JPS61202538A - Multiple access communication system - Google Patents

Abstract

PURPOSE:To improve the line utilizing efficiency even if >=2 kinds of line connection requests with different channel capacity exists by assigning each information so that a consecutive channel with large channel capacity. CONSTITUTION:In case of transmission, in general, to mobile stations 201-20n, since a band of, e.g., 5 times is required in comparison with the transmission to fixed stations 101-10n, when a transmission connection request to the fixed stations 101-10n exists, an idle channel f2 for one channel's content is retrieved from a low frequency band for assignment. When a communication connection request to the mobile stations 201-20n exists, an idle channel for 5 channel's content (e.g., a low frequency region than the f20) is retrieved from a high frequency band for assignment. In the assignment above, the line setting occupy ing one channel's content is concentrated always on the low frequency region and the line setting occupying 5 channels' content is concentrated to the high frequency region. Thus, the call loss is reduced remarkably in comparison with the conventional system where the line is set at random in this case.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a multiple access communication system in which a plurality of communication channels are shared by a large number of wireless stations.

(Technical background of the invention and its problems) In a satellite communication system, since the number of communication lines of a repeater mounted on a satellite is limited, it is necessary to use communication channels efficiently.

Therefore, a demand assignment multiple access communication system is adopted in a satellite communication system having a large number of earth stations with a relatively small frequency of 1 to 100 MHz.

In this communication method, when it becomes necessary to set up a communication line, a request is made to the line control station to allocate the line, and communication with the other station is started after receiving the line allocation from the line control station. This method is known to be highly efficient. The information to be transmitted is transmitted using the frequency division multiple access method (
Whether it is FDMA) or time division multiple access (TDMA), it is assigned to a line with a frequency bandwidth or time width depending on the intended communication.In other words, FDM
Taking example A, a radio frequency band that can transmit a baseband signal of 3.4kHz is allocated for the purpose of transmitting an audio signal, but a baseband signal of 1.5kHz is allocated for the purpose of transmitting an image signal.
It is necessary to allocate a wide radio frequency band that can transmit M1(z.Also, even if the baseband signal width is the same,
Unlike communication to a fixed station, when a large amount of radio signal power is required, such as communication to a mobile station with a small parabolic antenna, interference signals to adjacent channels increase, so it is necessary to use the required radio frequency band. It needs to be wide.

However, in the above-mentioned communication system, which handles multiple pieces of information in which the timing and connection time of line connection requests are completely random, the conventional method has been to randomly allocate lines to lines each time a request is received, regardless of communication channel capacity. Even though there are vacant channels, for example, the frequency bands of the vacant channels are not continuous, so there is a problem in that it is not possible to satisfy a line connection request that requires a wide radio frequency band. Such problems are
The same holds true for the TDMA system, and has been one of the factors leading to a decline in line efficiency and, ultimately, a decline in communication services in conventional multiple access communication systems.

[Object of the Invention] The present invention has been made based on the above-mentioned conventional drawbacks, and its purpose is to maintain line connection even when there are two or more types of line connection requests with different communication channel capacities. The object of the present invention is to provide a multiple access communication system that can improve usage efficiency and thereby improve communication services.

[Summary of the Invention] The present invention divides a communication line into a plurality of channels, and allocates information from a plurality of communication stations requiring two or more different communication channel capacities to an empty channel in response to a line connection request. The multiple access communication system is characterized in that information having a large communication channel capacity and information having the same small capacity are reversely assigned (assigned) from different positions on the frequency axis or the time axis.

〔Effect of the invention〕

According to the present invention, instead of randomly allocating channels in response to a line connection request, each piece of information is allocated so that a continuous channel with a large communication path capacity remains, so that a communication connection request for information with a large communication path capacity is It is also possible to significantly reduce call losses. Therefore, according to the present invention, it is possible to improve the line usage efficiency and improve the communication service.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

Figure 1 shows multiple fixed stations 101°10 installed on the earth.
2,,-, Ion and a plurality of mobile stations 20t,
202.

..., FDM between 20n via satellite 30
This is an example in which the present invention is applied to a satellite communication system that performs A communication. In the figure, reference numeral 40 denotes a line control station that controls line monitoring, allocation, etc. in response to line connection requests from the earth stations 101 to 10n. In this system, a plurality of fixed stations io1-10rL and mobile stations 201-20n share a line by frequency division multiplexing. The line is
As shown in FIG. 2, a control channel fA is used for exchanging control signals for communication channel allocation between fixed stations 101 to 10n and mobile stations 201 to 20n and line control station 40.

fB, fixed stations 101-10n and mobile stations 201-2
0n are divided into 24 communication channels f1 to f24 used for communication between each other.

The mobile stations 201 to 20n receive signals from partner stations using satellite communication parabolic antennas mounted on cars. Parabolic antennas cannot be made that large because they must be mounted on vehicles. Normally, the smaller the area of the antenna, the worse the signal-to-noise ratio of the received signal, so in this case it is necessary to increase the transmitting power on the transmitting side, but increasing the transmitting power also increases signal interference to adjacent channels. . For this reason,
Generally mobile station 20. 20n requires, for example, a bandwidth five times larger than that required for transmission to the fixed stations 101 to 10n. In this embodiment, one channel is allocated to line connection requests to fixed stations 101 to 10n, and five channels are allocated to line connection requests to mobile stations 201 to 20n. As shown in FIG. 2, for example, when a communication connection request is made to the fixed station 101 to Ion, one free channel (f2 in the illustrated example) is searched for from the low frequency band and allocated. Let's do it. Further, when a request for communication connection to the mobile station 20, .

If allocation is performed in this manner, line settings that occupy one channel will always be concentrated in the low frequency range, and line settings that will occupy five channels will be concentrated in the high frequency range. Therefore, in this case as well, call losses can be significantly reduced compared to the conventional system in which line settings are performed randomly.

Note that the present invention is not limited to the above-described embodiments; for example, information occupying five channels may be allocated from the low frequency region, and information occupying one channel may be allocated from the high frequency region. . Also, change the line to 2, for example.
It is also possible to divide the information into different areas and allocate information with different communication channel capacities in different directions on the frequency axis in each divided area.

In addition, the present invention is applicable not only to time division multiplexing systems but also to all types of multiple access communication, regardless of whether it is wireless or wired.

[Brief explanation of the drawing]

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 available in the system. 101~10n...Fixed station, 201~20rL...
Mobile station, 30...Satellite, 40...Line control station.

Claims (1)

[Claims] In a multiple access communication method in which a communication line is divided into a plurality of channels and information requiring two or more different communication channel capacities from a plurality of communication stations is allocated to an empty channel in response to a line connection request, the communication channel A multiple access communication system characterized by assigning large capacity information and the same small capacity information in opposite directions from different positions on the frequency axis or the time axis.