JPH0677942A - Diversity selecting and switching system - Google Patents

Abstract

PURPOSE:To provide the TDMA(time division multiple access) transmitting system diversity selecting and switching system which is simple and hardly affected by phasing. CONSTITUTION:On the transmission side, an encoding means 1 performs error correction encoding to transmitting data, and the same data are repeatedly transmitted by using a time slot different for the TDMA transmitting system. On the reception side, the respective data are received by plural reception parts 5a and 5b and stored in memories 6a and 6b. The data from the respective memories 6a and 6b are switched and selected by a switching part 7 for each time slot so as to provide one data sequence. These data are decoded by a decoding part 8, and less error rate data are selected by a comparison part 9, and comparative data (source data) are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to time diversity by repeatedly transmitting the same data on the transmitting side, receiving it by a plurality of receivers, and selectively switching data having a small correlation with each other. The present invention relates to a diversity selection switching method having a function of space diversity.

[0002]

2. Description of the Related Art Diversity reception according to the prior art utilizes a plurality of received signals with low correlation in order to reduce the effects of multipath fading, rain attenuation, etc., and when one of the received levels drops, the other This is a technique for maintaining a good received signal quality by using the received wave.
There are a selection method for selecting a higher-level reception wave according to the reception level, and an equal gain combining method for combining the reception waves after making all the reception wave phases in phase. The combining method needs to match the phases of the received signals, and is difficult to apply to mobile communications in which the received waves fluctuate at high speed. Although the selection method is inferior to the synthesis method in characteristics, the selection method is often used because it can be easily realized.

In addition to this, there is a time diversity system in which the same data is repeatedly transmitted at different times.

[0004]

However, in the space diversity using the above-mentioned conventional selection method, a delay occurs at the time of selection switching and it is not possible to follow the fluctuation of the reception level, so that a sufficient diversity effect can be obtained. There was a problem of not having. Further, since only the signal for one branch having the highest reception level is always received and processed, even if a signal having a high level is received by another branch, there is a problem that the signal cannot be used.

Further, a space diver using the conventional selection method
In Siti, there is a problem that a plurality of error correction and error detection decoders are required to obtain the reception data for each receiver, which complicates the configuration of the apparatus.

Further, in the time diversity receiving system, if the repetition time interval of the transmission data is short, the temporal correlation becomes large, and a sufficient diversity effect cannot be obtained with the data having a short block length. There was a problem.

The present invention has been made in view of the above points, and an object of the present invention is to eliminate the above-mentioned problems and to provide a diversity selection switching system that is simple and is not easily affected by fading.

[0008]

In order to solve the above-mentioned problems, the present invention applies the error correction coding to the transmission data by the coding means 1 on the transmission side as shown in FIG. TDM
A (time division multiple access) transmission method is used to repeatedly transmit using different time slots. On the receiving side, a plurality of receiving sections receive the respective data and store the received data in the memory 6
It is stored in a and 6b. Memory 6 for each time slot
The data from a and 6b are switched and selected by the switching unit 7 to obtain one data sequence (S2 in FIG. 2). This data is decrypted by the decoding unit 8
Means for obtaining the comparison data S4 (source data) by selecting data having a smaller error rate in the decoding unit 8 (S3 in FIG. 2).

[0009]

According to the present invention, the same data is transferred to the TD by the above method.
Data transmitted using different time slots by the MA (Time Division Multiple Access) transmission method, and data received by different receivers are selected, so that data having a small correlation with each other in terms of time and space is obtained. -You can select the data. Therefore, high quality data can be obtained by comparing these two data and obtaining data with few errors.

In this system, since data is always received from all the branches and the data with the smallest error is selected, there is no problem that the fluctuation of the reception level cannot be followed by the conventional switching delay. Further, the data can be decoded by one decoder by the above means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. As shown in the figure, in the diversity selection switching system of the present invention, the transmitting side is composed of encoding means 1, transmitting means 2 and transmitting antenna 3, and the receiving side is receiving antenna 4a, receiving antenna 4b, receiving section 5a, receiving. Part 5b, memory 6
a, a memory 6b, a switching unit 7, a decoding unit 8, and a comparison unit 9.

FIG. 2 shows the flow of data until the transmission data is received and determined. In this embodiment, (7,4) BCH is used as an example of the error correction code, and 2-channel TDM is used.
A transmission will be described. Coding means 1 on the transmitting side codes the transmission data to enable error correction and error detection at the time of reception. In this example, since the code length of the code is 7 bits, each symbol shown in FIG. 2 corresponds to 7 bits.

In this system, the same data is transmitted twice in different time slots in the TDMA transmission system in order to obtain the effect of time diversity. That is, d1 and d2, d3 and d4, d5 and d6, d7 and d of the transmission data S1 of FIG.
8 is the same data respectively.

The transmission data S1 (d1 to d8) is received by the reception antennas 4a and 4b, demodulated by the reception units 5a and 5b, AD-converted, and the reception data shown in FIG.
Data S1a (A1 to A8) and S1b (B1 to B8). Since the number of bits of data in one time slot is set to 7 bits, these received data S1a (A1 to A1
8), and the data corresponding to the symbols S1b (B1 to B8) are stored in the memory units 6a and 6b as 7 bits.

Reception data stored in the memory units 6a and 6b.
The data S1a and S1b are sequentially output, and the switching unit 7
Switching data S2 (A1 to B8) which is switched bit by bit
Is obtained. When switching, A1 and B, which have a small spatial correlation
2, A3 and B4, A5 and B6, A7 and B8 (or B1
And A2, B3 and A4, B5 and A6, and B7 and A8) may be selected as switching data S2. The decoder 8 decodes the switching data S2 by using the error correction code, and the decoded data S
3 and the error rate (the number of error bits) are output to the comparison unit 9.

The decoded data S3 (D1 to D8) has two consecutive data obtained from the same transmission data. Two consecutive decoded data (D1 and D2, D3 and D4, D5 and D6, D7 and D8) are compared by the comparison unit 9, and the comparison data S4 (for example, D1, D3, D5, D) having less error is compared.
7) is selected. As the selection means, error detection is performed by an error correction code, the error rate (number of error bits) of each continuous data is obtained, and this error rate is input to the comparison section 9 and used as a reference for selection.

As other selection means, means for comparing the reception levels of the receivers to select data received by the receiver having a high reception level, or phase information having a high likelihood using phase information. You may use the means to select.

[0018]

As described above in detail, according to the present invention, the following effects are expected. A code that enables error detection and error correction on the transmission side is added to the transmission data, and TD
The MA (time division multiple access) transmission method is repeatedly transmitted using different time slots, and data received by different receivers are selected so that there is little correlation with respect to time and space. Data can be selected. Therefore, high quality data can be obtained by comparing these two data and obtaining data with few errors. Also, in this system, since data is received from all branches at all times and data with the least error is selected, there is no problem of being unable to follow the received level fluctuation due to the conventional switching delay. Moreover, the configuration is simple with one decoder.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a diversity selection switching system of the present invention.

FIG. 2 is a diagram showing a flow of data until transmission data is received and determined.

[Explanation of symbols]

 1 Encoding means 2 Transmission means 3 Transmission antenna 4a Reception antenna 4b Reception antenna 5a Reception section 5b Reception section 6a Memory 6b Memory 7 Switching section 8 Decoding section 9 Comparison section

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Claims (2)

[Claims] 1. In a diversity selection switching system of a TDMA transmission system having an error correction coding means and comprising a plurality of receiving means, a code for error detection and correction in transmission data on a transmission side is provided. In addition, a means for repeatedly transmitting the same data by using different time slots in the TDMA transmission system is provided, a plurality of receivers are provided on the receiving side, and the repeatedly transmitted data is different from each other. These data are received by the receiver.
A synthesizing means for selectively switching data and synthesizing into one data series is provided, and a decoding means for decoding the data synthesized into one data series by the synthesizing means is provided, and each decoded data is provided. The diversity selection switching system is characterized in that a means for selecting the error rate of each of them, comparing the error rates, and selecting the data with the least error is provided. 2. The diversity selection switching system of the TDMA transmission system according to claim 1, wherein each of the plurality of receiving units is provided with a unit for obtaining a receiving level, and the receiving unit receives a high receiving level from the decoded data. A diversity selection switching system characterized by comprising means for selecting data of the means.