layers and transmitted is taken as an example. However, the multiplexing method described in a plurality of embodiments including the present embodiment can also be applied to a case where three or more data sequences are multiplexed into three or more different layers and transmitted.

[0065] In addition, in a plurality of embodiments including the present embodiment, the first layer to which the first data sequence belongs is used as a layer with higher noise tolerance than the second layer to which the second data sequence belongs.

[0066] Figure 1 An example of the structure of a transmission device 100 that multiplexes two data sequences into two layers and transmits them using superposition coding is shown. Refer to Figure 1 to describe the structure and operation of the transmission device 100.

[0067] The transmitting device 100 includes an encoding unit 111, an interleaving unit 112, a mapping unit 113, a multiplication unit 114, an encoding unit 121, an interleaving unit 122, a mapping unit 123, a multiplication unit 124, an addition unit 130, and an RF unit (Radio Frequency unit) 140. Each structural element can be a dedicated or general-purpose circuit. The multiplication unit 114, the multiplication unit 124, and the addition unit 130 can also be collectively represented as a superposition unit. The RF unit 140 can also be represented as a transmitting unit. The RF unit 140 can also include an antenna.

[0068] The encoding unit 111 performs encoding on the input first data sequence based on the first error control coding method to generate a first bit stream. The interleaving unit 112 sorts the bit order of the first bit stream generated by the encoding unit 111 based on the first sorting rule. This sorting is also referred to as interleaving.

[0069] The mapping unit 113 performs mapping processing on the first bit stream sorted by the interleaving unit 112 according to the first mapping method (first modulation method) to generate a first modulated symbol stream composed of a plurality of first modulated symbols. In the mapping processing according to the first mapping method, the mapping unit 113 maps each bit group of the first bit stream with a value of the bit group to one of the plurality of signal points in the first constellation.

[0070] The encoding unit 121 performs encoding on the input second data sequence based on the second error control coding method to generate a second bit stream. The interleaving unit 122 sorts the bit order of the second bit stream generated by the encoding unit 121 based on the second sorting rule. This sorting is also referred to as interleaving.

[0071] The mapping unit 123 performs mapping processing on the second bit stream sorted by the interleaving unit 122 according to the second mapping method (second modulation method) to generate a second modulated symbol stream composed of a plurality of second modulated symbols. In the mapping processing according to the second mapping method, the mapping unit 123 maps each bit group of the second bit stream with a value of the bit group to one of the plurality of signal points in the second constellation.

[0072] When using PSK modulation such as BPSK and QPSK, or QAM modulation such as 16QAM and 64QAM as the mapping method, the modulated symbol can be represented by a complex number that can use, for example, a real number to represent the magnitude of the in-phase component and an imaginary number to represent the magnitude of the quadrature component. In addition, when using PAM modulation as the mapping method, the modulated symbol can be represented by a real number.

[0073] The multiplication unit 114 multiplies the first modulation symbol of the first modulation symbol stream by the first amplitude coefficient a. 1 The multiplication unit 124 multiplies the second modulation symbol of the second modulation symbol stream by the second amplitude coefficient a. 2 The addition unit 130 superimposes the first modulation symbol multiplied by the first amplitude coefficient a 1 and the second modulation symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulation symbol stream composed of a plurality of superimposed modulation symbols.

[0074] The RF unit 140 transmits the generated superimposed modulation symbol stream as a signal. Specifically, the RF unit 140 generates a radio frequency band signal based on the superimposed modulation symbol stream generated by the addition unit 130 as a signal corresponding to the superimposed modulation symbol stream, and transmits the radio frequency band signal from the antenna.

[0075] That is, the superimposing unit composed of the multiplication unit 114, the multiplication unit 124, and the addition unit 130 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio. Then, the RF unit 140 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulation symbol stream. Further, the specified amplitude ratio may be 1:1, or the multiplication process may be omitted.

[0076] Figure 2 An example of the structure of a receiving device 200 that receives a signal in which two data sequences are multiplexed into two layers using superimposed coding and performs successive decoding to be able to obtain (extract) one or both of the two multiplexed data sequences is shown. Refer to Figure 2 to describe the structure and operation of the receiving device 200.

[0077] The receiving device 200 includes an RF unit 230, a demapping unit 211, a deinterleaving unit 212, a decoding unit 213, an encoding unit 214, an interleaving unit 215, a mapping unit 216, a multiplication unit 217, a delay unit 218, a subtraction unit 219, a demapping unit 221, a deinterleaving unit 222, and a decoding unit 223. Each structural element may be a dedicated or general-purpose circuit.

[0078] The demapping unit 211, the deinterleaving unit 212, the decoding unit 213, the encoding unit 214, the interleaving unit 215, the mapping unit 216, the multiplication unit 217, the delay unit 218, the subtraction unit 219, the demapping unit 221, the deinterleaving unit 222, and the decoding unit 223 may also be collectively represented as a derivation unit. The RF unit 230 may also be represented as a receiving unit. The RF unit 230 may also include an antenna.

[0079] The receiving device 200 receives the multiplexed signal transmitted from the transmitting device 100 using an antenna and inputs it to the RF unit 230. That is, the RF unit 230 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 230 is also represented as a received signal, corresponding to a superimposed modulation symbol stream formed by multiplexing a first modulation symbol stream and a second modulation symbol stream. The RF unit 230 generates a baseband received signal based on the received signal in the radio frequency band.

[0080] The demapping unit 211 demaps the baseband received signal based on the first constellation of the first mapping method to generate a first bit likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0081] The deinterleaving unit 212 sorts the first bit likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also called deinterleaving. The decoding unit 213 performs a decoding process based on the first error control coding method using the first bit likelihood stream sorted by the deinterleaving unit 212, and outputs the decoding result as a first data sequence.

[0082] Here, the demapping unit 211 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise), and demaps it based on the first constellation of the first mapping method.

[0083] When only the first data sequence is the acquisition target, the receiving device 200 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 200 performs the following process to acquire the second data sequence.

[0084] The encoding unit 214 encodes the first data sequence obtained by the decoding unit 213 based on the first error control coding method to generate a first bit stream. The interleaving unit 215 sorts the bit order of the first bit stream generated by the encoding unit 214 based on the first sorting rule. This sorting is also called interleaving.

[0085] The mapping unit 216 performs a mapping process according to the first mapping method on the first bit stream sorted by the interleaving unit 215 to generate a first modulation symbol stream composed of a plurality of first modulation symbols. The multiplication unit 217 multiplies the first modulation symbol stream output by the mapping unit 216 by the first amplitude coefficient a. 1 .

[0086] The delay unit 218 delays the received signal output from the RF unit 230 during the period from when the baseband received signal is output from the RF unit 230 until the reproduced first modulated symbol stream is output from the multiplication unit 217.

[0087] The subtraction unit 219 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 217 from the received signal delayed by the delay unit 218. 1 Thus, the subtraction unit 219 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 219 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream.

[0088] The demapping unit 221 demaps the signal output from the subtraction unit 219 based on the second constellation of the second mapping method to generate a second likelihood stream. For example, the amplitude coefficient a is reflected in the second constellation used for demapping. 2 .

[0089] The deinterleaving unit 222 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also called deinterleaving. The decoding unit 223 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 222 and outputs the decoding result as a second data sequence.

[0090] Through the above, the receiving device 200 obtains both or one of the first data sequence and the second data sequence from the signal received by the antenna.

[0091] <Superposition coding>

[0092] Next, superposition coding will be described.

[0093] Using the signal power P s (W), the noise power P n (W), and the transmission bandwidth B (Hz), the transmission capacity C T (bit / s) is given by Equation 1 as the Shannon limit.

[0094] [Equation 1]

[0095]

[0096] The transmission capacity C (bit / s / Hz) per 1 Hz normalized by the transmission bandwidth is given by Equation 2.

[0097] [Equation 2]

[0098]

[0099] Hereinafter, the "transmission capacity per 1 Hz" will be simply referred to as the "transmission capacity".

[0100] In the superposition coding of the first data sequence and the second data sequence, the signal power P s1 (W) of the first layer corresponding to the first data sequence, the signal power P s2 (W) of the second layer corresponding to the second data sequence, and the overall signal power P s (W) satisfy P s = P s1 + P s2 .

[0101] When demodulating the first layer, the receiving device 200 regards the component of the modulation symbol of the second layer as an unknown component superimposed on the modulation symbol of the first layer, that is, noise. Therefore, the transmission capacity C 1 of the first layer is given by Equation 3.

[0102] [Equation 3]

[0103]

[0104] When the receiving device 200 demodulates the second layer, the component of the modulation symbol of the first layer has been removed from the received signal. Therefore, the transmission capacity C 2 of the second layer is given by Equation 4.

[0105] [Equation 4]

[0106]

[0107] The sum of the transmission capacity C 1 of the first layer and the transmission capacity C 2 of the second layer is consistent with the Shannon limit as shown in Equation 5.

[0108] [Equation 5]

[0109]

[0110] In this embodiment, the signal power P s1 of the first layer corresponding to the first data sequence is proportional to the square of the first amplitude coefficient a 1 , and the signal power P s2 of the second layer corresponding to the second data sequence is proportional to the square of the second amplitude coefficient a 2 . The allocation of the signal power of multiple layers is determined by the amplitude coefficients multiplied by the modulation symbols of each layer.

[0111] In Figure 3 shows the signal power P s1 of the first layer and the signal power Ps2 The ratio is P s1 : P s2 An example of the simulation results of the respective transmission capacities when = 2:1. In Figure 3 , the horizontal axis represents the signal power P in dB (decibels) s and the noise power P n ratio (SNR), and the vertical axis represents the transmission capacity. In Figure 3 , the dotted line represents the transmission capacity C of the first layer 1 , the dashed line represents the transmission capacity C of the second layer 2 , and the solid line represents the transmission capacity C of the first layer 1 and the total transmission capacity of the transmission capacity C of the second layer 2 .

[0112] In addition, SNR refers to the ratio of the signal power to the noise power, and is also called the signal-to-noise power ratio or the signal-to-noise ratio.

[0113] <Non-uniform constellation>

[0114] In the present embodiment, the transmitting device 100 can use any mapping method as the first mapping method and the second mapping method, respectively. The receiving device 200 demodulates the first layer in a state where the second modulation symbol of the second layer is unknown. Therefore, as the first mapping method, a mapping method such as QPSK mainly for a low SNR is preferable.

[0115] Figure 4 An example of the constellation representing QPSK is shown. Specifically, in the complex plane where the horizontal axis is the real part (real component) and the vertical axis is the imaginary part (imaginary component), four signal points of QPSK are plotted. In QPSK, based on Figure 4 the constellation shown, a bit group (00, 01, 10, or 11) is associated with a complex modulation symbol.

[0116] On the other hand, the second layer is demodulated in a state where the modulation symbol of the first layer has been removed. Therefore, the second mapping method can also be a mapping method using a multi-valued constellation for a high SNR.

[0117] In recent years, as a multi-valued constellation, a non-uniform constellation as described in Non-Patent Document 3 has attracted attention. Different from a uniform constellation composed of signal points arranged at uniform intervals such as conventional QAM, a non-uniform constellation is a constellation composed of signal points arranged at non-uniform intervals. A mapping method using a non-uniform constellation sometimes increases the transmission capacity compared to a mapping method using a uniform constellation.

[0118] Figure 5An example of a non-uniform constellation (Nu-256QAM) composed of 256 signal points is shown. In Figure 5 , on the complex plane where the horizontal axis represents the real part and the vertical axis represents the imaginary part, 256 signal points of the non-uniform constellation are plotted.

[0119] Next, an example in the case of using the QPSK shown in Figure 4 as the first mapping method and the Nu-256QAM shown in Figure 5 as the second mapping method in the multiplexing method using superposition coding will be described.

[0120] In Figure 6 , the signal power P of the first layer s1 and the signal power P of the second layer s2 are shown, and the ratio is P s1 : P s2 = 2:1. An example of the simulation results of the respective transmission capacities in this case is shown. In Figure 6 , the horizontal axis represents the ratio (SNR) of the signal power P s to the noise power P n in dB (decibels), and the vertical axis represents the transmission capacity. In Figure 6 , the dotted line represents the transmission capacity C of the first layer 1 , and the dashed line represents the transmission capacity C of the second layer 2 . By combining QPSK and Nu-256QAM, a transmission capacity close to the limit shown in Figure 3 is obtained.

[0121] As described above, according to the present embodiment, the transmission device 100 can efficiently multiplex and transmit multiple data sequences by using the multiplexing method of superposition coding. Moreover, the receiving device 200 can efficiently receive the multiplexed multiple data sequences by using the multiplexing method of superposition coding. And, the transmission device 100 and the receiving device 200 can use a non-uniform constellation to increase the transmission capacity.

[0122] In addition, sorting (interleaving and deinterleaving) suppresses the influence in the case where errors occur continuously. Also, sorting (interleaving and deinterleaving) controls the correspondence between the bits constituting the codeword of the error correction code and the modulation symbol and the bits constituting the modulation symbol. However, sorting (interleaving and deinterleaving) can be omitted.

[0123] That is, the interleaving unit 112 and the interleaving unit 122 are optional structural elements and may not be included in the transmission device 100. Similarly, the deinterleaving unit 212, the interleaving unit 215, and the deinterleaving unit 222 are optional structural elements and may not be included in the receiving device 200.

[0124] However, interleaving and deinterleaving form a pair. Thus, basically, when the transmitting device 100 includes an interleaving section 112 and an interleaving section 122, the receiving device 200 includes a deinterleaving section 212, an interleaving section 215, and a deinterleaving section 222. On the other hand, when the transmitting device 100 does not include the interleaving section 112 and the interleaving section 122, the receiving device 200 does not include the deinterleaving section 212, the interleaving section 215, and the deinterleaving section 222.

[0125] In addition, the amplitude coefficient a may be reflected in the mapping in the mapping section 216 of the receiving device 200. 1 In this case, in the receiving device 200, the multiplication process may be omitted, and the receiving device 200 may not include a multiplication section 217.

[0126] In addition, the error control coding of the first data sequence and the second data sequence may be performed by an external device different from the transmitting device 100. In this case, in the transmitting device 100, the error control coding may be omitted. Moreover, the transmitting device 100 may not include an encoding section 111 and an encoding section 121.

[0127] (Embodiment 2)

[0128] <Parallel Decoding of Signals Obtained by Superposition Coding>

[0129] In the present embodiment, a receiving method for parallel decoding of signals obtained by superposition coding will be described. The structure of the transmitting device is the same as that of the transmitting device 100 shown in Figure 1 , and thus the description thereof will be omitted. In the parallel decoding in superposition coding, the receiving device does not remove the component of the modulated symbol stream of the first layer included in the received signal, treats the component of the modulated symbol stream of the first layer as an unknown signal (noise), and decodes the second layer.

[0130] Figure 7 FIG. shows an example of the structure of a receiving device 300 that receives a signal obtained by multiplexing two data sequences into two layers using superposition coding and performs parallel decoding to be able to obtain both or one of the two multiplexed data sequences. Referring to Figure 7 the structure and operation of the receiving device 300 will be described.

[0131] The receiving device 300 includes an RF section 330, a demapping section 310, a deinterleaving section 312, a decoding section 313, a deinterleaving section 322, and a decoding section 323. Each structural element may be a dedicated or general-purpose circuit. The demapping section 310, the deinterleaving section 312, the decoding section 313, the deinterleaving section 322, and the decoding section 323 may also be collectively represented as a derivation section. The RF section 330 may also be represented as a receiving section. The RF section 330 may also include an antenna.

[0132] The receiving device 300 receives the multiplexed signal transmitted from the transmitting device 100 using an antenna and inputs it to the RF unit 330. That is, the RF unit 330 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 330 is also represented as a received signal. The RF unit 330 generates a baseband received signal based on the received signal in the radio frequency band.

[0133] The demapping unit 310 demaps the baseband received signal to generate a first likelihood stream and a second likelihood stream. The demapping unit 310 demaps, for example, based on a superposition constellation representing the configuration of signal points of a superposition modulation symbol obtained by superimposing a first modulation symbol and a second modulation symbol using superposition coding.

[0134] The superposition constellation is determined according to a first constellation of a first mapping method, a second constellation of a second mapping method, a first amplitude coefficient a 1 and a second amplitude coefficient a 2 and so on.

[0135] Figure 8 An example of the superposition constellation is shown. Specifically, Figure 4 the constellation of QPSK shown is combined with Figure 5 the constellation of Nu-256QAM shown. More specifically, according to the four signal points of the QPSK constellation, the constellation of Nu-256QAM (256 signal points) is arranged in each of the four regions in the complex plane. These four regions corresponding to the constellation of Nu-256QAM may also partially overlap.

[0136] The demapping unit 310 demaps based on the superposition constellation as shown in Figure 8 That is, the demapping unit 310 generates a first likelihood stream in a state where the modulation symbol stream of the second layer is unknown, and generates a second likelihood stream in a state where the modulation symbol stream of the first layer is unknown.

[0137] In addition, the demapping unit 310 may use the first constellation of the first mapping method in the generation of the first likelihood stream and use the above superposition constellation in the generation of the second likelihood stream.

[0138] When the demapping unit 310 uses the first constellation in the generation of the first likelihood stream, compared with the case where the superposition constellation is also used in the generation of the first likelihood stream, the number of signal points considered in the generation of the first likelihood stream can be reduced. Therefore, in this case, the demapping unit 310 can reduce the amount of computation.

[0139] In addition, for example, the demapping unit 310 corresponds to: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal. The demapping unit 310 may also include: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal.

[0140] The deinterleaving unit 312 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 313 performs a decoding process based on the first error control coding method on the first likelihood stream sorted by the deinterleaving unit 312, and outputs the decoding result as a first data sequence.

[0141] The deinterleaving unit 322 sorts the second likelihood stream based on a sorting rule opposite to the second sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 323 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 322, and outputs the decoding result as a second data sequence.

[0142] In addition, similar to Embodiment 1, sorting (deinterleaving) may also be omitted. That is, the deinterleaving unit 312 and the deinterleaving unit 322 are optional structural elements and may not be included in the receiving device 300.

[0143] However, interleaving and deinterleaving form a pair. Thus, basically, when the transmitting device 100 includes the interleaving unit 112 and the interleaving unit 122, the receiving device 300 includes the deinterleaving unit 312 and the deinterleaving unit 322. On the other hand, when the transmitting device 100 does not include the interleaving unit 112 and the interleaving unit 122, the receiving device 300 does not include the deinterleaving unit 312 and the deinterleaving unit 322.

[0144] Figure 9 It is a flowchart showing an operation example of the receiving device 300. First, the RF unit 330 receives a multiplexed signal (S101) that is a signal in which a first data sequence and a second data sequence are multiplexed.

[0145] Next, the demapping unit 310 generates a first likelihood stream of the first data sequence by demapping the multiplexed signal (S102). In addition, the demapping unit 310 generates a second likelihood stream of the second data sequence by demapping the multiplexed signal (S103). The deinterleaving unit 312 may also deinterleave the generated first likelihood stream. In addition, the deinterleaving unit 322 may also deinterleave the generated second likelihood stream.

[0146] Then, the decoding unit 313 derives a first data sequence by performing error control decoding on the first likelihood stream (S104). Further, the decoding unit 323 derives a second data sequence by performing error control decoding on the second likelihood stream (S105).

[0147] In addition, basically, the processing of the first likelihood stream (generation, deinterleaving, and error control decoding) and the processing of the second likelihood stream (generation, deinterleaving, and error control decoding) are performed in parallel.

[0148] In Figure 7 the receiving apparatus 300 performing parallel decoding shown, compared with Figure 2 the receiving apparatus 200 performing successive decoding shown, the decoding performance of the second layer deteriorates.

[0149] In Figure 10 shows the signal power P s1 of the first layer and the signal power P s2 of the second layer, and the ratio is P s1 : P s2 = 2:1, an example of the simulation result of the transmission capacity of the second layer. In Figure 10 the horizontal axis represents the ratio (SNR) of the signal power P s to the noise power P n in dB (decibels), and the vertical axis represents the transmission capacity. In Figure 10 the solid line represents the transmission capacity of the second layer in the case of performing successive decoding, and the dashed line represents the transmission capacity of the second layer in the case of performing parallel decoding.

[0150] As Figure 10 shown, in the case of performing parallel decoding, compared with the case of performing successive decoding, in the decoding of the second layer, for the same transmission capacity, the required SNR increases, and for the same SNR, the transmission capacity decreases.

[0151] As described above, the receiving apparatus 300 performing parallel decoding in the present embodiment has deteriorated decoding performance related to the second data sequence transmitted in the second layer compared with the receiving apparatus 200 performing successive decoding. However, the structure required for decoding the second layer can be reduced.

[0152] Specifically, compared with Figure 2 the receiving apparatus 200 performing successive decoding shown, the receiving apparatus 300 does not require the encoding unit 214, deinterleaving unit 215, mapping unit 216, and multiplication unit 217 for reproducing the modulated symbol stream of the first layer. In addition, it does not require the delay unit 218 for delaying the received signal and the subtraction unit 219 for removing the component of the modulated symbol of the reproduced first layer from the received signal.

[0153] Therefore, the circuit scale can be reduced. In addition, the receiving device 300 can reduce the amount of computation compared to the receiving device 200, and can reduce the power consumption.

[0154] Moreover, Figure 2 The receiving device 200 performing successive decoding as shown demodulates the first layer of the received signal to obtain the first data sequence, generates the first modulated symbol stream based on the obtained first data sequence, and then starts demodulating the second layer of the received signal to obtain the second data sequence. On the other hand, the receiving device 300 performing parallel decoding in the present embodiment can execute the acquisition of the first data sequence and the acquisition of the second data sequence simultaneously in parallel, so that the processing delay can be shortened.

[0155] In addition, the receiving device may also observe the SNR of the received signal, and switch the decoding process in such a way that parallel decoding is performed when the SNR is high and successive decoding is performed when the SNR is low.

[0156] In this case, for example, Figure 2 The receiving device 200 as shown includes a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may be included in the RF unit 230 or the demapping unit 221. And the demapping unit 221 has a structure that performs, in addition to the demapping process based on the second constellation, the demapping process based on the superimposed constellation as described for the operation of the demapping unit 310. Figure 7

[0157] Then, the demapping unit 221 switches between the demapping process based on the second constellation for the signal output from the subtraction unit 219 and the demapping process based on the superimposed constellation for the signal output from the RF unit 230. For example, the demapping unit 221 switches these demapping processes according to the control signal from the control unit.

[0158] Figure 11 An example of the structure of the receiving device 400 that selectively performs parallel decoding and successive decoding is shown. The receiving device 400 includes an RF unit 430, a demapping unit 411, a deinterleaving unit 412, a decoding unit 413, an encoding unit 414, an interleaving unit 415, a mapping unit 416, a multiplication unit 417, a delay unit 418, a subtraction unit 419, a demapping unit 421, a deinterleaving unit 422, and a decoding unit 423. Figure 11 A plurality of structural elements of the receiving device 400 as shown are Figure 2 basically the same as a plurality of structural elements of the receiving device 200 as shown.

[0159] However, in addition to performing the demapping process of the second constellation based on the second mapping method, the demapping unit 421 of the receiving device 400 also performs the demapping process based on the superimposed constellation. For example, the demapping unit 421 switches the process of demapping the signal output from the subtraction unit 419 based on the second constellation and the process of demapping the signal output from the RF unit 430 based on the superimposed constellation according to the SNR.

[0160] In addition, in the Figure 11 example, the control unit for switching successive decoding and parallel decoding according to the SNR is omitted, but the control unit may also be included in the demapping unit 421, may also be included in the RF unit 430, and may also be included in the receiving device 400 as a new structural element.

[0161] Figure 12 is a flowchart showing an operation example of the receiving device 400. First, the RF unit 430 receives a multiplexed signal (S201), which is a signal obtained by multiplexing the first data sequence and the second data sequence. Then, the RF unit 430 determines whether the multiplexed signal satisfies a specified criterion. For example, the specified criterion means that the SNR is higher than a specified threshold.

[0162] Here, when the multiplexed signal satisfies the specified criterion ("Yes" in S202), the demapping unit 411 generates the first bit likelihood stream of the first data sequence by demapping the multiplexed signal (S203). In addition, the demapping unit 421 generates the second bit likelihood stream of the second data sequence by demapping the multiplexed signal (S204). The deinterleaving unit 412 may deinterleave the generated first bit likelihood stream. The deinterleaving unit 422 may deinterleave the generated second bit likelihood stream.

[0163] Then, the decoding unit 413 derives the first data sequence by performing error control decoding on the first bit likelihood stream (S205). In addition, the decoding unit 423 derives the second data sequence by performing error control decoding on the second bit likelihood stream (S206).

[0164] These operations (S203 to S206) are basically the same as the Figure 9 operations (S102 to S105) shown.

[0165] On the other hand, when the multiplexed signal does not satisfy the specified criterion ("No" in S202), the demapping unit 411 generates the first bit likelihood stream of the first data sequence by demapping the multiplexed signal (S207). The deinterleaving unit 412 may deinterleave the generated first bit likelihood stream. Then, the decoding unit 413 derives the first data sequence by performing error control decoding on the first bit likelihood stream (S208).

[0166] Next, the encoding unit 414 generates a first bit stream by performing error control encoding on the first data sequence (S209). The interleaving unit 415 may also interleave the generated first bit stream. Next, the mapping unit 416 generates a first modulated symbol stream by mapping the first bit stream (S210). The multiplication unit 417 may also multiply the first modulated symbol stream by the amplitude coefficient a 1 .

[0167] In addition, the delay unit 418 delays the multiplexed signal until the first modulated symbol stream is generated (S211). Then, the subtraction unit 419 subtracts the first modulated symbol stream from the multiplexed signal (S212).

[0168] Next, the demapping unit 421 generates a second likelihood stream by demapping the multiplexed signal from which the first modulated symbol stream has been subtracted (S213). The deinterleaving unit 422 may also deinterleave the generated second likelihood stream. Next, the decoding unit 423 performs error control decoding on the second likelihood stream to derive the second data sequence (S214).

[0169] Thus, in the case of high SNR, the receiving device 400 can reduce the amount of computation and power consumption by performing parallel decoding. In addition, in the case of high SNR, the receiving device 400 can shorten the processing delay by performing parallel decoding. On the other hand, in the case of low SNR, the possibility that the receiving device 400 can accurately decode the second data sequence by performing successive decoding becomes high.

[0170] In addition, basically, the first mapping method and the second mapping method in the present embodiment are the same as the first mapping method and the second mapping method in Embodiment 1. That is, basically, the first constellation and the second constellation in the present embodiment are the same as the first constellation and the second constellation in Embodiment 1. In the second mapping method, a uniform constellation or a non-uniform constellation may be used.

[0171] (Embodiment 3)

[0172] <Modified superposition coding (variant superposition coding)>

[0173] In the present embodiment, a method of multiplexing and transmitting a plurality of data sequences using modified superposition coding (variant superposition coding) obtained by modifying the above superposition coding is described.

[0174] Figure 13 An example of the structure of a transmitting device 500 that multiplexes two data sequences into two layers and transmits them using modified superposition coding is shown. Refer to Figure 13 to describe the structure and operation of the transmitting device 500.

[0175] The transmitting device 500 includes an encoding unit 511, an interleaving unit 512, a mapping unit 513, a multiplication unit 514, an encoding unit 521, an interleaving unit 522, a mapping unit 523, a transformation unit 525, a multiplication unit 524, an addition unit 530, and an RF unit 540. Each structural element may be a dedicated or general-purpose circuit. The multiplication unit 514, the multiplication unit 524, and the addition unit 530 may also be collectively represented as a superposition unit. The RF unit 540 may also be represented as a transmitting unit. The RF unit 540 may also include an antenna.

[0176] The encoding unit 511 encodes the input first data sequence based on a first error control coding method to generate a first bit stream. The interleaving unit 512 sorts the bit order of the first bit stream generated by the encoding unit 511 based on a first sorting rule. This sorting is also referred to as interleaving.

[0177] The mapping unit 513 performs a mapping process on the first bit stream sorted by the interleaving unit 512 according to a first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. In the mapping process according to the first mapping method, the mapping unit 513 maps the first bit stream in groups of the first number of bits to one of the plurality of signal points in the first constellation according to the value of the bit group.

[0178] When using PSK modulation such as BPSK and QPSK, or QAM modulation such as 16QAM and 64QAM as the first mapping method, the first modulation symbol can be represented by a complex number that can use, for example, a real number to represent the magnitude of the in-phase component and an imaginary number to represent the magnitude of the quadrature component. Additionally, when using PAM modulation as the first mapping method, the first modulation symbol can be represented by a real number.

[0179] The encoding unit 521 encodes the input second data sequence based on a second error control coding method to generate a second bit stream. The interleaving unit 522 sorts the bit order of the second bit stream generated by the encoding unit 521 based on a second sorting rule. This sorting is also referred to as interleaving.

[0180] The mapping unit 523 performs a mapping process on the second bit stream sorted by the interleaving unit 522 according to a second mapping method to generate a second modulation symbol stream composed of a plurality of second modulation symbols. In the mapping process according to the second mapping method, the mapping unit 523 maps the second bit stream in groups of the second number of bits to one of the plurality of signal points in the second constellation according to the value of the bit group.

[0181] When using PSK modulation such as BPSK and QPSK, or QAM modulation such as 16QAM and 64QAM as the second mapping method, the second modulation symbol can be represented by a complex number that uses, for example, a real number to represent the magnitude of the in-phase component and an imaginary number to represent the magnitude of the quadrature component. In addition, when using PAM modulation as the second mapping method, the second modulation symbol can be represented by a real number. In the second mapping method, either a uniform constellation or a non-uniform constellation can be used.

[0182] The transformation unit 525 performs a transformation on the second modulation symbol superimposed on the first modulation symbol based on the value of the bit used in the generation of the first modulation symbol. Thus, the transformation unit 525 performs a transformation on the second modulation symbol stream.

[0183] The multiplication unit 514 multiplies the first modulation symbol of the first modulation symbol stream by the first amplitude coefficient a 1 . The multiplication unit 524 multiplies the second modulation symbol of the second modulation symbol stream transformed by the transformation unit 525 by the second amplitude coefficient a 2 . The addition unit 530 superimposes the first modulation symbol multiplied by the first amplitude coefficient a 1 and the second modulation symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulation symbol stream composed of a plurality of superimposed modulation symbols.

[0184] The RF unit 540 transmits the generated superimposed modulation symbol stream as a signal. Specifically, the RF unit 540 generates a radio frequency band signal as a signal corresponding to the superimposed modulation symbol stream based on the superimposed modulation symbol stream generated by the addition unit 530, and transmits the radio frequency band signal from the antenna.

[0185] That is, the superimposing unit composed of the multiplication unit 514, the multiplication unit 524, and the addition unit 530 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio. Then, the RF unit 540 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulation symbol stream. Also, the specified amplitude ratio can be 1:1, or the multiplication process can be omitted.

[0186] The operation of the transformation unit 525 will be described by taking the case where QPSK is used as the first mapping method as an example.

[0187] For example, when S 1 (t) is the t-th modulation symbol of the first modulation symbol stream generated by the mapping unit 513, and b 1 (t) and b 2 (t) are the bits mapped to S 1 (t), the modulation symbol S is given by Equation 61 (t).

[0188] [Number 6]

[0189]

[0190] Here, i is the imaginary unit. The modulation symbol S can also be given by an expression in which the polarity (positive or negative) of either one or both of the real part and the imaginary part of Expression 6 is inverted. 1 (t). Bit b 1 (t) is the bit that contributes to the real part of the modulation symbol S 1 (t). Bit b 2 (t) is the bit that contributes to the imaginary part of the modulation symbol S 1 (t).

[0191] The transformation unit 525 transforms the t-th modulation symbol S 1 (t) and b 2 (t) of the second modulation symbol stream generated by the mapping unit 523 into S' 2 (t) according to Expression 7. 2 (t).

[0192] [Number 7]

[0193]

[0194] Here, S' 2 (t) is the t-th modulation symbol of the transformed second modulation symbol stream. In addition, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). The modulation symbol S' 2 (t) can also be given by an expression in which the polarity of either one or both of the real part and the imaginary part of Expression 7 is inverted.

[0195] As described above, in the deformed superposition coding, the polarities of the real part and the imaginary part of the second modulation symbol are controlled according to the value of the bit of the first modulation symbol mapped to be superimposed on the second modulation symbol. In addition, the polarities of the real part and the imaginary part of the second modulation symbol can also be controlled according to the first modulation symbol superimposed on the second modulation symbol. Further, either one or both of the polarities of the real part and the imaginary part of the second modulation symbol can be controlled.

[0196] Figure 14 An example of the structure of the transmission device 600 that multiplexes two data sequences into two layers using the deformed superposition coding for transmission is shown. The structure of the transmission device 600 is different from the structure of the transmission device 500. Refer to Figure 14To describe the structure and operation of the transmission device 600.

[0197] The transmission device 600 includes an encoding unit 611, an interleaving unit 612, a mapping unit 613, a multiplication unit 614, an encoding unit 621, an interleaving unit 622, a mapping unit 623, a transformation unit 625, a multiplication unit 624, an addition unit 630, and an RF unit 640. Each structural element can be a dedicated or general-purpose circuit. The multiplication unit 614, the multiplication unit 624, and the addition unit 630 can also be collectively represented as a superposition unit. The RF unit 640 can also be represented as a transmission unit. The RF unit 640 may also include an antenna.

[0198] The encoding unit 611 encodes the input first data sequence based on the first error control coding method to generate a first bit stream. The interleaving unit 612 sorts the bit order of the first bit stream generated by the encoding unit 611 based on the first sorting rule. This sorting is also referred to as interleaving.

[0199] The mapping unit 613 performs a mapping process on the first bit stream sorted by the interleaving unit 612 according to the first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. In the mapping process according to the first mapping method, the mapping unit 613 maps each bit group of the first bit stream according to the value of the bit group to one of the plurality of signal points in the first constellation.

[0200] The encoding unit 621 encodes the input second data sequence based on the second error control coding method to generate a second bit stream. The interleaving unit 622 sorts the bit order of the second bit stream generated by the encoding unit 621 based on the second sorting rule. This sorting is also referred to as interleaving.

[0201] The mapping unit 623 performs a mapping process on the second bit stream sorted by the interleaving unit 622 according to the second mapping method to generate a second modulation symbol stream composed of a plurality of second modulation symbols. In the mapping process according to the second mapping method, the mapping unit 623 maps each bit group of the second bit stream according to the value of the bit group to one of the plurality of signal points in the second constellation.

[0202] The transformation unit 625 performs a transformation on the second modulation symbol superimposed on the generated first modulation symbol based on the first modulation symbol. Thus, the transformation unit 625 performs a transformation on the second modulation symbol stream.

[0203] The multiplication unit 614 multiplies the first modulation symbol of the first modulation symbol stream by the first amplitude coefficient a 1 . The multiplication unit 624 multiplies the second modulation symbol of the second modulation symbol stream transformed by the transformation unit 625 by the second amplitude coefficient a 2 . The addition unit 630 adds the first modulation symbol stream multiplied by the first amplitude coefficient a 1The first modulation symbol is superimposed on the second modulation symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulation symbol stream composed of a plurality of superimposed modulation symbols.

[0204] The RF unit 640 transmits the generated superimposed modulation symbol stream as a signal. Specifically, the RF unit 640 generates a radio band signal as a signal corresponding to the superimposed modulation symbol stream based on the superimposed modulation symbol stream generated by the addition unit 630, and transmits the radio band signal from the antenna.

[0205] That is, the superimposing unit composed of the multiplication unit 614, the multiplication unit 624, and the addition unit 630 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio. Then, the RF unit 640 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulation symbol stream. Additionally, the specified amplitude ratio can be 1:1, and the multiplication process can also be omitted.

[0206] Taking the case where QPSK is used as the first mapping method as an example, the operation of the conversion unit 625 will be described.

[0207] For example, when S 1 (t) is the t-th modulation symbol of the first modulation symbol stream generated by the mapping unit 613, and b 1 (t) and b 2 (t) are the multiple bits mapped to S 1 (t), the modulation symbol S 1 (t) is given by Equation 8.

[0208] [Equation 8]

[0209]

[0210] Here, i is the imaginary unit. The modulation symbol S 1 (t) can also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 8 is reversed. The bit b 1 (t) is the bit that contributes to the real part of the modulation symbol S 1 (t). The bit b 2 (t) is the bit that contributes to the imaginary part of the modulation symbol S 1 (t).

[0211] The conversion unit 625 transforms the t-th modulation symbol S 1 (t) of the second modulation symbol stream generated by the mapping unit 623 into S' 2 (t) according to Equation 9 based on the modulation symbol S 2 (t).

[0212] [Number 9]

[0213]

[0214] Here, S’ 2 (t) is the t-th modulation symbol of the transformed second modulation symbol stream. Additionally, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). Additionally, sgn(Re[S 1 (t)]) is the polarity of the real part of S 1 (t), and sgn(Im[S 1 (t)]) is the polarity of the imaginary part of S 1 (t).

[0215] The modulation symbol S’ 2 (t) can also be given by an expression in which the polarity of one or both of the real part and the imaginary part of Equation 9 is inverted. In addition, the transformation based on Equation 9 is substantially the same as the transformation based on Equation 7.

[0216] As described above, in the deformed superposition coding, the polarities of the real part and the imaginary part of the second modulation symbol are controlled according to the first modulation symbol superimposed on the second modulation symbol. In addition, the polarities of the real part and the imaginary part of the second modulation symbol can also be controlled according to the value of the bit mapped to the first modulation symbol superimposed on the second modulation symbol. Additionally, either one or both of the polarities of the real part and the imaginary part of the second modulation symbol can be controlled.

[0217] Figure 15 FIG. 7 shows an example of the structure of a transmission device 700 that multiplexes two data sequences onto two layers and transmits them using deformed superposition coding. The structure of the transmission device 700 is different from the structures of the transmission devices 500 and 600. Refer to Figure 15 to describe the structure and operation of the transmission device 700.

[0218] The transmission device 700 includes an encoding unit 711, an interleaving unit 712, a mapping unit 713, a multiplication unit 714, an encoding unit 721, an interleaving unit 722, a mapping unit 723, a multiplication unit 724, an addition unit 730, and an RF unit 740. Each structural element can be a dedicated or general-purpose circuit. The multiplication unit 714, the multiplication unit 724, and the addition unit 730 can also be collectively represented as a superposition unit. The RF unit 740 can also be represented as a transmission unit. The RF unit 740 can also include an antenna. The mapping unit 723 can also include a transformation unit.

[0219] The encoding unit 711 performs encoding on the input first data sequence based on the first error control coding method to generate a first bit stream. The interleaving unit 712 sorts the bit order of the first bit stream generated by the encoding unit 711 based on the first sorting rule. This sorting is also referred to as interleaving.

[0220] The mapping unit 713 performs mapping processing on the first bit stream sorted by the interleaving unit 712 according to the first mapping method, and generates a first modulated symbol stream composed of a plurality of first modulated symbols. In the mapping processing according to the first mapping method, the mapping unit 713 maps each bit group of the first bit stream with a value of the bit group to a certain signal point among a plurality of signal points in the first constellation.

[0221] The encoding unit 721 performs encoding on the input second data sequence based on the second error control coding method to generate a second bit stream. The interleaving unit 722 sorts the bit order of the second bit stream generated by the encoding unit 721 based on the second sorting rule. This sorting is also referred to as interleaving.

[0222] The mapping unit 723 transforms (deforms) the second mapping method according to the first bit stream mapped to the first modulated symbol stream by the mapping unit 713. Then, the mapping unit 723 performs mapping processing on the second bit stream sorted by the interleaving unit 722 according to the second mapping method transformed according to the first bit stream. Thus, the mapping unit 723 generates a second modulated symbol stream composed of a plurality of second modulated symbols.

[0223] In the mapping processing according to the second mapping method, the mapping unit 723 maps each bit group of the second bit stream with a value of the bit group to a certain signal point among a plurality of signal points in the second constellation.

[0224] The multiplication unit 714 multiplies the first modulated symbol of the first modulated symbol stream by the first amplitude coefficient a 1 。The multiplication unit 724 multiplies the second modulated symbol of the second modulated symbol stream by the second amplitude coefficient a 2 。The addition unit 730 superimposes the first modulated symbol multiplied by the first amplitude coefficient a 1 and the second modulated symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulated symbol stream composed of a plurality of superimposed modulated symbols.

[0225] The RF unit 740 transmits the generated superimposed modulated symbol stream as a signal. Specifically, the RF unit 740 generates a radio frequency band signal based on the superimposed modulated symbol stream generated by the addition unit 730 as a signal corresponding to the superimposed modulated symbol stream, and transmits the radio frequency band signal from the antenna.

[0226] That is, the superposition unit composed of the multiplication unit 714, the multiplication unit 724, and the addition unit 730 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulated symbol stream and the second modulated symbol stream at a specified amplitude ratio. Then, the RF unit 740 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulated symbol stream. Further, the specified amplitude ratio may be 1:1, and the multiplication process may be omitted.

[0227] Taking the case where QPSK is used as the first mapping method as an example, the operation of the mapping unit 723 will be described.

[0228] For example, in S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 713, and b 1 (t) and b 2 (t) are the bits mapped to S 1 (t), the modulated symbol S 1 (t) is given by Equation 10.

[0229] [Equation 10]

[0230]

[0231] Here, i is the imaginary unit. The modulated symbol S 1 (t) may also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 10 is inverted. The bit b 1 (t) is the bit that contributes to the real part of the modulated symbol S 1 (t). The bit b 2 (t) is the bit that contributes to the imaginary part of the modulated symbol S 1 (t).

[0232] The mapping unit 723 performs an exclusive-OR operation on the bit b 1 (t) of the second bit stream input from the interleaving unit 722, which contributes most to the real part of the second constellation. In addition, the mapping unit 723 performs an exclusive-OR operation on the bit b 2 (t) of the second bit stream input from the interleaving unit 722, which contributes most to the imaginary part of the second constellation. Then, based on the second constellation, the second bit stream on which these exclusive-OR operations have been performed is mapped.

[0233] Here, the bit that contributes most to the real part of the second constellation refers to the bit whose polarity of the real part of the second constellation is inverted when the value of the bit is inverted from 0 to 1 or from 1 to 0. That is, the bit that contributes most to the real part of the second constellation refers to the bit whose sign of the positive and negative of the real part value in the modulated symbol is inverted when the value of the bit is inverted from 0 to 1 or from 1 to 0.

[0234] Similarly, the bit that contributes most to the imaginary part of the second constellation refers to the bit whose polarity of the imaginary part of the second constellation is reversed, for example, when the value of the bit is reversed from 0 to 1 or from 1 to 0. That is, the bit that contributes most to the imaginary part of the second constellation refers to the bit whose sign of the positive and negative values of the imaginary part in the modulation symbol is reversed, for example, when the value of the bit is reversed from 0 to 1 or from 1 to 0.

[0235] In the above, the mapping unit 723 substantially transforms the second mapping method (second constellation) by transforming the second bit stream. However, the mapping unit 723 may also directly transform the second mapping method (second constellation) without transforming the second bit stream. That is, the mapping unit 723 may also transform the correspondence between the bit group and the signal point in the second constellation.

[0236] In addition, the transformation performed by the mapping unit 723 may also be performed by a transformation unit included in the mapping unit 723.

[0237] As described above, in the deformed superposition coding, the polarities of the real part and the imaginary part of the second modulation symbol are controlled according to the value of the bit mapped to the first modulation symbol superimposed on the second modulation symbol. In addition, the polarities of the real part and the imaginary part of the second modulation symbol may also be controlled according to the first modulation symbol superimposed on the second modulation symbol. In addition, either one or both of the polarities of the real part and the imaginary part of the second modulation symbol may be controlled.

[0238] <Successive Decoding of Signals Obtained by Deformed Superposition Coding>

[0239] Figure 16 An example of the structure of a receiving device 800 that represents receiving a signal formed by multiplexing two data sequences into two layers using the above-described deformed superposition coding and performing successive decoding to be able to obtain one or both of the two multiplexed data sequences is shown. Refer to Figure 16 to describe the structure and operation of the receiving device 800.

[0240] The receiving device 800 includes an RF unit 830, a demapping unit 811, a deinterleaving unit 812, a decoding unit 813, an encoding unit 814, an interleaving unit 815, a mapping unit 816, a multiplication unit 817, a delay unit 818, a subtraction unit 819, a transformation unit 820, a demapping unit 821, a deinterleaving unit 822, and a decoding unit 823. Each structural element may be a dedicated or general-purpose circuit.

[0241] The demapping unit 811, the deinterleaving unit 812, the decoding unit 813, the encoding unit 814, the interleaving unit 815, the mapping unit 816, the multiplication unit 817, the delay unit 818, the subtraction unit 819, the transformation unit 820, the demapping unit 821, the deinterleaving unit 822, and the decoding unit 823 may also be collectively represented as a derivation unit. The RF unit 830 may also be represented as a receiving unit. The RF unit 830 may also include an antenna.

[0242] The receiving device 800 receives the multiplexed signal transmitted from the transmitting devices 500, 600, or 700 using an antenna and inputs it to the RF unit 830. That is, the RF unit 830 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 830 is also represented as a received signal, corresponding to the superimposed modulation symbol stream formed by multiplexing the first modulation symbol stream and the second modulation symbol stream. The RF unit 830 generates a baseband received signal based on the received signal in the radio frequency band.

[0243] The demapping unit 811 demaps the baseband received signal based on the first constellation of the first mapping method to generate a first likelihood stream. For example, the amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0244] The deinterleaving unit 812 sorts the first likelihood stream based on the sorting rule opposite to the first sorting rule. This sorting is also called deinterleaving. The decoding unit 813 performs decoding processing based on the first error control coding method using the first likelihood stream sorted by the deinterleaving unit 812 and outputs the decoding result as the first data sequence.

[0245] Here, the demapping unit 811 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise) and performs demapping based on the first constellation of the first mapping method.

[0246] When only the first data sequence is the acquisition target, the receiving device 800 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 800 performs the following process to acquire the second data sequence.

[0247] The encoding unit 814 encodes the first data sequence obtained by the decoding unit 813 based on the first error control coding method to generate a first bit stream. The interleaving unit 815 sorts the bit order of the first bit stream generated by the encoding unit 814 based on the first sorting rule. This sorting is also called interleaving.

[0248] The mapping unit 816 performs a mapping process on the first bit stream sorted by the interleaving unit 815 according to the first mapping method, and generates a first modulated symbol stream composed of a plurality of first modulated symbols. The multiplication unit 817 multiplies the first modulated symbol stream output by the mapping unit 816 by the first amplitude coefficient a 1 .

[0249] The delay unit 818 delays the received signal output from the RF unit 830 during the period from when the baseband received signal is output from the RF unit 830 to when the reproduced first modulated symbol stream is output by the multiplication unit 817

[0250] The subtraction unit 819 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 817 from the received signal delayed by the delay unit 818 1 of the first modulated symbol stream. Thus, the subtraction unit 819 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 819 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream

[0251] The transformation unit 820 uses the first bit stream reproduced through coding and interleaving, etc., to perform a transformation on the signal output from the subtraction unit 819 as the signal corresponding to the second modulated symbol stream. The demapping unit 821 demaps the signal output by the transformation unit 820 based on the second constellation of the second mapping method, and generates a second likelihood stream. For example, the amplitude coefficient a is reflected in the second constellation used for demapping 2 .

[0252] The deinterleaving unit 822 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also called deinterleaving. The decoding unit 823 performs a decoding process on the second likelihood stream sorted by the deinterleaving unit 822 based on the second error control coding method, and outputs the decoding result as the second data sequence

[0253] Taking the case where QPSK is used as the first mapping method as an example, the operation of the transformation unit 820 is described

[0254] For example, in S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 816, and b 1 (t) and b 2 (t) are the case where multiple bits are mapped to S 1 (t), the modulated symbol S 1 (t) is given by Equation 11

[0255] [Equation 11]

[0256]

[0257] Here, i is the imaginary unit. The modulation symbol S 1 (t) can also be given by an expression in which the polarity of one or both of the real part and the imaginary part of Expression 11 is inverted. Bit b 1 (t) is a bit that contributes to the real part of the modulation symbol S 1 (t). Bit b 2 (t) is a bit that contributes to the imaginary part of the modulation symbol S 1 (t).

[0258] Based on b 1 (t) and b 2 (t) as in Expression 12, the transformation unit 820 transforms the signal S 2 (t) corresponding to the t-th modulation symbol of the second modulation symbol stream in the signal output from the subtraction unit 819 into S’ 2 (t).

[0259] [Expression 12]

[0260]

[0261] Here, S’ 2 (t) is the transformed signal. In addition, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). The transformed signal S’ 2 (t) can also be given by an expression in which the polarity of one or both of the real part and the imaginary part of Expression 12 is inverted.

[0262] Through the above, the receiving device 800 obtains both or one of the first data sequence and the second data sequence from the signal received by the antenna.

[0263] Figure 17 An example of the structure of a receiving device 900 that represents receiving a signal formed by multiplexing two data sequences into two layers using the above-described differential superposition coding and performing successive decoding to be able to obtain both or one of the two multiplexed data sequences is shown. The structure of the receiving device 900 is different from the structure of the receiving device 800. Refer to Figure 17 to describe the structure and operation of the receiving device 900.

[0264] The receiving device 900 includes an RF unit 930, a demapping unit 911, a deinterleaving unit 912, a decoding unit 913, an encoding unit 914, an interleaving unit 915, a mapping unit 916, a multiplication unit 917, a delay unit 918, a subtraction unit 919, a transformation unit 920, a demapping unit 921, a deinterleaving unit 922, and a decoding unit 923. Each structural element may be a dedicated or general-purpose circuit.

[0265] The demapping unit 911, the deinterleaving unit 912, the decoding unit 913, the encoding unit 914, the interleaving unit 915, the mapping unit 916, the multiplication unit 917, the delay unit 918, the subtraction unit 919, the transformation unit 920, the demapping unit 921, the deinterleaving unit 922, and the decoding unit 923 may also be collectively represented as a derivation unit. The RF unit 930 may also be represented as a receiving unit. The RF unit 930 may also include an antenna.

[0266] The receiving device 900 receives the multiplexed signal transmitted from the transmitting devices 500, 600, or 700 using an antenna and inputs it to the RF unit 930. That is, the RF unit 930 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 930 is also represented as a received signal, corresponding to a superimposed modulation symbol stream formed by multiplexing a first modulation symbol stream and a second modulation symbol stream. The RF unit 930 generates a baseband received signal based on the received signal in the radio frequency band.

[0267] The demapping unit 911 demaps the baseband received signal based on the first constellation of the first mapping method, generating a first likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0268] The deinterleaving unit 912 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 913 uses the first likelihood stream sorted by the deinterleaving unit 912 to perform decoding processing based on the first error control coding method, and outputs the decoding result as a first data sequence.

[0269] Here, the demapping unit 911 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise), and demaps it based on the first constellation of the first mapping method.

[0270] When only the first data sequence is the acquisition target, the receiving device 900 ends the processing at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 900 performs the following processing to acquire the second data sequence.

[0271] The encoding unit 914 performs encoding on the first data sequence obtained by the decoding unit 913 based on the first error control coding method to generate a first bit stream. The interleaving unit 915 sorts the bit order of the first bit stream generated by the encoding unit 914 based on the first sorting rule. This sorting is also referred to as interleaving.

[0272] The mapping unit 916 performs mapping processing on the first bit stream sorted by the interleaving unit 915 according to the first mapping method to generate a first modulated symbol stream composed of a plurality of first modulated symbols. The multiplication unit 917 multiplies the first modulated symbol stream output by the mapping unit 916 by the first amplitude coefficient a 1 .

[0273] The delay unit 918 delays the received signal output from the RF unit 930 during the period from when the baseband received signal is output from the RF unit 930 until the first modulated symbol stream that has been reproduced is output by the multiplication unit 917.

[0274] The subtraction unit 919 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 917 from the received signal delayed by the delay unit 918 1 of the first modulated symbol stream. Thus, the subtraction unit 919 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 919 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream.

[0275] The transformation unit 920 uses the first modulated symbol stream reproduced through encoding, interleaving, and mapping, etc., to perform transformation on the signal output from the subtraction unit 919 as the signal corresponding to the second modulated symbol stream. The demapping unit 921 demaps the signal output by the transformation unit 920 based on the second constellation of the second mapping method to generate a second likelihood stream. For example, the amplitude coefficient a is reflected in the second constellation used for demapping 2 .

[0276] The deinterleaving unit 922 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 923 performs decoding processing on the second likelihood stream sorted by the deinterleaving unit 922 based on the second error control coding method, and outputs the decoding result as the second data sequence.

[0277] Taking the case where QPSK is used as the first mapping method as an example, the operation of the transformation unit 920 is described.

[0278] For example, in S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 916, and b 1 (t) and b2 (t) is mapped to S 1 When there are a plurality of bits of (t), the modulation symbol S is given by Equation 13 1 (t).

[0279] [Equation 13]

[0280]

[0281] Here, i is the imaginary unit. The modulation symbol S can also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 13 is inverted 1 (t). The bit b 1 (t) is the bit that contributes to the real part of the modulation symbol S 1 (t). The bit b 2 (t) is the bit that contributes to the imaginary part of the modulation symbol S 1 (t).

[0282] The transformation unit 920 transforms the signal S 1 (t) corresponding to the t-th modulation symbol of the second modulation symbol stream in the signal output from the subtraction unit 919 based on the modulation symbol S as in Equation 14 2 (t) into S' 2 (t).

[0283] [Equation 14]

[0284]

[0285] Here, S' 2 (t) is the transformed signal. In addition, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). In addition, sgn(Re[S 1 (t)]) is the polarity of the real part of S 1 (t), and sgn(Im[S 1 (t)]) is the polarity of the imaginary part of S1(t). The transformed signal S' 2 (t) can also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 14 is inverted. In addition, the transformation based on Equation 14 is substantially the same as the transformation based on Equation 12

[0286] Through the above, the receiving device 900 obtains both or one of the first data sequence and the second data sequence from the signal received by the antenna

[0287] Figure 18This shows an example of the structure of a receiving device 1000 that receives two data sequences multiplexed into a two-layered signal using the above-described transform superposition coding and performs successive decoding to obtain one or both of the two multiplexed data sequences. The structure of the receiving device 1000 is different from that of the receiving devices 800 and 900. Refer to Figure 18 to describe the structure and operation of the receiving device 1000.

[0288] The receiving device 1000 includes an RF unit 1030, a demapping unit 1011, an interleaving unit 1012, a decoding unit 1013, an encoding unit 1014, an interleaving unit 1015, a mapping unit 1016, a multiplication unit 1017, a delay unit 1018, a subtraction unit 1019, a demapping unit 1021, an interleaving unit 1022, and a decoding unit 1023. Each structural element may be a dedicated or general-purpose circuit.

[0289] The demapping unit 1011, the interleaving unit 1012, the decoding unit 1013, the encoding unit 1014, the interleaving unit 1015, the mapping unit 1016, the multiplication unit 1017, the delay unit 1018, the subtraction unit 1019, the demapping unit 1021, the interleaving unit 1022, and the decoding unit 1023 may also be collectively represented as a derivation unit. The RF unit 1030 may also be represented as a receiving unit. The RF unit 1030 may also include an antenna. The demapping unit 1021 may also include a transformation unit.

[0290] The receiving device 1000 receives the multiplexed signal transmitted from the transmitting devices 500, 600, or 700 using an antenna and inputs it to the RF unit 1030. That is, the RF unit 1030 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1030 is also represented as a received signal, corresponding to a superposition modulation symbol stream multiplexed from a first modulation symbol stream and a second modulation symbol stream. The RF unit 1030 generates a baseband received signal based on the received signal in the radio frequency band.

[0291] The demapping unit 1011 demaps the baseband received signal based on the first constellation of the first mapping method, generating a first likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping 1 .

[0292] The interleaving unit 1012 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1013 performs decoding processing based on the first error control coding method using the first likelihood stream sorted by the interleaving unit 1012 and outputs the decoding result as the first data sequence.

[0293] Here, the demapping unit 1011 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise), and performs demapping based on the first constellation of the first mapping method.

[0294] When only the first data sequence is the acquisition target, the receiving device 1000 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 1000 performs the following process to acquire the second data sequence.

[0295] The encoding unit 1014 encodes the first data sequence acquired by the decoding unit 1013 based on the first error control coding method to generate a first bit stream. The interleaving unit 1015 sorts the bit order of the first bit stream generated by the encoding unit 1014 based on the first sorting rule. This sorting is also called interleaving.

[0296] The mapping unit 1016 performs mapping processing on the first bit stream sorted by the interleaving unit 1015 according to the first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. The multiplication unit 1017 multiplies the first modulation symbol stream output by the mapping unit 1016 by the first amplitude coefficient a 1 .

[0297] The delay unit 1018 delays the received signal output from the RF unit 1030 during the period from when the baseband received signal is output from the RF unit 1030 to when the reproduced first modulation symbol stream is output by the multiplication unit 1017.

[0298] The subtraction unit 1019 subtracts the first modulation symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 1017 from the received signal delayed by the delay unit 1018 1 . Thus, the subtraction unit 1019 removes the component corresponding to the first modulation symbol from the received signal superimposed with the component corresponding to the first modulation symbol, the component corresponding to the second modulation symbol, and noise. Then, the subtraction unit 1019 outputs the signal superimposed with the component corresponding to the second modulation symbol and noise as a signal corresponding to the second modulation symbol stream.

[0299] The demapping unit 1021 demaps the signal output from the subtraction unit 1019 as a signal corresponding to the second modulation symbol stream based on the second constellation of the second mapping method to generate a second likelihood stream. At this time, the first bit stream reproduced through encoding and interleaving, etc. is reflected in this process. In addition, for example, the amplitude coefficient a is reflected in the second constellation used for demapping 2 .

[0300] The deinterleaving unit 1022 sorts the second likelihood stream based on a sorting rule opposite to the second sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1023 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 1022, and outputs the decoding result as a second data sequence.

[0301] Taking the case where QPSK is used as the first mapping method as an example, the operation of the demapping unit 1021 will be described.

[0302] For example, in S 1 (t) is the t-th modulation symbol of the first modulated symbol stream generated by the mapping unit 1016, and b 1 (t) and b 2 (t) are the cases where multiple bits are mapped to S 1 (t), the modulation symbol S 1 (t) is given by Equation 15.

[0303] [Equation 15]

[0304]

[0305] Here, i is the imaginary unit. The modulation symbol S1(t) can also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 15 is inverted. The bit b 1 (t) is the bit that contributes to the real part of the modulation symbol S 1 (t). The bit b 2 (t) is the bit that contributes to the imaginary part of the modulation symbol S 1 (t).

[0306] The demapping unit 1021 demaps the signal S 2 (t) output from the subtraction unit 1019 as a signal corresponding to the t-th modulation symbol of the second modulated symbol stream based on the second constellation of the second mapping method.

[0307] The demapping unit 1021 performs an inversion process corresponding to b 1 (t) on the bit likelihood corresponding to the bit that contributes most to the real part of the second constellation in the bit likelihood stream obtained by demapping. In addition, the demapping unit 1021 performs an inversion process corresponding to b 2 (t) on the bit likelihood corresponding to the bit that contributes most to the imaginary part of the second constellation in the bit likelihood stream obtained by demapping.

[0308] For example, the demapping unit 1021 performs b 1Exclusive OR logical operation of (t). In addition, the demapping unit 1021 performs b on the bit likelihood corresponding to the bit in the bit likelihood stream obtained by demapping that contributes most to the imaginary part of the second constellation. 2 Exclusive OR logical operation of (t).

[0309] The demapping unit 1021 outputs the bit likelihood stream after performing the above-mentioned inversion process as the second bit likelihood stream.

[0310] In the above, the demapping unit 1021 substantially transforms the second mapping method (second constellation) by transforming the bit likelihood stream. However, the demapping unit 1021 may also directly transform the second mapping method (second constellation) without transforming the bit likelihood stream. That is, the demapping unit 1021 may also transform the correspondence between the bit groups and the signal points in the second constellation.

[0311] In addition, the transformation performed by the demapping unit 1021 may also be performed by a transformation unit included in the demapping unit 1021.

[0312] Through the above, the receiving device 1000 obtains both or one of the first data sequence and the second data sequence from the signal received by the antenna.

[0313] <Parallel decoding of the signal obtained by deformed superposition coding>

[0314] Next, a receiving method for parallel decoding of the signal obtained by deformed superposition coding in the present embodiment will be described. The structure of the transmitting device is the same as that of Figure 13 the transmitting device 500 shown, Figure 14 the transmitting device 600 shown, or Figure 15 the transmitting device 700 shown, so the description thereof is omitted. In the parallel decoding in deformed superposition coding, the receiving device does not remove the component of the first-layer modulation symbol stream included in the received signal, but treats the component of the first-layer modulation symbol stream as an unknown signal (noise) and decodes the second layer.

[0315] Figure 19 An example of the structure of a receiving device 1100 that receives a signal multiplexed with two data sequences into two layers using deformed superposition coding and performs parallel decoding to be able to obtain both or one of the two multiplexed data sequences is shown. Refer to Figure 19 to describe the structure and operation of the receiving device 1100.

[0316] The receiving device 1100 includes an RF unit 1130, a demapping unit 1110, an interleaving unit 1112, a decoding unit 1113, an interleaving unit 1122, and a decoding unit 1123. Each structural element may be a dedicated or general-purpose circuit. The demapping unit 1110, the interleaving unit 1112, the decoding unit 1113, the interleaving unit 1122, and the decoding unit 1123 may also be collectively represented as a derivation unit. The RF unit 1130 may also be represented as a receiving unit. The RF unit 1130 may also include an antenna.

[0317] The receiving device 1100 receives the multiplexed signal transmitted from the transmitting devices 500, 600, or 700 using an antenna and inputs it to the RF unit 1130. That is, the RF unit 1130 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1130 may also be represented as a received signal. The RF unit 1130 generates a baseband received signal based on the received signal in the radio frequency band.

[0318] The demapping unit 1110 demaps the baseband received signal to generate a first likelihood stream and a second likelihood stream. The demapping unit 1110 demaps, for example, based on a deformed superposition constellation representing the configuration of signal points of a superposition modulation symbol obtained by superposing a first modulation symbol and a second modulation symbol using deformed superposition coding.

[0319] The deformed superposition constellation is determined according to a first constellation of a first mapping method, a second constellation of a second mapping method, a first amplitude coefficient a 1 and a second amplitude coefficient a 2 and so on.

[0320] Figure 20 FIG. shows an example of a deformed superposition constellation corresponding to deformed superposition coding. Specifically, Figure 4 the constellation of QPSK shown in FIG. is combined with Figure 5 the constellation of Nu-256QAM shown in FIG.

[0321] More specifically, according to the four signal points of the QPSK constellation, the constellation of Nu-256QAM (256 signal points) is arranged in each of the four regions on the complex plane. These four regions corresponding to the constellation of Nu-256QAM may also partially overlap. Moreover, the transformation of the second modulation symbol stream is reflected in this deformed superposition constellation.

[0322] For example, when combining the constellation of Nu-256QAM with the signal points of the QPSK constellation having a positive real part, the polarity of the real part of the constellation of Nu-256QAM is reversed. Additionally, for example, when combining the constellation of Nu-256QAM with the signal points of the QPSK constellation having a positive imaginary part, the polarity of the imaginary part of the constellation of Nu-256QAM is reversed.

[0323] Specifically, in Figure 20 a first signal point, a second signal point, a third signal point, a fourth signal point, a fifth signal point, and a sixth signal point are shown. When the polarity of the real part of the constellation of Nu-256QAM does not reverse, the first signal point and the third signal point correspond to the same bit value for the second bit stream. Similarly, when the polarity of the imaginary part of the constellation of Nu-256QAM does not reverse, the fourth signal point and the sixth signal point correspond to the same bit value for the second bit stream.

[0324] When the polarity of the real part of the constellation of Nu-256QAM reverses, the first signal point and the second signal point correspond to the same bit value for the second bit stream. Additionally, when the polarity of the imaginary part of the constellation of Nu-256QAM reverses, the fourth signal point and the fifth signal point correspond to the same bit value for the second bit stream. That is, multiple signal points corresponding to the same bit value for the second bit stream approach each other through inversion and are thus concentrated. Thereby, the influence on the demapping affected by noise is suppressed.

[0325] The demapping unit 1110 performs demapping based on the deformed superposition constellation as Figure 20 shown. That is, the demapping unit 1110 generates a first likelihood stream in a state where the modulated symbol stream of the second layer is unknown, and generates a second likelihood stream in a state where the modulated symbol stream of the first layer is unknown.

[0326] Furthermore, the demapping unit 1110 may use the first constellation of the first mapping method in the generation of the first likelihood stream, and use the above-mentioned deformed superposition constellation in the generation of the second likelihood stream.

[0327] When the demapping unit 1110 uses the first constellation in the generation of the first likelihood stream, compared with the case where the deformed superposition constellation is also used in the generation of the first likelihood stream, the number of signal points considered in the generation of the first likelihood stream can be reduced. Thus, in this case, the demapping unit 1110 can reduce the amount of computation.

[0328] In addition, for example, the demapping unit 1110 corresponds to: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal. The demapping unit 1110 may also include: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal.

[0329] In addition, the demapping unit 1110 can also transform the second likelihood stream generated using a superimposed constellation rather than a deformed superimposed constellation according to the first likelihood stream. Thereby, the demapping unit 1110 can obtain the same second likelihood stream as the second likelihood stream generated using the deformed superimposed constellation.

[0330] In addition, the demapping unit 1110 can also transform the multiplexed signal without using the deformed superimposed constellation to obtain the same second likelihood stream as the second likelihood stream generated using the deformed superimposed constellation.

[0331] The deinterleaving unit 1112 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1113 performs a decoding process based on the first error control coding method on the first likelihood stream sorted by the deinterleaving unit 1112, and outputs the decoding result as the first data sequence.

[0332] The deinterleaving unit 1122 sorts the second likelihood stream based on a sorting rule opposite to the second sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1123 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 1122, and outputs the decoding result as the second data sequence.

[0333] Through the above, the receiving device 1100 obtains either or both of the first data sequence and the second data sequence from the signal received by the antenna.

[0334] In addition, in the transmitting devices 500, 600, and 700 and the receiving devices 800, 900, 1000, and 1100, similar to the first embodiment, sorting (interleaving and deinterleaving) can also be omitted. That is, each interleaving unit and each deinterleaving unit are optional structural elements and may not be included in these devices.

[0335] However, interleaving and deinterleaving form a pair. Therefore, basically, when the transmitting devices 500, 600, and 700 are provided with respective interleaving units, the receiving devices 800, 900, 1000, and 1100 are provided with respective deinterleaving units and respective interleaving units. On the other hand, when the transmitting devices 500, 600, and 700 are not provided with respective interleaving units, the receiving devices 800, 900, 1000, and 1100 are not provided with respective deinterleaving units and respective interleaving units.

[0336] In addition, in the receiving devices 800, 900, and 1000, the amplitude coefficient a can also be reflected in the mapping for generating the first modulation symbol. 1 . In this case, the amplitude coefficient a can also be omitted. 1Multiplication processing. Moreover, the receiving devices 800, 900, and 1000 may not separately include the multiplication units 817, 917, and 1017.

[0337] In addition, the error control coding of the first data sequence and the second data sequence may also be performed by an external device. In this case, in the transmitting devices 500, 600, and 700, the error control coding may also be omitted. Moreover, the transmitting devices 500, 600, and 700 may not include the coding units 511, 521, 611, 621, 711, and 721.

[0338] Figure 21 It is a flowchart showing an operation example of the transmitting device 500. First, the mapping unit 513 generates a first modulated symbol stream of the first data sequence by mapping the first bit stream of the first data sequence (S301). Then, the mapping unit 523 generates a second modulated symbol stream of the second data sequence by mapping the second bit stream of the second data sequence (S302).

[0339] The transformation unit 525 gives a transformation corresponding to the first modulated symbol stream to the second modulated symbol stream (S303). Specifically, the transformation unit 525 gives a transformation corresponding to the first modulated symbol stream to the second modulated symbol stream by transforming the second modulated symbol stream according to the first bit stream.

[0340] Next, the superimposing unit composed of the first multiplication unit 514, the second multiplication unit 524, and the addition unit 530 generates a multiplexed signal by superimposing the first modulated symbol stream and the second modulated symbol stream given the transformation corresponding to the first modulated symbol stream at a prescribed amplitude ratio (S304). Then, the RF unit 540 transmits the generated multiplexed signal (S305).

[0341] In addition, in the above operation example, the transmitting device 500 gives a transformation corresponding to the first modulated symbol stream to the second modulated symbol stream by transforming the second modulated symbol stream according to the first bit stream (S303). Instead, as in the case of the transmitting device 600, a transformation corresponding to the first modulated symbol stream may be given to the second modulated symbol stream by transforming the second modulated symbol stream according to the first modulated symbol stream.

[0342] Alternatively, as in the case of the transmitting device 700, the second bit stream or the second mapping method (second constellation) used to generate the second modulated symbol stream may be transformed according to the first bit stream. Then, thereby, a transformation corresponding to the first modulated symbol stream may be given to the second modulated symbol stream. In this case, the second bit stream or the second mapping method is transformed before the second modulated symbol stream is generated.

[0343] That is, the transformation corresponding to the first modulated symbol stream can also be imparted to the second modulated symbol stream by transforming the second bit stream, the second mapping method, or the second modulated symbol stream according to the first bit stream or the first modulated symbol stream.

[0344] In addition, the transformation unit 525 can also control the polarities of the real part and the imaginary part of each modulated symbol in the second modulated symbol stream by imparting the transformation corresponding to the first modulated symbol stream to the second modulated symbol stream. Thus, the transformation unit 525 can also reverse the polarity of the real part of the second modulated symbol when the real part of the first modulated symbol satisfies a specified real part condition, and reverse the polarity of the imaginary part of the second modulated symbol when the imaginary part of the first modulated symbol satisfies a specified condition.

[0345] The specified real part condition can be either a condition that the polarity of the real part is a specified real part polarity, or a condition that the real part is within a specified real part range of 1 or more. The specified real part range of 1 or more can be either a positive range or a negative range. Similarly, the specified imaginary part condition can be either a condition that the polarity of the imaginary part is a specified imaginary part polarity, or a condition that the imaginary part is within a specified imaginary part range of 1 or more. The specified imaginary part range of 1 or more can be either a positive range or a negative range.

[0346] Figure 22 FIG. 40 is a flowchart showing an operation example of the receiving apparatuses 800, 900, 1000, and 1100. First, the receiving unit receives the multiplexed signal (S401). Here, the receiving unit is the RF unit 830 of the receiving apparatus 800, the RF unit 930 of the receiving apparatus 900, the RF unit 1030 of the receiving apparatus 1000, or the RF unit 1130 of the receiving apparatus 1100.

[0347] The multiplexed signal is a signal in which a plurality of data sequences including the first data sequence of the first layer and the second data sequence of the second layer are multiplexed. In addition, the multiplexed signal is a signal in which the first modulated symbol stream and the second modulated symbol stream are superimposed at a specified amplitude ratio.

[0348] The first modulated symbol stream is a modulated symbol stream generated by mapping the first bit stream of the first data sequence. The second modulated symbol stream is a modulated symbol stream generated by mapping the second bit stream of the second data sequence and to which the transformation corresponding to the first modulated symbol stream is imparted.

[0349] Next, the derivation unit derives at least one of the first data sequence and the second data sequence from the multiplexed signal (S402).

[0350] For example, the derivation unit of the receiving device 800 is composed of a demapping unit 811, a deinterleaving unit 812, a decoding unit 813, an encoding unit 814, an interleaving unit 815, a mapping unit 816, a multiplication unit 817, a delay unit 818, a subtraction unit 819, a transformation unit 820, a demapping unit 821, a deinterleaving unit 822, and a decoding unit 823.

[0351] In addition, for example, the derivation unit of the receiving device 900 is composed of a demapping unit 911, a deinterleaving unit 912, a decoding unit 913, an encoding unit 914, an interleaving unit 915, a mapping unit 916, a multiplication unit 917, a delay unit 918, a subtraction unit 919, a transformation unit 920, a demapping unit 921, a deinterleaving unit 922, and a decoding unit 923.

[0352] In addition, for example, the derivation unit of the receiving device 1000 is composed of a demapping unit 1011, a deinterleaving unit 1012, a decoding unit 1013, an encoding unit 1014, an interleaving unit 1015, a mapping unit 1016, a multiplication unit 1017, a delay unit 1018, a subtraction unit 1019, a demapping unit 1021, a deinterleaving unit 1022, and a decoding unit 1023.

[0353] In addition, for example, the derivation unit of the receiving device 1100 is composed of a demapping unit 1110, a deinterleaving unit 1112, a decoding unit 1113, a deinterleaving unit 1122, and a decoding unit 1123.

[0354] According to the above operation, a multiplexed signal in which a first modulated symbol stream and a second modulated symbol stream having a transformation corresponding to the first modulated symbol stream are superimposed is received. Then, at least one of a first data sequence and a second data sequence is derived from the multiplexed signal. That is, by receiving a multiplexed signal superimposed in a manner that reduces the degradation of performance during parallel decoding, both or one of the first data sequence and the second data sequence can be efficiently derived from the multiplexed signal.

[0355] In Figure 19 the receiving device 1100 performing parallel decoding shown, compared with Figure 16 , 17 and the receiving devices 800, 900, and 1000 performing successive decoding shown in 18, the decoding performance of the second layer deteriorates.

[0356] In Figure 23 is shown an example of the simulation result of the transmission capacity of the second layer in the case where the ratio of the signal power P s1 of the first layer to the signal power P s2 of the second layer is P s1 : P s2 = 2:1. In Figure 23 , the horizontal axis represents the signal power P sRatio (SNR) with noise power P n The vertical axis represents the transmission capacity. In Figure 23 the solid line represents the transmission capacity of the second layer in the case of successive decoding, and the dashed line represents the transmission capacity of the second layer in the case of parallel decoding.

[0357] As Figure 23 shown, in the case of parallel decoding, compared with the case of successive decoding, in the decoding of the second layer, for the same transmission capacity, the required SNR increases, and for the same SNR, the transmission capacity decreases.

[0358] As described above, the receiving device 1100 performing parallel decoding in the present embodiment has deteriorated decoding performance related to the second data sequence transmitted in the second layer compared to the receiving devices 800, 900, and 1000 performing successive decoding. However, the structure required for decoding the second layer can be reduced.

[0359] Specifically, in the receiving device 1100, compared with Figure 16 , 17 and the receiving devices 800, 900, and 1000 performing successive decoding shown in 18, the structural elements for reproducing the modulated symbol stream of the first layer are not required. That is, the encoding units 814, 914, and 1014, the interleaving units 815, 915, and 1015, the mapping units 816, 916, and 1016, and the multiplication units 817, 917, and 1017 are not required.

[0360] In addition, the delay units 818, 918, and 1018 for delaying the received signal and the subtraction units 819, 919, and 1019 for removing the components of the modulated symbols of the reproduced first layer from the received signal are not required.

[0361] Therefore, the circuit scale can be reduced. In addition, the receiving device 1100 can reduce the amount of computation compared to the receiving devices 800, 900, and 1000, and can reduce the power consumption.

[0362] And Figure 16 , 17 and the receiving devices 800, 900, and 1000 performing successive decoding shown in 18 demodulate the first layer of the received signal to obtain the first data sequence, and generate the first modulated symbol stream based on the obtained first data sequence. Moreover, after that, the receiving devices 800, 900, and 1000 start demodulating the second layer of the received signal to obtain the second data sequence.

[0363] On the other hand, the receiving device 1100 performing parallel decoding in the present embodiment can perform the acquisition of the first data sequence and the acquisition of the second data sequence simultaneously in parallel, so the processing delay can be shortened.

[0364] In addition, the receiving device can also observe the SNR of the received signal and switch the decoding process in such a way that parallel decoding is performed when the SNR is high and successive decoding is performed when the SNR is low.

[0365] In this case, for example, Figure 16 the receiving device 800 shown has a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may be included in the RF unit 830 or the demapping unit 821. Also, the demapping unit 821 has a structure that performs, in addition to the demapping process based on the second constellation, the demapping process based on the deformed superimposed constellation as described for the operation of the demapping unit 1110. Figure 19 the demapping unit 821 switches the demapping process based on the second constellation for the signal output from the transformation unit 820 and the demapping process based on the deformed superimposed constellation for the signal output from the RF unit 830. For example, the demapping unit 821 switches these demapping processes according to the control signal from the control unit.

[0366] Then,

[0367] Furthermore, such a structure is also obtained by Figure 11 the combination of the receiving device 400 shown, Figure 16 the receiving device 800 (such as the transformation unit 820 and the demapping unit 821) shown, and Figure 19 the receiving device 1100 (such as the demapping unit 1110) shown.

[0368] As another structure, for example, Figure 17 the receiving device 900 shown has a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may be included in the RF unit 930 or the demapping unit 921. Also, the demapping unit 921 has a structure that performs, in addition to the demapping process based on the first bit stream and the second constellation, the demapping process based on the deformed superimposed constellation as described for the operation of the demapping unit 1110. Figure 19 the demapping unit 921 switches the demapping process based on the second constellation for the signal output from the transformation unit 920 and the demapping process based on the deformed superimposed constellation for the signal output from the RF unit 930. For example, the demapping unit 921 switches these demapping processes according to the control signal from the control unit.

[0369] Then,

[0370] Furthermore, such a structure is also obtained by Figure 11 the combination of the receiving device 400 shown, Figure 17 the receiving device 900 (such as the transformation unit 920 and the demapping unit 921) shown, and Figure 19obtained by combining the receiving device 1100 (such as the demapping unit 1110) shown.

[0371] As another configuration, for example, Figure 18 the receiving device 1000 shown includes a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may also be included in the RF unit 1030 or the demapping unit 1021. Further, the demapping unit 1021 has a configuration that performs, in addition to the demapping process based on the first bit stream and the second constellation, the demapping process based on the deformed superposition constellation as described in the operation of the demapping unit 1110. Figure 19 the operation of the demapping unit 1110.

[0372] Then, the demapping unit 1021 switches the demapping process based on the second constellation for the signal output from the subtraction unit 1019 and the demapping process based on the deformed superposition constellation for the signal output from the RF unit 1030. For example, the demapping unit 1021 switches these demapping processes according to a control signal from the control unit.

[0373] In addition, such a configuration is also obtained by Figure 11 the combination of the receiving device 400 shown, Figure 18 the receiving device 1000 (such as the demapping unit 1021) shown, and Figure 19 the receiving device 1100 (such as the demapping unit 1110) shown.

[0374] In this way, when the SNR is high, the receiving devices 800, 900, and 1000 can reduce the amount of computation and power consumption by performing parallel decoding. Further, when the SNR is high, the receiving devices 800, 900, and 1000 can shorten the processing delay by performing parallel decoding. On the other hand, when the SNR is low, the possibility that the receiving devices 800, 900, and 1000 can accurately decode the second data sequence by performing successive decoding becomes high.

[0375] When Figure 10 the transmission capacity based on the multiplexing method using superimposed coding shown is compared with Figure 23 the transmission capacity based on the multiplexing method using deformed superimposed coding shown, the following is found.

[0376] That is, regarding the characteristics of the transmission capacity based on successive decoding (solid line), the multiplexing method using superimposed coding ( Figure 10 ) is the same as the multiplexing method using deformed superimposed coding ( Figure 23 ). On the other hand, regarding the characteristics of the transmission capacity based on parallel decoding (dashed line), the multiplexing method using deformed superimposed coding ( Figure 23 ) has a higher transmission capacity than the multiplexing method using superimposed coding ( Figure 10) is more improved. That is, the multiplexing method using the transformed superposition coding provides desired results both in the case of successive decoding and in the case of parallel decoding.

[0377] (Embodiment 4)

[0378] <Transformed Superposition Coding (Variant Superposition Coding)>

[0379] In this embodiment, a method of multiplexing and transmitting a plurality of data sequences using the transformed superposition coding (variant superposition coding) obtained by transforming the above-mentioned superposition coding is described.

[0380] Figure 24 An example of the structure of the transmitting device 1200 that multiplexes two data sequences into two layers and transmits them using the transformed superposition coding is shown. Refer to Figure 24 to describe the structure and operation of the transmitting device 1200.

[0381] The transmitting device 1200 includes an encoding unit 1211, an interleaving unit 1212, a mapping unit 1213, a multiplication unit 1214, an encoding unit 1221, an interleaving unit 1222, a mapping unit 1223, a transformation unit 1225, a multiplication unit 1224, an addition unit 1230, and an RF unit 1240. Each structural element can be a dedicated or general-purpose circuit. The multiplication unit 1214, the multiplication unit 1224, and the addition unit 1230 can also be collectively represented as a superposition unit. The RF unit 1240 can also be represented as a transmitting unit. The RF unit 1240 may also include an antenna.

[0382] The encoding unit 1211 encodes the input first data sequence based on the first error control coding method to generate a first bit stream. The interleaving unit 1212 sorts the bit order of the first bit stream generated by the encoding unit 1211 based on the first sorting rule. This sorting is also called interleaving.

[0383] The mapping unit 1213 performs a mapping process on the first bit stream sorted by the interleaving unit 1212 according to the first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. In the mapping process according to the first mapping method, the mapping unit 1213 maps the first bit stream in groups of the first number of bits to one of the plurality of signal points in the first constellation according to the value of the bit group.

[0384] When using PSK modulation such as BPSK and QPSK, or QAM modulation such as 16QAM and 64QAM as the first mapping method, the first modulation symbol can be represented by a complex number that can use, for example, a real number to represent the magnitude of the in-phase component and an imaginary number to represent the magnitude of the quadrature component. In addition, when using PAM modulation as the first mapping method, the first modulation symbol can be represented by a real number.

[0385] The encoding unit 1221 performs encoding on the input second data sequence based on the second error control coding method to generate a second bit stream. The interleaving unit 1222 sorts the bit order of the second bit stream generated by the encoding unit 1221 based on the second sorting rule. This sorting is also referred to as interleaving.

[0386] The mapping unit 1223 performs mapping processing on the second bit stream sorted by the interleaving unit 1222 according to the second mapping method to generate a second modulation symbol stream composed of a plurality of second modulation symbols. In the mapping processing according to the second mapping method, the mapping unit 1223 maps each bit group of the second bit stream with a value of the bit group to a certain signal point among a plurality of signal points in the second constellation.

[0387] In the case where PSK modulation such as BPSK and QPSK, or QAM modulation such as 16QAM and 64QAM is used as the second mapping method, the second modulation symbol can be represented by a complex number that can use, for example, a real number to represent the magnitude of the in-phase component and an imaginary number to represent the magnitude of the quadrature component. In addition, in the case where PAM modulation is used as the second mapping method, the second modulation symbol can be represented by a real number. In the second mapping method, either a uniform constellation or a non-uniform constellation can be used.

[0388] The transformation unit 1225 performs transformation on the second modulation symbol superimposed on the first modulation symbol based on the value used in the generation of the first modulation symbol. Thus, the transformation unit 1225 performs transformation on the second modulation symbol stream.

[0389] The multiplication unit 1214 multiplies the first modulation symbol of the first modulation symbol stream by the first amplitude coefficient a 1 . The multiplication unit 1224 multiplies the second modulation symbol of the second modulation symbol stream transformed by the transformation unit 1225 by the second amplitude coefficient a 2 .

[0390] The multiplication unit 1224 can multiply both the real part and the imaginary part of the second modulation symbol by the second amplitude coefficient a 2 , or can multiply only one of them by the second amplitude coefficient a 2 . Alternatively, the multiplication unit 1224 can multiply the real part and the imaginary part of the second modulation symbol by different amplitude coefficients.

[0391] For example, in the case where the first modulation symbol consists only of a real part, the multiplication unit 1224 can also multiply only the real part of the second modulation symbol by the second amplitude coefficient a 2 . The multiplication unit 1224 can either not multiply the imaginary part of the second modulation symbol by an amplitude coefficient or multiply it by an amplitude coefficient smaller than the second amplitude coefficient a 2 .

[0392] The adder 1230 superimposes the first modulation symbol multiplied by the first amplitude coefficient a 1 and the second modulation symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulation symbol stream composed of a plurality of superimposed modulation symbols.

[0393] The RF unit 1240 transmits the generated superimposed modulation symbol stream as a signal. Specifically, the RF unit 1240 generates a radio band signal based on the superimposed modulation symbol stream generated by the adder 1230 as a signal corresponding to the superimposed modulation symbol stream, and transmits the radio band signal from the antenna.

[0394] That is, the superimposing unit composed of the multiplier 1214, the multiplier 1224, and the adder 1230 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio. Then, the RF unit 1240 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulation symbol stream.

[0395] In addition, the specified amplitude ratio can be equal (for example, 1:1), or the multiplication process can be omitted. In addition, in the superimposition of the first modulation symbol stream and the second modulation symbol stream, an amplitude ratio composed of the ratio of the first modulation symbol stream, the ratio of the real part of the second modulation symbol stream, and the ratio of the imaginary part of the second modulation symbol stream can also be used as the specified amplitude ratio. Moreover, the ratio of the part of the real part and the imaginary part where the first modulation symbol stream does not have a component can be made larger. In addition, the ratio can also be expressed as a weight.

[0396] Taking the case where BPSK is used as the first mapping method as an example, the operation of the conversion unit 1225 will be described.

[0397] For example, when S 1 (t) is the t-th modulation symbol of the first modulation symbol stream generated by the mapping unit 1213, and b 1 (t) is the bit mapped to S 1 (t), the modulation symbol S 1 (t) is given by Equation 16.

[0398] [Equation 16]

[0399] S 1 (t) = 2·b 1 (t) - 1 (Equation 16)

[0400] The modulation symbol S 1 (t) can also be given by an equation in which the polarity (positive and negative) of Equation 16 is reversed. The conversion unit 1225 is based on b as shown in Equation 17 1(t) Transform the t-th modulation symbol S of the second modulated symbol stream generated by the mapping unit 1223 2 (t) into S’ 2 (t).

[0401] [Number 17]

[0402]

[0403] Here, S’ 2 (t) is the t-th modulation symbol of the transformed second modulated symbol stream. Additionally, i is the imaginary unit. Additionally, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). The modulated symbol S’ 2 (t) can also be given by an expression in which the polarity of one or both of the real part and the imaginary part of Equation 17 is reversed.

[0404] As described above, the polarity of the real part of the second modulation symbol is controlled according to the value of the bit of the first modulation symbol mapped to be superimposed on the second modulation symbol. In addition, the polarity of the real part of the second modulation symbol can also be controlled according to the first modulation symbol superimposed on the second modulation symbol.

[0405] In addition, in the above, superposition coding is performed on the real part. That is, the first modulation symbol is composed of a real component, and the real component of the first modulation symbol and the real component of the second modulation symbol are superimposed on one real component. However, superposition coding can also be performed on the imaginary part. That is, it can also be that the first modulation symbol is composed of an imaginary component, and the imaginary component of the first modulation symbol and the imaginary component of the second modulation symbol are superimposed on one imaginary component.

[0406] Figure 25 An example of the structure of the transmitting device 1300 that multiplexes two data sequences onto two layers and transmits them using deformed superposition coding is shown. The structure of the transmitting device 1300 is different from the structure of the transmitting device 1200. Refer to Figure 25 to describe the structure and operation of the transmitting device 1300.

[0407] The transmitting device 1300 includes an encoding unit 1311, an interleaving unit 1312, a mapping unit 1313, a multiplication unit 1314, an encoding unit 1321, an interleaving unit 1322, a mapping unit 1323, a transformation unit 1325, a multiplication unit 1324, an addition unit 1330, and an RF unit 1340. Each structural element may be a dedicated or general-purpose circuit. The multiplication unit 1314, the multiplication unit 1324, and the addition unit 1330 may also be collectively represented as a superposition unit. The RF unit 1340 may also be represented as a transmitting unit. The RF unit 1340 may also include an antenna.

[0408] The encoding unit 1311 encodes the input first data sequence based on a first error control coding method to generate a first bit stream. The interleaving unit 1312 sorts the bit order of the first bit stream generated by the encoding unit 1311 based on a first sorting rule. This sorting is also referred to as interleaving.

[0409] The mapping unit 1313 performs a mapping process on the first bit stream sorted by the interleaving unit 1312 according to a first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. In the mapping process according to the first mapping method, the mapping unit 1313 maps each bit group of the first bit stream with a value of the bit group to one of the plurality of signal points in the first constellation.

[0410] The encoding unit 1321 encodes the input second data sequence based on a second error control coding method to generate a second bit stream. The interleaving unit 1322 sorts the bit order of the second bit stream generated by the encoding unit 1321 based on a second sorting rule. This sorting is also referred to as interleaving.

[0411] The mapping unit 1323 performs a mapping process on the second bit stream sorted by the interleaving unit 1322 according to a second mapping method to generate a second modulation symbol stream composed of a plurality of second modulation symbols. In the mapping process according to the second mapping method, the mapping unit 1323 maps each bit group of the second bit stream with a value of the bit group to one of the plurality of signal points in the second constellation.

[0412] The transformation unit 1325 performs a transformation on the second modulation symbol superimposed on the generated first modulation symbol based on the first modulation symbol. Thus, the transformation unit 1325 performs a transformation on the second modulation symbol stream.

[0413] The multiplication unit 1314 multiplies the first modulation symbol of the first modulation symbol stream by a first amplitude coefficient a 1 . The multiplication unit 1324 multiplies the second modulation symbol of the second modulation symbol stream transformed by the transformation unit 1325 by a second amplitude coefficient a 2 .

[0414] The multiplication unit 1324 can multiply both the real part and the imaginary part of the second modulation symbol by the second amplitude coefficient a 2 , or can multiply only one of them by the second amplitude coefficient a 2 . Alternatively, the multiplication unit 1324 can multiply the real part and the imaginary part of the second modulation symbol by different amplitude coefficients.

[0415] For example, when the first modulation symbol consists only of a real part, the multiplication unit 1324 can multiply only the real part of the second modulation symbol by the second amplitude coefficient a 2 . The multiplication unit 1324 can either not multiply the imaginary part of the second modulation symbol by an amplitude coefficient or multiply it by an amplitude coefficient smaller than the second amplitude coefficient a 2 .

[0416] The addition unit 1330 superimposes the first modulation symbol multiplied by the first amplitude coefficient a 1 and the second modulation symbol multiplied by the second amplitude coefficient a 2 to generate a superimposed modulation symbol stream composed of a plurality of superimposed modulation symbols.

[0417] The RF unit 1340 transmits the generated superimposed modulation symbol stream as a signal. Specifically, the RF unit 1340 generates a radio band signal based on the superimposed modulation symbol stream generated by the addition unit 1330 as a signal corresponding to the superimposed modulation symbol stream, and transmits the radio band signal from the antenna.

[0418] That is, the superimposing unit composed of the multiplication unit 1314, the multiplication unit 1324, and the addition unit 1330 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio. Then, the RF unit 1340 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superimposed modulation symbol stream.

[0419] In addition, the specified amplitude ratio can be equal (e.g., 1:1), or the multiplication process can be omitted. In addition, in the superimposition of the first modulation symbol stream and the second modulation symbol stream, an amplitude ratio composed of the ratio of the first modulation symbol stream, the ratio of the real component of the second modulation symbol stream, and the ratio of the imaginary component of the second modulation symbol stream can be used as the specified amplitude ratio. Moreover, the ratio of the part of the real component and the imaginary component that the first modulation symbol stream does not have can be made larger. In addition, the ratio can be expressed as a weight.

[0420] The operation of the transformation unit 1325 will be described by taking the case where BPSK is used as the first mapping method as an example.

[0421] For example, in S 1(t) is the t-th modulation symbol of the first modulated symbol stream generated by the mapping unit 1313, and b 1 (t) is the bit mapped to S 1 (t), the modulation symbol S 1 (t) is given by Equation 18.

[0422] [Equation 18]

[0423] S 1 (t) = 2·b 1 (t) - 1 (Equation 18)

[0424] The modulation symbol S 1 (t) can also be given by an equation with the polarity of Equation 18 reversed. The transformation unit 1325 transforms the t-th modulation symbol S 1 (t) of the second modulated symbol stream generated by the mapping unit 1323 into S’ 2 (t) according to Equation 19. 2 (t).

[0425] [Equation 19]

[0426] S′ 2 (t) = -sgn(S 1 (t))·Re[S 2 (t)] + i·Im[S 2 (t)] (Equation 19)

[0427] Here, i is the imaginary unit. In addition, S’ 2 (t) is the t-th modulation symbol of the transformed second modulated symbol stream. In addition, Re[S 2 (t)] is the value of the real part of S 2 (t), and Im[S 2 (t)] is the value of the imaginary part of S 2 (t). In addition, sgn(S 1 (t)) is the polarity of S 1 (t).

[0428] The modulation symbol S’ 2 (t) can also be given by an equation with the polarity of one or both of the real part and the imaginary part of Equation 19 reversed. In addition, the transformation based on Equation 19 is substantially the same as the transformation based on Equation 17.

[0429] As described above, the polarity of the real part of the second modulation symbol is controlled according to the first modulation symbol superimposed on the second modulation symbol. In addition, the polarity of the real part of the second modulation symbol can also be determined according to the value of the bit mapped to the first modulation symbol superimposed on the second modulation symbol.

[0430] In addition, in the above, superposition coding is applied to the real part. That is, the first modulation symbol is composed of a real component, and the real component of the first modulation symbol and the real component of the second modulation symbol are superimposed onto one real component. However, superposition coding can also be applied to the imaginary part. That is, it can also be that the first modulation symbol is composed of an imaginary component, and the imaginary component of the first modulation symbol and the imaginary component of the second modulation symbol are superimposed onto one imaginary component.

[0431] Figure 26 FIG. 14 shows an example of the structure of a transmission device 1400 that multiplexes two data sequences onto two layers and transmits them using modified superposition coding. The structure of the transmission device 1400 is different from the structures of the transmission devices 1200 and 1300. Refer to Figure 26 to describe the structure and operation of the transmission device 1400.

[0432] The transmission device 1400 includes an encoding unit 1411, an interleaving unit 1412, a mapping unit 1413, a multiplication unit 1414, an encoding unit 1421, an interleaving unit 1422, a mapping unit 1423, a multiplication unit 1424, an addition unit 1430, and an RF unit 1440. Each structural element can be a dedicated or general-purpose circuit. The multiplication unit 1414, the multiplication unit 1424, and the addition unit 1430 can also be collectively represented as a superposition unit. The RF unit 1440 can also be represented as a transmission unit. The RF unit 1440 may also include an antenna. The mapping unit 1423 may also include a transformation unit.

[0433] The encoding unit 1411 encodes the input first data sequence based on a first error control coding method to generate a first bit stream. The interleaving unit 1412 sorts the bit order of the first bit stream generated by the encoding unit 1411 based on a first sorting rule. This sorting is also referred to as interleaving.

[0434] The mapping unit 1413 performs a mapping process on the first bit stream sorted by the interleaving unit 1412 according to a first mapping method to generate a first modulation symbol stream composed of a plurality of first modulation symbols. In the mapping process according to the first mapping method, the mapping unit 1413 maps the first bit stream in bit groups of every first number of bits to one of the plurality of signal points in the first constellation according to the value of the bit group.

[0435] The encoding unit 1421 encodes the input second data sequence based on a second error control coding method to generate a second bit stream. The interleaving unit 1422 sorts the bit order of the second bit stream generated by the encoding unit 1421 based on a second sorting rule. This sorting is also referred to as interleaving.

[0436] The mapping unit 1423 transforms (deforms) the second mapping method according to the first bit stream mapped to the first modulated symbol stream by the mapping unit 1413. Then, the mapping unit 1423 performs a mapping process on the second bit stream sorted by the interleaving unit 1422 according to the second mapping method transformed according to the first bit stream. Thus, the mapping unit 1423 generates a second modulated symbol stream composed of a plurality of second modulated symbols.

[0437] In the mapping process according to the second mapping method, the mapping unit 1423 maps the second bit stream in groups of every second bit to one of the plurality of signal points in the second constellation according to the value of the bit group.

[0438] The multiplication unit 1414 multiplies the first modulated symbol of the first modulated symbol stream by the first amplitude coefficient a 1 . The multiplication unit 1424 multiplies the real part of the second modulated symbol of the second modulated symbol stream by the second amplitude coefficient a 2 .

[0439] The multiplication unit 1424 can multiply both the real part and the imaginary part of the second modulated symbol by the second amplitude coefficient a 2 , or can multiply only one of them by the second amplitude coefficient a 2 . Alternatively, the multiplication unit 1424 can multiply the real part and the imaginary part of the second modulated symbol by different amplitude coefficients.

[0440] For example, when the first modulated symbol is composed of only the real part, the multiplication unit 1424 can also multiply only the real part of the second modulated symbol by the second amplitude coefficient a 2 . The multiplication unit 1424 can either not multiply the imaginary part of the second modulated symbol by an amplitude coefficient or multiply it by an amplitude coefficient smaller than the second amplitude coefficient a 2 .

[0441] The addition unit 1430 superimposes the first modulated symbol multiplied by the first amplitude coefficient a 1 and the second modulated symbol whose real part is multiplied by the second amplitude coefficient a 2 to generate a superimposed modulated symbol stream composed of a plurality of superimposed modulated symbols.

[0442] The RF unit 1440 transmits the generated superimposed modulated symbol stream as a signal. Specifically, the RF unit 1440 generates a radio frequency band signal as a signal corresponding to the superimposed modulated symbol stream based on the superimposed modulated symbol stream generated by the addition unit 1430 and transmits the radio frequency band signal from the antenna.

[0443] That is, the superposition unit composed of the multiplication unit 1414, the multiplication unit 1424, and the addition unit 1430 generates a multiplexed signal, which is a signal in which the first data sequence and the second data sequence are multiplexed, by superposing the first modulated symbol stream and the second modulated symbol stream at a specified amplitude ratio. Then, the RF unit 1440 transmits the multiplexed signal. In addition, the multiplexed signal corresponds to the superposed modulated symbol stream.

[0444] In addition, the specified amplitude ratio can be equal (e.g., 1:1), or the multiplication process can be omitted. Further, in the superposition of the first modulated symbol stream and the second modulated symbol stream, an amplitude ratio composed of the ratio of the first modulated symbol stream, the ratio of the real component of the second modulated symbol stream, and the ratio of the imaginary component of the second modulated symbol stream can be used as the specified amplitude ratio. Moreover, the ratio of the component that the first modulated symbol stream does not have in either the real component or the imaginary component can be made larger. In addition, the ratio can also be expressed as a weight.

[0445] The operation of the mapping unit 1423 will be described by taking the case where BPSK is used as the first mapping method as an example.

[0446] For example, in S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 1413, and b 1 (t) is the bit mapped to S 1 (t), the modulated symbol S 1 (t) is given by Equation 20.

[0447] [Equation 20]

[0448] S 1 (t) = 2·b 1 (t) - 1 (Equation 20)

[0449] The modulated symbol stream S 1 (t) can also be given by an equation in which the polarity of Equation 20 is reversed. The mapping unit 1423 performs an exclusive OR logic operation on b 1 (t) for the bits in the second bit stream input from the interleaving unit 1422 that contribute most to the real part of the second constellation. Then, based on the second constellation, the second bit stream on which the exclusive OR logic operation has been performed is mapped.

[0450] Here, the bit that contributes most to the real part of the second constellation means, for example, a bit whose polarity of the real part of the second constellation is reversed when the value of the bit is reversed from 0 to 1 or from 1 to 0. That is, the bit that contributes most to the real part of the second constellation means, for example, a bit whose sign of the positive and negative of the value of the real part in the modulated symbol is reversed when the value of the bit is reversed from 0 to 1 or from 1 to 0.

[0451] In the above, the mapping unit 1423 substantially transforms the second mapping method (second constellation) by transforming the second bit stream. However, the mapping unit 1423 may also directly transform the second mapping method (second constellation) without transforming the second bit stream. That is, the mapping unit 1423 may also transform the correspondence between the bit groups and the signal points in the second constellation.

[0452] In addition, the transformation performed by the mapping unit 1423 may also be performed by a transformation unit included in the mapping unit 1423.

[0453] As described above, the polarity of the real part of the second modulation symbol is controlled according to the value of the bit of the first modulation symbol mapped to be superimposed on the second modulation symbol. In addition, the polarity of the real part of the second modulation symbol may also be controlled according to the first modulation symbol superimposed on the second modulation symbol.

[0454] In addition, in the above, superposition coding is performed on the real part. That is, the first modulation symbol is composed of a real component, and the real component of the first modulation symbol and the real component of the second modulation symbol are superimposed on one real component. However, superposition coding may also be performed on the imaginary part. That is, it may also be that the first modulation symbol is composed of an imaginary component, and the imaginary component of the first modulation symbol and the imaginary component of the second modulation symbol are superimposed on one imaginary component.

[0455] <Successive Decoding of Signals Obtained by Modified Superposition Coding>

[0456] Figure 27 An example of the structure of a receiving device 1500 that can receive a signal formed by multiplexing two data sequences into two layers using the above-described modified superposition coding and perform successive decoding to obtain both or one of the two multiplexed data sequences is shown. Refer to Figure 27 to describe the structure and operation of the receiving device 1500.

[0457] The receiving device 1500 includes an RF unit 1530, a demapping unit 1511, a deinterleaving unit 1512, a decoding unit 1513, an encoding unit 1514, an interleaving unit 1515, a mapping unit 1516, a multiplication unit 1517, a delay unit 1518, a subtraction unit 1519, a transformation unit 1520, a demapping unit 1521, a deinterleaving unit 1522, and a decoding unit 1523. Each structural element may be a dedicated or general-purpose circuit.

[0458] The demapping unit 1511, deinterleaving unit 1512, decoding unit 1513, encoding unit 1514, interleaving unit 1515, mapping unit 1516, multiplication unit 1517, delay unit 1518, subtraction unit 1519, transformation unit 1520, demapping unit 1521, deinterleaving unit 1522, and decoding unit 1523 may also be collectively represented as a derivation unit. The RF unit 1530 may also be represented as a receiving unit. The RF unit 1530 may also include an antenna.

[0459] The receiving device 1500 receives the multiplexed signal transmitted from the transmitting devices 1200, 1300, or 1400 using an antenna and inputs it to the RF unit 1530. That is, the RF unit 1530 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1530 is also represented as a received signal, corresponding to a superimposed modulation symbol stream formed by multiplexing a first modulation symbol stream and a second modulation symbol stream. The RF unit 1530 generates a baseband received signal based on the received signal in the radio frequency band.

[0460] The demapping unit 1511 demaps the baseband received signal based on the first constellation of the first mapping method to generate a first likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0461] The deinterleaving unit 1512 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1513 uses the first likelihood stream sorted by the deinterleaving unit 1512 to perform decoding processing based on the first error control coding method and outputs the decoding result as a first data sequence.

[0462] Here, the demapping unit 1511 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise) and performs demapping based on the first constellation of the first mapping method.

[0463] When only the first data sequence is the acquisition target, the receiving device 1500 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 1500 performs the following process to acquire the second data sequence.

[0464] The encoding unit 1514 encodes the first data sequence obtained by the decoding unit 1513 based on the first error control coding method to generate a first bit stream. The interleaving unit 1515 sorts the bit order of the first bit stream generated by the encoding unit 1514 based on the first sorting rule. This sorting is also referred to as interleaving.

[0465] The mapping unit 1516 performs a mapping process according to the first mapping method on the first bit stream sorted by the interleaving unit 1515, and generates a first modulated symbol stream composed of a plurality of first modulated symbols. The multiplication unit 1517 multiplies the first modulated symbol stream output by the mapping unit 1516 by the first amplitude coefficient a 1 .

[0466] The delay unit 1518 delays the received signal output from the RF unit 1530 during the period from when the baseband received signal is output from the RF unit 1530 to when the reproduced first modulated symbol stream is output by the multiplication unit 1517.

[0467] The subtraction unit 1519 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 1517 from the received signal delayed by the delay unit 1518 1 . Thus, the subtraction unit 1519 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 1519 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream.

[0468] The transformation unit 1520 uses the first bit stream reproduced through coding and interleaving, etc., to perform a transformation on the signal output from the subtraction unit 1519 as the signal corresponding to the second modulated symbol stream. The demapping unit 1521 demaps the signal output by the transformation unit 1520 based on the second constellation of the second mapping method, and generates a second likelihood stream. For example, the amplitude coefficient a is reflected in the second constellation used for demapping 2 .

[0469] The deinterleaving unit 1522 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also called deinterleaving. The decoding unit 1523 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 1522, and outputs the decoding result as the second data sequence.

[0470] Taking the case where BPSK is used as the first mapping method as an example, the operation of the transformation unit 1520 is described.

[0471] For example, when S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 1516, and b 1 (t) is the bit mapped to S 1 (t), the modulated symbol S 1 (t) is given by Equation 21.

[0472] [Equation 21]

[0473] S1 b(t) = 2·b 1 b(t) - 1 (Equation 21)

[0474] The modulation symbol S can also be given by an equation in which the polarity of Equation 21 is reversed 1 b(t). Based on b(t) as in Equation 22, the transformation unit 1520 1 transforms the signal S(t) corresponding to the t-th modulation symbol of the second modulation symbol stream in the signal output from the subtraction unit 1519 2 into S'(t). 2 (t).

[0475] [Equation 22]

[0476]

[0477] Here, i is the imaginary unit. In addition, S'(t) is the transformed signal. In addition, Re[S(t)] is the value of the real part of S(t), and Im[S(t)] is the value of the imaginary part of S(t). The transformed signal S'(t) can also be given by an equation in which the polarity of one or both of the real part and the imaginary part of Equation 22 is reversed 2 (t). 2 (t)] is S 2 (t), and Im[S 2 (t)] is S 2 (t). 2 (t).

[0478] Through the above, the receiving device 1500 obtains one or both of the first data sequence and the second data sequence from the signal received by the antenna. In addition, in the above, superposition coding is performed on the real part. However, superposition coding can also be performed on the imaginary part

[0479] Figure 28 An example of the structure of the receiving device 1600 that can receive a signal formed by multiplexing two data sequences into two layers using the above-described modified superposition coding and perform successive decoding to obtain one or both of the multiplexed two data sequences is shown. The structure of the receiving device 1600 is different from the structure of the receiving device 1500. Refer to Figure 28 to describe the structure and operation of the receiving device 1600

[0480] The receiving device 1600 includes an RF unit 1630, a demapping unit 1611, a deinterleaving unit 1612, a decoding unit 1613, an encoding unit 1614, an interleaving unit 1615, a mapping unit 1616, a multiplication unit 1617, a delay unit 1618, a subtraction unit 1619, a transformation unit 1620, a demapping unit 1621, a deinterleaving unit 1622, and a decoding unit 1623. Each structural element can be a dedicated or general-purpose circuit

[0481] The demapping unit 1611, deinterleaving unit 1612, decoding unit 1613, encoding unit 1614, interleaving unit 1615, mapping unit 1616, multiplication unit 1617, delay unit 1618, subtraction unit 1619, transformation unit 1620, demapping unit 1621, deinterleaving unit 1622, and decoding unit 1623 may also be collectively represented as a derivation unit. The RF unit 1630 may also be represented as a receiving unit. The RF unit 1630 may also include an antenna.

[0482] The receiving device 1600 receives the multiplexed signal transmitted from the transmitting devices 1200, 1300, or 1400 using an antenna and inputs it to the RF unit 1630. That is, the RF unit 1630 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1630 is also represented as a received signal, corresponding to a superimposed modulation symbol stream formed by multiplexing a first modulation symbol stream and a second modulation symbol stream. The RF unit 1630 generates a baseband received signal based on the received signal in the radio frequency band.

[0483] The demapping unit 1611 demaps the baseband received signal based on the first constellation of the first mapping method to generate a first likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0484] The deinterleaving unit 1612 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1613 uses the first likelihood stream sorted by the deinterleaving unit 1612 to perform decoding processing based on the first error control coding method and outputs the decoding result as a first data sequence.

[0485] Here, the demapping unit 1611 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise) and demaps it based on the first constellation of the first mapping method.

[0486] When only the first data sequence is the acquisition target, the receiving device 1600 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 1600 performs the following process to acquire the second data sequence.

[0487] The encoding unit 1614 encodes the first data sequence obtained by the decoding unit 1613 based on the first error control coding method to generate a first bit stream. The interleaving unit 1615 sorts the bit order of the first bit stream generated by the encoding unit 1614 based on the first sorting rule. This sorting is also referred to as interleaving.

[0488] The mapping unit 1616 performs mapping processing on the first bit stream sorted by the interleaving unit 1615 according to the first mapping method, and generates a first modulated symbol stream composed of a plurality of first modulated symbols. The multiplication unit 1617 multiplies the first modulated symbol stream output by the mapping unit 1616 by the first amplitude coefficient a 1 .

[0489] The delay unit 1618 delays the received signal output from the RF unit 1630 during the period from when the baseband received signal is output from the RF unit 1630 to when the reproduced first modulated symbol stream is output by the multiplication unit 1617.

[0490] The subtraction unit 1619 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 1617 from the received signal delayed by the delay unit 1618 1 . Thus, the subtraction unit 1619 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 1619 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream.

[0491] The transformation unit 1620 uses the first modulated symbol stream reproduced through coding, interleaving, and mapping, etc., to perform transformation on the signal output from the subtraction unit 1619 as the signal corresponding to the second modulated symbol stream. The demapping unit 1621 demaps the signal output by the transformation unit 1620 based on the second constellation of the second mapping method, and generates a second likelihood stream. For example, the amplitude coefficient a is reflected in the second constellation used for demapping 2 .

[0492] The deinterleaving unit 1622 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also called deinterleaving. The decoding unit 1623 performs decoding processing on the second likelihood stream sorted by the deinterleaving unit 1622 based on the second error control coding method, and outputs the decoding result as the second data sequence.

[0493] Taking the case where BPSK is used as the first mapping method as an example, the operation of the transformation unit 1620 is described.

[0494] For example, when S 1 (t) is the t-th modulated symbol of the first modulated symbol stream generated by the mapping unit 1616, and b 1 (t) is the bit mapped to S 1 (t), the modulated symbol S 1 (t) is given by Equation 23.

[0495] [Equation 23]

[0496] S 1 S(t) = 2·b 1 S(t)-1 (Equation 23)

[0497] The modulation symbol S can also be given by an equation with the polarity of Equation 23 reversed 1 S(t). Based on the modulation symbol S as in Equation 24, the transformation unit 1620 1 transforms the signal S(t) corresponding to the t-th modulation symbol of the second modulation symbol stream in the signal output from the subtraction unit 1619 2 into S'(t). 2 (t).

[0498] [Equation 24]

[0499] S′ 2 S'(t) = -sgn(S 1 (t))·Re[S 2 (t)] + i·Im[S 2 (t)] (Equation 24)

[0500] Here, i is the imaginary unit. In addition, S'(t) is the transformed signal. Also, Re[S 2 (t)] is the value of the real part of S 2 (t), Im[S 2 (t)] is the value of the imaginary part of S 2 (t). Also, sgn(S 2 (t)) is the polarity of S 1 (t). The transformed signal S'(t) can also be given by an equation with the polarity of one or both of the real part and the imaginary part of Equation 24 reversed 1 (t). In addition, the transformation based on Equation 24 is substantially the same as the transformation based on Equation 22 2 (t).

[0501] Through the above, the receiving device 1600 obtains both or one of the first data sequence and the second data sequence from the signal received by the antenna. In addition, in the above, superposition coding is performed on the real part, but superposition coding can also be performed on the imaginary part

[0502] Figure 29 An example of the structure of the receiving device 1700 that represents receiving a signal multiplexed with two data sequences into two layers using the above-mentioned modified superposition coding and performing successive decoding to be able to obtain both or one of the two multiplexed data sequences is shown. The structure of the receiving device 1700 is different from the structures of the receiving devices 1500 and 1600. Refer to Figure 29 to describe the structure and operation of the receiving device 1700

[0503] The receiving device 1700 includes an RF unit 1730, a demapping unit 1711, a deinterleaving unit 1712, a decoding unit 1713, an encoding unit 1714, an interleaving unit 1715, a mapping unit 1716, a multiplication unit 1717, a delay unit 1718, a subtraction unit 1719, a demapping unit 1721, a deinterleaving unit 1722, and a decoding unit 1723. Each structural element may be a dedicated or general-purpose circuit.

[0504] The demapping unit 1711, the deinterleaving unit 1712, the decoding unit 1713, the encoding unit 1714, the interleaving unit 1715, the mapping unit 1716, the multiplication unit 1717, the delay unit 1718, the subtraction unit 1719, the demapping unit 1721, the deinterleaving unit 1722, and the decoding unit 1723 may also be collectively represented as a derivation unit. The RF unit 1730 may also be represented as a receiving unit. The RF unit 1730 may also include an antenna. The demapping unit 1721 may also include a transformation unit.

[0505] The receiving device 1700 receives the multiplexed signal transmitted from the transmitting devices 1200, 1300, or 1400 using an antenna and inputs it to the RF unit 1730. That is, the RF unit 1730 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1730 is also represented as a received signal, corresponding to a superimposed modulation symbol stream formed by multiplexing a first modulation symbol stream and a second modulation symbol stream. The RF unit 1730 generates a baseband received signal based on the received signal in the radio frequency band.

[0506] The demapping unit 1711 demaps the baseband received signal based on the first constellation of the first mapping method, generating a first likelihood stream. For example, an amplitude coefficient a is reflected in the first constellation used for demapping. 1 .

[0507] The deinterleaving unit 1712 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1713 uses the first likelihood stream sorted by the deinterleaving unit 1712 to perform decoding processing based on the first error control coding method, and outputs the decoding result as a first data sequence.

[0508] Here, the demapping unit 1711 processes the component corresponding to the second modulation symbol of the second data sequence in the received signal corresponding to the superimposed modulation symbol stream as an unknown signal (noise), and performs demapping based on the first constellation of the first mapping method.

[0509] When only the first data sequence is the acquisition target, the receiving device 1700 ends the process at the time point when the estimation of the first data sequence is completed. On the other hand, when the second data sequence is also the acquisition target in addition to the first data sequence, or when only the second data sequence is the acquisition target, the receiving device 1700 performs the following process to acquire the second data sequence.

[0510] The encoding unit 1714 encodes the first data sequence acquired by the decoding unit 1713 based on the first error control coding method to generate the first bit stream. The interleaving unit 1715 sorts the bit order of the first bit stream generated by the encoding unit 1714 based on the first sorting rule. This sorting is also called interleaving.

[0511] The mapping unit 1716 performs mapping processing on the first bit stream sorted by the interleaving unit 1715 according to the first mapping method to generate a first modulated symbol stream composed of a plurality of first modulated symbols. The multiplication unit 1717 multiplies the first modulated symbol stream output by the mapping unit 1716 by the first amplitude coefficient a 1 .

[0512] The delay unit 1718 delays the received signal output from the RF unit 1730 during the period from when the baseband received signal is output from the RF unit 1730 to when the reproduced first modulated symbol stream is output by the multiplication unit 1717.

[0513] The subtraction unit 1719 subtracts the first modulated symbol stream multiplied by the first amplitude coefficient a by the multiplication unit 1717 from the received signal delayed by the delay unit 1718. 1 Thus, the subtraction unit 1719 removes the component corresponding to the first modulated symbol from the received signal superimposed with the component corresponding to the first modulated symbol, the component corresponding to the second modulated symbol, and noise. Then, the subtraction unit 1719 outputs the signal superimposed with the component corresponding to the second modulated symbol and noise as the signal corresponding to the second modulated symbol stream.

[0514] The demapping unit 1721 demaps the signal output from the subtraction unit 1719 as the signal corresponding to the second modulated symbol stream based on the second constellation of the second mapping method to generate a second likelihood stream. At this time, the first bit stream reproduced through encoding and interleaving is reflected in this process. In addition, for example, the amplitude coefficient a is reflected in the second constellation used for demapping. 2 .

[0515] The deinterleaving unit 1722 sorts the second likelihood stream based on the sorting rule opposite to the second sorting rule. This sorting is also called deinterleaving. The decoding unit 1723 performs a decoding process on the second likelihood stream sorted by the deinterleaving unit 1722 based on the second error control coding method and outputs the decoding result as the second data sequence.

[0516] Taking the case of using BPSK as the first mapping method as an example, the operation of the demapping unit 1721 will be described.

[0517] For example, in S 1 (t) is the t-th modulation symbol of the first modulated symbol stream generated by the mapping unit 1716, and b 1 (t) is the bit mapped to S 1 (t), the modulation symbol S 1 (t) is given by Equation 25.

[0518] [Equation 25]

[0519] S 1 (t) = 2·b 1 (t) - 1 (Equation 25)

[0520] The modulation symbol S 1 (t) can also be given by an equation with the polarity of Equation 25 reversed. The demapping unit 1721 demaps the signal S 2 (t) output from the subtraction unit 1719 as the signal corresponding to the t-th modulation symbol of the second modulated symbol stream based on the second constellation of the second mapping method.

[0521] The demapping unit 1721 performs an inversion process corresponding to b 1 (t) on the bit likelihood stream obtained through demapping for the bit likelihood corresponding to the bit that contributes most to the real part of the second constellation. For example, the demapping unit 1721 performs an exclusive OR logic operation of b 1 (t) on the bit likelihood corresponding to the bit that contributes most to the real part of the second constellation in the bit likelihood stream obtained through demapping.

[0522] The demapping unit 1721 outputs the bit likelihood stream after performing the above inversion process as the second bit likelihood stream.

[0523] In the above, the demapping unit 1721 substantially transforms the second mapping method (second constellation) by transforming the bit likelihood stream. However, the demapping unit 1721 can also directly transform the second mapping method (second constellation) without transforming the bit likelihood stream. That is, the demapping unit 1721 can also transform the correspondence between the bit groups and the signal points in the second constellation.

[0524] In addition, the transformation performed by the demapping unit 1721 can also be performed by a transformation unit included in the demapping unit 1721.

[0525] As described above, the receiving apparatus 1700 obtains one or both of the first data sequence and the second data sequence from the signal received by the antenna. Further, in the above, the real part is subjected to superposition coding. However, superposition coding may also be performed on the imaginary part.

[0526] <Parallel Decoding of Signals Obtained by Modified Superposition Coding>

[0527] Next, a receiving method for parallel decoding of a signal obtained by the modified superposition coding in the present embodiment will be described. The structure of the transmitting apparatus is the same as that of the transmitting apparatus 1200 shown in Figure 24 the transmitting apparatus 1200 shown in Figure 25 the transmitting apparatus 1300 shown in Figure 26 or the transmitting apparatus 1400 shown in, and thus the description thereof will be omitted. In the parallel decoding in the modified superposition coding, the receiving apparatus does not remove the component of the modulated symbol stream of the first layer included in the received signal, but treats the component of the modulated symbol stream of the first layer as an unknown signal (noise) and decodes the second layer.

[0528] Figure 30 FIG. shows an example of the structure of a receiving apparatus 1800 that receives a signal in which two data sequences are multiplexed into two layers using modified superposition coding and performs parallel decoding to be able to obtain one or both of the two multiplexed data sequences. Referring to Figure 30 the structure and operation of the receiving apparatus 1800 will be described.

[0529] The receiving apparatus 1800 includes an RF unit 1830, a demapping unit 1810, an interleaving unit 1812, a decoding unit 1813, an interleaving unit 1822, and a decoding unit 1823. Each structural element may be a dedicated or general-purpose circuit. The demapping unit 1810, the interleaving unit 1812, the decoding unit 1813, the interleaving unit 1822, and the decoding unit 1823 may also be collectively represented as a derivation unit. The RF unit 1830 may also be represented as a receiving unit. The RF unit 1830 may also include an antenna.

[0530] The receiving apparatus 1800 receives the multiplexed signal transmitted from the transmitting apparatus 1200, 1300, or 1400 using the antenna and inputs it to the RF unit 1830. That is, the RF unit 1830 receives the multiplexed signal via the antenna. The multiplexed signal received by the RF unit 1830 may also be represented as a received signal. The RF unit 1830 generates a baseband received signal based on the wireless band received signal.

[0531] The demapping unit 1810 demaps the received signal in the baseband to generate a first likelihood stream and a second likelihood stream. The demapping unit 1810 demaps, for example, based on a deformed superposition constellation representing the configuration of signal points of a superposition modulation symbol formed by superposing a first modulation symbol and a second modulation symbol using deformed superposition coding.

[0532] The deformed superposition constellation is determined according to a first constellation of a first mapping method, a second constellation of a second mapping method, a first amplitude coefficient a 1 and a second amplitude coefficient a 2 and the like.

[0533] Figure 31 An example of a constellation representing BPSK is shown. Specifically, in a complex plane where the horizontal axis is the real part (real component) and the vertical axis is the imaginary part (imaginary component), two signal points of BPSK are plotted. In addition, BPSK refers to binary phase shift keying.

[0534] For example, in BPSK, based on Figure 31 the constellation shown, a bit (0 or 1) is associated with a complex modulation symbol. In this example, the bit is associated with a complex modulation symbol whose imaginary part is 0. That is to say, in this example, substantially the bit is associated with a real modulation symbol.

[0535] Figure 32 An example of a deformed superposition constellation corresponding to deformed superposition coding is shown. Specifically, Figure 31 the constellation of BPSK shown is combined with Figure 5 the constellation of Nu-256QAM shown.

[0536] More specifically, according to the two signal points of the constellation of BPSK, the constellation of Nu-256QAM (256 signal points) is arranged in each of the two regions in the complex plane. These two regions corresponding to the constellation of Nu-256QAM may also partially overlap. Moreover, the transformation of the second modulation symbol stream is reflected in this deformed superposition constellation.

[0537] For example, when combining the constellation of Nu-256QAM with the signal point having a positive real part among the two signal points of the constellation of BPSK, the polarity of the real part of the constellation of Nu-256QAM is inverted. Specifically, Figure 32 shows a first signal point, a second signal point, and a third signal point. When the polarity of the real part of the constellation of Nu-256QAM is not inverted, the first signal point and the third signal point correspond to the same bit value for the second bit stream.

[0538] In the case of polarity inversion of the real part of the constellation of Nu-256QAM, the first signal point and the second signal point correspond to the same bit value for the second bit stream. That is, a plurality of signal points corresponding to the same bit value for the second bit stream approach each other by inversion and are thus concentrated. Thereby, the influence on demapping due to noise is suppressed.

[0539] The demapping unit 1810 demaps based on Figure 32 the modified superposition constellation shown. That is, the demapping unit 1810 generates a first likelihood stream in a state where the modulated symbol stream of the second layer is unknown, and generates a second likelihood stream in a state where the modulated symbol stream of the first layer is unknown.

[0540] In addition, the demapping unit 1810 may use the first constellation of the first mapping method in the generation of the first likelihood stream, and use the above-mentioned modified superposition constellation in the generation of the second likelihood stream.

[0541] When the demapping unit 1810 uses the first constellation in the generation of the first likelihood stream, the number of signal points considered in the generation of the first likelihood stream can be reduced compared to the case where the modified superposition constellation is also used in the generation of the first likelihood stream. Therefore, in this case, the demapping unit 1810 can reduce the amount of computation.

[0542] Alternatively, for example, the demapping unit 1810 corresponds to: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal. The demapping unit 1810 may also include: a first demapping unit that generates a first likelihood stream by demapping the received signal; and a second demapping unit that generates a second likelihood stream by demapping the received signal.

[0543] Alternatively, the demapping unit 1810 may transform the second likelihood stream generated using the superposition constellation instead of the modified superposition constellation according to the first likelihood stream. Thereby, the demapping unit 1810 can obtain the same second likelihood stream as the second likelihood stream generated using the modified superposition constellation.

[0544] Alternatively, the demapping unit 1810 may transform the multiplexed signal without using the modified superposition constellation, thereby obtaining the same second likelihood stream as the second likelihood stream generated using the modified superposition constellation.

[0545] The deinterleaving unit 1812 sorts the first likelihood stream based on a sorting rule opposite to the first sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1813 performs a decoding process based on the first error control coding method on the first likelihood stream sorted by the deinterleaving unit 1812, and outputs the decoding result as the first data sequence.

[0546] The deinterleaving unit 1822 sorts the second likelihood stream based on a sorting rule that is the reverse of the second sorting rule. This sorting is also referred to as deinterleaving. The decoding unit 1823 performs a decoding process based on the second error control coding method on the second likelihood stream sorted by the deinterleaving unit 1822. The decoding result is output as the second data sequence.

[0547] Through the above, the receiving device 1800 obtains either or both of the first data sequence and the second data sequence from the signal received by the antenna. In addition, in the above, the real part has been subjected to superposition coding. However, superposition coding may also be performed on the imaginary part.

[0548] In addition, in the transmitting devices 1200, 1300, and 1400 and the receiving devices 1500, 1600, 1700, and 1800, similar to Embodiment 1, sorting (interleaving and deinterleaving) may also be omitted. That is, each interleaving unit and each deinterleaving unit are optional structural elements and may not be included in these devices.

[0549] However, interleaving and deinterleaving form a pair. Therefore, basically, when the transmitting devices 1200, 1300, and 1400 include each interleaving unit, the receiving devices 1500, 1600, 1700, and 1800 include each deinterleaving unit and each interleaving unit. On the other hand, when the transmitting devices 1200, 1300, and 1400 do not include each interleaving unit, the receiving devices 1500, 1600, 1700, and 1800 do not include each deinterleaving unit and each interleaving unit.

[0550] In addition, in the receiving devices 1500, 1600, and 1700, the amplitude coefficient a may also be reflected in the mapping for generating the first modulation symbol. 1 In this case, the multiplication process of the amplitude coefficient a may also be omitted. 1 Moreover, the receiving devices 1500, 1600, and 1700 may not separately include the multiplication units 1517, 1617, and 1717.

[0551] In addition, the error control coding of the first data sequence and the second data sequence may also be performed by an external device. In this case, in the transmitting devices 1200, 1300, and 1400, the error control coding may also be omitted. Moreover, the transmitting devices 1200, 1300, and 1400 may not include the coding units 1211, 1221, 1311, 1321, 1411, and 1421.

[0552] In addition, as described above, superposition coding can be performed on the real part, or on the imaginary part. Also, superposition coding can be performed on a specified direction in the complex plane. For example, in the orthogonal coordinate system of the real axis and the imaginary axis, superposition coding can also be performed on an inclined direction.

[0553] Specifically, it can also be that the first modulation symbol has a component in a first direction in the complex plane, and the second modulation symbol has a component in the first direction and a component in a second direction perpendicular to the first direction. Moreover, it can also be that the component of the first modulation symbol in the first direction and the component of the second modulation symbol in the first direction are superimposed on one component in the first direction. In this case, for example, the polarity of the component of the second modulation symbol in the first direction is controlled according to the component of the first modulation symbol in the first direction.

[0554] That is to say, in the content described herein, the real component can be replaced by the imaginary component, or by the component in a first direction as a direction in the complex plane, or by the component in a second direction perpendicular to the first direction. In addition, the imaginary component can be replaced by the real component, or by the component in a first direction as a direction in the complex plane, or by the component in a second direction perpendicular to the first direction.

[0555] For example, the component of the modulation symbol in the first direction includes a real part and an imaginary part. By inverting the polarity of this component, the polarities of both the real part and the imaginary part of this component are inverted. In addition, regarding the polarity of this component, it can be determined according to the polarity of the real part of this component, or according to the polarity of the imaginary part of this component.

[0556] That is, it can also be determined in the following manner: when the polarity of the real part of this component is positive, the polarity of this component is positive; when the polarity of the real part of this component is negative, the polarity of this component is negative. Or, it can also be determined in the following manner: when the polarity of the imaginary part of this component is positive, the polarity of this component is positive; when the polarity of the imaginary part of this component is negative, the polarity of this component is negative.

[0557] Also, the direction of the real axis can be either the first direction or the second direction perpendicular to the first direction. The direction of the imaginary axis can be either the first direction or the second direction perpendicular to the first direction.

[0558] The first constellation of the first mapping method can also have a plurality of signal points dispersed only in the first direction. Moreover, the second constellation of the second mapping method can also have a plurality of signal points dispersed in both the first direction and the second direction.

[0559] The first mapping method is not limited to BPSK. A constellation having three or more signal points may also be used as the first constellation of the first mapping method. For example, a constellation having three or more signal points on a straight line in the complex plane may also be used as the first constellation of the first mapping method.

[0560] Between two adjacent signal points on a straight line in the first direction in the first constellation of the first mapping method, the polarity of the second mapping method for the first direction is inverted. That is, the inversion is performed in such a manner that the polarity of the first direction is different between the second modulation symbol superimposed on the first modulation symbol corresponding to one of the two signal points and the second modulation symbol superimposed on the first modulation symbol corresponding to the other signal point. Moreover, according to the arrangement order of three or more signal points on the straight line in the first direction, the polarity of the first direction is alternately switched.

[0561] Figure 33 It is a flowchart showing an operation example of the transmission device 1200. First, the mapping unit 1213 generates a first modulation symbol stream of the first data sequence by mapping the first bit stream of the first data sequence (S501). Then, the mapping unit 1223 generates a second modulation symbol stream of the second data sequence by mapping the second bit stream of the second data sequence (S502).

[0562] The transformation unit 1225 gives a transformation corresponding to the first modulation symbol stream only to the second modulation symbol stream with respect to the first direction among the first direction and the second direction. Here, the first direction and the second direction are two directions perpendicular to each other in the complex plane representing the first modulation symbol stream and the second modulation symbol stream.

[0563] Specifically, the transformation unit 1225 gives a transformation corresponding to the first modulation symbol stream to the component of the second modulation symbol stream with respect to the first direction, rather than to the component of the second modulation symbol stream with respect to the second direction. In addition, the transformation unit 1225 gives a transformation corresponding to the first modulation symbol stream to the second modulation symbol stream by transforming the second modulation symbol stream according to the first bit stream.

[0564] Next, the superimposing unit generates a multiplexed signal by superimposing the first modulation symbol stream and the second modulation symbol stream given a transformation corresponding to the first modulation symbol stream at a prescribed amplitude ratio (S504). Here, the superimposing unit is composed of a first multiplication unit 1214, a second multiplication unit 1224, and an addition unit 1230. Then, the RF unit 1240 transmits the generated multiplexed signal (S505).

[0565] In addition, in the above operation example, the transmitting device 1200 gives a transformation corresponding to the first modulation symbol stream to the second modulation symbol stream by transforming the second modulation symbol stream according to the first bit stream (S503). Alternatively, as in the transmitting device 1300, a transformation corresponding to the first modulation symbol stream can be given to the second modulation symbol stream by transforming the second modulation symbol stream according to the first modulation symbol stream.

[0566] Or, as in the transmitting device 1400, the first bit stream can be used to transform the second bit stream or the second mapping method (second constellation) for generating the second modulation symbol stream. Then, thereby, a transformation corresponding to the first modulation symbol stream can also be given to the second modulation symbol stream. In this case, the second bit stream or the second mapping method is transformed before the second modulation symbol stream is generated.

[0567] That is, a transformation corresponding to the first modulation symbol stream can be given to the second modulation symbol stream by transforming the second bit stream, the second mapping method, or the second modulation symbol stream according to the first bit stream or the first modulation symbol stream.

[0568] In addition, the transformation unit 1225 can also control the polarity of the component of each modulation symbol in the second modulation symbol stream with respect to the first direction by giving a transformation corresponding to the first modulation symbol stream to the second modulation symbol stream. Thus, the transformation unit 1225 can also reverse the polarity of the component of the second modulation symbol with respect to the first direction when the component of the first modulation symbol with respect to the first direction satisfies a specified condition.

[0569] The specified condition can be either a condition that the polarity of the component of the first modulation symbol with respect to the first direction is a specified polarity, or a condition that the component of the first modulation symbol with respect to the first direction is within a specified range of 1 or more. The specified range of 1 or more can be either a positive range or a negative range.

[0570] Figure 34 It is a flowchart showing operation examples of the receiving devices 1500, 1600, 1700, and 1800. First, the receiving unit receives the multiplexed signal (S601). Here, the receiving unit is the RF unit 1530 of the receiving device 1500, the RF unit 1630 of the receiving device 1600, the RF unit 1730 of the receiving device 1700, or the RF unit 1830 of the receiving device 1800.

[0571] The multiplexed signal is a signal formed by multiplexing a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer. In addition, this multiplexed signal is a signal formed by superimposing the first modulation symbol stream and the second modulation symbol stream at a specified amplitude ratio.

[0572] The first modulated symbol stream is a modulated symbol stream generated by mapping the first bit stream of the first data sequence. The second modulated symbol stream is a modulated symbol stream generated by mapping the second bit stream of the second data sequence and is given a transformation corresponding to the first modulated symbol stream only with respect to the first direction among the first direction and the second direction in the complex plane.

[0573] Next, the derivation unit derives at least one of the first data sequence and the second data sequence from the multiplexed signal (S602).

[0574] For example, the derivation unit of the receiving device 1500 includes a demapping unit 1511, a deinterleaving unit 1512, a decoding unit 1513, an encoding unit 1514, an interleaving unit 1515, a mapping unit 1516, a multiplication unit 1517, a delay unit 1518, a subtraction unit 1519, a transformation unit 1520, a demapping unit 1521, a deinterleaving unit 1522, and a decoding unit 1523.

[0575] In addition, for example, the derivation unit of the receiving device 1600 includes a demapping unit 1611, a deinterleaving unit 1612, a decoding unit 1613, an encoding unit 1614, an interleaving unit 1615, a mapping unit 1616, a multiplication unit 1617, a delay unit 1618, a subtraction unit 1619, a transformation unit 1620, a demapping unit 1621, a deinterleaving unit 1622, and a decoding unit 1623.

[0576] In addition, for example, the derivation unit of the receiving device 1700 includes a demapping unit 1711, a deinterleaving unit 1712, a decoding unit 1713, an encoding unit 1714, an interleaving unit 1715, a mapping unit 1716, a multiplication unit 1717, a delay unit 1718, a subtraction unit 1719, a demapping unit 1721, a deinterleaving unit 1722, and a decoding unit 1723.

[0577] In addition, for example, the derivation unit of the receiving device 1800 includes a demapping unit 1810, a deinterleaving unit 1812, a decoding unit 1813, a deinterleaving unit 1822, and a decoding unit 1823.

[0578] According to the above operation, a multiplexed signal in which the first modulated symbol stream and the second modulated symbol stream given a transformation corresponding to the first modulated symbol stream with respect to the first direction are superimposed is received. Then, at least one of the first data sequence and the second data sequence is derived from the multiplexed signal. That is, by receiving the multiplexed signal superimposed in a manner that reduces the degradation of performance during parallel decoding, both or one of the first data sequence and the second data sequence can be efficiently derived from the multiplexed signal.

[0579] In Figure 30 the receiving device 1800 performing parallel decoding shown, Figure 27 、 28Compared with the receiving apparatuses 1500, 1600, and 1700 that perform successive decoding as shown in FIGS. 28 and 29, the decoding performance for the second layer deteriorates.

[0580] As described above, the receiving apparatus 1800 that performs parallel decoding in the present embodiment has deteriorated decoding performance related to the second data sequence transmitted in the second layer compared with the receiving apparatuses 1500, 1600, and 1700 that perform successive decoding. However, the structure required for decoding the second layer can be reduced.

[0581] Specifically, in the receiving apparatus 1800, compared with Figure 27 , 28 and the receiving apparatuses 1500, 1600, and 1700 that perform successive decoding as shown in FIGS. 28 and 29, structural elements for reproducing the modulated symbol stream of the first layer are not required. That is, the encoding units 1514, 1614, and 1714, the interleaving units 1515, 1615, and 1715, the mapping units 1516, 1616, and 1716, and the multiplication units 1517, 1617, and 1717 are not required.

[0582] In addition, the delay units 1518, 1618, and 1718 for delaying the received signal and the subtraction units 1519, 1619, and 1719 for removing the components of the modulated symbols of the reproduced first layer from the received signal are not required.

[0583] Therefore, the circuit scale can be reduced. In addition, the receiving apparatus 1800 can reduce the amount of computation compared with the receiving apparatuses 1500, 1600, and 1700, and can reduce the power consumption.

[0584] And, Figure 27 , 28 and the receiving apparatuses 1500, 1600, and 1700 that perform successive decoding as shown in FIGS. 28 and 29 demodulate the first layer of the received signal to obtain the first data sequence, and generate the first modulated symbol stream based on the obtained first data sequence. Moreover, thereafter, the receiving apparatuses 1500, 1600, and 1700 start demodulating the second layer of the received signal to obtain the second data sequence.

[0585] On the other hand, the receiving apparatus 1800 that performs parallel decoding in the present embodiment can perform the acquisition of the first data sequence and the acquisition of the second data sequence in parallel simultaneously, and thus can shorten the processing delay.

[0586] In addition, the receiving apparatus may observe the SNR of the received signal, and switch the decoding process so as to perform parallel decoding when the SNR is high and perform successive decoding when the SNR is low.

[0587] In this case, for example, Figure 27The receiving device 1500 shown includes a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may also be included in the RF unit 1530 or the demapping unit 1521. Moreover, the demapping unit 1521 has a structure that performs, in addition to the demapping process based on the second constellation, the demapping process based on the deformed superposition constellation as described in the operation of the demapping unit 1810 Figure 30 of.

[0588] Then, the demapping unit 1521 switches between the demapping process based on the second constellation for the signal output from the transformation unit 1520 and the demapping process based on the deformed superposition constellation for the signal output from the RF unit 1530. For example, the demapping unit 1521 switches these demapping processes according to a control signal from the control unit.

[0589] In addition, such a structure is also obtained by Figure 11 the receiving device 400 shown, Figure 27 the receiving device 1500 (such as the transformation unit 1520 and the demapping unit 1521) shown, and Figure 30 the receiving device 1800 (such as the demapping unit 1810) shown in combination.

[0590] As another structure, for example, Figure 28 the receiving device 1600 shown includes a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may also be included in the RF unit 1630 or the demapping unit 1621. Moreover, the demapping unit 1621 has a structure that performs, in addition to the demapping process based on the first bitstream and the second constellation, the demapping process based on the deformed superposition constellation as described in the operation of the demapping unit 1810 Figure 30 of.

[0591] Then, the demapping unit 1621 switches between the demapping process based on the second constellation for the signal output from the transformation unit 1620 and the demapping process based on the deformed superposition constellation for the signal output from the RF unit 1630. For example, the demapping unit 1621 switches these demapping processes according to a control signal from the control unit.

[0592] In addition, such a structure is also obtained by Figure 11 the receiving device 400 shown, Figure 28 the receiving device 1600 (such as the transformation unit 1620 and the demapping unit 1621) shown, and Figure 30 the receiving device 1800 (such as the demapping unit 1810) shown in combination.

[0593] As another structure, for example, Figure 29The receiving device 1700 shown includes a control unit that switches between successive decoding and parallel decoding according to the SNR. The control unit may also be included in the RF unit 1730 or the demapping unit 1721. Also, the demapping unit 1721 has a structure that performs, in addition to the demapping process based on the first bit stream and the second constellation, the demapping process based on the deformed superposition constellation as described for the operation of the demapping unit 1810. Figure 30 The structure of the demapping unit 1810.

[0594] Then, the demapping unit 1721 switches between the demapping process based on the second constellation for the signal output from the subtraction unit 1719 and the demapping process based on the deformed superposition constellation for the signal output from the RF unit 1730. For example, the demapping unit 1721 switches these demapping processes according to a control signal from the control unit.

[0595] In addition, such a structure is also obtained by Figure 11 the combination of the receiving device 400 shown, Figure 29 the receiving device 1700 (such as the demapping unit 1721) shown, and Figure 30 the receiving device 1800 (such as the demapping unit 1810) shown.

[0596] In this way, when the SNR is high, the receiving devices 1500, 1600, and 1700 can reduce the amount of computation and cut power consumption by performing parallel decoding. Also, when the SNR is high, the receiving devices 1500, 1600, and 1700 can shorten the processing delay by performing parallel decoding. On the other hand, when the SNR is low, the receiving devices 1500, 1600, and 1700 can increase the possibility of accurately decoding the second data sequence by performing successive decoding.

[0597] In this embodiment, different mapping rules may be used for the real part and the imaginary part of the second mapping method. When superimposed coding is performed on the real part, for the second mapping method, the reception level of the real part is lower than that of the imaginary part. Therefore, in the second mapping method, it is preferable that the noise tolerance of the real part is higher than that of the imaginary part.

[0598] Thus, it is preferable to make the number of values of the mapping of the real part smaller than the number of values of the mapping of the imaginary part. The number of values is also called the modulation number of values. For example, 32-value PAM may be used for the mapping of the real part in the second mapping method, and 64-value PAM may be used for the mapping of the imaginary part.

[0599] In addition, in the case of using a non-uniform constellation in the second constellation of the second mapping method, it is preferable to use a non-uniform constellation corresponding to the SNR where the real part is lower than the imaginary part. For example, a 32-value non-uniform PAM corresponding to an SNR of about 15 dB can be used for the mapping of the real part in the second mapping method, and a 32-value non-uniform PAM corresponding to an SNR of about 20 dB can be used for the mapping of the imaginary part.

[0600] In addition, 32 listed as the multi-value number for the mapping of the real part and 64 listed as the multi-value number for the mapping of the imaginary part are examples, and other values can also be used. For example, a 4-value PAM can be used for the real part and an 8-value PAM can be used for the imaginary part. In addition, a 2-value PAM can be used for the real part and a 4-value PAM can be used for the imaginary part. In addition, a 2-value PAM can be used for the real part and an 8-value PAM can be used for the imaginary part. In this way, any combination of values can be used for the mapping of the real part and the imaginary part.

[0601] In addition, the second data sequence can also be composed of two sequences. Moreover, it can be that the bit stream of one sequence among the two sequences is mapped to the real part, and the bit stream of the other sequence is mapped to the imaginary part. Moreover, it can be that the two bit streams of the two sequences are mapped to the real part and the imaginary part, and a second modulated symbol stream is generated. In this case, PAM that can be used as the modulation method for one axis is effective. In addition, PAM refers to pulse amplitude modulation.

[0602] Figure 35 An example of a constellation based on PAM is shown. Specifically, on the complex plane where the horizontal axis is the real part (real component) and the vertical axis is the imaginary part (imaginary component), multiple signal points based on PAM are plotted. In this example, an 8-value non-uniform PAM is used for the real part and a 16-value non-uniform PAM is used for the imaginary part.

[0603] The constellation shown in Figure 35 can also be used for the second constellation of the second mapping method. That is, a constellation in which more signal points are arranged in the direction of the vertical axis corresponding to the imaginary part than in the direction of the horizontal axis corresponding to the real part can be used as the second constellation of the second mapping method.

[0604] Figure 36 An example of a deformed superposition constellation corresponding to deformed superposition coding is shown. Specifically, Figure 31 the constellation shown in Figure 35 is combined with the constellation shown in

[0605] More specifically, according to two signal points of the constellation of BPSK, each of the two regions configured on the complex plane based on the PAM constellation (128 signal points). These two regions corresponding to the PAM-based constellation may also partially overlap.

[0606] In this example, the first amplitude coefficient a 1 is the positive square root of 0.75, and the second amplitude coefficient a 2 is the positive square root of 0.25. Two constellations are combined based on these amplitude coefficients. In addition, in the superposition coding of this example, the imaginary part of the second modulation symbol stream is not multiplied by the second amplitude coefficient a 2 , and the value of the imaginary part of the signal point included in the second constellation as the PAM-based constellation is maintained.

[0607] In addition, the transformation of the second modulation symbol stream is reflected in this modified superposition constellation. For example, when combining the PAM-based constellation with the signal point having a positive real part among the two signal points of the BPSK constellation, the polarity of the real part of the PAM-based constellation is reversed.

[0608] In addition, in the above second mapping method, the mapping rules for the real part and the imaginary part are respectively based on PAM, but the second mapping method can also be other mapping methods.

[0609] For example, any QAM or any non-uniform QAM with signal point configurations where both the real part and the imaginary part are respectively represented by PAM with arbitrary multi-valued numbers can also be used as the second mapping method. As another example, any non-uniform QAM with signal point configurations where one or both of the real part and the imaginary part are not represented by PAM can also be used as the second mapping method.

[0610] In this case, for example, a signal point configuration where the real part corresponds to an SNR of about 15 dB and the imaginary part corresponds to an SNR of about 20 dB can also be used as the second mapping method. As another example, a signal point configuration where the maximum value of the real component among multiple signal points is less than the maximum value of the imaginary component among multiple signal points can also be used as the second mapping method.

[0611] In the above, superposition coding is performed on the real part, but the processing for the real part and the processing for the imaginary part can be swapped, and superposition coding can also be performed on the imaginary part. That is, it can also be that the first modulation symbol is composed of an imaginary component, and the imaginary components of the first modulation symbol and the second modulation symbol are superimposed into one imaginary component.

[0612] In addition, it is not necessary to assign the transformation corresponding to the first modulation symbol stream to the second modulation symbol stream. That is, the polarity inversion may not be performed, and the polarity may not be controlled. Even if such a transformation is not applied, simple superposition coding can be performed along the real axis, the imaginary axis, or another corresponding direction. Therefore, a more flexible superposition coding can be provided thereby.

[0613] In addition, even if a transformation is not applied, superposition coding is performed more efficiently by using a mapping method or constellation corresponding to the direction of superposition coding.

[0614] As described above, a receiving device in one aspect of the present disclosure receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superposition coding, and derives the plurality of data sequences from the multiplexed signal. The receiving device includes: a receiving unit that receives the multiplexed signal; a first demapping unit that generates a first likelihood stream of the first data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a second modulation symbol stream of the second data sequence as an undetermined signal component; a second demapping unit that generates a second likelihood stream of the second data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a first modulation symbol stream of the first data sequence as an undetermined signal component; a first decoding unit that derives the first data sequence by performing error control decoding on the first likelihood stream; and a second decoding unit that derives the second data sequence by performing error control decoding on the second likelihood stream. The receiving unit receives the multiplexed signal in which the first modulation symbol stream generated by mapping the first bit stream of the first data sequence and the second modulation symbol stream generated by mapping the second bit stream of the second data sequence are superimposed at a predetermined amplitude ratio. The second modulation symbol stream is given a transformation corresponding to the first modulation symbol stream only in a first direction among two mutually perpendicular first and second directions in the complex plane representing the first modulation symbol stream and the second modulation symbol stream.

[0615] Thereby, the receiving device can derive the second data sequence without waiting for the derivation of the first data sequence or the like. Therefore, the receiving device can suppress the processing delay. That is, the receiving device can perform efficient processing on a multiplexing method using superposition coding.

[0616] In addition, the receiving device can receive a multiplexed signal of the first modulation symbol stream and the second modulation symbol stream adjusted according to the first modulation symbol stream in the first direction on the complex plane. Therefore, the receiving device can appropriately derive the first data sequence and the second data sequence from the multiplexed signal in which the first data sequence and the second data sequence are appropriately multiplexed.

[0617] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first modulation symbol in the first modulation symbol stream and the second modulation symbol in the second modulation symbol stream, where the multiplexed signal is a multiplexed signal in which the polarity of the component of the second modulation symbol in the first direction is inverted when the component of the first modulation symbol in the first direction satisfies a specified condition.

[0618] Thus, the receiving device can receive, as a multiplexed signal, a signal obtained by superimposing a first modulation symbol and a second modulation symbol whose polarity in the first direction on the complex plane is inverted according to the first modulation symbol. By inverting the polarity of the second modulation symbol, multiple signal points corresponding to the same bit group of the second data sequence are close to each other. Therefore, the receiving device can appropriately generate a second likelihood stream corresponding to the second modulation symbol stream from the multiplexed signal including the first modulation symbol stream.

[0619] Alternatively, for example, the second demapping unit may generate the second likelihood stream by demapping the multiplexed signal based on a superimposed constellation, where the superimposed constellation is a constellation obtained by combining a first constellation used in the mapping of the first bit stream and a second constellation used in the mapping of the second bit stream, and reflects the inversion of the polarity.

[0620] Thus, the receiving device can appropriately generate a second likelihood stream corresponding to the second modulation symbol stream from the multiplexed signal based on the superimposed constellation in which multiple signal points corresponding to the same bit group are close to each other.

[0621] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first modulation symbol stream generated by mapping the first bit stream using a first constellation in which multiple signal points are dispersed only in the first direction among the first direction and the second direction and the second modulation symbol stream generated by mapping the second bit stream using a second constellation in which multiple signal points are dispersed in both the first direction and the second direction and given the transformation.

[0622] Thus, the receiving device can receive a multiplexed signal to which superimposed coding is applied to the first direction. That is, the receiving device can receive a multiplexed signal in which the component of the first modulation symbol in the first modulation symbol stream in the first direction and the component of the second modulation symbol in the second modulation symbol stream in the first direction are superimposed on one component.

[0623] In addition, the receiving device can receive a multiplexed signal to which superimposed coding is appropriately applied to the first direction using the second modulation symbol stream adjusted for the first direction. Therefore, the receiving device can appropriately generate a second likelihood stream corresponding to the second modulation symbol stream from the multiplexed signal.

[0624] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first modulated symbol stream and the second modulated symbol stream that is generated by mapping the second bit stream using the second constellation whose noise tolerance in the first direction is higher than that in the second direction and to which the transformation is applied.

[0625] Thereby, for the first direction, the influence of the reduced noise tolerance due to the superimposed coding is suppressed.

[0626] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first modulated symbol stream and the second modulated symbol stream that is generated by mapping the second bit stream using the second constellation whose number of values in the first direction is smaller than that in the second direction and to which the transformation is applied.

[0627] Thereby, for the first direction, the influence of the increased number of values due to the superimposed coding is suppressed.

[0628] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first component that the first modulated symbol in the first modulated symbol stream and the second modulated symbol in the second modulated symbol stream have for the first direction and the second component that the second modulated symbol has for the second direction, and the first component is superimposed at a ratio larger than that of the second component.

[0629] Thereby, the first component in the first direction becomes relatively smaller, and the second component in the second direction perpendicular to the first direction becomes relatively larger. Thus, the receiving device can receive the multiplexed signal in which the superimposed coding is appropriately applied to the first component and the influence of the superimposed coding is suppressed for the second component.

[0630] Alternatively, for example, the receiving unit may receive the multiplexed signal obtained by superimposing the first modulated symbol in the first modulated symbol stream and the second modulated symbol in the second modulated symbol stream. When the first modulated symbol corresponds to one of two adjacent signal points in the first constellation, the polarity of the component that the second modulated symbol has for the first direction is inverted, and when the first modulated symbol corresponds to the other of the two signal points, the polarity is maintained.

[0631] Thereby, the receiving device can appropriately generate the second bit likelihood stream corresponding to the second modulated symbol stream from the multiplexed signal whose polarity is appropriately controlled.

[0632] Alternatively, for example, the receiving device may further include: an encoding unit that generates a first bit stream of the first data sequence by performing error control encoding on the first data sequence derived by the first decoding unit; a mapping unit that generates the first modulated symbol stream by mapping the first bit stream; a delay unit that delays the multiplexed signal received by the receiving unit by a predetermined time; and a subtraction unit that subtracts the first modulated symbol stream from the multiplexed signal delayed by the delay unit. The second demapping unit generates the second likelihood stream by demapping the multiplexed signal when the signal-to-noise ratio of the multiplexed signal satisfies a predetermined criterion and the multiplexed signal includes the first modulated symbol stream as an undetermined signal component. The second demapping unit generates the second likelihood stream by demapping the multiplexed signal from which the first modulated symbol stream has been subtracted when the signal-to-noise ratio of the multiplexed signal does not satisfy the predetermined criterion.

[0633] Thereby, the receiving device can switch between the operation of demapping the multiplexed signal without removing the first modulated symbol stream and the operation of demapping the multiplexed signal from which the first modulated symbol stream has been removed according to the signal-to-noise ratio. Therefore, the receiving device can suppress an extreme reduction in transmission capacity and the like.

[0634] In addition, a receiving method according to one aspect of the present disclosure receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superposition coding, and derives the plurality of data sequences from the multiplexed signal. In the receiving method, the multiplexed signal is received, and a first likelihood stream of the first data sequence is generated by demapping the multiplexed signal when the multiplexed signal includes a second modulated symbol stream of the second data sequence as an undetermined signal component. A second likelihood stream of the second data sequence is generated by demapping the multiplexed signal when the multiplexed signal includes a first modulated symbol stream of the first data sequence as an undetermined signal component. The first data sequence is derived by performing error control decoding on the first likelihood stream, and the second data sequence is derived by performing error control decoding on the second likelihood stream. In the reception of the multiplexed signal, the multiplexed signal in which the first modulated symbol stream generated by mapping the first bit stream of the first data sequence and the second modulated symbol stream generated by mapping the second bit stream of the second data sequence are superimposed at a predetermined amplitude ratio is received. The second modulated symbol stream is subjected to a transformation corresponding to the first modulated symbol stream only in a first direction among mutually perpendicular first and second directions in the complex plane representing the first modulated symbol stream and the second modulated symbol stream.

[0635] Accordingly, a receiving device or the like using this receiving method can derive a second data sequence without waiting for the derivation of the first data sequence or the like. Therefore, a receiving device or the like using this receiving method can suppress processing delay. That is, a receiving device or the like using this receiving method can perform efficient processing on a multiplexing method using superimposed coding.

[0636] In addition, a receiving device or the like using this receiving method can receive a multiplexed signal of a first modulated symbol stream and a second modulated symbol stream adjusted according to the first modulated symbol stream in a first direction on the complex plane. Therefore, a receiving device or the like using this receiving method can appropriately derive the first data sequence and the second data sequence from the multiplexed signal in which the first data sequence and the second data sequence are appropriately multiplexed.

[0637] In addition, for example, in the reception of the multiplexed signal, the multiplexed signal in which a first modulated symbol in the first modulated symbol stream and a second modulated symbol in the second modulated symbol stream are superimposed may be received, and the polarity of the component of the second modulated symbol in the first direction is inverted when the component of the first modulated symbol in the first direction satisfies a specified condition.

[0638] Accordingly, a receiving device or the like using this receiving method can receive, as a multiplexed signal, a signal in which a first modulated symbol and a second modulated symbol whose polarity is inverted according to the first modulated symbol in a first direction on the complex plane are superimposed. By inverting the polarity of the second modulated symbol, a plurality of signal points corresponding to the same bit group of the second data sequence approach. Therefore, a receiving device or the like using this receiving method can appropriately generate a second likelihood stream corresponding to the second modulated symbol stream from the multiplexed signal including the first modulated symbol stream.

[0639] In addition, for example, in the generation of the second likelihood stream, the second likelihood stream may be generated by demapping the multiplexed signal based on a superimposed constellation, which is a constellation obtained by combining a first constellation used in the mapping of the first symbol stream and a second constellation used in the mapping of the second symbol stream, and which reflects the inversion of the polarity.

[0640] Accordingly, a receiving device or the like using this receiving method can appropriately generate a second likelihood stream corresponding to the second modulated symbol stream from the multiplexed signal based on the superimposed constellation in which a plurality of signal points corresponding to the same bit group approach.

[0641] Alternatively, for example, in the reception of the multiplexed signal, the multiplexed signal is received in which the first modulated symbol stream generated by mapping the first bit stream by using a first constellation in which a plurality of signal points are dispersed only in the first direction out of the first direction and the second direction is superimposed on the second modulated symbol stream generated by mapping the second bit stream by using a second constellation in which a plurality of signal points are dispersed in both the first direction and the second direction and which is given the transformation.

[0642] Accordingly, a receiving apparatus or the like using this reception method can receive a multiplexed signal to which superposition coding is applied in the first direction. That is, a receiving apparatus or the like using this reception method can receive a multiplexed signal in which the component of the first modulated symbol in the first modulated symbol stream in the first direction and the component of the second modulated symbol in the second modulated symbol stream in the first direction are superimposed on one component.

[0643] In addition, a receiving apparatus or the like using this reception method can receive a multiplexed signal in which superposition coding is appropriately applied in the first direction by using the second modulated symbol stream adjusted for the first direction in the first direction. Therefore, a receiving apparatus or the like using this reception method can appropriately generate a second likelihood stream corresponding to the second modulated symbol stream from the multiplexed signal.

[0644] Alternatively, for example, in the reception of the multiplexed signal, the multiplexed signal is received in which the first modulated symbol stream is superimposed on the second modulated symbol stream generated by mapping the second bit stream by using the second constellation in which the noise tolerance in the first direction is higher than the noise tolerance in the second direction and which is given the transformation.

[0645] Accordingly, for the first direction, the influence of the noise tolerance reduction due to the superposition coding is suppressed.

[0646] Alternatively, for example, in the reception of the multiplexed signal, the multiplexed signal is received in which the first modulated symbol stream is superimposed on the second modulated symbol stream generated by mapping the second bit stream by using the second constellation in which the number of values in the first direction is smaller than the number of values in the second direction and which is given the transformation.

[0647] Accordingly, for the first direction, the influence of the increase in the number of values due to the superposition coding is suppressed.

[0648] Alternatively, for example, in the reception of the multiplexed signal, the multiplexed signal may be such that the first modulation symbol in the first modulation symbol stream, the first component of the second modulation symbol in the second modulation symbol stream in the first direction, and the second component of the second modulation symbol in the second direction are superimposed, and the first component is superimposed at a larger ratio than the second component.

[0649] As a result, the first component in the first direction becomes relatively smaller, and the second component in the second direction perpendicular to the first direction becomes relatively larger. Therefore, a receiving device or the like using this receiving method can receive a multiplexed signal in which superposition coding is appropriately applied to the first component and the influence of superposition coding is suppressed for the second component.

[0650] Alternatively, for example, in the reception of the multiplexed signal, the multiplexed signal may be such that the first modulation symbol in the first modulation symbol stream and the second modulation symbol in the second modulation symbol stream are superimposed. When the first modulation symbol corresponds to one of two adjacent signal points in the first constellation, the polarity of the component of the second modulation symbol in the first direction is inverted, and when the first modulation symbol corresponds to the other of the two signal points, the polarity is maintained.

[0651] As a result, a receiving device or the like using this receiving method can appropriately generate a second likelihood stream corresponding to the second modulation symbol stream from the multiplexed signal with appropriately controlled polarity.

[0652] Alternatively, for example, the receiving method may further include: generating a first bit stream of the first data sequence by performing error control coding on the derived first data sequence, generating the first modulation symbol stream by mapping the first bit stream, delaying the received multiplexed signal by a predetermined time, subtracting the first modulation symbol stream from the delayed multiplexed signal, and in the generation of the second likelihood stream, when the signal-to-noise ratio of the multiplexed signal satisfies a predetermined criterion, generating the second likelihood stream by demapping the multiplexed signal in a state where the multiplexed signal includes the first modulation symbol stream as an undetermined signal component, and when the signal-to-noise ratio of the multiplexed signal does not satisfy the predetermined criterion, generating the second likelihood stream by demapping the multiplexed signal from which the first modulation symbol stream has been subtracted.

[0653] Accordingly, a receiving device or the like using this receiving method can switch the operation of demapping a multiplexed signal without removing the first modulated symbol stream and the operation of demapping a multiplexed signal from which the first modulated symbol stream has been removed according to the signal-to-noise ratio. Therefore, a receiving device or the like using this receiving method can suppress an extreme reduction in transmission capacity and the like.

[0654] In addition, in the description of each of the above embodiments, for the sake of simplicity of description, the case where two data sequences are multiplexed and transmitted in two layers has been described as an example. However, it is obvious that it can be easily extended according to the embodiment even in the case where three or more data sequences are multiplexed and transmitted.

[0655] In addition, Figure 1 、 13 Examples in FIGS. 10 to 15 and 24 to 26 show cases where a transmitting device does not have an antenna and transmits a radio band signal from an external antenna connected to the transmitting device. However, it may also be that the transmitting device has an antenna and transmits a radio band signal from the antenna of the transmitting device.

[0656] In addition, in Figure 2 、 7 Examples in FIGS. 16 to 19 and 27 to 30 show cases where a receiving device does not have an antenna and receives a radio band signal from an external antenna connected to the receiving device. However, it may also be that the receiving device has an antenna and receives a radio band signal using the antenna of the receiving device.

[0657] In addition, the antenna used for transmitting or receiving a radio band signal may also be an antenna unit composed of a plurality of antennas.

[0658] In addition, although not illustrated in Figure 1 、 13 ~15、24~26, the transmitting device may also include a frame forming unit that configures the superimposed signal generated by the adding unit according to a predetermined frame structure to generate a frame and outputs the frame to the RF unit.

[0659] Here, the structure of the frame generated by the frame forming unit may be fixed or may be changed according to a control signal transmitted from a control unit (not illustrated). The frame forming unit configures the superimposed modulation symbol stream obtained by multiplexing the first data sequence and the second data sequence into the frame according to a predetermined rule.

[0660] In addition, the frame generated by the frame forming unit includes, in addition to data symbols, pilot symbols, control information symbols, preambles, and the like. In addition, the pilot symbols, control information symbols, and preambles may sometimes be called by different names.

[0661] For example, a pilot symbol can be a symbol generated by performing a mapping process of PSK modulation such as BPSK and QPSK on a bit stream known to the receiving device. Additionally, a pilot symbol can be a symbol having an amplitude and a phase (or a known complex value) known to the receiving device. Additionally, a pilot symbol can be a symbol capable of estimating the amplitude and phase (or complex value) transmitted by the transmitting device by the receiving device.

[0662] Moreover, the receiving device uses pilot symbols to perform frequency synchronization, time synchronization, channel estimation, etc. on the received signal. Channel estimation is also referred to as the estimation of CSI (Channel State Information).

[0663] A control information symbol is a symbol used in the transmission of information that should be notified to the receiving device as information for demodulating the received signal to obtain a desired data sequence.

[0664] For example, the transmitting device transmits a control information symbol corresponding to the control information. The control information can also represent the mapping (modulation) method used for each data sequence, the error control coding method, the coding rate and code length of the error control coding method, and the position of the modulated symbols of the data sequence in the frame, etc. The receiving device demodulates the control information symbol to obtain the control information. Then, the receiving device demodulates the data symbol based on the obtained control information to obtain the data sequence.

[0665] Additionally, the control information can also include setting information in the upper layer for controlling the actions of the application, etc.

[0666] A preamble is a signal added at the beginning of a frame. The receiving device can also receive a signal including a preamble and perform processing such as frame detection and frame synchronization based on the preamble. Additionally, the preamble can also include pilot symbols and control information symbols. Additionally, a frame can include not only a preamble but also a signal added at the end of the frame, i.e., a postamble.

[0667] The encoding unit uses, for example, LDPC (Low Density Parity Check) codes or Turbo codes, etc. as the error control coding method. Additionally, the encoding unit can also use other coding methods.

[0668] Figure 1 、 13 ~15, 24~26, the transmitting device is equipped with an interleaving unit, but the transmitting device may not be equipped with an interleaving unit as described above. In this case, the transmitting device can either directly input the bit stream generated by the encoding unit into the mapping unit or input it into the mapping unit after performing a process different from interleaving. Additionally, when the transmitting device does not have an interleaving unit,Figure 2 , 7 The receiving apparatuses for 16 - 19 and 27 - 30 may not have a deinterleaving section either.

[0669] In addition, Figure 2 , 7 The deinterleaving section of the receiving apparatuses for 16 - 19 and 27 - 30 performs sorting based on a sorting rule opposite to the sorting rule performed on the transmission side, but it may also perform an operation different from such sorting. For example, the deinterleaving section may input multiple bit likelihoods of the bit likelihood stream generated by the demapping section to the decoding section in the bit order required in the decoding process performed by the decoding section.

[0670] In addition, in the above, superposition coding and transform superposition coding are applied to wireless transmission, but are not limited to wireless transmission, and may also be applied to wired transmission, optical transmission, etc., and may also be applied to recording on a recording medium. In addition, the frequency band used for transmission is not limited to the wireless frequency band and may also be the baseband.

[0671] In addition, "a plurality of" used in this disclosure has the same meaning as "two or more". In addition, ordinal numbers such as first, second, and third may be appropriately removed in expression, may be replaced, or may be newly added.

[0672] In addition, the apparatuses, methods, etc. in this disclosure are not limited to the respective embodiments and can be implemented with various modifications. For example, in the respective embodiments, the technology of this disclosure is implemented as a communication apparatus (transmission apparatus or receiving apparatus), but the technology of this disclosure is not limited thereto. The technology of this disclosure may also be implemented as software for executing the communication method (transmission method or receiving method) performed by the communication apparatus.

[0673] In addition, two or more structural elements in the transmission apparatus or the receiving apparatus may be combined into one structural element, or one structural element may be divided into two or more structural elements. In addition, the transmission apparatus and the receiving apparatus may form a transceiver apparatus. In this case, multiple structural elements of the same type may also be combined into one structural element. For example, the transmission antenna and the receiving antenna may also be formed by one antenna.

[0674] In addition, for example, the processing performed by a specific structural element may be performed by other structural elements. In addition, the order of performing the processing may be changed, or multiple processes may be performed in parallel.

[0675] In addition, for example, a program for executing the above communication method may be pre - stored in a ROM (Read Only Memory), and the CPU (Central Processor Unit) may execute the program.

[0676] In addition, a program for executing the above communication method can also be stored in a computer-readable storage medium. Then, the program stored in the storage medium can also be recorded in the RAM (Random Access Memory) of a computer, and the computer executes the communication method according to the program.

[0677] Then, each structural element in the above-described multiple embodiments and the like can also be implemented as a typical integrated circuit, i.e., LSI (Large Scale Integration). Each structural element can be monolithicized individually, or all or a part of the structural elements of each embodiment can be monolithicized. Here, LSI is exemplified, and such an integrated circuit is sometimes also called an IC (Integrated Circuit), a system LSI, a super LSI, or an ultra LSI depending on the difference in integration degree.

[0678] The method of integrating into an integrated circuit is not limited to LSI. Each structural element can also be implemented using a dedicated circuit or a general-purpose processor. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI, or a reconfigurable processor that can reconstruct the connection or setting of circuit units inside the LSI can also be used.

[0679] Moreover, if a technology for replacing the integration of LSI with an integrated circuit by the progress of semiconductor technology or other derived technologies appears, it is of course possible to use such a technology to integrate the devices or a part of their structures described in each embodiment. For example, the adaptation of biotechnology may occur.

[0680] The present disclosure can also be widely applied to a wireless system that transmits different modulation signals (multiplexed signals) from multiple antennas. In addition, the present disclosure can also be applied to MIMO (Multiple Input Multiple Output) transmission in a wired communication system having multiple transmission sites. As an example of such a wired communication system, there are a PLC (Power Line Communication) system, an optical communication system, and a DSL (Digital Subscriber Line) system.

[0681] Industrial Applicability

[0682] The present disclosure can be applied to a wireless communication system, a broadcast system, and the like. In addition, the present disclosure can be widely applied to a system that multiplexes multiple data sequences using superposition coding.

[0683] In addition, the present disclosure can also be applied to wired communication systems such as, for example, PLC (Power Line Communication) systems, optical communication systems, and DSL (Digital Subscriber Line) systems. In addition, the present disclosure can also be applied to storage systems that record on recording media such as optical discs and magnetic discs, etc.

[0684] Explanation of Reference Numerals

[0685] 100, 500, 600, 700, 1200, 1300, 1400: Transmitting device

[0686] 111, 121, 214, 414, 511, 521, 611, 621, 711, 721, 814, 914, 1014, 1211, 1221, 1311, 1321, 1411, 1421, 1514, 1614, 1714: Encoding unit

[0687] 112, 122, 215, 415, 512, 522, 612, 622, 712, 722, 815, 915, 1015, 1212, 1222, 1312, 1322, 1412, 1422, 1515, 1615, 1715: Interleaving unit

[0688] 113, 123, 216, 416, 513, 523, 613, 623, 713, 723, 816, 916, 1016, 1213, 1223, 1313, 1323, 1413, 1423, 1516, 1616, 1716: Mapping unit

[0689] 114, 124, 217, 417, 514, 524, 614, 624, 714, 724, 817, 917, 1017, 1214, 1224, 1314, 1324, 1414, 1424, 1517, 1617, 1717: Multiplication unit

[0690] 130, 530, 630, 730, 1230, 1330, 1430: Addition unit

[0691] 140, 230, 330, 430, 540, 640, 740, 830, 930, 1030, 1130, 1240, 1340, 1440, 1530, 1630, 1730, 1830: RF unit (Radio Frequency unit)

[0692] 200, 300, 400, 800, 900, 1000, 1100, 1500, 1600, 1700, 1800: Receiving device

[0693] 211, 221, 310, 411, 421, 811, 821, 911, 921, 1011, 1021, 1110, 1511, 1521, 1611, 1621, 1711, 1721, 1810: Demapping unit

[0694] 212, 222, 312, 322, 412, 422, 812, 822, 912, 922, 1012, 1022, 1112, 1122, 1512, 1522, 1612, 1622, 1712, 1722, 1812, 1822: Deinterleaving unit

[0695] 213, 223, 313, 323, 413, 423, 813, 823, 913, 923, 1013, 1023, 1113, 1123, 1513, 1523, 1613, 1623, 1713, 1723, 1813, 1823: Decoding unit

[0696] 218, 418, 818, 918, 1018, 1518, 1618, 1718: Delay unit

[0697] 219, 419, 819, 919, 1019, 1519, 1619, 1719: Subtraction unit

[0698] 525, 625, 820, 920, 1225, 1325, 1520, 1620: Transformation unit

Claims

1. A receiving device that receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superposition coding, and derives the plurality of data sequences from the multiplexed signal. The receiving device includes: a receiving unit that receives the multiplexed signal; a first demapping unit that generates a first likelihood stream of the first data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a second modulation symbol stream of the second data sequence as an undetermined signal component; a second demapping unit that generates a second likelihood stream of the second data sequence by demapping the multiplexed signal in a state where the multiplexed signal includes a first modulation symbol stream of the first data sequence as an undetermined signal component; a first decoding unit that derives the first data sequence by performing error control decoding on the first likelihood stream; and a second decoding unit that derives the second data sequence by performing error control decoding on the second likelihood stream, wherein the receiving unit receives the multiplexed signal in which the first modulation symbol stream generated by mapping a first bit stream of the first data sequence and the second modulation symbol stream generated by mapping a second bit stream of the second data sequence are superimposed at a prescribed amplitude ratio, and the second modulation symbol stream is given a transformation corresponding to the first modulation symbol stream only in a first direction among mutually perpendicular first and second directions in a complex plane representing the first modulation symbol stream and the second modulation symbol stream.

2. The receiving device according to claim 1, wherein the first modulation symbol stream is modulated by using BPSK, i.e., binary phase shift keying.

3. A receiving method that receives a multiplexed signal in which a plurality of data sequences including a first data sequence of a first layer and a second data sequence of a second layer are multiplexed by superposition coding, and derives the plurality of data sequences from the multiplexed signal. In the receiving method, the multiplexed signal is received, a first likelihood stream of the first data sequence is generated by demapping the multiplexed signal in a state where the multiplexed signal includes a second modulation symbol stream of the second data sequence as an undetermined signal component, a second likelihood stream of the second data sequence is generated by demapping the multiplexed signal in a state where the multiplexed signal includes a first modulation symbol stream of the first data sequence as an undetermined signal component, the first data sequence is derived by performing error control decoding on the first likelihood stream, the second data sequence is derived by performing error control decoding on the second likelihood stream, In the reception of the multiplexed signal, the multiplexed signal is received, which is formed by superimposing, at a prescribed amplitude ratio, the first modulated symbol stream generated by mapping the first bit stream of the first data sequence and the second modulated symbol stream generated by mapping the second bit stream of the second data sequence. The second modulated symbol stream is given a transformation corresponding to the first modulated symbol stream only in a first direction among mutually perpendicular first and second directions in the complex plane representing the first modulated symbol stream and the second modulated symbol stream.

4. The receiving method according to claim 3, wherein, the first modulated symbol stream is modulated by using BPSK, i.e., binary phase shift keying.

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