JP5230360B2 - Wireless communication system and wireless communication apparatus - Google Patents

Wireless communication system and wireless communication apparatus Download PDF

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JP5230360B2
JP5230360B2 JP2008282269A JP2008282269A JP5230360B2 JP 5230360 B2 JP5230360 B2 JP 5230360B2 JP 2008282269 A JP2008282269 A JP 2008282269A JP 2008282269 A JP2008282269 A JP 2008282269A JP 5230360 B2 JP5230360 B2 JP 5230360B2
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wireless communication
pilot signal
signal
base station
terminal
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JP2010109915A (en
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嘉孝 原
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三菱電機株式会社
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/24Radio transmission systems, i.e. using radiation field for communication between two or more posts
    • H04B7/26Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
    • H04B7/2603Arrangements for wireless physical layer control
    • H04B7/2606Arrangements for base station coverage control, e.g. by using relays in tunnels

Description

  The present invention relates to a wireless communication system and a wireless communication apparatus that perform wireless relay transmission.

  In recent high-speed wireless communication systems, large transmission power is required as the transmission speed increases. However, in reality, there is a limit to the transmission power of the transmitter, and there is a need for a technique that can secure a cover area under the limited transmission power. In recent years, relay transmission has attracted attention as a solution to such demands.

  In relay transmission, a relay device amplifies a signal from a transmitter and transmits the amplified signal to a receiver. When relay transmission is performed, the transmission power at the transmitter can be reduced as compared with the case where the transmitter directly transmits a signal to the receiver. Therefore, it is expected as a technique that can solve the coverage problem in an environment where the transmission power of the transmitter is limited.

  As one of such relay transmission technologies, a system configuration using a plurality of relay stations has been studied. For example, Patent Document 1 below discloses a method in which a plurality of relay stations are arranged between a transmitter and a receiver, and an optimum route is selected from a plurality of routes via the relay station.

JP 2008-085990 A

  However, according to the conventional relay transmission technique using a plurality of relay stations, it is necessary to measure the propagation state of the path in advance in order to determine the optimum path between the data transmitting station and the receiving station. Therefore, although it is important to perform channel measurement efficiently and with high accuracy, there has been a problem that the technology for realizing the channel measurement is not sufficiently disclosed in the prior art.

  Further, even when a plurality of relay stations individually support a plurality of receiving stations, it is necessary for each receiving station to estimate the propagation state from the relay station with high accuracy.

  The present invention has been made in view of the above, and an object of the present invention is to provide a radio communication system and a radio communication apparatus capable of performing channel measurement efficiently and with high accuracy when there are a plurality of relay stations. And

  In order to solve the above-described problems and achieve the object, the present invention provides a wireless communication system including a base station, a terminal, and a plurality of wireless communication devices that relay communication between the base station and the terminal. The base station transmits a control signal including a pilot signal pattern that is a frequency time arrangement of pilot signals different for each radio communication device to the radio communication device, and the radio communication device is included in the control signal. The pilot signal is extracted from the received signal based on the pilot signal pattern corresponding to the device itself, the extracted pilot signal is amplified, and the amplified pilot signal is transmitted.

  According to the present invention, since a plurality of relay apparatuses amplify and transmit pilot signals at different time frequency positions based on control signals from the base station, channel measurement can be performed efficiently and with high accuracy. , Has the effect.

  Embodiments of a wireless communication system and a wireless communication apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration example of a first embodiment of a wireless communication system according to the present invention. As shown in FIG. 1, the communication system according to the present embodiment includes a base station 1, relay devices 2-1, 2-2, and a terminal 3, and the relay devices 2-1, 2-2 are The wireless communication between the base station 1 and the terminal 3 is relayed. The terminal 3 and the relay devices 2-1 and 2-2 may be mobile terminals, terminals connected to a constant power source, or personal computers as long as they are wireless devices. Further, the control signal 4 in FIG. 1 is a control signal including an indication of the position of an amplified pilot signal described later transmitted from the base station 1.

  In the radio communication system according to the present embodiment, multi-carrier transmission or OFDMA (Orthogonal Frequency Division Multiple Access) is adopted, and a signal transmission control method for realizing efficient channel measurement for relay transmission is implemented. . In the following description, assuming that this signal transmission control method is applied to the uplink, the information signal transmission side is the terminal 3, the reception side is the base station 1, and the relay devices 2-1 and 2-2 perform the communication. Assume a relay. Note that this embodiment is an example, and the signal transmission control method described below is applicable to the downlink as well, and is also applicable to the distributed radio communication system.

  FIG. 2 is a flowchart illustrating an example of a basic procedure of signal transmission control according to the present embodiment. FIG. 3 is a diagram illustrating an example of a pilot signal that is amplified and transmitted by the relay apparatuses 2-1 and 2-2 according to the present embodiment. 3 shows an example of signals used for transmission from the terminal 3 to the relay devices 2-1 and 2-2, and the portion indicated by black hatching indicates the position of the pilot signal A. 3 shows an example of a signal used for transmission from the relay devices 2-1 and 2-2 to the base station 1, and the hatched portion indicates the relay device 2-1. The pilot signal B to be amplified is shown, and the portion indicated by black hatching indicates the position of the pilot signal C to be amplified by the relay device 2-2.

  FIG. 4 is a diagram illustrating a functional configuration example of the relay devices 2-1 and 2-2 according to the present embodiment. As shown in FIG. 4, the relay devices 2-1 and 2-2 of the present embodiment include an antenna 11, an LNA (Low Noise Amplifier) 12, a first DC (Down Converter) 13, and an A / D. (Analog to Digital converter) 14, second DC 15, signal receiver 16, local oscillator 17, frequency estimator 18, signal converter 19, signal transmitter 20, and second UC ( Up Converter) 21, D / A (Digital to Analog Converter) 22, first UC 23, and HPA (High Power Amplifier) 24. An analog area 31 indicates an area where the received signal is processed as an analog signal, and a digital area 32 indicates an area where the received signal is processed as a digital signal.

  A signal transmission control method according to the present embodiment will be described with reference to FIGS. As shown in FIG. 1, in the present embodiment, an environment in which a plurality of relay devices 2-1 and 2-2 exist is assumed. In this case, when a signal transmitted from the terminal 3 is transmitted to the base station 1, there are two routes, a route via the relay device 2-1 and a route via the relay device 2-2. The base station 1 controls the terminal 3 to perform data transmission by selecting a path suitable for data transmission from the two paths.

  FIG. 2 shows a procedure for performing this route selection and data transmission as signal transmission control. First, the terminal 3 transmits a pilot signal at a predetermined time frequency position in the multicarrier signal (step S11). For example, terminal 3 transmits a pilot signal inserted at the position of pilot signal A shown in FIG. Next, relay devices 2-1 and 2-2 (relay stations R1 and R2) relay and transmit a pilot signal included in the received signal (step S12). At this time, the relay devices 2-1 and 2-2 amplify and transmit pilot signals at different time frequency positions. It is assumed that the positions of pilot signals amplified by the relay devices 2-1 and 2-2 are notified in advance as the control signal 4 from the base station 1 to the relay devices 2-1 and 2-2. Relay devices 2-1 and 2-2 amplify and transmit the pilot signal indicated by control signal 4.

  Here, the amplification processing of the relay devices 2-1 and 2-2 will be described. In the relay devices 2-1 and 2-2, the signal received by the antenna 11 is amplified by the signal received by the LNA 12, and the first DC 13 is amplified based on a predetermined intermediate frequency clock generated by the local oscillator 17. Downconvert the signal to an intermediate frequency signal. The A / D 14 converts the intermediate frequency signal into a digital signal, the second DC 15 down-converts the digital signal into a baseband signal, and the signal receiving unit 16 performs a predetermined reception process on the baseband signal. Moreover, the frequency estimation part 18 estimates a baseband frequency. Then, the signal conversion unit 19 converts the signal after reception processing into a frequency domain signal by FFT (Fast Fourier Transform), and further extracts only the pilot signal to be amplified instructed by the control signal 4 to perform IFFT (Inverse Convert to time waveform by Fast Fourier Transform.

  The signal transmission unit 20 transmits the pilot signal converted into the time waveform by the signal conversion unit 19 as a baseband signal, the second UC 21 converts the baseband pilot signal into an intermediate frequency, and the D / A 22 The pilot signal converted into the intermediate frequency is converted into an analog signal, the first UC 23 converts the pilot signal converted into the analog signal into a radio frequency, and the HPA 24 amplifies the pilot signal converted into the radio frequency. And transmit from the antenna 11. By such processing, the relay apparatuses 2-1 and 2-2 can extract only the pilot signal indicated on the time frequency and transmit it after amplification. The above operation has been described for the case where the signal is transmitted after being converted to the intermediate frequency. However, the present invention is not limited to this, and the relay device configured to perform the predetermined reception process and the transmission process is performed at a predetermined position indicated on the time frequency. Any configuration may be used as long as the pilot signal is extracted and amplified, and the amplified pilot signal is transmitted.

  When the base station 1 receives the pilot signal that is amplified and transmitted by the relay devices 2-1 and 2-2, the base station 1 measures the channel state of the route through the relay devices 2-1 and 2-2 (step S 13). Specifically, the channel state of the route via the relay device 2-1 is measured using the pilot signal received from the relay device 2-1. There are many methods for measuring the channel state using pilot signals dispersed on the time frequency, and channel measurement can be realized by any method. Similarly, the base station 1 can measure the channel state of the route via the relay device 2-2 using the pilot signal received from the relay device 2-2. Since relay devices 2-1 and 2-2 amplify and transmit pilot signals, base station 1 has terminal 3 to relay devices 2-1 and 2-2 and relay devices 2-1 and 2-2 to base station 1. A channel state in which the routes of the two sections are combined is measured.

  The base station 1 selects a relay transmission path (path with a good channel state) suitable for data transmission of the terminal 3 according to the measured channel state (step S14). The selected relay transmission path is notified from the base station 1 to the terminal 3 and the relay devices 2-1 and 2-2 by the control signal 4, and the base station 1 sends the control signal 4 to the terminal 3 and the relay devices 2-1 and 2-2. Data transmission is performed according to the relay transmission path specified by (step S15). By such control, a route most suitable for data transmission can be selected from routes via the plurality of relay devices 2-1 and 2-2.

  The present embodiment is characterized in that relay devices 2-1 and 2-2 amplify and transmit pilot signals located at different time frequencies in the received signal. That is, even when the terminal 3 transmits a pilot signal having a certain arrangement, the base station 1 independently and accurately estimates the propagation state of the two paths by amplifying the pilot signal from which the relay station differs. it can. It can also be said that the relay devices 2-1 and 2-2 selectively amplify and transmit pilot signals.

  If the relay devices 2-1 and 2-2 amplify the pilot signals arranged at the same time frequency, the pilot signals from the relay devices 2-1 and 2-2 interfere with each other, and the channel of the relay path It becomes difficult to measure the state individually. On the other hand, if the method of this embodiment is used, the individual channel states of the two relay paths can be measured smoothly.

  In the present embodiment, the base station 1 notifies the relay station in advance of the position of the pilot signal to be amplified by the relay devices 2-1 and 2-2 using the control signal 4. At this time, it is possible to smoothly notify the pattern (position) of the pilot signal to be amplified by giving different ID numbers to the different time-frequency arrangement patterns of the pilot signals for notification.

  Moreover, it is preferable that the pilot signals amplified by the relay apparatuses 2-1 and 2-2 are arranged as evenly as possible on the time frequency so that the base station 1 can measure an average channel state in the time frequency domain. . For example, as shown in FIG. 3, a configuration is adopted in which the relay device 2-2 amplifies a pilot signal located in the middle of two pilot signals amplified by the relay device 2-1 in terms of time or frequency. Is desirable. Thus, by arranging the pilot signals amplified by each relay station alternately on the time frequency, it is possible to arrange the pilot signals evenly.

  Although the case where the number N of relay devices is 2 has been described in this embodiment, the principle of this embodiment can be applied even when N> = 3. In this case, it is possible to cope with various N by setting N kinds of patterns for the position of the pilot signal to be amplified according to the number N of relay devices.

  Further, as an example, a pilot signal pattern to be amplified corresponding to N can be defined in advance as a wireless standard. For example, when N = 2, a pilot signal arrangement obtained by dividing the arrangement of pilot signal A in FIG. 3 into two is defined in advance, and a control signal is transmitted to two relay apparatuses so as to amplify one of the pilot signal arrangements. In the case of N = 3, a pilot signal arrangement obtained by dividing the arrangement of the pilot signal A in FIG. 3 into three is defined in advance, and one of the three types of pilot signal arrangements is amplified in three relay devices. Send a control signal. In this way, the pilot signal arrangement to be amplified according to N is specified in advance, and the arrangement number is notified from the base station to the relay device as a control signal, so that information on the pilot signal to be amplified with a small number of control signals can be obtained. Can notify the relay device.

  Note that the pilot signal described in this embodiment indicates a known signal that can be grasped in advance by a terminal, a relay device, or a base station, and may be referred to as a reference signal or a sounding signal.

  As described above, in the present embodiment, the plurality of relay apparatuses 2-1 and 2-2 amplify and transmit pilot signals at different time frequency positions based on the control signal 4 from the base station 1. Therefore, the base station 1 can perform channel measurement efficiently and with high accuracy, and can smoothly select a relay route.

Embodiment 2. FIG.
FIG. 5 is a diagram illustrating a configuration example of the second embodiment of the wireless communication system according to the present invention. In the first embodiment, the case where a plurality of relay paths are selected for one terminal 3 has been described. However, in the present embodiment, unlike the wireless communication system according to the first embodiment, the terminals 3-1 and 3-2 are different from each other. An example in which communication is performed with the base station 1 via the relay devices 2-1 and 2-2 will be described.

  As shown in FIG. 5, in the present embodiment, the signal transmitted from the base station 1 is transmitted to the terminal 3-1 via the relay device 2-1, and the terminal 3-2 via the relay device 2-2. Sent to. Similarly to the first embodiment, the terminals 3-1 and 3-2 may be mobile terminals, terminals connected to a constant power source, or personal computers as long as they are wireless devices. Also, relay devices 2-1 and 2-2 of the present embodiment are the same as relay devices 2-1 and 2-2 of the first embodiment, and a pilot signal based on control signal 4 from base station 1 Is selectively amplified and transmitted. Elements having the same functions as those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted.

  The terminals 3-1 and 3-2 may receive signals simultaneously, or only one of them may receive signals. In the present embodiment, it is assumed that relay apparatuses 2-1 and 2-2 that relay terminals 3-1 and 3-2 for communication with base station 1 are defined. Then, the terminals 3-1 and 3-2 measure the channel state of the relay path used by themselves, notify the base station 1 of the state, and the base station 1 performs signal transmission according to the channel state. Are selected from terminals 3-1 and 3-2. Also, the modulation scheme, coding rate, and radio resource used by the base station 1 for communication can be appropriately selected according to the channel state of each relay path of the terminals 3-1 and 3-2.

  In order to realize such an operation, the terminals 3-1 and 3-2 need to accurately measure the channel state of the route (relay route) from the base station 1 through the relay devices 2-1 and 2-2. is there. In order to perform this accurate channel state measurement, in this embodiment, as in the first embodiment, the base station 1 amplifies and transmits to the relay apparatuses 2-1 and 2-2 via the control signal 4 The position of the pilot signal is notified. Then, when relay devices 2-1 and 2-2 receive a pilot signal transmitted from base station 1, as in the first embodiment, pilot signals at designated time frequency positions are received based on control signal 4. Amplify and transmit. Through the above operation, the terminals 3-1 and 3-2 can perform channel measurement without receiving interference from other neighboring relay apparatuses 3-1 and 3-2. The configuration and operation of the present embodiment other than those described above are the same as those of the first embodiment.

  Here, the downlink transmission from the base station 1 to the terminals 3-1 and 3-2 has been described, but the uplink transmission for signal transmission from the terminals 3-1 and 3-2 to the base station 1 is also performed. Similarly, the operation of this embodiment can be applied. In the case of uplink, the base station 1 measures the channel state of each path based on the pilot signals transmitted from the relay devices 2-1 and 2-2.

  Thus, in the present embodiment, when a plurality of relay apparatuses 2-1 and 2-2 relay signals of different terminals 3-1 and 3-2, respectively, as in the first embodiment, the base station The pilot signals at different time frequency positions are amplified and transmitted for each relay apparatus designated by 1. For this reason, the terminals 3-1 and 3-2 and the base station 1 can perform channel measurement efficiently and with high accuracy.

Embodiment 3 FIG.
In Embodiments 1 and 2, a multicarrier signal is assumed. However, the present invention is not limited to this and can be applied to any system based on multicarrier transmission. For example, as shown in “3GPP TS 36.211 V8.2.0,“ E-UTRA; Physical channels and modulation (Release 8) ”, March 2008., 3GPP-LTE (Long Term Evolution) has a single carrier (SC). ) -FDMA is employed in the uplink. This SC-FDMA is a method of performing DFT (Discrete Fourier Transform) processing on a multicarrier signal, and the principle of multicarrier transmission can be applied. Therefore, the configuration shown in Embodiments 1 and 2 can be applied to SC-FDMA in which DFT transmission processing is added to OFDMA.

  As described above, the wireless communication system and the wireless communication device according to the present invention are useful for a communication system that performs wireless relay transmission, and are particularly suitable for a communication system including a plurality of relay devices.

It is a figure which shows the structural example of Embodiment 1 of the radio | wireless communications system concerning this invention. 3 is a flowchart illustrating an example of a basic procedure of signal transmission control according to the first embodiment. It is a figure which shows an example of the pilot signal which the relay apparatus of Embodiment 1 carries out amplification transmission. FIG. 3 is a diagram illustrating a functional configuration example of the relay device according to the first embodiment. It is a figure which shows the structural example of Embodiment 2 of the radio | wireless communications system concerning this invention.

Explanation of symbols

1 Base station 2-1, 2-2 Relay device 3, 3-1, 3-2 Terminal 4 Control signal 11 Antenna 12 LNA
13 First DC
14 A / D
15 Second DC
16 signal receiver 17 local oscillator 18 frequency estimator 19 signal converter 20 signal transmitter 21 second UC
22 D / A
23 First UC
24 HPA
A, B, C Pilot signal

Claims (11)

  1. A wireless communication system including a base station, a terminal, and a plurality of wireless communication devices that relay communication between the base station and the terminal,
    The base station transmits a control signal including a pilot signal pattern, which is a frequency time arrangement of pilot signals different for each wireless communication device, to the wireless communication device,
    The wireless communication device extracts a pilot signal from a received signal based on a pilot signal pattern corresponding to the own device included in the control signal, amplifies the extracted pilot signal, and transmits the amplified pilot signal. A wireless communication system.
  2.   The radio communication system according to claim 1, wherein the pilot signal patterns are arranged so that frequency positions and temporal positions of pilot signals extracted by the same radio communication apparatus are not continuous.
  3.   The radio communication system according to claim 1, wherein the pilot signal pattern is changed according to the number of radio communication apparatuses.
  4.   The base station uses a pilot signal received from the wireless communication device to determine a channel state of a communication path for each wireless communication device, and selects a wireless communication device that relays communication with the terminal based on the channel state The wireless communication system according to claim 1, 2, or 3.
  5. A wireless communication device that relays communication with the base station is determined for each terminal,
    The said base station selects the terminal of communication object based on the channel state calculated | required using the pilot signal which the said terminal received from the said radio | wireless communication apparatus, The terminal of Claim 1, 2 or 3 characterized by the above-mentioned. Wireless communication system.
  6. A wireless communication device that relays communication with the base station is determined for each terminal,
    The base station obtains a channel state of a communication path for each wireless communication device using a pilot signal received from the wireless communication device, and selects a communication target terminal based on the channel state. Item 4. The wireless communication system according to Item 1, 2 or 3.
  7.   The method according to claim 5 or 6, wherein one or more of a modulation scheme, a coding rate, and a radio resource used for communication with a terminal corresponding to the channel state is determined based on the channel state. Wireless communication system.
  8.   The radio communication system according to claim 1, wherein a pilot signal is transmitted using a multicarrier signal.
  9.   The radio communication system according to any one of claims 1 to 7, wherein a pilot signal is transmitted based on an SC-FDMA scheme.
  10. A wireless communication device that relays communication between a base station and a terminal,
    A signal receiving means for extracting a pilot signal of a predetermined frequency time arrangement from the received signal;
    A signal transmitting means for amplifying the pilot signal extracted by the signal receiving means and transmitting the amplified pilot signal;
    A wireless communication apparatus comprising:
  11.   The radio communication apparatus according to claim 10, wherein the frequency time arrangement is determined based on a control signal including a pilot signal pattern transmitted from the base station.
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JP2011244061A (en) * 2010-05-14 2011-12-01 Sharp Corp Radio communication system, transmission device, communication method and transmission method
WO2013027014A1 (en) * 2011-08-19 2013-02-28 Sca Ipla Holdings Inc. Relay device and method
GB2501932B (en) 2012-05-11 2014-09-17 Toshiba Res Europ Ltd A wireless communications apparatus, a method and a communication system for performing relay selection
EP2706815A1 (en) * 2012-09-07 2014-03-12 NEC Corporation, Incorporated in Japan Method and system for relaying in a telecommunication network

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JP4394474B2 (en) * 2004-02-16 2010-01-06 株式会社エヌ・ティ・ティ・ドコモ Wireless relay system, wireless relay device, and wireless relay method
USRE44200E1 (en) * 2005-03-14 2013-05-07 Panasonic Corporation Wireless communication system
US7706283B2 (en) * 2006-09-25 2010-04-27 Mitsubishi Electric Research Laboratories, Inc. Decentralized and dynamic route selection in cooperative relay networks
US20100285808A1 (en) * 2006-10-27 2010-11-11 Panasonic Corporation Wireless communication apparatus and wireless communication system
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