JP2006333346A - Radio communications apparatus, base station, mobile communication terminal, and data resending method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the throughput of the whole communications system, while effectively utilizing the transmission power resource at the time of resending by resending only a data zone required for characteristic improvement at packet compositing, without having to reduce the transmission efficiency of data. <P>SOLUTION: A NACK signal detecting portion 107 extracts a NACK signal from a received data outputted from a decoding portion 104 and informs it to a resending data determining portion 108. The resending data determining portion 108 acquires the TPC information informed, when base station received first time transmitted data from a TPC information maintaining portion 106, determines a data zone which should be resent based on the TPC information, and outputs it to a data buffer 109, when the NACK signal is informed from a NACK signal detection portion 107. A determination method of the resending data zone of the resending data determining portion 108, for example, determines to use as the resending data only the data zone, whose the TPC information was a transmission power Up. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a radio communication apparatus, a base station, a mobile communication terminal, and a data retransmission method.

  Conventionally, as a higher-speed IMT-2000 packet transmission method, HSUPA (High Speed Uplink Packet Access) / HSDPA (High Speed Downlink Packet Access) for the purpose of increasing the uplink / downlink peak transmission rate, increasing the throughput, etc. A method called "" has been studied. In a communication system employing these methods, HARQ (Hybrid Automatic Repeat reQuest) technology is used.

  HARQ is a technique that combines retransmission control and error correction. Taking HSDPA as an example, control is performed according to the following procedure. First, when a packet received at a mobile station is determined to be an error, a data retransmission request is automatically made to the base station. The base station requested for retransmission retransmits the corresponding packet to this mobile station. The mobile station that has received the retransmission data combines both the packet at the time of the initial transmission and the packet at the time of retransmission, increases the reception SIR (Signal to Interference Power Ratio) of the packet, and performs the decoding process.

  HARQ has a CC (Chase Combining) method adopted in 3GPP (3rd Generation Partnership Project). In the CC method, the same bit is transmitted when data is transmitted for the first time and when it is retransmitted. Then, by combining the data at the time of initial transmission and the data at the time of retransmission on the receiving side, the final SIR can be improved and the reception error rate can be improved.

As a conventional wireless communication system using HARQ, a wireless communication system that designates a bit for requesting retransmission to a mobile station based on a reception likelihood measured by a base station has been proposed (Patent Document 1). That is, in the wireless communication system of Patent Document 1, by not retransmitting bits that had good reception quality at the time of initial transmission, that is, bits that do not need to be retransmitted, the transmission power resource at the time of retransmission is effectively utilized, The throughput of the entire communication system is improved.
JP 2004-253959 A

  However, in the conventional apparatus, it is necessary to transmit bit designation information (bit number for requesting retransmission) without error. For this purpose, it is necessary to designate a plurality of retransmission bits, but the bit designation information is large. It becomes the amount of data. For this reason, when this bit designation information is transmitted as control information, there is a problem that the data transmission efficiency is lowered.

  The present invention has been made in view of this point, and retransmits only the data section necessary for improving the characteristics at the time of packet combining without reducing the data transmission efficiency, thereby reducing the transmission power resource at the time of retransmission. An object of the present invention is to provide a radio communication device, a base station, a mobile communication terminal, and a data retransmission method that can be used effectively and can improve the throughput of the entire communication system.

  The wireless communication apparatus according to the present invention includes a retransmission request signal detection unit that detects a retransmission request signal from a counterpart station and a transmission power control signal detection unit that detects a transmission power control signal from the counterpart station with respect to a transmitted packet. And retransmission data determination means for determining data to be retransmitted to the counterpart station based on the retransmission request signal detected by the retransmission request signal detection means and the transmission power control signal detected by the transmission power control signal detection means The structure which comprises these is taken.

  The data retransmission method of the present invention includes a step of detecting a retransmission request signal from a counterpart station for a transmitted packet, a step of detecting a transmission power control signal from the counterpart station, and the detected retransmission request signal, And a step of determining data to be retransmitted to the counterpart station based on the transmission power control signal.

  According to the present invention, it is possible to effectively use the transmission power resource at the time of retransmission by retransmitting only the data section necessary for the characteristic improvement at the time of packet synthesis without reducing the data transmission efficiency, Throughput of the entire communication system can be improved.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The embodiment of the present invention will be described by taking uplink high-speed packet transmission such as 3GPP HSUPA as an example. In this embodiment, a case where the CC method is used in HARQ will be described. That is, a retransmission method is assumed in which the same data is transmitted during the initial transmission of data and during retransmission. Also, it is assumed that the transmission power control period is shorter than the packet length as in 3GPP HSUPA and HSDPA (packet length: 10 ms or 2 ms in HSUPA, transmission power period: 0.667 ms, packet length: 2 ms in HSDPA) Transmission power cycle: 0.667 ms).

(Embodiment)
FIG. 1 is a block diagram showing a configuration of mobile communication terminal 100 provided with a wireless communication apparatus according to an embodiment of the present invention. The mobile communication terminal 100 includes an antenna 101, a radio unit 102, a demodulation unit 103, a decoding unit 104, a TPC information detection unit 105, a TPC information holding unit 106, a NACK signal detection unit 107, a retransmission data determination unit 108, a data buffer 109, An encoding unit 110, a modulation unit 111, and a transmission power control unit 112 are included.

  Radio section 102 performs predetermined radio reception processing such as down-conversion on the signal received via antenna 101, and outputs the result to demodulation section 103. Demodulation section 103 demodulates the signal output from radio section 102 and outputs it to decoding section 104. Decoding section 104 performs decoding processing such as error correction on the demodulated signal output from demodulation section 103 to obtain received data. The TPC information detection unit 105 serving as a transmission power control signal detection unit, from the reception data output from the decoding unit 104, transmits transmission power control information (hereinafter referred to as “TPC”) that is transmission power Up or transmission power Down information instructed by the base station. Information ”) and output to the TPC information holding unit 106 that holds the TPC information and the transmission power control unit 112 that controls the transmission power according to the transmission power control information.

  The NACK signal detection unit 107 serving as a retransmission request signal detection unit extracts a NACK signal (Negative Acknowledgment: retransmission request signal) from the reception data output from the decoding unit 104 and notifies the retransmission data determination unit 108 of the NACK signal. When the NACK signal is notified from the NACK signal detecting unit 107, the retransmission data determining unit 108 acquires the TPC information notified when the base station receives the initial transmission data from the TPC information holding unit 106, and the TPC information is obtained. Based on this, a data section to be retransmitted is determined and output to the data buffer 109. For example, the retransmission data determination unit 108 determines the retransmission data section so that only the data section in which the TPC information is the transmission power Up is used as the retransmission data.

  On the other hand, transmission data is first stored in the data buffer 109. The data buffer 109 outputs all data of one packet to the encoding unit 110 at the time of initial transmission, and outputs retransmission packet data in the data section designated by the retransmission data determination unit 108 at the time of packet retransmission. The encoding unit 110 performs encoding processing such as error correction encoding on the transmission packet output from the data buffer 109 and outputs the result to the modulation unit 111. Modulation section 111 performs modulation processing on the encoded signal output from encoding section 110 and outputs the result to transmission power control section 112. The transmission power control unit 112 controls the transmission power of the modulated signal output from the modulation unit 111 according to the TPC information instructed by the base station acquired from the TPC information detection unit 105, and outputs it to the radio unit 102. Radio section 102 performs predetermined radio transmission processing such as up-conversion on the signal output from transmission power control section 112 and transmits the signal to the base station via antenna 101.

  Next, a communication procedure between the mobile communication terminal 100 having the above configuration and the base station 200 will be described with reference to FIG. FIG. 2 is a sequence diagram showing operations of mobile communication terminal 100 and base station 200.

  Transmission data and control data are transmitted from mobile communication terminal 100 to base station 200 (ST201). Base station 200 receives this (ST202) and performs demodulation and decoding processing. The reception SIR obtained from the control signal is compared with the target SIR, TPC information (transmission power Up or Down) is determined, and transmitted to the mobile communication terminal 100. This TPC information is transmitted every transmission power control period (ST203-0 to ST203-N). Further, error detection is performed on the decoded packet, and the result is transmitted to mobile communication terminal 100 (ST204). For example, when the reception OK / NG is determined by the CRC determination and the received packet is determined to be an error, a NACK signal is transmitted to the mobile communication terminal 100. Mobile communication terminal 100 receives the signal transmitted from base station 200 (ST205), performs demodulation and decoding processing, and detects N TPC information and NACK signal of the packet transmitted at the time of packet reception (ST206). . When a NACK signal is detected, that is, when there is a retransmission request, a data interval for retransmitting a packet is determined based on N pieces of TPC information (ST207). Here, if the amount of data to be retransmitted is less than the number of packets, the spreading factor and coding rate are lowered, the redundancy is increased, and the transmission power is lowered (ST208). Base station 200 receives the retransmission packet, combines it with the initial packet, and performs decoding (ST209).

  Next, the operation of mobile communication terminal 100 according to the embodiment of the present invention will be described using FIG. FIG. 3 is a diagram for explaining the operation of the mobile communication terminal 100, and is a diagram showing the variation of the received SIR measured from the control signal when the base station 200 receives the initial transmission packet from the mobile communication terminal 100.

  As shown in FIG. 3, even if the transmission power is constant, the reception SIR 300 differs because the radio signal is fading in the propagation path. The reception SIR 300 is calculated every transmission power control period, and compared with the target SIR 301 to obtain TPC information. In other words, when the received SIR 300 is larger than the target SIR 301, the TPC information 302 indicates transmission power Down. When the received SIR 300 is smaller than the target SIR 301, the TPC information 303 indicates transmission power Up. Thus, the TPC information correlates with the quality of the received SIR.

  Therefore, since it is considered that data having a low received SIR causes an error at the time of packet decoding, in the present embodiment, the mobile communication terminal 100 determines the initial transmission packet based on the TPC information notified from the base station 200. A data section having a bad reception SIR is estimated, and only the data section is retransmitted. In this way, by retransmitting only the data necessary to compensate for the degradation of the initial packet, it is possible to effectively utilize the transmission power resource at the time of retransmission. Here, the data section is the same as the transmission power control cycle. For example, when the packet length is 10 ms, the transmission power cycle is 0.667 ms, and one packet is 150 bits, the data interval is 10 bits. Therefore, the retransmitted data is a data unit smaller than one packet.

  Then, the base station 200 combines the retransmission packet with the initial packet and performs decoding. At this time, the base station 200 must determine a data interval to be retransmitted. The determination method may determine, for example, which data section is retransmitted from the TPC information transmitted from the base station 200 itself to the mobile communication terminal 100. Further, since the TPC information notified from the base station 200 to the mobile communication terminal 100 may be erroneous in the propagation path, the mobile communication terminal 100 may notify the base station 200 which data section is retransmitted as control information. Good. At this time, since the control information is newly added, the data transmission efficiency is slightly reduced, but the error rate characteristic at the time of packet synthesis can be further improved.

  As described above, according to the present embodiment, the transmission power resource at the time of retransmission is effectively used by retransmitting only the data section necessary for improving the characteristics at the time of packet combining without reducing the data transmission efficiency. And the throughput of the entire communication system can be improved.

  In the above embodiment, the case where the radio communication apparatus according to the present invention is used for a mobile communication terminal has been described. However, the present invention is not limited to this and may be used for a base station.

  The radio communication apparatus, base station, mobile communication terminal, and data retransmission method according to the present invention are suitable for retransmitting data.

The block diagram which shows the structure of the mobile communication terminal which comprises the radio | wireless communication apparatus which concerns on embodiment of this invention The sequence diagram which shows operation | movement with the mobile communication terminal which comprises the radio | wireless communication apparatus which concerns on embodiment of this invention, and a base station The figure explaining operation | movement of the mobile communication terminal which comprises the radio | wireless communication apparatus which concerns on embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Mobile communication terminal 101 Antenna 102 Radio | wireless part 103 Demodulation part 104 Decoding part 105 TPC information detection part 106 TPC information holding part 107 NACK signal detection part 108 Retransmission data determination part 109 Data buffer 110 Encoding part 111 Modulation part 112 Transmission power control part

Claims (5)

Retransmission request signal detecting means for detecting a retransmission request signal from the counterpart station for the transmitted packet;
Transmission power control signal detection means for detecting a transmission power control signal from the counterpart station;
Based on the retransmission request signal detected by the retransmission request signal detection means and the transmission power control signal detected by the transmission power control signal detection means, retransmission data determination means for determining data to be retransmitted to the counterpart station;
A wireless communication apparatus comprising:   2. The wireless communication apparatus according to claim 1, wherein the retransmission data determination means determines to retransmit only data in a data section in which the received transmission power control information is instructed to increase transmission power.   A base station comprising the wireless communication device according to claim 1.   A mobile communication terminal comprising the wireless communication device according to claim 1. Detecting a retransmission request signal from the other station for the transmitted packet;
Detecting a transmission power control signal from the counterpart station;
Determining data to be retransmitted to the counterpart station based on the detected retransmission request signal and the transmission power control signal;
A data retransmission method comprising:

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