JPS5860845A - Communication system - Google Patents

Abstract

PURPOSE:To prevent an increase in TDMA period when the number of subordinate stations increases, by allowing a TDMA system to use a frequency-division multiplex TDMA circuit for TDM/TDMA satellite communication. CONSTITUTION:Circuits from a master station 501 to subordinate stations 502- 510 are constituted on TDM basis, and circuits from the subordinate stations to the master stations are constituted on TDMA basis. The subordinate stations are divided into plural groups; the 1st group of stations 502-504 uses the TDMA circuits of transmission frequency f1, and the 2nd group of stations 505-507 uses the TDMA circuits of frequency f2. Similarly, different frequencies are assigned to respective groups of subordinate station. The TDM system, on the other hand, transmits only data from the master station 501 to necessary subordinate stations together with a code showing the subordinate station at destination in a TDM time slot, thus shortening a TDM frame period.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a communication method between one master station and a plurality of slave stations, and the communication from the master station to the slave stations uses time division multiplexing (hereinafter referred to as T
The present invention relates to a communication method that uses a time division multiple access (TDMA) method for communication from a slave station to a master station. .

An example of this type of communication method is time division multiplexing/time division multiple access (hereinafter abbreviated as TDMA) satellite communication, which is used for the control line of the demand assignment multiple access (hereinafter abbreviated as DAMA) method in domestic satellite communication. There is a method.

The conventional TDM/TDMA satellite communication system will be explained below with reference to the drawings. FIG. 1 is a system diagram showing an example of a TDM/TDMA satellite communication system, in which a master station 101 and N slave stations 102 to 104 A to N communicate via a satellite 105.

As shown in FIG. 1(,), from the master station 101 to the slave stations 102-
The line to 104 performs TDM communication, and as shown in FIG. 1(b), from slave stations 102 to 104 to master station
Communication using the TDMA method is performed on the line to 01. Here, "TDM" fTDMA indicates the input radio frequency of the satellite 105, and "TDM" TDMA indicates the output radio frequency of the satellite 105 corresponding to the input. In other words, generally, the transponder of the satellite converts the input frequency fi into the output frequency Fi.
Convert to

FIG. 2 shows the frame structure. FIG. 2 (,) is a TDMA frame configuration diagram, where A, B, -, and N are time slots assigned to each slave station. A slave station transmits its own burst only in its own time slot.

FIG. 2(b) is an enlarged view of the burst of slave station B.

GT is guard time, which is the time to avoid collisions between Burst comrades. DEMO5YNC is a synchronization bit for the demodulator and is a carrier and clock recovery time. UW is a unique word and is a fixed pattern for determining the bit position of data. SIC is a station identification code that indicates a slave station that is transmitting data.

DATA is data from the slave station to the master station.

FIG. 2(c) is a TDM frame configuration diagram, where UW is a unique word and is a fixed noso turn that indicates the beginning of the TDM frame and determines the bit position. A, B,...

N is two im-slots from the master station to the slave stations A, B, . . . , N.

FIG. 2(d) is an enlarged view of the time slot and shows the data from the master station to the slave station B.

The third is a system diagram of the remote station, and the operation of the master station will be explained below with reference to FIGS. 1 and 2. The upper half of FIG. 3 shows the transmitting side (TDM system), and the lower half shows the receiving side (TDMA system).

On the transmitting side, the UW indicating the beginning of the TDM frame generated by the UW generation circuit 302 and the slave stations A, B, . . .

In the N direction, data is compressed and multiplexed in a compression multiplexing circuit 301 according to the TDM frame structure shown in FIG. , is transmitted through the antenna 305 toward the satellite at a radio frequency called fTDM.

On the receiving side, FTDMA radio frequency data is received by an antenna 306, amplified and frequency-converted by an earth station receiver 307, and sent to a demodulator circuit 308.
The data is demodulated in the TDMA frame structure shown in FIG. 2 (,). The UW detection circuit 310 detects the unique word UW from this data and knows the position of the zata bit, and the SIC detection circuit 309 reads src and knows which slave station the data is from.

The separation and expansion circuit 311 separates and expands burst data and converts it into continuous data. This operation is repeated for each burst to extract data from the slave stations A, B, . . . , N.

FIG. 4 is a system diagram of the slave station, and the operation of the slave station will be explained below with reference to FIGS. 1 and 2. The upper half of Figure 4 is the transmitter side (TDMA system), and the lower half is the antenna 40 on the receiver side.
8, is amplified and frequency-converted in the earth station receiving device 409, and demodulated in the demodulation circuit '410.
Data of the TDM frame structure shown in c) is obtained. The UW detection circuit 412 detects the UW based on this data and performs TDM.
Knowing the beginning of the frame, the one-separation decompression circuit 411 performs predetermined decompression for each time slot for its own station, and extracts continuous data for its own station.

On the transmitting side, transmission data is transmitted in a compression multiplexing circuit 401 through GT and DEMO5YNC generated in a preamble generation circuit 402 and U generated in a UW generation circuit 403.
W, and S indicating the own station generated by the SXC generation circuit 404.
Together with the IC, it is compressed and multiplexed to create the own station transmission burst shown in FIG. 2(b). This transmission burst is modulated by a modulation circuit 405, frequency-converted and amplified by an earth station transmitter 406, and transmitted from an antenna 407 to a satellite at a radio frequency fTDMA.

The transmission time of this local station burst is 971 seconds after the beginning of the TDM frame received by the master station shown in FIG. 2(c). This 11 seconds is created by a delay circuit 413 inserted between the UW detection circuit 4 ] 2 and the compression multiplexing circuit 401 . Also, this value of 11 seconds means that the slave station T on the satellite
This is a semi-fixed time determined from the geographical relationship between the master station, slave station, and satellite and the TDMA frame configuration so that DMA bursts do not collide.

When the TDM/TDMA satellite communication system described above is adopted as the control line of the DAMA method in domestic satellite communication, as the number of slave stations participating in one communication system increases, TD
The MA or TDM frame period becomes longer.

Call processing performed by passing data between a master station and a slave station takes time. In other words, there is an inconvenience that the connection time for a telephone or the like becomes long and the service deteriorates.

The purpose of this invention is based on two or more considerations.

The purpose is to prevent the connection time from becoming longer due to the increase in the number of slave stations due to stale conversations, etc.

Two embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a system diagram showing one embodiment of the present invention, in which the master station 501
communicates with slave stations 502 to 510 via satellite 511.

The line from the master station to the slave station performs TDM communications, while the line from the slave station to the master station performs TDMA-based communication.

Furthermore, slave stations 502 to 504rA1, Bl, . . .

Nl) forms one TDMA line using the transmission radio frequency fl, and the slave stations 505 to 507 (A2.B2°...,
N2) constitutes a TDMA line based on frequency f2.

Similarly, slave stations 508 to 510 (AM, BM, . . .

NM) constitutes a TDMA line with nine frequencies. That is, multiple different radio frequencies ft + f 2
+ ・= + Using fy, f'c, yr TDs
MA line is available. The radio frequency of these TDMA lines.

fz +... rfy is the satellite transponder F,
・F2+..., converted to FM and received by the master station.

FIG. 6 shows the frame configuration. Figure 6(a)
is a master station reception radio frequency FlOTDMA frame structure in which slave stations Al, Bl, . . . , Nl participate. Figure 6 (
b) is the TDMA frame configuration of the master station reception radio frequency F2, in which slave stations A2, B2, ..., N2 participate. ◎Figure 6 (C) is the TD of the master station reception radio frequency FM as well.
Child stations AM, BM, . . . , NM participate in the MA frame structure. FIG. 6(d) is an enlarged view of the burst of the slave station BM, and the content is the same as FIG. 2(b). 6th
Figure (e) Id TDM frame configuration diagram, UWld
A unique word that indicates the beginning of the TDM frame and is a fixed turn that determines the bit position.
..., P are time slots from the master station to the slave stations, and the correspondence with the slave stations is not fixed. Figure 6(f) is an enlarged view of the second time slot in the TDM frame, and S
IC is a station identification code that indicates the destination slave station,
DATA is data.

Figure 7 is a system diagram of the master station. Also refer to Figures 5 and 6.
The operation of the master station will be explained below. The upper half of FIG. 7 shows the transmitting side (TDM system), and the lower half shows the receiving side (TDMA system).

Slave station specification data 70 that can arbitrarily specify whether to allocate it to a time slot on one TDM frame.
UW compressed and multiplexed according to 0 and generated by the UW generation circuit 703, and code SI indicating the destination slave station generated by the SIC generation circuit 702 according to the slave station specification data 700.
C is added, resulting in data according to the -j TDM frame structure shown in FIG. 6(e). This data is modulated by modulation circuit 704.

The signal is frequency-converted and amplified by the earth station transmitter 705, and transmitted to the antenna 706 at a radio frequency called fTDM.

On the receiving side, the satellite receives Fl ・, F2 ,...l F
Data frequency-division multiplexed at a radio frequency M is received by an antenna 707, amplified and frequency-converted by an earth station receiving device 708, and sent to a demodulation circuit 71o.

720 and 730. The data of frequency Fl is sent to the demodulation circuit 710, and the data of one frequency F2 is sent to the demodulation circuit 72.
Similarly, the frequency FM data is demodulated by the demodulation circuit 730, and the T
The data in the DMA frame is reproduced.

The UW detection circuit 712 detects the UW from the data of one frequency F1 and knows the position of the data bit, and the SIC detection circuit 7
11 reads the SICi and determines which slave station the data is from.2 Separation expansion circuit 713 separates and expands the burst-like data and converts it into continuous data.This operation is repeated for each burst, and the slave station Al.

Data is extracted from Bl, . . . , Nl. Similarly, the UW detection circuit 722 detects the UW from the data of one frequency F2.
detects and knows the position of the data bit.

The SIC detection circuit 721 reads the SIC to know which slave station the data is from, and the 2-separation decompression circuit 723 separates and decompresses the node-like data and converts it into continuous data. This operation is repeated for each burst, and slave stations A2 and B2
, . . . , data is extracted from N2. Similarly, the UW detection circuit 732 detects the UW from the two-frequency FM data.
The SIC detection circuit 731 reads the SIC to know which slave station the data is from, and the 2-separation expansion circuit 733 separates and expands the burst data and converts it into continuous data. This operation is repeated for each strike to extract data from slave stations AM, BM, . . . , NM. As a result of the above, slave station A1. B1.・
..., N1゜A2, B2, ..., N2. ...
, AM, BM,...

Extract all data from NM. FIG. 8 is a system diagram of the slave station, and the operation of the slave station will be explained with reference to FIGS. 5 and 6. The upper half of Figure 8 is the sending side (
(TDMA system), and the lower half indicates the receiving side (TDM system).

On the receiving side, radio 0 frequency FTDM data from the satellite is received by an antenna 808 and sent to the earth station receiving device 80.
9, the signal is amplified and frequency-converted, and demodulated by a demodulation circuit 810 to obtain data having the TDM frame structure shown in FIG. 6(e). The UW detection circuit 811 detects the UW from this data, knows the beginning of the TDM frame, and detects the S
The IC detection circuit 812 reads the SIC and knows the time slot for the own station, and the 1-separation expansion circuit 813 performs separate expansion from the time slot for the own station, and extracts continuous data for the own station.

The transmitting side will be explained using a slave station BM to an output radio frequency as an example. The other slave stations also operate in the same way, except for their output radio frequencies.

The transmission data j is generated by GT and DEMO5Y generated in the compression multiplexing circuit 801 and the preamble generation circuit 802.
The UW generated in the NC UW generation circuit 803 and the SI
The signal is compressed and multiplexed together with the SIC indicating the local station generated by the C generation circuit 804, and the local station transmission burst shown in FIG. 6(d) is created. This transmission burst is modulated by a modulation circuit 805, frequency converted and amplified by an earth station transmitter 806, and
It is transmitted from antenna 807 toward the satellite at radio frequency fM.

The transmission time of this local station burst is T seconds after the beginning of the TDM frame received from the master station shown in FIG. 6(,). This 12 seconds is created by a delay circuit 814 inserted between the UW detection circuit 811 and the compression multiplexing circuit 801. Also, this value of 12 seconds means that the slave station T on the satellite
This is a semi-fixed time determined from the geographical relationship between the master station, slave station, and satellite and the TDFilA frame configuration so that DMA bursts do not collide with each other.

As explained above, according to one aspect of the present invention, a TDMA system includes a plurality of TDMA lines using different radio frequencies.

That is, by using a frequency division multiplexed TDMA line, it is possible to prevent the TDMA frame period from becoming longer when the number of slave stations increases. on the other hand.

In the TDM system, only data is sent to the master station and to the required slave station in the TDM time slot with a code S indicating the destination slave station.
By adding an IC and transmitting, there is no need to prepare time slots that correspond to all slave stations, so T
It is possible to prevent the DM frame period from becoming longer.

Only 1. It is possible to suppress the connection time of telephones, etc. from increasing, and to prevent the service from deteriorating.

It goes without saying that the present invention is applicable not only to satellite systems but also to terrestrial systems or other communication systems.

[Brief explanation of the drawing]

Figure 1 is a system diagram of the conventional satellite communication system.
1 is a master station, 102 to 1o4 are slave stations, and 105 is a satellite. 2 is a diagram showing the frame structure in FIG. 1, FIG. 3 is a system diagram of the master station in FIG. 1, and FIG. 4 is a system diagram of the slave station in FIG. FIG. 5 is a system diagram of a satellite communication system according to an embodiment of the present invention, in which 5o1 master station, 502 to 510 slave stations, 511
is a satellite. Figure 6 is a diagram showing the frame structure in Figure 5, Figure 7 is a system diagram of the master station in Figure 5, and Figure 8 is a diagram showing the frame structure in Figure 5.
The figure is a system diagram of the slave stations in FIG. In FIG. 7, 700 is slave station designation data, 702 is an SIC generation circuit, and in FIG. 8, 812 is an SIC detection circuit. Figure 1 (α) (b) Mouth Figure 2 Ko = 1 piece I = = Mouth Figure 4 Figure 6 (d/) rGi DEMO5YNCLIW
SICDATA (f)

Claims (1)

[Scope of Claims] 1. A communication method between one master station and a plurality of slave stations, which uses time division multiplex lines for communication from the master station to the slave stations,
In a communication method that uses time division multiple access lines for communication from a slave station to a master station, the master station receives the plurality of time division multiple access lines using different radio frequencies and transmits data from each slave station. means for separating the time slots of the time division multiplexed circuit according to predetermined slave station designation data, and a code indicating the assigned slave station is assigned to the data for the slave station allocated 2 times in each time slot. At the same time, each slave station is provided with a means for adding and transmitting the information. The present invention is characterized by providing means for detecting a code for the own station based on the code indicating the slave station, and extracting data in a time slot in which the code for the own station is detected as data for the own station. Communication method. condescension