Source: https://patents.google.com/patent/KR100952258B1/en
Timestamp: 2020-01-25 17:50:28
Document Index: 383265752

Matched Legal Cases: ['art 25', 'art 56', 'art 57', 'art 58', 'art 56', 'art 59', 'art 60']

KR100952258B1 - Relay station and method of measuring reception quality in relay station, and radio base station and method of selecting a route in radio base station - Google Patents
Relay station and method of measuring reception quality in relay station, and radio base station and method of selecting a route in radio base station Download PDF
KR100952258B1
KR100952258B1 KR20070076412A KR20070076412A KR100952258B1 KR 100952258 B1 KR100952258 B1 KR 100952258B1 KR 20070076412 A KR20070076412 A KR 20070076412A KR 20070076412 A KR20070076412 A KR 20070076412A KR 100952258 B1 KR100952258 B1 KR 100952258B1
KR20070076412A
KR20080016454A (en
마사또 오꾸다
2006-08-17 Priority to JPJP-P-2006-00222448 priority
2007-07-30 Application filed by 후지쯔 가부시끼가이샤 filed Critical 후지쯔 가부시끼가이샤
2008-02-21 Publication of KR20080016454A publication Critical patent/KR20080016454A/en
2010-04-09 Publication of KR100952258B1 publication Critical patent/KR100952258B1/en
One of the objects of the present invention is to provide a system and procedure for effectively using a relay station. In the present invention, the wireless base station acquires the reception quality of the received signal received from the wireless base station without passing through the relay station, the reception quality received from the wireless base station through the relay station, and the acquired both. And a step of selecting a path to the wireless terminal based on the reception quality. In addition, a reception unit for receiving at a transmission timing at which transmission is made from a wireless terminal, which is notified by the wireless base station, a measurement unit for measuring the reception quality of the received signal obtained by the reception, and the measurement result are sent to the wireless base station. A relay station comprising a transmitting unit for transmitting is used.
Routing device, antenna, duplexer, packet buffer, MAP information generator, PDU buffer
Method of measuring reception quality at relay station and relay station and communication path selection method at wireless base station and wireless base station {RELAY STATION AND METHOD OF MEASURING RECEPTION
The present invention relates to a wireless terminal, a relay station, a wireless base station and a communication method between these stations using wireless communication. For example, when the relay station is added based on a wireless communication system specified in IEEE802.16, Particularly preferred.
Representative systems such as WCDMA, CDMA2000, and the like, are now being widely used in the world for wireless communication systems that communicate via wireless communication paths. In such a wireless communication system, a plurality of wireless base stations are provided in a service area, and the wireless terminal communicates with another communication device (communication terminal) via one wireless base station. At that time, the overlapping portion is set in the service area in which the adjacent radio base stations can communicate wirelessly, and with the deterioration of the radio environment, it is possible for the radio terminal to hand over to the adjacent radio base station.
Moreover, as a radio system, techniques, such as code division multiplexing, time division multiplexing, frequency multiplexing, OFDM, etc., are employ | adopted, for example, and it is common that a several wireless terminal can be connected to one wireless base station at the same time.
However, even if the wireless base station is in a service area capable of wireless communication, high-speed communication is often difficult because the wireless environment is not good at a place near the boundary of the area.
Therefore, a proposal has been proposed to arrange a relay station in a service area of a wireless base station so that the wireless terminal and the wireless base station can communicate wirelessly through the relay station.
In particular, in the 802.16j task group, the introduction of such a relay station (RS: Relay Station) is in full swing.
The above-described matters related to IEEE802.16 are disclosed in the following non-patent documents 1 and 2, for example.
[Non-Patent Document 1] IEEE Std802.16TM-2004
[Non-Patent Document 2] IEEE Std802.16eTM-2005
According to the background art described above, the wireless terminal can perform wireless communication with the wireless base station directly or through a relay station, but it is necessary to consider how to use the relay station in the wireless terminal.
Accordingly, one of the objects of the present invention is to provide a system and procedure for effectively using a relay station.
In addition, one of the objects of the present invention is that when a relay station is newly introduced, the radio terminal recognizes the presence of the relay station anew and causes direct communication with the relay station without causing a special communication with the relay station. It is possible to perform path selection control and path change control between communication paths.
In addition, the present invention is not limited to the above-mentioned objects, and the effects induced by the respective structures described in the detailed description for carrying out the invention described below, and also have an effect not obtained by the prior art, are also other object of the present invention. It can be positioned as one.
(1) In the present invention, a measurement unit for receiving a radio signal from a relay station at a measurement timing instructed by a radio base station, measuring a reception quality, and a transmission unit for transmitting the measurement result to reach the radio base station, A wireless terminal is featured.
(2) In the present invention, a transmission unit for transmitting a signal indicating a measurement timing of a reception quality to a wireless terminal, and a reception signal measured at the wireless terminal with respect to a radio signal transmitted to the wireless terminal from a relay station at the measurement timing. And a determining unit for determining whether to transmit a radio signal to the radio terminal through the relay station or to the radio terminal without passing through the relay station based on the quality.
(3) In the present invention, there is provided a reception unit for acquiring measurement timing at which the wireless terminal measures the reception quality of the radio signal, and a transmission unit for transmitting the radio signal at which the radio terminal can measure reception quality at the measurement timing. It uses a relay station characterized in that.
(4) In the present invention, the wireless base station acquires the reception quality of the received signal received from the wireless base station without passing through the relay station and the reception quality received from the wireless base station through one relay station; And a step of selecting a path to the wireless terminal based on the obtained reception quality of both parties.
(5) In the present invention, a reception unit that performs reception at a transmission timing at which transmission is performed from a wireless terminal notified by a wireless base station, a measurement unit that measures reception quality of a reception signal obtained by the reception, and the measurement result It uses a relay station characterized in that it comprises a transmitting unit for transmitting to the wireless base station.
(6) Preferably, the transmitting unit transmits to the radio base station also a deviation in the reception timing or a reception frequency detected by the reception.
(7) In the present invention, a transmitter for transmitting data for controlling transmission timing to a wireless terminal, and a signal transmitted from the wireless terminal in accordance with the control data without receiving through a relay station to measure quality, A quality measuring unit for obtaining reception quality information, a reception unit for receiving the reception quality information of the signal from the relay station that has received the signal, and obtaining second reception quality information, the first reception quality information, and the second reception quality information. And a determining unit for selecting a communication path to the wireless terminal based on the wireless base station.
(8) Preferably, when the relay station receives the shift in the reception timing or the shift in the reception frequency detected by the relay station by the reception of the signal, the relay station is included in the communication path selected by the determination unit. The transmitter transmits the deviation of the reception timing or the deviation of the reception frequency to the wireless terminal.
(9) In the present invention, a step of receiving a signal from a wireless terminal without passing through a relay station, measuring quality, obtaining first reception quality information, and receiving reception quality information of the signal from the relay station receiving the signal; Obtaining a second reception quality information, and selecting a communication path to the wireless terminal based on the first reception quality information and the second reception quality information.
According to the present invention, the relay station can be effectively used.
According to the present invention, when a relay station is newly introduced, a path is selected between a communication path and a direct communication path through the relay station without causing the wireless terminal to newly recognize the existence of the relay station and to perform special communication with the relay station. Control or route change control can be performed.
It is necessary to synchronize when a wireless terminal receives a signal by radio from a wireless base station. Therefore, each radio base station transmits a signal for synchronization in its service area. For example, the synchronization signal (synchronization signal) can be a different preamble signal in each radio base station. The wireless terminal stores a plurality of types of preamble signals in advance, and can select, as the wireless base station at the communication destination, the one with the best reception quality (for example, reception level) among the patterns.
As a radio system, for example, when OFDM is used, the radio base station allocates transmission data to each subcarrier and transmits using a plurality of subcarriers, and the preamble is assigned to each subcarrier in a predetermined pattern. Can be sent. The wireless terminal can receive the predetermined combination of subcarriers, match the known preamble signals, and synchronize with the wireless base station that transmits the best preamble.
The radio base station configures a frame based on the synchronization signal and transmits the signal. The wireless terminal establishes frame synchronization using the synchronization signal, and receives mapping information (data for controlling the transmission or reception operation of the wireless terminal; MAP data) of data based on the synchronization signal. For example, MAP data is placed immediately after the synchronization signal.
In the MAP data, timing, channel information, and modulation method when mapping data to a physical channel (downlink channel (channel from the wireless base station to the wireless terminal side) and uplink channel (channel from the wireless terminal side to the wireless base station side)) , A coding scheme, a coding rate, and the like, and the radio frame has a structure corresponding to MAP data. Further, a wireless terminal can be designated using identification information of the terminal, and a physical channel can be designated for each wireless terminal. Of course, mapping information may be transmitted to a plurality of wireless terminals (for example, all of the wireless terminals in a service area formed by one wireless base station) for transmitting and receiving a predetermined signal without specifically designating the wireless terminal. have.
Therefore, data configured in correspondence with the terminal ID using parameters required for reception (transmission) such as reception (transmission) timing and reception (transmission) channel (reception (transmission) subchannel pattern information) can be used as an example of MAP data. .
The wireless terminal receives the radio signal by the reception timing and reception channel designated by the MAP data, and transmits the radio signal by the transmission timing and transmission channel designated by the MAP data. Thereby, wireless communication can be performed directly (without a relay station) with a radio base station.
On the other hand, the relay station similarly receives a synchronization signal from the radio base station and establishes synchronization. Then, MAP data is received on the basis of the synchronization signal, and transmission data to the wireless terminal is transmitted in accordance with parameters necessary for transmission such as transmission timing specified by the MAP data, transmission channel (transmission subchannel pattern information), and the like. . In addition, transmission data to a wireless terminal can be obtained using a communication link (MMR link) between the radio base station and the relay station. The relay station may also acquire parameters such as transmission timing, channel, etc. designated by the MAP data in advance using the MMR link.
That is, the relay station receives the radio signal in front of the own station by the reception timing specified by the MAP data or the MMR link and the reception channel, and transmits the radio signal to be transmitted from the own station by the transmission timing specified by the MAP data and the transmission channel. . In addition, the MMR link is communication between the wireless base station and the relay station, and the wireless terminal does not need to receive it.
In addition, it is assumed that the relay station does not retransmit the MAP data to the wireless terminal. This means that the MAP data has a small amount of information and can be repeatedly transmitted to general transmission data (user data), and it is considered that it is easy to reach the wireless terminal with respect to the transmission data by increasing the transmission power by that portion or transmitting at a low speed. Because.
The radio terminal can receive the transmission data retransmitted from the relay station by receiving the MAP data directly from the radio base station and thereby receiving the radio signal.
Therefore, the radio terminal can also receive data directly from the radio base station, and the relay station can also receive data from the relay station once received from the radio base station.
In addition, the wireless terminal only receives and transmits in accordance with MAP data transmitted from the wireless base station, and does not need to recognize that data is transmitted and received through the relay station.
As described above, by using the relay station, there are a plurality of candidates for the transmission / reception path of the wireless terminal, and the wireless communication of the wireless terminal can be supported near the boundary of the service area of the wireless base station.
Here, it is preferable that the relay station does not retransmit the synchronization signal periodically transmitted from the radio base station. In other words, if the relay station retransmits the synchronization signal, the wireless terminal receives the synchronization signal from the relay station, synchronizes with the relay station, searches for the MAP data based on the synchronization signal, but does not find it. . In addition, there is a need to recognize the existence of a separate station different from the radio base station.
Next, how the wireless terminal should use the relay station will be described.
In order to select a wireless base station from which the wireless terminal can obtain a good reception quality among a plurality of wireless base stations, a synchronization signal (for example, a preamble signal or a pilot signal) transmitted from each wireless base station may be used.
By the way, when the relay station receives a synchronization signal (for example, a preamble) periodically transmitted from the radio base station, but does not retransmit the preamble, the relay station cannot select a preferred side between the relay station and the radio base station.
Therefore, the wireless terminal can acquire the timing at which the radio signal is transmitted from the relay station based on the data (MAP data, control data) transmitted from the radio base station, and can measure the reception quality of the radio signal from the relay station according to the acquired timing. have.
Hereinafter, the detailed structure and operation | movement of each part are demonstrated using drawing.
1 shows the configuration of a wireless communication system in the first embodiment. In the figure, reference numeral 1 denotes a routing device, reference numeral 2 denotes a radio base station (BS), reference numeral 3 denotes a relay station (RS), and reference numeral 4 denotes a wireless terminal (T). As the wireless terminal 4, any one of a so-called MS (Mobile Station) suitable for mobile use and a wireless device suitable for fixed use can be used.
Here, the wireless terminal 4 can also perform wireless communication with the wireless base station 2 directly (without passing through the relay station) within the service area of the wireless base station 2, and also within the service area of the relay station 3. Wireless communication can be performed with the radio base station 2 via the relay station 3. The relay station 3 is provided in one or more in the service area of the radio base station 2 and can perform radio communication with the radio terminal 4.
The wireless base station 2 is connected to the routing device 1, receives the data received from the wireless terminal 4, sends the data to the routing device 1, and conversely, the routing device 1. Control to transmit the data received from the wireless terminal 4 to the wireless terminal 4 is performed. The routing device 1 is connected to a plurality of radio base stations and performs routing so that data arrives at the destination by sending data received from the radio base station 2 to another routing device or another radio base station. Preferably, the radio base station 2 converts the data into a packet format and then transmits the data to the routing device. In order to be accessible from the routing device 1, a database storing a location registration area of the wireless terminal (ie, information on the wireless terminal in each area composed of a plurality of wireless base stations), a service type, and the like are arranged. Therefore, it is desirable for the routing device to obtain this information.
Next, the configuration of the radio base station 2 will be described in more detail with reference to FIG. 2.
2 is a diagram illustrating a configuration of the radio base station 2. As shown in FIG.
In the figure, reference numeral 10 denotes an antenna for transmitting and receiving a radio signal between the relay station 3 and the wireless terminal 4, reference numeral 11 denotes a duplexer for sharing the antenna 10 in a transceiver system, and reference numeral 12 denotes a receiver. 13 is a demodulator for demodulating a received signal, 14 is a decoder for decoding a demodulated received signal, 15 is a control data extracted from the decoded data, and transmitted to the communication path determiner 17; At the same time, a control data extracting unit for transmitting other data such as user data to the packet generating unit 16, and 16 denotes a packet generating unit for packetizing the data transmitted from the control data extracting unit and handing it to the NW interface unit.
Reference numeral 17 denotes a communication path determining unit for determining a communication path, and it is preferable that the wireless terminal 4 directly communicate with the wireless base station 2 on the basis of the extracted control data. Decide if it is preferable to communicate. Reference numeral 18 denotes a communication path management unit that manages and stores the determined communication path for each wireless terminal.
Reference numeral 19 generates measurement control data for causing the wireless terminal 4 to measure the reception quality according to the control of the communication path determining unit 17, and generates control data for supplying it to the MAP information generation unit 23. Represents wealth. In that case, the measurement control data can include identification information of the wireless terminal 4, measurement timing of reception quality, and channel information.
Reference numeral 20 denotes an interface unit forming an interface (herein, packet communication) with the routing device 1, and reference numeral 21 identifies an IP address included in the packet data received from the NW interface unit 20. The destination wireless terminal 4 is specified based on the IP address data (for example, the correspondence between the IP address data and the ID of the wireless terminal 4 is stored and the ID of the corresponding wireless terminal 4 is obtained). At the same time, the QOS (similarly stored in association with the ID) information corresponding to the ID is acquired, the ID and QOS information is supplied to the MAP information generation unit 23, and a band allocation request is made. The NW interface unit 20 The packet data passed from the program is stored in the packet buffer unit 22.
Reference numeral 23 denotes a MAP information generation unit. Upon receiving a band allocation request, reference numeral 23 specifies a communication path by searching with the ID of the wireless terminal 4 that obtained the communication path management table 18 as a key, and determines a mapping area according to QOS. Instructs the PDU generation unit 24 to configure a frame accordingly. At that time, the data to be transmitted is read from the packet buffer unit 22 and delivered to the PDU generation unit 24 together with the MAP data. In addition, in order to establish a communication link (MMR link) between the radio base station 2 and the relay station 3, similarly, the MAP data includes identification information, transmission / reception timing, and channel of the relay station 3 as a communication target. The data can also be transmitted to the relay station from the timing and channel.
When the MAP information generation unit 23 receives the measurement control data from the control data generation unit 19, the MAP information generation unit 23 secures the transmission timing and channel necessary for the transmission of the data, and then secures the secured transmission timing and channel. The MAP data shown is generated and delivered to the PDU generating unit 24 together with the measurement control data, thereby transmitting the measurement control data. The MAP information generation unit 23 then controls the PDU generation unit 24 so that a radio signal is transmitted from the radio base station 2 or the relay station 3 in the measurement timing and channel specified by the measurement control data. In addition, when the radio base station 2 periodically designates a radio signal (for example, a preamble) to be transmitted as a measurement target, the radio base station 2 does not need to newly transmit a radio signal for the purpose of measuring the reception quality. do.
However, for the relay station 3, a radio signal needs to be transmitted at least in the measurement period. Therefore, the MAP information generation unit 23 includes the measurement timing and channel information specified by the measurement control data for the wireless terminal 4 in the MAP data, and uses the MMR link to perform the relay station within the measurement period. Control to transmit the signal to be transmitted to the relay station 3 in the area of (3). As a signal to be transmitted within the measurement period, for example, a pilot signal can be exemplified. However, by setting the user data including the pilot signal, the radio base station 2 can transmit meaningful data that can be used in addition to the reception quality measurement. have. The signal transmitted within the measurement period may be a signal transmitted to a specific wireless terminal (for example, T (4-1)) in the area, a signal transmitted to a wireless terminal different from the wireless terminal performing measurement, or It is also possible to set the signal to be transmitted to the general wireless terminal in the area instead of the specific wireless terminal.
Reference numeral 24 denotes a PDU generation unit, generates a PDU so that MAP data, transmission data (including measurement control data) and the like are stored in each area of a radio frame formed on the basis of a synchronization signal (preamble), and encoded. It sends to the part 25. Reference numeral 25 denotes an encoder, reference numeral 26 denotes a modulator, and reference numeral 27 denotes a transmitter, and in order, the PDU data is modulated after performing encoding processing such as error correction encoding, and the antenna 10 is transmitted from the transmitter 27. Is transmitted as a wireless signal.
3 is a diagram illustrating the configuration of the relay station 3.
In the figure, reference numeral 30 denotes an antenna for transmitting and receiving radio signals between the wireless base station 2 and the wireless terminal 4, reference numeral 31 denotes a duplexer for sharing the antenna 10 in transmission and reception, and reference numeral 32 denotes a receiving unit. Reference numeral 33 is a demodulator for demodulating a received signal, reference numeral 34 is a decoder for decoding a demodulated received signal, and reference numeral 35 is a MAP by extracting MAP data (received from the wireless base station 2) from the decoded data. The wireless terminal 4 received from the wireless terminal 2 while supplying the MAP data (received from the wireless base station 2) and supplying to the MAP information analyzing unit 36 while supplying to the information analyzing unit 36. The control data extraction section 35 for transmitting the above data to the PDU buffer section 37 is shown. Similarly, when a radio signal is received from the radio terminal 4, the reception data is transmitted to the PDU buffer unit 37 for transmission to the radio base station 2. FIG.
Reference numeral 37 denotes a PDU buffer unit, and the radio base station 2 is in accordance with the transmission timing and channel notified from the radio base station 2 by the MAP data analyzed by the MAP information analysis unit 36 or the data received through the MMR link. The encoder 38, the modulator 29, and the like are controlled so as to transmit corresponding data to the wireless terminal 4 received from the &lt; RTI ID = 0.0 &gt; In addition, data and measurement control data directed to the wireless terminal 4 are received via a communication link (MMR link) formed between the wireless base station 2 and the relay station 3. In addition, since the MAP data transmitted from the radio base station 2 includes the identification information of the relay station 3, the transmission timing, and the channel information, the relay station 3 receives the radio signal at the specified timing and channel. The transmission of data or the like is performed between the (2) -relay stations 3 (the upward direction is similarly defined by the MAP data).
Reference numeral 38 denotes an encoding unit, and reference numeral 39 denotes a modulation unit, respectively. The transmission data and measurement control data from the PDU buffer unit 37 are encoded, and the user data and measurement control in the transmission timing and channel acquired by the MAP information analysis unit. Modulation processing is carried out so as to transmit data, or is passed to the transmission unit 40.
Reference numeral 40 denotes a transmission unit, and transmits a transmission signal as a radio signal to the radio terminal 4 and the radio base station 2 via the antenna 30.
4 is a diagram illustrating a configuration of the wireless terminal 4.
In the figure, reference numeral 50 denotes an antenna for transmitting and receiving radio signals between the relay station 3 and the radio base station 2, reference numeral 51 denotes a duplexer for sharing the antenna 50 in transmission and reception, and reference numeral 52 denotes a receiving unit. Is a demodulator for demodulating the received signal, 54 is a decoder for decoding the demodulated received signal, and 55 is control data extracted from the decoded data, and when the control data is measurement control data, It supplies to the measurement instruction | indication analysis part 56, if it is MAP data, it supplies to the MAP information analysis part 57, and delivers other data (user data) to the data processing part 58. As shown in FIG. Reference numeral 58 denotes a data processing unit, which performs display processing, audio output processing, and the like of various data included in the received data.
In addition, from the data processing unit 58, user data desired to be transmitted to the communication destination device is input to the PDU buffer unit 61.
Reference numeral 59 denotes a reception quality measurement unit, and performs measurement processing of reception quality on the measurement timing and measurement channel obtained by the analysis result of the measurement instruction analysis unit 56. For example, the carrier to interference and noise ratio (CINR) of the signal received by the receiver 52 is measured and delivered to the control data generator 60. In addition, the reception quality measuring unit 59 measures not only the reception signal from the relay station 3 but also the reception quality of the signal directly received from the radio base station 2. For example, it may be measured for the sync signal (preamble) part or for the other part. Either way, the measurement timing or the like can be designated by the measurement control data.
The control data generation unit 60 obtains the measured reception quality information (reception quality for the wireless base station 2 and the relay station 3) and supplies it to the PDU buffer unit 61 as control data.
Reference numeral 61 denotes a PDU buffer unit, and the encoder 62 transmits the transmission data from the data processing unit 58 and the reception quality information from the control data generation unit 60 in the transmission timing and transmission channel designated by the MAP data. And the modulator 63.
Reference numeral 62 denotes an encoding unit, and reference numeral 63 denotes a modulation unit. Encoding and modulation processing are performed on the transmission data so that transmission data from the PDU buffer unit 61 is transmitted on the transmission timing and transmission channel specified by the MAP information. do.
The transmitter 64 transmits a radio signal through the antenna 50.
Next, one draft of the radio frame format will be described, and the communication procedure in the system will be described in detail. In addition, although the radio frame format corresponding to IEEE Std802.16d and e is taken as an example here, an embodiment is not limited to this.
5 is a diagram illustrating an example of a frame format of a radio signal transmitted and received between a radio base station, a relay station, and a radio terminal. In addition, it is assumed that BS 2-1, RS 3-1, RS 3-2, T 4-1, and T 4-2 are in the arrangement relationship shown in FIG.
By the way, in the figure, Tx and Rx mean transmission and reception, respectively. Therefore, BS 2 transmits DL / UL MAP, MMR1, MMR2 in order with preamble P as the head of the frame. The preamble is a predetermined known pattern transmitted by the wireless terminal 4 and the relay station 3 to enable synchronization with the wireless base station 2. When OFDM is used, a signal of the predetermined pattern is transmitted to each subchannel. It is to be transmitted through.
Subsequent to transmission of the preamble, DL / UL MAP is an area for storing control data (MAP data) for notifying the relay station 3 and the wireless terminal 4 of the transmission reception timing and the transmission / reception channel. For example, transmission timing and transmission channel information of MMR1 and MMR2 transmitted as an MMR link to a relay station from a radio base station via a downlink channel, and data transmission to the radio terminals 4-1 and 4-2 (T4-1). MAP data (transmission or information) indicating timing and transmission channel information for performing T4-2) and information indicating at what timing and in which channel (MMR1, MMR2, T4-1, and T4-2) to transmit through the uplink channel. Information indicating how to map for reception).
Therefore, each of the relay station 3 and the wireless terminal 4 receives the preamble P directly from the wireless base station 2, thereby synchronizing with the frame timing of the wireless base station 2, and receiving the DL / UL MAP based on that. Then, it determines what timing and channel to transmit and receive, and receives at the corresponding timing and channel.
In the example of the figure, the RS 3-1 analyzes the DL / UL MAP and receives the MMR1 including the message in front of itself and transmits it to the wireless terminal 4-1 in the transmission of T4-1. Data is received from the wireless base station 2. Similarly, it is determined that the transmission timing of data to the wireless terminal 4-1 designated by the DL / UL MAP is T4-1 in the figure, and the data received by MMR1 is transmitted at the timing of T4-1.
On the other hand, the wireless terminal 4-1 synchronizes with the wireless base station 2 by the preamble transmitted from the wireless base station 2, and interprets the DL / UL MAP, thereby at a specified timing T4-1 and channel. Since it recognizes that data is being transmitted, it operates to receive the data.
Therefore, the wireless terminal 4 can receive data without being aware of the source of data transmission (without distinguishing whether it is the wireless base station 2 or the RS 3).
In this frame configuration example, a period during which transmission is performed for RS and T from BS 2, a period during which transmission is performed for RS from BS 2 (MMR period), and T from RS 3-1 are used. The period in which transmission is performed with respect to and the period during which transmission is performed with respect to T from the RS 3-2 are separated in time. In addition, the upper direction is also separated in time from the lower direction, and similarly, each transmission period of T and RS is also separated in time. Although the transmission and reception of each section are separated by time division (the same frequency band can be used), other separation methods such as frequency separation may be employed.
Next, the path selection control in the case of using this frame structure will be described.
First, the wireless terminal 4 executes a network entry by turning on the power. That is, by receiving the preamble transmitted from the wireless base station 2, the existence of the wireless base station 2 is recognized. According to the network entry procedure, wireless communication is performed with the wireless base station 2 according to the communication timing and channel allowed in the MAP (for example, Ranging generated by the control data generation unit 60 in the RNG of FIG. 7). The process is started by transmitting a signal (ranging code, ranging request). The wireless terminal 4 registers itself with the wireless base station 2 as the service target wireless terminal, and registers its own capability information (Capability information) with the wireless base station 2. That is, the storage unit of the communication path management unit 18 can be stored in association with the wireless terminal ID like other data.
At this time, the wireless terminal 4 may perform a network entry by wirelessly communicating with the wireless base station 2 via the relay station 3. That is, when the wireless terminal transmits a Ranging signal at T (4-1) in the uplink transmission period, but is not received by the wireless base station 2, the relay station 3-1 which has received the Ranging signal receives the MMR1. By the Ranging signal can be delivered to the wireless base station (2). Since the MAP information analysis unit 36 of the relay station 3 has grasped the transmission timing of the RNG by receiving the MAP data from the radio base station 2, control of the reception system such as the reception unit 32 to receive it. Can be transmitted to the wireless base station 2 by receiving a Ranging signal and supplying it to the PDU buffer unit.
The communication path management unit 18 of the radio base station 2 directly connects the communication path with the ID of the radio terminal 4 when the reception unit 12 receives the Ranging signal from the radio terminal 4. The settings are registered as "communication directly (not via a relay station)". On the other hand, when a Ranging signal is received through the MMR link (communication link through the relay station) (in this case, the relay station 3-1), the setting is registered as "communication through the relay station 3-1." The radio base station 2 can easily determine whether it was received directly or through which relay station 3 based on the reception timing based on the transmitted MAP data. Of course, you may judge based on ID contained in data.
Upon completion of the network entry, the wireless base station 2 recognizes that the wireless terminal 4 (4-1) exists under management as the terminal to be communicated with, and thus whether or not the current state (communication path) is desirable. To judge. That is, the radio base station 2 operates the communication path determining unit 17 to execute the communication path selection process.
First, the communication path determination unit 17 notifies the control data generation unit 19 to generate measurement control data for the wireless terminal 4 that has made a network entry. Here, the reception quality is first measured for the direct communication path between the radio base station 2 and the radio terminal 4, and then the reception quality is measured for the communication path with the radio terminal 4 through the relay station 3. Shall be. This order may be reversed, and the communication path already set and registered by the communication path management unit 18 may be the first reception quality measurement target. In addition, when there exist a plurality of relay stations 3, the reception quality at the time of passing through each of the some relay station 3 can also be measured in order. In that case, the measurement control data may also be generated and transmitted a plurality of times corresponding to each relay station 3. In addition, the identification information of the relay station 3 under the management of the radio base station 2 (in the service area) is managed and stored in the communication path determining unit 17.
By the way, first, in order to measure the reception quality with respect to the direct communication path between the radio base station 2 and the radio terminal 4-1, the control data generation unit 19 receives the radio signal from the radio base station 2 in advance. The MAP information generation unit 23 is controlled to transmit the indicated measurement control data using the transmission period as the measurement period. Therefore, the MAP information generation unit 23 includes the transmission timing of the measurement control data, the channel information, and the identification information of the wireless terminal 4-1 in the MAP data, and the measurement control data ( A) control to transmit.
However, when setting and registering the relay station 3-1 as a path in the communication path management unit 18, the radio base station 2 transmits measurement control data to the relay station 3-1 by the MMR1 link. Can be transmitted from the relay station 3-1 to the wireless terminal 4-1 via the transmission timing and channel specified by the MAP data.
The wireless terminal 4-1 analyzes the measurement control data in the measurement instruction analyzer 56 and from the radio base station 2 with respect to the measurement timing indicated by the measurement data using the reception quality measuring unit 59. Measure the reception quality of the received signal. The measurement timing and channel may be notified to the radio terminal 4-1 again by MAP data.
The wireless terminal 4-1 delivers the measured reception quality information to the control data generation unit 60 and transmits it on the transmission timing and channel designated by the MAP data (or measurement control data).
The radio base station 2 acquires the reception quality information (reception quality 1) measured directly or through the relay station 3-1, and supplies it to the communication path determination unit 17.
Next, the control data generation unit 19 of the radio base station 2 similarly generates measurement control data B in order to measure the reception quality of the communication path with the radio terminal via the relay station 3-1. In the same manner as described above, the wireless terminal 4-1 is transmitted. In addition, measurement control data (A) and (B) can also be included in one measurement control data. In this case, the number of transmissions of the measurement control data can be reduced.
However, this time, the relay station 3-1 needs to transmit a radio signal at the measurement timing. Thus, for example, by receiving the measurement control data from the relay station 3-1, the control data extracting unit 35 recognizes that measurement is necessary, and transmits a known signal such as a pilot signal at the measurement timing. The unit 37 is controlled. The signal to be transmitted here may be generated by the relay station 3 (generated by the control data generating unit 42 in accordance with the detection of the measurement control data by the control data extracting unit 35), or sent to the wireless base station 2. May be received via an MMR link.
Alternatively, a signal is transmitted to the wireless terminal under management (4-1 or 4-2 or not specified wireless terminal in general) on the measurement timing, the same timing and channel as the MAP data from the wireless base station 2. The MAP information analysis unit 36 recognizes this, and receives a signal (a signal including a known signal such as a pilot signal) to be transmitted in the timing and channel through the MMR1 link. By transmitting the signal at a corresponding timing and channel, the radio signal is transmitted from the relay station 3-1 in the period in which the reception quality is measured in the radio terminal 4-1.
Therefore, it can be said that the measurement control data or the MAP data is responsible for receiving the radio signal from the relay station 3-1 to the radio terminal 4 and notifying the period during which the reception quality can be measured.
The wireless terminal 4-1 delivers the measured reception quality to the control data generation unit 60, and transmits it on the transmission timing and channel designated by the MAP data (or measurement control data).
The radio base station 2 acquires the reception quality information (reception quality 2) measured directly or through the relay station 3-1, and supplies it to the communication path determination unit 17.
In addition to or separately from the reception quality information from the radio terminal 4-1, the relay station 3-1 determines MMR1 as the reception quality (reception quality 3) of the radio signal received from the radio base station 2. Report to the wireless base station 2 through. As the measurement object, a preamble may be used, or the quality of a signal received as data to be transmitted to the radio terminal 4-1 in the measurement period from the radio base station 2 through MMR1 may be used. In addition, the measurement of the reception quality in the relay station 3-1 may be performed separately separately (using the reception quality measuring unit 41 in FIG. 3) and regularly reported to the radio base station 2 via MMR1. do. This report can also be shared with adaptive modulation control in MMR and adaptive control of coding rate change. For example, a CQI indicating the reception quality from the radio base station 2 at the relay station 3 transmitted from the relay station 3 to the radio base station 2 can be used. In addition, CQI is changed corresponding to CINR.
By the way, the communication path determining unit 17 of the wireless base station 2 receives two types of received quality information (quality for the received signal directly from the wireless base station 2, quality of the received signal through the relay station 3). ), The path of the better quality is selected. At this time, the quality may use, for example, a radio quality evaluation parameter such as CINR. The communication path determination unit 17 notifies the communication path management unit 18 of the result of the selection in correspondence with the wireless terminal 4-1, and causes management registration.
In the comparison, the reception quality 1 and 2 may be compared with each other, or the reception quality 1 may be compared with the synthesis (simple average or the like) of the reception quality 2 and the reception quality 3. Either way, the good reception quality may be selected.
In addition, the communication path determination unit 17 may use the use efficiency of the band as a comparison reference. For example, when QPSK is applied to direct communication between the wireless base station 2 and the wireless terminal 4, and the coding rate is 1/2, the efficiency is estimated to be 1 bit / symbol. On the other hand, the communication between the radio base station 2 and the relay station 3-1 is 64QAM, the coding rate is 1/2, the 64QAM between the relay station 3-1 and the wireless terminal 4, and the coding rate 1/2 is When applied, it is 3 bits / symbol on each link, but since two transmissions are required for the same data transmission, the practical efficiency is estimated at 1.5 bits / symbol, and as a path, the method through the relay station is good. By judging, the route via the relay station 3-1 is selected as the path.
Similarly, when the communication between the radio base station 2 and the relay station 3 is 64QAM and the coding rate is 1/2, the 16QAM between the relay station 3 and the wireless terminal 4 and the coding rate 1/2 is applied. 3bit / symbol and 2bit / symbol on each link, considering two transmissions, it is finally evaluated as 1.2bit / symbol. As a route, it is determined that the efficiency through the relay station is more efficient. Choose.
6 is a flowchart for explaining a selection algorithm.
As shown in the figure, first, the radio base station 2 receives a quality measurement result from the radio terminal 4. Here, it is assumed that at least the reception quality for the direct communication between the radio base station 2 and the radio terminal 4 and the communication through the relay stations 2-1 and 2-2 are received.
Next, the radio base station 2 and the relay station 3 communicate a transmission method (it is possible to transmit a radio signal by using an adaptive modulation control (change modulation method or the like) or change the coding rate) according to the reception quality). By using the table reference stored in the decision unit 17, the bandwidth use efficiency described above is obtained, and it is determined whether the path having the highest use efficiency is direct communication. Here, in the case of YES, the radio base station 2 determines that direct communication with the radio base station 2 is optimal, and selects the path.
On the other hand, in the case of NO, the route via the relay station which becomes the best use efficiency is specified, and the route is selected. In addition, it is also possible to select a path on the side where the QOS can be guaranteed on the condition of the runaway state or whether the QOS can be guaranteed.
Moreover, as an evaluation method, transmission power can also be added.
That is, there are cases where the transmission powers from the radio base station 2 and the relay station 3 are different from each other. In this case, it is preferable to add the transmission powers.
For example, the best path may be selected by comparing the normalized reception quality (Mi-NidB) obtained by subtracting each transmission power (NidMm) from each obtained reception quality (MidB) as the reception quality.
In addition, at this time, the transmission power may be added in such a way that there is no difference between the transmission power of the relay station or the wireless base station and the transmission power between the selected relay station or the wireless base station with respect to the best received acquisition quality.
In addition, the selected communication path is managed and stored in the communication path management unit 18. Then, when the radio base station 2 transmits the radio signal to the radio terminal 4-1 thereafter, the radio base station 2 refers to it and controls to transmit data through the stored path. That is, in the case where the radio base station 2 directly transmits, it is not necessary to send the transmission data to the relay terminal 4-1 to the relay station using the MMR link, but is directly transmitted by the reception timing and channel specified by the MAP data. do. When transmitting through the relay station 3, the radio base station 2 designates a reception timing and a channel according to MAP data, and transmits data to be transmitted on the timing and channel using the MMR link. 3) to be transmitted from the relay station 3 to the wireless terminal 4-1.
In addition, the communication path can be determined by setting the communication path determining unit 17 in the wireless terminal 4, in which case, the communication path management unit 18 of the wireless base station 2 is used as the control data. ) Is sent.
In the first embodiment, the reception quality is measured by the wireless terminal 4 or the like. Here, the reception quality is measured by the wireless base station 2 or the like.
In addition, in this embodiment, it demonstrates focusing on BS (2-1), RS (3-1), T (4-1), T (4-3) in FIG.
The structure of each apparatus can be made substantially the same as the structure of FIGS.
As a unit to be added, in Fig. 2 showing the configuration of the radio base station 2, the reception quality measurement unit 28 for measuring the reception quality and the reception quality measurement in Fig. 3 showing the configuration of the relay station 3 are measured. A reception data measuring section 41 for generating a control data including the measured reception quality and directing the transmission data to a transmission system for transmission to the wireless base station 2; In FIG. 4, a measurement signal generation unit for generating a measurement signal (for example, a ranging signal) necessary for enabling measurement of reception quality at the radio base station 2 and the relay station 3, and delivering the signal to a transmission system. (65) is mentioned as an example.
On the other hand, as a unit which can be deleted, in FIG. 4 which shows a wireless terminal, the measurement instruction | indication analysis part 56, the reception quality measuring part 59, and the control data generation part 60 are mentioned.
Next, a radio frame format used for radio communication between the BS 2, the RS 3-1, and the T 4-1, 4-3 will be described with reference to FIG.
Tx and Rx denote transmission and reception, respectively, P denotes a preamble, DL / UL MAP denotes MAP data, and MMR1 denotes a communication period used for communication between the BS 2 and the RS 3-1, and T4-3. Indicates a communication period used for direct communication between the BS 2 and the T 4-3, and T4-1 communicates with the T 4-1 via the RS 3-1. Indicates a communication period.
In addition, RNG represents the ranging signal transmitted from the radio terminals T (4-1, 4-3). The Ranging signal is a known signal and is received at the radio base station 2 or the relay station 3, and at the reception system of the receiving device, reception timing shifts (phase shifts), reception frequency shifts, and necessary increase / decrease information of transmission power are obtained. It is reported to the radio base station 2 as adjustment information. In addition, the Ranging signal is generated by the measurement signal generation unit 65.
The radio base station 2 notifies the radio terminal 4 of the obtained adjustment information. However, when there is a relay station 3 managed and set as a path by the communication path manager 18, Adjustment information from the relay station is adopted. When the relay station 3 is not included in the path, the radio base station 2 measures in its own receiver and transmits the obtained adjustment information to the radio terminal 4.
In addition, the RNG can be performed regularly after entry, and the cycle and timing can be instructed by the transmission of control data from the radio base station 2.
On the other hand, CQI is a transmission period for reporting the result of the wireless terminal measuring reception quality with respect to known signals such as a preamble or a pilot signal. The timing and channel are defined by UL MAP.
Next, the path selection process after entry will be described with reference to FIG. 8. Since the entry has already been completed, the wireless terminal 4 is registered in the communication path management unit 18 with its existence in the wireless base station 2.
As shown in the figure, the RSs 3-1 and 3-2 periodically transmit channel performance information to the BS 2. This is to control the radio quality between the relay station and the radio base station, for example, by measuring the reception quality of a known signal such as a preamble by the reception quality measuring unit 41 and indicating the measurement result by the control data generation unit 42. Data is generated and reported to the radio base station 2.
In addition, the radio base station 2 can adaptively change the modulation scheme and encoding rate between the radio base station 2 and the relay station 3 in accordance with the reported channel performance information. That is, the radio base station 2 acquires this channel performance information by the control data extracting unit 15, and determines the coding rate in the encoder 25 and the modulation method in the modulator 26 according to the reception quality. You can change it dynamically. The relay station 3 can also obtain channel performance information from the radio base station 2 and perform the same transmission control.
By the way, since the T 4-1 communicates with the radio base station 2 via the RS 3-1, the preamble, UL / DL MAP, and the like are received directly from the radio base station 2, Is received via the RS 3-1 (see FIG. 7 T (4-1)). In addition, the purpose of forming a communication path through the RS 3-1 is registered in the communication path management unit 18.
On the other hand, the radio terminal 4-1 transmits the ranging signal in the RNG timing and channel designated by the UL MAP. The ranging signal is generated and transmitted by the control data generation unit 60 based on the control of the MAP information analysis unit 57. Here, when the RS 3-2 also exists in an area capable of receiving a ranging signal from the wireless terminal 4-1, the ranging signal is RS 3-1, RS 3-2, BS. (2) All have been reached, and are received by the reception units 12 and 32.
Therefore, in this embodiment, the RS 3-1 and RS 3-2 each receive a ranging signal, measure the reception quality by the reception quality measuring unit 41, and control data generation unit 42. The measurement result is delivered to the BS 2 together with the ID of the radio terminal 4-1 as ranging information. At this time, the reception timing shift (phase shift), the reception frequency shift, and necessary increase / decrease information of the transmission power are obtained from the reception system, and the control data generation unit 42 generates and reports the adjustment information including the contents thereof.
Accordingly, the communication path determining unit 17 of BS2 receives the reception quality of the ranging signal measured by the reception quality measuring unit 28, and the ranging signal acquired from the RS 3-1 and RS 3-2. The reception paths included in the control are compared to determine the best path, and the communication path management unit 18 manages and stores the received paths. As the route determination method, various methods described in the first embodiment can be adopted.
Of course, the wireless base station 2 measures the reception quality by the reception quality measuring unit 28 for MMR1 and 2, which are respective communication links with the RSs 3-1 and 3-2, respectively. 1) The reception quality can also be added to the path via the RS 3-2. That is, similarly to the first embodiment, the reception quality of the uplink from the wireless terminal 4-1 to the RSs 3-1 and 3-2, and the wireless base station 2 from the RSs 3-1 and RS-3-2. It is also possible to take a simple average of the quality of the uplink to and compare it with the line quality of the uplink direct communication from the radio terminal 4 to the radio base station 2. Of course, as mentioned above, the best thing of the band | band | band efficiency to be used can also be calculated | required by calculation.
If the best path is a path through a relay station (here referred to as RS 3-2), subsequent transmission control is executed so that data is transmitted from the relay station 3-2 to the radio terminal 4.
That is, the MAP information generation unit 23 notifies the radio terminal 4 and the relay station 3-2 of the transmission timing and channel by the MAP data, and transmits the information to the relay station 3-2 via the MMR2 link. Send the data to be transmitted at the timing. As a result, data is transmitted to the wireless terminal 4 via the relay station 3-2.
The control data generation unit 19 also transmits adjustment information to the wireless terminal 4 as a response to the ranging request. At this time, the adjustment information is employed as the adjustment information acquired from the relay station 3-2 included in the path selected by the communication path determining unit 17. In addition, this adjustment information may be transmitted directly from the radio base station 2 to the radio terminal 4-1, and may be included in the relay station 3 previously included in the route or in the route newly selected this time. It can also transmit via the relay station 3-2.
Then, it is assumed that data is transmitted to the wireless terminal via the relay station 3-2 until the path is switched next.
9 shows a path selection flow.
First, the radio base station 2 first determines whether a ranging signal has been received.
Here, in the case of receiving, it is determined whether or not the reception quality is received from the relay station 3.
In this case, when it is not received, it is determined that the path via the relay station 3 cannot be selected, and a path for direct communication is selected.
In the case of reception, the modulation scheme and the coding rate corresponding to the respective reception quality information are determined, and the band utilization efficiency is obtained, respectively.
Based on the obtained band utilization efficiency information, it is determined whether the path of direct communication is the best, and if it is determined that it is the best, the path of direct communication is selected.
On the other hand, if it is judged that direct communication is not the best, the relay station 3 included in the path of the best band use efficiency is identified and selected.
By the way, in the first step, when the radio base station does not receive the ranging signal, it is determined whether or not the reception quality information has been received from the relay station 3.
In the case where it is determined that there is no reception, the process returns to the first step and the reception of the ranging signal is again performed.
On the other hand, in the case where it is determined that there is reception, the bandwidth usage efficiency in the case of passing through each of the relay stations 3 is calculated, and the relay station 3 included in the path which becomes the best bandwidth usage efficiency is identified in the next step. Thereafter, communication with the wireless terminal 4 is made by the path through the relay station until changed by selection.
In addition, as the calculation method of the band use efficiency, each method described in Example 1 can also be used here.
Although the above is a description of the path selection after entry, it can also be implemented at the entry stage.
In other words, in the state before the entry such as after the power ON, the wireless terminal 4 first receives the preamble signal from the wireless base station 2 and performs frame synchronization. At this time, the preamble signal having the highest reception level can be selected as the radio base station 2 as the entry target.
Then, the UL / DL MAP information from the selected radio base station 2 is received on the basis of the preamble signal, and the transmission timing and channel of the ranging signal are obtained. In this step, since the radio base station 2 does not know the existence of the radio terminal 4, the timing of transmission of the ranging signal is set for all radio terminals 4, or a predetermined time is set. The timings allowed for the wireless terminals 4 belonging to the group can be set and used. Of course, by preparing a plurality of channels and selecting any one of the plurality in the wireless terminal 4, distribution can be achieved, thereby reducing the collision of data transmission between the wireless terminals.
By the way, when the Ranging signal is transmitted, it is received by the surrounding radio base station 2 or the relay station 3. At this time, the wireless terminal 4 can be identified using the identification information of the wireless terminal 4 included in the Ranging signal.
The radio base station 2 and the relay station 3, which have received the Ranging signal, respectively measure the reception quality by the reception quality measuring units 28 and 41, generate the above-described adjustment information, and generate the relay station 3 Is reported to the radio base station 2, and the radio base station 2 is maintained.
Then, the communication path determining unit 17 determines the best path in the same manner as before, registers the determination result in the communication path management unit 18 and, if the relay station 3 is included in the best path, the relay station 3. The wireless terminal 4 notifies the wireless terminal 4 of the adjustment information obtained from the control unit and the adjustment information held by the wireless base station 2 if not included.
Therefore, communication for SBC, PKM, REG, DSx, etc., performed after Ranging can be performed using the selected path. The control method of the data transmission path is as described above.
Here, SBC is communication for notifying the capability information of the wireless terminal, PKM is communication for authentication, REG is communication for availability of IPV4, V6, etc., DSx is communication for making a transport connection. Communication to determine whether ARQ is applied.
Of course, the path selected from the notification after entry can also be used.
In addition, the path may be selected and set separately for each UL / DL. For example, the selection according to the first embodiment is adopted for the DL, and the selection according to the second embodiment is for the UL.
Of course, the selection according to the first embodiment and the selection according to the second embodiment may be applied to both UL and DL.
2 shows a wireless base station 2.
3 shows a relay station 3.
4 shows a wireless terminal 4;
5 is a radio frame format.
6 is a path selection flow.
7 is a radio frame format.
8 is a path selection sequence after entry.
9 is a path selection flow.
1: routing device
2: wireless base station
3: relay station
4: wireless terminal
10, 30, 50: antenna
11, 31, 51: duplexer
12, 32, 52: receiver
13, 33, 53: demodulator
14, 34, 54: decoder
15, 35, 55: control data extraction unit
16: packet generation unit
17: communication path determination unit
18: communication path management unit
19, 42, 60: control data generation unit
20: NW interface unit
21: packet identification unit
22: packet buffer unit
23: MAP information generation unit
24: PDU generation unit
25, 38, 62: encoder
26, 39, 63: modulator
27, 40, 64: transmitter
28, 41, 59: reception quality measuring unit
36, 57: MAP information analysis unit
37, 61: PDU buffer unit
56: measurement instruction analysis unit
58: data processing unit
65: signal generator for measurement
Receiving the indication information of the transmission timing transmitted from the wireless base station and received by the wireless terminal, and receiving based on the transmission timing indicated by the indication information, the wireless terminal having received the indication information is based on the indication information. A receiver for receiving a transmission signal to be transmitted by
A measuring unit for measuring a reception quality of the transmission signal obtained by reception by the receiving unit;
Transmitting unit for transmitting the measurement result measured by the measuring unit to the wireless base station
Relay station, characterized in that provided with.
And the transmitting unit transmits to the radio base station the deviation of the reception timing or the deviation of the reception frequency detected by the reception by the reception unit.
Receiving the indication information of the transmission timing transmitted from the wireless base station and received by the wireless terminal, and receiving based on the transmission timing indicated by the indication information, the wireless terminal having received the indication information is based on the indication information. Receive a transmission signal
The reception quality of the transmission signal obtained by reception is measured,
And transmitting the measurement result obtained by the measurement to the radio base station.
And the relay station transmits to the radio base station a deviation in the reception timing or a deviation in the reception frequency detected by the reception.
In a wireless base station,
A transmitter for transmitting control data for controlling the transmission timing to the wireless terminal;
A quality measuring unit for receiving a signal transmitted from the wireless terminal according to the control data without passing through a relay station, measuring the quality, and obtaining first reception quality information;
By receiving the control data transmitted from the radio base station and performing a reception operation based on the control data, the reception quality information of the signal is received from the relay station that has received the signal transmitted from the radio terminal in accordance with the control data. A receiving unit for receiving and obtaining second reception quality information;
A determination unit for selecting a communication path to the wireless terminal based on the first reception quality information and the second reception quality information
Wireless base station comprising a.
The receiving unit receives a shift in the reception timing or a shift in the reception frequency detected by the relay station by the reception of the signal, and when the relay station is included in the communication path selected by the determination unit, the shift in the reception timing or And the transmission unit transmits a deviation of a reception frequency to the wireless terminal.
In the communication path selection method in a wireless base station,
Transmit control data for controlling the transmission timing to the wireless terminal,
Receiving a signal transmitted from the wireless terminal according to the control data without passing through a relay station, measuring the quality to obtain first reception quality information,
By receiving the control data transmitted from the radio base station and performing a reception operation based on the control data, the reception quality information of the signal is received from the relay station that has received the signal transmitted from the radio terminal in accordance with the control data. Receive, to obtain second reception quality information,
And a communication path for the wireless terminal is selected based on the first reception quality information and the second reception quality information.
When the relay station receives a shift in a reception timing or a shift in a reception frequency detected by the reception of the signal, and the relay station is included in a selected communication path, the radio terminal detects a shift in the reception timing or a shift in a reception frequency. And a communication path selection method in a wireless base station.
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2007-07-13 EP EP07112494.5A patent/EP1890405B1/en not_active Expired - Fee Related
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