JPH0650843B2 - Multiple access communication method - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a multiple access communication system in which a plurality of wireless stations share a plurality of communication channels.

[Technical background of the invention and its problems]

In the satellite communication system, the number of communication lines of the repeater mounted on the satellite is limited, so it is necessary to use the communication channels efficiently.

Therefore, in a satellite communication system having a large number of earth stations with relatively low traffic, a demand assign multiple access communication system is adopted.

This communication method requires the line control station to allocate the line when the necessity of setting the communication line arises, and the line control station receives the line allocation before communicating with the partner station. It is known as a highly efficient method.
The information to be transmitted is time division multiple access (TDMA) or frequency division multiple access (FDMA).
However, it is assigned to a line having a frequency bandwidth or time width according to the intended communication. That is, FD
Taking MA as an example, a radio frequency band capable of transmitting a baseband signal of 3.4 kHz is allocated for the purpose of transmitting an audio signal, but a baseband signal of 1.5 MHz is assigned for transmitting an image signal.
It is necessary to allocate a wide radio frequency band capable of transmitting the signal. Also, even if the baseband signal width is the same, if it is necessary to use a large amount of radio signal power as in the case of communication to a mobile station with a small parapolar antenna unlike communication to a fixed station, interference with adjacent channels As the number of signals increases, it is necessary to make the required radio frequency band wide.

However, in the above communication system that handles a plurality of pieces of information in which the timing and the connection time of the line connection request are completely random, the line allocation request has been made randomly every time the request was made without distinction of the communication path capacity. Has a problem that it is not possible to satisfy the line connection request that requires a wide radio frequency band because the frequency channels of the empty channels are not continuous, although the empty channels are scattered. . Problems like this
The same is true for the TDMA system, which is one of the factors that lead to a drop in line efficiency and a drop in communication services in the conventional multiple access communication system.

[Object of the Invention]

The present invention has been made on the basis of such conventional drawbacks, and an object thereof is to improve the utilization efficiency of lines even when there are two or more types of line connection requests having different communication channel capacities. Therefore, it is intended to provide a multiple access communication system capable of improving communication services.

[Outline of Invention]

According to the present invention, a communication line is divided into a plurality of frequency-divided or time-divided channels, and information that requires two or more different communication channel capacities from a plurality of communication stations is provided to each of the empty channels of the communication line. In the multiple access communication method in which communication is performed by allocating, of the information having different communication channel capacities, information having a large communication channel capacity is sequentially allocated to empty channels from one end side on the frequency axis or the time axis, and communication channel capacity is small. The information is characterized in that it is sequentially assigned to empty channels from the other end side on the frequency axis or the time axis.

〔The invention's effect〕

According to the present invention, instead of randomly allocating channels according to a line connection request, each information is allocated so that continuous channels having a large channel capacity remain, so that a communication connection request for information having a large channel capacity is made. Also, the call loss can be greatly reduced. Therefore, according to the present invention, it is possible to improve the utilization efficiency of the line and improve the communication service.

Example of Invention

Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

Fig. 1 shows multiple fixed stations 10 ₁ , 10 ₂ , installed on the earth.
, 10 _n and a plurality of mobile stations 20 ₁ , 20 ₂ , ..., 20 _n are examples in which the present invention is applied to a satellite communication system for performing FDMA communication via a satellite 30. 40 in the figure
Is a line control station that controls line monitoring, allocation, etc. in response to line connection requests from the earth stations 10 ₁ to 10 _n . In this system, a plurality of fixed stations 10 ₁ to 10 _n and mobile stations 20 _{1 to} 20 _n share a line by frequency division multiplexing. The lines are fixed stations 10 ₁ to 10 _n as shown in FIG.
And control channels f _A and f _B used for communicating control signals for communication channel allocation between the mobile stations 20 _{1 to} 20 _n and the line control station 40, and the fixed stations 10 ₁ to 10 _n and It is divided into 24 communication channels f1 to f24 used for communication between the mobile stations 20 _{1 to} 20 _n .

Each of the mobile stations 20 _{1 to} 20 _n receives a signal from the other station by using a satellite communication parapolar antenna or the like mounted in the vehicle.
The para-polar antenna cannot be made so large because it is mounted on the vehicle. Normally, as the area of the antenna becomes smaller, the SN ratio of the received signal deteriorates. In this case, therefore, the transmission power of the transmission side must be increased. However, if the transmission power is increased, signal interference with adjacent channels also increases. . Therefore, in general, when transmitting to the mobile stations 20 _{1 to} 20 _n , the fixed station
For example, a bandwidth of 5 times is required as compared with the case of performing transmission to 10 ₁ to 10 _n . In this embodiment, fixed stations 10 ₁ to 10 _n
One channel is allocated to the line connection request to the mobile stations, and five channels are allocated to the line connection request to the mobile stations 20 _{1 to} 20 _n . Then, as shown in FIG. 2, for example, a fixed station
When there is a request for communication connection to 10 ₁ to 10 _n , an empty channel for one channel from the low frequency band (in the illustrated example, f
2) Search and make an assignment. In addition, mobile stations 20 _{1 to} 20
_{When there} is a communication connection request to _n , 5 from the high frequency band
An empty channel for the channel (a frequency range lower than f20 in the illustrated example) is searched and assigned.

If the allocation is performed in this manner, the line settings that occupy one channel are always concentrated in the low frequency region, and the line settings that occupy five channels are concentrated in the high frequency region. Therefore, in this case as well, the call loss can be greatly reduced as compared with the conventional method in which the line setting is randomly performed.

It should be noted that the present invention is not limited to the above embodiment, and for example, information occupying 5 channels may be allocated from the low frequency region, and information occupying 1 channel may be allocated from the high frequency region. . Alternatively, the line may be divided into, for example, two pieces of information, and information of different communication channel capacities may be assigned to different directions on the frequency axes in the respective divided areas.

In addition, the present invention can be applied not only to the time division multiplex system but also to any multiple access communication regardless of wireless or wired.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a satellite communication system according to an embodiment of the present invention, and FIG. 2 is a diagram showing channel frequencies in the system. 10 ₁ -10 _n ...... Fixed station, 20 ₁ -20 _n ...... Mobile station, 30 ......
Satellite, 40 ... Line control station.

Claims (1)

[Claims] 1. A communication line is divided into a plurality of frequency-divided or time-divided channels, and information from a plurality of communication stations, which requires two or more different communication channel capacities, is set in an empty channel of the communication line. In the multiple access communication method in which communication is performed by allocating each, among the information with different communication channel capacities, information with large communication channel capacity is sequentially allocated to empty channels from one end side on the frequency axis or the time axis, and the communication channel capacity A multiple access communication method characterized in that small information is sequentially assigned to empty channels from the other end on the frequency axis or the time axis.