Transmitting device and receiving device

Abstract

To provide a transmitting device and a receiving device capable of executing appropriate interleaving processing in the time direction even when a modulation multilevel number is adaptively changed.SOLUTION: A transmission device includes a parallel conversion unit that converts a serial bit string constituting an error correction block into two or more parallel bit strings, an interleaving unit that applies cyclic interleaving that cyclically shifts each of the two or more parallel bit strings output from the parallel conversion unit in the time direction in units of symbols according to the modulation multilevel number, and a modulation unit that modulates each of the two or more parallel bit strings output from the interleaving unit in units of symbols according to the modulation multilevel number, and the cycle in which the modulation multilevel number can be changed is determined according to the interval for applying the cyclic interleaving.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a transmitting device and a receiving device. [Background technology]

[0002] There is known a digital wireless transmission system (e.g., FPU; Field Pickup Unit) that wirelessly transmits a digital signal from a transmitting device to a receiving device. In the digital wireless transmission system, a TDD-SVD-MIMO (Time Division Duplex-Singular Value Decomposition-Multiple-Input Multiple-Output) method is being studied. In the TDD-SVD-MIMO method, adaptive control is performed to feed back transmission parameters (e.g., coding rate of error correction code and modulation multi-level number) from the receiving device to the transmitting device, making it possible to perform large-capacity and stable transmission from the transmitting device to the receiving device.

[0003] On the other hand, in general, digital wireless transmission systems perform a process called interleaving, which is a process of changing the order of bits, in order to improve the correction ability of error correction codes. Among digital wireless transmission systems, particularly in systems using OFDM, a method called convolutional interleaving is often used for bits transmitted by each subcarrier. Convolutional interleaving has the advantage of requiring less delay time for interleaving compared to other interleaving methods, and is widely used in FPU systems and digital broadcasting systems. In convolutional interleaving, a different delay time is applied to the OFDM symbols for each subcarrier (for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] "Portable microwave OFDM digital wireless transmission system for ultra-high definition television broadcasting program material transmission" Standard ARIB STD-B75 Version 1.0 Summary of the Invention [Problem to be solved by the invention]

[0005] As a result of intensive research, the inventors have noticed the necessity of adaptively changing the modulation level according to the state of the transmission path between the transmitting device and the receiving device. Furthermore, the inventors have found that adaptively changing the modulation level results in adaptively changing the number of bits represented by one OFDM symbol, making it impossible to appropriately execute the above-mentioned convolutional interleaving process.

[0006] Therefore, the present invention has been made to solve the above-mentioned problems, and aims to provide a transmitting device and a receiving device that are capable of performing appropriate time-direction interleaving processing even when the modulation multi-value number is adaptively changed. [Means for solving the problem]

[0007] A transmitting device according to one embodiment of the disclosure includes a parallel conversion unit that converts a serial bit sequence constituting an error correction block into two or more parallel bit sequences, an interleaving unit that applies cyclic interleaving to each of the two or more parallel bit sequences output from the parallel conversion unit by shifting each of the two or more parallel bit sequences cyclically in the time direction in symbol units corresponding to a modulation multi-level number, and a modulation unit that modulates each of the two or more parallel bit sequences output from the interleaving unit by symbol units corresponding to the modulation multi-level number, and a period for changing the modulation multi-level number is determined according to an interval for applying the cyclic interleaving.

[0008] A receiving device according to one embodiment of the disclosure includes a demodulation unit that outputs two or more parallel bit strings by demodulating two or more parallel symbols corresponding to the number of subcarriers according to a modulation multi-level number, a deinterleaving unit that applies cyclic deinterleaving to each of the two or more parallel bit strings output from the demodulation unit, which cyclically shifts each of the two or more parallel bit strings output from the demodulation unit in the time direction in symbol units corresponding to the modulation multi-level number, and a serial conversion unit that converts the two or more parallel bit strings output from the deinterleaving unit into a serial bit string, and a period for changing the modulation multi-level number is determined according to an interval at which the cyclic deinterleaving is applied. Effect of the Invention

[0009] According to the present invention, it is possible to provide a transmitting device and a receiving device that are capable of performing appropriate interleaving processing in the time direction even when the modulation multi-level number is adaptively changed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a digital wireless transmission system 10 according to an embodiment. [Diagram 2] FIG. 2 is a block diagram showing a transmission device 100 according to the embodiment. [Diagram 3] FIG. 3 is a block diagram showing a receiving device 200 according to the embodiment. [Figure 4] FIG. 4 is a diagram for explaining the problems associated with the conventional technology. [Diagram 5] FIG. 5 is a diagram for explaining the problems associated with the conventional technology. [Figure 6] FIG. 6 is a diagram for explaining cyclic interleaving according to the embodiment. [Figure 7] FIG. 7 is a diagram for explaining cyclic deinterleaving according to the embodiment. [Figure 8] FIG. 8 is a diagram for explaining a variation according to the embodiment. [Figure 9] FIG. 9 is a diagram for explaining a first option according to the embodiment. [Figure 10] FIG. 10 is a diagram for explaining the second option according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and the ratios of dimensions may differ from those of the actual ones.

[0012] Therefore, specific dimensions should be determined with reference to the following description. In addition, the drawings may of course include parts with different dimensional relationships and ratios.

[0013] [Disclosure Summary] A transmitting device according to the outline of the disclosure includes a parallel conversion unit that converts a serial bit sequence that constitutes an error correction block into two or more parallel bit sequences, an interleaving unit that applies cyclic interleaving to each of the two or more parallel bit sequences output from the parallel conversion unit by shifting each of the two or more parallel bit sequences cyclically in the time direction in symbol units corresponding to a modulation multi-level number, and a modulation unit that modulates each of the two or more parallel bit sequences output from the interleaving unit by symbol units corresponding to the modulation multi-level number, and a period for changing the modulation multi-level number is determined according to an interval for applying the cyclic interleaving.

[0014] In the outline of the disclosure, under the premise that the transmitting device applies cyclic interleaving, the period for changing the modulation multi-level number is determined according to the interval for applying cyclic interleaving. With this configuration, by adopting cyclic interleaving instead of convolutional interleaving and limiting the period during which the modulation multi-level number can be changed by the interval, it is possible to adaptively change the modulation multi-level number while executing appropriate interleaving processing in the time direction.

[0015] A receiving device according to the outline of the disclosure includes a demodulation unit that outputs two or more parallel bit strings by demodulating two or more parallel symbols corresponding to the number of subcarriers in accordance with a modulation multi-level number, a deinterleaving unit that applies cyclic deinterleaving to each of the two or more parallel bit strings output from the demodulation unit, which cyclically shifts each of the two or more parallel bit strings output from the demodulation unit in the time direction in symbol units corresponding to the modulation multi-level number, and a serial conversion unit that converts the two or more parallel bit strings output from the deinterleaving unit into a serial bit string, and a period during which the modulation multi-level number can be changed is determined according to an interval at which the cyclic deinterleaving is applied.

[0016] In the outline of the disclosure, under the premise that the receiving device applies cyclic deinterleaving, the period for changing the modulation multi-level number is determined according to the interval for applying cyclic deinterleaving. With this configuration, by adopting cyclic deinterleaving instead of convolutional deinterleaving and limiting the period for changing the modulation multi-level number by the interval, it is possible to adaptively change the modulation multi-level number while executing appropriate deinterleaving processing in the time direction.

[0017] [Embodiment] (Digital Radio Transmission System) A digital wireless transmission system according to an embodiment will be described below. Fig. 1 is a diagram showing a digital wireless transmission system 10 according to an embodiment. As shown in Fig. 1, the digital wireless transmission system includes a transmitting device 100 and a receiving device 200.

[0018] In the embodiment, the digital wireless transmission system is a system that supports wireless transmission of 4K8K broadcast program materials. The transmitting device 100 and the receiving device 200 may be FPUs (Field Pickup Units). In the digital wireless transmission system 10, OFDM (Orthogonal Frequency Division Multiplexing) and interleaving processing that rearranges the order of bits in symbol units according to the modulation multi-value number in the time direction are applied. In the digital wireless transmission system 10, MIMO (Multiple-Input Multiple-Output) may be applied. The method adopted in the digital wireless transmission system 10 may be a TDD-SVD-MIMO (Time Division Duplex-Singular Value Decomposition-Multiple-Input Multiple-Output) method.

[0019] (Transmitting device) A transmitting device according to an embodiment will be described below. Fig. 2 is a block diagram showing the transmitting device 100 according to an embodiment.

[0020] As shown in FIG. 2, the transmission device 100 includes an error correction coding unit 101, an S / P (Serial to Parallel) conversion unit 103, an interleaving unit 105, an OFDM modulation unit 111, and a control unit 113.

[0021] The error correction coding unit 101 generates an error correction block (hereinafter, FEC (Forward Error Correction) block) by applying an error correction code to a transmission bit string (transmission data). Although not particularly limited, the error correction coding unit 101 may use a turbo code or an LDPC (Low-Density Parity-check Code) as the error correction code. For example, the FEC block may include a block header, a main signal (transmission bit string), a BCH code parity, stuff bits, and an LDPC code parity.

[0022] The S / P conversion unit 103 constitutes a parallel conversion unit that converts a serial bit string that constitutes an FEC block into two or more parallel bit strings (hereinafter, k-parallel bit strings). The value of k may be an integer of 2 or more. Although not particularly limited, the value of k may be equal to the number of subcarriers. The S / P conversion unit 103 may perform S / P conversion in units of p bits (p is an integer of 1 or more). p may be the number of bits to be included in a symbol according to the modulation multi-level number.

[0023] The interleaving unit 105 executes an interleaving process that rearranges the order of bits in the time direction in symbol units corresponding to the modulation multi-level number. In the embodiment, cyclic interleaving is used as the interleaving process. The interleaving unit 105 constitutes an interleaving unit that applies cyclic interleaving that cyclically shifts each of two or more parallel bit strings output from the S / P conversion unit 103 in the time direction in symbol units corresponding to the modulation multi-level number.

[0024] Specifically, the interleaving unit 105 stores the kth buffer 107 (buffer 107 1 ~Buffer 107 k ) and the k sorting unit 109 (sorting unit 109 1 ~Sort section 109 k ). Buffer 107 stores bits corresponding to an interval to which cyclic interleaving is applied. The interval may be defined by an integer multiple of a frame (hereinafter, OFDM frame). The OFDM frame may be defined by an integer multiple of an OFDM symbol. Rearrangement unit 109 cyclically shifts the bits stored in buffer 107 in the time direction in symbol units. The amount of cyclic shift applied to rearrangement unit 109 may be different for each rearrangement unit 109.

[0025] For example, when the modulation level is 6 bits and the modulation method is 64QAM, the interleaving unit 105 performs cyclic interleaving with 6 bits as one unit. When the modulation level is 8 bits and the modulation method is 256QAM, the interleaving unit 105 performs cyclic interleaving with 8 bits as one unit.

[0026] The OFDM modulation unit 111 configures an OFDM frame by applying OFDM modulation based on a modulation multi-level number to the parallel bit strings output from the interleaving unit 105. The OFDM frame is a frame configured by a predetermined number of carriers arranged along the frequency direction and a predetermined number of OFDM symbols arranged along the time direction. The OFDM modulation unit 111 may perform addition of a GI (Guard Interval) or may perform orthogonal modulation. The transmitting device 100 transmits the OFDM frame (transmission signal) using each subcarrier.

[0027] In the embodiment, the OFDM modulation unit 111 constitutes a modulation unit that modulates each of two or more parallel bit strings output from the interleaving unit 105 in symbol units according to the modulation multi-level number.

[0028] The control unit 113 controls the interleaving unit 105 and the OFDM modulation unit 111. Specifically, the control unit 113 switches the unit of cyclic shift in the time direction (the number of bits constituting a symbol) based on the modulation multi-level number. The control unit 113 notifies the OFDM modulation unit 111 of the modulation multi-level number, and the OFDM modulation unit 111 performs OFDM modulation based on the notified modulation multi-level number.

[0029] When S / P conversion is performed in units of bits to be included in a symbol according to a modulation level, the control unit 113 may control the S / P conversion unit 103. Specifically, the control unit 113 may switch the unit for applying S / P conversion based on the modulation level.

[0030] Under such a premise, the period during which the modulation level can be changed is determined according to the interval to which cyclic interleaving is applied. In other words, the change of the modulation level is restricted in the middle of the interval. The period during which the modulation level can be changed is changed based on the control information received from the receiving device 200.

[0031] The transmitting device 200 may change the coding rate, the precoding weight, etc., in units of the above-mentioned OFDM frames. On the other hand, the transmitting device 200 changes the modulation multi-level number in units of intervals.

[0032] (Receiving device) The receiving device according to the embodiment will be described below. Fig. 3 is a block diagram showing the receiving device 200 according to the embodiment.

[0033] As shown in FIG. 3, receiving apparatus 200 has OFDM demodulation section 201, deinterleaving section 203, P / S (Parallel to Serial) conversion section 209, error correction decoding section 211, control section 213, and feedback section 215.

[0034] The receiving device 200 receives an OFDM frame (received signal) using each subcarrier from the transmitting device 100. The OFDM demodulation unit 201 demodulates the received signal. The OFDM demodulation unit 201 may perform orthogonal demodulation and may perform GI removal.

[0035] In an embodiment, the OFDM demodulation unit 201 constitutes a demodulation unit that outputs two or more parallel bit strings (hereinafter, k parallel bit strings) by applying OFDM demodulation based on a modulation multi-level number to two or more parallel symbols corresponding to the number of subcarriers.

[0036] The deinterleaving unit 203 executes a deinterleaving process that rearranges the order of bits in the time direction in symbol units corresponding to the modulation multi-level number. In the embodiment, cyclic deinterleaving is used as the deinterleaving process. The deinterleaving unit 203 constitutes a deinterleaving unit that applies cyclic deinterleaving that cyclically shifts each of two or more parallel bit strings output from the OFDM demodulation unit 201 in the time direction in symbol units corresponding to the modulation multi-level number. The process of the deinterleaving unit 203 is the reverse process of the process of the interleaving unit 105 described above.

[0037] Specifically, the deinterleaver 203 includes a buffer 205 (buffer 205 1 ~Buffer 205 k ), and the k sorting unit 207 (sorting unit 207 1 ~Sort section 207 k ) The buffer 205 stores bits corresponding to an interval to which the cyclic deinterleaving is applied. The interval may be defined by an integer multiple of an OFDM frame. The rearrangement unit 207 cyclically shifts the bits stored in the buffer 205 in the time direction in units of symbols. The amount of cyclic shift applied to the rearrangement unit 207 may be different for each rearrangement unit 207.

[0038] For example, when the modulation level is 64QAM, the deinterleaving unit 203 performs cyclic deinterleaving on information bits equivalent to 6-bit received data (6 bits of received data × number of bits representing the LLR of 1 bit of received data) as one unit. When the modulation level is 256QAM, the deinterleaving unit 203 performs cyclic deinterleaving on information bits equivalent to 8-bit received data (8 bits of received data × number of bits representing the LLR of 1 bit of received data) as one unit.

[0039] The P / S conversion unit 209 constitutes a serial conversion unit that converts the parallel k bit strings output from the deinterleaving unit 203 into a serial bit string. The process of the P / S conversion unit 209 is the inverse process of the process of the S / P conversion unit 103 described above.

[0040] The error correction decoding unit 211 decodes the FEC block and acquires received data based on the serial bit string output from the P / S conversion unit 209. The process of the error correction decoding unit 211 is the reverse process of the process of the error correction coding unit 101 described above.

[0041] The control unit 213 controls the OFDM demodulation unit 201 and the deinterleaving unit 203. Specifically, the control unit 213 switches the unit of cyclic shift in the time direction (the number of bits constituting a symbol) based on the modulation multi-level number. The control unit 213 notifies the OFDM demodulation unit 201 of the modulation multi-level number, and the OFDM demodulation unit 201 performs OFDM modulation based on the notified modulation multi-level number.

[0042] When P / S conversion is performed in units of bits to be included in a symbol according to a modulation level, the control unit 213 may control the P / S conversion unit 209. Specifically, the control unit 213 may switch the unit for applying the P / S conversion based on the modulation level.

[0043] The feedback unit 215 transmits control information including an information element for specifying a modulation level. The feedback unit 215 may generate control information for the m-th OFDM frame based on the reception quality of the m-1-th OFDM frame (m is an integer equal to or greater than 1). As the reception quality, MER (Modulation Error Ratio) or the like may be used. The control information may be transmitted via any line.

[0044] Under such a premise, the period during which the modulation level can be changed is determined according to the interval to which the cyclic deinterleaving is applied. In other words, the change of the modulation level is restricted in the middle of the interval. The period during which the modulation level can be changed is changed based on the control information received from the receiving device 200.

[0045] (assignment) Problems associated with the conventional techniques will be described below, specifically problems associated with the convolutional interleaving process and the convolutional deinterleaving process employed in the conventional techniques.

[0046] Here, for the sake of simplicity, the problems associated with the conventional technology will be described using an example in which an OFDM frame is composed of 4 subcarriers×5 OFDM symbols.

[0047] First, a case will be illustrated in which the modulation level of OFDM frame X is 256QAM and the modulation level of OFDM frame X+1 is changed to 64QAM. In such a case, as shown in FIG. 4, when convolutional interleaving is performed, some of the OFDM symbols included in OFDM frame X are shifted to OFDM frame X+1. However, since the number of bits transmitted by the subcarriers of the OFDM symbols included in OFDM frame X is 8 bits, while the number of bits transmitted by the subcarriers of the OFDM symbols in OFDM frame X+1 is 6 bits, it is not possible to shift some of the bits transmitted by the subcarriers of the OFDM symbols included in OFDM frame X to OFDM frame X+1 by convolutional interleaving. That is, it is not possible to adaptively increase the modulation level.

[0048] Secondly, a case will be illustrated where the modulation level of OFDM frame Y is 64QAM and the modulation level of OFDM frame Y+1 is changed to 256QAM. In such a case, as shown in Fig. 5, when convolutional interleaving is performed, some of the OFDM symbols included in OFDM frame Y are shifted to OFDM frame Y+1. However, since the number of bits transmitted by the subcarriers of the OFDM symbols included in OFDM frame Y is 6 bits, while the number of bits transmitted by the subcarriers of the OFDM symbols of OFDM frame Y+1 is 8 bits, it is considered that 2 bits (=8-6 bits) of stuff bits are added when some of the bits transmitted by the subcarriers of the OFDM symbols included in OFDM frame Y are shifted to OFDM frame Y+1 by convolutional interleaving, but information elements (e.g., the original number of bits, etc.) for removing stuff bits need to be managed for each subcarrier of each OFDM symbol. When the number of subcarriers or the delay due to convolutional interleaving increases, the number of information elements for removing stuff bits also increases, so it is not easy to adaptively reduce the number of modulation levels.

[0049] As a result of careful investigation, the inventors have found the above-mentioned problems and have discovered that by adopting cyclic interleaving (cyclic deinterleaving) instead of convolutional interleaving processing (convolutional deinterleaving processing), and determining the period during which the modulation multi-level number can be changed according to the interval at which the cyclic interleaving (cyclic deinterleaving) is applied, it is possible to adaptively change the modulation multi-level number while improving the correction ability of the error correction code through the effect of time interleaving (cyclic interleaving in the embodiment).

[0050] (cyclic interleave) In the following, the cyclic interleaving according to the embodiment will be described. In Fig. 6, a case where the interval to which the cyclic interleaving is applied is one OFDM frame is illustrated. For the sake of simplicity, a case where one OFDM frame is composed of four subcarriers and five OFDM symbols is illustrated. s(x,y) represents an OFDM symbol, x represents the number of the OFDM symbol, and y represents the number of the subcarrier.

[0051] As shown in Fig. 6, the buffer 107 of the transmitting device 100 stores bits corresponding to OFDM symbols constituting one OFDM frame. The rearrangement unit 109 of the transmitting device 100 cyclically shifts the order of OFDM symbols (corresponding bits) in the time direction in symbol units according to the modulation multi-level number. For example, s(5,2) is cyclically shifted before s(1,2), s(4,3) and s(5.3) are cyclically shifted before s(1,3), and s(3,4), s(4,4) and s(5.4) are cyclically shifted before s(1,4). It should be noted that such cyclic shifts are completed within an interval.

[0052] (cyclic deinterleaving) In the following, the cyclic deinterleaving according to the embodiment will be described. In Fig. 7, the cyclic deinterleaving corresponding to the cyclic interleaving described in Fig. 6 is illustrated.

[0053] As shown in Fig. 7, the buffer 205 of the receiving device 200 stores bits corresponding to OFDM symbols constituting one OFDM frame. The rearrangement unit 207 of the receiving device 200 cyclically shifts the order of OFDM symbols (corresponding bits) in the time direction in symbol units according to the modulation multi-level number. For example, s(5,2) is cyclically shifted after s(4,2), s(4,3) and s(5.3) are cyclically shifted after s(3,3), and s(3,4), s(4,4) and s(5.4) are cyclically shifted after s(2,4). It should be noted that such cyclic shifts are completed within an interval.

[0054] (Variations) Variations of cyclic interleaving (cyclic deinterleaving) are described below. As shown in FIG. 8, the interval may be two OFDM frames.

[0055] As shown in FIG. 8, the buffer 107 of the transmitting device 100 stores bits corresponding to OFDM symbols constituting two OFDM frames. The rearrangement unit 109 of the transmitting device 100 cyclically shifts the order of OFDM symbols (corresponding bits) in the time direction in symbol units according to the modulation multi-level number. For example, s(5,2) of frame #n+1 is cyclically shifted before s(1,2) of frame #n, s(4,3) and s(5.3) of frame #n+1 are cyclically shifted before s(1,3) of frame #n, and s(3,4), s(4,4) and s(5.4) of frame #n+1 are cyclically shifted before s(1,4) of frame #n. It should be noted that such cyclic shifts are completed within an interval.

[0056] In FIG. 8, cyclic interleaving with an interval of 2 OFDM frames is illustrated. Since cyclic deinterleaving is the opposite process to cyclic interleaving, details thereof will be omitted. The interval may be 3 or more OFDM frames. That is, the interval may be a positive integer multiple of the OFDM frame.

[0057] In addition, parameters other than the modulation level (for example, coding rate and precoding weight) may be changeable for each OFDM frame, and adaptive control may be performed at the same frequency as in the past. In other words, it should be noted that while introducing a new function of applying cyclic interleaving (cyclic deinterleaving) in interval units, the impact on the conventional function is minimized.

[0058] (Example of operation) An example of the operation of the embodiment will be described below. As described above, the period during which the modulation multi-level number can be changed is determined according to the interval to which cyclic interleaving (cyclic deinterleaving) is applied. Here, the control information used to change the modulation multi-level number will be mainly described.

[0059] In the following, a case will be illustrated in which control information for the m-th OFDM frame is generated based on the reception quality of the (m-1)-th OFDM frame. The control information transmitted from the receiving device 200 to the transmitting device 100 is represented as DL (Down Link), and the OFDM frame transmitted from the transmitting device 100 to the receiving device 200 is represented as UL (Up Link). Furthermore, data stored in a buffer used in cyclic interleaving is represented as Bu. Here, a case will be illustrated in which an interval is composed of two OFDM frames. Also, a case will be illustrated in which a time division duplex (TDD) scheme is used.

[0060] Specifically, as shown in Figures 9 and 10, consider a case where interval #1 includes UL #1 and UL #2, interval #2 includes UL #3 and UL #4, and interval #3 includes UL #5 and UL #6. In this case, consider a case where the modulation level is changed from 8 bits (256QAM) to 6 bits (64QAM) by control information (DL #3 and UL #4) for UL #3 and UL #4 included in interval #2. Under this premise, the following options are considered as control information.

[0061] First, the first option will be described with reference to Fig. 9. In the first option, control information for an OFDM frame included in an nth interval (n is an integer equal to or greater than 1) includes an information element indicating a modulation multi-level number to be applied to a buffer used in cyclic interleaving in an n+xth interval (x is an integer equal to or greater than 0).

[0062] As shown in Fig. 9, even if the modulation multi-level number of the OFDM frame (UL#3) included in interval #2 is changed by the control information of DL#3, the cyclic interleaving for the OFDM frame transmitted in interval #2 uses the data (Bu#1) stored in the buffer before interval #2. Therefore, it may not be possible to immediately change the modulation multi-level number of the OFDM frame (UL#3) included in interval #2 by the control information of DL#3.

[0063] Therefore, the control information (DL#3) for the OFDM frame (UL#3) included in interval #2 includes an information element ([6 bits] in FIG. 9) indicating the modulation level to be applied to the data (Bu#2) stored in the buffer in interval #2. [6 bits] is an example of an information element indicating the modulation level to be applied to the buffer used in cyclic interleaving in the n+xth interval, where x is "0".

[0064] In the first option, the control information for the OFDM frame included in the n-th interval may include an information element indicating a modulation multi-level number to be applied to the OFDM frame included in the n-th interval. For example, the control information (DL#3) for the OFDM frame (UL#3) included in interval#2 may include an information element (8 bits in FIG. 9) indicating a modulation multi-level number to be applied to the OFDM frame (UL#3) included in interval#2. However, the control information does not have to include such an information element.

[0065] The period during which the modulation multi-level number can be changed is determined according to the interval to which cyclic interleaving is applied. Therefore, in the example shown in FIG. 9, it should be noted that the control information of DL#2, DL#4, and DL#6 is for UL#2, UL#4, and UL#6 (OFDM frames) in the middle of the interval, and therefore cannot be used to change the modulation multi-level number. In other words, the receiving device 200 may generate control information so that the information element indicating the modulation multi-level number is not changed between DL#1 and DL#2. Similarly, the receiving device 200 may generate control information so that the information element indicating the modulation multi-level number is not changed between DL#3 and DL#4, and the information element indicating the modulation multi-level number is not changed between DL#5 and DL#6.

[0066] When the receiving device 200 transmits control information including an information element indicating a modulation level to be applied to a buffer used in cyclic interleaving in the n+x-th interval, the receiving device 200 may execute cyclic deinterleaving assuming transmission of an OFDM frame using data stored in the buffer according to the modulation level. The timing at which the data stored in the buffer according to the modulation level is reflected in the OFDM frame may be predetermined by the digital wireless transmission system 10.

[0067] Secondly, the second option will be described with reference to Fig. 10. In the second option, the control information for the OFDM frame included in the nth interval (n is an integer equal to or greater than 1) includes an information element indicating the modulation multi-level number to be applied to the OFDM frame included in the n+yth interval (y is an integer equal to or greater than 1).

[0068] 10, even if the modulation multi-level number of the OFDM frame (UL#3) included in interval #2 is changed by the control information of DL#3, the cyclic interleaving for the OFDM frame transmitted in interval #2 uses the data (Bu#1) stored in the buffer before interval #2. Therefore, it may not be possible to immediately change the modulation multi-level number of the OFDM frame (UL#3) included in interval #2 by the control information of DL#3.

[0069] Therefore, the control information (DL#3) for the OFDM frame (UL#3) included in interval #2 includes an information element ([6 bits] in FIG. 10) indicating the modulation multi-level number to be applied to the OFDM frames (UL#5 and UL#6) included in interval #3. [6 bits] is an example of an information element indicating the modulation multi-level number to be applied to the OFDM frames included in the n+yth interval when y is "1".

[0070] In the second option, the control information for the OFDM frame included in the nth interval does not have to include an information element indicating a modulation level to be applied to the OFDM frame included in the nth interval, but the control information may include such an information element.

[0071] The period during which the modulation multi-level number can be changed is determined according to the interval to which cyclic interleaving is applied. Therefore, in the example shown in FIG. 9, it should be noted that the control information of DL#2, DL#4, and DL#6 is for UL#2, UL#4, and UL#6 (OFDM frames) in the middle of the interval, and therefore cannot be used to change the modulation multi-level number. In other words, the receiving device 200 may generate control information so that the information element indicating the modulation multi-level number is not changed between DL#1 and DL#2. Similarly, the receiving device 200 may generate control information so that the information element indicating the modulation multi-level number is not changed between DL#3 and DL#4, and the information element indicating the modulation multi-level number is not changed between DL#5 and DL#6.

[0072] When the receiving device 200 transmits control information including an information element indicating a modulation level to be applied to an OFDM frame included in the n+y-th interval, the receiving device 200 may execute cyclic deinterleaving assuming transmission of an OFDM frame to which a modulation level is applied. The timing at which the modulation level is reflected in the OFDM frame may be predetermined by the digital wireless transmission system 10.

[0073] (Action and Effects) In the embodiment, under the premise that the transmitting device 100 applies cyclic interleaving, the period for changing the modulation multi-level number is determined according to the interval for applying cyclic interleaving. With such a configuration, by adopting cyclic interleaving instead of convolutional interleaving and limiting the period for changing the modulation multi-level number by the interval, it is possible to adaptively change the modulation multi-level number while executing appropriate interleaving processing in the time direction.

[0074] In the embodiment, under the premise that the receiving device 200 applies cyclic deinterleaving, the period for changing the modulation multi-level number is determined according to the interval for applying cyclic deinterleaving. With such a configuration, by adopting cyclic deinterleaving instead of convolutional deinterleaving and limiting the period for changing the modulation multi-level number by the interval, it is possible to adaptively change the modulation multi-level number and perform appropriate deinterleaving processing.

[0075] In an embodiment, the control information for the OFDM frame included in the n-th interval may include an information element indicating a modulation multi-level number to be applied to a buffer used in cyclic interleaving in the n+x-th interval. With this configuration, the modulation multi-level number can be reflected in the OFDM frame at an appropriate timing, assuming a processing delay time including the time to store data in the buffer.

[0076] In an embodiment, the control information for the OFDM frame included in the n-th interval may include an information element indicating a modulation multi-level number to be applied to the OFDM frame included in the (n+y)-th interval. With this configuration, the modulation multi-level number can be reflected in the OFDM frame at an appropriate timing, assuming a processing delay time including the time required to store data in a buffer.

[0077] [Other embodiments] Although the present invention has been described by the above disclosure, the description and drawings forming a part of this disclosure should not be understood as limiting the present invention. From this disclosure, various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art.

[0078] In the above disclosure, the first and second options have been described as control information assuming a case where the modulation multi-level number cannot be changed immediately. However, the above disclosure is not limited to this. In a case where the modulation multi-level number can be changed immediately, the first and second options may not be applied. A case where the modulation multi-level number can be changed immediately may include a case where a buffer is provided in front of the S / P conversion unit 103 instead of the buffer 107 of the interleaving unit 105. In such a case, the buffer has a buffer size capable of storing transmission data equivalent to one interval or more. The transmitting device 200 completes a process of performing OFDM modulation by rearranging the transmission data equivalent to one interval by cyclic interleaving from the time when the control information is received until the OFDM frame to which the control information is applied is transmitted. In other words, the control information for the OFDM frame included in the n-th interval may include an information element indicating the modulation multi-level number to be applied to the OFDM frame included in the n-th interval. Even in such a case, the period during which the modulation multi-level number can be changed is determined according to the interval at which cyclic interleaving (cyclic deinterleaving) is applied.

[0079] In the above disclosure, the case where x is "0" in the first option is exemplified. However, the embodiment is not limited to this. When the processing delay time, including the time to store data in a buffer, is expected to be long, x may be an integer of 1 or more.

[0080] In the above disclosure, the case where y is "1" in the second option is exemplified. However, the embodiment is not limited to this. When the processing delay time, including the time to store data in a buffer, is expected to be long, y may be an integer of 2 or more.

[0081] In the above disclosure, a case has been described in which the control information includes an information element (MCS (Modulation Coding Scheme) parameter) that specifies a modulation level. However, the above disclosure is not limited to this. The control information may include parameters other than the MCS parameter (for example, parameters that specify a coding rate and a precoding weight). In the control information for the m-th OFDM frame, parameters other than the MCS parameter may be applied immediately to the m-th OFDM frame.

[0082] Although not particularly mentioned in the above disclosure, a program may be provided that causes a computer to execute each process performed by the transmitting device 100 and the receiving device 200. The program may also be recorded in a computer-readable medium. Using the computer-readable medium, it is possible to install the program in a computer. Here, the computer-readable medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, and may be, for example, a recording medium such as a CD-ROM or a DVD-ROM.

[0083] Alternatively, a chip may be provided that is configured by a memory that stores a program for executing each process performed by the transmitting device 100 and the receiving device 200, and a processor that executes the program stored in the memory. [Explanation of symbols]

[0084] 10...digital wireless transmission system, 100...transmitting device, 101...error correction coding section, 103...S / P conversion section, 105...interleaving section, 107...buffer, 109...rearrangement section, 111...OFDM modulation section, 113...control section, 200...receiving device, 201...OFDM demodulation section, 203...deinterleaving section, 205...buffer, 207...rearrangement section, 209...P / S conversion section, 211...error correction decoding section, 213...control section, 215...feedback section

Claims

1. a parallel conversion unit that converts a bit string constituting an error correction block into two or more parallel bit strings; an interleaving unit that applies cyclic interleaving to each of the two or more parallel bit strings output from the parallel conversion unit, the cyclic interleaving unit cyclically shifting each bit string in a time direction in symbol units corresponding to a modulation multi-level number; a modulation unit that modulates each of the two or more parallel bit strings output from the interleave unit in symbol units according to the modulation multi-level number, a period during which the modulation multi-level number can be changed is determined according to an interval during which the cyclic interleaving is applied, and is changed based on control information received from a receiving device; A transmitting device, wherein a change in the modulation multi-level number during the interval is limited.

2. A transmitting device as described in claim 1, wherein the control information for a frame included in the nth interval (n is an integer greater than or equal to 1) includes an information element indicating the modulation multi-value number to be applied to a buffer used in the cyclic interleaving in the n+xth interval (x is an integer greater than or equal to 0).

3. A transmitting device as described in claim 1, wherein the control information for a frame included in the nth interval (n is an integer greater than or equal to 1) includes an information element indicating the modulation multi-level number to be applied to the frame included in the n+yth interval (y is an integer greater than or equal to 1).

4. a demodulation unit that demodulates two or more parallel symbols corresponding to the number of subcarriers according to a modulation multi-level number, thereby outputting two or more parallel bit strings; a deinterleaving unit that applies cyclic deinterleaving to each of the two or more parallel bit strings output from the demodulation unit, the cyclic deinterleaving being performed in a time direction in symbol units corresponding to the modulation multi-level number; a serial conversion unit that converts two or more parallel bit strings output from the deinterleave unit into a serial bit string; a feedback unit for transmitting control information including an information element for specifying the modulation multi-level number, a period during which the modulation multi-value number can be changed is determined according to an interval at which the cyclic deinterleaving is applied, and is changed based on control information transmitted from the feedback unit; A receiving device, wherein a change in the modulation multi-level number during the interval is limited.

5. A receiving device as described in Claim 4, wherein the control information for a frame included in the nth interval (n is an integer greater than or equal to 1) includes an information element indicating the modulation multi-value number to be applied to a buffer used in cyclic interleaving in the n+xth interval (x is an integer greater than or equal to 0).

6. A receiving device as described in Claim 4, wherein the control information for a frame included in the nth interval (n is an integer greater than or equal to 1) includes an information element indicating the modulation multi-level number to be applied to the frame included in the n+yth interval (y is an integer greater than or equal to 1).

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