WO2009098869A1

WO2009098869A1 - Radio communication base station device and channel allocation method

Info

Publication number: WO2009098869A1
Application number: PCT/JP2009/000425
Authority: WO
Inventors: Seigo Nakao; Masaru Fukuoka; Akihiko Nishio
Original assignee: Panasonic Corporation
Priority date: 2008-02-04
Filing date: 2009-02-04
Publication date: 2009-08-13

Abstract

It is possible to provide a radio communication base station device and a channel allocation method which can improve an uplink SDMA communication performance while reducing a scheduling load of a base station side which should consider the relationship between an uplink line data transmission logical resource and a downlink PHICH resource. An ACK/NACK channel allocation unit (109) decides a PHICH resource for which an ACK/NACK channel is to be allocated according to the following equation: PHICH number = Lowest VRB number + floor (CS number × number of allocated VRB/total number of CS) and allocates the ACK/NACK channel to the decidedPHICH resource.

Description

Radio communication base station apparatus and channel allocation method

The present invention relates to a radio communication base station apparatus and a channel allocation method.

In mobile communication, ARQ is performed on uplink data transmitted from a radio communication mobile station apparatus (hereinafter simply referred to as “mobile station”) to a radio communication base station apparatus (hereinafter simply referred to as “base station”) on the uplink. (Automatic Repeat Request) is applied, and a response signal indicating an error detection result of the uplink data is fed back to the mobile station on the downlink. The base station performs a CRC (Cyclic Redundancy Check) check on the uplink data, and if CRC = OK (no error), an ACK (Acknowledgment) signal is received. ) The signal is fed back to the mobile station as a response signal. These ACK / NACK signals are transmitted through a physical channel for downlink response signal transmission such as PHICH (Physical Hybrid-ARQ Indicator Channel).

Here, it is considered to apply synchronous HARQ (HybridRQARQ) to uplink data. In synchronous HARQ, the base station feeds back a response signal to a mobile station after elapse of a predetermined time after receiving uplink data. When the NACK signal is fed back from the base station, the mobile station receives the NACK signal. The uplink data is retransmitted to the base station after a predetermined time has elapsed.

Also, the base station transmits control information for notifying the allocation result of the logical resource block (Virtual Resource Block: VRB) number indicating the resource that the mobile station should use for uplink data transmission to the mobile station. This control information is transmitted to the mobile station using a downlink control channel such as PDCCH (Physical Downlink Control Channel). The PDCCH is configured by a physical resource unit called CCE (Control Channel Element), and each PDCCH occupies one or a plurality of CCEs. The base station configures the PDCCH according to the number of CCEs necessary for notifying the control information, assigns the control information to the physical resource corresponding to the CCE occupied by each PDCCH, and transmits the control information. When the mobile station receives control information, it transmits uplink data using a physical resource block (Physical Resource Block: PRB) corresponding to the VRB instructed there. For example, one physical resource block is formed of time / frequency resources having a size of 180 KHz on the frequency axis and 1 ms on the time axis.

On the other hand, in order to improve the utilization efficiency of uplink data transmission logical resources, a method in which multiple mobile stations simultaneously transmit each data using the same frequency resource and separate the signals on the base station side (Space Division Multiple Access : SDMA) is under consideration. In SDMA communication, processing on the spatial axis (for example, separation processing using a known adaptive array) is performed on the base station side, and signals from a plurality of mobile stations are spatially separated. ) There are a plurality of transmitting sides (mobile stations), each having an antenna. 2) The receiving side (base station) has a plurality of antennas and separates signals by spatial processing. Therefore, MIMO (Multiple-Input Multiple -Output) One form of communication is sometimes called MU-MIMO (Multi-user MIMO).

In order to spatially separate signals from a plurality of mobile stations by MU-MIMO communication on the base station side, highly accurate propagation path estimation is required on the base station side. Therefore, in general, in MU-MIMO communication, a reference signal (Demodulation Reference Signal: DM RS) used for propagation path estimation is a resource that is orthogonal in time, frequency, or code space to a plurality of mobile stations. A method is adopted in which the uplink transmission path estimation accuracy on the base station side is ensured, and the uplink data transmission logical resource (= physical resource) is shared only by the data portion.

For example, in 3GPP-LTE (see Non-Patent Document 1), when a plurality of mobile stations transmit signals simultaneously using the same frequency resource, that is, when performing MU-MIMO communication, a reference signal (DM RS) is code-multiplexed between a plurality of mobile stations.

That is, as shown in FIG. 1, a CAZAC (Constant-Amplitude-Zero-Auto-Correlation) sequence represented by the same ZC (Zadoff-Chu) sequence is allocated to a plurality of mobile stations performing MU-MIMO communication, and different mobile stations In between, a method of separating signals on the base station side by using CAZAC sequences having different cyclic shift (Cyclic Shift: CS) amounts on the time axis is applied. However, since the number of divisions on the time axis of the CAZAC sequence, that is, the definition number of different cyclic shift amounts is 8, here, a maximum of 8 mobile stations use the same frequency / time resource by code division multiplexing to perform DM. RS can be transmitted.

Here, the cross-correlation between CAZAC sequences having different cyclic shift amounts generated from the same CAZAC sequence is zero. Therefore, in an ideal communication environment, as shown in FIG. 1, a plurality of response signals spread and code-multiplexed by CAZAC sequences (cyclic shift amounts 0 to 7) having different cyclic shift amounts are transmitted at the base station. With this correlation processing, separation can be performed without intersymbol interference on the time axis.

Further, in synchronous HARQ, in order to efficiently use downlink resources, it is considered to associate a PHICH resource for transmitting a response signal on the downlink with a resource used for uplink data transmission (for example, Non-Patent Document 2 and Non-Patent Document 3). Accordingly, the mobile station can determine the PHICH resource addressed to itself from the resource allocation information for uplink data transmission notified by the PDCCH from the base station, even if the PHICH resource allocation information is not separately notified. it can.

However, when the above-described SDMA communication is used, since a plurality of mobile stations are allocated to the same uplink data transmission logical resource, contention for downlink PHICH resources occurs. Therefore, in

Non-Patent Documents

2 and 3, in order to avoid the contention of the downlink PHICH resource, the PHICH resource is defined by the VRB number assigned to the mobile station and the assigned cyclic shift (CS) number for DM 番号 RS.

In addition, when synchronous HARQ is applied to uplink data, since the data transmission timing is set in advance, it is 2 for mobile stations that transmit uplink data after the second transmission (retransmission) to the base station. PDCCH for resource allocation of uplink data after the second transmission (retransmission) is not transmitted. A response signal for uplink data after the second transmission (retransmission) is transmitted using the same PHICH resource as the PHICH resource used during the first transmission (initial transmission).
3GPP TS 36.211 V8.1.0, "Physical Channels and Modulation (Release 8)," Nov. 2007 3GPP RAN WG1 Meeting document, R1-073479, "Mapping Relations between UL VRB and DL ACK / NACK", LG Electronics, August 2007 3GPP RAN WG1 Meeting document, R1-080301, "PHICH and mapping to PHICH groups", Nokia, Nokia Siemens Networks, January 2008

In the above prior art, the downlink PHICH resource is determined using the VRB number assigned to the mobile station and the CS number of DM RS as described above. For example, in Non-Patent Document 1, as many PHICH resources as the number of VRBs used for uplink data transmission are prepared and defined as follows.

PHICH number = Lowest VRB number + (CS number mod number of allocated VRBs) (1)
However, the lowest VRB number indicates the index number of the VRB having the smallest index among a plurality of consecutive VRBs allocated for uplink data transmission of the mobile station, and the allocated VRB number is for the mobile station. Indicates the number of allocated VRBs. Assuming that the total number of VRBs in the system is 20, the total number of PHICH resources is 20, and the number of CSs is 8, the correspondence between VRB numbers and CS numbers using this method is as shown in FIG.

When performing multi-frequency 2 SDMA communication using the method disclosed in Non-Patent Document 1, the operation of the base station is as follows, for example. Since at least two PHICH resources need to be reserved for SDMA communication with 2 multiplexing, the base station allocates two VRBs (for example, VRB2-3) for 2-multiplex SDMA communication. In this case, since the two PHICH resources corresponding to the two VRBs do not compete with other mobile stations, two PHICH resources (PHICH2-3) can be secured for two-multiplexed SDMA communication.

Next, the base station assigns an appropriate DM RS CS number to each mobile station in order to avoid contention of PHICH resources between two mobile stations performing SDMA communication. Referring to Equation (1) and FIG. 2, mobile stations assigned to VRB 2-3 and assigned

CS numbers

0, 2, 4, 6 and

CS numbers

1, 3, 5, and 7 are assigned. For example, the base station assigns CS number 1 to one mobile station and assigns CS number 2 to the other.

When the base station performs 4-multiplex SDMA communication, 4 VRBs (for example, VRB 12-15) are allocated to 4 mobile stations. Referring to Equation (1) and FIG. 2, mobile stations assigned to VRB 12-15 and assigned

CS numbers

0 and 4, CSs assigned

CS numbers

1 and 5, CS numbers 2, Since the PHICH resources of the mobile stations to which 6 is assigned and the mobile stations to which

CS numbers

3 and 7 are assigned compete, for example, the base station assigns

CS numbers

0, 2, 5 to 4 mobile stations, respectively. , 7 resources are allocated.

The CS number is applied to DM RS used for propagation path estimation between each mobile station and the base station on the base station side. As described above, in an ideal communication environment, CAZAC sequences corresponding to different CS numbers are Since they are orthogonal to each other, signals can be separated on the base station side without intersymbol interference.

However, a plurality of DM タイミング RSs from a plurality of mobile stations do not always reach the base station at the same time due to transmission timing shifts at the mobile station, delayed waves due to multipath, frequency offset, and the like. For example, as shown in FIG. 3A, when the transmission timing of a DM-RS spread with a CAZAC sequence with a cyclic shift amount of 0 is delayed from the correct transmission timing, the correlation peak of the CAZAC sequence with a cyclic shift amount of 0 indicates that the cyclic shift amount is 1. Appear in the detection window of the CAZAC sequence. Further, as shown in FIG. 3B, when there is a delayed wave in DM RS spread by a CAZAC sequence with a cyclic shift amount of 0, interference leakage due to the delayed wave appears in the detection window of the CAZAC sequence with a cyclic shift amount of 1 End up. In these cases, a CAZAC sequence with a cyclic shift amount of 1 receives interference from a CAZAC sequence with a cyclic shift amount of 0. Therefore, in these cases, the separation characteristics of DM RS spread with a CAZAC sequence with a cyclic shift amount of 0 and DM RS spread with a CAZAC sequence with a cyclic shift amount of 1 deteriorate, and uplink propagation from each mobile station The path estimation cannot be performed correctly. That is, if CAZAC sequences having cyclic shift amounts adjacent to each other are used, there is a possibility that the separation characteristics of DM RS transmitted using the same VRB may be deteriorated. In other words, in SDMA, it is necessary to assign CS numbers that are as far away as possible to different mobile stations.

By the way, as described above, in the method shown in Non-Patent Document 1, a mobile station to which the same VRB is assigned by SDMA and a mobile station to which CS numbers (for example, 0 and 4) that are separated as far as possible are assigned. There is a problem in that the SDMA performance deteriorates due to competing PHICH resources.

On the other hand, Non-Patent Document 2 prepares PHICH resources by the same number as the number of VRBs used for uplink data transmission, and defines them as the following equation.

PHICH number = (Lowest VRB number + CS number) mod Total number of PHICH resources ... (2)

In this case, assuming that the total number of VRBs is 20, the total number of PHICH resources is 20, and the number of CSs is 8, the correspondence between VRB numbers and CS numbers and PHICH numbers using this method is as shown in FIG.

When performing SDMA communication with a multiplicity of 2 using the method disclosed in Non-Patent Document 2, it is possible to assign CS numbers as far as possible to a plurality of mobile stations performing SDMA communication. The operation of the base station at this time is as follows, for example. The base station allocates two VRBs (for example, VRB2-3) for 2-multiplex SDMA communication, and assigns different CS amounts 0 and 4 to each mobile station. Referring to Equation (2) and FIG. 4, the PHICH resource number corresponding to the mobile station to which VRB2-3 and CS amount 0 are assigned is 2, and the PHICH corresponding to the mobile station to which VRB2-3 and CS amount 4 is assigned. Since the resource number is 6, the PHICH resource does not compete. That is, contention of PHICH resources can be avoided while suppressing mutual interference between DM 間の RSs of two SDMA mobile stations.

However, since the PHICH resource 6 is used for the mobile station in the SDMA communication, when the CS number 0 is assigned to the non-SDMA mobile station to which the VRB number 6 is assigned, a PHICH resource contention occurs. That is, it is necessary to assign a CS number other than CS number 0 for a mobile station to which VRB number 6 is assigned. Further, when a non-SDMA terminal to which VRB number 6 is assigned uses resources other than PHICH number 6, the effect is spread to all mobile stations communicating with the base station.

In general, SDMA communication is applicable only to some mobile stations having a good propagation environment and low cross-correlation of propagation paths, and some mobile stations performing SDMA communication may be other mobile stations. It is not preferable to limit the arrangement of VRB numbers and CS numbers. Further, in this case, the load on scheduling on the base station side becomes very large.

An object of the present invention is to provide a radio communication base station apparatus and channel allocation that improve the performance of uplink SDMA communication while reducing the scheduling load on the base station side that should consider the relationship between the logical resource for uplink data transmission and the downlink PHICH resource Is to provide a method.

The radio communication base station apparatus of the present invention assigns PHICH resources to which ACK / NACK channels are allocated to PHICH number = Lowest VRB number + floor (CS number × number of allocated VRBs / total number of CSs).
However, the Lowest VRB number indicates the index number of the VRB having the smallest index among a plurality of continuous virtual resource blocks (VRBs) allocated for uplink data transmission of the radio communication mobile station apparatus, and the number of allocated VRBs. Indicates the number of VRBs allocated for the radio communication mobile station apparatus, the CS number indicates the cyclic shift amount of the code sequence used for the uplink reference signal, and the total CS number indicates the code sequence that can be used for the reference signal Indicates the total number of cyclic shifts.
The ACK / NACK channel allocating unit that allocates the ACK / NACK channel to the obtained PHICH resource and the transmission unit that transmits the ACK / NACK channel allocated to the PHICH resource are employed.

In the channel allocation method of the present invention, a PHICH resource for allocating an ACK / NACK channel is defined as PHICH number = Lowest VRB number + floor (CS number × number of allocated VRBs / total number of CSs).
However, the Lowest VRB number indicates the index number of the VRB having the smallest index among a plurality of consecutive virtual resource blocks (VRBs) allocated for uplink data transmission of the radio communication mobile station apparatus, and the number of allocated VRBs. Indicates the number of VRBs allocated for the radio communication mobile station apparatus, the CS number indicates the cyclic shift amount of the code sequence used for the uplink reference signal, and the total CS number indicates the code sequence that can be used for the reference signal Indicates the total number of cyclic shifts.
And an ACK / NACK channel assignment step for assigning an ACK / NACK channel to the obtained PHICH resource, and a transmission step for transmitting the ACK / NACK channel assigned to the PHICH resource.

According to the present invention, it is possible to improve the performance of uplink SDMA communication while reducing the scheduling load on the base station side that should consider the relationship between the uplink data transmission logical resource and the downlink PHICH resource.

Diagram for explaining CAZAC series Schematic diagram showing the correspondence between VRB, CS and PHICH disclosed in Non-Patent Document 1. The figure which shows the correlation process of the ACK / NACK signal spread | diffused by the CAZAC series (when there exists a shift | offset | difference of transmission timing) The figure which shows the correlation process of the ACK / NACK signal spread by the CAZAC sequence (when there is a delay wave) Schematic diagram showing the correspondence between VRB, CS and PHICH disclosed in Non-Patent Document 2 The block diagram which shows the structure of the base station which concerns on Embodiment 1 of this invention. Schematic diagram showing the correspondence between VRB, CS and PHICH according to the first embodiment of the present invention Schematic diagram showing the correspondence between VRB, CS and PHICH according to Embodiment 2 of the present invention

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

(Embodiment 1)
FIG. 5 shows the configuration of base station 100 according to Embodiment 1 of the present invention.

In base station 100 shown in FIG. 5, radio receiving section 102 receives uplink data transmitted from each mobile station via antenna 101, and receives down-converting, A / D conversion, etc. for this uplink data. Process. The received uplink data is output to demodulation section 103.

Demodulation section 103 demodulates the uplink data output from radio reception section 102 and outputs the demodulated uplink data to decoding section 104.

The decoding unit 104 decodes the uplink data output from the demodulation unit 103 and outputs the decoded uplink data to the error detection unit 105.

The error detection unit 105 performs error detection using CRC determination on the uplink data output from the decoding unit 104, and when CRC = OK (no error), an ACK signal and CRC = NG (with error) ), A NACK signal is generated as a response signal, and the generated response signal is output to modulation section 106. In addition, when CRC = OK (no error), error detection section 105 outputs decoded uplink data as received data.

Modulation section 106 modulates the response signal of each mobile station output from error detection section 105, and outputs the modulated response signal to ACK / NACK channel allocation section 109.

The PDCCH allocation unit 107 receives uplink allocation information # 1 to #K indicating which uplink resource is allocated to which mobile station for a maximum of K mobile stations # 1 to #K. PDCCH allocation section 107 allocates input uplink allocation information # 1 to #K to any one of PDCCH # 1 to #K. Each PDCCH is composed of one or a plurality of CCEs among CCEs # 1 to #M. PDCCH allocating section 107 then outputs the data to encoding / modulating sections 108-1 to 108-K corresponding to the PDCCH allocated with uplink allocation information # 1 to #K, respectively. Also, the PDCCH allocating unit 107 transmits resource allocation information indicating which uplink data transmission logical resource (VRB) and CS number used for the DM RS are allocated to each mobile station. The ACK / NACK channel allocating unit 109 Output to.

Encoding / modulating sections 108-1 to 108-K are provided corresponding to PDCCH # 1 to #K, and include an encoding section 1081 and a modulation section 1082. In encoding / modulating sections 108-1 to 108-K, encoding section 1081 encodes uplink allocation information output from PDCCH allocation section 107 and outputs the encoded information to modulation section 1082, and modulation section 1082 performs encoding. The uplink allocation information output from section 1081 is modulated to generate an uplink allocation information symbol and output to allocation section 110.

The ACK / NACK channel allocation unit 109 allocates the response signal output from the modulation unit 106 to the PHICH resource based on the resource allocation information output from the PDCCH allocation unit 107. Specifically, the ACK / NACK channel allocation unit 109 sends a response signal for each mobile station to the uplink data transmission logical resource allocated to each mobile station, the number of allocated logical resource blocks, and DM. Assign to the PHICH resource associated with the CS number used for the RS. Here, when a plurality of VRBs are allocated to one mobile station, the ACK / NACK channel allocation unit 109 has the VRB with the smallest VRB number among the allocated VRBs, the number of allocated VRBs, and DM RS. A response signal is allocated to the PHICH resource associated with the CS number used for the. Then, ACK / NACK channel assignment section 109 outputs a response signal assigned to the PHICH resource to placement section 110. Details of the PHICH resource allocation processing in the ACK / NACK channel allocation unit 109 will be described later.

Arrangement section 110 arranges the PDCCH output from encoding / modulation sections 108-1 to 108-K and allocated with uplink allocation information symbols in downlink resources reserved in PDCCH, and provides an ACK / NACK channel allocation section. The PHICH resource output from 109 and assigned with the response signal is arranged in the downlink physical resource reserved for PHICH. Arrangement section 110 outputs a signal in which each channel is arranged to radio transmission section 111.

The radio transmission unit 111 performs transmission processing such as D / A conversion, amplification, and up-conversion on the signal output from the arrangement unit 110 and transmits the signal from the antenna 101 to each mobile station.

On the other hand, when each mobile station receives a PDCCH addressed to itself from the base station 100, the mobile station transmits transmission data to the base station 100 according to uplink allocation information and MCS (Modulation and Coding Scheme). Each mobile station also receives a response signal assigned to the PHICH resource associated with the VRB number, the number of VRBs, and the CS number assigned to the mobile station. Here, in each mobile station, it is assumed that which PHICH resource corresponds to which downlink physical resource is instructed by an upper layer or is defined in advance. Then, when the response signal is an ACK signal, each mobile station waits until a PDCCH addressed to itself is transmitted from the base station 100 in order to transmit the next transmission data. On the other hand, each mobile station retransmits transmission data when the response signal is a NACK signal.

Next, details of the PHICH resource allocation process in the ACK / NACK channel allocation unit 109 will be described. Here, as shown in the upper part of FIG. 6, 20 VRBs # 0 to # 19 are defined as logical resources for uplink data transmission. Further, the uplink data transmission logical resource allocated to each mobile station is composed of one VRB or a plurality of VRBs adjacent to each other among 20 VRBs. Further, CS # 0 to CS # 7 are defined as CS numbers that the mobile station should use in the uplink propagation path estimation reference signal (DM RS), and one CS number is associated with one mobile station. That is, the mobile station is instructed from the base station 100 by a plurality of VRB numbers to which uplink data should be transmitted and the CS number. For example, as shown in the upper part of FIG. 6, VRBs # 0 to # 1 are allocated as data resources for mobile stations that occupy 1 VRB, and VRBs # 2 to # 5 are allocated as data resources for mobile stations that occupy 2 VRBs. VRBs # 6 to # 11 are allocated as data resources for mobile stations occupying 3VRB, and VRBs # 12 to # 19 are allocated as data resources for mobile stations occupying 4VRB.

Also, as shown in the lower part of FIG. 6, base station 100 reserves in advance downlink physical resources for arranging a maximum of 20 PHICH resources # 0 to # 19 corresponding to 20 VRBs # 0 to # 19, respectively. . However, as shown in FIG. 6, the PHICH resource number is defined in association with both the VRB number and the CS number. That is, the relationship between the PHICH number, the VRB number, and the CS number is as follows.

PHICH number = Lowest VRB number + floor (CS number × number of assigned VRBs / total number of CSs) (3)
However, in Expression (3), floor (X) indicates the maximum integer not exceeding X, and the total number of CS is 8 (CS # 0 to CS # 7).

As shown in FIG. 6 and equation (3), since a mobile station to which one VRB # 0 is allocated is associated with PHICH # 0 regardless of the CS number, the ACK / NACK channel allocation unit 109 assigns a response signal to the uplink data assigned to VRB # 0 to PHICH # 0. Also, as shown in FIG. 6 and Equation (3), PHICH # 2 is associated with mobile stations to which VRB # 2 to # 3 are assigned and CS numbers # 0 to # 3 are assigned. Therefore, ACK / NACK channel assignment section 109 assigns a response signal for uplink data to which VRB # 2 to # 3 and CS numbers # 0 to # 3 are assigned to PHICH # 2. Also, since PHICH # 3 is associated with mobile stations to which VRBs # 2 to # 3 are assigned and CS numbers # 4 to # 7 are assigned, ACK / NACK channel assignment unit 109 Assigns response signals for uplink data to which VRB # 2 to # 3 and CS numbers # 4 to # 7 are assigned to PHICH # 3.

Also, since PHICH # 12 is associated with mobile stations to which VRBs # 12 to # 15 are assigned and CS numbers # 0 to # 1 are assigned, ACK / NACK channel assignment unit 109 Assigns response signals for uplink data to which VRB # 12 to # 15 and CS numbers # 0 to # 1 are assigned to PHICH # 12. Mobile stations to which VRB # 12 to # 15 are assigned and CS numbers # 2 to # 3 are assigned, and mobile stations to which VRB # 12 to # 15 are assigned and CS numbers # 4 to # 5 are assigned The same applies to mobile stations to which stations, VRB # 12 to # 15 and CS numbers # 6 to # 7 are assigned.

That is, the operations related to scheduling of the base station 100 are summarized as follows. When the mobile station is not the target of SDMA communication, scheduling on the frequency axis is performed to determine the frequency resource. At this time, since the same VRB is not assigned to another mobile station in the same cell, the best CS number is assigned to the mobile station in terms of performance without worrying about PHICH resource contention. For example, when the base station 100 has information on a plurality of sectors (cells), by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resources in adjacent sectors. Inter-cell interference can be reduced.

In addition, when the mobile station is a target of 2-multiplex SDMA communication, the base station 100 performs frequency scheduling on the premise that continuous VRBs equal to or more than the SDMA multiplicity are allocated for 2-multiplex SDMA communication (for example, VRB2-3 is set). assign). In this case, since the two PHICH resources corresponding to the two VRBs do not compete with other mobile stations in the same cell, two PHICH resources (PHICH2-3) can be secured for two-multiplex SDMA communication.

Next, in the base station 100, in order to avoid mutual interference between DM RSs of two mobile stations that perform SDMA communication, CS numbers (

CS numbers

0 and 4, 1 and 5) that are as far away as possible from the two mobile stations are separated. 2 and 6 or 3 and 7). In this case, referring to Equation (3) and FIG. 6, PHICH resources corresponding to the two mobile stations do not compete with each other. In addition, when the base station 100 has information on a plurality of sectors, by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resource in adjacent sectors, Interference can be reduced.

When the mobile station is a target of 4-multiplex SDMA communication, the base station 100 performs frequency scheduling on the assumption that continuous VRBs equal to or greater than the SDMA multiplicity are allocated for 4-multiplex SDMA communication (for example, VRB 12-15 is set). assign). In this case, since the four PHICH resources corresponding to the four VRBs do not compete with other mobile stations, four PHICH resources (PHICH12-15) can be secured for the 4-multiplex SDMA communication. In base station 100, in order to avoid mutual interference between DM RSs of four mobile stations that perform SDMA communication, CS numbers (sets of

CS numbers

0, 2, 4, and 6) that are as far apart as possible from the four mobile stations are separated. Or a set of 1, 3, 5, and 7). Again, referring to Equation (3) and FIG. 6, PHICH resources corresponding to the four mobile stations do not compete with each other. In addition, when the base station 100 has information on a plurality of sectors, by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resource in adjacent sectors, Interference can be reduced.

As described above, according to Embodiment 1, there is no explicit signaling (Signaling) regarding the downlink PHICH resource, and even if the CS number is freely assigned to a mobile station other than the SDMA communication target, the downlink PHICH resource Contention does not occur, and mobile stations subject to SDMA communication are assigned VRBs equal to or greater than the multiplicity and CS numbers that maximize the SDMA reception performance on the base station side. Conflicts can be avoided. That is, the base station 100 side has only a simple scheduling function, and VRB and CS number arrangements that are optimal in terms of performance are possible. Therefore, according to the present embodiment, it is possible to improve the performance of uplink SDMA communication while reducing the scheduling load.

In addition to the mobile stations subject to SDMA communication, CS numbers can be freely assigned while taking into account other cell interference and the like. Since it is possible to assign a CS number that takes cell interference into consideration to some extent, system throughput can be improved.

In this embodiment, when there are a plurality of uplink data transmission VRBs assigned to mobile stations that are not subject to SDMA communication, the VRB having the smallest number among the assigned VRBs and the assigned VRBs. Although the PHICH resource associated with the number and the CS number is used, the VRB having the largest number among the assigned VRBs, the number of assigned VRBs, and the PHICH resource associated with the CS number may be used. In this case, Equation (3) is modified as follows.

PHICH number = Highest VRB number−floor (CS number × number of allocated VRBs / total number of CSs) (4)
However, the Highest VRB number indicates the index number of the VRB having the largest index among a plurality of consecutive VRBs allocated for uplink data transmission of the mobile station.

(Embodiment 2)
In Embodiment 2 of the present invention, one PHICH resource is associated with a plurality of uplink data transmission VRBs to reduce PHICH resources. Specifically, N VRBs prepared in the system are grouped by M to form a total of N / M VRB groups. In addition, one PHICH resource is associated with one VRB group. In this case, FIG. 6 and Formula (3) are transformed into FIG. 7 and Formula (5).

PHICH number = Lowest VRB group number + floor (CS number × number of assigned VRB groups / total number of CS) (5)
However, in FIG. 7, the number of VRBs per group is 2 (M = 2). Furthermore, Formula (5) can be modified as follows using M.

PHICH number = Lowest VRB number / M + floor (CS number × number of allocated VRB groups / (total number of CS × M)) (6)
In this case, base station 100 allocates uplink data transmission logical resources to each mobile station in units of VRB groups.

The scheduling operation of the base station 100 in the second embodiment is summarized as follows. When the mobile station is not the target of SDMA communication, scheduling on the frequency axis is performed to determine the frequency resource. At this time, since the same VRB group is not assigned to another mobile station in the same cell, the PHICH resource does not compete, and the best CS number is assigned to the mobile station in terms of performance. For example, when the base station 100 has information on a plurality of sectors (cells), by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resources in adjacent sectors. Inter-cell interference can be reduced.

Also, when the mobile station is a target of 2-multiplex SDMA communication, the base station 100 performs frequency scheduling on the assumption that continuous VRB groups equal to or more than the SDMA multiplicity are allocated for 2-multiplex SDMA communication (for example, VRB group 1 -2). In this case, since the two PHICH resources corresponding to the two VRB groups do not compete with other mobile stations in the same cell, two PHICH resources (PHICH1-2) can be secured for two-multiplex SDMA communication. .

CS numbers

0 and 4, 1 and 5) that are as far away as possible from the two mobile stations are separated. 2 and 6 or 3 and 7). In this case, referring to Equation (5) and FIG. 7, PHICH resources corresponding to the two mobile stations do not compete with each other. In addition, when the base station 100 has information on a plurality of sectors, by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resource in adjacent sectors, Interference can be reduced.

Further, when the mobile station is a target of 4-multiplex SDMA communication, the base station 100 performs frequency scheduling on the premise that continuous VRB groups equal to or more than the SDMA multiplicity are allocated for 4-multiplex SDMA communication (for example, VRB group 6 -9 is assigned). In this case, since the four PHICH resources corresponding to the four VRB groups do not compete with other mobile stations, four PHICH resources (PHICH 6-9) can be secured for the 4-multiplex SDMA communication. In the base station 100, in order to avoid mutual interference between DM RSs of four mobile stations that perform SDMA communication, CS numbers (

CS numbers

0, 2, 4, 6, or 1) that are as far away as possible from the four mobile stations are separated. , 3, 5, 7). Again, referring to equation (7) and FIG. 7, PHICH resources corresponding to the four mobile stations do not compete with each other. In addition, when the base station 100 has information on a plurality of sectors, by using a CS number different from the CS number for DM RS assigned to other mobile stations using the same time / frequency resource in adjacent sectors, Interference can be reduced.

As described above, according to the second embodiment, there is no explicit signaling related to the downlink PHICH resource, and contention of the downlink PHICH resource occurs even if a CS number is freely assigned to a mobile station other than the SDMA communication target mobile station. In addition, the mobile station subject to SDMA communication is assigned with VRB groups equal to or more than the multiplicity and a CS number that maximizes the SDMA reception performance on the base station side, thereby avoiding contention for downlink PHICH resources. be able to. That is, the VRB group and the CS number arrangement that are optimal in terms of performance can be achieved only by providing a simple scheduling function on the base station side. Therefore, according to the present embodiment, it is possible to improve the performance of uplink SDMA communication while reducing the scheduling load.

The embodiment of the present invention has been described above.

In the above embodiment, a logical resource is assigned to a mobile station, and the mobile station converts it to a physical resource. However, the base station assigns a physical resource block block number directly to the mobile station. Also good. In this case, the PHICH resource is associated with a physical resource block (PRB) number, an assigned PRB number, and a CS number. The physical resource block may be simply referred to as a resource block (Resource Block: RB).

In the above embodiment, the logical resource block or physical resource block allocated to the mobile station and the CS number do not change during communication. However, in order to obtain the diversity effect of uplink communication, the resource block and CS When the number hops (changes the logical resource / physical resource and CS number on the time axis), for example, the logical resource block or physical resource block number used in the first slot and the number of allocated resource blocks and The PHICH resource may be associated with the CS number.

In the above embodiment, the CS numbers are sequentially associated with the physical cyclic shift amounts. However, the correspondence between the physical cyclic shift amount and the CS number indicated by the base station is not related to this. It is not limited to. For example, CS number 0 may indicate a physical cyclic shift amount 0, and CS number 1 may indicate a physical cyclic shift amount 4. In this case, the PHICH resource is associated with the logical resource block number or physical resource block number and the number of allocated resource blocks, and the physical cyclic shift amount. In short, in SDMA communication, when a CS number whose physical cyclic shift amount is as far as possible is assigned to DM RS transmitted by each mobile station, PHICH resources may not compete.

In the above embodiment, eight cyclic shift amounts used for DM RS are defined at equal intervals. For example, twelve cyclic shift amounts are defined, and eight cyclic shift amounts are defined as bases. You may associate with CS number which a station instruct | indicates in order. Even in this case, since the physical cyclic shift amount greatly varies as the CS number increases, the same effect can be obtained even if the present embodiment is applied as it is. Further, when the order of correspondence between the physical cyclic shift amount and the CS number is different, the PHICH resource is associated with the logical resource block number or the physical resource block number and the number of allocated resource blocks, and the physical cyclic shift amount. become.

In the above embodiment, the case of transmitting a response signal of uplink data has been described. However, the present invention can also be applied to a response signal of downlink data. For example, the present invention can be applied to a downlink data response signal by the mobile station performing the same processing as the base station 100. However, the base station 100 assigns downlink resources. That is, the mobile station does not perform the same processing as the PDCCH allocation unit 107 in the base station 100. Therefore, the mobile station transmits a response signal using the ACK / NACK channel associated with the VRB used for downlink data, the number of assigned VRBs, and the CS number.

Also, the PDCCH used in the description of the above embodiment may be referred to as SCCH (Shared Control Channel), L1 / L2 Control Channel, UL grant channel, and CCCH (Common Control Channel). Also, the PHICH resource may be referred to as a HICH (Hybrid ARQ Indicator Channel) resource or an ACK / NACK resource.

Also, the mobile station may be referred to as UE (User Equipment), and the base station may be referred to as Node B.

Also, the error detection method is not limited to CRC determination.

Further, although cases have been described with the above embodiment as examples where the present invention is configured by hardware, the present invention can also be realized by software.

Further, each functional block used in the description of the above 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 so as to include a part or all of them. The name used here is LSI, but it may also be called IC, system LSI, super LSI, or ultra LSI depending on the degree of integration.

Further, the method of circuit integration is not limited to LSI, and implementation with a dedicated circuit or a general-purpose processor is also possible. An FPGA (Field Programmable Gate Array) that can be programmed after manufacturing the LSI or a reconfigurable processor that can reconfigure the connection and setting of circuit cells inside the LSI may be used.

Furthermore, if integrated circuit technology that replaces LSI emerges as a result of advances in semiconductor technology or other derived technology, it is naturally also possible to integrate functional blocks using this technology. Biotechnology can be applied.

The disclosure of the specification, drawings and abstract contained in the Japanese application of Japanese Patent Application No. 2008-024437 filed on Feb. 4, 2008 is incorporated herein by reference.

The radio communication base station apparatus and channel allocation method according to the present invention improve the performance of uplink SDMA communication while reducing the scheduling load on the base station side that should consider the relationship between the uplink data transmission logical resource and the downlink PHICH resource. For example, it can be applied to a mobile communication system.

Claims

PHICH resource to which ACK / NACK channel is allocated PHICH number = Lowest VRB number + floor (CS number × number of allocated VRBs / total number of CSs)
However, the Lowest VRB number indicates the index number of the VRB having the smallest index among a plurality of consecutive virtual resource blocks (VRBs) allocated for uplink data transmission of the radio communication mobile station apparatus, and the number of allocated VRBs. Indicates the number of VRBs allocated for the radio communication mobile station apparatus, the CS number indicates the cyclic shift amount of the code sequence used for the uplink reference signal, and the total CS number indicates the code sequence that can be used for the reference signal Indicates the total number of cyclic shifts.
ACK / NACK channel assignment means for assigning an ACK / NACK channel to the obtained PHICH resource,
Transmitting means for transmitting an ACK / NACK channel allocated to the PHICH resource;
A wireless communication base station apparatus comprising:
The radio communication base station apparatus according to claim 1, wherein the ACK / NACK channel allocation means obtains a PHICH resource by grouping a plurality of VRBs.
PHICH resource to which ACK / NACK channel is allocated PHICH number = Lowest VRB number + floor (CS number × number of allocated VRBs / total number of CSs)
However, the Lowest VRB number indicates the index number of the VRB having the smallest index among a plurality of consecutive virtual resource blocks (VRBs) allocated for uplink data transmission of the radio communication mobile station apparatus, and the number of allocated VRBs. Indicates the number of VRBs allocated for the radio communication mobile station apparatus, the CS number indicates the cyclic shift amount of the code sequence used for the uplink reference signal, and the total CS number indicates the code sequence that can be used for the reference signal Indicates the total number of cyclic shifts.
ACK / NACK channel assignment step for assigning an ACK / NACK channel to the obtained PHICH resource,
A transmission step of transmitting an ACK / NACK channel allocated to the PHICH resource;
A channel allocation method comprising: