JPS5899044A - Transmission time control system for time division multiplex communication system - Google Patents

Abstract

PURPOSE:To set a timing time for return signal transmission accurately without interference, by setting said timing time from a slave station through the use of a burst signal having a shorter time width than the time slot width addressed to the slave station. CONSTITUTION:A frame including a plurality of time slots is generated from a transmission frame generating section 5 of a central station 1 and transmitted from a transceiver 6. This signal is received at a frame transceiver 12 via a transceiver 11. A slave station 2 receiving a time slot T1 transmits a burst signal Tss smaller and shorter than the time width of the time slot to the reception time slot T1 after a prescribed time t0 after a time tx. Even if the value of the return timing time tx has an error, the shorter burst signal is fluctuated only in the reception time slot of the central station 1 and no interference is given to adjacent time slots Tn, T1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Description of the technical field to which the invention pertains] The present invention relates to a time division multiple access (TDMA) communication system. In particular, it relates to control of transmission times at which slave stations scattered around one central station transmit signals in time slots assigned to themselves.

[Description of prior art]

In the time division multiple access communication system, as shown in FIG. 1, slave stations 21 to 2 are scattered around a central station 1. Each slave station 2. 2s and the central station 1 are different, so the radio wave propagation time between each slave station 21 to 2s and the central station 1 is different.

FIG. 2 is a diagram showing the structure of a frame in a time division multiple access system. In the same figure, 11, ν2 is a frame tear (each frame has multiple time slots)? It is time-divided into + to Tn.

Here, the slave stations 21 to 2stj shown in FIG. 1, the plurality of time slots T1 to Tn (F) 1 shown in FIG.
However, the burst signal must be sent by considering the propagation time so that it is received at the central station 1 at the correct time. Moreover,
As described above, since the propagation time to the central station l differs for each slave station 21 to 23, the burst transmission timing differs for each slave station 21 to 25.

If this timing is incorrect, interference will occur in adjacent time slots shown in FIG.

Traditionally, this lumber timing control is well known as an implementation of the TDMA method for satellite communications.

That is, when using this timing, radio waves at a level sufficiently lower than the normal transmission output are once continuously transmitted, and a signal having a specific pattern is transmitted for each frame. The satellite relay station sends the received signal back to the sending ground station, and the ground station receives the signal sent back. (Scheduled time slot) Check that the specific pattern that appears in K is received. From K, you will know the timing of your own station's transmission. Once this timing is known, the transmitter is activated and the burst signal is sent out only in the time slot in which the own station should send out the signal, in accordance with this timing. In a satellite, the radio wave propagation time between the ground station and the satellite station can be considered free space, and the distances between the satellite and multiple ground stations can all be considered constant, so the time slots used by other ground stations can be considered as free space. It is harmful to transmit at a low enough transmission level so as not to cause interference.

However, when implementing this TeDM system on the ground, Ka,
Each slave station 2. The radio wave propagation time between ~2s and the central station 1 varies depending on the topographical conditions, so the timing must be set at a sufficiently low level so as not to interfere with the time slots used by other slave stations. Sending a signal is separate from society.

[Object of the present invention]

The present invention improves this point by accurately determining the signal transmission timing from the slave station to the central station in order to transmit a short burst data signal from the slave station within the scheduled time slot at the central station. It is an object of the present invention to provide a transmission time control method that can transmit data without interfering with adjacent time slots.

[Summary of the Invention] The present invention provides a time division multiplex multiple access system consisting of a large number of slave stations and a central station, in which a slave station that receives a frame synchronization signal sent from the central station changes the transmission time from this time. means for transmitting a burst signal longer than a predetermined time slot length to a central station for control purposes; and time difference information between the central station receiving the burst signal and a predetermined time slot to be received; and means for transmitting the data to the slave station, and is characterized in that the slave station is controlled to modify the time at which the slave station transmits the data to the central station.

[Explanation based on examples]

An embodiment of the present invention will be described based on the drawings.

FIG. 5 shows a block diagram of a main part of the central station 1 according to an embodiment of the present invention, and FIG. 4 shows a block diagram of a main part of a slave station (eg 2.) according to an embodiment of the invention.

In FIG. 3, 5 is a transmission frame generator, the output of which is led to a transceiver 6. This transmission frame occurs 1)
5, the output of the time generator ls7 is led. Moreover, the output of this time generator 7 is pulse oscillation 1! i, 8 and pulse number counter 9, respectively. The outputs of the pulse oscillator 8 and the burst signal detector IO are led to the pulse number counter 9, respectively. The output of this pulse number counter 9 is led to the transmission frame generator 5. Further, the output of the transceiver 6 is guided to a burst signal detector 10.

In FIG. 4, U is a transceiver whose output is led to a frame transceiver 12. The output of this frame transmitter/receiver 12 is guided to the transmitter/receiver IIK via a burst signal transmission time setting device 13. Further, the output of the frame transceiver ν is guided by the human control of the burst signal transmission time setting port.

FIG. 5 is a diagram showing the time relationship of signals between the central station 1 and the slave stations 2 in the above embodiment. In Figure 3, MuTX t
d The transmission of the central station l, Muyu indicates the timing of the 9th signal of the central station l. The BRX in the figure is slave station 2. Reception, 13'rx is Chibato 2. The transmission timing of each is shown below.

In addition, in the figure, td is the propagation time to the slave station 2, and ζ is the propagation time to the slave station 2. receives the receive time slot T1 and then the central station l
to is the transmission timing time of the burst signal tss, which is a characteristic of the present invention, and ti3 is the return timing time to the slave station 2 after transmission from the central station l. The timing time until receiving the time slot T from T, respectively is shown.

6 is an operation time chart showing the human power or output signal waveform at the points indicated by X marks in FIG. 5.

With such a circuit configuration, a frame including a plurality of time slots τ, -Tn is generated from the transmission frame generator 5 of the central station 1, modulated to a radio frequency by the transceiver 6, and transmitted over the antenna. In the slave station 21, this frame signal is transmitted via the transmitter/receiver 11, as indicated by a square. At this time,
Frame 1 transmitted from central station l. Time slot T, Fi slave station 2. It arrives after a propagation time t, 1 has elapsed. As shown in FIG. 1, slave stations 21 to 2. Since the distances to the central station 1 are all different, the propagation times t,1 are also different. Time slot T sent out from central station l as shown in FIG.

The slave station that received 2. is sent to the central office 1 in time slot T, IIC after one hour. At this time, it is difficult to measure the transmission time (fK) with high precision, and the general method is to measure it on a map. The time slot from the slave station 2 sent toward the credit time slot TE of the central station 1?, #i adjacent time slot Tn%T, K
May cause interference.

Here, the feature of the present invention is that the time slot τ occurs after a certain period of time after the elapse of the time tX.

A short burst signal t, , smaller than the time width of the center wJ
The signal is sent to the reception time slot T of 1. By doing this, even if there is an error in the value of the return timing time t, the short burst signal te
Since a varies only within the receiving time slot T of the central station 1, it does not interfere with the time slot Tn%T2 of the phase II selection.

Here, FIG. 7 shows the relationship between the receiving time slot T at the central station l and the short burst signal ts+s. When the time of the receiving time slot T is tw, the short burst signal tea is transmitted from the slave station 2 to the central station 1 accurately at a time of 1. become the center of However, when the time slot T is 300 μm θC and the length of the burst signal t0 is 100 μsec, the transmission timing time t of the burst signal “8.” is 100 μ8θC.
It is said that

That is, slave station 2. After receiving the time slot T from the central station 1, the burst signal transmission time setter 13 adjusts the time to tX'-t, (2t4+to), and then transmits the burst signal tas to the central station 1.

On the other hand, the central station 1 is connected to the slave station 2. At the same time as time slot T1 is sent to time slot T1, trigger signal d is sent from time generator 7 to Norx oscillator 8 and pulse number counter 9.

Send out. From this K, a pulse signal d is sent to the pulse oscillator 8Fi and the pulse number counter 9, and the pulse number counter 9 counts this number.

The burst signal t is detected by a burst signal detector 10 through a transceiver 6 of the central station 1. Nokuichi burst signal detector 10 companies burst signal tf1. When all the pulses are detected, the detection pulse signal 64 is sent to the pulse number counter 9 to stop the counting operation. At this time, the count value of the pulse number counter 90 is sent to the transmission frame generator 5 and sent to the primary slave station 21 in the time slot from T and K to the slave station 2. sent to. Child station 2. The time t' of the burst signal sending time setter 13 is adjusted using this value, and the burst signal tBIB is sent to the central station 1 again at the adjusted timing ζ'.

5 Hereafter, this operation is performed using the burst signal t11. is received at the center of time 1.0 of time slot T of central station l shown in FIG. With this pressure, slave station 2
The return timing time tX of one time slot T1 is accurately set in the burst signal transmission time setter 13.

[Explanation of effects]

KJl:mQ As explained above, according to the present invention, the setting of the return signal transmission timing time from the slave station to the central station is
We decided to use a burst signal with a time width shorter than the time slot width for the slave station.

Therefore, it is possible to accurately set the return signal transmission timing without causing interference to adjacent time slots.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a time division multiple access system. FIG. 2 is a signal frame configuration diagram used in the system shown in FIG. 1. FIG. 5 is a block diagram of main parts of a central office according to an embodiment of the present invention. FIG. 4 is a block diagram of main parts of a slave station according to an embodiment of the present invention. FIG. 5 is a diagram showing the state of signal transmission and reception between the central station and slave stations in the above embodiment. FIG. 6 is an operation time chart showing input or output waveforms at points indicated by crosses in FIG. FIG. 7 is a diagram showing the reception timing of burst signals. 1... Central office, 2. ~23...Slave station, 5...Transmission frame generator, 6.11...-Transmitter, 7...Time generator, 8...-Pulse oscillator, 9...Pulse number counting 10...Burst signal detector, U...Frame transmitter 9, 13...Burst signal sending time setting device. Patent applicant: NEC Corporation. Agent Patent Attorney Takashi Ide 1, i・?・Go to I; PI Figure 2 Figure 4

Claims (1)

[Claims] (1) A frame signal containing multiple time slots is transmitted from one central station to multiple slave stations, and each slave network receives the time slot signal addressed to it from the above time slots. K. In a time division multiplex communication system in which each slave station transmits a signal in a time slot assigned to it so as to constitute a frame signal at a central station,
Each slave station is equipped with means for transmitting a burst signal shorter than the time slot length addressed to the own station to the central station, and a burst signal sending time setting means for setting the transmission timing time for transmitting this burst signal, and the central station (1) means for transmitting time difference information between the reception timing of the bust signal and a predetermined standard reception timing to each station; and further to the slave station. A transmission time control system for a time division multiplex communication system, characterized in that it comprises means for controlling the setting time of the burst signal transmission time setting means so that the burst signal is received at the predetermined nine-signal timing based on the deviation time information. One-sided.