JP2766087B2 - TDMA frame timing information transmission method in mobile communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system, and more particularly to a frame timing information transmission system in a mobile communication system in which an access system between a radio base station and a mobile communication terminal is performed by multi-carrier TDMA (Time Division Multi Access).

[0002]

2. Description of the Related Art In recent years, for example, in offices and the like, an extension telephone housed in a private branch exchange or the like has been increasingly provided to each employee in order to improve work efficiency. In this way, when a telephone is handed to each employee, since the extension number corresponds to each individual, it is easier than a wired telephone fixed on a desk as before, even for a small movement. A cordless telephone with excellent portability is desired. For this reason, for example, a private branch exchange in which a cordless subscriber circuit for accommodating a wireless base station of a cordless telephone is provided in an exchange and exchange processing is performed in the same manner as a wired telephone is being developed. 2. Description of the Related Art Conventionally, as a mobile communication system of a private branch exchange accommodating a wireless terminal, there is a private paging for calling and transmitting a message to a person carrying a radio paging receiver. In such a mobile communication system, for example, an analog transmission system based on FM modulation is used.

[0003]

On the other hand, even in a mobile communication system in which a private branch exchange accommodates a cordless telephone, it is necessary to prevent the contents of a call between telephones from leaking outside easily. However, in the case of the analog transmission system, there is a disadvantage that a third party can easily eavesdrop radio waves between the wireless base station and the mobile communication terminal by adjusting the wavelength of the receiver. It is important that the mobile communication terminal has excellent portability, but in the case of the analog transmission system, there is a disadvantage that it is difficult to reduce the size and weight.
Furthermore, in the case of the analog transmission system, when a mobile communication terminal is used as a data terminal, the transmission capability is low, and the mobile communication terminal is not suitable for high-speed data transmission. In addition, the entire communication system, including a wired system, has been digitized in order to make effective use of channels, and the development of a mobile communication system using a digital transmission system in a private branch exchange is desired.

[0004] For this reason, it is conceivable to digitize a radio base station and a mobile communication terminal in a mobile communication system of a private branch exchange by, for example, a multicarrier TDMA system. When digital mobile communication by the multicarrier TDMA method is applied to a private branch exchange, it is desirable to synchronize a TDMA frame in a service area with a synchronization signal of the exchange. As a method of adjusting this synchronization signal,
Transmitting a TDMA frame timing signal which is centrally held by a private branch exchange from a cordless subscriber circuit accommodating a radio base station to a radio base station, and adjusting the TDMA frame phase between the radio base station and the mobile communication terminal. Can be considered.

At this time, in order to design a highly economical cordless subscriber circuit, an interface between the cordless subscriber circuit and the radio base station is provided by, for example, an architecture of a digital terminal interface accommodating a digital multifunctional telephone or a data terminal. It is effective to use This is an architecture developed for economically accommodating digital terminals in a private branch exchange. A digital terminal subscriber circuit accommodating a plurality of digital terminals is a one-chip microcomputer having a serial input / output unit (SIO). Controlled. The digital terminal subscriber circuit permits transmission of uplink control information from a plurality of digital terminals by polling. When such an architecture is adopted, the signal configuration in the layer 1 between the subscriber circuit and the terminal includes the K channel in addition to the 2B channel (64 kb / s × 2) user information and the D channel (16 kb / s) control information. (8
kb / s), and this K channel is used as a terminal polling signal. However, if the conventional technology of this digital terminal subscriber circuit is used as it is for a cordless subscriber circuit, the TDMA frame timing signal cannot be transmitted because the downlink information bits from the cordless subscriber circuit to the radio base station are empty. There was a disadvantage that synchronization could not be achieved.

The present invention solves such disadvantages of the prior art, and uses a layer 1 having 2B + D + K used for accommodating digital terminals between a wireless subscriber circuit accommodating a wireless base station and a wireless base station. Another object of the present invention is to provide a TDMA frame timing information transmission method in mobile communication capable of transmitting a TDMA frame timing signal.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a switching system, a plurality of radio base stations accommodated in the switching system, and a radio link between these radio base stations. In a system including a plurality of mobile stations communicating with each other, a TDMA method is used for access between a radio base station and a mobile station. Uplink control information from the radio base station to the switching system is permitted by polling from the switching system. This polling signal is synchronized with the TDMA frame timing,
Sent from the switching system to the radio base station.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a TDMA frame timing information transmission system in mobile communication according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 2, there is shown a block diagram showing an embodiment when the TDMA frame timing information transmission system in mobile communication according to the present invention is applied to a digital private branch exchange. This private branch exchange is a multicarrier T
This is an exchange for realizing digital mobile communication by DMA, and as shown in FIG.
1 to 11-n, a time division switch 30, and a central processing module 40. Line trunk module 11
Is a line accommodating unit in which an interface circuit such as a wired or wireless subscriber terminal or various trunks is provided as necessary. FIG. 2 shows a cordless subscriber circuit 17 directly related to the present embodiment.

The cordless subscriber circuit 17 accommodates a plurality of radio base stations 51 and communicates with the base stations 51 by 2B + D + K.
Interface circuit for exchanging signals.
Each cordless subscriber circuit 17 is connected to the time division switch 30 or the central processing module 40 via a predetermined switch or controller (not shown). Wireless base station 5
1 is a base station for exchanging voice signals and control signals by multi-carrier TDMA with a cordless telephone 61 which is a wireless subscriber terminal by a micro zone,
It is housed in the cordless subscriber circuit 17 of the exchange 1. The wireless base stations 51 are arranged at predetermined intervals so that communication can be performed even when the cordless telephone 61 moves between zones during communication. Thus, even if the cordless telephone 61 moves across the plurality of wireless base stations 51 during communication, the switching processing of the wireless base stations is executed and the telephone call can be continued.

The time division switch 30 is connected to the line trunk 1
This is a switch that forms a communication path between terminals or trunks accommodated within the line 1 or between the line trunks 11. The time division switch 30 is connected to the central processing module 40, and performs switching processing in a time division multiplex system in accordance with a connection control instruction from the module 40. The central processing module 40 is a control circuit that controls each component of the exchange 1, and executes connection control according to a call processing program. The central processing module 40 also has a TD of 8 ms period.
An MA frame clock generator and a clock generator for ping-pong transmission burst having a period of 125 μs (both not shown) are included, and these clocks are supplied to the line trunk module.

In FIG. 1, the cordless subscriber circuit 17 has four
A functional block diagram when two wireless base stations are accommodated is shown. In this embodiment, the TDMA frame period is 8 m
In this case, ping-pong transmission with a burst period of 125 μs is performed between the cordless subscriber circuit 17 and the wireless base station 51. The TDMA frame clock and the ping-pong transmission burst clock are synchronized clocks. FIG.
Shows the signal format. As shown in FIG. 3, layer 1 between the cordless subscriber circuit 17 and the radio base station 51
The signal configuration is 2B channel of user information (64 kb / s ×
2) It is composed of a D channel (16 kb / s) of control information and a K channel (8 kb / s). The K channel signal is used as a polling signal to the radio base station 51. Note that FIG. 1 shows each element directly related to the present invention, and the illustration of each element of the B-channel system not directly related is omitted.

Microcomputer (μCPU) 19
Are two external clock input terminals, one serial I /
This control circuit has an O terminal and a base station selection signal output terminal, and has a selection signal transmission function of selecting the base station 51. That is, the computer 19 is connected to the clock line 200.
, And a burst clock of 125 μs via the clock line 202 are input from the switch body, and the radio base station 51 is selected in synchronization with these clocks. Computer 19
Is connected to a first selector (SEL1) 21 via a signal line 204 connected to a serial I / O terminal, and performs input / output of a serial signal. Computer 1
9 is connected to a first selector 21 and a second selector (SEL2) 23 via a signal line 206 connected to a base station selection signal output terminal, and sends out a selection signal for base station selection.

The first selector 21 has 4
Connected to one layer 1 signal generation circuit L1. The layer 1 signal creation circuit L1 is connected to the radio base station 51, and takes a physical and electrical interface therewith. The first selector 21 decodes the base station selection signal from the microcomputer 19 and recognizes which wireless base station 51 has been selected. Then, the computer 19 is connected to the layer 1 signal generation circuit corresponding to the selected wireless base station 51. Thereby, the 16 kb / s uplink control information from the selected wireless base station 51 is input to the serial I / O of the computer 19. Further, the 16 kb / s downlink control information input from the computer 19 is sent to the selected wireless base station 51.

The second selector is connected to four layer 1 signal generation circuits L1 by K channels. The second selector decodes a base station selection signal from the computer 19 and selects a radio base station 51 for which transmission of uplink control information is permitted, using the downlink K channel. This K
The channel signal is transmitted to the radio base station 51 in synchronization with a ping-pong transmission burst clock supplied centrally by the private branch exchange. Therefore, the variation of the K channel bits reproduced by the radio base station 51 is only the transmission delay difference due to the cable connecting the cordless subscriber circuit 17 and the layer 1 signal generation circuit L1.

FIG. 4 shows the transmission timing of the downlink K channel transmitted to each radio base station 51. When transmitting a signal to the layer 1 signal generation circuit L1 on the downstream K channel as a polling signal, the computer 19 starts the TDMA frame (8 ms),
Transmission control is performed so that the start change point of the channel signal coincides. That is, the starting change point of the polling is 8 ms.
Appears every time. The radio base station 51 synchronizes with the start change point and uses it as a signal for frame alignment for performing burst transmission / reception with the mobile terminal 61 (see FIG. 2). For example, when the amount of information for performing burst transmission / reception is large, the polling time is long as shown in the TDMA frame 300 of the radio base station 51-1. Even in this case,
Next, the TD of the wireless base station 51-2 for which polling is valid.
The start change point of the MA frame 302 is determined by the radio base station 51-
This is synchronized with the start point of the TDMA frame after the completion of the polling transmission / reception. If there is no start change point, the wireless base station 51 runs on its own clock and performs burst transmission and reception.

As described above, according to the present embodiment, the cordless subscriber circuit 17 accommodating the plurality of radio base stations 51 allows the transmission of the uplink control information from the radio base station 51 to be polled from the cordless subscriber circuit 17. Done by At this time, the change point of the start of the polling signal from the subscriber circuit 17 is matched with the start timing of the TDMA frame. Thereby, the TDMA frame phase information which the private branch exchange has in a unified manner can be transmitted to the radio base station 51. Therefore, effective use of the communication channel can be realized.

In the present embodiment, the present invention is applied to a private branch exchange. However, the present invention is not particularly limited to this, and exchange systems such as central office exchanges and key telephone systems capable of accommodating mobile communication terminals are provided. Is also applicable. Further, the number of radio base stations accommodated by the cordless subscriber circuit 17 is not limited to the present embodiment,
The frame cycle and the cycle of the burst clock are not limited to the values of the present embodiment.

[0019]

As described above, T in the mobile communication of the present invention is described.
According to the DMA frame timing information transmission system, the TDMA between the radio base station and the mobile station under the exchange is maintained while maintaining the economy of layer 1 of the cordless subscriber circuit of the exchange realizing digital mobile communication by multi-carrier TDMA.
Bursts can be synchronized. This makes it possible to use the frequency more effectively than in the case where the base stations operate asynchronously, and secure more mobile radio terminals that can be connected simultaneously in a high-traffic service area such as office use.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of a cordless subscriber circuit to which a TDMA frame timing information transmission system in mobile communication according to the present invention is applied;

FIG. 2 is a system configuration diagram when a TDMA frame timing information transmission method in mobile communication according to the present invention is applied to a digital private branch exchange;

FIG. 3 is an explanatory diagram showing an example of a signal format between the cordless subscriber circuit and the radio base station in FIG. 1,

FIG. 4 is a timing chart showing an example of a downlink channel signal transmitted to each wireless base station in FIG. 1;

[Explanation of symbols]

 17 Cordless Subscriber Circuit 19 Microcomputer 21 First Selector 23 Second Selector 51-1 to 51-4 Wireless Base Station 61 Mobile Terminal

Claims (3)

(57) [Claims] 1. A TDMA frame in mobile communication comprising a switching system, a plurality of radio base stations accommodated in the switching system, and a plurality of mobile stations communicating with the radio base stations via radio links. In the timing information transmission method, the switching system includes control means for controlling transmission and reception of signals between the switching system and the plurality of radio base stations, and is accommodated in accordance with a selection signal supplied from the control means. Selecting means for selecting a base station that permits information transmission to the mobile station from among the plurality of wireless base stations, and supplying a signal, wherein access between the base station and the mobile station is The control means is configured to transmit a polling signal that permits transmission of uplink control information from the radio base station to the switching system,
A TDMA frame timing information transmission method in mobile communication, wherein transmission is performed in synchronization with TDMA frame timing. 2. The TDMA frame timing information transmission system according to claim 1, wherein said control means determines a change point of said polling signal by TD.
A TDMA frame timing information transmission method in mobile communication, wherein the TDMA frame timing information transmission method is used as a phase synchronization timing signal of an MA frame. 3. The TDMA frame timing information transmission system according to claim 1, wherein the control circuit transmits the polling signal to the radio base station by ping-pong transmission, and a change point of the downlink ping-pong transmission signal. Is used as a phase synchronization timing signal for a TDMA frame.