JP2008166867A - Communication equipment and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve communication efficiency with a communicating party for which response time is not stipulated. <P>SOLUTION: The communication equipment capable of adaptively switching a modulation system and requesting it to the communicating party is equipped with: a modulation system comparison part 126 for performing the matching comparison of the modulation system requested to the communicating party and the modulation system of data received from the communicating party; and a response time estimation part 127 for estimating the time from the request of the modulation system to the communicating party to the reception of the data of the requested modulation system as the response time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for improving communication efficiency.

  As a technique for improving communication efficiency, a technique (adaptive modulation system) that adaptively switches a modulation system according to communication quality is known. The most suitable modulation method for communication is to measure the communication quality of received frames (for example, SINR (signal to noise / interference power ratio), EVM (error vector magnitude)), and the modulation method with the maximum modulation efficiency with a low error rate. Is determined by notifying the communication partner (see, for example, Patent Document 1). In general, the higher the modulation efficiency, the higher the required S / N. For example, considering the level of 1% FER (frame error rate), the S / N required to communicate BPSK may be about 10 dB. However, since the amount of information per symbol is only 1 bit, the throughput is slow. On the contrary, in 64QAM and the like, the amount of information per symbol is 6 bits, so the throughput is high, but a good communication quality is required because an S / N of about 26 dB is required.

In addition, a technique for controlling transmission power is known for stabilization of SDMA (space division multiple access) communication and multilevel stabilization with a strong electric field (not deteriorating the outer symbols of the QAM system). The optimum transmission power is determined by notifying or instructing the communication partner of the power to be changed during communication.
JP 2005-244858 A

  When controlling the modulation method and transmission power, after the control command is issued, the modulation method and transmission power are switched after waiting for a response from the communication partner. When the response time from the communication partner is specified in advance, the switching operation may be performed after the specified response time has elapsed, but when the response time is not specified, an error occurs if the switching timing is incorrect, There is a problem in that retransmission processing is required and communication efficiency is reduced.

  The present invention relates to a communication apparatus capable of adaptively switching a modulation method and requesting a communication partner, a means for performing a coincidence comparison between the modulation method requested of the communication partner and the modulation method of data received from the communication partner, and a communication partner Means for detecting the time from when the modulation scheme is requested to when the requested modulation scheme data is received. In addition, the present invention performs a coincidence comparison between the modulation method requested from the communication partner and the modulation method of the data received from the communication partner until the data of the requested modulation method is received after the modulation method is requested from the communication partner. Is estimated as the response time of the communication partner.

  According to the above configuration, by estimating the time until the data of the modulation method requested from the communication partner is received as the response time of the communication partner, even when communicating with a communication partner whose response time is not specified, it is estimated. Based on the response time, the modulation scheme and transmission power can be switched at an appropriate timing, so that retransmission processing can be avoided and communication efficiency can be improved.

  FIG. 1 is a diagram showing a configuration of a communication apparatus according to the present invention. The communication device 100 includes an amplification unit 110, a physical layer unit 120, and an upper layer unit 130. The amplifying unit 110 amplifies a signal received via an antenna with an LNA (low noise amplifier), converts the radio frequency (RF) to an intermediate frequency (IF), converts it to a digital signal, and further converts it to an IQ signal. To the physical layer unit 120.

  The physical layer unit 120 demodulates by performing timing synchronization and frequency synchronization of the IQ signal, calculates a communication quality index (EVM or SINR), and then decodes, and a storage unit that stores the received modulation scheme 122, a calculation unit 123 that calculates a frame error of the decoded signal, a determination unit 124 that determines a requested modulation method based on a communication quality index and sends it to the upper layer unit 130, and a memory that stores the requested modulation method A comparison unit 126 that compares the received modulation method with the requested modulation method, and an estimation unit 127 that estimates a response time based on the comparison result. Further, a frame forming unit 128 that forms a physical layer frame of transmission data modulated by the modulation method determined based on the communication quality index or the modulation method determined by the upper layer unit 130, and the data of the formed frame is encoded and modulated And a modulation / coding unit 129.

  The upper layer unit 130 includes a reception unit 131 that receives data from the physical layer unit 120, a transmission unit 132 that acquires transmission data from a communication partner, and a modulation scheme determination unit 133 that determines a modulation scheme of transmission data. . Information indicating the determined modulation method and transmission data are supplied to the physical layer unit 120.

  FIG. 2 is a diagram showing a frame configuration of data formed by the physical layer frame forming unit 128 of the physical layer unit 120. The frame is divided into a fixed modulation unit and an adaptive modulation unit, and transmission data transmitted from the higher layer unit 130 and a modulation scheme request for requesting a modulation scheme from a communication partner are inserted into the adaptive modulation unit. The fixed modulation unit uses a modulation method with good communication quality such as π / 2DBPSK, for example, and transmits information indicating a training symbol for synchronization and a modulation method inserted in the adaptive modulation unit.

  3 to 5 are diagrams showing the flow of response time estimation operation executed by the response time estimation unit 127 of the physical layer unit 120. In FIG. 3, the modulation scheme received in step S101 is compared with the requested modulation scheme. When the received modulation method matches the requested modulation method (S101: Yes), the estimated response time is assumed to be the time from requesting the modulation method to receiving data reflecting the modulation request (S102). , S101 to S102 are repeated a predetermined number of times. If the received modulation scheme does not match the requested modulation scheme (S101: No), it is assumed that estimation is impossible, and S101 to S102 are repeated a predetermined number of times.

  FIG. 4 shows the estimated time. First, it is checked whether the requested modulation method has changed from the previous frame (S201). If it has changed (S202: Yes), the received modulation method and the requested modulation are checked. The method is compared (S203), and if the received modulation method matches the requested modulation method (S203: Yes), the response time is estimated. FIG. 5 further includes a process (S204) for comparing the modulation scheme requested in the previous frame with the modulation scheme received in the previous frame.

  FIG. 6 shows the flow of modulation control based on the estimated response time. If the estimated response time has elapsed since the modulation request was issued (S301: Yes), it is confirmed whether a continuous error has occurred (S302). If a continuous error has occurred (S302: Yes) Then, a modulation scheme lower than the modulation scheme is selected by transmitting in the previous frame (S303).

  When the estimated response time has passed since the modulation request was issued, it is possible to switch the modulation method at an appropriate timing by confirming the occurrence of a continuous error and setting the subsequent modulation method. Also in the transmission power control, the transmission power can be switched at an appropriate timing based on the estimated response time.

  According to the above embodiment, even when communicating with a communication partner whose response time is not defined by estimating the time until receiving the data of the modulation method requested from the communication partner as the response time of the communication partner. Since it is possible to switch the modulation scheme and transmission power at an appropriate timing based on the response time, retransmission processing can be avoided and communication efficiency can be improved.

The figure which shows the structure of the communication apparatus of this invention The figure which shows the structure of the flame | frame which a communication apparatus forms Diagram showing the flow of response time estimation operation Diagram showing the flow of response time estimation operation Diagram showing the flow of response time estimation operation Diagram showing the flow of modulation control

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Communication apparatus 110 Amplification part 120 Physical layer part 121 Demodulation decoding part 122 Memory | storage part 123 Operation part 124 Judgment part 125 Memory | storage part 126 Comparison part 127 Estimation part 128 Frame formation part 129 Modulation encoding part 130 Upper layer part 131 Reception part 132 Transmission part 133 Modulation method determination unit

Claims (4)

In a communication device that can adaptively switch the modulation method and request the communication partner,
Means for performing a comparison between the modulation method requested of the communication partner and the modulation method of data received from the communication partner;
A communication device comprising means for detecting a time from requesting a modulation method to a communication partner until receiving data of the requested modulation method.   The communication apparatus according to claim 1, further comprising means for performing modulation control switching control for the communication partner on the basis of a time from requesting the modulation method to the communication partner until receiving data of the requested modulation method.   The communication apparatus according to claim 1, further comprising means for performing transmission power switching control for the communication partner based on a time from requesting the modulation method to the communication partner until receiving data of the requested modulation method.   The comparison between the modulation method requested from the communication partner and the modulation method of the data received from the communication partner is performed, and the time from requesting the modulation method to the communication partner until receiving the data of the requested modulation method is determined. A communication method that estimates response time.

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