JPH0779305B2 - TDMA initial connection method by monitoring the acquisition area - Google Patents

Description

The present invention relates to an initial connection method for a TDMA communication system, and more particularly to an initial connection method when there are a large number of system-accepting participating stations and the communication capacity of each station is relatively small.

[Conventional technology]

In the TDMA satellite communication system, a plurality of stations share one satellite repeater by dividing it in time and perform timing control so that burst signals transmitted from each station do not overlap. For this reason, each station establishes synchronization through a reception synchronization procedure, an initial connection procedure, and a transmission synchronization procedure using a common time reference.

Conventionally, in this type of TDMA initial connection method, as shown in FIG. 5, a reference station 1 serving as a time reference generates a reference burst 2 in each basic cycle, and during the burst, a time slot for initial connection to a general station and Specify station number information and send. The reference burst 2 is, as shown in FIG.
It consists of clock recovery code CCR, reference station unique word code RUW, and control / communication signal SC. After each of the general stations T _{1 to} T _N detects the reference burst 2 from the received signal and establishes reception synchronization,
The initial connection station information is checked, and in the case of the own station, the initial connection initial transmission burst 10 'consisting of the carrier / clock recovery code CCR and the general station unique word code UW is sent to the specified acquisition area. Then, it is controlled by the delay time information from the reference station 1 or the distance is measured by the own station and the delay time is calculated to determine the transmission timing and establish the transmission synchronization. In any case, the reference station 1 manages the station numbers of the general participating stations and sequentially specifies the general station numbers during initial connection for centralized control.

[Problems to be Solved by the Invention]

In the conventional TDMA initial connection method described above, the reference station centrally manages the station numbers of the participating stations and controls them sequentially, so the control processing load of the reference station is very heavy. Further, since each general station starts the initial connection by designating the station number from the reference station, it is in a standby state until instructed. In particular, when the number of system-accommodating stations is large, the average delay time becomes very large even if the communication volume of each station is small, resulting in poor efficiency.

In view of the above-mentioned drawbacks, the technical problem of the present invention is to provide a TDMA initial connection method capable of reducing the load of the control processing of the reference station.

[Means for Solving the Problems]

The TDMA initial connection method of the present invention has means for constantly monitoring the acquisition area for initial connection at the reference station and for notifying the initial connection availability information by the reference burst in time slot units depending on the usage state. Monitoring the acquisition area, detecting the usage status from the presence or absence of the initial acquisition burst for each time slot, sending the initial acquisition burst according to the initial connection permission information from the reference station, and receiving the local station's acquisition burst. As a means to control the transmission timing by distance measurement, and as a countermeasure against the collision of the initial acquisition burst, the time slot number at the time of burst collision is made by associating the initial connection time slot number in the acquisition area with the station number of the general station. And a means for transmitting the initial acquisition burst by appropriately changing It

〔Example〕

Next, the present invention will be described with reference to the drawings. FIG. 1 shows an embodiment of the present invention in which the acquisition area is the second.
It is a system system diagram in the case of being comprised by the time slot for initial connection as shown in a figure.

The reference station 1 is a time reference of the TDMA system, and transmits the reference burst signal 2 to the satellite 3 every basic period. The burst structure of the reference burst 2 is, as shown in FIG. 3, a carrier and a clock recovery code CCR for extracting a burst signal on the receiving side, a reference station unique word code RUW for receiving timing extraction, and an initial connection of an acquisition area. Consists of a control / contact signal SC containing authorization information.

Also, the general stations T _{1 to} T _N receive the signal sent from the satellite 3 and receive the carrier of the reference burst 2 and the clock recovery code CC.
R, reference station unique word code RUW is detected to establish reception synchronization.

The reference station 1 constantly monitors the specified acquisition area 7 in the TDMA frame between the reference bursts, creates initial connection permission information for each time slot from the presence or absence of the initial acquisition burst in each time slot, and controls / contacts it. Signal
Notify each station by SC.

Similar to the base station _1, each of the general stations T _{1 to} T _N constantly monitors the acquisition area 7 to detect an unused initial connection time slot at the time of making a call request, and to receive the same time slot initial connection permission information from the base station _1. After checking, the station number of the own station is set and transmitted in the initial acquisition burst 10 (see FIG. 3) consisting of the carrier wave and the clock recovery code CCR, the general station unique word code UW and the station number STN.

After the transmission synchronization control, when the initial acquisition burst 10 in the acquisition area 7 is received and the station number of the own station is normally detected, the transmission timing is controlled to establish the transmission synchronization. If the initial acquisition burst 10 sent by the local station cannot be detected normally, it is considered that burst collision / interference has occurred in the used time slot, and the available initial connection time slot number in the acquisition area 7 is used. Based on the relationship with the station number of the own station, the centralization of the initial acquisition burst within the same time slot is distributed to other time slots and retransmitted.

As the decentralization of the initial connection time slot, the station number is normalized by the number of available time slots in the acquisition area, and is grouped by associating it with the initial connection time slot. Furthermore, by calibrating the normalization of the number of time slots while monitoring the state of burst collision within the same group, time slot allocation that avoids collision is possible.

Generally station 4 station Figure 4 is an example (T ₁ ~T _4), the initial connection time slot accession Jishon area 3 (A ₁ to A ₃₎
In this case, the time slot distribution control of the initial acquisition burst is shown when the transmission requests of each station occur simultaneously and burst collision occurs.

〔The invention's effect〕

As described above, according to the present invention, the TDMA reference station constantly monitors the acquisition area in the TDMA frame and reports the initial connection permission information in the reference burst according to the usage state. If the transmission request of the own station occurs during the initial connection permission time slot from the reference station, the initial acquisition burst is immediately sent,
By establishing transmission synchronization by looping back to the local station, the reference station does not need to manage each general station for each station, such as initial connection and synchronization control, and the load on the system control function of the reference station is greatly reduced.

In addition, when a burst collision is detected at each general station, the initial acquisition burst is dispersed in each time slot based on the relationship between the station number and the initial connection time slot number to minimize the number of burst collisions. It has the effect of effectively using the area and improving the efficiency of initial connection.

[Brief description of drawings]

FIG. 1 is a system diagram of the present invention, FIG. 2 is a diagram showing a configuration example of a TDMA frame according to the present invention, and FIG. 3 is a diagram showing configurations of a reference burst and an initial acquisition burst according to the present invention. FIG. 4 is a diagram showing an embodiment of slot distribution control of the initial acquisition burst according to the present invention, FIG. 5 is a system diagram of a conventional initial connection system, and FIG. 6 is a conventional reference burst and an initial acquisition burst. The figure which showed the structure. 1 ... Base station, 2 ... Base burst, 3 ... Satellite, CCR ... Carrier and clock recovery code, RUW ... Base station unique word code, S
C ... Control / contact signal (initial connection permission information), 7 ... Acquisition area, UW ... General station unique word code, STN ... General station number, 10,10 '... Initial acquisition burst.

Claims (1)

[Claims] 1. In a TDMA communication system in which each participating station transmits a signal in a time division to a time slot assigned to the participating station, an initial connection time slot (hereinafter referred to as an acquisition area) composed of a plurality of designated reference stations serving as a time reference. Call)
Has a means for transmitting the initial connection permission information to other general stations in units of time slots according to the usage status, and each general station receives the initial connection permission information from the reference station, However, a means for monitoring the usage status of the acquisition area and transmitting an initial acquisition burst, and if the transmitted initial acquisition burst cannot be received normally by the local station, it is considered as a burst collision / interference, and is sent to each general station in advance. Includes means for performing reacquisition by associating the set station number with the initial connection time slot number in the acquisition area to disperse the transmission time slot positions and perform reacquisition. TDMA initial connection method by acquisition area monitoring characterized by synchronous control.