JP2022042893A - Transmitter, receiver and program - Google Patents

Abstract

To improve a transmission characteristic without reducing a transmission capacity.SOLUTION: A transmitter 1 includes: a reception status information receiver unit 14 which receives, from one or more receivers 2, reception status information indicating a reception state index value of each receiver 2; a mapping unit 15 which, based on the reception status information, selects a signal point coordinate table from a signal point coordinate storage unit 13, which stores a plurality of signal point coordinate tables in which bit data is associated with a signal point in an IQ plane, so as to map a bit data to an IQ plane according to the signal point coordinate table without changing a multi-valued number of carrier modulation to generate a carrier symbol; an OFDM frame configuration unit 18 which inserts a control signal into the carrier symbol to configure an OFDM frame; and an OFDM transmission processing unit 19 which performs OFDM modulation processing to the OFDM frame to generate an OFDM signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a transmitter, a receiver, and a program.

In the 3GPP (Third Generation Partnership Project), which formulates communication standards, 5G-MBMS (Multimedia Broadcast and Multicast. Service), which is multicast / broadcast transmission using 5G (5th Generation: 5th generation mobile communication system), is under consideration. It is being advanced. In 5G-MBMS, a mixed mode in which unicast transmission and multicast / broadcast transmission coexist between a base station and a receiving terminal is being studied (see, for example, Non-Patent Document 1).

Further, in the conventional LTE (Long Term Evolution) unicast transmission, the receiving terminal reports the CQI (Channel Quality Indicator) information to the base station, and the beam control of the base station and the selection of MCS (Modulation and Coding Scheme) are performed. (See, for example, Non-Patent Statement 2).

E. Garro, et al., “5G Mixed Mode: NR Multicast-Broadcast Services”, IEEE, March 2020 G. Ku and J. M. Walsh, “Resource Allocation and Link Adaptation in LTE and LTE Advanced: A Tutorial”, IEEE Communication Surveys & Tutorials, vol.17, No.3, Third Quarter 2015.

In conventional unicast transmission, when the reception condition is poor, that is, when the CQI value becomes small, a more resistant MCS is used. In MCS with strong tolerance, the resistance to noise and interference is increased by lowering the number of multiple values of carrier modulation and increasing the ratio (coding rate) of the information bit and parity bit to be transmitted, but the transmission capacity is high. There is a problem that it will decrease.

An object of the present invention made in view of such circumstances is to provide a transmitting device, a receiving device, and a program capable of improving transmission characteristics without lowering the transmission capacity.

The transmitting device according to one embodiment is a transmitting device that transmits an OFDM signal to a receiving device, and receives reception status information indicating a reception status index value of each receiving device from one or more receiving devices. A signal point coordinate table is selected from the signal point coordinate storage unit that stores a plurality of signal point coordinate tables that associate bit data with signal points on the IQ plane based on the reception status information, and multiple values of carrier modulation are selected. A mapping unit that maps bit data to the IQ plane according to the signal point coordinate table to generate a carrier symbol without changing the number, and an OFDM frame configuration unit that inserts a control signal into the carrier symbol to form an OFDM frame. And an OFDM transmission processing unit that performs OFDM modulation processing on the OFDM frame to generate an OFDM signal.

Further, the receiving device according to the embodiment is a receiving device that receives an OFDM signal from the transmitting device, and has an OFDM reception processing unit that demolishes the OFDM signal to generate a complex baseband signal, bit data, and an IQ plane. Select a signal point coordinate table from the signal point coordinate storage unit that stores a plurality of signal point coordinate tables associated with the above signal points, and the signal point coordinates based on the signal point coordinate table and the signal point coordinates of the complex baseband signal. The LLR calculation unit that calculates the LLR for each bit, the error correction / decoding unit that performs error correction / decoding using the LLR, and the error correction / decoding unit that generates a received signal, and the reception that indicates the reception status index value of the receiving device. It includes a reception status information transmission unit that transmits status information to the transmission device.

Further, the program according to the embodiment causes the computer to function as the transmission device.

Further, the program according to the embodiment causes the computer to function as the receiving device.

According to the present invention, it is possible to improve the transmission characteristics without lowering the transmission capacity.

It is a block diagram which shows the structural example of the transmission apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the operation example of the transmission device which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the receiving apparatus which concerns on one Embodiment of this invention. It is a flowchart which shows the operation example of the receiving apparatus which concerns on one Embodiment of this invention. It is a figure which shows the 1st comparative example of BER in this invention and a conventional method. It is a figure which shows the 2nd comparative example of BER in this invention and the conventional method. It is a figure which shows the 3rd comparative example of BER in this invention and the conventional method. It is a figure for demonstrating the selection example of the signal point coordinate table of the transmission apparatus which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

(Transmitter)
FIG. 1 is a block diagram showing a configuration example of a transmission device according to an embodiment. The transmission device 1 shown in FIG. 1 includes an error correction coding unit 11, a bit interleaving unit 12, a signal point coordinate storage unit 13, a reception status information receiving unit 14, a mapping unit 15, and a time / frequency interleaving unit 16. A control signal generation unit 17, an OFDM (Orthogonal Frequency Division Multiplexing) frame configuration unit 18, and an OFDM transmission processing unit 19 are provided.

The transmission device 1 may be a device that performs unicast transmission, a device that performs multicast / broadcast transmission, or a device that supports a mixed mode in which unicast transmission and multicast / broadcast transmission coexist. There may be. The transmitting device 1 may be a broadcasting station (transmitting station) or a base station. The transmission device 1 may be composed of one or more semiconductor chips.

The error correction coding unit 11 performs error correction coding (for example, LDPC coding) of a transmission signal input from the outside of the transmission device 1 in order to enable correction of transmission errors on the receiving side, and generates a coded signal. do. Then, the error correction coding unit 11 outputs the generated coded signal to the bit interleaving unit 12.

The bit interleaving unit 12 generates bit data by interleaving the coded signal input from the error correction coding unit 11 in bit units in order to improve the performance of the error correction code. Then, the bit interleaving unit 12 outputs the generated bit data to the mapping unit 15.

The signal point coordinate storage unit 13 stores a plurality of signal point coordinate tables that associate bit data with signal points on the IQ plane in advance. Table 1 below shows an example of a signal point coordinate table when the carrier modulation method is 256QAM. Here, the lower 6 bits (b ₂ , b- ₃ , b ₄ , b- ₅ , b ₆ , b- ₇ ) are from (0,0,0,0,0,0) to (1,1,1, In the case of 1, 1, 1), the signal point coordinates on the I axis and the signal point coordinates on the Q axis are shown. Non-Uniform A (first table) in Table 1 is a first signal point coordinate table used in the present invention, and Non-Uniform B (second table) is a second signal point coordinate table used in the present invention. It is a signal point coordinate table of. The spacing between the signal points arranged according to the first signal point coordinate table and the second signal point coordinate table is non-uniform. On the other hand, the Uniform in Table 1 is a conventional signal point coordinate table for making the signal point spacing uniform, and is shown for comparison, and is not used in the present invention.

The signal point coordinate table is a BICM (bit-interleaved coded modulation:) obtained by the following equation (1), assuming a specific value as the CNR (Carrier to Noise Ratio) of the transmission line. Bit interleaved coded modulation) Designed (adjusted) to maximize capacity C _B. If the CNR of the transmission line is known, it is designed so that the _BICM capacity CB is maximized in the CNR. Non-Uniform A is a signal point coordinate table designed to maximize BICM capacity C _B near CNR = 20 dB, and Non-Uniform B has maximum BICM capacity C _B near CNR = 23 dB. It is a signal point coordinate table designed in. For details of BICM capacity, refer to, for example, Reference 1 and Reference 2 below.
[Reference 1] J. Zoellner and N. Loghin, “Optimization of High-order Non-uniform QAM Constellations”, in Proc. IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, pp. 1-6, June 2013
[Reference 2] G. Caire, G. Taricco and E. Biglieri, “Capacity of bit-interleaved channels”, IEE Electronics Letters., Vol. 32, no.12, June 1996

The reception status information receiving unit 14 receives reception status information indicating a reception status index value of each receiving device from one or more receiving devices described later. The reception status information receiving unit 14 outputs the received reception status information to the mapping unit 15. Here, the reception status index value is a physical layer measurement value related to the reception status in the receiving device, and is SS (Synchronization Signal) -SINR (Signal to Interference plus Noise Ratio), CSI. (Channel State Information) -SINR, MER (Modulation Error Ratio), EVM (Error Vector Magnitude), error detection rate, etc. In addition, SS-RSRP (Reference Signal Received Power), CSI-RSRP, SS-RSRQ (Reference Signal Received Quality), CSI-RSRQ, and the like may be used. For an example of the physical layer measurement value, refer to Reference 3 below, for example.
[Reference 3] “Physical layer measurements”, ETSI, 3GPP TS 38.215, version 15.2.0 Release 15, 2018-07

The mapping unit 15 selects one signal point coordinate table from the signal point coordinate storage unit 13 based on the reception status information input from the reception status information reception unit 14. For example, the mapping unit 15 is a signal point coordinate storage unit according to a comparison result between a value based on the reception status index value indicated by the reception status information (worst value, average value, etc. of the reception status index value) and a predetermined threshold value. Select the signal point coordinate table from 13. When the transmitting device 1 performs multicast / broadcast transmission, it is transmitted to a plurality of receiving devices distributed in the communication area (cover area, reception area) using a common signal point coordinate table, and is the same. It is necessary to cover the communication area with the signal point coordinate table. Therefore, it is preferable that the mapping unit 15 obtains the average value of the reception status index values acquired from the receiving device and selects the signal point coordinate table according to the comparison result with the predetermined threshold value.

Then, the mapping unit 15 does not change the multi-valued number of carrier modulation as in the conventional method, but the bit data I of the bit data input from the bit interleaving unit 12 according to the signal point coordinate table selected from the signal point coordinate storage unit 13. The coordinates on the axis and the coordinates on the Q axis are determined and mapped to the IQ plane (complex plane) to generate a carrier symbol. The mapping unit 15 outputs the generated carrier symbol to the time / frequency interleave unit 16.

The mapping unit 15 may output a signal point coordinate parameter indicating the selected signal point coordinate table to the control signal generation unit 17. That is, whether or not the transmitting device 1 transmits to the receiving device as a control signal which signal point coordinate table was used to transmit the OFDM signal can be arbitrary.

The upper 2 bits (b ₀ , b- ₁ ) of the bits transmitted by mapping represent the quadrant of the constellation. For example, the technical specifications of 3GPP (see "5.1 Modulation mapper" in Reference 4 below) and the transmission method ISDB-T for Japanese terrestrial digital broadcasting (see "3.9.3 Bit Interleaving and Mapping" in Reference 5 below). (See)), as shown in Table 2 below.
[Reference 4] “Physical channels and modulation”, ETSI, 3 GPP TS 38.211, version 15.2.0 Release 15, 2018-07
[Reference 5] "Transmission method for terrestrial digital television broadcasting", ARIB, STD-B31

Alternatively, for (b ₀ , b- ₁ ), the transmission method ATSC3.0 for terrestrial digital broadcasting in the United States (“6.3.4 Bit to IQ Mapping” in Reference 6 below) is shown in Table 3 below. You may do so.
[Reference 6] “Physical Layer Protocol (A / 322)”, ATSC, 2017

The time / frequency interleaving unit 16 rearranges the order of the carrier symbols input from the mapping unit 15 in the time direction and the frequency direction to generate an interleaved signal. Then, the time / frequency interleaving unit 16 outputs the generated interleaving signal to the OFDM frame component unit 18.

The control signal generation unit 17 generates a control signal including transmission parameters such as a carrier modulation method, an error correction coding rate, and a time interleave length. The control signal may include a signal point coordinate parameter indicating a signal point coordinate table selected by the mapping unit 15. Then, the control signal generation unit 17 outputs the generated control signal to the OFDM frame configuration unit 18.

The OFDM frame configuration unit 18 constructs an OFDM frame by inserting a pilot signal and a control signal input from the control signal generation unit 17 into the interleave signal input from the time / frequency interleave unit 16. Then, the OFDM frame configuration unit 18 outputs the generated OFDM frame to the OFDM transmission processing unit 19.

The OFDM transmission processing unit 19 performs OFDM modulation processing on the OFDM frame input from the OFDM frame configuration unit 18 to generate an OFDM signal, and transmits the generated OFDM signal to the receiving device. More specifically, the OFDM transmission processing unit 19 performs IFFT (Inverse Fast Fourier Transform) processing on the OFDM symbol of the OFDM frame input from the OFDM frame configuration unit 18, and is an effective symbol in the time region. Generate a signal. Then, the OFDM transmission processing unit 19 inserts a guard section called a cyclic prefix (CP) at the beginning of the effective symbol signal, and then performs quadrature modulation processing and D / A conversion processing to generate an OFDM signal. do.

Next, the operation of the transmission device 1 will be described with reference to FIG. FIG. 2 is a flowchart showing an operation example of the transmission device 1.

In step S101, the error correction coding unit 11 performs error correction coding processing on the transmission signal to generate a coded signal, and the processing proceeds to step S102.

In step S102, the bit interleaving unit 12 performs bit interleaving processing on the coded signal to generate bit data, and the processing proceeds to step S103.

In step S103, the reception status information receiving unit 14 receives the reception status information, and the process proceeds to step S104.

In step S104, the mapping unit 15 selects the signal point coordinate table from the signal point coordinate storage unit 13, and the process proceeds to step S105.

In step S105, the mapping unit 15 maps the bit data to the IQ plane according to the selected signal point coordinate table to generate the carrier symbol without changing the multi-valued number of carrier modulation, and proceeds to the process in step S106.

In step S106, the time / frequency interleaving unit 16 performs time / frequency interleaving processing on the carrier symbol to generate an interleaving signal, and the processing proceeds to step S107.

In step S107, the control signal generation unit 17 generates a control signal, and the process proceeds to step S108.

In step S108, the OFDM frame component 18 inserts a pilot signal and a control signal into the interleave signal to form an OFDM frame, and the process proceeds to step S109.

In step S109, the OFDM transmission processing unit 19 performs OFDM modulation processing on the OFDM frame to generate an OFDM signal.

(Receiver)
Next, the receiving device according to the embodiment will be described.

FIG. 3 is a block diagram showing a configuration example of the receiving device according to the embodiment. The receiving device 2 shown in FIG. 3 includes an OFDM reception processing unit 21, a SINR calculation unit 22, a signal extraction unit 23, a propagation path response estimation unit 24, a control signal demodulation unit 25, and an equalization processing unit 26. The time / frequency deinterleave unit 27, the signal point coordinate storage unit 28, the MER / EVM calculation unit 29, the LLR (Log-likelihood ratio) calculation unit 30, the bit deinterleave unit 31, and the error correction / decoding unit 32. , A reception status information transmission unit 33.

The receiving device 2 may include only one of the SINR calculation unit 22 and the MER / EVM calculation unit 29. The receiving device 2 may be a television receiver, a PC, or a smartphone. The receiving device 2 may be composed of one or more semiconductor chips.

The OFDM reception processing unit 21 receives the OFDM signal transmitted from the transmission device 1, demodulates it to generate a complex baseband signal, and uses the generated complex baseband signal as the SINR calculation unit 22, the signal extraction unit 23, and the like. It is output to the conversion processing unit 26. More specifically, the OFDM reception processing unit 21 performs orthogonal demodulation processing and A / D conversion processing on the received OFDM signal to generate a digital signal. Then, the OFDM reception processing unit 21 removes the cyclic prefix and extracts the valid symbol signal. Next, the OFDM reception processing unit 21 performs FFT (Fast Fourier Transform) processing on the effective symbol signal to generate a complex baseband signal.

The SINR calculation unit 22 calculates SINR such as SS-SINR and CSI-SINR for the complex baseband signal input from the OFDM reception processing unit 21. Then, the SINR calculation unit 22 outputs the calculated SINR to the reception status information transmission unit 33.

The signal extraction unit 23 extracts a pilot signal and a control signal from the complex baseband signal input from the OFDM reception processing unit 21. Then, the signal extraction unit 23 outputs the extracted pilot signal to the propagation path response estimation unit 24, and outputs the extracted control signal to the control signal demodulation unit 25.

The propagation path response estimation unit 24 estimates the propagation path response for each carrier based on the pilot signal input from the signal extraction unit 23 and the preset pilot signal. Then, the propagation path response estimation unit 24 outputs the propagation path response for each carrier to the equalization processing unit 26.

The equalization processing unit 26 performs equalization processing of the complex baseband signal input from the OFDM reception processing unit 21 using the propagation path response input from the propagation path response estimation unit 24, and corrects the propagation path distortion. Then, the equalization processing unit 26 outputs the equalized complex baseband signal (equalization signal) to the time / frequency deinterleaved unit 27.

The control signal demodulation unit 25 demodulates the control signal input from the signal extraction unit 23 to extract transmission parameters such as a carrier modulation method, an error correction coding rate, and a time interleave length. Then, the control signal demodulation unit 25 outputs the extracted transmission parameters to the time / frequency deinterleave unit 27, the bit deinterleave unit 31, and the error correction / decoding unit 32. When the extracted transmission parameter includes the signal point coordinate parameter, the control signal demodulation unit 25 outputs the signal point coordinate parameter to the MER / EVM calculation unit 29 and the LLR calculation unit 30.

The time / frequency deinterleave unit 27 performs deinterleave processing in the frequency direction and the time direction with respect to the equalization signal input from the equalization processing unit 26, and generates a deinterleave signal. The frequency direction deinterleave processing is a process of returning the data sorted in the frequency direction by the time / frequency interleaving unit 16 of the transmission device 1 to the original order. The deinterleaving process in the time direction is a process of returning the data sorted in the time direction by the time / frequency interleaving unit 16 of the transmission device 1 to the original order. Then, the time / frequency deinterleave unit 27 outputs the deinterleave signal to the MER / EVM calculation unit 29 and the LLR calculation unit 30.

Similar to the signal point coordinate storage unit 13 of the transmission device 1, the signal point coordinate storage unit 28 stores a plurality of signal point coordinate tables for associating bit data with signal points on the IQ plane in advance.

The MER / EVM calculation unit 29 selects a signal point coordinate table from the signal point coordinate storage unit 28, and the signal point coordinates based on the selected signal point coordinate table and the deinterleave signal input from the time / frequency deinterleave unit 27. The MER (modulation error ratio) and / or EVM (error vector amplitude) of the deinterleaved signal is calculated by comparing with the signal point coordinates. Then, the MER / EVM calculation unit 29 outputs the calculated MER and / or EVM to the reception status information transmission unit 33. The MER / EVM calculation unit 29 may calculate the MER and / or EVM using the input signal to the time / frequency deinterleave unit 27 (the equalization signal output by the equalization processing unit 26).

The LLR calculation unit 30 selects a signal point coordinate table from the signal point coordinate storage unit 28, and the signal point coordinates based on the selected signal point coordinate table and the signal point of the deinterleave signal input from the time / frequency deinterleave unit 27. Compare with the coordinates and calculate LLR (log likelihood ratio) for each bit based on the Euclidean distance of both coordinates. Then, the LLR calculation unit 30 outputs the calculated LLR to the bit deinterleave unit 31.

The method of selecting the signal point coordinate table in the MER / EVM calculation unit 29 and the LLR calculation unit 30 is as follows. When the control signal demodulated by the control signal demodulation unit 25 includes a signal point coordinate parameter, the signal point coordinate table indicated by the signal point coordinate parameter is selected from the signal point coordinate storage unit 28.

On the other hand, when the control signal demodulated by the control signal demodulation unit 25 does not include the signal point coordinate parameter, the signal point coordinate storage unit 28 is based on the comparison result between the reception status index value and the predetermined threshold value. Select one signal point coordinate table from. The reception status index value is the SINR value calculated by the SINR calculation unit 22 when the reception device 2 includes the SINR calculation unit 22, and the reception device 2 includes the MER / EVM calculation unit 29. In the case, it is the value of MER or EVM calculated by the MER / EVM calculation unit 29. When the receiving device 2 includes the SINR calculation unit 22 and the MER / EVM calculation unit 29, it is one or a plurality of values of SINR, MER, and EVM. If the control signal demodulated by the control signal demodulation unit 25 does not include the signal point coordinate parameter, an error is made after trying all the signal point coordinate tables stored in the signal point coordinate storage unit 28. One signal point coordinate table that minimizes the error detection rate obtained by the correction / decoding unit 32 or the error rate of the transport block may be selected.

The bit deinterleave unit 31 performs deinterleave processing in the bit direction on the LLR corresponding to each bit input from the LLR calculation unit 30, and generates a bit deinterleave signal. This deinterleave process is a process of returning the data rearranged by the bit interleave unit 12 of the transmission device 1 to the original order.

The error correction decoding unit 32 performs error correction decoding (for example, LDPC decoding) using the bit deinterleave signal input from the bit deinterleave unit 31, decodes the signal transmitted from the transmission device 1, and generates a received signal. do. Further, the error correction / decoding unit 32 may calculate the error detection rate by CRC (Cyclic Redundancy Check). Then, the error correction / decoding unit 32 outputs the generated reception signal to the outside, and outputs the calculated error detection rate to the reception status information transmission unit 33.

The reception status information transmission unit 33 transmits the reception status information indicating the reception status index value of the reception device 2 to the transmission device 1. In the present embodiment, the reception status index value is the SINR calculated by the SINR calculation unit 22, the MER and EVM calculated by the MER / EVM calculation unit 29, and the error detection rate calculated by the error correction / decoding unit 32. Although it is one or more of them, the reception status index value is not limited to this.

Next, the operation of the receiving device 2 will be described with reference to FIG. FIG. 4 is a flowchart showing an operation example of the receiving device 2.

In step S201, the OFDM reception processing unit 21 performs OFDM reception processing on the OFDM signal to generate a complex baseband signal, and the processing proceeds to step S202.

In step S202, the SINR calculation unit 22 calculates the SINR of the complex baseband signal, and the reception status information transmission unit 33 transmits the SINR as reception status information to the transmission device 1, and the process proceeds to step S203.

In step S203, the signal extraction unit 23 extracts the pilot signal and the control signal from the complex baseband signal, and proceeds to the process in step S204. The processes of steps S202 and S203 may be performed at the same time, or the processes of step S203 may be performed first.

In step S204, the propagation path response is estimated by the propagation path response estimation unit 24, and the equalization processing unit 26 performs equalization processing on the complex baseband signal using the propagation path response to generate an equalization signal. Then, the process proceeds to step S205.

In step S205, the time / frequency deinterleave unit 27 performs a time / frequency deinterleave process on the equalized signal to generate a deinterleave signal, and the process proceeds to step S206.

In step S206, the MER / EVM calculation unit 29 and the LLR calculation unit 30 select a signal point coordinate table from the signal point coordinate storage unit 28, and the process proceeds to step S207.

In step S207, the MER / EVM calculation unit 29 compares the signal point coordinates based on the selected signal point coordinate table with the signal point coordinates of the deinterleaved signal, calculates the MER / EVM of the deinterleaved signal, and receives reception status information. The transmission unit 33 transmits the MER / EVM as reception status information to the transmission device 1, and advances the process to step S208.

In step S208, the LLR calculation unit 30 compares the signal point coordinates based on the selected signal point coordinate table with the signal point coordinates of the deinterleaved signal, calculates the LLR for each bit, and proceeds to step S209. The processes of steps S207 and S208 may be performed at the same time, or the processes of step S208 may be performed first.

In step S209, the bit deinterleave unit 31 performs bit deinterleave processing on the LLR to generate a bit deinterleave signal, and the processing proceeds to step S210.

In step S210, the error correction / decoding unit 32 performs error correction / decoding processing on the bit deinterleaved signal to generate a received signal. Further, the error correction / decoding unit 32 calculates the error detection rate, and the reception status information transmission unit 33 transmits the error detection rate to the transmission device 1 as reception status information.

(Bit error rate characteristics)
Next, the bit error rate characteristic (BER) of the present invention will be described in comparison with the conventional method.

5 to 7 are diagrams showing a comparative example of BER between the present invention and the conventional method. Here, the BER is shown when the MCS index is 20 (that is, when the modulation method is 256QAM and the coding rate is 682.5 / 1024). For details of the MCS index, refer to, for example, Table 5.1.3.1-2 MCS index table 2 for PDSCH in Reference 7 below.
[Reference 7] “Physical layer procedures for data”, ETSI, 3GPP TS 38.214, Version 15.3.0 Release 15, 2018-10

In FIGS. 5 to 7, the horizontal axis is CNR (dB) and the vertical axis is BER. Non-Uniforms A and B in the figure indicate BERs when the signal point coordinate tables of Non-Uniforms A and B shown in Table 1 are used in the transmitting device 1 and the receiving device 2 according to the present invention. Shows the BER when the Uniform shown in Table 1 is used in the conventional method.

FIG. 5 shows a BER when the MCS index is 20 and the environment is an AWGN (Additive white Gaussian Noise) environment. From FIG. 5, it can be seen that in the AWGN environment, the BER curve according to the present invention is located on the left side of the conventional method, the transmission characteristics are improved, and Non-Uniform A is the best.

FIG. 6 shows a BER when the MCS index is 20 and the environment is a multipath environment of a two-wave model and the DUR (Desired signal to. Undesired signal Ratio) is 3 dB. From FIG. 6, it can be seen that the present invention has better characteristics than the conventional method in an environment where the DUR of the multipath interference wave is 3 dB. Further, the characteristics of Non-Uniform A and Non-Uniform B are almost the same.

FIG. 7 shows a BER when the MCS index is 20, the environment is a two-wave model multipath environment, and the DUR is 0 dB. From FIG. 7, it can be seen that even in an environment where the DUR is 0 dB, the present invention has better characteristics than the conventional method, and Non-Uniform B is the best.

From the above, it can be seen that the transmission characteristics can be improved by changing the signal point coordinate table according to the reception status. It can also be seen that the best signal point coordinates in an ideal AWGN environment and the best signal point coordinates in a poor environment such as a multipath environment with a DUR of 0 dB are different.

The CNR and the reception status index values such as SINR, MER, and EVM have a correlation and can be regarded as almost the same. Therefore, for example, when Non-Uniform B is a signal point coordinate table designed so that BICM capacity C _B is maximized near CNR = 23 dB, the mapping unit 15 uses 23 dB as a threshold value and is a reception status index in the communication area. It is conceivable to use Non-Uniform A when the worst value is less than 23 dB, and to use Non-Uniform B when it is 23 dB or more. Alternatively, the average value of the reception status index values in the communication area may be used as a reference instead of the worst value of the reception status index values in the communication area.

FIG. 8 is a diagram for explaining a selection example of the signal point coordinate table of the transmission device 1. FIG. 8 shows a base station as the transmission device 1. Further, as the receiving device 2, the receiving terminals UE (User Equipment) 1, UE2, and UE3 arranged in the communication area (communication area of Non-Uniform) when the non-uniform signal point coordinates are used are shown. The transmitting device 1 does not need to know the information of whether the environment is the AWGN environment or the DUR is what dB in the multipath environment, and the transmitting device 1 selects the signal point coordinate table based on the reception status index value.

As a first example, it is assumed that the SINR of UE1 is 30 dB, the SINR of UE2 is 25 dB, and the SINR of UE3 is 20.2 dB, which is an AWGN environment. From the result of FIG. 5, an error occurs when the signal point coordinate table of Uniform and Non-Uniform B is used, but data can be received without error by using the signal point coordinate table of Non-Uniform A. When the worst value of SINR in the communication area is used as a reference, the worst value is 20.2 dB (UE3), and when this value is smaller than 23 dB, communication is performed by selecting the signal point coordinate table of Non-Uniform A. The area can be expanded.

As a second example, it is assumed that the SINR of UE1 is 30 dB, the SINR of UE2 is 25 dB, the SINR of UE3 is 23.6 dB, and the DUR of the multipath interference wave is 0 dB. From the result of FIG. 7, an error occurs when the signal point coordinate table of Uniform and Non-Uniform A is used, but data can be received without error by using the signal point coordinate table of Non-Uniform B. When the worst value of SINR in the communication area is used as a reference, the worst value is 23.6 dB (UE3), and when this value is 23 dB or more, communication is performed by selecting the signal point coordinate table of Non-Uniform B. The area can be expanded.

As described above, the mapping unit 15 of the transmission device 1 does not change the multi-value number of the carrier modulation or the coding rate according to the reception status information of the reception device 2, but when the reception status deteriorates. Change only the non-uniform signal point arrangement of carrier modulation. Therefore, according to the present invention, when the reception condition is poor, the transmission characteristics are greatly improved and the communication area is expanded in the AWGN environment and the multipath environment as compared with the conventional uniform mapping method without reducing the transmission capacity. It becomes possible.

(program)
It is also possible to use a computer capable of executing program instructions in order to function as the transmission device 1 or the reception device 2. The computer stores a program describing the processing contents that realize each function of the transmitting device 1 or the receiving device 2 in the storage unit of the computer, and the processor of the computer reads and executes this program. Some of these processing contents may be realized by hardware. Here, the computer may be a general-purpose computer, a dedicated computer, a workstation, a PC (Personal Computer), an electronic notepad, or the like. The program instruction may be a program code, a code segment, or the like for executing a necessary task. The processor may be a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), a DSP (Digital Signal Processor), or the like.

For example, the program for functioning as the transmission device 1 causes the computer to execute each step shown in FIG. Further, the program for functioning as the receiving device 2 causes the computer to execute each step shown in FIG.

The program may also be recorded on a computer-readable recording medium. Using such a recording medium, it is possible to install the program on the computer. Here, the recording medium on which the program is recorded may be a non-transient recording medium. The non-transient recording medium is not particularly limited, but may be, for example, a recording medium such as a CD-ROM or a DVD-ROM. The program can also be provided by download over the network.

Although the above embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the invention should not be construed as limiting by the embodiments described above, and various modifications or modifications can be made without departing from the claims. For example, it is possible to combine a plurality of the constituent blocks described in the configuration diagram of the embodiment into one, or to divide one constituent block into one.

1 Transmitter 2 Receiver 11 Error correction coding unit 12-bit interleaving unit 13 Signal point coordinate storage unit 14 Reception status information receiving unit 15 Mapping unit 16 Time / frequency interleaving unit 17 Control signal generation unit 18 OFDM frame configuration unit 19 OFDM transmission Processing unit 21 OFDM reception processing unit 22 SINR calculation unit 23 Signal extraction unit 24 Propagation path response estimation unit 25 Control signal demodulation unit 26 Equalization processing unit 27 Time / frequency deinterleavement unit 28 Signal point coordinate storage unit 29 MER / EVM calculation unit 30 LLR calculation unit 31 Bit orthogonal leave unit 32 Error correction decoding unit 33 Reception status information transmission unit

Claims (14)

A transmitter that transmits an OFDM signal to a receiver.
A reception status information receiving unit that receives reception status information indicating a reception status index value of each receiving device from one or more receiving devices.
Select the signal point coordinate table based on the reception status information from the signal point coordinate storage unit that stores multiple signal point coordinate tables that associate bit data with the signal points on the IQ plane, and change the number of multi-values for carrier modulation. A mapping unit that maps bit data to the IQ plane according to the signal point coordinate table to generate a carrier symbol without using the above.
An OFDM frame component that constitutes an OFDM frame by inserting a control signal into the carrier symbol,
An OFDM transmission processing unit that performs OFDM modulation processing on the OFDM frame to generate an OFDM signal, and
A transmitter equipped with. The transmission device according to claim 1, wherein the mapping unit selects the signal point coordinate table from the signal point coordinate storage unit according to a comparison result between a value based on the reception status index value and a predetermined threshold value. .. The transmitter according to claim 1 or 2, wherein the intervals between the signal points arranged according to the signal point coordinate table are non-uniform. The transmitter according to any one of claims 1 to 3, wherein the signal point coordinate table is designed so as to maximize the BICM capacity when a certain value is assumed as the CNR of the transmission line. .. When the carrier modulation method is 256QAM, the plurality of signal point coordinate tables for associating the lower 6 bits of the bit data with the signal points on the IQ plane are shown in the table below.

4. The transmitter according to claim 4, comprising the first table and the second table of the above. The transmission device according to any one of claims 1 to 5, wherein the control signal includes a parameter indicating the signal point coordinate table selected by the mapping unit. A receiving device that receives an OFDM signal from a transmitting device.
An OFDM reception processing unit that demodulates the OFDM signal to generate a complex baseband signal,
A signal point coordinate table is selected from the signal point coordinate storage unit that stores a plurality of signal point coordinate tables that associate bit data with signal points on the IQ plane, and the signal point coordinates based on the signal point coordinate table and the complex base band are used. The LLR calculation unit that compares the signal point coordinates of the signal and calculates the LLR for each bit,
An error correction / decoding unit that performs error correction / decoding using the LLR and generates a received signal,
A reception status information transmission unit that transmits reception status information indicating a reception status index value of the reception device to the transmission device, and a reception status information transmission unit.
A receiver equipped with. The receiving device according to claim 7, wherein the reception status index value is the SINR, MER, EVM of the complex baseband signal, or the error detection rate obtained by the error correction / decoding unit. When the control signal received from the transmission device includes a signal point coordinate parameter, the LLR calculation unit selects the signal point coordinate table indicated by the signal point coordinate parameter from the signal point coordinate storage unit. The receiving device according to claim 7 or 8. When the control signal received from the transmission device does not include the signal point coordinate parameter, the LLR calculation unit has the signal point coordinates based on the comparison result between the reception status index value and a predetermined threshold value. The receiving device according to any one of claims 7 to 9, wherein the signal point coordinate table is selected from the storage unit. When the control signal received from the transmission device does not include the signal point coordinate parameter, the LLR calculation unit tests all the signal point coordinate tables stored in the signal point coordinate storage unit, and then tries them. The receiving device according to any one of claims 7 to 9, wherein the signal point coordinate table that minimizes the error detection rate obtained by the error correction decoding unit or the error rate of the transport block is selected. When the carrier modulation method of the OFDM signal is 256QAM, the plurality of signal point coordinate tables for associating the lower 6 bits of the bit data with the signal points on the IQ plane are shown in the table below.

The receiving device according to any one of claims 7 to 11, comprising the first table and the second table of the above. A program for operating a computer as the transmitting device according to any one of claims 1 to 6. A program for operating a computer as a receiving device according to any one of claims 7 to 12.

Images