JP2007096567A - Radio communication system and method for synchronizing frame - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio communication system capable of establishing even frames excepting a super-frame head in a super-frame synchronism, and to provide a method for synchronizing the frames. <P>SOLUTION: The radio communication system is composed of a control station, a base station with at least one control station and a mobile station. In the radio communication system, the base station monitors communication data at all times, and inserts frame numbers to empty channels when the empty channels are detected. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wireless communication system, and more particularly to a wireless communication system and a frame synchronization method for establishing superframe synchronization.

  In a digital mobile communication system, a mobile station receives a radio carrier transmitted from a base station and operates in synchronization with the radio carrier. Radio carriers transmitted from the base station include a control carrier and a communication carrier.

  A radio carrier that can be commonly used (accessed) by users in the system for communication control such as communication link setting is called a control carrier, and is assigned to a user in the system according to the communication link setting. A wireless carrier that can be used is called a communication carrier.

  FIG. 7 shows a frame structure of the FDM / FDMA system standardized as a narrowband digital communication system (ARIB STD T-61) by the Radio Industries Association (hereinafter abbreviated as ARIB). A section on the time axis that defines the minimum communication unit on the wireless carrier is a frame, and the frame length is 40 msec. Also, a super frame is defined in units of 18 times the frame length.

  The control carrier includes functional channels such as a broadcast channel (BCCH: Broadcast Control Channel), a general call channel (PCH: Paging Channel), and a signal control channel (SCCH: Signaling Control Channel).

  The broadcast channel (BCCH) is a unidirectional channel for broadcasting control information from the control station to the mobile station via the base station, and is used for transferring information on the channel structure, information on the system, and the like.

  The general call channel (PCH) is a one-way channel that transfers the same information to a wide area (simultaneous call area) from the control station to the mobile station via the base station. It is done.

  The signal control channel (SCCH) is a bidirectional channel through which information is transferred between the control station and the mobile station, and is used when the mobile station's location zone is known on the control station side.

  Independent information is transferred for each zone using different frequency resources. The uplink channel transmitted by the mobile station is random access.

  As shown in FIG. 8, BCCH, PCH, and SCCH functional channels are arranged in the downlink control carrier transmitted from the base station. This means that a super frame structure is taken on the control carrier, and each functional channel is arranged at a predetermined position in the super frame.

  The arrangement of each functional channel is notified to each mobile station by the channel structure information in the BCCH, and the mobile station side receives the BCCH arranged from the top of the superframe (frame 0), so that the channel in the BCCH is received. The arrangement of each functional channel can be known from the structure information.

  When determining whether or not the mobile station is the head of a super frame, a synchronization word arranged in each frame is used. For the downlink control carrier transmitted from the base station, two types of synchronization words, ie, a synchronization word at the head of the superframe and a synchronization word other than the head, are defined. As a head, superframe synchronization is established with the base station.

  For example, Patent Document 1 discloses a technique for quickly establishing frame synchronization based on a synchronization word inserted at the same position on each frame as a wireless transmission signal.

JP 2002-26886 A

  In a digital mobile communication system, a mobile station recognizes each functional channel arrangement in a control carrier by receiving channel structure information in BCCH, and transmits and receives data for communication control such as communication link setting with a base station It is carried out.

  In order to receive the BCCH allocated from frame 0, it is necessary to establish superframe synchronization with the base station, but superframe synchronization is performed using the pattern of the synchronization word transmitted from the base station. In the established method, it is necessary to receive the synchronization word at the head of the superframe.

  However, since the synchronization word transmitted from the base station is not encoded, it is easily affected by degradation of the received electric field, fading, etc., so if an error occurs in the transmission path and the superframe head synchronization word cannot be detected or If a synchronization word is erroneously detected, a super frame cannot be established.

  Also, the synchronization word at the head of the superframe is transmitted every 18 frames (720 msec [= 40 msec × 18 frames]). If the synchronization word at the head of the superframe fails to be detected once, the head of the superframe is again detected. It takes 18 frames to detect the sync word.

  An object of the present invention is to provide a radio communication system and a frame synchronization method capable of establishing superframe synchronization even in a frame other than the head of the superframe.

The present invention is a wireless communication system including a control station, at least one base station, and a mobile station. The base station constantly monitors communication data, and detects a free channel to assign a frame number to the free station. The present invention is the above-described wireless communication system, wherein the mobile station has control information or a frame number inserted in received data. Are radio communication systems characterized by performing reception processing by predetermined operations. The present invention is a frame synchronization method comprising a control station, at least one base station, and a mobile station, The mobile station receives a control carrier transmitted from the base station, and receives the received data received by the receiving step. A frame synchronization method comprising: a determination step for determining the content; and a step of recognizing the frame number and performing frame synchronization when a frame number is inserted in the received data by the determination step. is there.

  According to the present invention, it is possible to obtain a radio communication system and a frame synchronization method capable of establishing super frame synchronization even in a frame other than the head of the super frame.

  FIG. 1 is a diagram showing a system configuration of a base zone of a radio communication system having a frame synchronization method according to the present invention. As shown in FIG. 1, the configuration of the radio communication system according to the present invention is composed of a base station 101 having a control function, a mobile station 102, and the like, and a base station 101 covers the operation area of the mobile station. Within the zone 101a, communication is performed between the base station 101 and the mobile station 102, or the mobile station 103 and the mobile station 104 (via the base station or directly).

  FIG. 2 is a configuration diagram of the base station 101 having the control function in FIG. 1, and includes a control station 201 and a base station 251. The control station 201 includes a line control device / storage device 202 and the like, and performs control such as instructing which channel and which frequency to use to the base station 251. The base station 251 includes a transmission device 252, an antenna duplexer 253, an antenna 254, an antenna 255, a reception amplifier 256, a reception device 257, a base station control device 258, and a monitoring device 259. The carrier is transmitted to the mobile station 102 or the like. A radio carrier from the mobile station 102 or the like is received.

  FIG. 3 is a configuration diagram of the mobile station 102 and the like in FIG. 1, which includes an antenna 301, an antenna duplexer 301, a transmission device 303, a reception device 304, a control device / storage device 305, and an accessory device 306. The wireless carrier is received from the mobile station, and the wireless carrier is transmitted to the base station 251.

  The radio carrier has a control channel and a communication channel. As shown in FIG. 8, the control channel is a broadcast channel (BCCH: Broadcast Control Channel), a general call channel (PCH: Paging Channel), a signal control channel (SCCH: Signaling). (Control Channel) each functional channel.

  The broadcast channel (BCCH) is a unidirectional channel for broadcasting control information from the control station to the mobile station via the base station, and is used for transferring information on the channel structure, information on the system, and the like.

  The general call channel (PCH) is a one-way channel that transfers the same information to a wide area (simultaneous call area) from the control station to the mobile station via the base station. It is done.

  The signal control channel (SCCH) is a bidirectional channel through which information is transferred between the control station and the mobile station, and is used when the mobile station's location zone is known on the control station side.

  Also, the paging channel (PCH) and the signal control channel (SCCH) are all used, and are free channels when there is no information to be transmitted to the mobile station.

  The minimum unit (unit) constituting information (message) transmitted from the base station on the control carrier is composed of signal configuration information (W) and information of layer 2 or higher. Details of the format in the unit are shown in FIG. The signal configuration information (W) indicates the head flag (F1) / final flag (F2) of information and the number of remaining units in the message or the number of valid bytes (W0) of the last unit, and is used for message disassembly and assembly. . In layers 2 and above, one message is formed by concatenating layers 2 and above in the unit given by the signal configuration information (W).

  An example of a unit and its format are shown in FIG. (A) is the leading unit, (b) is the midway unit, (c) is the last unit, (d) is one message, and (e) is the case with no message.

  Accordingly, the contents of the units constituting the PCH and SCCH functional channels when there is no information to be transmitted to the mobile station are empty channels without a message of (e).

  FIG. 1 shows the contents of the units constituting the PCH and SCCH functional channels when there is no information to be transmitted to the mobile station according to the embodiment of the present invention. The frame number of the unit is inserted into the channel at the layer 2 or higher.

  The frame number is inserted in a pattern of 00h to 11h (h = hex: hexadecimal) corresponding to 0d to 17d (d = dec, decimal system), and the frame number is notified from the base station to the mobile station. .

  At the time of notification, the coding related to each functional channel (BCCH, PCH, SCCH) in the control carrier is added with a 16-bit CRC code, which is an error detection code, as specified in ARIB STD T-61. A convolutional code that is a correction code is applied, and interleaving is performed to improve burst error resistance.

  In FIG. 2, the base station 251 performs determination and processing by the base station controller 258.

  FIG. 4 shows an operation flow of the base station controller 258 of the base station 251 in FIG.

  In step S401, control carrier transmission data notification to the transmission apparatus is started.

  In step S402, the control carrier transmission data is constantly monitored to determine whether there is control carrier transmission data (whether there is data from the transmission path).

  In step S403, when there is transmission data in step S402, each functional channel in the control carrier is encoded, and control information is notified to the transmission apparatus as transmission data for control carrier.

  In step S404, when there is no transmission data in step S402, the corresponding frame number is inserted into the empty channel (FIG. 6), each functional channel in the control carrier is encoded, and the frame number is transmitted as control carrier transmission data. Notify the device.

  In step S405, transmission of control carrier transmission data to the transmission apparatus is started.

  FIG. 5 shows an operation flow of the control device / storage device 305 of the mobile station 102 in FIG.

  In step S501, the mobile station control carrier reception process is started.

  In step S502, the received data is decoded, and it is determined whether the received data is a message (control information or a frame number inserted in an empty channel).

  In step S503, in the case of control information in step S502, control information reception processing is performed.

  In step S504, in the case of the frame number in step S502, the frame number is recognized and superframe synchronization processing is performed.

  In step S505, the control carrier reception process of the mobile station is started.

  As described above, in the embodiment of the present invention, the frame number is notified from the base station to the mobile station using an empty channel without a message. At the time of notification, the coding related to each functional channel (BCCH, PCH, SCCH) in the control carrier is added with a 16-bit CRC code, which is an error detection code, as specified in ARIB STD T-61. A convolutional code that is a correction code is applied, and interleaving is performed to improve burst error resistance.

  For this reason, the frame number notified in the format of FIG. 6 has improved error resistance with respect to the transmission path as compared with the conventional non-encoded synchronization word. Therefore, the mobile station can recognize the frame number more accurately than the conventional method of detecting the synchronization word and establishing the superframe synchronization. In general, PCH and SCCH that transfer information to a mobile station are not used at all, and there is an empty channel that always transmits empty information. It is possible to establish superframe synchronization at a higher speed than the conventional method of establishing the superframe synchronization by detecting the head synchronization word.

  Further, in the embodiment of the present invention, for simplification of description, the system configuration has a single base station. However, depending on the mode of the system, such as when there are a plurality of base stations or a system having relay stations, It goes without saying that it is possible to adapt to the above.

It is a figure which shows the system configuration | structure of the base zone of the radio | wireless communications system which has the frame synchronization method by this invention. It is a block diagram of the base station which has a control function in FIG. It is a block diagram of the mobile station in FIG. The operation | movement flow of the base station control apparatus of the base station in FIG. 2 is shown. The operation | movement flow of the control apparatus and memory | storage device of the mobile station in FIG. 3 is shown. An example of frame number notification according to an embodiment of the present invention will be described. The frame structure of FDM / FDMA system is shown. An arrangement example of functional channels of BCCH, PCH, and SCCH is shown. Details of the format in the unit are shown. Examples of units and their formats are shown.

Explanation of symbols

101: base station, 101a: base zone, 102, 103, 104: mobile station, 201: control station, 202: line control device / storage device, 251: base station, 252: transmission device, 253: antenna duplexer, 254,255: antenna, 256 : Receiving amplifier, 257: receiving device, 258: base station control device, 259: monitoring device, 301: antenna, 302: antenna duplexer, 303: transmitting device, 304: receiving device, 305: control device / storage device, 306 : Attached equipment.

Claims (3)

A wireless communication system comprising a control station, at least one base station, and a mobile station,
The base station constantly monitors communication data, and when a free channel is detected, inserts a frame number into the free channel. The wireless communication system according to claim 1,
The mobile communication system, wherein the mobile station performs reception processing by a predetermined operation when control information or a frame number is inserted in the received data. A frame synchronization method comprising a control station, at least one base station, and a mobile station,
The mobile station receives a control carrier transmitted from the base station; and
A determining step of determining the content of the received data received by the receiving step;
A frame synchronization method comprising: a step of recognizing the frame number and performing frame synchronization when a frame number is inserted in the received data in the determination step.

Images