JP5864184B2 - Communications system - Google Patents

Description

  The present invention relates to a communication device, a communication system, and a communication control method.

  Conventionally, in a LTE / WiMAX / XGP system or the like, a packet combining type retransmission control (H-ARQ) method is used, and whether there is a need for retransmission is determined by checking whether there is an error in received data at the receiving side device. Judgment is made based on (Cyclic Redundancy Check), and only when there is a data error, the receiving side apparatus performs retransmission control for requesting the transmitting side apparatus to retransmit data. Also, in the packet combining type H-ARQ scheme, data that has been erroneous in the receiving apparatus is stored, and signal combining is performed at the physical layer level with the data that will be retransmitted later from the transmitting apparatus. A process of reducing data errors is performed (for example, Patent Document 1).

JP 2008-72662 A

  In the conventional packet synthesis type retransmission control process, the result of determining whether there is an error in the received data on the receiving device side is a binary value of “no error (ACK)” or “with error (NACK)” (for example, ACK The information is transmitted from the receiving apparatus to the transmitting apparatus at “1” in the case of “1” and “0” in the case of NACK). At this time, if packet-synthesizing retransmission control is being performed, whether or not a small amount of power was sufficient to successfully demodulate the data received at the first time at the receiving side device, or a large amount of power was sufficient It is desirable to change and optimize the retransmission data transmission control scheme (for example, transmission power, modulation scheme, etc.) in the transmission-side apparatus depending on whether or not there is any.

  For example, a transmission error occurs in the receiving device that transmits the first packet (hereinafter referred to as “initial transmission data”) from the transmission device and receives the initial transmission data. Suppose that the packet (hereinafter referred to as “retransmission data”) is retransmitted, and then the reception side apparatus combines the initial transmission data and the retransmission data and succeeds in receiving the packet data.

  At this time, if there is a relationship such as the initial transmission data, the retransmission data, and the received channel quality (SINR) shown in FIG. 8, the first transmission data transmitted first by the transmission side device is the data after demodulation of the reception side device. Is slightly less than the required line quality, so the reception process fails. When the reception side apparatus fails in the reception process, the transmission side apparatus retransmits equivalent data with the same transmission power as the initial transmission data. Since the data transmitted from the transmitting device is transmitted to the receiving device through the same propagation path as the initial transmission, the receiving line quality (SINR) on the receiving side becomes the same value as the first time, and the receiving side device The received line quality obtained by combining the initial transmission data and the retransmitted data with a packet greatly exceeds the required line quality.

  Therefore, when a certain communication is communicating with a quality that exceeds the required line quality (excessive transmission power), it causes a large interference to other devices, resulting in a decrease in sector throughput and an average delay. It can be a factor that degrades system efficiency, such as an increase in time and a decrease in system capacity.

  In general, it is desirable to reduce the power consumption of the transmission side device. In particular, when the transmission side device is a mobile station such as a mobile phone terminal, the transmission power should be minimized from the viewpoint of battery capacity. Is desirable.

  Therefore, an object of the present invention made in view of the above problems is to provide a communication device, a communication system, and a communication control method capable of dynamically controlling retransmission request information and improving system efficiency. There is.

The communication system according to the present invention includes:
A communication system comprising a first communication device and a second communication device,
The first communication device is
A first transceiver for transmitting data to the second communication device and receiving retransmission request information of the data from the second communication device;
A first control unit that controls retransmission data to be transmitted to the second communication device based on the retransmission request information when the first transmission / reception unit receives the retransmission request information;
With
The second communication device is
A second transmitter / receiver for receiving the data from the first communication device and transmitting retransmission request information for requesting retransmission of the data;
A second controller that detects an error in the data received by the second transmitter / receiver and generates the retransmission request information when there is an error;
With
When generating the retransmission request information, the second control unit calculates a variance value based on information received in the past and the data on which an error has been detected, and the bits of the retransmission request information based on the variance value In addition to controlling the length, the information obtained from the received channel quality of the data received in the past and the received channel quality when the data error is detected are included in the retransmission request information,
When receiving the retransmission request information, the first control unit of the first communication device uses transmission power for retransmitting the data from a prescribed transmission power according to a received channel quality value of the retransmission request information. Also, it is characterized by determining a low transmission power.

The communication system according to the present invention includes:
The first control unit controls the transmission power value to be smaller as the received channel quality value of the retransmission request information exceeds a predetermined threshold and the received channel quality is higher.

  According to the communication device, the communication system, and the communication control method of the present invention, it is possible to dynamically control retransmission request information and improve system efficiency.

1 is a block diagram of a communication system according to a first embodiment. 3 is a flowchart illustrating an operation of the communication system according to the first embodiment. 4 is a table showing a relationship between a dispersion value of a received channel quality value and the number of bits of retransmission request information in the communication system of the first embodiment. 3 is a table showing a relationship between a received channel quality value and a transmission power value in the communication system according to the first embodiment. 3 is a conceptual diagram of transmission power at the time of retransmission in the communication system according to Embodiment 1. FIG. 6 is a block diagram of a communication system according to Embodiment 2. FIG. 6 is a flowchart illustrating an operation of the communication system according to the second embodiment. It is a conceptual diagram of transmission power at the time of retransmission in the conventional example.

  Embodiments of the present invention will be described below.

(Embodiment 1)
FIG. 1 is a block diagram of a communication system according to Embodiment 1 of the present invention. The communication system according to Embodiment 1 of the present invention includes a first communication device 1 and a second communication device 2. The first communication device 1 is preferably a mobile station or a base station, and the second communication device 2 is preferably a base station when the first communication device 1 is a mobile station, and the first communication device 1 is a base station. In the case of a station, it is a mobile station.

  The first communication device 1 includes a control unit 11, a transmission / reception unit 12, and an antenna 13. The control unit 11 includes a transmission baseband processing unit 111, a retransmission control unit 114, a transmission power control unit 115, and a reception baseband processing unit 116. The transmission baseband processing unit 111 includes an error correction processing unit 112 and a transmission power processing unit 113. The transmission / reception unit 12 includes a transmission RF processing unit 121 and a reception RF processing unit 122.

  The error correction processing unit 112 performs error correction processing on data transmitted from the first communication device 1 to the second communication device 2. The error correction processing unit 112 performs error correction processing on retransmission data based on retransmission request information in response to a request from the retransmission control unit 114. Then, the error correction processing unit 112 outputs the data subjected to the error correction processing (retransmission data) to the transmission power processing unit 113.

  The transmission power processing unit 113 performs transmission power control of data that has been subjected to error correction processing. Further, the transmission power processing unit 113 performs transmission power control on retransmission data based on the transmission power determined by the transmission power control unit 115 based on the retransmission request information regarding the retransmission data. Specifically, the transmission power processing unit 113 notifies the transmission RF processing unit 121 of the transmission power determined by the transmission power control unit 115.

  When retransmission request information is converted into a baseband signal in reception baseband processing section 116, retransmission control section 114 requests error correction processing section 112 for retransmission data based on the retransmission request information.

  The transmission power control unit 115 determines transmission power based on the retransmission request information converted into the baseband signal. Then, the transmission power control unit 115 notifies the transmission power processing unit 113 of the determined transmission power.

  The reception baseband processing unit 116 converts the retransmission request information received by the transmission / reception unit 12 into a baseband signal, and converts various data received by the transmission / reception unit 12 into a baseband signal. Reception baseband processing section 116 outputs retransmission request information converted into a baseband signal to retransmission control section 114 and transmission power control section 115.

  The transmission RF processing unit 121 converts data to be transmitted into an RF signal. Then, the transmission / reception unit 12 transmits the converted data to the second communication device 2 through the antenna 13 based on the transmission power notified from the transmission power processing unit 113. The transmission RF processing unit 121 converts the retransmission data into an RF signal. The transmission / reception unit 12 transmits the converted retransmission data to the second communication device 2 via the antenna 13.

  The reception RF processing unit 122 decodes the retransmission request information converted into the RF signal. Then, reception RF processing section 122 outputs the decoded retransmission request information to reception baseband processing section 116. The retransmission request information is received from the second communication device 2 by the transmission / reception unit 12 via the antenna 13.

  The second communication device 2 includes an antenna 21, a transmission / reception unit 22, and a control unit 23. The transmission / reception unit 22 includes a reception RF processing unit 221 and a transmission RF processing unit 222. The control unit 23 includes a reception baseband processing unit 231, a reception channel quality value calculation unit 232, a reception channel quality value variance calculation unit 233, an error determination unit 234, a retransmission request information generation unit 235, and a transmission baseband process. Part 236.

  The reception RF processing unit 221 decodes the data converted into the RF signal. The transmission / reception unit 22 receives the data from the first communication device 1 via the antenna 21. Then, the reception RF processing unit 221 outputs the decoded data to the reception baseband processing unit 231.

  The transmission RF processing unit 222 converts the retransmission request information passed from the transmission baseband processing unit 236 into an RF signal. Then, the transmission / reception unit 22 transmits the retransmission request information converted into the RF signal to the first communication device 1 via the antenna 21.

  The reception baseband processing unit 231 converts the data decoded by the reception RF processing unit 221 into a baseband signal. Reception baseband processing section 231 then outputs the converted baseband signal to reception channel quality value calculation section 232 and error determination section 234.

  The reception line quality value calculation unit 232 calculates the reception line quality value of the data received from the first communication device 1 based on the baseband signal passed from the reception baseband processing unit 231. For example, the received channel quality value is represented by SINR (Signal to Interference and Noise Power Ratio) or received signal strength. Also, the received channel quality value calculation unit 232 outputs the calculated received channel quality value to the received channel quality value variance calculation unit 233 and the retransmission request information generation unit 235.

  The received channel quality value variance calculating unit 233 calculates a variance value of the received channel quality value of the data received from the first communication device 1 based on the received channel quality value passed from the received channel quality value calculating unit 232. In order to calculate the variance, the received channel quality value variance calculating unit 233 uses the received channel quality value of the data calculated in the past in addition to the received channel quality value passed from the received channel quality value calculating unit 232. Received line quality values of data calculated in the past are stored in a memory or the like (not shown). Then, the received channel quality value variance calculation unit 233 outputs the calculated variance value to the retransmission request information generation unit 235.

  The error determination unit 234 determines whether there is an error in the data received from the first communication apparatus 1 based on the baseband signal passed from the reception baseband processing unit 231. Then, the error determination unit 234 notifies the retransmission request information generation unit 235 of whether there is an error in the data received from the first communication device 1.

  The retransmission request information generation unit 235 generates retransmission request information for the data determined to have an error by the error determination unit 234. The retransmission request information generation unit 235 determines the bit value of the retransmission request information based on the received channel quality variance value passed from the received channel quality value variance calculation unit 233. The retransmission request information includes the received channel quality value calculated by the received channel quality value calculator 232 in order to determine the transmission power when the first communication device 1 transmits the retransmission data. Then, retransmission request information generation section 235 outputs the generated retransmission request information to transmission baseband processing section 236.

  The transmission baseband processing unit 236 performs baseband processing on the retransmission request information generated by the retransmission request information generation unit 235, and outputs the baseband processed data to the transmission RF processing unit 222.

  Next, the operation of the communication system according to Embodiment 1 will be described with reference to the flowchart shown in FIG.

  First, the error correction processing unit 112 of the first communication device 1 performs error correction processing on the data to be transmitted (step S1). Next, the transmission power processing unit 113 performs transmission power control on the data that has been subjected to error correction processing (step S2).

  Subsequently, the transmission RF processing unit 121 converts the data subjected to transmission power control into an RF signal (step S3). And the transmission / reception part 12 transmits the data converted into RF signal from the antenna 13 to the 2nd communication apparatus 2 (step S4).

  Next, the transmission / reception unit 22 of the second communication device 2 receives the data transmitted from the first communication device 1 via the antenna 21 (step S5). Subsequently, the reception RF processing unit 221 decodes the data converted into the RF signal, and then the reception baseband processing unit 231 converts the decoded data into a baseband signal (step S6).

  Subsequently, the reception channel quality value calculation unit 232 calculates the reception channel quality value of the data converted into the baseband signal. The reception channel quality value variance calculation unit 233 calculates the variance of the reception channel quality value of the data converted into the baseband signal (step S7). In order to calculate the variance, the received channel quality value variance calculating unit 233 uses the received channel quality value of the data calculated in the past.

  Subsequently, the error determination unit 234 determines whether there is an error in the received data (step S8). If the error determination unit 234 determines that there is an error, the process proceeds to step S9. If it is determined that there is no error, the process is completed.

  If the error determination unit 234 determines that there is an error, the retransmission request information generation unit 235 generates retransmission request information based on the received channel quality value and the distribution of the received channel quality value (step S9). Specifically, retransmission request information generation section 235 includes the received line quality value in retransmission request information. Also, retransmission request information generation section 235 controls (determines) the number of bits of retransmission request information according to the table shown in FIG. 3, for example, based on the received channel quality variance value.

The table of FIG. 3 shows the variance value of the received channel quality value and the number of bits of retransmission request information. Here, the _{V a} is a dispersion value, the magnitude relation between _{V b} and _{V c,} a _{V a <V b <V c} , also the A, and B, the magnitude relation between the C, A < B <C. When the variance of the received channel quality value is large, it means that the characteristic variation of the propagation path in communication is large. In this case, retransmission request information generation section 235 increases the number of bits allocated for retransmission request information so that it can accurately follow changes in propagation path characteristics and minimize characteristic deterioration. Take control. On the other hand, when the variance of the received channel quality is small, control is performed so as to reduce the number of bits allocated for retransmission request information of a plurality of bits that are dynamically changed to reduce the overhead of control information. It should be noted that the larger the number of bits allocated for retransmission request information, the more accurate the retransmission request information can be expressed and the wider the dynamic range.

  Subsequently, the transmission baseband processing unit 236 performs baseband processing of the retransmission request information, and the transmission RF processing unit 222 converts the retransmission request information into an RF signal. And the transmission / reception part 22 transmits the resending request information converted into RF signal to the 1st communication apparatus 1 via the antenna 21 (step S10).

  Subsequently, the transmission / reception unit 12 of the first communication device 1 receives the retransmission request information via the antenna 13 (step S11). Then, the reception RF processing unit 122 of the first communication device 1 decodes the retransmission request information converted into the RF signal, and the reception baseband processing unit 116 converts it into a baseband signal (step S12).

  Subsequently, when retransmission request information is converted into a baseband signal in reception baseband processing section 116, retransmission control section 114 requests error correction processing section 112 for retransmission data based on the retransmission request information. Then, in response to the request from the retransmission control unit 114, the error correction processing unit 112 performs error correction processing on retransmission data based on the retransmission request information (step S13).

  Also, the transmission power control unit 115 determines the transmission power based on the retransmission request information converted into the baseband signal, for example, according to the table shown in FIG.

The table in FIG. 4 shows the relationship between the received channel quality value and the transmission power value. Here, the magnitude relationship between x _1, x _{2, and} x ₃ that are received channel quality values is x ₁ <x ₂ <x ₃ . Further, based on the threshold value x ₀ to a predetermined relates received channel quality values, _{x 1} is less than _{x 0, x 2} and _{x 3} is assumed to exceed _{x 0.}

As shown in FIG. 4, when the received channel quality value is x ₁ , that is, less than x ₀ , the transmission power control unit 115 determines the transmission power as Y, which is a prescribed transmission power value.

On the other hand, when the received channel quality value exceeds x ₂ or x ₃ , that is, x ₀ , the transmission power control unit 115 determines the transmission power to a value lower than Y that is the prescribed transmission power. As shown in FIG. 4 in particular, the reception channel quality value if _{x 2,} the transmission power value is set to Y- _(x 2 -x _0). When the received channel quality value is x ₃ , the transmission power value is set to Y− (x ₃ −x ₀ ). That is, the transmission power control unit 115 exceeds a predetermined threshold value x ₀ and higher line-ray quality value is controlled so as to reduce the transmission power value.

  Then, the transmission power control unit 115 performs transmission power control on the retransmission data based on the transmission power determined by the retransmission request information (step S14). Subsequently, the transmission RF processing unit 121 converts the retransmission data into an RF signal (step S15), and the transmission / reception unit 12 transmits the retransmission data to the second communication device 2 via the antenna 13 (step S16). Then, the transmission / reception unit 22 of the second communication device 2 receives the retransmission data (step S17), and the process ends.

  FIG. 5 is a conceptual diagram of transmission power at the time of retransmission according to the present invention. As shown in FIG. 5, when the initial transmission data is less than the required channel quality, the transmission power at the time of retransmission can be made lower than the transmission power for transmitting the initial transmission data to minimize the transmission power. It becomes possible.

  As described above, according to the present invention, the second communication device 2 increases or decreases the number of bits of the retransmission request information according to the dispersion value of the received channel quality value of the data transmitted from the first communication device 1. Information can be dynamically controlled to improve system efficiency, such as increasing sector throughput, reducing average delay time, increasing system capacity, and reducing power consumption.

  In addition, in the retransmission control method of the first communication device 1 which is a transmission side device, an incremental redundancy method (a method of changing the puncture pattern of the error correction processing unit 112 at the time of initial transmission / retransmission when retransmission data is generated) is adopted. If the retransmission process is performed a plurality of times, the puncture pattern at the time of retransmission is preferentially selected from the puncture pattern of the data having the low “reception line quality value” represented by the variable bit number. The error rate characteristics may be improved by using

  In step S9, the reception channel quality value calculation unit 232 controls based on FIG. 3 such that the larger the variance of the reception channel quality value, the larger the number of bits allocated for retransmission request information. In addition, control may be performed such that the smaller the variance of the received channel quality value, the larger the number of bits allocated for retransmission request information. When the reception line quality value is small and the reception line quality is stable, there are fewer data errors. By controlling in this way, a larger number of bits can be obtained in an environment with less data errors. By transmitting retransmission request information, the allocated bits can be used more effectively.

(Embodiment 2)
The second embodiment of the present invention will be described below. FIG. 6 is a block diagram showing a configuration of a communication system according to Embodiment 2 of the present invention. The same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. Compared with the configuration according to the first embodiment, the communication system according to the second embodiment includes a likelihood information calculation unit 237 instead of the reception channel quality value calculation unit 232, and also includes a reception channel quality value variance calculation unit. The difference is that a likelihood information variance calculating unit 238 is provided instead of 233.

  The likelihood information calculation unit 237 calculates likelihood information of data received from the first communication device 1. Likelihood information is information that represents the likelihood of received data, and is information that can be calculated at a stage prior to demodulation by the reception baseband processing unit 231. The likelihood information variance calculation unit 238 calculates the variance value of the likelihood information of the data received from the first communication device 1. In order to calculate the variance, the likelihood information variance calculation unit 238 uses the likelihood information of the data calculated in the past. The likelihood information of data calculated in the past is stored in a memory or the like (not shown).

  Next, the operation of the communication system according to Embodiment 2 will be described with reference to the flowchart shown in FIG. The same operations as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Compared with the operation of the communication system according to the first embodiment, the operation of the communication system according to the second embodiment includes a step of calculating likelihood information and variance in step S27 instead of step S7. Further, a difference is that, instead of step S9, a step of generating retransmission request information based on likelihood information and variance of likelihood information is provided in step S29.

  In step S <b> 27, the likelihood information calculation unit 237 calculates likelihood information of data received from the first communication device 1. Further, the likelihood information variance calculation unit 238 calculates the variance of the likelihood information of the data received from the first communication device 1. In order to calculate the variance, the likelihood information variance calculation unit 238 uses the likelihood information of the data calculated in the past.

  In step S29, when the error determination unit 234 determines that there is an error, the retransmission request information generation unit 235 generates retransmission request information based on the likelihood information and the variance of the likelihood information. Specifically, retransmission request information generation section 235 generates retransmission request information so as to increase the number of bits of retransmission request information as the variance of likelihood information increases, based on the variance of likelihood information.

  As described above, according to the communication system according to the second embodiment, the second communication apparatus 2 determines the received line quality value of the data transmitted from the first communication apparatus 1 based on the likelihood information instead of the received line quality value. Since the number of bits of retransmission request information is increased or decreased according to the variance value, retransmission request information can be dynamically controlled to improve system efficiency such as sector throughput, delay time, system capacity, and power consumption reduction.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

1 first communication device 11 control unit 111 transmission baseband processing unit 112 error correction processing unit 113 transmission power processing unit 114 retransmission control unit 115 transmission power control unit 116 reception baseband processing unit 12 transmission / reception unit 121 transmission RF processing unit 122 reception RF Processing unit 13 Antenna 2 Second communication device 21 Antenna 22 Transmission / reception unit 221 Reception RF processing unit 222 Transmission RF processing unit 23 Control unit 231 Reception baseband processing unit 232 Reception channel quality value calculation unit 233 Reception channel quality value variance calculation unit 234 Error Determination unit 235 Retransmission request information generation unit 236 Transmission baseband processing unit 237 Likelihood information calculation unit 238 Likelihood information variance calculation unit

Claims (2)

A communication system comprising a first communication device and a second communication device,
The first communication device is
A first transceiver for transmitting data to the second communication device and receiving retransmission request information of the data from the second communication device;
A first control unit that controls retransmission data to be transmitted to the second communication device based on the retransmission request information when the first transmission / reception unit receives the retransmission request information;
With
The second communication device is
A second transmitter / receiver for receiving the data from the first communication device and transmitting retransmission request information for requesting retransmission of the data;
A second controller that detects an error in the data received by the second transmitter / receiver and generates the retransmission request information when there is an error;
With
When generating the retransmission request information, the second control unit calculates a variance value based on information received in the past and the data on which an error has been detected, and the bits of the retransmission request information based on the variance value In addition to controlling the length, the information obtained from the received channel quality of the data received in the past and the received channel quality when the data error is detected are included in the retransmission request information,
When receiving the retransmission request information, the first control unit of the first communication device uses transmission power for retransmitting the data from a prescribed transmission power according to a received channel quality value of the retransmission request information. A communication system characterized by determining a low transmission power. 2. The communication system according to claim 1 , wherein the first control unit controls the transmission power value to be smaller as the received channel quality value of the retransmission request information exceeds a predetermined threshold and the received channel quality is higher. .

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