JP2011182475A - Repeater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a repeater which relays communication by establishing synchronization between a base station and a radio terminal without mounting a GPS. <P>SOLUTION: A repeater includes a donor unit communicating with a base station and a remote unit communicating with a radio terminal. The donor unit receives a signal from the base station and identifies a preamble in the received signal to establish synchronization with the base station. Thus, a head of a communication frame between the base station and the repeater is determined. When synchronization between the base station and the donor unit is established, the remote unit starts a procedure for establishing synchronization with the radio terminal. The remote unit receives information relating to the timing of the frame head from the donor unit, determines the same timing as the frame head, and transmits a preamble to be referred to when the radio terminal establishes synchronization. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a repeater that relays a signal from a base station to a wireless terminal, and more particularly to a technique for establishing synchronization.

  In communication between a base station and a wireless terminal, a repeater may be installed to execute communication with a wireless terminal at a position where it is difficult to receive a wireless signal from any base station. The repeater relays a signal from the base station to the wireless terminal, and normally amplifies the signal received from the base station and outputs the amplified signal to the wireless terminal.

  In order to perform communication between the base station and the repeater and between the repeater and the wireless terminal, it is necessary to establish synchronization between the base station and the repeater and between the repeater and the wireless terminal.

  When communication is performed between the base station and the wireless terminal, communication is performed as shown in FIG. In FIG. 8, Tx means transmission and Rx means reception. Consider that a repeater is sandwiched between them and the repeater relays a signal from a base station.

  Here, when a repeater is placed between a base station and a wireless terminal and the repeater relays communication between the base station and the wireless terminal, the WiMAX communication standard suppresses interference and improves communication quality. As shown in FIG. 9, the beginning of the transmission / reception frame (time T0, T2 in FIG. 9) is from the upper side to the lower side, that is, in the path from the base station to the wireless terminal, the timing of the downlink (DL in FIG. (UL in FIG. 9) is specified to coincide with the timing. Determining that the timing of the beginning of this frame is aligned among communication devices is called establishing synchronization. Note that one UL is combined with a preamble that is a synchronization signal added before DL and DL, and the length of one frame is 5 msec.

  As a technique for establishing synchronization, it is conceivable to use the technique described in Patent Document 1. According to the technique of Patent Document 1, a GPS (Global Positioning System) is mounted on each of a base station, a repeater, and a wireless terminal, and a rising edge of a clock (1 clk / sec) that is ultra-high precision time information output from the GPS is determined. Synchronization can be established so that the beginning of each frame (200 frames) matches.

  Non-Patent Document 1 describes the establishment of synchronization in WiMAX.

JP 2000-197108 A

Impress standard textbook series WiMAX textbook, written by Takashi Shono

  By the way, there is a problem that enormous cost is required since the GPS of the above-mentioned Patent Document 1 must be installed in the base station and the repeater.

  Accordingly, an object of the present invention is to provide a repeater that can establish synchronization with a wireless terminal and a base station that does not have a GPS and yet conforms to the WiMAX communication standard.

  An aspect of the present invention is a repeater that relays communication between a base station and a radio terminal, a donor unit that performs communication with the base station, a remote unit that performs communication with a radio terminal, the donor unit, and the A donor-remote communication unit that communicates with a remote unit, and the donor unit establishes synchronization with the base station by receiving a preamble transmitted from the base station, and transmits a frame including the preamble. Is transmitted to the remote unit via the inter-donor-remote communication unit, and the remote unit transmits the preamble to the wireless terminal based on the instruction and the timing, whereby the preamble is transmitted. Information related to location registration performed by the wireless terminal synchronized with the timing at which the information is transmitted is transmitted via the inter-donor-remote communication unit. The donor portion by transmitting to the base station to perform communication, and performs location registration of the wireless terminal to the base station.

  With the configuration as described above, the repeater establishes synchronization with the base station without GPS, transmits a preamble signal without violating the WiMAX communication standard, and the preamble signal is received by the wireless terminal. Thus, synchronization with the wireless terminal can be established and communication can be executed.

1 is a system configuration diagram of a communication system. It is the functional block diagram which showed the function structure of the base station. It is the functional block diagram which showed the function structure of the repeater. It is the functional block diagram which showed the function structure of the radio | wireless terminal. It is the flowchart which showed the sequence of the synchronization establishment between the donor part of a base station and a repeater. It is the flowchart which showed the operation | movement of the repeater at the time of synchronization establishment. It is the flowchart which showed the sequence of the synchronization establishment between the remote part of a repeater, and a radio | wireless terminal. It is a figure which shows that a base station and a radio | wireless terminal communicate. It is a figure which shows communication with a base station, a repeater, and a radio | wireless terminal. It is the figure which showed the example of arrangement | positioning in the case of arrange | positioning apart the donor part and remote part of a repeater.

Hereinafter, a repeater according to an embodiment of the present invention will be described with reference to the drawings.
<Embodiment>
<Configuration>
FIG. 1 is a system configuration diagram showing a system configuration of a communication system including a repeater according to the present invention.

  As can be seen from FIG. 1, the communication system includes a base station 100, a repeater (hereinafter referred to as “repeater”) 200, and a wireless terminal 300. The communication system performs communication in accordance with a communication standard of WiMAX (IEEE802.16). In the system diagram, only one unit is shown, but actually, the communication system includes more base stations, repeaters, and wireless terminals.

  The base station transmits a signal to the repeater, and the repeater relays the signal and transmits it to the wireless terminal. The wireless terminal transmits a signal to the repeater, and the repeater relays the signal and transmits the signal to the base station. Thereby, the wireless terminal can execute communication with other wireless terminals.

  In order to execute the communication, it is essential to establish synchronization between the base station and the repeater and between the repeater and the wireless terminal. In the present embodiment, a method of establishing without using GPS in establishing the synchronization is shown. In the present embodiment, the method of establishing synchronization will be described in detail, and the description of communication will be omitted on the assumption that communication conforming to the WiMAX standard is executed.

  FIG. 2 is a functional block diagram illustrating a functional configuration of the base station 100. As shown in FIG. 2, the base station 100 is configured to include an upper communication unit 110, a control unit 120, a lower communication unit 130, and a storage unit 140.

  The upper communication unit 110 is connected to a telephone network (not shown) and has a function of executing communication with other base stations.

  The control unit 120 has a function of controlling each unit of the base station 100.

  The lower communication unit 130 includes an antenna 131 and has a function of executing communication with the wireless terminal and the repeater. The lower-level communication unit 130 is connected to the DL-MAP including information necessary for communication in the preamble and downlink directions for each frame in order to establish synchronization with the repeater and the wireless terminal via the antenna 131, and It transmits by including UL-MAP including information such as frequency necessary for communication in the link direction.

  The storage unit 140 has a function of storing programs and data necessary for the operation of the base station 100 and stores a neighbor list 141. The neighbor list 141 is information indicating information on base stations and repeaters that are referred to as handover destination candidates when a wireless terminal or repeater with which the base station 100 has established synchronization performs handover to another base station. is there.

  The above is the description of the base station 100.

  Next, the repeater 200 will be described.

  FIG. 3 is a functional block diagram showing a functional configuration of repeater 200. As shown in FIG. 3, the repeater 200 includes a donor unit 210 and a remote unit 220. The donor unit 210 has a function of executing communication with the base station 100. The remote unit 220 has a function of executing communication with the wireless terminal 300. The donor unit 210 and the remote unit 220 operate with the same clock supplied.

  The donor unit 210 includes a first communication unit 211 and an activation control unit 214.

  The first communication unit 211 includes an antenna 212 and a first synchronization establishment unit 213. The first communication unit 211 has a function of communicating with a base station via the antenna 212. The first communication unit 211 has a function of transmitting a signal received from the base station via the antenna 212 to the remote unit 220. Further, it has a function of transmitting a signal transmitted from the remote unit 220 to the base station via the antenna 212.

  The first synchronization establishing unit 213 holds a reference signal of the preamble, and in a state where synchronization with the base station is not established, a signal that matches the reference signal held among the signals received by the first communication unit Based on the MAP information (including information such as downlink frequency band, downlink burst allocation, uplink frequency band, uplink burst allocation, etc.) following the preamble, by detecting and identifying the preamble Has the function of establishing synchronization with.

  The activation control unit 214 establishes synchronization with the base station by the first synchronization establishment unit 213, converts the timing when the preamble arrives from the base station and its period into the timing and period in its own operation clock, and converts the timing and period The second synchronization establishment unit 223 is notified, and the transmission of a frame including a preamble necessary for synchronization is instructed.

  The remote unit 220 includes a second communication unit 221.

  The second communication unit 221 includes an antenna 222 and a second synchronization establishment unit 223. The second communication unit 221 has a function of executing communication with a wireless terminal connected to the remote unit via the antenna 222. The second communication unit 221 has a function of transmitting the signal transmitted from the first communication unit 211 to a wireless terminal designated via the antenna 222. In addition, it has a function of transmitting a signal received via the antenna 222 to the first communication unit 211.

  The second synchronization establishing unit 223 generates a preamble and MAP information to be included in each frame by the second communication unit 221 so that the preamble is transmitted at the same timing as the timing instructed from the activation control unit 214. The second communication unit 221 transmits a signal including the generated information at a timing notified from the activation control unit 214. When the preamble and the MAP information are received by the wireless terminal, various synchronization procedures are started, and the second synchronization establishing unit 223 negotiates with the wireless terminal as necessary to establish synchronization.

  The above is the description of the repeater 200.

  From here, the functional configuration of the wireless terminal 300 will be described. FIG. 4 is a functional block diagram illustrating a functional configuration of the wireless terminal 300.

  As illustrated in FIG. 4, the wireless terminal 300 includes a communication unit 310, a display unit 320, an audio processing unit 330, an operation unit 340, a storage unit 350, and a control unit 360.

  The communication unit 310 has a function of demodulating the reception signal received from the antenna 311 into a reception voice signal and a reception data signal, and outputting the demodulated reception voice signal and reception data signal to the control unit 360. In addition, the communication unit 310 has a function of modulating the transmission voice signal A / D converted by the voice processing unit 330 and a transmission data signal such as an electronic mail given from the control unit 360 and outputting the modulated data signal from the communication antenna 311. Have. The communication unit 310 has a function of receiving a signal from a base station or a repeater and establishing synchronization with the base station or the repeater.

  The display unit 320 includes a display realized by an LCD (Liquid Crystal Display) or the like, and has a function of displaying an image according to an instruction from the control unit 360 on the display.

  The voice processing unit 330 performs D / A conversion on the received voice signal output from the communication unit 310 and outputs the received voice signal to the speaker 332, and A / D converts the transmission voice signal acquired from the microphone 331 to be converted. It has a function of outputting a signal to the control unit 360.

  The operation unit 340 includes a numeric keypad group, an on-hook key, an off-hook key, a direction key, a determination key, a mail key, a side key, and the like, and has a function of receiving a user operation and outputting the received operation content to the control unit 360.

  The storage unit 350 includes a ROM (Read Only Memory) and a RAM (Random Access Memory), and is realized by a small hard disk, a nonvolatile memory, or the like. The storage unit 350 has a function of storing music data, image data, and the like in addition to various data and programs necessary for the operation of the wireless terminal 300. The storage unit 350 stores a neighbor list received from a base station or a repeater that has established synchronization. The neighbor list is referred to by the communication unit 310 when the wireless terminal 300 executes a handover.

  The control unit 360 is realized by a CPU (Central Processing Unit), for example, and has a function of controlling each unit of the wireless terminal 300.

The above is the description of the wireless terminal 300.
<Data>
From here, various data required for synchronization will be described.

  FIG. 5 is a conceptual diagram showing an example of a frame configuration of signals exchanged between the base station and the repeater. In WiMAX, the frame length is specified to be 5 msec.

  As shown in FIG. 5, the frame includes a downlink subframe and an uplink subframe. Between the downlink subframe and the uplink subframe, guard times for performing transmission / reception switching processes such as TTG (Transmit Transition Gap) and RTG (Receive Transition Gap) are provided. Communication between the base station and the repeater and between the repeater and the wireless terminal is executed in a format in which the frames are continuous.

  The downlink subframe includes a preamble, an FCH (Frame Control Header), a DL-MAP (Down Link-MAP), an UL-MAP (Up Link-MAP), and a downlink burst.

  The preamble is a signal for making the head of a frame recognize a head of a frame by a repeater or a wireless terminal as viewed from the base station, and a wireless terminal as viewed from the repeater.

  FCH is data indicating the data structure of the subsequent DL-MAP.

  DL-MAP is data required for a repeater or a wireless terminal to establish downlink synchronization.

  UL-MAP is data required for a repeater or a wireless terminal to establish uplink synchronization.

  The downlink burst is actual data transmitted from the base station to the repeater or the wireless terminal. The actual data here includes, for example, call voice data and MCBCS distribution data. In addition, DL-MAP and extended communication control information not included in UL-MAP may be included.

  TTG is a guard time for data communication direction, that is, switching processing from the downlink to the uplink, in the base station, repeater, and wireless terminal.

  The uplink subframe includes a ranging area, a CQICH (Channel Quality Information Channel) area, an ACK (Acknowledgement) area, and an uplink burst.

  The ranging area is an area for transmitting a band request or a signal for performing ranging. The bandwidth request is processing for requesting allocation of a data area for the wireless terminal to transmit data to the base station. Ranging is a process for ensuring time and frequency synchronization between a base station and a repeater or a wireless terminal.

  The CQICH area is an area for transmitting channel quality information on the receiving side.

  The ACK area is an area used for an ACKCH (ACK Channel) for performing ACK / NAK feedback for a hybrid automatic retransmission request.

  The uplink burst is actual data transmitted from the wireless terminal to the repeater or the base station.

  The RTG is a guard time for the data communication direction, that is, switching processing from the uplink to the downlink, in the base station, repeater, and wireless terminal.

The above is the description of the frame.
<Operation>
From here, the operation | movement for the synchronization establishment in this Embodiment is demonstrated.

  First, a series of flow for establishing synchronization will be described based on the timing chart of FIG.

  First, the base station 100 transmits a signal including a preamble signal, DL-MAP, and UL-MAP in each frame. In response to the preamble signal, the repeater donor unit 210 synchronizes with the base station.

  When synchronization between the donor unit 210 and the base station 100 is established (step S601), the donor unit 210 sets the timing for receiving the preamble from the base station 100 as the start timing of the frame including the preamble. 220 is notified (step S602).

  When notified of the timing of the frame from the donor unit 210, the remote unit 220 transmits a signal including a preamble signal, DL-MAP, and UL-MAP in each frame at the same timing as the notified timing (step). S603).

  The wireless terminal 300 receives the preamble signal transmitted from the remote unit 220 (step S604), and establishes synchronization with the remote unit 220 (step 605).

  By establishing synchronization between the base station and the repeater and establishing synchronization between the repeater and the wireless terminal, the wireless terminal can communicate with other wireless terminals via the repeater and the base station.

  Next, the operation for establishing synchronization in the repeater will be described with reference to the flowchart shown in FIG.

  The first communication unit 211 of the donor unit 210 scans each frequency and receives a signal from the base station. The first synchronization establishment unit 213 identifies the preamble of the signal received from the base station by comparing it with the held reference signal, and the frame length is a fixed length (5 msec). The start timing can be specified, the start timing of successive frames is recognized, and synchronization is established (step 701). When synchronization is established, the configuration of the downlink burst and the configuration of the uplink burst are specified from the DL-MAP and the UL-MAP, and then various procedures for network entry are executed while performing negotiation with the base station. Details of the procedures for network entry are described in Non-Patent Document 1, for example.

  The activation control unit 214 of the donor unit 210 detects the timing at which the first synchronization establishment unit 213 establishes synchronization with the base station and receives a preamble and its period in its own operation clock. Then, the detected timing and cycle are transmitted to the remote unit (step S702). Specifically, the activation control unit 214 outputs a pulse signal in which the clock is masked at a timing other than the timing at which the preamble is scheduled to be received among its own operation clocks.

  The remote unit 220 operates by receiving a clock supplied from the same clock signal generator as that of the donor unit 210, and transmits a preamble at the timing and period notified from the activation control unit 214 in the clock (step S703). ). As a result, the remote unit 220 can transmit a frame including the preamble so that the radio terminal 300 receives the preamble at the same timing as the timing at which the donor unit 210 receives the preamble from the base station 100. Specifically, the preamble is output at the timing when the pulse signal output from the activation control unit 214 and the own operation clock match.

  As a result, as shown in FIG. 9, communication can be performed by unifying the frame timing between the base station and the repeater and between the repeater and the wireless terminal. When transmitting a signal from the base station to the wireless terminal, the signal transmitted from the base station to the remote part of the repeater between the times T0 and T1 is the downlink of the subsequent frame, for example, between the times T2 and T3. Sent from the repeater to the wireless terminal. Conversely, when a signal is transmitted from the wireless terminal to the base station, the signal transmitted from the wireless terminal to the repeater during the time T1-T2 is the uplink of the subsequent frame, for example, the repeater's time at the time T3-T4. Sent from the donor unit to the base station.

  As described above, in this embodiment, GPS is not mounted for synchronization between a base station and a repeater and between a repeater and a wireless terminal so that communication according to the WiMAX communication standard can be executed. Can be realized. Since the GPS is not installed, the circuit scale can be reduced and the manufacturing cost can be reduced.

<Supplement>
In the above embodiment, the method of implementing the present invention has been described, but it is needless to say that the embodiment of the present invention is not limited to this. Hereinafter, various modified examples included in the concept of the present invention other than the above embodiment will be described.
(1) In the above-described embodiment, the repeater is shown in which the donor unit 210 and the remote unit 220 are integrated and fit in one housing. However, the donor unit 210 and the remote unit 220 of the repeater do not need to be housed in the same housing. For example, the donor unit 210 and the remote unit 220 may be installed separately as shown in FIG. FIG. 10 is a diagram showing an example when a repeater is installed indoors. According to FIG. 10, it is easy to execute communication with the base station by installing the donor unit 210 so as to be close to the outdoors, and communication with a wireless terminal indoors by installing the remote unit 220 indoors. Can be easier to execute. Further, by installing the donor unit 210 and the remote unit 220 apart from each other, it is possible to prevent the signal transmitted / received by the donor unit 210 and the signal transmitted / received by the remote unit 220 from interfering with each other as much as possible.

Communication between the donor unit 210 and the remote unit 220 is performed in accordance with, for example, the communication standard IEEE802.3. It is desirable that the communication here has no communication delay. However, when there is a communication delay between the donor unit 210 and the remote unit 220, it is necessary to execute control in consideration of the delay time. In particular, when establishing synchronization, when the donor unit 210 establishes synchronization with the base station and notifies the timing for transmitting the preamble, the remote unit 220 transmits the preamble by subtracting the delay time from the notified timing. There must be.
(2) In the above embodiment, the synchronization between the wireless terminal and the base station is described, and the case of the repeater and the wireless terminal is not described as being the same. For registration, the wireless terminal does not register the location with the repeater, but registers the location with the base station with which the repeater that the wireless terminal is trying to synchronize is communicating.
(3) In the above embodiment, one repeater is sandwiched between the base station and the wireless terminal, but a plurality of repeaters may be sandwiched.
(4) In the embodiment described above, the first synchronization establishing unit 211 or the communication unit 310 holds a reference signal for specifying a preamble in advance, detects a signal that matches the reference signal, and specifies the preamble. Showed that. However, it is also possible to specify the preamble by the following method without using the reference signal.

That is, for example, 10 symbols of data having the same content are used as a preamble, and the receiving side compares the received signal with a signal obtained by delaying the received signal by one symbol. Then, since a portion that matches nine symbols is detected, the portion including the nine symbols and the preceding symbol is specified as a preamble. The preamble can also be specified by this method.
(5) Control composed of a program code for causing a processor such as a repeater and various circuits connected to the processor to execute the operation related to synchronization shown in the above-described embodiment, the process of notifying the transmission timing of the preamble in the repeater, and the like. The program can be recorded on a recording medium, or can be distributed and distributed via various communication paths. Such recording media include IC cards, hard disks, optical disks, flexible disks, ROMs, and the like. The distributed and distributed control program is used by being stored in a memory or the like that can be read by the processor, and the processor executes the control program, thereby realizing various functions as shown in the embodiment. Will come to be.

  The repeater according to the present invention can be utilized as a repeater that establishes synchronization with a base station and a wireless terminal and relays communication without GPS.

100 base station 110 upper communication unit 120 control unit 130 lower communication unit 131 antenna 140 storage unit 141 neighbor list 200 repeater 210 donor unit 211 first communication unit 212 antenna 213 first synchronization establishment unit 214 activation control unit 220 remote unit 221 second Communication unit 222 Antenna 223 Second synchronization establishment unit 300 Wireless terminal 310 Communication unit 311 Antenna 320 Display unit 330 Audio processing unit 331 Microphone 332 Speaker 340 Operation unit 350 Storage unit 351 Neighbor list 360 Control unit

Claims (1)

A repeater that relays communication between a base station and a wireless terminal,
A donor unit that communicates with the base station;
A remote unit for communicating with the wireless terminal;
A donor remote inter-communication unit that communicates with the donor unit and the remote unit,
The donor unit establishes synchronization with the base station by receiving a preamble transmitted from the base station, and sends an instruction to transmit a frame including a preamble and the timing of the transmission to the inter-donor remote communication unit. To the remote part via
The remote unit transmits a preamble to the wireless terminal based on the instruction and the timing,
By transmitting information related to location registration performed by the wireless terminal synchronized with the timing at which the preamble is transmitted to the base station where the donor unit performs communication via the donor-remote communication unit, the wireless terminal A repeater that performs terminal location registration with the base station.

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