JPH02217027A - Guard time setting system for time-division multiple connection - Google Patents

Abstract

PURPOSE:To prevent time using efficiency from being deteriorated due to guard time and to optionally setting up the size of a radio zone by transmitting a signal for specifying the guard time between burst signals for executing time- division multiple connection from a radio base station to a mobile station. CONSTITUTION:In mobile communication using time division multiplex connection constituting a service area of plural radio base stations (MBSs) to access each MBS from plural mobile stations (MSSs), a communication channel consisting of a burst-like signal is formed between the MBS and the MSS and guard time 35 between burst signals is set up so that plural burst signals sent from the plural MSSs having respectively different distances from the MBS are not superposed in the MBS. A signal for specifying the length of the guard time 35 is inserted into a control signal 33 to be informed from each MBS to respective MSSs. Consequently, the guard time 35 corresponding to the size of each radio zone can be set up.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a burst communication system in a mobile communication system in which a wireless base station and a mobile station are connected using a multi-channel access function based on a time division multiple access system. This relates to a guard time setting method between signals.

[Conventional technology]

Multiple mobile stations (MSS) in one wireless base station (MBS)
In a mobile communication system using the time division multiple access (TDMA) system, in which the service area is configured by multiple MBSs, the MBS accesses the MBS.
It is necessary to form a communication channel consisting of burst signals between the BS and the MSS. In this case, in order for multiple MSSs to access one MBS, it is necessary to set a guard time between burst signals so that the burst signals transmitted from multiple MSSs at different distances from the MBS do not overlap at the MBS. be. The guard time for this needs to be set to be greater than the difference in arrival time at the MBS of the burst signal between the MSS closest to the MBS and the MSS farthest from the MBS (hereinafter referred to as the maximum arrival time difference); the larger the maximum arrival time difference, the more the guard time It is necessary to set a large time. Note that the smaller this guard time is, the less the temporal utilization rate of radio waves will decrease.

Conventionally, the maximum arrival time difference in a system consisting of a plurality of MBSs has been fixedly set assuming the largest service area (wireless zone) covered by one MBS. Therefore, even in a system where large and small wireless zones coexist, especially when the wireless zone is large, the maximum arrival time difference is assigned to the original transmission signal due to the fixed guard time setting that takes into account the largest wireless zone. This method has the drawback of causing a decrease in the frequency utilization rate due to a decrease in the time utilization rate due to the decrease in the time rate.

[Means for Solving the Problem] In order to eliminate such conventional drawbacks, the present invention inserts a signal instructing the length of guard time into the control signal broadcast from each MBS to each MSS. By doing so, it is possible to set the guard time according to the size of each wireless zone.

[Effect]

In areas with high subscriber density, frequency utilization can be improved by reducing the size of the wireless zone and also reducing the guard time. On the other hand, in areas with low subscriber density, a large wireless zone can be tolerated by setting a large guard time. In this way, the present invention can arbitrarily set the size of the wireless zone of a mobile communication system using the TDMA system while preventing a decrease in the time utilization rate due to guard time.

〔Example〕

Figure 1 shows a wireless base station (MB) used when implementing this invention.
FIG. 2 is a block diagram showing a configuration example of a mobile station (MSS) and a mobile station (MSS). In the figure, 11 is an antenna, 12 is an antenna duplexer, 13 is a receiving section, 14 is a transmitting section, and 15 is a local oscillator whose oscillation frequency is changed by a signal from a frequency control circuit 16 to connect the transmitting section 14 and the receiving section 13. A circuit 17 for supplying a single signal is a TDMA terminal section that creates and controls a TDMA signal consisting of a burst signal between the MBS and the MSS.

FIG. 2 is a block diagram showing an example of the configuration of the TDMA terminal unit 17. In the figure, 21 is a modulator, 22 is a demodulator, 23 is a multiplexing unit, 24 is a preamble generation unit that generates preamble signals other than original traffic data such as frame signals and control signals, and 25 is a preamble processing unit. 26 is a frame signal detection unit that detects a frame synchronization signal, 27 is a synchronization/timing control unit that controls synchronization/timing, 28 is a traffic data generation unit, and 29 is a traffic data processing unit for extracting necessary traffic data. Department.

FIG. 3 shows an example of a burst frame configuration of a TDMA signal showing the relationship between a burst signal and guard time in TDMA. 31 is a carrier wave and an unmodulated carrier wave necessary for clock synchronization CR132 is a frame signal F necessary for frame synchronization
R233 is a control signal for transmitting and receiving necessary control information between MBS and MSS 5C134 is traffic data TD necessary for telephone calls, etc. 35 is a guard time GT between burst signals from multiple MSSs, 36 is a mobile station ( MSS)
37 is a preamble signal from the base station (MBS). Here, guard time GT
must be greater than the burst arrival time difference from the nearest and farthest mobile stations to the MBS, and if the radio zone radius is R (km), the guard time G'F is the minimum GT
=2 RXIO3/ 8 Xl0I'=6.7 R(μ
sec), and this time is TDM within one frame.
If the multiplicity of the A/<-st signal is M, then ('rD) corresponds to XMX6.7 R (bit), and TD
The time utilization rate of MA signal is (TD)/(CR+PR
+SC+TD+(TD)XMX6.7R). As a result, the shorter the guard time GT and the smaller the radius R of the wireless zone, the better the temporal utilization rate of the TDMA signal will be.

The operating principle of this invention will be described below. TDM shown in Figure 2
In the A terminal section, traffic data from the fixed network or the terminal is added with preamble signals (CR, FR, SC) in the multiplexing section 23 and converted into complete TDMA data.
It becomes a burst, is modulated, and is output from the TDMA terminal section. On the other hand, after the received TDMA burst signal is demodulated, the FR of each received burst is detected by the frame signal detection section 26, and this timing provides a time reference for processing the received burst. F of each burst
Preambles other than R are processed by the preamble processing section 25. Each piece of traffic data is subjected to necessary multiplexing and demultiplexing in a traffic data generating section 28 and a processing section 29. Here, this MBS
Instructs each MSS to send a signal specifying the guard time of the TDMA burst signal constituted by the TDMA burst signal.
The preamble processing section 25 of the DMA terminal section receives the guard time designation signal and passes the signal to the synchronization/timing control section 27 to adjust the timing of the modulator 21, thereby adjusting the time between burst signals from each MSS. control the guard time.

Furthermore, in a system that performs transmission output control as the guard time designation signal from the MBS, the transmission output control signal can also be used as the guard time designation signal.

〔Effect of the invention〕

As explained above, according to the present invention, in a mobile communication system using a time division multiple access (TDMA) system, the guard time between TDM^ burst signals from multiple MSSs can be controlled by the MBS. The distance to the MSS can be controlled, that is, the guard time can be set according to the size of the wireless zone. As a result, wireless zones of different sizes can coexist within the same system, and there is an advantage that the same system can cover areas from large cities to rural areas.

Furthermore, if the number of subscribers increases after the system is introduced, the size of the wireless zone can be reduced while reducing the guard time, and there is also the advantage that the system can be operated flexibly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the configuration of a radio base station and a mobile station, FIG. 2 is a block diagram showing an example of the configuration of a TDMA terminal section, and FIG. 3 is a diagram showing an example of a burst frame configuration of a TDMA signal. Patent applicant Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] (1) In a mobile communication system in which communication is performed between a radio base station and a mobile station using a time division multiple access method, the guard time between burst signals that perform time division multiple access from the radio base station to the mobile station is A guard time setting method for time division multiple access, characterized in that the guard time is made variable for each radio zone covered by each radio base station by transmitting a designated signal.