JPH0298245A - Route identification system - Google Patents

Abstract

PURPOSE:To improve line transmission efficiency by providing a coder applying error correction coding to a data signal to be transmitted and a specific bit inverter inverting the bit of a predetermined position of the error correction code word to a sender side and differentiating the bit location to be inverted for word synchronization at every route. CONSTITUTION:A forward error correction(FEC) coder 1 applies error correction coding to a data signal to be transmitted into a block code and a specific bit inverter 2 inverts the bit of a specific position of each code word inputted from the FEC coder 4 and outputs the result to a modulator 3. The specific location of bit inversion is set different from each route corresponding to the route identification code representing each route in the digital radio communication system. The modulator 3 sends a modulation signal modulated by an inputted data signal to a radio circuit. Thus, the route identification is attained without sending a special bit such as a route identification code and the transmission efficiency of the line is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a route identification method, and more particularly to a route identification method in a digital wireless communication system.

[Conventional technology]

In a wireless communication system, the received electric field decreases due to fading, and there is a possibility that interference signals from other routes, such as an attached route or a branch route, may be mistakenly received as a received signal from a regular route. In digital wireless communication systems, sub data signals for monitoring and controlling the radio section are usually multiplexed with the main data signal and transmitted. Therefore, a route identification code is included in the sub data signal, and this code is transmitted at the receiving end of the line. A route identification method has been used in which a route identification code is detected to confirm that a received data signal is a data signal transmitted through a regular route.

By the way, there is a forward error correction method in which a data signal to be transmitted is error-corrected encoded, sent, and then error-corrected and decoded on the receiving side.
When a block code is used as an error correction code, the bit at a specific position in each code word is inverted and sent, and word synchronization is performed on the receiving side based on the position of the inverted bit. A word synchronization method is known. In this word synchronization method, error correction decoding is performed on the premise that bits at specific positions in each code word are inverted and transmitted. ) Since a bit error always occurs in each code word, the performance of preventing false synchronization is high.

[Problem to be solved by the invention]

The conventional route identification method described above has the disadvantage that the transmission efficiency of the line decreases because it is necessary to multiplex the route identification code with the main data signal and transmit it.

An object of the present invention is to provide an FFC that uses the above-mentioned word synchronization method.
An object of the present invention is to provide a route identification method that can identify a route without transmitting special bits such as a route identification code in a digital wireless communication system.

[Means to solve the problem]

The route identification method of the present invention includes an encoder that encodes a data signal to be transmitted into an error correction code, and a specific bit inverter that inverts bits at a predetermined position of an error correction code word input from the encoder on the transmitting side. In a digital wireless communication system, the receiving side is equipped with decoding means for error correction decoding in word synchronization based on the predetermined position of the inverted bit, in which the predetermined position is different for each route. is configured to perform route identification.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The embodiment shown in FIG. 1 includes an FEC encoder 1, a specific bit inverter 2, and a modulator 3 on the transmitting side, a demodulator 42, a divider circuit 5. Bit pattern correction circuit 6, synchronization detection circuit 7. F
It is configured to include an EC decoder 8 and an exclusive OR circuit 9 on the receiving side.

The FEC encoder 1 encodes a data signal to be transmitted into a block code using error correction coding. The specific bit inverter 2 is FEC
Bits at specific positions of each code word input from the encoder 4 are inverted and output to the modulator 3. The specific position at which the bits are inverted is set differently for each route, corresponding to the route identification code indicating each route in the digital wireless communication system. The modulator 3 modulates the input data signal and sends the modulated signal to a wireless circuit (not shown).

The demodulator 4 demodulates the modulated signal transmitted via the wireless line and outputs a data signal. This data signal is the same data signal as the data signal input to the modulator 3, if transmission code errors are ignored. It divides each block by the generator polynomial and outputs the remainder. If the timing of blocking is correctly word-synchronized and each block matches the code word, and there is no inversion of specific bits by the specific bit inverter 2, the output of the division circuit 5 is a syndrome, and a transmission code error is detected. When there is no one, it becomes “0”. but,
Because the specific bit is inverted by the specific bit inverter 2, when the word synchronization is correct and there is no transmission code error,
The output of the division circuit 5 does not become "0".

The bit pattern correction circuit 6 corrects and outputs the bit pattern output from the division circuit 5 so as to restore the change that the syndrome undergoes due to the inversion of a specific bit by the specific bit inverter 2. The logical operation for this modification is uniquely determined by the route identification code input to the bit pattern modification circuit 6, or in other words, the specific position in the specific bit inverter 2 at which the bit is to be inverted. If the word synchronization of the divider circuit 5 is correct, the output of the bit pattern correction circuit 6 is a syndrome.

The synchronization detection circuit 7 receives “
When the probability of occurrence of a value other than 0'' is greater than a certain threshold, it is determined that word synchronization is incorrect and the blocking timing of the divider circuit 5 is corrected. When it is determined that word synchronization is achieved, the input from the bit pattern correction circuit 6 is corrected. It is output as a syndrome to the FEC decoder 8, and becomes "1" only in the time slot of the decoded bit corresponding to the inverted bit in the code word, and becomes "1" only in the time slot of the decoded bit corresponding to the other bits. Then, a signal of "0" is output to the exclusive OR circuit 9.

The FEC decoder 8 corrects transmission code errors by decoding the data signal from the demodulator 4 using the syndrome input from the synchronization detection circuit 7.

In the time slot of the inverted bit in the data signal output by the FEC decoder 8, one input of the exclusive OR circuit 9 is "1", so the inverted bit is exclusive ORed. The data signal which is inverted again by the circuit 9 and outputted by the exclusive OR circuit 9 is a transmitted data signal in which the inversion of the specific bit in which the transmission code error has been corrected has been undone.

If the demodulator 4 erroneously outputs a data signal from another route, the bit pattern of this data signal will change because the specific bits corresponding to the route identification code input to the bit pattern correction circuit 6 have not been inverted on the transmitting side. The output of the correction circuit 6 will never be the correct syndrome, and therefore the synchronization detection circuit 7 will never judge that word synchronization has been achieved, so the data signal from another route cannot be replaced with the data signal transmitted through the regular route. There is no mistaking that there is.

Assume that data signals are transmitted in N1 columns in parallel, and a maximum of N bits in each column in one code word are inverted, and a minimum of 1 bit in one code word is inverted N h for word synchronization, then 2 - One route identification is possible.

〔Effect of the invention〕

As explained above, the present invention differs for each route by changing the position of the bit to be inverted for word synchronization.
Route identification can be performed without transmitting special bits such as a route identification code, which has the effect of improving line transmission efficiency.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1... FEC encoder, 2... Specific bit inverter, 3... Modulator, 4... Demodulator, 5... Division circuit, 6...Bit pattern correction circuit, 7...Synchronization detection circuit, 8...
...FEC decoder, 9...Exclusive OR circuit. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] The transmission side is equipped with an encoder that encodes the data signal to be transmitted with error correction coding, and a specific bit inverter that inverts the bits at predetermined positions of the error correction code word inputted from the encoder. A digital communication system in which a receiving side is equipped with decoding means for performing error correction decoding in word synchronization based on a predetermined position, characterized in that route identification is performed by making the predetermined position different for each route. route identification method.