JP2010206403A - Base station, terminal and radio communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base station, a terminal and a radio communication system, capable of controlling the transmission weight of an MIMO transmission system, without having to execute frequent CQI reporting for each stream. <P>SOLUTION: The base station for MIMO-transmitting K (K is an integer≥2) pieces of streams to the terminal by using a plurality of antennas includes: a control information generation means for generating first to K-th control information specifying physical resources to use in the transmission of first to K-th streams including data respectively; a control information transmission means for transmitting the first to K-th control information to the terminal; a detection means for detecting the first physical resource which is the physical resource specified in the k1-th control information (k1 is one of the values of 1 to K) and which is not specified in the k2-th control information (k2 is one of the values of 1 to K, which is different from k1); and a signal transmission means for transmitting the k2-th stream, including quality measurement signals for measuring the channel quality of the first physical resource in the terminal by using the first physical resource. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a base station, a terminal, and a wireless communication system in which a MIMO (Multiple Input Multiple Output) scheme is applied to FM-MODE of the next generation PHS (Personal Handyphone System), for example.

  In the next-generation PHS standard, the terminal uses the SINR (Signal to Interference and Noise Ratio) for the allocated physical resources among the 72 physical resources as a means to transmit the state of the physical resources to the base station. As a physical resource, a method for measuring RSSI (Received Signal Strength Indicator) and transmitting a CQI (Channel Quality Indicator) report including these measured values to the base station is defined (ARIB standard STD-T95).

ARIB Standard STD-T95 “OFDMA / TDMA TDD Broadband Wireless Access System (Next Generation PHS) ARIB STANDARD”, 1.0

  Assuming that the above-mentioned method defined in the next-generation PHS standard is extended to the MIMO transmission method, a CQI report is required for each stream. Therefore, the base station selects a transmission weight for each stream. When the CQI report is used, there is a problem that the amount of CQI report from the terminal is increased and the frequency is increased, and the amount of feedback information necessary for the MIMO transmission method is increased.

  The present invention provides a base station, a terminal, and a wireless communication system capable of performing transmission weight control of the MIMO transmission scheme in the next generation PHS without performing frequent CQI reports for each stream.

The base station as one aspect of the present invention is:
A base station for transmitting K (K is an integer of 2 or more) streams to a terminal using a plurality of antennas, and MIMO (Multiple Input Multiple Output) transmission.
Control information generating means for generating first to Kth control information designating physical resources used for transmission of the first to Kth streams each including data;
Control information transmitting means for transmitting the first to Kth control information to the terminal;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Detection means for detecting physical resources;
Signal transmitting means for transmitting, using the first physical resource, the k2 stream including a quality measurement signal for measuring the channel quality of the first physical resource at the terminal;
It is provided with.

The terminal as one aspect of the present invention is:
A terminal that receives first to Kth (K is an integer of 2 or more) streams transmitted from a base station via MIMO (Multiple Input Multiple Output) using a plurality of antennas,
Control information receiving means for receiving, from the base station, first to K-th control information specifying physical resources used for transmitting the first to K-th streams each including data;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Detection means for detecting physical resources;
Data receiving means for receiving the data of the first to Kth streams via the physical resource specified by the first to Kth control information;
Data demodulating means for demodulating each of the data;
A delivery confirmation generating means for generating delivery confirmation information for each of the data based on whether each of the data is correctly demodulated;
CQI information generating means for measuring the quality measurement signal of the k2th stream transmitted from the base station via the first physical resource and generating CQI information representing the channel quality of the first physical resource;
Feedback transmission means for transmitting feedback information including the delivery confirmation information of each data of the first to Kth streams and the CQI information of the first physical resource to the base station;
It is provided with.

A wireless communication system as one aspect of the present invention includes:
A wireless communication system that performs MIMO (Multiple Input Multiple Output) transmission of first to Kth streams (K is an integer of 2 or more) from a base station to a terminal using a plurality of antennas,
The base station
Control information generating means for generating first to Kth control information designating physical resources used for transmission of the first to Kth streams each including data;
Control information transmitting means for transmitting the first to Kth control information to the terminal;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Base station detection means for detecting physical resources;
Signal transmitting means for transmitting, using the first physical resource, the k2 stream including a quality measurement signal for measuring the channel quality of the first physical resource at the terminal;
Data transmitting means for transmitting the first to Kth streams including the data using physical resources specified by the first to Kth control information,
The terminal
Control information receiving means for receiving the first to Kth control information from the base station;
Terminal detection means for detecting the first physical resource based on the first to Kth control information;
Data receiving means for receiving the data of the first to Kth streams via the physical resource specified by the first to Kth control information;
Demodulation means for demodulating each of the data;
A delivery confirmation generating means for generating delivery confirmation information for each of the data based on whether each of the data is correctly demodulated;
CQI information generating means for measuring the quality measurement signal of the k2 stream transmitted from the base station via the first physical resource and generating CQI information representing the channel quality of the first physical resource;
Feedback transmission means for transmitting feedback information including the delivery confirmation information of each data of the first to Kth streams and the CQI information of the first physical resource to the base station;
It is provided with.

  According to the present invention, it is possible to perform transmission weight control of the MIMO transmission scheme in the next generation PHS without performing frequent CQI reports for each stream.

The figure which shows the radio | wireless communications system comprised from the base station and terminal by this Embodiment. The figure which shows the frame structure of next-generation PHS. The figure which shows the structural example of the next-generation PHS base station to which the MIMO transmission system by this Embodiment is applied. The figure which shows the physical frame format of DL-ANCH of the next generation PHS which applied the MIMO transmission system by this Embodiment. The figure which shows the structural example of DL-EDCH of the next generation PHS which applied the MIMO transmission system by this Embodiment, and the 1st structural example of CRCH. The figure which shows the 2nd structural example of CRCH by this Embodiment. The figure which shows the structural example of the next-generation PHS terminal to which the MIMO transmission system by this Embodiment is applied. The figure which shows the 1st structural example of the physical frame format and ACK field of UL-ANCH of the next generation PHS to which the MIMO transmission system by this Embodiment is applied. The figure which shows the 2nd structural example of the ACK field by this Embodiment. The figure which shows the communication path between the antenna of a base station and a terminal by this Embodiment, and a transmission weight.

  In the present embodiment, data transmission of a stream is performed in a next-generation PHS (Personal Handyphone System) wireless communication system to which MIMO (Multiple-Input Multiple-Output) transmission technology that spatially multiplex-transmits a plurality of streams is applied. Sends another stream including a quality measurement signal using a physical resource (first physical resource) that is used and not used for data transmission of another stream, and returns ACK information defined in the next-generation PHS standard By feeding back CQI (Channel Quality Indicator) information indicating the measurement quality of the physical resource using the field for transmission, transmission weight control for each stream can be performed with a small feedback amount without performing frequent CQI reports for each stream. Is to achieve.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a wireless communication system according to the present embodiment.

  This wireless communication system includes a base station 11 and a terminal 101. The base station 11 includes a plurality of antennas 1 to M, and the terminal 101 includes a plurality of antennas 1 to N. The base station 11 spatially multiplexes K (K is an integer of 2 or more) streams using a plurality of antennas by a MIMO (Multiple-Input Multiple-Output) transmission method, and transmits the streams to the terminal 11. Receives K streams transmitted from the base station 11 by the MIMO transmission scheme using a plurality of antennas. In addition, the terminal 101 spatially multiplexes and transmits S (S is an integer of 1 or more) streams to the base station 11 using a plurality of antennas according to the MIMO transmission scheme, and the base station 11 uses a plurality of antennas. S streams transmitted from the terminal 101 by the MIMO transmission method are received. However, the present invention can be applied to uplink transmission from the terminal 101 to the base station 11 with or without applying the MIMO transmission scheme.

  In particular, the present embodiment relates to the MIMO transmission system in the downlink from the base station 11 to the terminal 101 in the FM-Mode of the next generation PHS, and thereafter, based on the next generation PHS standard. Give an explanation. Further, the application range of the present invention is not limited to the next generation PHS, but unless otherwise specified, the operations of the base station 11 and the terminal 102 will be described as following the next generation PHS standard.

  FIG. 2 is a diagram illustrating a frame structure of the next generation PHS.

  One frame is composed of eight slots. The first four slots are uplink slots, and the last four slots are downlink slots. Further, each slot is composed of a plurality of subchannels in terms of frequency. As shown in the figure, a physical resource having a time width of one slot and a time width of one subchannel is called a PRU (Physical Resource Unit).

  Each PRU is numbered for each uplink and downlink. The first slot of the subchannel of the lowest frequency is PRU1, and the PRU number is incremented for each slot in the time direction, and the next of the fourth slot is connected to the first slot of the next lower frequency subchannel. So that it is numbered.

  The base station 11 assigns a pair of PRUs having the same number to the terminal 101 in the uplink and the downlink. For example, uplink PRU11 and downlink PRU11 are assigned in pairs, and uplink PRU14 and downlink PRU14 are assigned in pairs.

  FIG. 3 is a diagram illustrating a configuration example of the base station 11 of the next generation PHS to which the MIMO transmission scheme according to the present embodiment is applied. In the example of the figure, the case where the MIMO multiplexing number is 2 and two streams of stream 1 and stream 2 are transmitted is shown as an example.

  In the MIMO transmission system according to the present embodiment, the amount of feedback for determining transmission weights can be minimized by adding the functions and mechanisms according to the present invention to a simple extension of the next-generation PHS standard to multiple streams. The transmission weight control for each stream can be realized.

  The base station 11 includes a base station transmission unit 21, a base station reception unit 41, antennas 1 to M, and transmission / reception switching units 51-1 to 51-M. Hereinafter, first, operations related to the base station transmission unit 21, the antennas 1 to M, and the transmission / reception switching units 51-1 to 51-M will be described, and the operation of the base station reception unit 41 will be described about the operation of the terminal. This will be explained later.

  In FIG. 3, the DL-ECCH1 generation unit 22a generates DL-ECCH1 that is a DL-ECCH (Downlink-EXCH Control Channel) for the stream 1. Similarly, the DL-ECCH2 generation unit 22b generates DL-ECCH2, which is a DL-ECCH for the stream 2. DL-ECCH is a functional channel for control including PRU allocation information.

  The DL-EDCH1 generation unit 23a generates DL-EDCH1 that is a DL-EDCH (Downlink-EXCH Data Channel) for the stream 1. Similarly, the DL-EDCH2 generation unit 23b generates DL-EDCH2, which is a DL-EDCH for the stream 2. DL-EDCH is a functional channel that transmits data addressed to a terminal.

  The DL-ANCH modulation unit 25 generates a DL-ANCH (Downlink Anchor Channel) that is a physical frame including DL-ECCH1 and DL-ECCH2, and performs data modulation on the DL-ANCH. The physical frame format of DL-ANCH including DL-ECCH1 and DL-ECCH2 is shown in Fig. 4 (If the MIMO transmission method is not used, the format excluding DL-ECCH2 from the format of Fig. 4 is used) . Each field of DL-ECCH has the following meaning as defined in the next-generation PHS standard.

MAP: PRU location information used as EXCH (Extra Channel) allocated to the terminal (details of EXCH will be described later)
V: Number of PRUs used for DL-EDCH transmission among the PRUs specified in MAP (details of DL-EDCH will be described later)
SD: Transmission timing control information
PC: Transmission power control information
ACK: ACK / NACK for UL-EDCH
MI: Modulation and coding method applied to EXCH specified by MAP
MR: Specification of modulation and encoding method in UL-EDCH
HC: HARQ (Hybrid Automatic Repeat reQuest) cancellation instruction

  In FIG. 4, in MAP, PRU allocation information for the corresponding stream is transmitted in a bitmap of 1 and 0. 1 means that a PRU is assigned, and 0 means that no PRU is assigned. The illustrated MAP origin is the origin of the PRU in the range specified by the MAP field, and the MAP area means a valid PRU range indicated by the MAP field. These are determined at the time of connection in the next-generation PHS standard, and may be considered to be fixed once communication is started. In the present embodiment, it is assumed that the MAP origin and the MAP area are common to all streams.

  The MAP of stream 1 corresponds to first control information indicating physical resources used for data transmission of stream 1, and the MAP of stream 2 corresponds to second control information indicating physical resources used for data transmission of stream 2. To do. More generally, when there are K streams, each MAP of the first to Kth streams corresponds to first to Kth control information indicating physical resources used for data transmission of the first to Kth streams. To do. Therefore, the DL-ECCH1 generation unit 22a and the DL-ECCH2 generation unit 22b correspond to the first and second control information generation means of the present invention. More generally, when there are K streams, the base station transmission unit 21 includes first to Kth control information generation means.

  Fields such as SD, PC, ACK, and MR transmit control information for the uplink. If the MIMO transmission method is applied only to the downlink and the MIMO transmission method is not applied to the uplink, it is sufficient to have one of these fields for DL-ANCH. Therefore, in this case, the hatched field of DL-ECCH2 is unnecessary, and there is no problem even if the field itself does not exist.

  The DL-ECCH1 generation unit 22a and the DL-ECCH2 generation unit 22b described above generate a DL-ECCH1 MAP and a DL-ECCH2 MAP having fields as shown in FIG. Shall. The used PRU determination unit 47 has a function of determining a PRU to be allocated to a terminal for each stream, and the detailed operation will be described later. Note that the DL-ECCH1 generation unit 22a and the DL-ECCH2 generation unit 22b may allocate a PRU at a predetermined position to a terminal in the initial stage.

  The output signal of the DL-ANCH modulation unit 25 (an ANCH signal including the MAP (first and second control information) of the streams 1 and 2) is transmitted to the specific DL-ANCH determined at the time of connection in the stream 1 mapping unit 31a. Is mapped to the PRU for transmission and transmitted in the PRU. Therefore, the stream 1 mapping unit 31a includes control information transmitting means for transmitting the first to Kth control information of the present invention.

  In the present embodiment, DL-ANCH is transmitted by one PRU of one stream as in the case where the MIMO transmission scheme is not applied. Therefore, the necessary MCS (Modulation and Coding Scheme) needs to be changed according to the number of bits of DL-ANCH. In the case of FIG. 4, since it is necessary to use MCS (encoded modulation system) that can transmit two DL-ECCHs, the DL-ANCH modulation unit 25 uses MCS No. 0 (4-bit notation: 0000). It is necessary to use No. 1 (4-bit notation: 0001) instead of. Numbers such as 0 and 1 are MCS numbers assigned to the coded modulation scheme, and the larger the MCS number, the higher the transmission rate.

  As a DL-ANCH format for a terminal having a MIMO function, there are always two formats depending on whether the number of streams is 1 or 2 (the format of FIG. 4 and the format of FIG. 4). It is also possible to use a different format (excluding DL-ECCH2 of stream 2). The following methods can be considered for proper use.

1. Switching with a control message (for example, notifying the terminal that the format of FIG. 4 is to be used from the next frame).
2. As in CSCH (CSCH is defined in the standard), the applicable MCS information is sent to the terminal as “SIGNAL” (the terminal uses the MCS information to determine the format used. Note that SIGNAL has a fixed MCS. Is used.)
3. Which format is blinded is detected on the terminal side (for example, a format that can be correctly demodulated using CRC or the like is determined to be a used format).

  In this example, the number of streams is two, but DL-ECCH3 and DL-ECCH4 are defined in the same way for three and four streams, and DL-ECCH3 and DL-ECCH4 are defined. It is possible to generate an included DL-ANCH and select an MCS (encoded modulation scheme) that matches the DL-ANCH size.

  The weight 1 application unit 32a applies (multiplies) the transmission weight for stream 1 calculated by the weight calculation unit 48 described later to the DL-ANCH mapped by the stream 1 mapping unit 31a to the designated PRU. . The signal to which the transmission weight is applied is input to OFDM transmitters 34-1 to 34-M provided for each transmission antenna and converted into an OFDM signal, and each OFDM signal is transmitted to and received from transmission / reception switching units 51-1 to 51-1. It transmits toward the terminal from the plurality of antennas 1 to M switched to downlink transmission by 51-M. Note that adders 35-1 to 35 -M are arranged before the OFDM transmitters 34-1 to 34 -M. Each of the adders 35-1 to 35-M adds the output signals from the weight 1 applying unit 32a and the weight 2 applying unit 32b and inputs the added signals to the corresponding OFDM transmitting units 34-1 to 34-M. Since one stream including DL-ANCH is transmitted and the other streams are not transmitted, the signal to which the transmission weight is applied is not added to the other signal, and the OFDM transmitters 34-1 to 34-M Is input.

  With the PRU specified in DL-ECCH1 and DL-ECCH2 according to the next-generation PHS standard for each stream in the next frame (or next next frame) that transmitted DL-ANCH including DL-ECCH1 and DL-ECCH2, DL-EDCH, which is data addressed to the terminal, is transmitted. The DL-EDCH is transmitted by the physical frame format EXCH (Extra Channel) in the PRU specified by the MAP and V shown in FIG.

  That is, the DL-EDCH1 generation unit 23a in FIG. 3 generates the DL-EDCH of the stream 1 according to the PRU specified by the previously transmitted DL-ECCH1. The generated DL-EDCH is modulated in accordance with the physical format of the EXCH in the DL-EXCH modulation unit 24a, and is mapped to the PRU at the designated position and transmitted in the stream 1 mapping unit 31a. Similarly for stream 2, the DL-EDCH generated by the DL-EDCH2 generation unit 23b is modulated by the DL-EXCH modulation unit 24b, mapped to the PRU at the designated position, and transmitted as the EXCH of stream 2. The mapping of DL-EDCH1 and DL-EDCH2 in the stream 1 mapping unit 31a and the stream 2 mapping unit 31b is performed according to an instruction from the use PRU determination unit 47 described later. The stream 1 mapping unit 31a or the stream 2 mapping unit 31b uses the physical resource specified by the DL-ECCH1 MAP (first control information) and the physical resource specified by the DL-ECCH2 MAP (second control information). And a data transmission means for transmitting data stream 1 and stream 2. More generally, the base station includes data transmission means for transmitting the first to Kth streams including data (DL-EDCH) using physical resources specified by the first to Kth control information.

  FIG. 5 is a diagram illustrating a configuration example of DL-EDCH in the case of DL-ECCH1 and DL-ECCH2 illustrated in FIG. In FIG. 4, a case where the number of 1s of MAPs and the value of V are the same will be described as an example. The CRCH and DTX shown in the lower part of the drawing will be described later.

  As shown in FIG. 5, in each slot, when the number of assigned PRUs is an even number, the size of the EDCH is all equivalent to two PRUs, and when the number of assigned PRUs is an odd number, The size of the last EDCH is one PRU.

  For example, in slot 1 of stream 1, the number of PRUs is 4, so two EDCHs that are the size of two PRUs are transmitted, and in slot 2, the number of PRUs is 3, so the size is two PRUs. EDCH and EDCH that is the size of one PRU are transmitted. Also, since the number of PRUs is 6 in slot 1 of stream 1, 3 EDCHs, which is the size of 2 PRUs, are transmitted, and the number of PRUs is 2 in slot 4 of stream 1, so the size is 2 PRUs. One EDCH is transmitted.

  As described above, the number and size of the DL-EDCH generated by the DL-EDCH1 generation unit 23a and the DL-EDCH2 generation unit 23b vary depending on the number of assigned PRUs for each slot. The DL-EDCH1 generation unit 23a and the DL-EDCH2 generation unit 23b generate DL-EDCH using the PRU position information in each slot designated by the use PRU determination unit 47 described later.

  In the CRCH1 generation unit 26a and the CRCH2 generation unit 26b in FIG. 3, “CRCH (CQI Request Channel)”, which is a function channel newly defined for the next-generation PHS standard in the present invention, Generate for.

  In the example shown in FIG. 5, a case where CRCH exists only for stream 2 is shown. The purpose of CRCH is to feed back the CQI information of the PRU corresponding to the CRCH so that the response to the EDCH is ACK / NACK. Details of the uplink response to CRCH will be described later.

  The CRCH generated for each stream in the CRCH1 generation unit 26a and the CRCH2 generation unit 26b is modulated as DTX into the physical format of the PRU in the DTX modulation units 27a and 27b, and the stream 1 mapping unit 31a and the stream 2 mapping unit In 31b, it is mapped to the PRU at the designated position.

  Here, as shown in FIG. 5, DTX is defined as the physical format of the PRU corresponding to CRCH. DTX itself is already defined in the next-generation PHS standard. Here, DTX means an EXCH format in which all data symbols are null (DTX symbols), particularly as a PRU format. That is, only a known signal (pilot signal or training signal) is transmitted in a PRU (first physical resource) denoted as DTX. In other words, CRCH only means correspondence with PRU which is DTX, and does not include specific information. As will be described later, the terminal that receives the DTX transmitted by this PRU measures the channel quality of this PRU using this DTX (known signal), and transmits the CQI information indicating the measured quality in the ACK field (ACK information return). To the base station using the Therefore, it can be said that DTX is a measurement signal (known signal) for measuring the channel quality of the PRU (physical resource) in the terminal. As described above, DTX itself is already defined in the next-generation PHS standard, but in this embodiment, DTX associated with the newly defined CRCH is particularly called a quality measurement signal. However, the quality measurement signal of the present invention is not limited to such DTX, and may be any form of signal as long as the quality can be measured in the terminal.

  As described above, in the present embodiment, in the MAP related to a certain stream (k2th stream), when the specified PRU is not specified in the MAP related to another stream (k1st stream), the PRU ( The k2th stream including DTX (known signal) is transmitted using the first physical resource. That is, the k2 stream including DTX is transmitted when the PRU specified in the MAP related to the k1 stream is not specified in the MAP related to the k2 stream.

  A PRU (first physical resource) satisfying such a condition is detected by the used PRU determination unit 47. The used PRU determination unit 47 detects a first physical resource (PRU) that is specified by the MAP (first control information) of the stream 1 and is not specified by the MAP (second control information) of the stream 2 ( Base station detection means). The detected PRU is notified to the CRCH1 generator 26a and the CRCH2 generator 26b. The CRCH1 generation unit 26a and the CRCH2 generation unit 26b generate CRCH1 and CRCH2 for transmission using the notified PRU (an example of the configuration of the CRCH will be described later). CRCH1 and CRCH2 are modulated as DTX (quality measurement signal) by the DTX modulators 27a and 27b into the physical format of the PRU, and the stream 1 mapping unit 31a and the stream 2 mapping unit 31b specify the PRU ( The first physical resource is mapped and transmitted. Therefore, the stream 1 mapping unit 31a or the stream 2 mapping unit 31b receives the stream 1 or the stream 2 including DTX (measurement signal) for measuring the channel quality of the detected physical resource (first physical resource) at the terminal. And a signal transmission means for transmitting using the detected physical resource.

  More generally, when there are K streams, the use PRU determination unit 47 is designated by a MAP (k1 control information) related to the k1th stream and a MAP (k2th control information) related to the k2th stream. It has a detection means (base station detection means) for detecting a first physical resource (PRU) that is not specified. Here, k1 is any value from 1 to K, and k2 is a value different from k1 from 1 to K. And the signal which transmits the said k2 stream containing the signal for a quality measurement for measuring the channel quality of the said detected physical resource (1st physical resource) in the terminal by the said detected physical resource (1st physical resource) The base station includes a transmission means in a stream mapping unit corresponding to the k2th stream.

  Hereinafter, two configuration examples of the CRCH (first configuration example and second configuration example) will be described.

  First, a first configuration example of CRCH according to the present embodiment will be described with reference to the lower part (stream 2) of FIG.

  In the first configuration example of CRCH, the CRCH is configured so that the total number of EDCH and CRCH for each slot (or for each frame) matches between the streams. For this purpose, as shown in the lower part of FIG. 5, when the number of DTXs per slot is an even number, the logical order of PRUs per slot (that is, the order of younger PRUs in the same slot) Accordingly, one CRCH corresponds to every two DTXs, and when the number of DTXs is an odd number, the last CRCH corresponds to one DTX, and the other CRCHs correspond to two DTXs. In this way, the total number of EDCH and CRCH for each slot (or for each frame) can be matched between the streams.

  As an exception, if an even number of PRUs are assigned to EXCH in a slot for a stream A and an odd number of these PRUs are assigned to EXCH for another stream B, the last one DTX as one CRCH When counted, the total number of EDCH and CRCH increases by one in stream B. In such a case, the last DTX should not be set to CRCH. Alternatively, the last DTX may be included in another CRCH (in this case, the other CRCH may include three or more PRUs).

  Note that such an exceptional situation is that, as an EXCH allocation rule, if there is an even number of PRUs that are EXCH in a slot related to stream A, EXCH must always be assigned when these PRUs are also allocated in that slot for stream B. This can be easily avoided by assigning an even number.

  FIG. 6 is a diagram illustrating a second configuration example of the CRCH according to the present embodiment.

  In the second configuration example, one CRCH is assigned to each DTX. In this case, the total number of CRCH and EDCH may differ depending on the stream. For this reason, it may not be ensured to secure a field for feeding back necessary CQI information (CQI information is returned in an unused field among ACK fields for returning ACK information). In such a case, CQI information should be included in the field as much as possible. Accordingly, the number of CRCHs may be limited according to the number of CQI information (that is, since the ACK field size (bit size) is predetermined), the number of DL-EDCHs to be transmitted, the ACK field size, The number of CRCHs may be limited to the CQI information returnable size determined from

  The CRCH1 generation unit 26a and the CRCH2 generation unit 26b described above generate a CRCH according to the assignment rule shown in the first or second configuration example. It is assumed that what kind of allocation rule is used is shared with the terminal in advance.

  The EDCH and CRCH mapped to the PRU for each stream are transmitted to the stream 1 transmission weight and the stream 2 calculated by the weight calculation unit 48 described later in the weight 1 application unit 32a and the weight 2 application unit 32b of FIG. By applying the transmission weight, a weight multiplication signal for each of the antennas 1 to M is generated. The weight multiplication signals for the respective antennas 1 to M generated by the weight 1 application unit 32a and the weight 2 application unit 32b are respectively input to the addition units 35-1 to 35-M and added, and the addition unit 35-1 ... -35-M are converted into OFDM signals by OFDM transmitters 34-1 to 34-M provided for each transmission antenna. Each OFDM signal is transmitted toward the terminal from the plurality of antennas 1 to M that are switched to downlink transmission by the transmission / reception switching units 51-1 to 51-M.

  FIG. 7 is a diagram illustrating a configuration example of a next-generation PHS terminal to which the MIMO transmission system receiver according to the present embodiment is applied. The terminal in FIG. 7 demodulates two streams MIMO-transmitted from the base station shown in FIG. 3, and transmits necessary feedback information (uplink control information). Since the number of reception antennas necessary for reception of downlink 2-stream transmission is two or more, the number of reception antennas of the terminal is set to two here.

  In the following, for simplicity of explanation, it is assumed that the MIMO transmission scheme is not applied to the uplink signal transmitted from the terminal of FIG. 7, and the uplink signal is one stream. However, the DL-ANCH / UL-ANCH format, the structure of CRCH and CQI information, and these transmission / reception methods in the present embodiment are also applicable when the MIMO transmission scheme is used in the uplink.

  First, a reception operation in a DL-ANCH terminal transmitted from a base station will be described.

  DL-ANCH is transmitted as one stream (in this example, stream 1) from the base station even when the MIMO transmission method is applied. You can think of it as the same. That is, as shown in FIG. 7, the signal received by the antenna 1 is input to the OFDM receiver 142a via the transmission / reception switching unit 151 (the transmission / reception switching unit 151 is set to downlink reception) and received by the antenna 2. The received signal is input to the OFDM receiver 142b. The received signals input to the OFDM receivers 142a and 142b are converted into frequency data by the OFDM receivers 142a and 142b and input to the communication path estimator 143. The communication path estimation unit 143 uses the frequency data of known signals related to each PRU included in the frame to which the DL-ANCH is transmitted and the data of known signals (training signals and pilot signals) held in advance. The communication path of stream 1 is estimated. With regard to DL-ANCH, since stream separation is not necessary, the MIMO demodulator 144 performs diversity combining using the frequency data of each PRU and the estimated value of the communication path. The diversity-combined DL-ANCH is taken out by the stream 1 demapping unit 145a and subjected to data demodulation processing by the DL-ANCH demodulating unit 146, and separated into DL-ECCH1 and DL-ECCH2 as shown in FIG. The The separated DL-ECCH1 and DL-ECCH2 are decoded by the DL-ECCH1 decoding unit 147a and the DL-ECCH2 decoding unit 147b, respectively. 144, and is notified to the stream 1 demapping unit 145a and the stream 2 demapping unit 145b. Among the values of each field, in particular, the MAP in DL-ECCH1 is the first control information indicating the physical resource used for data transmission of stream 1 as described above, and the MAP in DL-ECCH2 is the data of stream 2 This corresponds to second control information indicating a physical resource used for transmission. The terminal includes control information receiving means for receiving DL-ANCH including first and second control information. More generally, when there are K streams, the terminal includes control information receiving means for receiving first to Kth control information indicating physical resources used for data transmission of the first to Kth streams. The control information receiving means is included in the stream 1 demapping unit 145a that extracts the DN-ANCH including the first and second control information, for example.

  Next, the reception operation in the terminal of DL-EDCH and CRCH transmitted from the base station in the next frame (or next next frame) of the frame in which DL-ANCH is transmitted will be described.

  Similar to the DL-ANCH reception operation, the signals received by the antennas 1 and 2 are converted into frequency data by the OFDM receivers 142a and 142b, and the DL-EDCH and CRCH are transmitted by the communication path estimation unit 143. The communication paths of the respective streams 1 and 2 are estimated using the frequency data of known signals related to each PRU and the data of known signals (training signals and pilot signals) held in advance. The estimated value of the communication path and the frequency data of each PRU are sent to the MIMO demodulator 144.

  The MIMO demodulator 144 knows which PRU is EXCH (DL-EDCH) or DTX (CRCH) for each stream based on the previously notified DL-ECCH1 and DL-ECCH2. That is, the MIMO demodulator 144 detects a physical resource (PRU) that is specified by the MAP (first control information) of the stream 1 and not specified by the MAP (second control information) of the stream 2 (terminal). Detection means). It also includes detection means for detecting a physical resource (PRU) specified by both the MAP (first control information) of stream 1 and the MAP (second control information) of stream 2. The MIMO demodulator 144 notifies the position of these detected physical resources to the stream 1 demapping unit 145a and the stream 2 demapping unit 145b.

  More generally, the MIMO demodulator 144 includes detection means (terminal detection means) that detects physical resources that are designated by the k1th control information and not designated by the k2th control information when there are K streams. , And a function of notifying the position of the detected physical resource to the stream demapping unit corresponding to the k2th stream. Note that k1 is any value from 1 to K, and k2 is a value different from k1 from 1 to K. Further, the MIMO demodulator 144 includes detection means for detecting a physical resource specified by both the k1th control information and the k2th control information, and the detected physical resource position corresponds to the k1th and k2th streams, respectively. Has a function to notify the stream demapping unit.

  These detection means are provided here in the MIMO demodulator 144, but such a detection means is separately provided outside the MIMO demodulator 144, and the MIMO demodulator 144 and the stream 1 decoder are separately provided from the separately provided detector. You may make it notify to the mapping part 145a and the stream 2 demapping part 145b.

  Hereinafter, the processing of the MIMO demodulator 144 will be described in more detail. The processing of the MIMO demodulator 144 differs depending on the PRU.

  That is, in the case of a PRU in which one stream is EXCH and the other stream is DTX, the data symbol part of the PRU is transmitted by one stream, so no special processing for separating the streams is necessary. One stream, EXCH (DL-EDCH), is extracted by the stream 1 demapping unit 145a or the stream 2 demapping unit 145b and sent to the DL-EDCH demodulation unit 148a or 148b. The other stream, DTX, is extracted by the stream 2 demapping unit 145b or the stream 1 demapping unit 145a and sent to the CRCH demodulation unit 149b or 149a. The correspondence between CRCH and PRU (DTX) can be grasped by sharing the above-described allocation rule with the base station. The CRCH demodulator 149b or 149a measures the CRCR SINR (Signal to Interference and Noise Ratio) based on the DTX (known signal) constituting the CRCH, and the measured SINR is used as the CQI calculator 123. Send to. The CRCH demodulator 149b or 149a includes quality measurement means for measuring the quality of the DTX constituting the CRCH (that is, the quality of the first physical resource).

  For a PRU in which both streams are EXCH, the MIMO demodulator 144 needs to separate the two streams. A typical method of MIMO demodulation will be described later. Each EXCH (DL-EDCH) separated into stream 1 and stream 2 by MIMO demodulation section 144 is extracted by stream 1 demapping section 145a and stream 2 demapping section 145b, and DL-EDCH demodulation section 148a of each stream is extracted. And 148b. Therefore, the stream 1 demapping unit 145a and the stream 2 demapping unit 145b receive the data assigned to the PRUs specified by the MAP (first control information) of the stream 1 and the MAP (second control information) of the stream 2, respectively. Data receiving means for receiving is provided. Note that an allocation rule between DL-EDCH and PRU (EXCH) is preliminarily held in common with the base station.

  In the DL-EDCH demodulation units 148a and 148b, each EDCH is demodulated and decoded, and whether or not the EDCH is successfully received is confirmed by a CRC check bit, and the result (success or failure) is obtained as the UL- The data is sent to the ECCH1 generation unit 122a and the UL-ECCH2 generation unit 122b.

  Here, the operation of the CQI calculation unit 123 will be described.

  When the CQI calculation unit 123 receives the SINR value corresponding to each CRCH from the CRCH demodulation unit 149a or 149b, the CQI calculation unit 123 determines whether the SINR value corresponding to each CRCH is equal to or greater than a threshold. If it is less than the threshold value, 0 is generated and output to the UL-ECCH generation unit (122a or 122b) of the corresponding stream. “1” and “0” are CQI information for notifying the base station whether the quality of the PRU that transmitted the CRCH is good, and indicates whether the transmission weight applied to the CRCH is appropriate. It is also an indicator. “1” means that the quality of the PRU that transmitted the CRCH is good (the transmission weight applied to the CRCH is appropriate), and “0” indicates that the quality of the PRU that transmitted the CRCH is not good (transmission applied to the CRCH) This means that the weight is not appropriate. Note that, as described above, the CRCH corresponds to one or more PRUs, and thus the CCHI information of the CRCH is 1-bit CQI information for one or more physical resources. The quality (SINR) measurement means included in the CRCH demodulation sections 149a and 149b and the CQI calculation section 123 that generates CQI information based on the measurement quality form the CQI information generation means of the present invention.

  Hereinafter, SINR threshold setting methods (first to fourth setting methods) in CQI calculation section 123 will be described.

  The first setting method is to set the average SINR of EXCH in the same slot as CRCH as a threshold value. The stream for which the average calculation is performed may be only a stream including CRCH, all streams (that is, the first to Kth streams), or an arbitrary number of streams selected from all streams.

  The second setting method is to set a minimum SINR required for MCS (coded modulation scheme) derived from the average SINR of EXCH in the same slot as the CRCH as a threshold value. That is, the minimum SINR value required for the MCS calculated according to the standard from the received EXCH SINR is used as the threshold value. More specifically, a different one of a plurality of coded modulation schemes is associated with each SINR value range, and the minimum value of the range corresponding to the coded modulation scheme corresponding to the average SINR is set as a threshold value. The stream for which the average calculation is performed may be only a stream including CRCH, all streams (that is, the first to Kth streams), or an arbitrary number of streams selected from all streams.

  A third setting method is to set a value obtained by subtracting a certain value from the average SINR of another stream in the same slot as the CRCH as a threshold value. For example, a value obtained by subtracting a certain value from the average SINR of the same slot of stream 1 (that is, a value obtained by adding a certain offset) is determined as a threshold (basically, the quality of stream 1 is more stable than that of stream 2) is doing). In this case, stream 1 corresponds to the k1 stream of the present invention, and stream 2 corresponds to the k2 stream of the present invention.

  The fourth setting method is to set the minimum SINR value necessary for applying MCS (encoded modulation system) of MCS number obtained by subtracting a certain value from MCS number of another stream in the same slot as CRCH. (MCS shall be determined in slot units). For example, the minimum SINR value required to apply the MCS of the MCS number obtained by subtracting a certain value from the MCS number of the MCS applied to the same slot of stream 1 (that is, the MCS number with a certain offset added). Is set as a threshold value. More specifically, a different one of a plurality of coded modulation schemes is associated with each of the SINR value ranges, and the first coded modulation scheme used for data transmission of stream 1 is used in the same slot as the CRCH. On the other hand, the minimum value in the range corresponding to the second coded modulation scheme having one or a plurality of stages and a low or high transmission rate is set as the threshold value.

  However, the meaning of “average” for “average SINR” in the above is such that the error rate of EDCH when SINR varies for each EXCH is equal to the error rate characteristic of EDCH when SINR is the same for all EXCHs. Furthermore, this means that a plurality of SINR values are converted into a single value.

  Next, the operation when the terminal transmits UL-ECCH for notifying the base station of ACK information based on the DL-EDCH demodulation result (whether or not reception was successful), CCHI information of CRCH, etc. will be described. To do.

  In FIG. 7, UL-ECCH1 generation unit 122a and UL-ECCH2 generation unit 122b generate UL-ECCH1 of stream 1 and UL-ECCH2 of stream 2. At this time, the UL-ECCH1 generation unit 122a and the UL-ECCH2 generation unit 122b generate an ACK (for example, bit “1”) indicating the reception success for the EDCH notified of the reception success, and the failure is notified. For EDCH, an ACK (for example, bit “0”) indicating a reception failure is generated, and the generated ACK / NACK is included in UL-ECCH. Each of the UL-ECCH1 generation unit 122a and the UL-ECCH2 generation unit 122b includes a delivery confirmation generation unit that generates delivery confirmation information (ACK / NACK) indicating whether or not reception of EDCH (received data) is successful. The UL-ECCH format is basically the same as when the MIMO transmission method is not used.

  FIG. 8 is a diagram illustrating a UL-ANCH (feedback information) configuration including UL-ECCH1 and UL-ECCH2 of stream 1 and stream 2 when the MIMO transmission scheme is applied. The functions of each UL-ECCH field are summarized below.

RCH: Number of PRUs to be assigned
V: Number of PRUs used for EDCH transmission per slot in the same frame as UL-ANCH
ACK: ACK / NACK for DL-EDCH and CQI information for CRCH
MI: Modulation and coding method applied to UL-EXCH specified by MAP
MR: Specification of desired modulation and coding method in DL-EDCH
HC: HARQ cancellation instructions

  The UL-ANCH configuration is basically the same as the next-generation PHS standard, but in this embodiment, a new function is added only to the ACK field. That is, as shown in FIG. 8, when the MIMO transmission method is applied, in the UL-ECCH ACK field, in addition to ACK / NACK (acknowledgment information), a CQI representing a response to each CRCH by 1 bit. Information is sent and sent. The ACK fields of UL-ECCH1 and UL-ECCH2 shown in FIG. 8 are responses to EDCH and CRCH shown in FIG.

  As shown in FIG. 8, in the first configuration example of the ACK field according to the present embodiment, the ACK / NACK and CQI information are arranged in the order of ACK / NACK first, followed by CQI information. Deploy. That is, the ACK field is composed of concatenated bits in which a bit string of ACK / NACK (acknowledgment information) and a bit string of CQI information are concatenated in this order. Therefore, more generally, UL-ANCH (feedback information) includes first to Kth concatenated bit strings obtained by concatenating a bit string of acknowledgment information and a bit string of CQI information for each of the first to Kth streams. If this first configuration example is adopted, the position of the ACK / NACK in the ACK field does not change even if there is a CRCH.

  FIG. 9 is a diagram illustrating a second configuration example of the ACK field according to the present embodiment. In the example of FIG. 9, the ACK / NACK bit and the CQI information bit are set as the EDCH and CRCH are arranged in the logical order of the PRU for each slot (that is, in the order in which the EDCH and CRCH are sent). Place them in the ACK field. That is, according to the order in which EDCH and CRCH are transmitted, ACK / NACK bits for EDCH and CRCQ CQI information bits are arranged in the ACK field. More generally, UL-ANCH (feedback information) includes first to Kth bit strings including a bit of acknowledgment information and a bit of CQI information for each of the first to Kth streams. The plurality of bits included in each of the K bit strings are arranged according to the order in which the data (EDCH) and the signal (CRCH) that are the generation sources of the delivery confirmation information and the CQI information are transmitted.

  7 generates UL-ANCH (feedback information) including the two UL-ECCH1 and UL-ECCH2 shown in FIG. 8, performs data modulation on the UL-ANCH, and will be described later. Transmission is performed via the signal multiplexing unit 127 and the transmission unit 128. Therefore, UL-ANCH modulation section 124 includes feedback transmission means for transmitting feedback information. As in the case of DL-ANCH, since a format in which two ECCHs are transmitted in one stream is assumed, the MCS (encoded modulation scheme) used in the UL-ANCH modulator 124 is also UL-ANCH. It is necessary to change according to the number of bits. In the case of FIG. 8, it is necessary to use No. 1 (4-bit notation: 0001) as MCS instead of No. 0 (4-bit notation: 0000). However, when the MIMO transmission scheme is not applied to the uplink, the fields (V, MI, HC) of the stream 2 in FIG. 8 are unnecessary. If the MIMO transmission method is not applied and the format compatibility is slightly ignored and these fields are eliminated, when the uplink is an OFDM signal, the reserved field (the remaining unused field) is used. It is also possible to use MCS number 0. Even when the number of streams is 3 or more, UL-ECCH may be added by the same method and MCS may be selected as necessary. As a method for notifying the MCS change, the same method as described in the previous DL-ANCH can be applied.

  In the UL-EDCH generation unit 125 of FIG. 7, UL-EDCH is generated, and the generated UL-EDCH is subjected to data modulation by the UL-EDCH modulation unit 126, and signal multiplexing is performed together with the output of the UL-ANCH modulation unit 124. The unit 127 maps to a predetermined PRU. The output signal of the signal multiplexing unit 127 is transmitted from the antenna 1 to which OFDM modulation or single carrier modulation is applied in the transmission unit 128 and switched to uplink transmission by the transmission / reception switching unit 151.

  Next, the operation of the base station receiving unit 41 in FIG. 3 when receiving an uplink signal will be described.

  In the OFDM receivers 42-1 to 42-M provided for each of the antennas 1 to M, the received signal is subjected to Fourier transform processing by the same processing as that of the conventional OFDM receiver, and the received data on the frequency is converted to PRU. Separate every time.

  Next, using the frequency data of the known signals (training signal and pilot signal) related to each PRU included in the uplink signal and the known signal data held in advance, the communication path estimation unit 43 uses the terminal Estimates the communication path (complex gain of the communication path) between the antenna used for transmission (here, the antenna 1 of the terminal) and each of the antennas 1 to M of the base station. The channel estimation value estimated here corresponds to a first vector representing the state of the channel between the base station and the terminal.

  The combining unit 44 combines the reception data output from the OFDM receiving units 42-1 to 42-M of the antennas 1 to M for each PRU. In general, combining is performed so that SINR (signal-to-noise interference power ratio) of the combined PRU using the channel estimation value is maximized.

  Data demodulation is performed in the UL-EXCH demodulation unit 45 when the combined signal is EXCH, and in the UL-ANCH demodulation unit 46 in the case of ANCH, in accordance with the next-generation PHS standard. However, the UL-ANCH demodulator 46 acquires UL-ECCH for each stream as shown in FIG. 8, and further acquires CQI information added to the ACK field.

  The use PRU determination unit 47 determines the PRU to be used for transmission of each stream using the value of the ACK field of the UL-ECCH for each stream (ACK information and CQI information). For example, when the CQI information of a PRU of a stream is 1, this PRU is set as a candidate PRU for transmitting EDCH. If the ACK information indicates an error (in the case of NACK), the PRU is excluded from the candidates for transmitting the EDCH, and the PRU with the incorrect ACK information is not used, or the CRCH is transmitted using the PRU. To. The used PRU determining unit 47 determines the PRU to be used for data transmission of each stream and the method of using the PRU, as described above, according to the CRCH1 generating unit 26a, the CRCH2 generating unit 26b, the DL-EDCH1 generating unit 23a, and the DL-EDCH2 The generation unit 23b, the DL-ECCH1 generation unit 22a, the DL-ECCH2 generation unit 22b, the stream 1 mapping unit 31a, and the stream 2 mapping unit 31b are notified. The usage PRU usage determination unit 47 can determine the usage PRU and the usage method for each stream and each frame using any method other than the above. In addition, another operation example of the used PRU determination unit 47 will be described later. In this embodiment, the use PRU determination unit 47 is provided in the base station reception unit 41, but the use PRU determination unit 47 is not necessarily provided in the base station reception unit 41. The base station receiver 41 and the base station transmitter 21 may be provided outside the station receiver 41 so as to communicate with each other.

  Also, the weight calculation unit 48 calculates the transmission weight for each stream using the channel estimation value calculated by the channel estimation unit 43 and the ACK field value (ACK information and CQI information) of the UL-ECCH, The calculated transmission weight is sent to the weight 1 application unit 32a and the weight 2 application unit 32b corresponding to each stream. The transmission weight for each stream is calculated for each PRU.

  Next, operations of the weight calculation unit 48 in FIG. 3 and the MIMO demodulation unit 144 in FIG. 7 will be described in detail.

  FIG. 10 is a diagram illustrating a relationship between a communication path between a base station and a terminal antenna and a transmission weight. In the example in the figure, the number of antennas of the base station is 4, and the number of antennas of the terminal is 2. The complex gain vector of the communication channel is defined as follows. The vector h1 corresponds to, for example, the first vector of the present invention.

Formula (1) h ₁ = [h _1,1 h _2,1 h _3,1 h _4,1 ] ^T
h ₂ = [h _2,2 h _2,2 h _3,2 h _4,2 ] ^T
Here, hm _{, n} is the complex gain of the communication path between the m-th antenna of the base station and the n-th antenna of the terminal. Further, a transmission weight vector applied to each stream in the base station is defined as follows.

Equation (2) w ₁ = [w _1,1 w _2,1 w _3,1 w _4,1 ] ^T
w ₂ = [w _2,2 w _2,2 w _3,2 w _4,2 ] ^T
In this case, two data symbols at the same position of the PRU to which the MIMO transmission scheme is applied are x = [x ₁ x ₂ ] ^T, and a received signal for the data symbol at the terminal is y = [y ₁ y ₂ ]. ^{If T} , it can be expressed as follows.

ただし、nは雑音成分のべクトルである。

Here, n is a vector of noise components.

  When applying the MMSE (Minimum-Mean Square Error) reception method in the MIMO demodulator 144 of FIG. 7, the following linear operation is applied to Equation (3). This performs stream separation.

Equation (4) z = (H ^H H + σ ² I) ^-1 H ^H y
Where I is a 4 × 4 unit matrix and σ ² is the variance of noise. Here, the MMSE reception method is taken as an example, but other methods may be used in the MIMO demodulator 144.

Next, for example, two transmission weight calculation methods represented by Expression (2) (first transmission weight calculation method and second transmission weight transmission method) will be described. The transmission weight is calculated by the weight calculation unit 48 in FIG. A case where the uplink is transmitted by one antenna as shown in FIG. 7 will be described as an example. In such a situation, the base station can estimate h ₁ in Equation (3) from the uplink signal transmitted from the terminal, but cannot estimate h ₂ .

  In the first transmission weight calculation method, as shown in Equation (5), the transmission weight of stream 1 is selected so that the SINR of stream 1 is maximized at antenna 1 of the terminal, and the transmission weight of stream 2 is selected. Selects a stream in which the stream 2 and the stream 1 are orthogonal (correlation is zero) in the antenna 1 of the terminal. However, a vector whose correlation is not zero and whose correlation with the vector of the stream 1 is equal to or smaller than the correlation threshold may be selected. That is, a set of vectors whose correlation is less than or equal to a threshold value is obtained, and a vector is selected from the set.

Equation (5) w ₁ = h ₁ / (h ₁ ^H h ₁ )
w ₂ : A vector whose magnitude is 1 at w ₂ ^H h ₁ = 0.

Where w ₁ and w ₂ are normalized. As specific w ₂ , any of the four column vectors included in the matrix W shown in the following equation (6) may be selected. Alternatively, a standardized vector represented by an arbitrary linear sum of these four column vectors may be used. Here, I is a unit matrix, and H represents transposition.

Equation (6) W = I-h ₁ h ₁ ^H / (h ₁ ^H h ₁ )

When transmission weights satisfying equation (5) are applied, as is apparent from equation (3), the interference from stream 2 to stream 1 is ideally eliminated at antenna 1 of the terminal. (x ₁ demodulation) makes it possible to perform data demodulation without applying the MMSE reception method described above. However, since the stream 2 of the antenna 2 of the terminal also includes the signal component from the stream 1, the MMSE reception method or the method of canceling by decision-feedback (determination feedback) after determining x ₁ Data demodulation is performed.

  In the second transmission weight calculation method, unlike the first transmission weight calculation method, a transmission weight (vector) is selected from a code book that is a set of vectors that are candidates for transmission weights defined in advance. Define the codebook as follows:

Equation (7) C = {c _k | k = 1,2,…, K}
Here, c _k is the k-th vector, and K is the total number of vectors. In the second transmission weight calculation method, a transmission weight is selected as follows.

Equation (8) w ₁ = {c _k | max (c _k ^H h ₁ )}
any c _k satisfying w ₂ : {c _k | c _k ^H h ₁ <correlation threshold}

In the first transmission weight calculation method and the second transmission weight calculation method described above, several candidates for the transmission weight w ₂ for the stream 2 are prepared instead of one. _{This is because 2} is unknown (h ₂ cannot be estimated), so if the selected w ₂ is inappropriate, it is necessary to switch to another w ₂ .

  The transmission weight switching method will be described below. This method is executed by the weight calculation unit 48 of FIG. 3 based on feedback information from the terminal input from the UN-ANCH demodulation unit 46 of the base station.

When CQI information, which is a response from a terminal when a CRCH newly defined in the present embodiment is transmitted from the base station, is 0 (that is, the quality of the PRU (first physical resource) that transmitted the CRCH is below the threshold ), The transmission weight applied to the CRCH stream is considered inappropriate. In this case, equation (5) or are prepared a plurality of candidates as w ₂ of the formula (8), when the CQI information is 0, and sequentially changing the transmission weight to be applied CRCH Send.

  Here, the use PRU determination unit 47 may determine that the PRU of the CQI information is not used for data transmission of the stream when 0 CQI information continues for a certain number of times or more. In addition, when the CQI information is 1 (that is, when the quality of the PRU (first physical resource) that transmitted the CRCH is larger than the threshold value), the used PRU determination unit 47 sets the PRU of the CQI information in the stream. You may determine as a candidate of a physical resource (PRU) for transmitting DL-EDCH data. For example, by intentionally preparing a PRU for transmitting a CRCH and further changing the PRU for transmitting a CRCH for each frame, it is possible to appropriately hold the transmission weight for the entire PRU.

  So far, the case where the MIMO transmission method is applied to the downlink and the MIMO transmission method is not applied to the uplink has been described, but the present invention can also be applied to the case where the MIMO transmission method is applied to both the downlink and the uplink. It is. Even in such a case, the DL-ANCH and UL-ANCH defined in the present embodiment are in a format that also considers the case where the MIMO transmission scheme is applied to the uplink, and therefore include the CRCH configuration and CQI information. The configuration of the ACK field, the transmission weight switching method, and the like can be basically applied as they are (without being changed).

  As described above, according to this embodiment, in a wireless communication system to which MIMO transmission technology is applied, a known signal for quality measurement is transmitted using physical resources that are not used in other streams, and is a next-generation PHS standard. The CQI information for the physical resource is fed back using the ACK field defined in, so that the transmission weight for each stream can be controlled with a small amount of feedback without performing frequent CQI reports for each stream. realizable.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

11: base station 1 to M: antenna 21: base station transmitter 22a, 22b: DL-ECCH generator 23a, 23b: DL-EDCH generator 24a, 24b: DL-EXCH modulator 25: DL-ANCH modulator 26a 26b: CRCH generation unit 27a, 27b: DTX modulation unit 31a, 31b: stream mapping unit 32a, 32b: weight application units 34-1 to 34-M: OFDM transmission units 35-1 to 35-M: addition unit 51- 1 to 51-M: transmission / reception switching unit 41: base station receiving unit 42-1 to 42-M: OFDM receiving unit 43: channel estimation unit 44: combining unit 45: UL-EXCH demodulating unit 46: UL-ANCH demodulating unit 47: Used PRU determination unit 48: Weight calculation unit 101: Terminal 1, 2: Antenna 121: Terminal transmission unit 122a, 122b: UL-ECCH generation unit 123: CQI calculation unit 124: UL-ANCH modulation unit 125: UL-EDCH Generation unit 126: UL-EDCH modulation unit 127: Signal multiplexing unit 12 : Transmitter 141: Terminal receiver 142a, 142b: OFDM receiver 143: Channel estimation unit 144: MIMO demodulator 145a, 145b: Stream demapping unit 146: DL-ANCH demodulator 147a, 147b: DL-ECCH decoder 148a, 148b: DL-EDCH demodulator 149a, 149b: CRCH demodulator

Claims (15)

A base station for transmitting K (K is an integer of 2 or more) streams to a terminal using a plurality of antennas, and MIMO (Multiple Input Multiple Output) transmission.
Control information generating means for generating first to Kth control information designating physical resources used for transmission of the first to Kth streams each including data;
Control information transmitting means for transmitting the first to Kth control information to the terminal;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Detection means for detecting physical resources;
Signal transmitting means for transmitting, using the first physical resource, the k2 stream including a quality measurement signal for measuring the channel quality of the first physical resource at the terminal;
A base station characterized by comprising: Communication path estimation means for estimating a first vector representing a state of a communication path with the terminal based on an uplink signal transmitted from the terminal;
Calculating a first transmission weight for transmitting the first stream from the first vector;
Weight calculating means for selecting second to Kth transmission weights for transmitting the second to Kth streams from a set of vectors whose correlation with the first vector is equal to or less than a correlation threshold;
The base station according to claim 1, further comprising: The weight calculation means, when CQI (Channel Quality Indicator) information, which is a response from the terminal to the quality measurement signal, indicates that the channel quality of the first physical resource is below a threshold value, The base station according to claim 2, wherein a k2 transmission weight for transmitting the k2 stream including a signal is changed to another vector in the set of vectors. When the CQI information, which is a response from the terminal to the quality measurement signal, indicates that the channel quality of the first physical resource is greater than a threshold value, the first physical resource is used for data transmission of the k2 stream. A physical resource determining means for determining physical resource candidates;
The base station according to claim 2 or 3, wherein the control information generating unit generates k2th control information for designating a candidate determined by the physical resource determining unit. When the first vector is represented as h1, the set of vectors includes a plurality of column vectors included in a matrix W = I−h1 × h1 ^H / (h1 ^H × h1), and a linear sum of the plurality of column vectors. 5. The base station according to claim 2, wherein I is a unit matrix, and H is a transpose. A terminal that receives first to Kth (K is an integer of 2 or more) streams transmitted from a base station via MIMO (Multiple Input Multiple Output) using a plurality of antennas,
Control information receiving means for receiving, from the base station, first to K-th control information specifying physical resources used for transmitting the first to K-th streams each including data;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Detection means for detecting physical resources;
Data receiving means for receiving the data of the first to Kth streams via the physical resource specified by the first to Kth control information;
Data demodulating means for demodulating each of the data;
A delivery confirmation generating means for generating delivery confirmation information for each of the data based on whether each of the data is correctly demodulated;
CQI information generating means for measuring the quality measurement signal of the k2th stream transmitted from the base station via the first physical resource and generating CQI information representing the channel quality of the first physical resource;
Feedback transmission means for transmitting feedback information including the delivery confirmation information of each data of the first to Kth streams and the CQI information of the first physical resource to the base station;
A terminal comprising:   The terminal according to claim 6, wherein the CQI information generation unit generates the CQI information indicating whether or not a quality of the quality measurement signal is greater than a threshold value. The CQI information generating unit generates 1-bit CQI information for one or a plurality of first physical resources to which the k2 stream including the quality measurement signal is transmitted. The listed terminal. A physical resource used for data transmission of the first to Kth streams belongs to one of a plurality of slots,
The quality of the quality measurement signal is SINR (Signal to Interference and Noise Ratio),
The threshold is an average SINR of a plurality of physical resources that are in the same slot as the first physical resource and used for data transmission of at least one stream selected from the first to Kth streams. The terminal according to claim 7 or 8. A physical resource used for data transmission of the first to Kth streams belongs to one of a plurality of slots,
The quality of the quality measurement signal is SINR,
A different one of a plurality of coded modulation schemes of the data transmission is associated with each of a plurality of ranges of SINR values,
The threshold is in the same slot as the first physical resource and is encoded according to an average SINR of a plurality of physical resources used for data transmission of at least one stream selected from the first to Kth streams The terminal according to claim 7 or 8, wherein the terminal is a minimum value of the range corresponding to a modulation scheme. A physical resource used for data transmission of the first to Kth streams belongs to one of a plurality of slots,
The quality of the quality measurement signal is SINR,
The threshold value is a value obtained by adding a certain offset to an average SINR of a plurality of physical resources that are in the same slot as the first physical resource and are used for data transmission of the k1 stream. Item 9. The terminal according to Item 7 or 8. A physical resource used for data transmission of the first to Kth streams belongs to one of a plurality of slots,
The quality of the quality measurement signal is SINR,
A different one of a plurality of coded modulation schemes of the data transmission is associated with each of a plurality of ranges of SINR values,
The threshold is in the same slot as the first physical resource, and is one or more stages in the first coded modulation scheme used for data transmission of the k1 stream, and a second code having a low or high transmission rate. The terminal according to claim 7 or 8, wherein the terminal is a minimum value in the range corresponding to a modulation modulation scheme. The delivery confirmation information and the CQI information are each represented by 1 bit,
The feedback information includes first to Kth concatenated bit strings obtained by concatenating the bit string of the delivery confirmation information corresponding to each of the first to Kth streams and the bit string of the CQI information.
The terminal according to any one of claims 6 to 12, characterized in that: The delivery confirmation information and the CQI information are each represented by 1 bit,
The feedback information includes first to Kth bit strings including bits of the acknowledgment information and bits of the CQI information corresponding to the first to Kth streams, respectively.
The plurality of bits included in each of the first to Kth bit strings are arranged according to the order in which the data and signals that are the generation sources of the delivery confirmation information and the CQI information are sent. The terminal according to any one of claims 6 to 12. A wireless communication system that performs MIMO (Multiple Input Multiple Output) transmission of first to Kth streams (K is an integer of 2 or more) from a base station to a terminal using a plurality of antennas,
The base station
Control information generating means for generating first to Kth control information designating physical resources used for transmission of the first to Kth streams each including data;
Control information transmitting means for transmitting the first to Kth control information to the terminal;
The first physical resource is designated by the k1th control information (k1 is any value from 1 to K) and is not designated by the k2th control information (k2 is a value different from k1 from 1 to K). Base station detection means for detecting physical resources;
Signal transmitting means for transmitting, using the first physical resource, the k2 stream including a quality measurement signal for measuring the channel quality of the first physical resource at the terminal;
Data transmitting means for transmitting the first to Kth streams including the data using physical resources specified by the first to Kth control information,
The terminal
Control information receiving means for receiving the first to Kth control information from the base station;
Terminal detection means for detecting the first physical resource based on the first to Kth control information;
Data receiving means for receiving the data of the first to Kth streams via the physical resource specified by the first to Kth control information;
Demodulation means for demodulating each of the data;
A delivery confirmation generating means for generating delivery confirmation information for each of the data based on whether each of the data is correctly demodulated;
CQI information generating means for measuring the quality measurement signal of the k2 stream transmitted from the base station via the first physical resource and generating CQI information representing the channel quality of the first physical resource;
Feedback transmission means for transmitting feedback information including the delivery confirmation information of each data of the first to Kth streams and the CQI information of the first physical resource to the base station;
A wireless communication system comprising:

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