JP2007306423A - Radio communication device and data transmission method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a radio communication device by which highly efficient communication is attained. <P>SOLUTION: The radio communication device concerning the present invention transmits data by using a coding system and a modulation system which are selected and determined according to a state of a transmission path and re-transmits data (packet) which becomes a transmission error in a re-transmission allowance period allowed by a device at a transmitting destination when the transmission error occurs and has an AMC set selection part (2) which selects an AMC set which is combination of the coding system and the modulation system based on the re-transmission allowance period and the state of the transmission path when the transmission error occurs and a signal transmitting part (3) which re-transmits the data which becomes the transmission error by using the AMC set selected by the AMC set selection part (2). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a wireless communication apparatus that performs packet communication, and in particular, a wireless communication apparatus that efficiently transmits data while changing a transmission rate according to the state of a transmission path, and data used by the wireless communication apparatus It relates to a transmission method.

  A number of technical disclosures have been made so far about adaptive modulation schemes that switch the number of modulation levels and the coding rate (used for error correction) in accordance with transmission path fluctuations of a radio line. For example, Patent Document 1 below discloses a method of starting communication at a low rate with respect to an optimal transmission mode calculated from a transmission path state and gradually shifting to a higher rate. In Patent Document 2 below, a method of changing a target error rate corresponding to a transmission path state that fluctuates at high speed and controlling a modulation scheme and a coding rate is disclosed.

JP-A-2005-72878 JP 2005-86304 A

  A conventional packet radio communication apparatus measures the state of a changing transmission path, and combines a modulation scheme and a coding rate (hereinafter, these modulation schemes and coding rates are combined to achieve a predetermined target quality (error rate). AMC (Adaptive Modulation and Coding) set).

  In recent years, attempts have been made to realize highly efficient communication by managing the characteristics and quality of data passing through a wireless line. In particular, services that perform high-quality real-time data transmission by defining an allowable delay time of data to be transmitted and guaranteeing the delay time are attracting attention. In these communications, if an error occurs in a part of the transmitted data packet, only the packet in which the error has occurred is retransmitted, while other packets (packets that arrive without error) are buffered on the receiving side. Is done. When all packets including packets retransmitted by the allowable delay time arrive, the data is sent to the upper layer all at once, but if all packets do not arrive by the allowable delay time, the buffered data is included. The packet is discarded and a communication error occurs. In other words, in data transmission in which the delay time is specified, all packets need only arrive at the receiving side by the specified time.

  However, in a conventional wireless communication device represented by the wireless communication device described in Patent Document 1 or 2, the AMC set is specified based on the quality of data (or due to restrictions on the device configuration such as buffer size). The allowable delay time was not considered. By setting an error rate that achieves sufficient allowable delay time as a target value, there are cases where it is indirectly considered, but this error rate is uniform and positively uses the allowable delay time. It was not the composition that was done. Therefore, a lower rate AMC set is selected, and there is a problem that data transmission with sufficiently improved line efficiency cannot be realized.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a wireless communication apparatus that realizes highly efficient communication by positively using information on the allowable delay time of transmission data.

  In order to solve the above-described problems and achieve the object, the present invention transmits data using an encoding method and a modulation method selected and determined according to the transmission path state, and when a transmission error occurs, A wireless communication apparatus that retransmits data (packet) that has caused a transmission error within a period allowed by a transmission destination apparatus (retransmission allowable period), and is based on the retransmission allowable period and the transmission path state when a transmission error occurs. AMC set selection means for selecting an AMC set which is a combination of the encoding scheme and the modulation scheme; and a retransmission means for retransmitting data having a transmission error using the AMC set selected by the AMC set selection means; It is characterized by providing.

  According to the present invention, transmission is performed using an encoding method and a modulation method that provide a high transmission rate while there is a retransmission opportunity, and when there is no retransmission opportunity, a sufficiently low transmission rate with sufficient redundancy is provided. Since transmission is performed using a method and a modulation method, there is an effect that highly efficient and reliable data transmission can be realized.

  Embodiments of a wireless communication apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
First, the basic concept of the present invention will be described. An object of the present invention is to realize high-efficiency transmission by positively using information on the allowable delay time on the communication partner side, that is, the number of times that retransmission is possible during packet transmission. Therefore, in the present invention, data is transmitted by a retransmission operation as shown in FIG. 1, for example. FIG. 1 is a diagram showing a basic concept of the present invention, and shows an operation example when retransmission can be performed three times within an allowable time. In conventional wireless communication devices, a target of, for example, PER (Packet Error Rate) = 1% is always set regardless of the allowable delay time (ie, without considering the number of retransmissions), and this value is achieved. The AMC set to be selected was selected and retransmitted.

  On the other hand, in the present invention, for example, in the case where three retransmissions are possible as in the example shown in FIG. 1, the first transmission and the second retransmission up to this are performed with the conventional AMC set. Transmission is performed at the same or higher rate (for example, AMC set achieving PER = 10%, which corresponds to AMC # 1 in the example of FIG. 1). As a result, the error rate (PER) increases as a result, but the occupation time of the line can be shortened as compared with the conventional case. If the error is not resolved even after two retransmissions and there is a packet that needs to be retransmitted a third time, a strict target value (eg, PER = 0.01%) is achieved so that reliable transmission is possible. AMC set to be transmitted (AMC # 2 in the example of FIG. 1) is selected and transmitted.

  FIG. 2 is a diagram illustrating a configuration example of the first embodiment of the communication system including the wireless communication device according to the present invention. This communication system includes a communication device A that is a data transmission source wireless communication device and a communication device B that is a data transmission destination wireless communication device, and the communication device A corresponds to the wireless communication device according to the present invention. .

  The communication device A includes a retransmission number prediction unit 1, an AMC set selection unit 2, a signal transmission unit 3, a signal reception unit 4, a channel quality measurement unit 5, a retransmission request detection unit 6, a memory unit 7, Is provided. The retransmission number prediction unit 1 predicts the number of retransmissions possible based on the quality information S2 and the retransmission packet information S10. The AMC set selection unit 2 selects an AMC set (a modulation scheme and a coding rate) based on the number of times of retransmission information S3 and the transmission path information S7. The signal transmission unit 3 encodes and modulates the transmission signal S1 taken out from the memory unit 7 and transmits it as a modulation signal S5. The signal receiving unit 4 demodulates the received high frequency received signal S6 and outputs the demodulation result as a received signal S9. Further, the signal receiving unit 4 extracts a pilot signal from the high frequency received signal S6 and outputs the extraction result to the line quality measuring unit 5 as a pilot signal S7. The line quality measuring unit 5 measures the line quality based on the pilot signal S7. As the channel quality, for example, a reception CINR (Carrier to Interference-plus-Noise Ratio) or a moving speed is used. The retransmission request detection unit 6 detects a retransmission request based on the demodulated received signal S9. The memory unit 7 stores the transmission signal S1 until the transmission is completed.

  The communication device B includes a signal reception unit 11, a memory unit 12, an error detection unit 13, a delay time management unit 14, and a signal transmission unit 15. The signal reception unit 11 demodulates the high frequency reception signal S11 and outputs the demodulation results as reception signals S12 and S14. The memory unit 12 stores the demodulated received signal S12. The error detector 13 detects a packet transmission error (including a case where the packet is lost) based on the demodulated received signal S12. When a packet transmission error is detected, the error detection unit 13 generates a retransmission request signal. The delay time management unit 14 manages the time of the demodulated signal stored in the memory unit 12. The signal transmission unit 15 modulates and transmits the transmission signal S17 and the retransmission request signal S15.

  Next, an operation in which the wireless communication device (communication device A) according to the present invention transmits a packet to the counterpart wireless communication device (communication device B) will be described. When the transmission signal S1 is generated in the communication device A, the transmission signal S1 is temporarily stored in the memory unit 7. Simultaneously with the generation of the transmission signal S1, the quality information S2 is notified to the retransmission number prediction unit 1 from a control unit (not shown). The quality information S2 includes the information amount of the signal S1, the allowable delay time, and the like. The retransmission number prediction unit 1 predicts how many retransmissions are possible based on information on the allowable delay time included in the signal S2 and the transmission capability of the system.

  The AMC set selection unit 2 selects an AMC set to be used at the time of transmission based on the retransmission number information S3 (prediction result of the retransmission number prediction unit 1) and the transmission path information S8 (line quality). Here, the operation in which the AMC set selection unit 2 selects the AMC will be described with reference to FIG. FIG. 3 is a flowchart showing an operation example in which the AMC set selection unit 2 selects an AMC set. When transmission (or retransmission) data is generated (step S31), the AMC set selection unit 2 confirms the retransmission number information S3 received from the retransmission number prediction unit 1. That is, it is confirmed whether or not the remaining number of transmissions is 1 (whether or not this time is the last transmission opportunity) (step S32). If it is determined in step S32 that the number of remaining transmissions is one (step S32, Yes), the AMC set selection unit 2 selects a target AMC set satisfying the target PER (target error rate) as T1 ( Step S33). On the other hand, when it is determined in step S32 that the remaining number of transmissions is not one (step S32, No), the AMC set selection unit 2 selects a target AMC set with T2 as the target PER (step S34). Then, the AMC set selection unit 2 notifies the signal transmission unit 3 of the modulation scheme / coding rate information S4 indicating the AMC set selected in step S33 or S34 (step S35).

  Here, in the present invention, T1 << T2. As a result, while there is a retransmission opportunity (even if an error occurs during retransmission, it can be retransmitted), the transmission rate is increased to reduce the occupied time of the line, and the last transmission opportunity is sufficient for reliable transmission A redundant transmission rate is adopted. If a sufficiently redundant transmission rate is used, the line occupancy time will increase, but since most of the data has been transmitted by the last transmission opportunity, the transmission rate is low only once at the end. Even if it is adopted, the total occupation time of the line can be expected to be significantly shortened. The signal transmission unit 3 encodes and modulates the transmission signal extracted from the memory unit 7 based on the modulation scheme / coding rate information S4 received from the AMC set selection unit 2, and obtains a modulation signal ( High-frequency transmission signal) S5 is transmitted.

  The high frequency transmission signal S5 transmitted by the communication device A is received by the communication device B as the high frequency reception signal S11. The signal reception unit 11 of the communication device B demodulates the high frequency reception signal S11 and outputs the demodulated reception signals S12 and S14 to the memory unit 12 and the error detection unit 13, respectively. The signal S12 is stored in the memory unit 12, and is sent to the upper layer as received data S13 when all the packets (or frames) are collected. Further, the time when the signal S12 is written in the memory unit 12 is notified to the delay time management unit 14 as memory management information S16, and may be variable during a specified time (depending on the quality information of the transmitted signal). Managed and maintained. Data for which all packets do not arrive within the specified time is discarded from the memory unit 12 after the specified time has elapsed.

  Based on the demodulated signal S14, the error detection unit 13 detects a packet in which an error has occurred on the transmission path or a loss has occurred for some reason in a series of signal sequences (packets). In order to transmit data to the upper layer as error-free data, it is necessary to retransmit a packet in which an error or loss has occurred and to receive all the series of signal sequences. Therefore, the error detection unit 13 generates a retransmission request signal S15 for notifying the communication device A of a packet for requesting retransmission when detecting a transmission error or loss of the packet. The signal transmission unit 15 encodes and modulates a signal obtained by adding the retransmission request signal S15 to the transmission signal S17 of the communication device B and transmits the signal to the communication device A.

  Further, in the communication device A, the signal receiving unit 4 demodulates the high frequency received signal S6 and outputs a received signal S9. The channel quality measuring unit 5 measures the channel quality using the pilot signal S7 received from the signal receiving unit 4, and outputs the measurement result to the AMC set selecting unit 2 as transmission path information S8. This transmission path information S8 is reference information when an AMC set is selected. When the demodulated reception signal S9 includes a retransmission request, the retransmission request detection unit 6 extracts the retransmission request, and sends the packet (frame) information indicated by the retransmission request to the retransmission number prediction unit 1 as retransmission packet information S10. Output. The retransmission number prediction unit 1 predicts the number of retransmissions that can be made in the same manner as in the first transmission. The AMC set selection unit 2 determines the AMC set at the time of retransmission according to the procedure shown in FIG. Then, the signal transmission unit 3 transmits (retransmits) a high-frequency transmission signal S5 obtained by performing coding and modulation using the AMC set determined by the AMC set selection unit 2 on the extracted signal.

  In the present embodiment, an example of operation in which the transmission rate is lowered only for the last transmission opportunity has been shown. However, the present invention is not limited to this, and transmission with redundancy at a plurality of transmission opportunities (for example, the last two transmissions). A rate may be selected. Further, the selectable target PERs (corresponding to T1 and T2 above) are not limited to two types, and the values thereof may take various values depending on the characteristics of the wireless communication apparatus. However, the condition of T1 <T2 is necessary (the target communication quality at the time of retransmission at or near the end needs to be set higher than in other cases).

  As described above, in the present embodiment, the number of retransmissions is estimated with reference to the allowable delay time of transmission information, and is high while there is a retransmission opportunity (when the estimated number of retransmissions is multiple). Transmission is performed using the encoding method and modulation method that become the transmission rate. On the other hand, when there is no retransmission opportunity, transmission is performed using the encoding method and modulation method that provides a sufficiently low transmission rate with redundancy. It was decided to do. Thereby, highly efficient and reliable data transmission can be realized.

Embodiment 2. FIG.
Next, the radio communication apparatus according to the second embodiment will be described. FIG. 4 is a diagram illustrating a configuration example of a second embodiment of a communication system including a wireless communication device according to the present invention. This communication system includes a communication device A that is a data transmission source wireless communication device and a communication device B that is a data transmission destination wireless communication device, and the communication device A corresponds to the wireless communication device according to the present invention. .

  The communication device A of the present embodiment includes an AMC set MIMO configuration selection unit 25 instead of the AMC set selection unit 2 of the communication device A of the first embodiment described above, and a modulation unit instead of the signal transmission unit 3 21 and a MIMO encoder 23, and a demodulator 22 and a MIMO decoder 25 in place of the signal receiver 4. Since the other parts are the same as those of the communication device A of the first embodiment, the same reference numerals are given and the description thereof is omitted.

  The modulation unit 21 encodes and modulates the transmission signal extracted from the memory unit 7 in accordance with the modulation scheme / coding rate information S4. The MIMO encoding unit 23 performs MIMO encoding (SDM: MIMO encoding by Space Division Multiplexing, STC: MIMO encoding by Space-Time Coding, etc.) of the modulated signal S21 based on the MIMO configuration information S23, and transmits each transmission antenna. The transmission information of is generated. The MIMO decoding unit 24 performs a MIMO decoding (signal separation) process on signals received by a plurality of antennas. The demodulator 22 performs demodulation and error correction of the MIMO-decoded signal S22. The AMC set MIMO configuration selection unit 25 selects an AMC set and a MIMO configuration at the time of transmission based on the number of times of retransmission information S3 and the transmission path information S8.

  In addition, the communication device B includes a MIMO decoding unit (MIMO Decoder) 26 and a demodulation unit 28 instead of the signal reception unit 11 of the communication device B of the first embodiment described above, and is replaced with a MIMO transmission unit instead of the signal transmission unit 15. An encoder (MIMO Encoder) 27 and a modulator 29 are provided. Since the other parts are the same as those of the communication device B of the first embodiment, the same reference numerals are given and description thereof is omitted.

  The MIMO decoding unit 26 performs a MIMO decoding process. The demodulator 28 performs demodulation and error correction processing on the MIMO-decoded signal S24. The MIMO encoding unit 27 performs MIMO encoding of the modulation signal S25. The modulation unit 29 encodes and modulates the transmission signal S17 and the retransmission request signal S15.

  Next, an operation in which the wireless communication device (communication device A) according to the present invention transmits a packet to the counterpart wireless communication device (communication device B) will be described. Basically, the same operation as in the first embodiment is performed, but in this embodiment, data is transmitted using MIMO using a plurality of antennas in addition to the AMC set. Here, the description will focus on the parts different from the operation of the first embodiment described above.

  The AMC set / MIMO configuration selection unit 25 selects an AMC set and a MIMO configuration to be used at the time of transmission based on the number of retransmission times information S3 and the transmission path information S8. For example, when using the two-stage target PER as in the first embodiment, the AMC set / MIMO configuration selection unit 25 selects the MIMO configuration that achieves PER = T2 and the AMC set of each channel when there is a retransmission opportunity. select. Specifically, when performing SDM-type MIMO transmission, the AMC set / MIMO configuration selection unit 25 uses which antenna among a plurality of antennas, what is the AMC set of a signal transmitted from each antenna, Such information is determined. Similarly, when performing orthogonal channel forming type MIMO transmission, the AMC set / MIMO configuration selecting unit 25 determines the number of simultaneous transmission channels, what is the AMC set of each channel, and the antenna weight for beam forming of each channel. Determine what information is. Similarly, when performing STC type MIMO transmission, the AMC set / MIMO configuration selection unit 25 determines information such as what matrix is used for STC encoding and what is the AMC set of each signal stream. On the other hand, when the transmission opportunity is the last one, the target PER = T1 is set, and the AMC set and the MIMO configuration are similarly selected.

  The modulation scheme and coding rate (AMC set) in the selection result are output to the modulation unit 21 as modulation scheme / coding rate information S4. Also, the MIMO configuration is output to the MIMO encoding unit 23 as MIMO configuration information S23.

  The modulation unit 21 performs transmission signal encoding and modulation processing based on the modulation scheme / coding rate information S4. When performing multiple-sequence simultaneous transmission by MIMO, the modulation unit 21 may divide a transmission signal into certain blocks and perform processing by applying different modulation schemes and coding rates. The MIMO encoding unit 23 performs MIMO encoding of the transmission signal based on the MIMO configuration information S23, and allocates to each antenna for transmission.

  Here, generally, SDM type and orthogonal channel forming type MIMO can dramatically increase the transmission capacity, so that a great effect can be obtained by shortening the line occupation time. On the other hand, since the diversity effect can be obtained by transmission / reception of STC, it is possible to obtain a greater degree of redundancy than a single antenna system. Therefore, using the characteristics of each scheme, for example, when there is an opportunity for retransmission, communication is performed at a high transmission rate by increasing the number of multiplexed SDMs. When there is no opportunity for retransmission, STC is used. By using the communication with redundancy due to the diversity effect, etc., data can be transmitted efficiently.

  The information transmitted by the communication device A is received by the communication device B through the transmission path. In communication apparatus B, first, MIMO decoding section 26 performs a MIMO decoding (signal separation) process to obtain reception information S24 after MIMO decoding. The demodulator 28 demodulates the decoded information S24 and accumulates it in the memory unit 12 until all the series of packets are completed. The error detection unit 13 performs the operation described in the first embodiment and generates retransmission request information S15. Modulator 29 encodes and modulates the signal obtained by adding retransmission request signal S15 to transmission signal S17, and outputs the result as signal S25. The MIMO encoding unit 27 transmits the signal S25 to the communication device A.

  Here, in order to realize transmission / reception of a MIMO signal, it is necessary to notify the MIMO configuration information from the transmission side to the reception side in advance. However, since this notification method is not related to the essence of the present invention, description thereof is omitted. Various methods are disclosed as a method of notifying the MIMO configuration information, and any one of them may be used.

  Further, in communication apparatus A, MIMO decoding unit 24 performs a MIMO decoding (signal separation) process on the received signal to obtain a MIMO-decoded signal S22. The demodulator 22 performs demodulation and error correction of the signal S22 after MIMO decoding, and obtains a received signal S9. The channel quality measurement unit 5 uses the pilot signal S7 received from the signal reception unit 4 to measure the channel quality of the MIMO transmission path, and outputs the measurement result to the AMC set / MIMO configuration selection unit 25 as transmission path information S8. . If retransmission request is included in received signal S9, retransmission request detection unit 6 extracts it, and outputs the packet (frame) information indicated by the retransmission request to retransmission number prediction unit 1 as retransmission packet information S10. The retransmission number prediction unit 1 predicts the number of retransmissions possible based on the retransmission packet information S10, and the AMC set / MIMO configuration selection unit 25 determines the AMC set and MIMO based on the prediction result (retransmission number information S3) and the transmission path information. Make configuration selections. Then, using this selection result (AMC set and MIMO configuration), modulation section 21 and MIMO encoding section 23 retransmit information.

  Thus, in the present embodiment, in a system that performs MIMO transmission, the number of retransmissions is estimated with reference to the allowable delay time of transmission information, and based on the estimation result, the modulation scheme, coding rate, and The MIMO configuration was selected and determined. Thereby, more efficient and reliable data transmission can be realized.

  As described above, the wireless communication apparatus according to the present invention is useful for a wireless communication system, and is particularly suitable for a wireless communication apparatus that transmits data using an adaptive modulation scheme.

It is a figure which shows the basic concept of this invention. It is a figure which shows the structural example of Embodiment 1 of the communication system containing the radio | wireless communication apparatus concerning this invention. It is a flowchart which shows the operation example in which an AMC set selection part selects an AMC set. It is a figure which shows the structural example of Embodiment 2 of the communication system containing the radio | wireless communication apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Retransmission number estimation part 2 AMC set selection part 3, 15 Signal transmission part 4, 11 Signal reception part 5 Channel quality measurement part 6 Retransmission request detection part 7, 12 Memory part 13 Error detection part 14 Delay time management part 21, 29 Modulation Unit 22, 28 Demodulator 23, 27 MIMO Encoder
24, 26 MIMO decoder (MIMO Decoder)
25 AMC Set / MIMO Configuration Selector

Claims (13)

When data is transmitted using the encoding method and modulation method selected and determined according to the transmission path state and a transmission error occurs, a transmission error occurs within the period allowed by the transmission destination device (retransmission allowable period). A wireless communication device that retransmits data (packets),
AMC set selection means for selecting an AMC set that is a combination of the encoding scheme and the modulation scheme based on the retransmission allowable period and the transmission path state when a transmission error occurs;
Retransmission means for retransmitting data having a transmission error using the AMC set selected by the AMC set selection means;
A wireless communication apparatus comprising: When multiple antennas are provided to transmit MIMO (Multiple-Input Multiple-Output) data,
The AMC set selection means, based on the retransmission allowable period and the transmission path state, MIMO configuration method (MIMO transmission scheme, MIMO multiplexing number) and MIMO- which is an AMC set when generating transmission signals from each antenna Select the AMC set,
2. The radio communication apparatus according to claim 1, wherein the retransmission section retransmits data having a transmission error using the MIMO configuration method and the MIMO-AMC set selected by the AMC set selection section.   The AMC set selection unit calculates the number of retransmission processes that can be executed within the retransmission allowable period based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), the calculation is performed. 3. The AMC set / the MIMO configuration method and the MIMO-AMC set are selected so that the transmission rate is lower than when the number of times exceeds n times. Wireless communication device.   The AMC set selection unit calculates the number of retransmission processes that can be executed within the retransmission allowable period based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), the calculation is performed. 3. The AMC set / the MIMO configuration method and the MIMO-AMC set are selected so as to satisfy a lower target error rate than when the number of performed times exceeds n times. A wireless communication device according to 1.   The wireless communication according to claim 3 or 4, wherein the AMC set selection means performs selection processing of the AMC set / the MIMO configuration method and the MIMO-AMC set with n = 1. apparatus.   The AMC set selection unit calculates the number of retransmission processes that can be executed within the retransmission allowable period based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), the calculation is performed. The radio communication apparatus according to claim 2, wherein MIMO transmission is performed by a SDM (Space Division Multiplexing) with a smaller number of multiplexing than when the number of times exceeds n times.   The AMC set selection means calculates the number of retransmission processes that can be executed within the retransmission allowable period based on the retransmission allowable period and the retransmission time, and when the calculated number is n or less (n: natural number), MIMO transmission by STC (Space-Time Coding) that provides a diversity effect is performed. On the other hand, when the calculated number exceeds n times, MIMO data transmission by SDM that can realize a high transmission rate is performed. The wireless communication apparatus according to claim 2. When data is transmitted using the encoding method and modulation method selected and determined according to the transmission path state and a transmission error occurs, a transmission error occurs within the period allowed by the transmission destination device (retransmission allowable period). A data transmission method for retransmitting data (packets),
An AMC set selection step of selecting an AMC set that is a combination of the encoding scheme and the modulation scheme based on the retransmission allowable period and the transmission path state when a transmission error occurs;
A retransmission data generation step of generating retransmission data by encoding and modulating data having a transmission error using the AMC set selected in the AMC set selection step;
A data transmission method comprising: When performing multiple-input multiple-output (MIMO) transmission of data using multiple antennas,
In the AMC set selection step, based on the retransmission allowable period and the transmission path state, a MIMO configuration method (MIMO transmission method, number of multiplexed MIMO) and a MIMO- that is an AMC set for generating a transmission signal from each antenna Select the AMC set,
9. The data transmission method according to claim 8, wherein in the retransmission data generation step, retransmission data is generated using the MIMO configuration method and the MIMO-AMC set selected in the AMC set selection step.   In the AMC set selection step, the number of retransmission processes that can be executed within the retransmission allowable period is calculated based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), the calculation is performed. 10. The AMC set / the MIMO configuration method and the MIMO-AMC set are selected so that the transmission rate is lower than when the number of times exceeds n times. Data transmission method.   In the AMC set selection step, the number of retransmission processes that can be executed within the retransmission allowable period is calculated based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), the calculation is performed. 10. The AMC set / the MIMO configuration method and the MIMO-AMC set are selected so as to satisfy a lower target error rate than when the number of performed times exceeds n times. The data transmission method described.   In the AMC set selection step, the number of retransmission processes that can be executed within the retransmission allowable period is calculated based on the retransmission allowable period and the retransmission time, and when the calculated number is n or less (n: natural number) The data transmission method according to claim 9, wherein MIMO transmission is performed by SDM (Space Division Multiplexing) with a smaller number of multiplexing than when the calculated number exceeds n times.   In the AMC set selection step, the number of retransmission processes that can be executed within the retransmission allowable period is calculated based on the retransmission allowable period and the retransmission time. If the calculated number is n or less (n: natural number), transmission is performed. It is characterized by performing MIMO transmission by STC (Space-Time Coding) that can achieve a diversity effect, while performing transmission by SDM that can realize a high transmission rate when the calculated number exceeds n times. The data transmission method according to claim 9.

Images