JP2007067817A - Receiver and receiving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent deterioration in ARQ performance even if the quality of radio line is deteriorated. <P>SOLUTION: In a channel estimation value calculation unit 103, a phase variation amount for each symbol is calculated from a PL symbol despread by the PL despread unit 102, and its expected value so that the phase variation amounts of the two or more symbols are averaged and defined as a channel estimation value. A first synchronization detection unit 104 compensates the phase for the PL receive symbol with the channel estimation value. An error bit detection unit 105 counts the number of error symbols of the PL receive symbol. A weight factor determination unit 106 determines a weight factor based on the small and large relation with threshold value and the number of error symbols. A second synchronization detection unit 108 compensates the phase for the data receive packet with the channel estimation value. A data buffer unit 109 stores the data receive packet in which the weight factor is multiplied, and a data synchronization unit 110 synchronizes the receive packet received this time, and the receive packet received previously and stored in the data buffer unit 109. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a receiving apparatus or the like of a wireless communication system that transmits high-speed packets, and more particularly to a receiving apparatus and a receiving method used in a wireless communication system to which ARQ (Automatic Repeat Request) is applied.

2. Description of the Related Art Conventionally, in wireless communication systems that perform high-speed packet transmission, in order to improve data reception performance for decoded data that is synchronously detected using a phase change amount of a known symbol (hereinafter referred to as PL (Pilot) symbol). ARQ is used. This ARQ is a method of automatically performing a process of retransmitting a data unit (frame) in which an error is detected on the receiving side. In other words, ARQ is a packet transmission method in which a series of data is divided into small blocks and transmitted, and when an error occurs during communication on the receiving side, only a faulty block is automatically retransmitted. As for a wireless communication system using ARQ, a system is disclosed in which a receiving side combines an already received packet and a retransmitted packet and performs error correction processing on the combined packet (for example, a patent). Reference 1).
JP 2004-104293 A

  However, in the conventional ARQ system, the receiving side performs error correction processing by synthesizing all retransmission packets, so that the propagation environment on the radio line is deteriorated and communication is congested at the time of retransmission. If the quality of the retransmitted packet deteriorates in such a state, the quality of the combined packet also deteriorates, and as a result, the ARQ performance may deteriorate. Therefore, even if ARQ is used, it may not be possible to improve data reception performance.

  The present invention has been made in view of the above points, and prevents degradation of ARQ performance even if the quality of the radio channel deteriorates during processing in which the transmission side retransmits a frame in which an error is detected on the reception side. An object of the present invention is to provide a receiving apparatus and a receiving method capable of performing the above.

  The receiving apparatus of the present invention is a receiving apparatus used in a radio communication system to which ARQ is applied, the channel estimation calculating means for obtaining a channel estimation value based on the phase fluctuation amount of a known symbol of a received signal, and the channel estimation value The first synchronous detection means for correcting the phase of the known symbol based on the error, the error bit detection means for calculating the number of error symbols of the known symbol after phase correction, and the magnitude relationship between the number of error symbols and the threshold value A weighting factor determining unit that determines a weighting factor based on the second synchronous detection unit that corrects the phase of the data of the received signal based on the channel estimation value, and the weighted factor multiplied by the data after phase correction A data buffer for storing received packets, a received packet received this time, and a received packet previously received and stored in the data buffer Taking the data synthesizing means for synthesizing and bets, the arrangement comprising a.

  The reception method of the present invention is a reception method used in a radio communication system to which ARQ is applied, and includes a step of obtaining a channel estimation value based on a phase fluctuation amount of a known symbol of a reception signal, and the channel estimation value A step of correcting the phase of the known symbol based on the step, a step of determining a weighting factor based on a magnitude relationship between the number of error symbols of the known symbol after the phase correction and a threshold value, and a received signal based on the channel estimation value Correcting the phase of the data, storing the received packet obtained by multiplying the determined weight coefficient by the phase-corrected data in a buffer, receiving the received packet this time and the previously received packet in the buffer And a step of combining the received packet stored in the method.

  According to the present invention, a received packet in which the soft decision value of a PL received symbol that cannot be correctly detected due to poor channel estimation quality is reduced and a received packet that has been previously received and subjected to the same processing are combined. By performing error correction, it is possible to prevent the quality of the combined packet from deteriorating. That is, a correct decoding result can be obtained by changing the weighting factor added to the soft decision value of the received packet according to the quality level of the channel estimation value. As a result, degradation of ARQ performance can be prevented.

  The receiving apparatus of the present invention combines a received packet in which the soft decision value of a PL received symbol, whose channel estimation value quality is poor and cannot be correctly detected, is reduced, and a received packet that has been previously received and subjected to similar processing. Error correction. As a result, it is possible to prevent the quality of the combined packet from being deteriorated, and as a result, it is possible to prevent the ARQ performance from being deteriorated even if the quality of the radio channel is deteriorated.

  Hereinafter, some embodiments of a receiving apparatus according to the present invention will be described in detail with reference to the drawings. In the drawings used in the embodiments, the same components are denoted by the same reference numerals, and redundant description is omitted as much as possible.

<Embodiment 1>
Hereinafter, the receiving apparatus according to Embodiment 1 of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a receiving apparatus according to Embodiment 1 of the present invention. First, the configuration of receiving apparatus 100 in Embodiment 1 shown in FIG. 1 will be described.

  Receiving apparatus 100 includes a receiving antenna 101 for receiving a received signal, a PL despreading unit 102 for despreading a PL received symbol of the received signal and its expected value, and a plurality of PL received symbols based on the amount of phase variation of each PL received symbol. A channel estimation calculation unit 103 that calculates an average value of the phase fluctuation amount of minutes to obtain a channel estimation value, a first synchronous detection unit 104 that corrects a phase with a channel estimation value for the PL reception symbol, and a PL reception symbol Error bit detection section 105 that counts the number of error symbols, weight coefficient determination section 106 that determines a weight coefficient based on the magnitude relationship between the number of error symbols and a threshold, and a data despreading section that despreads received signal data 107, a second synchronous detection unit 108 that corrects the phase of the data reception packet with a channel estimation value, and a weighting factor determination unit 106 A data buffer unit 109 that stores a data reception packet multiplied by a predetermined weighting factor, and a data synthesis unit that combines a reception packet received this time with a reception packet that has been received and stored in the data buffer unit 109 110, an error correction unit 111 that performs error correction and error determination on the received packet, a retransmission control unit 112 that outputs a retransmission request signal and outputs the hold information of the packet when there is an error in the received packet, and a transmission signal And a transmission unit 113 that outputs a retransmission request signal from the retransmission control unit 112.

  Next, the operation of receiving apparatus 100 shown in FIG. 1 will be described. The received signal input to the receiving antenna 101 is subjected to frequency conversion processing, filtering processing, and A / D conversion processing, and input to the PL despreading unit 102 and the data despreading unit 107. Then, the PL received symbol of the received signal despread by the PL despreading section 102 and its expected value are input to the channel estimation calculating section 103. Then, channel estimation calculation section 103 calculates the phase fluctuation amount of each PL reception symbol, and uses the average of the phase fluctuation amounts for a plurality of PL reception symbols as the channel estimation value.

  Next, the first synchronous detection unit 104 corrects the phase of the despread PL received symbol with the channel estimation value, and the error bit detection unit 105 further corrects the phase with the channel estimation value. The weight coefficient determination unit 106 determines the weight coefficient based on the magnitude relationship between the number of error symbols and the threshold value. Also, the second synchronous detector 108 corrects the phase with the channel estimation value for the data reception packet that has been despread. Further, the data buffer unit 109 stores the data reception packet multiplied by the weighting factor determined by the weighting factor determination unit 106.

  Further, when the data reception packet is a retransmission packet according to the information of the retransmission control unit 112, the data synthesis unit 110 receives the received packet received this time and the received packet previously received and stored in the data buffer unit 109. And outputs this combined packet to the error correction unit 111. On the other hand, if the received packet is not a retransmission packet according to the information of retransmission control section 112, data combining section 110 outputs the received packet from second synchronous detection section 108 to error correction section 111.

  Next, the error correction unit 111 performs error correction and error determination on the received packet from the data synthesis unit 110. Further, if there is an error in the received packet, retransmission control section 112 outputs a retransmission request to transmission section 113 and information indicating that the corresponding packet is held to data buffer section 109. Further, the transmission unit 113 outputs the retransmission request signal from the retransmission control unit 112 to the outside via the antenna 101 in addition to the conventional transmission signal.

  Next, the operation of receiving apparatus 100 shown in FIG. 1 will be specifically described using received packet information and PL received symbol information. FIG. 2 is a diagram in which received packet information and PL received symbol information are modeled for explaining the operation of the receiving apparatus shown in FIG. 1, and the time flow is shown in the horizontal direction of the figure. The received packet 200 shown in FIG. 2 indicates that packet information is received every fixed time, and the received packet 201 is an enlarged version of the received packet 200 and shows a state where the received packet is divided into a plurality of slots. ing. The PL received symbol 202 indicates a PL received symbol included in the received data, and a certain number of symbols is assigned to each slot.

  In the PL symbol 1 in the PL received symbol 202, the first synchronous detection unit 104 performs synchronous detection based on the channel estimation value obtained from the PL symbol 1 by the channel estimation value calculation unit 103, and further detects error bits. Unit 105 calculates the number of error bits for the expected value of PL symbol 1. Note that the channel estimation value and the number of error bits for each slot are calculated in the same manner for the PL symbol 2 and later.

  The received packet 1-1 in the received packet 201 is subjected to synchronous detection by the first synchronous detection unit 104 based on the channel estimation value obtained from the PL symbol 1 by the channel estimation value calculation unit 103. Then, error bit detection section 105 counts the number of PL symbol error bits per slot, and weight coefficient determination section 106 determines the weight coefficient based on the magnitude relationship between the number of error symbols and the threshold value. Then, the determined weighting coefficient is multiplied by the synchronous detection result of the received packet 1-1 and stored in the data buffer unit 109.

  Similarly, the detection results of the received packets 1-2 and later are stored in the data buffer unit 109 by multiplying the weighting factor calculated for each slot. For example, when the number of error bits is equal to or greater than a certain threshold, the weighting factor is set to “0”, and when the number of error bits is equal to or less than a certain threshold, the weighting factor is set to “1”. In this way, the weighting factor is determined by the number of PL symbol error bits per slot.

  Thus, according to Embodiment 1 of the present invention, the soft decision value when the channel estimation value cannot be calculated correctly due to noise or the like is reduced by setting the weighting factor for the received packet according to the quality of the channel estimation value. be able to. This increases the possibility that data can be correctly decoded by packet synthesis and error correction, thereby preventing an increase in the number of retransmissions.

<Embodiment 2>
Next, the receiving apparatus according to the second embodiment of the present invention will be described. FIG. 3 is a block diagram showing the configuration of the receiving apparatus according to Embodiment 2 of the present invention. In the receiving apparatus of FIG. 3, the same components as those of FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  3 is different from the receiving apparatus 100 of FIG. 1 in that a reception quality measuring unit 301 that measures reception quality using a despread symbol from the PL despreading unit 102 and a threshold value for determining a weighting factor. A threshold setting unit 302 that changes according to the reception quality is added.

  With such a configuration, reception quality measurement section 301 calculates reception quality using the despread symbols from PL despreading section 102, and threshold setting section 302 changes the threshold according to the reception quality. This makes it possible to determine the weighting factor according to the reception state, and to reduce the soft decision value when the channel estimation value cannot be calculated correctly.

  The receiving apparatus of the present invention is effective as a receiving apparatus used in a wireless communication system to which ARQ is applied because a correct decoding result can be obtained by changing the weighting factor added to the soft decision value of the received packet according to the quality of the channel estimation value. Can be used.

The block diagram which shows the structure of the receiver which concerns on Embodiment 1 of this invention. The figure which modeled the information of the received packet and the information of PL received symbol for description of operation | movement of the receiver shown in FIG. The block diagram which shows the structure of the receiver which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,300 Receiver 101 Reception antenna 102 PL despreading part 103 Channel estimation calculation part 104 1st synchronous detection part 105 Error bit detection part 106 Weight coefficient determination part 107 Data despreading part 108 2nd synchronous detection part 109 Data buffer Unit 110 data synthesis unit 111 error correction unit 112 retransmission control unit 113 transmission unit 301 reception quality measurement unit 302 threshold setting unit

Claims (4)

A receiving apparatus used in a wireless communication system applying ARQ,
Channel estimation calculation means for obtaining a channel estimation value based on a phase fluctuation amount of a known symbol of a received signal;
First synchronous detection means for correcting the phase of the known symbol based on the channel estimation value;
Error bit detection means for calculating the number of error symbols of the known symbol after phase correction;
Weighting factor determination means for determining a weighting factor based on the magnitude relationship between the number of error symbols and a threshold value;
Second synchronous detection means for correcting the phase of the data of the received signal based on the channel estimation value;
A data buffer for storing a reception packet obtained by multiplying the data after phase correction by the weighting factor;
Data combining means for combining the received packet received this time with the received packet previously received and stored in the data buffer;
A receiving device.   The receiving apparatus according to claim 1, wherein the channel estimation calculation unit calculates a phase fluctuation amount of each known symbol and averages the phase fluctuation amounts of a plurality of known symbols as a channel estimation value. A reception quality measuring means for measuring reception quality by a despread symbol of the received signal;
Threshold setting means for changing the threshold according to the reception quality measured by the reception quality measuring means;
The receiving apparatus according to claim 1 or claim 2, further comprising: A reception method used in a wireless communication system applying ARQ,
Obtaining a channel estimate based on the phase variation of a known symbol of the received signal;
Correcting the phase of the known symbol based on the channel estimate;
Determining a weighting factor based on a magnitude relationship between the number of error symbols of the known symbol after phase correction and a threshold;
Correcting the phase of the received signal data based on the channel estimate;
Storing the received packet obtained by multiplying the data after phase correction by the determined weighting factor in a buffer;
Combining the received packet received this time with the received packet previously received and stored in the buffer;
Including receiving method.

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