JPS6328145A - Radio communication system - Google Patents

Abstract

PURPOSE:To attain communication under the same zone radius, and transmission power for all of the service, by transmitting the signals of service whose requested transmission quality are different, by the same transmitter and with the same transmission power, and applying different improving processing of a transmission characteristic corresponding to the transmission quality. CONSTITUTION:A transmission signal is received by an antenna 8, and after it is demodulated and decoded to a baseband signal at a receiver 9, it is inputted to a signal processing circuit 11. The signal processing circuits 11 is provided by every audio signal, facsimile signal, and data signal, respectively, and after a time diversity processing is applied on each demodulation decoded signal, an error correction encoding processing is applied, and the audio signal is outputted from an audio signal output terminal 12, the facsimile signal, from a facsimile signal output terminal 13, and the data signal, from a data signal output terminal 14. In this case, the time diversity with correction codes having different correcting capability, and having different number of branches are performed on every audio signal, facsimile signal, and data signal. In this way, the higher the requested transmission quality, the more increased is the error correcting capability of the error correction code, and is increased the number of the branches of the time diversity.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a wireless communication system that provides multiple services, particularly a wireless communication system that is suitable for mobile communication systems.

"Conventional technology" When attempting to provide multiple services (e.g., voice, facsimile, data communication, etc.) in mobile communications, it is assumed that the required transmission quality (e.g., bit error rate) will vary. be done.

In mobile communications, a wireless base station connected to a fixed communication network is usually installed at the center of a service area, and mobile stations that move freely within the service area are connected to the fixed communication network via the wireless base station. . The range in which a mobile station can communicate (called zone radius) is determined by the transmission quality required for one communication and the base station/base station radius.
Determined by the mobile station's transmit power.

In general, facsimile and data communication require stricter transmission quality than voice communication, so facsimile and data communication services can be provided using the same transmitter and receiver in a system where the transmission power is set for voice communication. When users try to receive facsimile and data communications services, they are unable to receive them except near the center of the service area. Therefore, in order to perform facsimile and data communication with good quality in all areas where voice communication is possible, it is necessary to increase the transmission power by a factor Z +7 or during data communication.

It is relatively troublesome to control the transmission power for each service, and if the transmission power is controlled, it will not be necessary to increase the distance between wireless communication systems that use the same frequency, which will result in poor frequency utilization, especially In mobile radio, it is necessary to increase the distance between service areas that use the same frequency, which makes the effective use of frequencies poor.

An object of the present invention is to provide a wireless communication system that makes it possible to provide a plurality of services with different transmission qualities using the same transmitter and the same transmission power in the same station.

``Means for Solving the Problems'' According to the present invention, signals of services with different required transmission quality are transmitted by the same transmitter with the same transmission power, and the signals of the services are adjusted to the required transmission quality. Different transmission characteristic improvement processes are applied accordingly (in this case, the more severe the transmission quality required, the greater the improvement effect can be obtained).

In this way, all services can be communicated with, for example, the same zone radius and transmission power.

Embodiment FIG. 1 shows an example of a mobile communication system for explaining the present invention in detail. An audio signal input terminal 1, a facsimile signal output terminal 2, and a data signal input terminal 3 are each connected to a switch 5 via a signal processing circuit 4 for improving transmission characteristics. In this embodiment, error correction coding and time diversity are used as transmission characteristic improvement techniques, and the signal input terminals 1.2.3 are connected to error correction coding circuits 4a, 4b, and 4b in the signal processing circuit 4, respectively. The output sides of the error correction encoding circuits 4m, 4b, and 4c are connected to time diversity circuits 4d, 4e, and 4f, respectively, and these time diversity circuits 4d, 4, and 4f transmit data through a switch 5. It is switched and connected to machine 6. The transmission signal from the transmitter 6 is transmitted to the transmission antenna 7 as a smudge wave.

The radio waves are received by a receiving antenna 8 and supplied to a receiver 9. The output side of the receiver 9 is selectively connected via a switch 10 to one of the circuits corresponding to voice signals, facsimile signals, and data signals in a signal processing circuit 11 for improving transmission characteristics.

An audio signal output terminal 12 , a facsimile signal output terminal 13 , and a data signal output terminal 14 are connected to the signal processing circuit 11 .

An encoded audio signal is input to the audio signal input terminal 1 . After a check pit is added to the encoded audio signal by an error correction encoding circuit 41, the same signal is sent out multiple times at intervals by a time diversity circuit 44 (the operation of time diversity is described in a patent application 56-1
91814).

Similarly, facsimile signals and data signals are input to switch 5 through error correction encoding circuits 4b, 4a and time diversity circuits 4a, 4f, respectively. The switch 5 selects one of the voice signal, facsimile signal, and data signal and supplies it to the transmitter 6. The transmitter 6 modulates a carrier wave and transmits the signal through the transmitting antenna 7.

The transmitted signal is received by the antenna 8 , demodulated and decoded into a baseband signal by the receiver 9 , and then input to the signal processing circuit 11 . The signal processing circuit 11 is a circuit that performs the inverse of each process of the signal processing circuit 4, and is provided for each audio signal, factor i signal, and data signal, and after performing time diversity processing on the demodulated decoded signal, performs error signal processing. Correction encoding processing is performed, and the audio signal is sent to the audio signal output terminal 12.
The facsimile signal is sent to the facsimile signal output terminal 13.
The data signal is output from the data signal output terminal 14.

In this case, the present invention provides voice signals, facsimile signals,
t) The higher the required transmission quality, the higher the error correction ability of the error correction code.1
Increase the number of time diversity branches. For example, for facsimile signals as well as voice signals, the correction ability of the error correction code is enhanced and the number of time diversity branches is increased.

In this way, a plurality of services requiring different transmission qualities can be provided under the same transmission power and the same zone radius.

fi> Depending on the transmission quality requirement, only the correction ability of the error correction code or the number of time diversity branches may be different.

"Effects of the Invention" Next, the effects of this invention will be described with reference to specific examples. The audio signal is a signal tone obtained by APC-λB (adaptive prediction-adaptive bit allocation) encoding of a 3 kHz analog signal, the facsimile signal is a G3 4.8 kb/a signal, and the data signal is 2.4 kb/a. Considering the following signals, the required transmission quality for these signals is 10", 10"', and 10-, respectively.
Assume that 5. When two-branch spatial diversity (2SD) is used as a countermeasure against fading, for voice signals, when the transmission power of the base station/mobile station is 15W/3W,
In the 1.5 GHz band, the zone radius is 3 km, and the frequency allocation to the service area is realized by repeating the frequency set of 91 types. However, in the case of facsimile signals, if the transmission power is the same, the zone radius is 1.4 km. Frequency allocation to a service area is realized by repeating 36 types of frequency sets.

Therefore, as shown in FIG. 2, the audio signal from the input terminal 1 is encoded by the APC-AB encoding circuit 15 and subjected to pit selection error correction encoding (BSFEC), and the encoded audio signal is 16 kb. /s is output to switch 5. After the facsimile signal is encoded for error correction in the error correction encoding circuit 4b, it is subjected to two-branch time diversity (2TD) in the time diversity circuit 4, and is converted to 16 kb.
/m was supplied to switch 5.

Since the time diversity has two branches, one branch outputs 13 kb/s, and the third branch (8 kb/s) outputs 13 kb/s.
−4,8) kb/s is used for error correction.

The data signal at the terminal 3 was subjected to error correction coding in the error correction coding circuit 4c, and then subjected to four-branch time diversity (4TD) in the time diversity circuit 4f, and then supplied to the switch 5 at 16 kb/s. GMSK (
BbT=0.25) was modulated and transmitted. The transmission speed in the wireless section was set to 16 kb/+s. Reception is carried out by a two-branch spatial die Δ-city antenna 22, demodulated by a frequency detection 2-bit integral detection method by a transmitter/receiver ′:L1, and sent through a switch 5 to an encoding circuit 15 and a time diversity circuit 4.t4f. It was decrypted by supplying it to the fallen victim.

Using only two-branch spatial diversity in the presence of Rayleigh 7 aging at 40 Hz (2f9D)
, when using two-branch spatial diversity, two-branch time diversity, and error correction code (25D-2TD
-FEC), two-branch spatial diversity, four-branch time diversity, and error) correction code (2S
D-4TD-FEC) for each received CNR (median value) plus one average pip)! @! ! The experimental measurement results for 7 rates are shown in FIG.

As shown in Figure 3, when the received CNR is around 10 dB, an average bit error rate of 10-2 is obtained for voice signals by 2SD, and an average bit error rate of 10-4 is obtained for facsimile signals by 2SD-2TD-FEC. and the data signal is 2SD-4
An average bit error rate of 1o-5 is obtained with TD-FEC.

If the transmission characteristic improvement process shown in FIG. 2 is performed for each of the voice signal, facsimile signal, and data signal, the required transmission quality can be obtained with the same transmission power. When applied to the mobile radio, the zone radius is 3 km,
By repeating the frequency assignment to the service area through nine types of frequency sets, it is possible to provide not only voice signals but also facsimile signals and data signals.

As explained above, according to the present invention, facsimile and data communication services are possible even at locations where voice communication is possible using the same transmitter and the same transmission power, and users can use the same transmitter and transmit power without being aware of the differences in services. You can receive several services. This invention is applicable not only to mobile communications but also to general wireless communications.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a wireless communication system to which this invention is applied, Fig. 2 is a block diagram showing an example of an experimental system to which this invention is applied, and Fig. 3 is a block diagram showing an example of an experimental system to which this invention is applied. FIG. 3 is a diagram showing experimental results of the relationship between rate and received CNR.

Claims (1)

[Claims] (1) A method of providing multiple services with different required transmission quality through wireless communication, in which wireless communication is performed using the same transmitter with the same transmission power for each of the above services, and the required transmission quality of the above services is A wireless communication system characterized in that the service signal is subjected to transmission characteristic improvement processing that provides a greater improvement effect as the requirements for transmission quality become more severe.