Relay device and relay method

Abstract

To provide a relay device and a method for relay which relay a multiple signal.SOLUTION: The relay device according to an embodiment includes: a reception unit for receiving a multiple signal including a first modulation signal of a first power level and a second modulation signal of a second power level different from the first power level; a demodulation unit for demodulating the multiple signal; a decoding unit for decoding the output of the demodulation unit; a coding unit for coding the output of the decoding unit; a modulation unit for modulating the output of the coding unit; a cancellation unit for cancelling the output of the modulation unit from the output of the demodulation unit; and a transmission unit for transmitting an output signal of the cancellation unit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a radio signal relay device and relay method. [Background technology]

[0002] The relay device receives the signal transmitted from the transmitting device, processes the received signal, and transmits the processed signal to the receiving device.

[0003] In recent years, in order to improve frequency utilization efficiency, a Layered Division Multiplexing (LDM) system has been proposed in which two different signals are transmitted simultaneously in the same band by transmitting a layered multiplexed signal in which two different signals are added together at different power levels. In this specification, a layered multiplexed signal may also be simply referred to as a multiplexed signal.

[0004] Conventional repeaters do not take the LDM system into consideration, and therefore are unable to correctly demodulate multiplexed signals and are therefore unable to relay multiplexed signals. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-67123 [Patent Document 2] Patent Publication No. 2021-72614 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a relay device and a relay method for relaying a multiplexed signal. [Means for solving the problem]

[0007] A relay device according to an embodiment includes a receiver that receives a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level, a demodulator that demodulates the multiplexed signal, a decoder that decodes an output of the demodulator, a coder that encodes the output of the decoder, a modulator that modulates the output of the coder, a canceller that cancels the output of the modulator from the output of the demodulator, and a transmitter that transmits an output signal of the canceller. 1st A transmitter; an amplifier for amplifying the multiplexed signal; and a second transmitter for transmitting an output signal of the amplifier; It is equipped with: [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a conceptual diagram illustrating an example of a system according to a first embodiment. [Figure 2] FIG. 2 is a block diagram illustrating an example of a repeater according to the first embodiment. [Figure 3] FIG. 2 is a block diagram illustrating an example of an output unit of the repeater according to the first embodiment. [Figure 4] FIG. 2 is a diagram showing an example of a time waveform of a signal modulated by the ASK method according to the first embodiment. [Figure 5] FIG. 4 is a diagram showing another example of the time waveform of a signal modulated by the ASK method according to the first embodiment. [Figure 6] FIG. 2 is a block diagram for explaining an example of hierarchical multiplexing in an LDM system according to the first embodiment. [Figure 7] FIG. 2 is a diagram for explaining an example of a hierarchical multiplexed signal according to the first embodiment. [Figure 8] FIG. 3 is a diagram for explaining an example of a first signal and a second signal according to the first embodiment. [Figure 9] 4A and 4B are diagrams for explaining an example of a received signal after amplitude adjustment in a demodulation unit of the repeater according to the first embodiment. [Figure 10] 4A and 4B are diagrams showing examples of signals processed by each unit of a transmitter, a repeater, and a receiver in the first embodiment and a comparative example. [Figure 11] FIG. 10 is a block diagram illustrating an example of a repeater according to a second embodiment. [Figure 12]FIG. 10 is a block diagram illustrating an example of a repeater according to a third embodiment. [Figure 13] FIG. 2 is a diagram for explaining an example of one OFDM segment transmitted by a transmitter according to the first embodiment. [Figure 14] FIG. 10 is a block diagram showing an example of a repeater according to a fourth embodiment. [Figure 15] FIG. 13 is a block diagram showing an example of a repeater according to a fifth embodiment. [Figure 16] FIG. 11 is a diagram showing a constellation map in a repeater according to the fifth embodiment. [Figure 17] FIG. 13 is a diagram for explaining an example of the operation of a likelihood operating unit 134 according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments with reference to the drawings. The following description exemplifies devices and methods embodying the technical concepts of the embodiments. The technical concepts of the embodiments are not limited to the structures, shapes, arrangements, materials, etc. of the components described below. Modifications that can be easily conceived by those skilled in the art are naturally included within the scope of the disclosure. For clarity of explanation, the drawings may schematically depict elements with different sizes, thicknesses, planar dimensions, shapes, etc., compared to the actual embodiment. Elements with different dimensional relationships or ratios may be included in multiple drawings. Corresponding elements may be designated by the same reference numerals in multiple drawings, and redundant description may be omitted. Some elements may be designated by multiple names, but these names are merely examples and do not necessarily mean that these elements may be designated by other names. Furthermore, elements that do not have multiple names may also be designated by other names. In the following description, "connection" may include not only direct connection but also connection via other elements.

[0010] Hereinafter, the present embodiment will be described in detail with reference to the drawings.

[0011] [First embodiment] FIG. 1 is a conceptual diagram illustrating an example of a system according to a first embodiment. The system includes a transmitter 12, a repeater 14, and a receiver 16. The transmitter 12 transmits an encoded transmission signal. The repeater 14 receives the transmission signal transmitted by the transmitter 12, processes the received signal, generates a transmission signal, and transmits the transmission signal. The transmission signal is at least a part of a hierarchical multiplexed signal. The receiver 16 receives the signal transmitted by the repeater 14.

[0012] The signal transmitted by the transmitter 12 is a radio signal. This radio signal is a hierarchical multiplexed signal consisting of a first signal and a second signal having a different power level from the first signal. For example, the power level of the first signal is greater than the power level of the second signal.

[0013] Multiple repeaters 14 may be placed between the transmitter 12 and the receiver 16. A signal transmitted by one repeater 14 may be received by another repeater 14.

[0014] 2 is a block diagram illustrating a repeater 14a, which is an example of the repeater 14 according to the first embodiment. The repeater 14a includes a receiving antenna 22, a demodulation unit 24, a decoding unit 26, an encoding / modulation unit 28, a cancellation unit 30, and an output unit 32. The encoding / demodulation unit 28 may be separated into an encoding unit and a demodulation unit.

[0015] The demodulation unit 24 demodulates the radio signal input from the receiving antenna 22. The demodulation unit 24 includes multiple units, such as a filter unit that removes out-of-band radio signals, an amplifier unit that amplifies the level of the radio signal, a down-conversion unit that converts the radio signal into an analog signal of a baseband frequency, an A / D conversion unit that converts the analog signal of the baseband frequency into a digital signal, and a timing synchronization processing unit that adjusts sample timing or symbol timing. The processing of the multiple units may be performed in the order described, or may be performed in an order different from the order described.

[0016] The demodulation unit 24 demodulates the hierarchical multiplexed signal and outputs the demodulated signal (for example, the output signal of the timing synchronization processing unit) to the decoding unit 26. The demodulation unit 24 outputs the demodulated signal (for example, the output signal of the timing synchronization processing unit) to the cancellation unit 30. The demodulation unit 24 may also output a signal in the middle of demodulation processing (for example, the output signal of the A / D conversion unit) to the cancellation unit 30.

[0017] The decoding unit 26 receives the signal output from the demodulation unit 24, decodes the input signal using a decoding method corresponding to the encoding of the first signal, and outputs the decoded signal to the encoding / modulation unit 28.

[0018] The coding and modulation unit 28 encodes the input signal using the coding method of the first signal, modulates the encoded signal using the modulation method of the first signal, and outputs the modulated encoded signal to the cancellation unit 30. Since the power level of the first signal is sufficiently greater than the power level of the second signal, when demodulating and decoding the first signal, no matter what the content of the second signal is, the second signal can be demodulated and decoded while being largely ignored like noise, and therefore the output of the coding and modulation unit 28 is the first signal.

[0019] The cancellation unit 30 cancels the signal corresponding to the first signal input from the encoding / modulation unit 28 from the hierarchical multiplexed signal input from the demodulation unit 24. To extract the signal corresponding to the second signal from the hierarchical multiplexed signal through this cancellation, the level of the first signal input from the encoding / modulation unit 28 to the cancellation unit 30 may be adjusted (×β, as described later in FIG. 6 ) or the timing between the input signals may be adjusted using a buffer included in the cancellation unit 30. The output of the second signal from the demodulation unit 24 to the cancellation unit can be performed within one clock period. However, the first signal is decoded by the decoding unit 26 and coded and modulated by the encoding / modulation unit 28. This process requires several clock periods. Since the second signal input from the demodulation unit 24 to the cancellation unit must wait for that amount of time, its timing is adjusted. Note that the timing synchronization process of the demodulation unit 24 refers to sample timing synchronization, which oversamples the received signal and finds the optimal sample timing from the oversampled signal. In other embodiments, this may refer to symbol timing synchronization for finding symbol timing from a signal with GI, or frame timing synchronization for finding the beginning of a frame. The cancellation unit 30 supplies a signal corresponding to the second signal obtained by cancellation to the output unit 32.

[0020] The output unit 32 transmits, as a radio signal or an optical signal, a signal corresponding to the second signal output by the cancellation unit 30. The signal transmitted by the repeater 14a is a radio signal or an optical signal.

[0021] FIG. 3 is a block diagram illustrating an example of the output unit 32 of the repeater 14a according to the first embodiment.

[0022] The output unit 32a shown in FIG. 3(a) includes a modulation unit 40 and a transmission antenna 42. The modulation unit 40 includes multiple units, such as a D / A conversion unit, an up-conversion unit that converts an analog baseband signal to an RF frequency, a filter unit that removes out-of-band signals, and an amplifier unit that amplifies the level of the radio signal. The transmission antenna 42 emits a radio signal. The frequency of the radio signal transmitted by the repeater 14a may be the same as or different from the frequency of the radio signal transmitted by the transmitter 12.

[0023] The output unit 32b shown in FIG. 3(b) includes a decoding unit 46 and an optical signal output unit 48. The decoding unit 46 decodes the signal output by the cancellation unit 30 using a decoding method corresponding to the encoding of the second signal. The optical signal output unit 48 converts the signal output by the decoding unit 46 into an optical signal and outputs it. When the repeater 14a demodulates, decodes, and then repeats the received signal in this way, there is no need for demodulation and decoding in the receiver 16. When the repeater 14a includes the output unit 32b, the repeater 14a and another repeater 14a, or the repeater 14a and the receiver 16, are connected by optical fiber. When signals are transmitted via optical fiber, there is almost no degradation in signal transmission quality.

[0024] (Operation of repeater 14a) The specific operation of the repeater 14a will be described below, assuming that the modulation method used by the transmitter 12 is amplitude shift keying.

[0025] FIG. 4 shows an example of the time waveform of a signal modulated by the ASK method according to the first embodiment. FIG. 4(a) shows an example of the time waveform of a signal with an amplitude value of 1. FIG. 4(b) shows an example of the time waveform of a signal with an amplitude value of 0. The symbol length is assumed to be ts. FIG. 4(a) represents the waveform of a binary 1 (0b1), and FIG. 4(b) represents the waveform of a binary 0 (0b0). FIG. 4 shows an example where the amplitude values ​​are two values, 0 and 1, and the number of bits transmitted per symbol is 1. The modulation method for the first signal and the second signal may be the same method (both ASK methods), or may be different modulation methods.

[0026] Fig. 5 shows another example of the time waveform of a signal modulated by the ASK method according to the first embodiment. Fig. 5 shows an example in which the amplitude values ​​are four values: 0, 0.33, 0.67, and 1, and the number of bits transmitted per symbol is 2. Fig. 5(a) shows the waveform of binary 11 (0b11), Fig. 5(b) shows the waveform of binary 10 (0b10), Fig. 5(c) shows the waveform of binary 00 (0b00), and Fig. 5(d) shows the waveform of binary 01 (0b01). The encoding method shown in Fig. 5 is also called Gray code.

[0027] 6 is a block diagram illustrating an example of hierarchical multiplexing in the LDM system according to the first embodiment. Hierarchical multiplexing is performed by a first signal generation unit 52, a first power adjustment unit 54, a second signal generation unit 62, a second power adjustment unit 64, and an adder 56. The first signal generation unit 52 generates a first signal and outputs the first signal to the first power adjustment unit 54. The first power adjustment unit 54 adjusts the power level of the input first signal and outputs the adjusted first signal to the adder 56. The second signal generation unit 62 generates a second signal and outputs the second signal to the second power adjustment unit 64. The second power adjustment unit 64 adjusts the power level of the input second signal and outputs the adjusted second signal to the adder 56. The adder 56 adds the two input signals and outputs a hierarchical multiplexing signal indicating the addition result. The first power adjustment unit 54 multiplies the input signal by β. The second power adjustment unit 64 multiplies the input signal by αβ. α is called a scaling coefficient, and β is called a normalization coefficient. Here, α<1, but this is not limiting.

[0028] 7 is a diagram illustrating an example of a hierarchical multiplexed signal according to the first embodiment. Since the second signal is multiplied by the scaling coefficient α, the signal level of the second signal is lower than the signal level of the first signal. Therefore, the first signal is also referred to as an upper layer signal, and the second signal is also referred to as a lower layer signal. The power level ratio of the two layer signals (the ratio of the power level of the first signal to the power level of the second signal) is referred to as an injection level. Examples of the injection level are 23 dB or 15 dB.

[0029] One application of LDM hierarchical multiplexing is being considered for the next-generation standard for the current terrestrial digital television broadcasting, known as Integrated Services Digital Broadcasting-Terrestrial (ISDB-T). By using LDM, the next-generation standard and the current standard can coexist.

[0030] As an example, a hierarchical multiplexed signal is transmitted in which a signal conforming to the ISDB-T standard (hereinafter referred to as the ISDB-T signal) is used as the first signal, and a signal conforming to a next-generation terrestrial digital television broadcasting standard (e.g., the 4K8K standard or the Super Hi-Vision (SHV) standard) that is an advanced version of the ISDB-T standard (hereinafter referred to as the SHV signal) is used as the second signal. This makes it possible to transmit the SHV signal without allocating a new frequency to the SHV signal.

[0031] Note that multiplexing is not limited to two-layer signals, but may involve three or more layer signals. Multiplexing is not limited to multiple different signals, but may involve multiple identical signals multiplexed at different power levels. For example, the layer-multiplexed signal may not include ISDB-T signals, and SHV signals may be multiplexed in upper and lower layers.

[0032] The encoding of the transmitter 12 will now be described. One example of an encoding method is the repetition method. When 0b1 is repeated three times and encoded, the encoded signal becomes 0b111, and when 0b0 is repeated three times and encoded, the encoded signal becomes 0b000. When 0b11 is repeated three times and encoded, the encoded signal becomes 0b111111. When 0b10 is repeated three times and encoded, the encoded signal becomes 0b111000. When 0b00 is repeated three times and encoded, the encoded signal becomes 0b000000. When 0b01 is repeated three times and encoded, the encoded signal becomes 0b000111.

[0033] When decoding an encoded signal in the repeater 14a or the receiver 16, decoding may be performed by majority decision. For example, when the encoded signal 0b001 is received, the encoded signal 0b001 is decoded as 0b0 because the number of 0b0 bits is greater than the number of 0b1 bits.

[0034] FIG. 8 is a diagram illustrating an example of a first signal and a second signal according to the first embodiment. FIG. 8(a) shows an example of a time waveform generated by the first signal generating unit 52. The first signal is encoded using a three-time repetition scheme. FIG. 8(a) shows a case where the signal generating unit 52 modulates a signal in which the first signal before encoding is 0b101... and the first signal after encoding is 0b111000111... using ASK. FIG. 8(b) is a diagram illustrating an example of a time waveform generated by the second signal generating unit 62. The second signal is encoded using a five-time repetition scheme. FIG. 8(b) shows a case where the second signal before encoding is 0b10... and the second signal after encoding is 0b1111100000... and the second signal after encoding is modulated using ASK. FIG. 8(c) is a diagram illustrating an example of a time waveform of a signal in which the first signal and the second signal are hierarchically multiplexed. The hierarchical multiplexing in Figure 8(c) is hierarchical multiplexing when the scaling coefficient α = 0.1 (amplitude is 0.1 times) and the normalization coefficient β = 1. Since the amplitude value of the first signal after power adjustment is 0.0 or 1.0 and the amplitude value of the second signal after power adjustment is 0.0 or 0.1, the amplitude value of the ASK modulated signal (Figure 8(c)) after hierarchical multiplexing is 0.0, 0.1, 1.0, or 1.1. Transmitter 12 transmits the hierarchically multiplexed signal shown in Figure 8(c).

[0035] FIG. 9 is a diagram for explaining an example of the amplitude-adjusted received signal in the demodulation unit 24 of the repeater 14a according to the first embodiment. FIG. 9 shows a signal amplitude-adjusted by the amplifier unit of the demodulation unit 24. The amplitude adjustment is to adjust the power level of the received signal. The wireless signal includes a pilot signal described later. The pilot signal is a known signal. The amplifier unit adjusts the power level of the received signal so that the power level of the pilot signal included in the received signal matches the power level of the known signal. Alternatively, assuming that 0b0 and 0b1 are generated with equal probability at the transmitter 12, the adjustment may be made so that the average value of the values of a plurality of received symbols becomes 0.55.

[0036] The signal transmitted by the transmitter 12 may not be correctly received by the repeater 14a due to attenuation due to propagation loss, the influence of multipath in the transmission path, or the influence of additive white Gaussian noise (AWGN) generated in the repeater 14a. The amplitudes of the transmission signals shown in FIG. 8(c) are 1.1, 1.1, 1.1, 0.1, 0.1, 0.0, 1.0,... in order from the first symbol. The amplitudes of the signals after amplitude adjustment in the demodulation unit 24 of the repeater 14 shown in FIG. 9 are 1.1, 1.1, 1.1, 0.6, 0.1, 0.0, 1.0,... in order from the first symbol. The amplitude 0.6 of the fourth symbol (at 3ts < t < 4ts) of the signal in FIG. 9 has changed with respect to the amplitude 0.1 of the fourth symbol of the transmission signal (FIG. 8(c)).

[0037] The decoding unit 26 determines (hard decision) the amplitude of the signal after the timing synchronization processing in the demodulation unit 24 to be a value close to either 0 or 1. Since the amplitudes of the signals after the timing synchronization processing are 1.1, 1.1, 1.1, 0.6, 0.1, 0.0, 1.0,... in order from the first symbol as shown in FIG. 9, the hard decision results are 1, 1, 1, 1, 0, 0, 1,... in order from the first symbol. The decoding unit 26 further decodes this decision result by majority decision every three symbols. The decoding result is 0b10....

[0038] The coding and modulation unit 28 encodes the output of the decoding unit 26 using the repetition system. The encoded signal is 0b111000.... The hard decision result 1, 1, 1, 0, 0, 1,... and the encoded signal 1, 1, 1, 0, 0, 0, 1,... differ in the bit of the fourth symbol. Bit 1 of the fourth symbol of the hard decision result is changed to bit 0 in the encoded signal. The coding and modulation unit 28 modulates this encoded signal using the ASK system. The modulation result is a radio signal with an amplitude of 1.0, 1.0, 1.0, 0.0, 0.0, 0.0,.... The modulation result is a signal corresponding to the first signal.

[0039] The cancellation unit 30 cancels the modulation result from the encoding / modulation unit 28 from the signal (FIG. 9) after amplification by the demodulation unit 24, and obtains an ASK-modulated signal with amplitudes of 0.1, 0.1, 0.1, 0.6, 0.1, 0.0, .... This signal corresponds to the second signal.

[0040] The output unit 32 transmits this modulated signal as a radio signal or an optical signal.

[0041] The amplitudes of the signal transmitted by the output unit 32 are 0.1, 0.1, 0.1, 0.6, 0.1, 0.0, .... Since the amplitudes of the second signal are 0.0 and 0.1, the receiver 16 decodes the signal using 0.05, which is in between, as a reference. The decoding results of the receiver 16 are 1, 1, 1, 1, 1, 0, 0, .... Therefore, the receiver 16 can generate the second signal based on the signal transmitted from the repeater 14a according to the first embodiment. In this way, the repeater 14a can correct (compensate) for changes in the amplitude of the modulated signal contained in the received signal (deterioration of signal quality) by decoding, encoding, and demodulating the received signal. Note that the output unit 32 may amplify the amplitude input from the cancellation unit before transmitting. For example, the amplitude may be amplified by 10 times, and an amplitude of 0.1 may be transmitted as an amplitude of 1.0, and an amplitude of 0.0 may be transmitted as an amplitude of 0.0.

[0042] (Comparative Example) As a comparative example, a repeater that does not perform decoding processing and performs only modulation processing instead of encoding and modulation is assumed. In the repeater of the comparative example, the decoding unit 26 of the repeater 14a is omitted, and a modulation unit is provided instead of the encoding and modulation unit 28. Furthermore, the demodulation unit 28 includes a hard decision processing unit that performs hard decision processing. In the comparative example, the demodulation result is modulated, and this modulation result is canceled from the demodulation result of the demodulation unit 24.

[0043] The signals after hard decision of the amplitude-adjusted signals (FIG. 9) after amplification processing by demodulation unit 24 in the comparative example are 1, 1, 1, 1, 0, 0, 1, ... starting from the first symbol. The modulation unit modulates the hard decision results using the ASK method. The modulation result is a signal with amplitudes of 1.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, ...

[0044] The cancellation unit 30 cancels the signal resulting from modulation by the modulation unit from the signal amplified by the demodulation unit 24 (FIG. 9), obtaining an ASK-modulated signal with an amplitude of 0.1, 0.1, 0.1, 0.0, 0.1, 0.0, ... The fourth symbol of this ASK-modulated signal is 0.6-1.0=-0.4, but since there are no negative amplitudes, it is set to 0.0. Since the amplitudes of the signal output from the cancellation unit 30 are 0.0 and 0.1, if the intermediate value of 0.05 is used as the decoding standard, the ASK-modulated signal with an amplitude of 0.1, 0.1, 0.1, 0.0, 0.1, 0.0, ... is likely to be decoded as 1, 1, 1, 0, 1, 0, ... by the receiver 16. Since the signal transmitted by the repeater already contains errors, the reception performance of the receiver 16 deteriorates.

[0045] FIG. 10 shows an example of signals processed by each section of the transmitter, repeater, and receiver in the first embodiment and the comparative example.

[0046] In the repeater 14a according to the first embodiment, the cancellation unit 30 cancels the signal corresponding to the first signal from the hierarchical multiplexed signal, thereby enabling accurate generation of a signal corresponding to the second signal. The decoding unit 26 decodes and then generates only the signal corresponding to the first signal. The repeater 14a according to the first embodiment can shorten the time required for relaying compared to when both the signal corresponding to the first signal and the signal corresponding to the second signal are decoded and then generated. If the decoding unit 26 and the encoding / modulation unit 28 were omitted from the repeater 14a, the relaying time would be further shortened, but the accuracy of the signal corresponding to the second signal output by the cancellation unit 30 would be lower.

[0047] The repeater 14a according to the first embodiment can relay lower layer signals in a layer multiplexed signal with high quality.

[0048] [Second embodiment] 11 is a block diagram showing an example of a repeater 14b according to the second embodiment. The repeater 14b differs from the repeater 14a in that an amplifier unit 102 and an output unit 32a are added.

[0049] The hierarchical multiplexed signal received by the receiving antenna 22 is output to the demodulator 24 and the amplifier 102. The amplifier 102 amplifies the power level of the hierarchical multiplexed signal and outputs it to the output unit 32a. The output unit 32a transmits the amplified hierarchical multiplexed signal as a radio signal.

[0050] By relaying the hierarchical multiplexed signal via the amplifier unit 102, the repeater 14b can perform low-delay relaying without delays that occur in the demodulator 24, decoder 26, encoder / modulator 28, canceller 30, etc. Furthermore, because the relaying is low-delay, the receiver 16 can receive the hierarchical multiplexed signal with low delay.

[0051] Since the amplifier unit 102 amplifies the power level, the receiver 16 can receive the hierarchical multiplex signal at a relatively large power level. The receiver 16 can obtain the first signal from the hierarchical multiplex signal. Since the power level of the first signal is considerably larger than that of the second signal, there is almost no degradation in signal quality compared to the second signal.

[0052] Since the repeater 14b transmits the signal corresponding to the second signal from the output unit 32 in the same manner as the repeater 14a, the receiver 16 can obtain the second signal with no degradation in signal quality.

[0053] The receiver 16 can receive almost simultaneously the hierarchical multiplex signal (direct signal) transmitted by the transmitter 12 without passing through the repeater 14b and the hierarchical multiplex signal (relayed signal) transmitted by the transmitter 12 via the repeater 14b. Almost simultaneously means that when the time difference between the two signals is Δt, Δt < ts (symbol length). The receiver 16 can receive the same information (hierarchical multiplex signal) from both the transmitter 12 and the repeater 14b at the same timing. That is, an improvement in the reception performance of the receiver 16 can be expected.

[0054] However, depending on the position of the receiver 16, there may be a case where only the transmission signal from the repeater 14b can be received, and due to attenuation of radio wave propagation and white noise (AWGN), the first signal can be correctly demodulated but the second signal cannot be correctly demodulated. In such a case, if the output unit 32 of the repeater 14b transmits the output signal of the canceling unit 30 at a frequency different from that of the first signal, the receiver 16 can receive the second signal. Alternatively, if the output unit 32 of the repeater 14b transmits the output signal of the canceling unit 30 to the receiver 16 via an optical fiber, the receiver 16 can receive the second signal. Note that when the frequencies of the transmission signal of the repeater 14b received by the receiver and the transmission signal of the transmitter 12 are different, there is no interference even if their time difference exceeds the symbol length.

[0055] The repeater 14b according to the second embodiment can relay the lower layer signal with high quality and can relay the above-mentioned hierarchical signal with low latency.

[0056] [Third embodiment] 12 is a block diagram showing an example of a repeater 14c according to the third embodiment. The repeater 14c differs from the repeater 14a in that a determination unit 106 and a selection unit 108 are added.

[0057] The cancellation unit 30 outputs a signal corresponding to the second signal (lower layer signal) to the decision unit 106 and the selection unit 108. The decision unit 106 includes a hard decision unit 112 and a soft decision unit 114. The decision unit 106 determines whether the amplitude of the signal corresponding to the second signal is 0 or 1 by hard decision or soft decision. The selection unit 108 selects either the hard decision unit 112 or the soft decision unit 114. The decision unit 106 outputs the decision result to the output unit 32.

[0058] When the amplitude of the signal corresponding to the first signal changes, the amplitude of the signal corresponding to the second signal deviates significantly from the correct amplitude. Rather than relaying the signal corresponding to the second signal with a significantly deviated amplitude, relaying the signal corresponding to the second signal after determining it using soft decision or hard decision can be expected to improve the reception performance of receiver 16 that receives the relayed signal.

[0059] If the output unit 32 and the receiver 16 are connected by optical fiber, the determination unit 106 can be omitted. Since the receiver 16 is equipped with a determination unit, if there is no degradation in communication quality due to transmission over optical fiber, the same determination result can be expected whether the determination is made by the determination unit of the repeater or the determination unit of the receiver.

[0060] The transmitter 12 error-corrects the first signal and may or may not error-corrects the second signal.

[0061] If the second signal is not error-correction coded, determining the amplitude by the decision unit 106 using hard decision results in better reception performance at the receiver 16 than determining the amplitude using soft decision. The signal received by the receiver 16 is affected by both noise and distortion occurring between the transmitter 12 and the repeater 14c and noise and distortion occurring between the repeater 14c and the receiver 16. Hard decision can reduce the effects of these noises and distortions. However, soft decision can also reduce these noises. The degree of reduction is simply greater with hard decision than with soft decision.

[0062] On the other hand, if the second signal is error-correction coded, determining the amplitude by the decision unit 106 using soft decision may result in better reception performance at the receiver 16 than determining the amplitude using hard decision. If the repeater 14c determines the amplitude using soft decision, an error may occur, but the receiver 16 can correct the error in the decoding process. If the repeater 14c determines the amplitude using hard decision, there is a possibility that the repeater 14c may determine a value different from the true value (the value transmitted by the transmitter 12) (misjudgment). Misjudgment occurs when the decision boundary is exceeded. In the case of the ASK modulation method, the transmitter and receiver agree in advance that an amplitude of 0 is set to 0b0 and an amplitude of 1 is set to 0b1. On the receiver side, due to the influence of AWGN and the like, the amplitude value may take values ​​other than amplitude 0 and amplitude 1, such as 0.1, 0.45, 0.55, and 1.1. It is determined whether each amplitude value is 0b0 or 0b1. In normal decision making, the boundary is 0.5, which is halfway between 0 and 1, and if it is less than 0.5 it is judged as 0b0, otherwise it is judged as 0b1. Without processing such as decoding, the receiving side cannot tell whether the judged 0b0 or 0b1 is correct or an incorrect judgment. If a signal that was judged as 0b0 (amplitude 0) on the transmitting side is received on the receiving side and exceeds the boundary of 0.5, it is judged as 0b1, resulting in an incorrect judgment. Soft decision making reduces the adverse effects of incorrect judgment when the decision boundary is exceeded. By reducing the effects of incorrect judgment using soft decision making, it is possible to obtain a correct signal by performing error correction decoding in the receiver 16.

[0063] The selection unit 108 determines whether the second signal has been error correction coded based on the output signal of the cancellation unit 30. The selection unit 108 selects either the hard decision unit 112 or the soft decision unit 114 depending on the determination result. The selection unit 108 may perform necessary processing to obtain information on a flag indicating whether the second signal has been error correction coded. As another example, the flag indicating whether the second signal has been error correction coded may be obtained from the first signal, or may be obtained by other means.

[0064] The transmitter 12 can transmit a flag in the multiplexed signal that indicates whether the second signal has been error-correction coded.

[0065] The transmitter 12 uses Orthogonal Frequency Division Multiplexing (OFDM) modulation as an example of a signal modulation method. Fig. 13 is a diagram for explaining an example of one OFDM segment transmitted by the transmitter 12 according to the third embodiment. In the example of Fig. 13, one OFDM segment includes 432 carriers. The number of carriers in an OFDM segment is not limited to this example, and the OFDM segment may include 108 or 216 carriers. The 432 carriers are collectively referred to as a symbol group. 13 consecutive OFDM segments in the frequency direction are referred to as one OFDM symbol. In other words, one OFDM symbol contains 5616 (= 13 × 432) carriers. 204 consecutive OFDM symbols in the time direction are referred to as an OFDM frame.

[0066] The transmitter 12 inserts a pilot signal into the OFDM segment (a part of the 432 carrier is used as the pilot signal). The pilot signal is a known signal. By inserting the pilot signal into the OFDM segment, the receiving device can estimate the frequency characteristics of the propagation path by comparing the received pilot signal with a known signal. The receiving device can compensate for degradation of the frequency characteristics of the propagation path by correcting the frequency characteristics of the propagation path according to the estimation result. Degradation of the frequency characteristics of the propagation path may result in errors in the transmitted data. Compensating for degradation of the frequency characteristics of the propagation path can reduce transmission errors.

[0067] Pilot signals include scattered pilot signals (also called SP signals) that are inserted in a dispersed manner in the frequency direction (carrier direction), and continual pilot signals (also called continuous pilot signals, or CP signals) that are inserted continuously in the time direction at frequencies within the transmission band other than the OFDM segment. Note that SP signals may also be inserted in a dispersed manner in the time direction (symbol direction).

[0068] When CP signals are used, one OFDM symbol consists of 5617 carriers. Si,j (i = 0 to 383, j = 0 to 203) represents carriers excluding SP signals and the like.

[0069] When SP signals are used, the transmitter 12 inserts one SP signal for every 12 carriers into the OFDM segment. The insertion period of the SP signals in the frequency direction is the first period (12 carriers). The transmitter 12 inserts one SP signal for every four carriers in the time (symbol number) direction. The insertion period of the SP signals in the time direction is the second period (4 carriers).

[0070] The carrier numbers of the carriers into which the SP signals are inserted may be the same for every few symbol groups. For example, for the symbol group with symbol number 4, the SP signals are inserted into the carriers with carrier numbers 0, 12, ..., just like in the symbol group with symbol number 0.

[0071] The transmitter 12 also inserts a Transmission and Multiplexing Configuration Control (TMCC) signal and an Auxiliary Channel (AC) signal into the OFDM segment.

[0072] TMCC signals are signals used to transmit control information. Control signals are information that assists the demodulation and decoding operations of the receiving device, such as the hierarchical structure and transmission parameters of OFDM segments. Control information includes system identification, a transmission parameter switching indicator, a start control signal (start flag for emergency alert broadcasting), current information, next information, etc. Current information indicates the current transmission parameters of each hierarchical signal, and next information indicates the transmission parameters of each hierarchical signal after switching. Next information can be set or changed at any time before the switching countdown, but cannot be changed during the countdown.

[0073] The transmission parameter information of each layer signal included in the current / next information indicates the carrier modulation mapping method. For example, transmission parameter information "001" indicates the QPSK method, transmission parameter information "010" indicates the 16QAM method, transmission parameter information "011" indicates the 64QAM method, and transmission parameter information "111" indicates that the corresponding layer is unused or that no next information exists. The transmitting device may transmit the transmission parameter information to the relay device by including it in a signal other than the TMCC signal, such as an AC signal, or by including it in any control information other than the pilot signal for channel estimation.

[0074] The AC signal is an extension signal for transmitting additional information related to broadcasting. The additional information is additional information related to transmission control of modulated waves or earthquake warning information. The transmitter 12 includes an encoding flag in the AC signal, which indicates whether the second signal is error-correction encoded. The transmitting device may include the encoding flag in a signal other than the AC signal, such as a TMCC signal, and transmit the signal, or may include the encoding flag in any control information other than a pilot signal for channel estimation and transmit the signal.

[0075] The carriers of the TMCC signal and AC signal are randomly arranged in the frequency direction to reduce the effects of periodic distortion in the propagation path characteristics due to multipath.

[0076] The selection unit 108 demodulates the OFDM frame output from the cancellation unit 30, decodes the demodulated signal, and detects the coding flag. The selection unit 108 selects the hard decision unit 112 or the soft decision unit 114 based on the detected coding flag.

[0077] The selection unit 108 may include a memory that stores selection information for selecting the hard decision unit 112 or the soft decision unit 114 according to any criterion, rather than based on information included in the output signal of the cancellation unit 30, and may determine the selection of the hard decision unit 112 or the soft decision unit 114 based on the selection information. The repeater 14c may include an input unit for writing the selection information to the memory, and a user of the repeater 14c may rewrite the selection information.

[0078] In the repeater 14c according to the third embodiment, the determination unit 106 makes a hard or soft decision on the signal corresponding to the lower layer signal obtained by the cancellation unit 30 depending on whether the lower layer signal is error correction coded or not, and the output unit 32 transmits a signal indicating the decision result, so that the lower layer signal can be relayed with high quality.

[0079] [Fourth embodiment] 14 is a block diagram showing an example of a repeater 14d according to the fourth embodiment. The repeater 14d differs from the repeater 14c in that a multiplexing section 122 is added.

[0080] The determination unit 106 outputs the determination result of the signal corresponding to the second signal (lower layer signal) to the multiplexing unit 122. The encoding and modulation unit 28 outputs a signal corresponding to the modulated first signal to the cancellation unit 30 and also to the multiplexing unit 122. The multiplexing unit 122 multiplexes the signal corresponding to the input first signal with the signal corresponding to the determined second signal. The multiplexing unit 122 outputs a multiplexed signal of the signal corresponding to the first signal and the signal corresponding to the second signal to the output unit 32. The output unit 32 transmits the multiplexed signal wirelessly or as an optical signal.

[0081] The multiplexing unit 122 may include a buffer for storing the signal corresponding to the first signal and a buffer for storing the signal corresponding to the second signal in order to match the timing of the signal corresponding to the first signal and the signal corresponding to the second signal. The demodulation unit 24 adds the same indicator to the signal to be output to the cancellation unit 30 and the signal to be output to the decoding unit 26. The multiplexing unit 122 adjusts the timing of multiplexing the two signals based on the indicator added to the signal corresponding to the input first signal and the indicator added to the signal corresponding to the input second signal.

[0082] The multiplexing unit 122 may have a level adjustment function to adjust the levels of the signal corresponding to the first signal and the signal corresponding to the second signal. For example, if the decision unit 106 normalizes the output after decision and the coding and modulation unit 28 normalizes the output after modulation, the input from the decision unit 106 may be power-adjusted by a circuit similar to the first power adjustment unit 54 in Fig. 6, and the input from the coding and modulation unit 28 may be power-adjusted by a circuit similar to the second power adjustment unit 64 in Fig. 6, and then multiplexed.

[0083] The values ​​of the scaling coefficient α and normalization coefficient β used by the multiplexer 122 for power adjustment may be different from the values ​​of the scaling coefficient α used by the second power adjustment unit 64 of the transmitter 12 and the normalization coefficient β used by the first power adjustment unit 54. For example, if the geographical range of the receiver 16 receiving signals via the repeater 14d is limited and the signal-to-noise ratio (SNR) of the signal passing through the repeater 14d is expected to be relatively high, the receiver 16 is expected to be able to receive the first signal with high quality. In this case, the scaling coefficient α of the repeater 14d may be set larger (the injection level may be smaller) than the scaling coefficient α of the transmitter 12. This increases the possibility of receiving the second signal while maintaining the communication quality of the first signal at a certain level or higher.

[0084] The repeater 14d according to the fourth embodiment includes the multiplexing unit 122, and therefore can relay a high-quality hierarchical multiplexed signal generated from a received hierarchical multiplexed signal.

[0085] [Fifth embodiment] 15 is a block diagram showing an example of a repeater 14e according to the fifth embodiment. The repeater 14e differs from the repeater 14d in that the functional blocks included in the determination unit 106 are explicitly shown, the selection unit 108 is included in the determination unit 106b, and a signal is additionally transmitted from the demodulation unit 24a to the signal quality measurement unit 146 included in the determination unit 106b.

[0086] The demodulation unit 24a demodulates the radio signal input from the receiving antenna 22. The demodulation unit 24a may be the same as the demodulation unit 24, but here it is assumed to be different from the demodulation unit 24. The demodulation unit 24a includes multiple units, such as a filter unit that removes out-of-band radio signals, an amplifier unit that amplifies the level of the radio signal, a quadrature demodulation unit that converts the radio signal into I-channel and Q-channel signals of baseband frequency, an A / D conversion unit that converts analog signals of baseband frequency into digital signals, a timing synchronization processing unit that adjusts symbol timing, an FFT unit that converts time-domain signals into frequency-domain signals, and an equalization unit that corrects distortion in the transmission path.

[0087] The decision unit 106 b includes a likelihood calculation unit 132 , a likelihood manipulation unit 134 , a bit probability calculation unit 136 , a symbol probability calculation unit 138 , a soft replica generation unit 140 , a noise power calculation unit 144 , and a signal quality measurement unit 146 .

[0088] The demodulator 24a demodulates the hierarchically multiplexed signal and outputs the demodulated signal (for example, the output signal of the equalizer) to the decoder 26 and the canceller 30.

[0089] As explained with reference to Fig. 13, a pilot signal is inserted into an OFDM segment. The equalizer of the demodulator 24a extracts the pilot signal from the OFDM segment, compares the extracted pilot signal with a known signal to estimate the frequency characteristics of the propagation path, processes the received signal according to the estimated frequency characteristics, and corrects distortion of the transmission path. The equalizer supplies the estimated frequency characteristics to the signal quality measurement unit 146.

[0090] The cancellation unit 30 outputs a signal corresponding to a second signal (lower layer signal) obtained by canceling the output of the encoding / modulation unit 28 from the output of the demodulation unit 24a to the likelihood calculation unit 132 and the noise power calculation unit 144.

[0091] The noise power calculation unit 144 calculates the noise power included in the signal corresponding to the second signal, and outputs the calculated noise power to the likelihood calculation unit 132 and the signal quality measurement unit 146 .

[0092] The likelihood calculation unit 132 receives the signal corresponding to the second signal from the cancellation unit 30, receives the noise power from the noise power calculation unit 144, and calculates a log-likelihood ratio (LLR) for each bit. The likelihood calculation unit 132 outputs the calculated LLR to the likelihood operation unit 134.

[0093] The signal quality measurement unit 146 measures the signal quality of the second signal from the noise power input from the noise power calculation unit 144 and the information on the frequency characteristics input from the demodulation unit 24a. The signal quality measurement unit 146 outputs the measured signal quality to the likelihood operation unit 134.

[0094] The likelihood manipulation unit 134 receives the LLR from the likelihood calculation unit 132 and the signal quality from the signal quality measurement unit 146. The likelihood manipulation unit 134 selects one likelihood manipulation function from among a plurality of likelihood manipulation functions stored in advance, based on the signal quality. The likelihood manipulation unit 134 changes the LLR using the selected likelihood manipulation function, and outputs the new LLR for each bit after the change.

[0095] The bit probability calculation unit 136 receives the LLR from the likelihood operation unit 134, calculates the bit probability for each bit, and outputs the bit probability.

[0096] The symbol probability calculation unit 138 receives the bit probabilities from the bit probability calculation unit 136, calculates the probabilities of signal points preset on the constellation map, and calculates the symbol probability by aggregating the probabilities for each signal point. The symbol probability calculation unit 138 outputs the calculated symbol probabilities to the soft replica generation unit 140.

[0097] The soft replica generation unit 140 receives the symbol probabilities as input, generates a soft replica that is a signal corresponding to the second signal, and outputs the soft replica to the multiplexing unit 122 .

[0098] The multiplexing unit 122 receives as input the soft replica and a signal corresponding to the modulated first signal from the encoding and modulation unit 28. The multiplexing unit 122 multiplexes the signal corresponding to the input first signal and the soft replica (signal corresponding to the second signal), and outputs the multiplexed signal.

[0099] When the signal quality measured by the signal quality measurement unit 146 is worse than a certain reference quality, the likelihood manipulation unit 134 selects a likelihood manipulation function that causes the decision unit 106b to perform soft decision processing or processing similar thereto.

[0100] On the other hand, if the signal quality is better than the reference quality, the likelihood manipulation unit 134 selects a likelihood manipulation function that causes the decision unit 106b to perform hard decision processing or processing similar to this. In this specification, replicas generated by hard decisions are also called soft replicas.

[0101] As a result, when the signal quality is poor, likelihood manipulation unit 134 changes the LLR calculated by likelihood calculation unit 132 to an LLR calculated from a signal that is superimposed as is with the effects of noise and the like almost completely removed. On the other hand, when the signal quality is good, likelihood manipulation unit 134 changes the LLR calculated by likelihood calculation unit 132 to an LLR calculated from a signal from which the effects of noise and the like have been almost completely removed.

[0102] A signal corresponding to the second signal generated based on the LLR thus changed and a signal corresponding to the first signal modulated by the encoding and modulation unit 28 are hierarchically multiplexed in the multiplexer 122 and transmitted. The receiver 16 can receive a high-quality hierarchically multiplexed signal.

[0103] (Specific operation of repeater 14e) The operation of repeater 14e will be specifically described assuming that the primary modulation method of the first signal transmitted by transmitter 12 is QPSK (Quadrature Phase Shift Keying), the primary modulation method of the second signal is 16QAM (Quadrature Amplitude Modulation), and the secondary modulation method of the first and second signals is OFDM (Orthogonal Frequency Division Multiplexing).

[0104] Fig. 16(a) is a constellation map showing the arrangement of signal points when the first signal is modulated using the QPSK method. Fig. 16(b) is a constellation map showing the arrangement of signal points when the second signal is modulated using 16QAM. Fig. 16(c) is a constellation map showing the arrangement of signal points of a signal obtained by hierarchically multiplexing the first signal and the second signal. The hierarchical multiplexing method may be the same as in Fig. 6.

[0105] The transmitter 12 serial-to-parallel converts the hierarchically multiplexed signal, performs IFFT processing, adds a guard interval (GI), generates a signal secondarily modulated by OFDM, and transmits it.

[0106] The noise power calculation unit 144 calculates the noise power included in the signal corresponding to the input second signal. If the second signal is modulated using 16QAM, it calculates the square of the distance between the signal point of the input symbol and the signal point on the constellation map that is closest to the input symbol signal point. This squared value is the noise power. The noise power calculation unit 144 may also calculate the average value of multiple noise powers calculated from multiple input symbol signal points as the noise power.

[0107] The likelihood calculation unit 132 calculates the LLR for each bit using the signal corresponding to the second signal and noise power. Assume that one symbol transmits multiple bits of data. The likelihood calculation unit 132 calculates the LLR of the k-th bit of one symbol using Equation 1.

number

[0108] The signal quality measurement unit 146 receives noise power and frequency characteristic information. The frequency characteristic information is a value (complex number) that represents the frequency characteristic of the transmission path of each subcarrier estimated by pilot subcarriers, etc. The larger the absolute value of the value that represents the frequency characteristic of the transmission path of each subcarrier, the higher the reliability of that subcarrier. The frequency characteristic (complex number) of the transmission path of the n-th subcarrier is expressed as f n Then, the signal quality measurement unit 146 measures the signal quality Q as shown in Equation 2.

[0109] Q=(|fn | 2 ) / σ2 Equation 2 The signal quality measurement unit 146 outputs the measured signal quality to the likelihood operation unit 134 .

[0110] Likelihood manipulation unit 134 receives the LLR from likelihood calculation unit 132 and the signal quality from signal quality measurement unit 146. Likelihood manipulation unit 134 compares the received signal quality with a preset threshold, and if the threshold is higher, selects a likelihood manipulation function g1(x) that causes decision unit 106b to perform soft decision processing or processing similar thereto. Likelihood manipulation unit 134 compares the received signal quality with a preset threshold, and if the signal quality is higher, selects a likelihood manipulation function g2(x) that causes decision unit 106b to perform hard decision processing or processing similar thereto.

[0111] The likelihood manipulation unit 134 receives the LLR as input x, and outputs the value obtained by the likelihood manipulation function g1(x) or g2(x) as the new LLR after the change.

[0112] Fig. 17 is a diagram illustrating an example of the operation of the likelihood manipulation unit 134 according to the fifth embodiment. Fig. 17(a) is a diagram illustrating an example of the likelihood manipulation function g1(x). The likelihood manipulation function g1(x) is a function that limits the lower limit of the LLR to -a (limiter processing) and limits the upper limit of the LLR to +a. The likelihood manipulation function g1(x) outputs the input x as is (g1(x)=x) when -a≦x≦+a, fixes the output to -a (g1(x)=-a) when x<-a, and fixes the output to +a (g1(x)=a) when x>+a.

[0113] 17(b) is a diagram for explaining an example of likelihood manipulation function g2(x). When -b≦x≦+b, likelihood manipulation function g2(x) outputs a value obtained by multiplying input x by gradient a / b (g2(x)=(a / b)x), when x<-b, it fixes the output to -a (g2(x)=-a), and when x>+b, it fixes the output to +a (g2(x)=a). Here, 0 <b<aである。

[0114] k-th bit probability Pk (0) and P k (1) is P k (0)+P k (1)=1. The bit probability calculation unit 136 calculates the LLR k Using the bit probability P k (0), P k (1) is calculated using Equation 3 and Equation 4.

[0115] P k (0)=exp(LLR k ) / (1+exp(LLR k )) Equation 3 P k (1)=1 / ((1+exp(LLR k )) Equation 4 The symbol probability calculation unit 138 calculates the symbol probability according to the bit sequence represented by the symbol using Equation 5.

number

[0116] The soft replica generator 140 calculates the symbol probability Q(x j ) and calculate the position (I coordinate, Q coordinate) of the soft replica using Equations 6 and 7.

number

[0117] Since the likelihood operation function can be changed according to the signal quality, determination can be made at a determination rate corresponding to the signal quality. As a result, an improvement in the reception performance of the receiver 16 can be expected.

[0118] The repeater 14e according to the fifth embodiment hard-determines or soft-determines the signal corresponding to the lower-layer signal obtained by the cancellation unit 30 according to the signal quality of the lower-layer signal, and hierarchically multiplexes the signal indicating the determination result and the signal corresponding to the upper-layer signal, thereby enabling high-quality relaying of the hierarchically multiplexed signal.

[0119] The repeater 14d according to the fourth embodiment and the repeater 14e according to the fifth embodiment include a multiplexing unit 122. However, when relaying a signal to another repeater 14, a hierarchically multiplexed signal is transmitted. When the repeater 14d and the repeater 14e relay a signal to the receiver 16, they may transmit a hierarchically multiplexed signal or a signal corresponding to the lower-layer signal.

[0120] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied in practice without departing from the spirit of the invention. Furthermore, various inventions can be created by appropriately combining multiple components disclosed in the above-described embodiments. For example, some components may be omitted from all the components shown in the embodiments. Furthermore, components from different embodiments may be appropriately combined. [Explanation of symbols]

[0121] 12...Transmitter, 14...Repeater, 16...Receiver, 22...Receiving antenna, 24...Demodulation unit, 26...Decoding unit, 28...Encoding and modulation unit, 30...Cancellation unit, 32...Output unit, 40...Modulation unit, 44...Demodulation unit, 46...Decoding unit, 48...Optical signal output unit

Claims

1. a receiving unit that receives a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; a demodulation unit that demodulates the multiplexed signal; a decoding unit that decodes the output of the demodulation unit; a modulation unit that encodes the output of the decoding unit and modulates the encoded signal; a canceller that cancels the output of the modulator from the output of the demodulator; a first transmitting unit that transmits an output signal of the canceling unit; an amplifier that amplifies the multiplexed signal; a second transmitting unit that transmits the output signal of the amplifying unit.

2. A receiver for receiving a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; a demodulation unit that demodulates the multiplexed signal; a decoding unit that decodes the output of the demodulation unit; a modulation unit that encodes the output of the decoding unit and modulates the encoded signal; a canceller that cancels the output of the modulator from the output of the demodulator; a determination unit that determines a value of the output of the cancellation unit; a multiplexing unit that multiplexes a signal indicating the determination result of the determination unit and an output signal of the modulation unit; a first transmitter that transmits a signal indicating a multiplexing result of the multiplexer; Equipped with the multiplexing unit multiplexes the signal indicating the determination result of the determination unit and the output signal of the modulation unit at different power levels; a power level of the signal indicating the determination result is different from a power level of the second modulated signal; a relay device, wherein the power level of the output signal of the modulation unit is different from the power level of the first modulated signal;

3. A receiver for receiving a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; a demodulation unit that demodulates the multiplexed signal; a decoding unit that decodes the output of the demodulation unit; a modulation unit that encodes the output of the decoding unit and modulates the encoded signal; a canceller that cancels the output of the modulator from the output of the demodulator; a determination unit that determines a value of the output of the cancellation unit by hard decision or soft decision; a first transmitting unit that transmits a signal indicating a determination result of the determining unit; Equipped with The determination unit If the second modulated signal is error correction coded, determining the value by the soft decision; If the second modulated signal is not error-correction coded, the relay device determines the value by hard decision.

4. A relay device as described in claim 1, wherein the output signal of the modulation unit is a signal corresponding to the first modulation signal.

5. An amplifier that amplifies the multiplexed signal; 4. The relay device according to claim 2, further comprising: a second transmitting unit that transmits the output signal of the amplifying unit.

6. further comprising a determination unit that determines a value of the output of the cancellation unit; The relay device according to claim 1 , wherein the first transmission unit transmits a signal indicating a determination result of the determination unit.

7. further comprising a multiplexing unit that multiplexes a signal indicating the determination result of the determination unit and an output signal of the modulation unit; The relay device according to claim 6 , wherein the first transmitting section transmits a signal indicating a multiplexing result of the multiplexing section.

8. The multiplexing unit multiplexes a signal indicating the determination result of the determination unit and an output signal of the modulation unit at different power levels, a power level of the signal indicating the determination result is different from a power level of the second modulated signal; The relay device according to claim 7 , wherein a power level of the output signal of said modulation section and a power level of said first modulated signal are different.

9. A relay device as described in claim 2, wherein the judgment unit judges the value by hard judgment or soft judgment.

10. The determination unit: If the second modulated signal is error correction coded, determining the value by the soft decision; The relay device according to claim 9 , wherein when the second modulated signal is not error-correction coded, the value is determined by the hard decision.

11. A relay device as described in Claim 10, wherein the multiplexed signal includes a flag indicating whether the second modulated signal is error correction coded or not.

12. Further comprising a quality measurement unit for measuring signal quality of at least a part of the multiplexed signal; The determination unit When the signal quality of at least a part of the multiplexed signal is worse than a first quality, the value is determined by the soft decision; The relay device according to claim 9 , wherein when the signal quality of at least the part of the multiplexed signals is better than the first quality, the value is determined by the hard decision.

13. A method for transmitting a modulated signal comprising: receiving a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; demodulating the multiplexed signal; decoding the demodulation result; encoding the decoding result and modulating the encoded signal; canceling the modulation result from the demodulation result; Sending the cancellation result; amplifying the multiplexed signal; and transmitting the amplified result.

14. A method for transmitting a modulated signal comprising: receiving a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; demodulating the multiplexed signal; decoding the demodulation result; encoding the decoding result and modulating the encoded signal; canceling the modulation result from the demodulation result; determining a cancellation result value; multiplexing a signal indicating the determination result and the modulation result; transmitting a signal indicative of the multiplexed result; Equipped with The multiplexing step multiplexes the signal indicating the determination result and the modulation result at different power levels, a power level of the signal indicating the determination result is different from a power level of the second modulated signal; A relay method, wherein the power level of the modulation result is different from the power level of the first modulated signal.

15. A method for transmitting a modulated signal comprising: receiving a multiplexed signal including a first modulated signal at a first power level and a second modulated signal at a second power level different from the first power level; demodulating the multiplexed signal; decoding the demodulation result; encoding the decoding result and modulating the encoded signal; canceling the modulation result from the demodulation result; determining the value of the cancellation result by hard decision or soft decision; transmitting a signal indicative of the determination result; Equipped with The determining step comprises: If the second modulated signal is error correction coded, determining the value by the soft decision; If the second modulated signal is not error-correction coded, the value is determined by hard decision.

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