WO2006038595A1

WO2006038595A1 - Base station device and packet communication method

Info

Publication number: WO2006038595A1
Application number: PCT/JP2005/018307
Authority: WO
Inventors: Isamu Yoshii; Akihiko Nishio; Atsushi Matsumoto; Jun Cheng; Kenichi Miyoshi
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2004-10-04
Filing date: 2005-10-03
Publication date: 2006-04-13
Also published as: BRPI0516458A; JPWO2006038595A1; KR20070108848A; CN101027930A

Abstract

There is provided a base station device capable of improving the throughput of the entire system. The base station device (100) performs packet communication with a communication terminal (150) to which a time slot is allocated. An interference distribution information decoding unit (104) acquires information on the distribution of the interference signal to the terminal (150) on a frequency axis. When the distribution of the interference signal of the terminal (150) reaches a particular level, a scheduler (107) evades transmission of a retransmission packet between the base station device (100) and the terminal (150) by a packet communication different from the transmission of the retransmission packet to/from the terminal (150).

Description

Specification

Base station apparatus and packet communication method

Technical field

TECHNICAL FIELD [0001] The present invention relates to a base station apparatus that performs packet communication with a communication terminal apparatus and a bucket communication method thereof.

Background art

[0002] A technique called scheduling is used for a packet transmission method in which a plurality of communication terminal apparatuses transmit a packet on a line shared by time division. Scheduling is a technique in which a base station apparatus assigns communication terminal apparatuses for each time slot.

[0003] Hereinafter, a general packet transmission scheme will be described taking a downlink packet transmission scheme as an example. The communication terminal device that received the packet transmits an ACK signal or NACK signal depending on whether or not the packet has been correctly demodulated, and when the base station device receives the ACK signal, a packet different from that packet (new When a NACK signal is received, the same packet (retransmission packet) is retransmitted.

[0004] The communication terminal device that is the transmission destination of the packet, that is, the communication terminal device to which the time slot is allocated, is selected from among the plurality of communication terminal devices that share the line. Determined based on quality. For example, in the conventional base station device described in Patent Document 1, a packet is transmitted to a communication terminal device having the best reception quality among a plurality of communication terminal devices.

Patent Document 1: JP 2004-80165 A

Disclosure of the invention

Problems to be solved by the invention

However, in the conventional base station apparatus described above, the communication terminal apparatus that is the packet transmission destination is simply determined based on the reception quality, that is, the communication terminal apparatus having the best reception quality is determined as the packet transmission destination. Therefore, the allocation probability of a certain communication terminal device tends to be higher than that of other communication terminal devices. That is, while packet transmission to a certain communication terminal device is frequent, packet transmission to other communication terminal devices is low. Sometimes.

[0006] By the way, when an error occurs in a packet transmitted to a certain communication terminal device, a retransmission packet is transmitted to the communication terminal device, but the error can be corrected by retransmission. In other words, the communication terminal apparatus having the highest possibility of obtaining the retransmission effect is not necessarily the communication terminal apparatus having the best reception quality. Therefore, even if a packet is retransmitted to a communication terminal apparatus having a high allocation probability, a situation may occur in which retransmission is repeated many times without error correction. Therefore, in packet communication performed in a conventional base station apparatus, there is a certain limit to improving the throughput of the entire system.

An object of the present invention is to provide a base station apparatus and a packet communication method that can improve the throughput of the entire system.

Means for solving the problem

[0008] The base station apparatus of the present invention includes terminal allocation means for allocating a time slot to a first terminal apparatus among a plurality of terminal apparatuses, and information relating to dispersion on the frequency axis of interference signals for the first terminal apparatus And when the dispersion of the interference signal of the first terminal device is equal to or higher than a specific level, a packet different from the retransmission packet addressed to the first terminal device is assigned to the time slot, and A configuration is adopted that includes packet allocating means for avoiding retransmission packets addressed to the first terminal apparatus being assigned to the time slot, and transmitting means for transmitting the packet assigned to the time slot.

The invention's effect

According to the present invention, the throughput of the entire system can be improved.

Brief Description of Drawings

FIG. 1 is a block diagram showing a configuration of a base station apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram showing a configuration of a communication terminal apparatus according to Embodiment 1 of the present invention.

FIG. 3 is a diagram for explaining an interference dispersion calculation method according to Embodiment 1 of the present invention;

FIG. 4 is a flowchart for explaining the operation of the scheduler according to the first embodiment of the present invention. FIG. 5A is a diagram for explaining a specific operation example of the scheduler according to the first embodiment of the present invention. FIG. 5B is a diagram for explaining a specific operation example of the scheduler according to Embodiment 1 of the present invention.

FIG. 5C is a diagram for explaining a specific operation example of the scheduler according to Embodiment 1 of the present invention.

FIG. 5D is a diagram for explaining a specific operation example of the scheduler according to Embodiment 1 of the present invention.

[Fig. 6] Diagram for explaining the effect of packet retransmission on the magnitude of interference dispersion

[Fig.7] Diagram for explaining changes in signal power due to synthesis processing

FIG. 8 is a block diagram showing a configuration of a base station apparatus according to Embodiment 2 of the present invention.

FIG. 9 is a block diagram showing a configuration of a communication terminal apparatus according to Embodiment 2 of the present invention.

FIG. 10 is a block diagram showing a configuration of a base station apparatus according to Embodiment 3 of the present invention.

FIG. 11 is a flowchart for explaining the operation of the scheduler according to the third embodiment of the present invention.

FIG. 12A is a diagram for explaining a specific operation example of the scheduler according to Embodiment 3 of the present invention.

FIG. 12B is a diagram for explaining a specific operation example of the scheduler according to Embodiment 3 of the present invention.

FIG. 12C is a diagram for explaining a specific operation example of the scheduler according to Embodiment 3 of the present invention.

FIG. 12D is a diagram for explaining a specific operation example of the scheduler according to Embodiment 3 of the present invention.

FIG. 13 is a block diagram showing a configuration of a base station apparatus according to Embodiment 4 of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0012] (Embodiment 1)

FIG. 1 is a block diagram showing the configuration of the base station apparatus according to Embodiment 1 of the present invention. In addition, FIG. 2 shows a communication terminal device (hereinafter referred to as a packet communication device) that performs packet communication with the base station device 100 of FIG.

2 is a block diagram illustrating a configuration of “terminal”.

Base station apparatus 100 includes antenna 101, reception RF section 102, demodulation section 103, interference dispersion information recovery. Signal unit 104, ACKZNACK signal decoding unit 105, SINR information decoding unit 106, scheduler 107, packet generation instruction unit 108, buffer instruction unit 109, MCS (Modulation and Coding Scheme) instruction unit 110, multiplexing method instruction signal generation unit 111 A modulation unit 112, a packet generation unit 113, a notch 114, an error correction code unit 115, a modulation unit 116, a multiplexing unit 117, and a transmission RF unit 118. 2 includes an antenna 151, a reception RF unit 152, a demodulation unit 153, a synthesis unit 154, a nofer 155, an error correction decoding unit 156, an error detection unit 157, a switch unit 158, and an ACKZNACK signal generation. Unit 159, interference signal extraction unit 160, interference dispersion calculation unit 161, interference dispersion information generation unit 162, SINR (Signal to Interference and Noise Ratio) measurement unit 163, SINR information generation unit 164, modulation unit 165, and transmission RF unit 166 Have

In base station apparatus 100, reception RF section 102 receives an OFDM (Orthogonal Frequency Division Multiplexing) signal transmitted from n terminals 150 currently in communication via antenna 101, and converts the received signal into the OFDM signal. Then, predetermined radio processing is performed, and a baseband signal is output to the demodulation unit 103. Demodulation section 103 demodulates the OFDM signal output from reception RF section 102.

Interference dispersion information decoding section 104 serving as acquisition means decodes interference dispersion information indicating interference dispersion (described later) of each terminal 150 from the output signal of demodulation section 103 and outputs the decoded information to scheduler 107.

[0016] ACKZNACK signal decoding section 105 decodes an ACK (Acknowledgement) signal or NACK (Negative Acknowledgement) signal of each terminal 150 from the output signal of demodulation section 103, and outputs the decoding result to scheduler 107.

[0017] SINR information decoding section 106 decodes the SINR information of each terminal 150 from the output signal of demodulation section 103 and outputs it to scheduler 107.

[0018] Scheduler 107 receives the interference dispersion information of each terminal 150 input from interference dispersion information decoding section 104, the ACKZN ACK signal and SINR information decoding section 106 of each terminal 150 input from ACKZNACK signal decoding section 105, and so on. Based on the SINR information of each terminal 150, downlink packet communication scheduling is performed. In other words, the process of assigning time slots to any terminal 150 (terminal assignment) is performed for each time slot. More specifically, the scheduler 107, as a control means, transmits a retransmission packet to / from a terminal 150 when the interference dispersion of the terminal 150 to which the time slot is allocated is equal to or higher than a specific level. Control is performed to avoid retransmission packet transmission between the communication unit and its terminal 150 by causing the communication unit described later to perform packet communication different from the above. Also, as a terminal allocation means, a time slot is allocated to the terminal 150 having the largest SINR among the plurality of terminals 150. Also, as a packet allocation means, a new packet or retransmission packet is allocated to each time slot, and if the interference variance of the terminal 150 to which the time slot is allocated exceeds a specific level, it is different from the retransmission packet addressed to that terminal 150. A packet is assigned to the time slot, and a retransmission packet addressed to the terminal 150 is prevented from being assigned to the time slot.

[0020] In addition, after determining time slot allocation to any terminal 150, scheduler 107 determines a modulation scheme and a coding rate (MCS) based on the SINR information of that terminal 150, and performs MCS indication Part 110 is notified. Further, based on the above determination, the packet generation instructing unit 108 is notified of the terminal 150 to which the time slot is allocated and the data amount of the packet to be generated. In addition, terminal 150 to which the time slot is allocated and the ACK signal or NACK signal are notified to buffer instruction section 109. In addition, terminal 150 and MCS to which the time slot is allocated are notified to multiplexing method instruction signal generation section 111.

[0021] The packet generation instruction unit 108 instructs the packet generation unit 113 to generate a packet having a data amount notified from the scheduler 107, which is a packet addressed to the terminal 150 to which the time slot is assigned.

[0022] In accordance with an instruction from the packet generation instruction unit 108, the packet generation unit 113 uses data addressed to the terminal 150 to which the time slot is allocated (data # 1 to data _#n , which is a shift), and the terminal 150 A packet addressed to the address is generated and output to the buffer 114.

[0023] The noffer instruction unit 109 instructs the buffer 114 to select a packet addressed to the terminal 150 to which the time slot is assigned. In addition, when an ACK signal is input from the scheduler 107, the buffer 114 is instructed to delete a packet left in preparation for retransmission, and the packet generated by the packet generator 113 is stored in the buffer 114. Indicate. On the other hand, when a NACK signal is input from the scheduler 107, the input NACK Instructs the buffer 114 to leave a packet corresponding to the signal.

[0024] In accordance with the instruction from the buffer instruction unit 109, the noffer 114 selects a packet addressed to the terminal 150 to which the time slot is assigned. At this time, when an ACK signal is input to the nota instruction unit 109, the buffer 114 deletes the packet stored for retransmission and stores the packet generated by the packet generation unit 113 for retransmission. At the same time, it is output to the error correction code field 115. In addition, when a NACK signal is input to the notch 109, the buffer 114 outputs the packet stored for retransmission to the error correction code unit 115.

[0025] The MCS instruction unit 110 instructs the error correction code unit 115 of the code rate notified from the scheduler 107 and also instructs the modulation unit 116 of the modulation scheme notified from the scheduler 107.

The error correction code encoding unit 115 encodes the packet input from the nother 114 in accordance with an instruction from the MCS instruction unit 110 and outputs the packet to the modulation unit 116. Modulation section 116 performs OF DM modulation on the packet input from error correction code encoding section 115 in accordance with an instruction from MCS instruction section 110, and outputs the result to multiplexing section 117.

[0027] Multiplex method instruction signal generation section 111 generates a multiple method instruction signal indicating information related to terminal allocation and MCS. Modulation section 112 modulates the generated multiplexing method instruction signal. Multiplexing section 117 multiplexes each modulated packet and multiplexing method instruction signal. The transmission RF section 118 performs predetermined radio processing on the multiplexed OFDM signal, and transmits the radio signal after the radio processing to the packet transmission destination terminal 150 via the antenna 101.

That is, the combination of multiplexing method instruction signal generation section 111, modulation section 112, packet generation section 113, buffer 114, error correction code section 115, modulation section 116, multiplexing section 117, and transmission RF section 118 is In addition, a communication unit that performs packet communication with the terminal 150 to which the time slot is allocated is configured, and a transmission unit that transmits the packet allocated to the time slot is configured.

On the other hand, in terminal 150 in FIG. 2, reception RF section 152 receives an OFDM signal transmitted from base station apparatus 100 via antenna 151, and performs a predetermined process on the OFDM signal. Radio processing is performed, and a baseband signal is output to demodulation section 153. Demodulation section 153 demodulates the OFDM signal output from reception RF section 152.

[0030] Combining section 154 combines the output signal of demodulation section 153 and the signal stored in buffer 155, and outputs the combined signal obtained by the combining to buffer 155 and error correction decoding section 156. The buffer 155 outputs the stored signal to the synthesis unit 154 and overwrites and saves the new signal output from the synthesis unit 154.

[0031] Error correction decoding section 156 performs error correction decoding processing such as Viterbi decoding on the output signal of combining section 154, and outputs the result to error detection section 157 and switch section 158.

[0032] Error detection section 157 performs error detection (CRC determination) on the output signal of error correction decoding section 156, and outputs the error detection result to ACKZNACK signal generation section 159. If an error is detected by error detection, error detection section 157 disconnects switch section 158, and the output signal (received data) of error correction decoding section 156 is output to a device that performs a post-process not shown in the figure. To prevent that. On the other hand, when an error is detected by the error detection, the error detection unit 157 deletes the signal stored in the nota 155 and connects the switch unit 158. In this case, the output signal (received data) of error correction decoding section 156 is output to the device that performs the above-described subsequent process.

[0033] ACKZNACK signal generation section 159 generates an ACK signal or a NACK signal according to the error detection result input from error detection section 157. If no error is detected by error detection, an ACK signal is generated. On the other hand, if an error is detected, a NACK signal is generated. The generated ACK signal or NACK signal is output to modulation section 165.

[0034] SINR measurement section 163 measures SINR using the output signal of reception RF section 152. The S INR information generation unit 164 generates SINR information based on the SINR measurement result of the SINR measurement unit 163! /. The SINR information may indicate numbers that represent discrete SINR discretely, or may indicate measured values as they are. The generated SINR information is output to modulation section 165.

Interference signal extraction section 160 extracts a signal addressed to other terminal 150 from the output signal of demodulation section 153 as an interference signal for own terminal 150. That is, a signal obtained by removing a signal addressed to own terminal 150 from the received signal is extracted as an interference signal. The extracted interference signal is It is output to the interference variance calculation unit 161.

Interference dispersion calculation section 161 calculates the dispersion of interference signals on the frequency axis (hereinafter referred to as “interference dispersion”), in other words, the dispersion (nonuniformity) of interference power on the frequency axis. . The calculated interference variance is output to interference variance information generation section 162.

Here, the calculation of interference dispersion will be specifically described with reference to FIG. Here, the calculation of interference dispersion in the case of four subcarriers is illustrated. When the real value of the power for each subcarrier of the interference signal is [0.5, 0.5, 1.0, 2.0] as shown in Fig. 3, the interference variance is calculated by the following (Equation 1). In this example, the real value is calculated after setting the power of the third subcarrier to the reference value, but the method of setting the reference value is not limited to this.

10 X loglO (0.5 + 0.5 + 1.0 + 2.0) = 10 X loglO (4)

= 6 [dB]… (Formula 1)

[0038] Interference dispersion information generation section 162 generates interference dispersion information for notifying base station apparatus 100 of interference dispersion that is an output signal of interference dispersion calculation section 161. The generated interference dispersion information is output to modulation section 165.

Modulation section 165 performs OFDM modulation on the output signals of ACKZNACK signal generation section 159, interference dispersion information generation section 162, and SINR information generation section 164, and outputs the result to transmission RF section 166. Transmission RF section 166 performs predetermined radio processing on the OFDM signal output from modulation section 165, and transmits the radio signal after radio processing to base station apparatus 100 via antenna 151.

[0040] Hereinafter, an operation example of scheduler 107 of base station apparatus 100 having the above configuration will be described with reference to the flowchart of FIG.

First, in step ST 1001, normal scheduling is performed based on SINR information notified from each terminal 150. That is, a time slot is assigned to terminal 150 having the largest SINR.

[0042] Then, in step ST1002, based on the ACK signal or NACK signal notified from terminal 150 to which a time slot is allocated, the packet transmitted to terminal 150 is a new packet or a retransmission packet. Determine whether. [0043] As a result of the determination in step ST1002, if the packet transmitted to terminal 150 is a new packet (ST1002: NO), the new packet is directly assigned to the time slot (ST1003). Therefore, in this case, a new packet is transmitted.

On the other hand, when the packet addressed to terminal 150 is a retransmission packet (ST1002: YES), it is determined whether or not the interference dispersion in which terminal 150 power is also notified is greater than or equal to a predetermined threshold (ST1004). For example, the threshold value is set to a value obtained by adding a margin to the received average interference amount.

If the result of determination in step ST1004 is that the interference variance is less than the threshold (ST1004: NO), the retransmission packet is assigned to the time slot as it is (ST1005). Therefore, in this case, a retransmission packet is transmitted.

On the other hand, when the interference variance is equal to or greater than the threshold (ST1004: YES), the transmission of a new packet addressed to terminal 150 is determined and the data amount is notified to packet generation instructing section 108. Also, the generated new packet is assigned to the time slot (ST1006). Therefore, in this case, a new packet is transmitted.

[0047] Then, the retransmission packet from which transmission is avoided is assigned to the next transmission queue (ST100 7). At this time, the retransmission packet stored in the nother 114 is stored as it is and becomes a transmission candidate again in the next scheduling cycle. For example, when scheduling is performed every 2 msec, the flow in Fig. 4 is executed again 2 msec after transmission is avoided. If the interference variance becomes lower than the threshold at that time, the retransmission packet is transmitted.

Next, a specific operation example of the scheduler 107 will be described with reference to FIG.

[0049] Each SINR of terminals A to C in the section from time tl to tl7 is shown in (a). The scheduler 107 refers to these SINRs and assigns each time slot in the transmission queue corresponding to this section to any of the terminals A to C. The result of this assignment is shown in (b). Specifically, at time tl to t3, terminal A has the highest SINR, so a time slot is assigned to terminal A, and at time t4 to t6, terminal B has the highest SINR, so terminal B has a time slot. At time t7-9, terminal A has the highest SINR, so time slot is assigned to terminal A, and at time tlO-tl3, terminal B has the highest SINR, so time slot is assigned to terminal B. At time tl4 to tl7 Since the SINR is the highest, a time slot is assigned to terminal C.

[0050] Also, as shown in (b), scheduler 107 newly creates a packet addressed to a terminal to which each time slot is assigned based on the ACK signal or NACK signal from each terminal A to C. It is determined whether it should be a packet or a retransmission packet. In this example, the packets corresponding to the time slots at times t3, t6, t8, t9, and tl2 to tl5 are retransmission packets.

[0051] Then, the scheduler 107 refers to the interference dispersion of the terminals A to C in the section from time tl to tl7. These interference variances are shown in (c). According to the notified interference dispersion, the interference dispersion of terminal A at times t5 to tl7 is equal to or greater than the threshold value.

[0052] Therefore, as shown in (d), transmission of a retransmission packet addressed to terminal A at times t8 and t9 is avoided. Instead, at time t8 and t9, a new packet is addressed to terminal A. A new packet destined for terminal A is assigned to the time slot at times t8 and t9 so that the transmission is performed. The retransmitted packet whose transmission has been avoided is assigned to the transmission queue corresponding to the section after time tl8.

Here, the magnitude of the effect of packet retransmission on the magnitude of interference dispersion will be described.

FIG. 6 shows the normalized throughput for each SINR. Curve D shows the case where the interference signal is the same as that of stationary thermal noise and the variance is lower than a predetermined level and is a signal (hereinafter referred to as “white signal”), and ARQ (Automatic Repeat Request) control is performed. Shows the throughput of the case. Curve D is when the interference signal is a white signal and ARQ control is performed.

2

Shows the throughput when trapping. Curve D shows that the interference signal differs from stationary thermal noise.

Three

This shows the throughput when ARQ control is performed for a signal with a variance equal to or higher than a predetermined level (hereinafter defined as “colored signal”). Curve D shows that the interference signal is colored

Four

In this case, the throughput is shown when the ARQ control is used.

[0055] When the normalized throughput of one terminal (UE1) and the normalized throughput of the other terminal (UE2) are approximately the same (about 0.3), the interference signal for UE1 is a colored signal and for U E2 A case where the interference signal is a white signal will be described as an example. For UE2, since the interference signal is a white signal, the magnitude of the SINR improvement with ARQ control compared to the case without ARQ control, that is, the packet retransmission effect is about 3 dB, while the UE For 1, the interference signal is a colored signal, so the packet retransmission effect is about ldB

[0056] When the interference signal is a white signal, as shown in Fig. 7, the power (Pd) of the desired signal (S) after synthesis is equal to the power (Pa) of the desired signal (S) at the time of new transmission. This is the sum of the power (Pa) of the desired signal (S) at the time of retransmission. On the other hand, the power (Pe—Pd) of the synthesized noise signal (N) is the power of the noise signal (N) at the time of new transmission (Pb—Pa) and the power of the noise signal (N) at the time of retransmission (Pb-Pa). ) Respectively. Also, the power (Pf—Pe) of the combined interference signal (I) is the power (Pc—Pb) of the interference signal (I) at the time of new transmission and the power (P c−Pb) of the interference signal (I) at the time of retransmission. Each is equivalent to Pb).

[0057] However, when the interference signal is a colored signal, the interference signal is the power (Pd) of the desired signal (S) after synthesis and the power (Pe-Pd) of the noise signal (N) after synthesis. As with the white signal, since the interference signal (I) is a colored signal, the power (Pg—Pe) of the combined interference signal (I) is equal to that of the interference signal (I) at the time of new transmission. This is the sum of the power (Pc – Pb) and the power (Pc – Pb) of the interference signal (I) during retransmission. Therefore, when the interference signal is a colored signal, the SINR improvement effect by packet retransmission is smaller than when the interference signal is a white signal.

Therefore, even if the SINR of a certain terminal is high, the effect of packet retransmission is small if the interference variance of that terminal is large. For this reason, a terminal assigned by normal scheduling compares the interference dispersion with a threshold value, and when the interference dispersion is less than the threshold value, avoids transmission of a retransmission packet addressed to that terminal, and By sending new packets, throughput can be improved.

[0059] Thus, according to the present embodiment, when the interference variance of terminal 150 to which a time slot is assigned is equal to or greater than the threshold, a new packet addressed to terminal 150 is assigned to the time slot, and terminal 150 is assigned. In order to avoid that the retransmission packet addressed to the time slot is assigned, it is possible to avoid the retransmission of the retransmission packet from the base station apparatus 100 to the terminal 150 having a small retransmission effect repeatedly, and in the downlink. In a system using a packet transmission method, the throughput of the entire system can be improved.

[0060] (Embodiment 2) FIG. 8 is a block diagram showing the configuration of the base station apparatus according to Embodiment 2 of the present invention. FIG. 9 is a block diagram showing a configuration of the terminal according to the present embodiment. Note that base station apparatus 200 in FIG. 8 and terminal 250 in FIG. 9 have the same basic configuration as base station apparatus 100 and terminal 150 described in Embodiment 1, respectively. Therefore, the same components as those described in Embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

[0061] Base station apparatus 200 has GIVEUP signal decoding section 201 and scheduler 202 instead of interference dispersion information decoding section 104 and scheduler 107 described in Embodiment 1.

[0062] GIVEUP signal decoding section 201 as an acquisition means decodes a GIVEUP signal indicating that the interference dispersion of any terminal 250 is above a specific level from the output signal of demodulation section 103, and scheduler 202 Output to.

The scheduler 202 has the same basic configuration as the scheduler 107. If the scheduler 202 uses the GIVEUP signal of any terminal 250 input from the GIVEUP signal decoding unit 201 instead of the interference dispersion information, it is different from the scheduler 107!

Terminal 250 in FIG. 9 has GIVEUP signal generation section 251 instead of interference dispersion information generation section 162 described in Embodiment 1.

[0065] GIVEUP signal generation section 251 stores in advance a predetermined threshold value used for comparison with interference dispersion that is an output signal of interference dispersion calculation section 161. This threshold value is the same as the threshold value used by the scheduler 107 described in Embodiment 1 for comparison with interference dispersion. Then, compare the interference variance with its threshold. As a result of the comparison, if the interference variance is greater than or equal to the threshold value, a GIVEUP signal is generated. The generated GIVEUP signal is output to modulation section 165 and subjected to OFDM modulation by modulation section 165. The GIVEUP signal is a signal for notifying the base station apparatus 200 that the interference dispersion is equal to or greater than the threshold value, and for causing the base station apparatus 200 to avoid transmission of a retransmission packet addressed to the terminal 250 itself.

[0066] Thus, according to the present embodiment, the same operational effects as in Embodiment 1 can be realized, and only when the interference dispersion of terminal 250 is greater than or equal to the threshold value, notification to that effect is given to base station apparatus 200. Therefore, the amount of signaling information can be reduced. [Embodiment 3]

FIG. 10 is a block diagram showing the configuration of the base station apparatus according to Embodiment 3 of the present invention. Note that base station apparatus 300 in FIG. 10 has the same basic configuration as base station apparatus 100 described in the first embodiment, and has the same constituent elements as those described in the previous embodiment. The detailed description is abbreviate | omitted. Base station apparatus 300 performs packet communication with terminal 150 described in the first embodiment.

[0068] Base station apparatus 300 includes scheduler 301 instead of scheduler 107 described in the first embodiment.

[0069] The scheduler 301 has the same basic configuration as the scheduler 107, but is different from the scheduler 107 in the configuration as a terminal allocation unit. That is, scheduler 301 assigns a time slot to terminal 150 having the maximum SINR among a plurality of terminals 150, and differs from terminal 150 when the interference variance of terminal 150 to which the time slot is assigned exceeds a specific level. Assign a time slot to terminal 150.

Hereinafter, an operation example in the scheduler 301 will be described with reference to the flowchart of FIG.

[0071] In steps ST1001 to ST1005, the same processing as in the first embodiment is performed.

[0072] If the result of determination in step ST1004 is that the interference variance is greater than or equal to a threshold (ST1004: YES), it is determined whether or not the number of times the terminal 150 to which the time slot is allocated has changed reaches a predetermined value (ST2001). ). Note that the value used for comparison with the number of changes may be the number n of terminals 150 currently in communication, or an arbitrary integer smaller than n.

[0073] As a result of the determination in step ST2001, if the number of changes has not reached the predetermined value (ST2 002: NO), the terminal 150 to which the time slot is allocated is the terminal 150 (that is, the current processing target) The terminal is changed to the terminal 150 having the next highest SINR after the terminal 150) to which the time slot is allocated (ST2002).

[0074] Then, in step ST2003, the same processing as ST1007 described in the first embodiment is performed. That is, the retransmission packet for which transmission has been avoided is assigned to the next transmission queue.

[0075] If the number of changes reaches the predetermined value as a result of the determination in step ST2001 (ST2002: YES), terminal 150 selected in step ST1001, that is, the maximum SINR end A new packet addressed to end 150 is assigned to a time slot (ST2004). As a result, when the terminal 150 that can achieve a certain retransmission effect does not exist in the predetermined number of terminals 150, a new packet is sent to the terminal 150 to which the time slot was initially assigned, that is, the terminal 150 with the maximum SINR. Can be sent.

Next, a specific operation example of the scheduler 301 will be described with reference to FIG.

[0077] Each SINR of terminals A to C in the section from time tl to tl7 is shown in (a). The scheduler 301 refers to these SINRs and assigns each time slot in the transmission queue corresponding to this section to any of the terminals A to C. The result of this assignment is shown in (b). Specifically, at time tl to t3, terminal A has the highest SINR, so a time slot is assigned to terminal A, and at time t4 to t6, terminal B has the highest SINR, so terminal B has a time slot. At times t7-9, terminal A has the highest SINR, so time slot is assigned to terminal A, and at times tl0-tl3, terminal B has the highest SINR, so time slot is assigned to terminal B. At times tl4 to tl7, since the terminal SINR is the highest, a time slot is assigned to terminal C.

[0078] Also, as shown in (b), in scheduler 301, a packet addressed to a terminal assigned with each time slot is a new packet based on the ACK signal or NACK signal from each terminal A to C. Or retransmission packet. In this example, packets corresponding to time slots at times t3, t6, t8, t9, and tl2 to tl5 are retransmission packets.

[0079] Then, the scheduler 301 refers to the interference dispersion of the terminals A to C in the section from time tl to tl7. These interference variances are shown in (c). According to the notified interference dispersion, the interference dispersion of terminal A at times t5 to tl7 is equal to or greater than the threshold value.

[0080] For this reason, as shown in (d), transmission of a retransmission packet addressed to terminal A at times t8 and t9 is avoided. Instead, at time t8 and t9, the next highest SINR after terminal A is avoided. Packet addressed to terminal B is assigned to the time slot at times t8 and t9 so that the packet is transmitted to terminal B having The retransmitted packet destined for terminal A that was avoided from transmission is assigned to the transmission queue corresponding to the section after time tl8. In this example, the packet addressed to terminal B assigned at times t8 and t9 is a new packet, but when processing is performed according to the flow in FIG. 11, a retransmission packet addressed to terminal B is assigned. Sometimes It is clear that this is possible.

As described in Embodiment 1 with reference to FIGS. 6 and 7, even if the SINR of a certain terminal is high, the effect of packet retransmission is small if the interference dispersion of that terminal is large. For this reason, the interference variance for a terminal assigned by normal scheduling is compared with a threshold, and if the interference variance is less than the threshold, transmission of a retransmission packet addressed to that terminal is avoided, and packets destined for other terminals are You can send.

Thus, according to the present embodiment, it is possible to improve throughput by transmitting packets to terminal 150 different from terminal 150 having a small retransmission effect.

[0083] (Embodiment 4)

FIG. 13 is a block diagram showing the configuration of the base station apparatus according to Embodiment 4 of the present invention. Note that base station apparatus 400 in FIG. 13 has the same basic configuration as base station apparatus 100 described in the first embodiment, and is identical to the same components as those described in the previous embodiment. The detailed description is abbreviate | omitted. Base station apparatus 400 performs packet communication with terminal 250 described in the second embodiment.

[0084] Base station apparatus 400 has GIVEUP signal decoding section 201 described in Embodiment 2 instead of interference dispersion information decoding section 104 described in Embodiment 1, and includes scheduler 107 described in Embodiment 1. Instead of the scheduler 401.

[0085] Scheduler 401 has the same basic configuration as scheduler 301 described in the third embodiment. The scheduler 401 is different from the scheduler 301 when the GIVEUP signal of the other terminal 250 is used instead of the interference dispersion information and the GIVEUP signal of the terminal 250 is input.

[0086] Thus, according to the present embodiment, the same operational effects as in Embodiment 3 can be realized, and notification is made to base station apparatus 400 only when the interference dispersion of terminal 250 is greater than or equal to the threshold value. Therefore, the amount of signaling information can be reduced.

It should be noted that each of the above-described embodiments has been described by taking the case of scheduling packet transmission on the downlink as an example. The present invention is also applied to scheduling of packet transmission on the uplink. Can do. That is, if the interference variance of a terminal to which a time slot is allocated is greater than or equal to a threshold value, a different transmission from that for retransmission packet transmission to that terminal. In order to avoid retransmission of retransmission packets by causing the communication unit to perform packet communication, it is possible to avoid repeated retransmission of retransmission packets between the base station apparatus and a terminal having a small retransmission effect. And the throughput of the entire system can be improved.

[0088] Each functional block used in the description of each embodiment is typically realized as an LSI which is an integrated circuit. These may be individually made into one chip, or may be made into one chip to include some or all of them.

[0089] Here, it is sometimes called an IC, a system LSI, a super LSI, or a monolithic LSI, depending on the difference in power integration as LSI.

[0090] Further, the method of circuit integration is not limited to LSI's, and implementation using dedicated circuitry or general purpose processors is also possible. It is also possible to use a field programmable gate array (FPGA) that can be programmed after LSI manufacture and a reconfigurable processor that can reconfigure the connection and settings of circuit cells inside the LSI.

[0091] Further, if integrated circuit technology that replaces LSI appears as a result of the advancement of semiconductor technology or a derivative other technology, it is naturally also possible to carry out function block integration using that technology. Biotechnology can be applied.

[0092] When the error correction code key unit 115 performs an error correction code key using a systematic code such as a turbo code or an LDPC code, a systematic bit that is a transmission bit itself by the code key, Redundancy bits, NORITY bits, are generated. Therefore, in Embodiments 1 and 3, a new packet is replaced with a packet including both systematic bits and parity bits, and the present invention is implemented using a packet including only the NORMAL bit as a retransmission packet. Yo ... A bucket that contains both systematic and parity bits is a packet that can be decoded independently, as well as a new packet, while a packet that contains only the NORITY bit is a packet that cannot be decoded alone.

[0093] This specification is based on Japanese Patent Application No. 2004-291814 filed on Oct. 4, 2004.

All this content is included here.

Industrial applicability

The base station apparatus and packet communication method of the present invention are useful for performing packet communication with a terminal.

Claims

The scope of the claims

[1] a terminal allocation unit that allocates a time slot to a first terminal device among a plurality of terminal devices, an acquisition unit that acquires information on dispersion on the frequency axis of an interference signal for the first terminal device;

If the dispersion of the interference signal of the first terminal device is a specific level or higher, a packet different from the retransmission packet addressed to the first terminal device is assigned to the time slot, and the retransmission packet addressed to the first terminal device Packet allocating means for avoiding being allocated to the time slot;

Transmitting means for transmitting a packet assigned to the time slot;

A base station apparatus.

[2] The packet allocation means includes:

When the dispersion of the interference signal of the first terminal device is equal to or higher than the specific level, a new packet addressed to the first terminal device or a packet including both systematic bits and parity bits is allocated to the time slot. ,

The base station apparatus according to claim 1.

[3] The terminal allocation means includes

If the dispersion of the interference signal of the first terminal device is equal to or higher than the specific level, a terminal device to which the time slot is assigned is a second terminal different from the first terminal device among the plurality of terminal devices. Change to device,

The base station apparatus according to claim 1.

[4] The packet allocation means includes:

Assigning a new packet addressed to the second terminal device or a packet including both systematic bits and parity bits to the time slot;

The base station apparatus according to claim 3.

[5] The acquisition means includes:

Further acquiring information on dispersion on the frequency axis of the interference signal for the second terminal device, The packet allocation means includes

If the variance of the interference signal of the second terminal device is less than the specific level, a retransmission packet addressed to the second terminal device is assigned to the time slot.

The base station apparatus according to claim 3.

[6] The terminal allocation means includes:

A terminal device having a reception quality next to the first terminal device is selected as the second terminal device among the plurality of terminal devices;

The base station apparatus according to claim 3.

[7] The terminal allocation means includes:

A terminal device having the second highest priority after the first terminal device among the plurality of terminal devices is selected as the second terminal device;

The base station apparatus according to claim 3.

[8] The acquisition means includes:

Further obtaining information on dispersion on the frequency axis of interference signals for each of a plurality of terminal devices different from the first terminal device among the plurality of terminal devices,

The packet allocation means includes

When dispersion of interference signals of a plurality of terminal devices different from the first terminal device is equal to or higher than the specific level, a new packet addressed to the first terminal device or both systematic bits and parity bits Is assigned to the time slot,

The base station apparatus according to claim 1.

[9] a communication means for performing packet communication with a terminal device to which a time slot is allocated;

An acquisition means for acquiring information on dispersion on a frequency axis of an interference signal for the terminal device;

When the dispersion of interference signals of the terminal device is equal to or higher than a specific level, the communication unit performs packet communication different from transmission of a retransmission packet with the terminal device, and the communication unit and the terminal device A control means for performing control to avoid transmission of retransmission packets between A base station apparatus.

[10] An acquisition step of acquiring information on dispersion on the frequency axis of an interference signal for a terminal device to which a time slot is assigned among a plurality of terminal devices;

If the dispersion of the interference signal of the terminal device is a specific level or higher, a packet different from the retransmission packet addressed to the terminal device is assigned to the time slot, and the retransmission packet addressed to the first terminal device is assigned to the time slot. A packet allocation step to avoid being allocated;

A transmission step of transmitting a packet assigned to the time slot; and a packet communication method.

[11] A packet communication method used when packet communication is performed between a base station device and a terminal device to which a time slot is assigned,

Obtaining information related to dispersion on the frequency axis of interference signals for the terminal device, and if the dispersion of interference signals of the terminal device is equal to or higher than a specific level, packets different from transmission of retransmission packets with the terminal device Causing communication to avoid transmission of retransmission packets between the base station apparatus and the terminal apparatus;

Packet communication method.