JP2009231885A - System and method for synchronization between phs base stations - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a PHS base station to perform normal synchronization independently without decreasing the number of possible telephone calls. <P>SOLUTION: Through a system for synchronization between base stations, a PHS base station 10 adds its synchronization information to a frame signal by time-division multiple access and transmits the resulting signal to a PHS base station 20, and each of base stations following the PHS base station 20 receives a frame signal from a base station before itself, stores synchronization information that the frame signal has, synchronizes its own frame timing with the synchronization information, and further transmits the frame signal to a next base station. The synchronization information periodically changes in a fixed pattern each time transmission is performed, and stored in a slot 0 of a frame 1, 2, or 3, associated with control information of each base station, of the frame signal each time transmission is performed, and each base station having received the frame signal identifies the synchronization information that the frame signal has based upon previously held information, and synchronizes its own frame timing with the synchronization information when the synchronization information is transmitted from the base station right before this station. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a system for connecting PHS base stations via an Ethernet (registered trademark) LAN, and enables a PHS base station synchronization system to efficiently and independently maintain a stable synchronization state only with the base station. Regarding the method.

  In an Ethernet (registered trademark) LAN connection type PHS base station, since Ethernet (registered trademark) is an asynchronous line, a TDMA (Time Division Multiple Access) frame is synchronized between base stations. It is necessary to take measures.

  Therefore, in Patent Document 1, the TDMA frame timing is corrected by receiving a control channel transmitted by another PHS base station.

  Japanese Patent Application Laid-Open No. 2004-228561 employs a method of receiving synchronization information using a call slot.

In Patent Literature 3 and Patent Literature 4, a base station uses its own control slot to transmit synchronization information to another base station.
JP 2003-319451 A JP 2007-006196 A JP 2001-333038 A Japanese Patent Laid-Open No. 08-139716

  However, in the LAN connection type PHS system according to Patent Document 1, when a control channel is used, only limited synchronization information can be transmitted, and synchronization with a synchronization source CS (Cell Station: base station) is not achieved correctly. There is a problem that it cannot be detected.

  Further, in the LAN connection type PHS system according to Patent Document 1, when the synchronization channel is used, the number of call channels is reduced, and there is a problem that the number of available calls in the system is reduced.

  Furthermore, since the control channel of the PHS base station is intermittent transmission, in the technique according to Patent Document 1, when selecting a base station that is synchronized with the PHS base station, synchronization is performed if a base station that is synchronized with itself is selected. Since it is not stable, there is a problem that it is necessary to select a base station that is not synchronized with itself.

  In addition, in the method using the control channel, the amount of information that can be notified to other base stations on the radio is very small, so in order to select reliably, it is necessary to exchange control information separately on the LAN. For this purpose, there is also a problem that it is necessary to construct a mechanism for managing the correspondence between CSID (Cell Station Identifier) and IP (Internet Protocol) addresses.

  Patent Document 2 employs a method of receiving synchronization information using a call slot in order to solve the above-mentioned problems in Patent Document 1, but in this method, one call slot is always controlled synchronously. We are using for. In other words, since the data portion of one frame is used as the synchronization information, there is a demerit that the number of simultaneous calls is reduced.

  In Patent Literature 3 and Patent Literature 4, synchronization information is simply transmitted to another base station.

  The present invention has been made in view of the above, and to obtain a PHS base station synchronization system and method that enable normal synchronization independently at a PHS base station without reducing the number of calls that can be made in the system. Objective.

  In order to solve the above-described problem, the inter-base station synchronization system according to the present invention is configured such that, among a plurality of base stations connected via a network, the first base station transmits a frame signal based on time division multiple access to The synchronization information is added and transmitted to the second base station, and each base station after the second base station receives the frame signal from the base station before itself and the frame signal has the synchronization Storing information, synchronizing the frame timing of the own station with the synchronization information, and further transmitting the frame signal to the next base station, wherein the synchronization information has a constant pattern for each transmission. Each base station that has received the frame signal is stored in advance in the frame signal and stored in the first slot of the frame related to the control information of each base station. On the basis of Serial identifying the synchronization information frame signal has, in the case of a said synchronization information transmitted by the base station in front of the own station, and wherein the synchronizing frame timing of its own station in the synchronization information.

  In order to solve the above-described problem, the inter-base station synchronization method according to the present invention includes: a first base station out of a plurality of base stations connected via a network receives a frame signal based on time division multiple access; The synchronization information is added and transmitted to the second base station, and each base station after the second base station receives the frame signal from the base station before itself and the frame signal has the synchronization A base station synchronization method for storing information, synchronizing the frame timing of the own station with the synchronization information, and further transmitting the frame signal to the next base station. A procedure for periodically changing the synchronization information, a procedure for storing the synchronization information in the first slot of the frame related to the control information of each base station in each frame signal, and each base station that has received the frame signal Pre-store A step of identifying the synchronization information of the frame signal based on the information being transmitted, and if the synchronization information is transmitted by a base station in front of the own station, the frame timing of the own station is determined by the synchronization information. And a synchronization procedure.

  By periodically changing the synchronization information in a constant pattern for each transmission, it is possible to transmit a large amount of synchronization information even if the bit length of the synchronization information is short, and the synchronization information is included in each frame signal. A PHS base station that enables normal synchronization autonomously in the PHS base station without reducing the number of calls that can be made in the system by storing in the first slot of the frame related to the control information of the base station for each transmission. An inter-synchronization system and method can be obtained.

  Next, the configuration of the embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a LAN connection type PHS system. In FIG. 1, the LAN connection type PHS system according to the present embodiment includes PHS base stations 10, 20, 30 and PHS slave units 11, 21. , 31, Ethernet (registered trademark) LAN 40, and PBX 50.

  The PHS base stations 10, 20, and 30 are connected to the Ethernet (registered trademark) LAN 40 and perform synchronous communication using the synchronization information via the Ethernet (registered trademark) LAN 40.

  The PHS slave unit 11 communicates with the PHS base station 10, the PHS slave unit 21 communicates with the PHS base station 20, and the PHS slave unit 31 communicates with the PHS base station 30.

  The PBX 50 performs line switching with the public digital communication network 60 and is connected to the Ethernet (registered trademark) LAN 40.

  The PHS base station 20 synchronizes the TDMA frame timing of the PHS base station 20 with the PHS base station 10 by receiving the control channel or the synchronization channel of the PHS base station 10.

  In FIG. 1, the PHS base station 10 transmits 1-bit synchronization information (hereinafter referred to as a synchronization bit) indicating that the own station is in synchronization in the broadcast information of the control channel to other PHS base stations. At this time, the synchronization bit periodically changes in a constant pattern for each different transmission.

  The PHS base station 20 receives the synchronization bit transmitted from the PHS base station 10 and corrects the TDMA frame timing, and transmits the content of the received synchronization bit to the PHS base station 30 as it is. The contents received at the same time are stored, and it is monitored whether or not they match a known pattern.

  Here, FIG. 2 is a diagram of a frame format showing reception and transmission of synchronization information.

  In FIG. 2, the PHS base station 10 adds synchronization information to the intermittently transmitted control information, and the PHS base station 20 receives the control information to which the synchronization information of the PHS base station 10 is added in the control slot. Thus, the received synchronization information is added to the control information transmitted next. The PHS base station 30 receives the control information to which the synchronization information of the PHS base station 20 is added, and then adds it to the control information and transmits it. Thereafter, the synchronized PHS base station repeats this.

  The TDMA frame configuration of the PHS system in FIG. 2 and a method of correcting the TDMA frame timing from the received frame are well known to those skilled in the art and are not directly related to the present invention, and thus the detailed configuration is omitted. However, a frame format when the synchronization bit string is 6 bits long will be described with reference to FIG.

  As shown in FIG. 3, when the synchronization bit string is, for example, 11010, 6 bits long, the control information transmitted from the synchronization source base station includes synchronization bit 1 and synchronization bit 1 in order from the left in the head of each frame. , Synchronization bit 1, synchronization bit 0, synchronization bit 1, and synchronization bit 0 are added.

  Next, the operation in which the PHS base station receives and transmits the synchronization information of FIG. 2 will be described using the flowchart shown in FIG.

  In FIG. 4, immediately after starting up the CS which is the PHS base station (step S101), first, the control channel is searched, and a list of CSIDs of neighboring CSs and their reception levels is created (step S102).

  In step S103, the contents of the list are checked, and if the list is not empty (NO), the procedure proceeds to step S104. On the other hand, if the list is empty (YES), the CS runs on its own using the internal clock, and all the synchronization bits are transmitted with 0 (step S105).

  In step S104, control information is received for a certain period of time for the CS having the highest reception level in the list, and a sequence of synchronization bits included in the control information is acquired.

  In subsequent step S106, when a known pattern cannot be detected in the synchronization bit string (NO), the item of the CS is deleted from the list, the target is changed to the next CS (step S107), and the procedure is changed to step S103. return.

  In step S106, when a known pattern can be detected in the synchronization bit string (YES), the CS is targeted for synchronization, and thereafter, the own TDMA frame timing is corrected according to the transmission timing of the synchronization slot every frame, In addition, the received synchronization bit is included in its own control information and transmitted (step S108).

  Finally, the control channel with the synchronization bit added is transmitted (step S109).

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

  In FIG. 5, the CS in the synchronized state continuously receives the control information of the synchronization destination CS, records the synchronization bit value while correcting the TDMA frame timing, and creates a synchronization bit string (step S201).

  In the subsequent step S202, a pattern of known synchronization bits transmitted by the CS that is the synchronization source is searched in the synchronization bit string, and if detected (YES), the synchronization continuous NG counter is reset (step S203), The procedure is returned to step S201 or earlier.

  In step S202, if a known sync bit pattern cannot be detected in the sync bit string (NO), it is checked whether the sync continuous NG counter exceeds the threshold (step S204).

  In step S204, when the threshold value is not exceeded (NO), the synchronous continuous NG counter is incremented by 1 (step S205), and the procedure is returned to the step S201 or earlier.

  In step S204, when the threshold value is exceeded (YES), wireless synchronization is interrupted, and CS shifts to a free-running state using an internal clock. Thereafter, all transmitted synchronization bits are set to 0 (step S206).

  As described above, in the present invention, it can be ensured that the synchronization destination CS is the synchronization source CS or the CS synchronized with the synchronization source CS.

  Further, only one bit in the control information is used as the synchronization information, and there is no influence on other control information and the communication channel.

  Furthermore, since the inter-base station synchronization system and method according to the present invention are all completed between PHS base stations, there is no need to perform processing related to synchronization in the PBX or other servers.

  In addition, since all necessary determinations are completed only within individual base stations, there is no need to communicate with other PHS base stations, and no additional resources are required on the wireless / wired side.

  The present invention is not limited to the above-described embodiment, and can be applied to a normal PHS base station that is not connected to a LAN as shown in FIG.

  The present invention provides a synchronization system between PHS base stations that enables a PHS base station to be connected to each other via an Ethernet (registered trademark) LAN, and to maintain a stable synchronization state independently and efficiently only by the base station. Can be used.

It is a figure which shows the structure of a LAN connection type PHS system. It is a figure of the frame format which shows reception and transmission of synchronous information. It is a figure which shows a frame format in case a synchronous bit sequence is 6 bits long. It is a flowchart which shows the operation | movement which a PHS base station receives and transmits synchronous information. It is a flowchart which shows the operation | movement for a PHS base station to maintain a synchronous state. It is a figure which shows maintenance of the synchronous state in the normal PHS base station which is not LAN connection.

Explanation of symbols

10, 20, 30, 70 PHS base station 11, 21, 31 PHS cordless handset 40 Ethernet (registered trademark) LAN
50 PBX
60 Public digital communication network

Claims (12)

Among the plurality of base stations connected via the network, the first base station adds its own synchronization information to the frame signal based on time division multiple access and transmits the frame signal to the second base station. Each base station after the base station receives the frame signal from the base station before the own station, stores the synchronization information included in the frame signal, synchronizes the frame timing of the own station with the synchronization information, and A base station synchronization system for transmitting the frame signal to a next base station,
The synchronization information periodically changes in a constant pattern for each transmission, and is stored for each transmission in the first slot of the frame related to the control information of each base station in the frame signal,
Each base station that has received the frame signal identifies the synchronization information included in the frame signal based on information held in advance, and the synchronization information is transmitted by the base station before the own station. The inter-base station synchronization system characterized by synchronizing the frame timing of the own station with the synchronization information.   The information held in advance is based on the synchronization information received and stored in the past from the base station in front of the own station, and is the certain pattern included in the synchronization information. Item 4. The inter-base station synchronization system according to Item 1.   3. The synchronization information according to claim 1 or 2, wherein when the bit length is 2 or more, the synchronization information is divided and stored by 1 bit in each of the leading slots of the frame related to the control information of each base station. The synchronization system between base stations as described.   4. The inter-base station synchronization system according to claim 1, wherein the base station in front of the base station has a maximum reception level among the plurality of base stations. 5.   The inter-base station synchronization system according to any one of claims 1 to 4, wherein the base station is a PHS (Personal Handyphone System) base station.   The inter-base station synchronization system according to any one of claims 1 to 5, wherein the network is based on radio communication using time division multiple access. Among the plurality of base stations connected via the network, the first base station adds its own synchronization information to the frame signal based on time division multiple access and transmits the frame signal to the second base station. Each base station after the base station receives the frame signal from the base station before the own station, stores the synchronization information included in the frame signal, synchronizes the frame timing of the own station with the synchronization information, and A base station synchronization method for transmitting the frame signal to a next base station,
A procedure for periodically changing the synchronization information in a constant pattern for each transmission;
Storing the synchronization information in the first slot of the frame related to the control information of each base station in the frame signal for each transmission;
Each base station that receives the frame signal identifies the synchronization information that the frame signal has based on information held in advance,
In the case where the synchronization information is transmitted by a base station in front of the own station, a procedure for synchronizing the frame timing of the own station with the synchronization information;
A synchronization method between base stations, comprising:   The information held in advance is based on the synchronization information received and stored in the past from the base station in front of the own station, and is the certain pattern included in the synchronization information. Item 8. The inter-base station synchronization method according to Item 7.   9. The synchronization information according to claim 7 or 8, wherein when the bit length is 2 or more, the synchronization information is divided and stored by 1 bit in each of the leading slots of the frame related to the control information of each base station. The inter-base station synchronization method described.   The inter-base station synchronization method according to any one of claims 7 to 9, wherein the base station before the own station has the highest reception level among the plurality of base stations.   The inter-base station synchronization method according to any one of claims 7 to 10, wherein the base station is a PHS (Personal Handyphone System) base station.   The inter-base station synchronization method according to any one of claims 7 to 11, wherein the network is based on time-division multiple access wireless communication.

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