JPH1056401A - Transmission/reception synchronization circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission/reception synchronization circuit in which a synchronization phase search time is reduced even in the case that synchronization is acquired matching a clock having a period longer than a period of a spread code or over. SOLUTION: A reception section 210 of a mobile station P200 is provided with a radio demodulation section 211 connecting to an antenna 310, a spread demodulation section 212, an error correction decoding section 213, a frame recovery section 214 and a transmission clock generator 215, and a transmission section 220 of the mobile station P200 is provided with a frame generating section 221, an error correction coding section 222, a spread modulation section 223 and a radio modulation section 224. A base station B sends a data frame having a period longer than a period of a spread code, the reception section 210 of the mobile station P200 extracts a signal of the data frame sent from the base station B100 and matches a synchronization position of the data frame of the transmission section 220 of the mobile station P200 with the position of the extracted data frame of the base station B100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transmission / reception synchronization circuit of a transmission / reception system of mobile communication, and more particularly to a transmission / reception system of mobile communication using a code division multiple access (CDMA) communication system. The present invention relates to a transmission / reception synchronization circuit.

[0002]

2. Description of the Related Art In recent years, research and development on a CDMA communication system has been actively conducted as one of techniques for improving the frequency use efficiency in mobile communication.

[0003] In this CDMA, an interference signal from a transmitting station other than a desired signal multiplexed in a spreading / despreading process is treated in the same manner as thermal noise, so that it is proportional to the processing gain. The same number of transmitting stations can use the same frequency band at the same time. In CDMΑ, for example, direct diffusion (DS: Direct Seq
uence), transmitting stations such as users using the same frequency are separated by pseudo orthogonal codes.

Examples of a transmission / reception synchronization circuit using the CDMA communication system include, for example, “Applied technology of spread spectrum communication system, 1992, supervision of Yukiji Yamauchi”, p23-p32, p53.
-P73.

A conventional synchronization method represented by the above document will be described.

Generally, the receiving side knows the carrier frequency Fc, the data bit rate, the chip rate of the spreading code, and the 0 and 1 patterns of the spreading code, and may not know the phase of the spreading code. Many.

Therefore, it is necessary to match the phases (timings) of the spread codes on the transmitting side and the receiving side before performing communication. Matching the phases of the spread codes of the transmission system and the reception system in this way is called "taking synchronization", and searching for a phase in which this synchronization can be achieved is called "searching". The time until completion is called "search time".

In the SS (Spread Spectrum) system or CDMA, the phase of the spreading code is shifted between the transmitting side and the receiving side if nothing is done. Therefore,
In order to achieve synchronization, the phase of the spreading code on the receiving side (timing for obtaining the correlation with the spreading code) is slid in order to obtain the correlation, and when the correlation value exceeds a certain threshold value (the peak of the correlation value is detected). At that point).

[0009]

However, in such a conventional method for synchronizing transmission and reception, when a search is performed using the sliding correlation as described above, the spreading code on the transmitting side and the spreading code on the receiving side are used. The search time is required for the phase difference of the above, and the search time for almost one cycle of the spread code is required at the maximum phase difference. When the period of the spread code is short, the search time is short in the above-described conventional method, but when the period of the spread code is long, the search time becomes very long.

Therefore, in the conventional method, it is difficult to achieve synchronization in a short time when using a spreading code having a long cycle.

If the one-way communication is already synchronized in the two-way communication, the time for the synchronization can be reduced. However, in the conventional method, an appropriate method has not been adopted. However, it was not possible to shorten the time for searching for the synchronization phase.

An object of the present invention is to provide a transmission / reception synchronization circuit capable of shortening the time required to search for a synchronization phase even when synchronization is performed in synchronization with a clock having a longer cycle than the cycle of a spreading code. I do.

[0013]

A transmission / reception synchronization circuit according to the present invention is a transmission / reception synchronization circuit of a mobile station capable of two-way communication with a base station. Means are provided for synchronizing the code and the spread code transmitted from the transmission section of the mobile station.

Further, the transmission / reception synchronization circuit according to the present invention is a transmission / reception synchronization circuit of a transmission unit and a reception unit of a mobile station capable of two-way communication with a base station, wherein the base station has a period larger than the period of the spreading code. The receiving section of the mobile station is configured to be capable of transmitting a data frame, and the extracting section extracts the signal of the data frame sent from the base station, and the synchronous position of the data frame of the transmitting section of the mobile station is extracted by the extracting section. Means for adjusting the position to the position of the data frame of the base station.

The data frame may be data having a period that is an integral multiple of the period of the spreading code. The two-way communication uses spread spectrum and code division multiple access (CDM).
Mobile communication using A) may be used.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A transmission / reception synchronizing circuit according to the present invention comprises:
The present invention can be applied to a transmission / reception synchronization circuit used in a mobile communication system using the CDMA communication system.

First, the basic concept of the transmission / reception synchronization circuit according to the present invention will be described.

In order to realize a telephone call service in mobile communication (particularly, CDMA communication), it is essential that two-way communication be possible.

In the transmission / reception synchronization circuit according to the present invention, taking advantage of the fact that the two-way communication is possible, the following means are used to reduce the synchronization time. For convenience, a device that transmits a signal to be synchronized in a short time is a mobile station P, and a device that receives a signal and is synchronized in a short time is a base station B. Further, it is assumed that the base station B sends a data frame having a cycle larger than the cycle of the spreading code (an integer multiple of the cycle of the spreading code).

The mobile station P has a function of extracting a synchronization signal from the signal transmitted from the base station B and adjusting the synchronization position of the data frame of the transmission section of the mobile station to the position of the data frame of the base station. .

By providing the above function, utilizing the fact that the above two-way communication is possible, even when transmitting frame data having a period longer than the period of the spread code (an integer multiple of the period of the spread code), , The time for synchronization can be reduced.

That is, first, a signal S1 is transmitted from the base station B to the mobile station P via a transmission / reception radio frequency (RF). In the mobile station P, the receiving unit receives the signal S1 'via RF.
The receiving unit synchronizes by sequentially sliding the phase of the spread code by the above-described conventional method.

When synchronization is established, the receiving section of the mobile station P generates a clock CLK1 in accordance with the cycle of the spreading code and
Send to U. The CPU that has received CLK1 generates a clock CLK2 having a longer cycle than CLK1 from CLK1 and the data demodulation signal.
(N times the clock of CLK1). Clock C
The clock generator receiving LK2 generates CLK1 and CLK2.
2 generates a clock CLK3 on the transmission side, and sends a signal R1 for resetting the phase of the spread code of the transmission unit of the mobile station P to the transmission unit. The transmitting unit that has received the signal R1 spreads and transmits the frame data at the same timing as the receiving unit.

By performing the above operation, the mobile station P
The phase difference between the spreading code of the transmitting system and the spreading code of the receiving system of the base station B is only the propagation delay between the base station Β and the mobile station P. Therefore, on the receiving side of the base station B, by starting the search in synchronization with the clock of the transmitting side of the base station B, it becomes possible to establish synchronization in a very short time within one cycle of the spreading code.

FIG. 1 is a block diagram showing a configuration of a transmitting / receiving system for mobile communication according to an embodiment of the present invention based on the above basic concept. This is an example applied to a communication system using CDMA.

In FIG. 1, 100 denotes a base station capable of transmitting a data frame having a period larger than the period of the spreading code (an integer multiple of the period of the spreading code), and 200 transmits a signal to be synchronized in a short time. The device is connected to mobile station P, 300, 31
0 is an antenna of the base station B and the mobile station P. The base station B and the mobile station P each include a transmitting side and a receiving side as described below.

The transmission section 110 of the base station B includes a frame generation section 111, an error correction coding section 112, and a spread modulation section 113.
And a wireless modulation unit 114.
Is connected to the antenna 300. The receiving unit 120 of the base station B includes a wireless demodulating unit (wireless receiving unit) 121, a spread demodulating unit 122, an error correction decoding unit 123, and a frame reproducing unit 124.

The error correction coding unit 112 calculates a CRC (cyclic redundancy check code) coefficient for error detection, performs convolution coding, and performs interleave conversion.

On the other hand, the receiving section 210 of the mobile station P includes a radio demodulating section (radio receiving section) 21 connected to the antenna 310.
1, a spread demodulation unit 212, an error correction decoding unit 213, a frame reproduction unit 214, and a transmission clock generator 215.

The transmitting section 220 of the mobile station P comprises a frame generating section 221, an error correction coding section 222, a spread modulation section 223 and a radio modulation section 224.

As described above, in the mobile station P, a synchronization signal is extracted from the signal transmitted from the base station B, and the synchronization position of the data frame of the transmission unit of the mobile station is adjusted to the position of the data frame of the base station. As described above, this function is performed by the spread demodulation unit 212, the frame reproduction unit 214, and the transmission clock generator 215 in the reception unit 210, and is realized by the frame generation unit 221 and the spread modulation unit 223 in the transmission unit 220.

FIG. 2 is a diagram showing a detailed configuration of the spread demodulation section 122 of the reception section 120 of the base station B.

In FIG. 2, a spreading demodulation section 122 includes a spreading code generator 401, a multiplier 402, a cumulative adder 403,
It comprises a normalizer 404 and a synchronization determiner 405.

The spreading code generator 401 generates a spreading code PS # synchronized with the system clock BSC of the base station #.

Here, the spreading code PS of the transmitting section of the mobile station Ρ
The difference between the phase of the PN and the phase of the spreading code PSP # of the base station Β is substantially equal to the difference of the propagation delay between the base station Β and the mobile station P by performing the above series of operations.

The operation of the transmission / reception system for mobile communication using CDMA configured as described above will be described below.

It is assumed that the cycle of the spreading code used in base station B and mobile station Τ is Τ1 (20 [ms]), and the unit of a frame to be communicated is Τ2 (80 [ms]). Spreading code period {1 (20 [ms]) and one period of data frame}
2 (80 [ms]) is shown in FIG.

Operation of transmitting section 110 of base station B It is assumed that base station B is operating with system clock #SC.

First, in the frame generation unit 111, $ 2 (8
0 [ms]), one bit of data bit Sbit indicating the head of the frame is inserted at the head of the frame.

The frame generator 111 outputs the # 2 frame FBS1 to the error correction encoder 112.
The error correction encoding unit 112 performs error correction encoding of the frame FBS1, generates a frame FBS2, and outputs the frame FBS2 to the spread modulation unit 113.

In the spreading modulator 113, the frame FBS2
Is synchronized with the system clock BSC and the spreading code BSPN
To generate spread data D1. The spread data D1 is converted into a radio wave F1 by the antenna 300 via the radio modulation unit 114 and transmitted to the mobile station P.

Operation of receiving section 210 of mobile station P In mobile station P, radio wave F1 'received from antenna 310
Is modulated into a baseband signal D2 by the radio demodulation unit 211,
The signal is sent to the spread demodulation unit 212. Spreading demodulation section 212 demodulates data D2 using spreading code BSPN and demodulates data D3.
Generate

Then, a clock CLK1 (20 [ms]) is generated in accordance with the cycle of the spreading code (PN) used for demodulation, and is output to the transmission clock generator 215.

In the error correction decoding section 213, the radio demodulation section 2
The data D3 demodulated in step 11 is subjected to error correction decoding to generate decoded data D4, and the decoded data D4 is output to the frame reproducing unit 214.

In the frame reproducing section 214, the decoded data D
4 from the Sbit and CLK1 included in
A clock C having a double period (here, 80 [ms])
LK2 is generated and output to the transmission clock generator 215.

The transmission clock generator 215 receives the clock CLK 2 output from the frame reproducing unit 214 and the clock 1 from the spread demodulation unit 212 and receives the clock CLK
2 as a trigger, the clock CL of the wireless demodulation unit 211
A clock CLK3 of T2 [ms] synchronized with K1 is generated and output to the transmitting side (transmitting section 220).

Operation of transmitting section 220 of mobile station P In transmitting section 220 of mobile station P having received CLK3, Τ2 [ms] generated by frame generating section 221 of transmitting section 220.
Is output to the error correction encoding unit 222.

In the error correction encoding unit 222, the frame F
Performs error correction coding on PS1 and performs frame FPS
2 is generated and output to the spread modulator 223.

The spread modulator 223 outputs the clock CLK3
The frame FPS2 in synchronization with the error correction encoding unit 222
, And the spreading code B
Spread modulation is performed using another spreading code ΡSPN synchronized with the SPN to generate spread data E1.

The generated spread data # 1 is converted to radio wave F2 by antenna 310 via radio modulation section 224.
Transmitted to base station B.

With the above operation, the timing of the frame data on the receiving side and the transmitting side of the mobile station P are synchronized with the timing of the phase of the spreading code.

Operation of Receiving Unit 120 of Base Station B At base station Β, radio wave F2 ′ received from antenna 300
Is modulated into a baseband signal E2 by the radio demodulation unit 121,
The signal is sent to the spread demodulation unit 122. The spread demodulation unit 122 performs a search using the data E2 spread code PSPN.

The detailed operation will be described below.

FIG. 2 is a diagram showing a detailed configuration of the spread demodulation unit 122. As described above, the spread demodulation unit 122 includes a spread code generator 401, a multiplier 402, and a cumulative adder 40.
3, a normalizer 404 and a synchronization determiner 405. In this case, the spreading code generator 401
Spreading code synchronized with the system clock BSC
Occurs.

Here, the spreading code PS of the transmitting unit of the mobile station Ρ
The difference between the phase of the PN and the phase of the spreading code PSP # of the base station Β is substantially equal to the difference of the propagation delay between the base station Β and the mobile station P by performing the above-described series of operations.

The received data # 2 and spreading code PSPN are output to multiplier 402. The multiplier 402 multiplies the spreading code PSPN by the data E2 and outputs the multiplication result # 3 to the accumulator 403.

The accumulative adder 403 accumulatively adds E3 by a processing gain to obtain an accumulative added value E4, which is output to the normalizer 404.

The normalizer 404 normalizes the accumulated value E4 with the process gain to obtain a correlation value CP1, and outputs the correlation value CP1 to the synchronization determiner 405.

When the correlation value CP1 is equal to or smaller than the “threshold” inside the synchronization determiner 405,
A control signal C62 is output to the spreading code generator 401.

Spread code generator 4 receiving control signal C62
01 performs an operation of advancing (or delaying) the phase of the spreading code PSP # to generate a spreading code PSPN 'having a different phase. Next, using the new spreading code PSPN ', a correlation value CP1' is obtained in the same manner as described above,
Is used to determine synchronization.

The above operation is repeated, and when the correlation value CP1 'becomes equal to or more than the "threshold value" of the synchronization determiner, it is regarded that transmission and reception have been synchronized.

Here, the spreading code PSPN of the transmitting section 220 of the mobile station P and the spreading code PSPN of the receiving section 120 of the base station B are used.
Since the phase difference from the PN is substantially equal to the propagation delay as described above, the number of times that the phase of the spreading code of the spreading code generator 401 is changed can be reduced.

Therefore, the time until synchronization is achieved can be reduced.

FIG. 3 shows a conceptual diagram of the above series of synchronous operations.

As can be seen from FIG. 3, the synchronization time (search time in FIG. 3) of the receiving unit 120 of the base station B is shorter than the synchronization time (search time) of the mobile station P. .

As described above, in the transmission / reception synchronizing circuit according to the present embodiment, the receiving section 210 of the mobile station P includes the radio demodulation section 211 and the spread demodulation section 21 connected to the antenna 310.
2, the error correction decoding unit 213, the frame reproduction unit 214, and the transmission clock generator 215, and the transmission unit 220 of the mobile station P includes the frame generation unit 221, the error correction encoding unit 2
22, a spreading modulator 223 and a radio modulator 224,
The base station B sends a data frame (period T2) having a period longer than the period T1 of the spreading code, and the mobile station P
The receiving unit 210 extracts the signal of the data frame transmitted from the base station B, and adjusts the synchronization position of the data frame of the transmitting unit 220 of the mobile station P to the position of the extracted data frame of the base station B. Therefore, by synchronizing the spreading code of the receiving unit 210 of the mobile station P and the spreading code of the transmitting unit 220, the spreading code of the transmitting system of the mobile station P and the spreading code of the receiving system of the base station B are synchronized. The phase difference can be reduced, and the receiving side of the base station Β can synchronize in a short time. This is especially useful when synchronization needs to be fast.

Therefore, by applying the transmission / reception synchronization circuit having such features to a base station reception system or a mobile station reception system, the transmission / reception performance of the system can be improved.

The transmission / reception synchronization circuit according to the above-described embodiment can be applied to a transmission / reception synchronization circuit on the receiving side of mobile communication using code division multiple access as described above, but of course is not limited to this. Of course, it is needless to say that the present invention can be applied to all devices (for example, a base station receiving system and a mobile station receiving system) as long as the communication system performs mobile communication.

Further, it is needless to say that the configuration of the mobile station, the circuit constituting the correlator and the like of the spread demodulation unit, the type and number of PN generators and the connection method are not limited to the above-described embodiment. .

[0070]

According to the transmission / reception synchronization circuit of the present invention, in the transmission / reception synchronization circuit of the mobile station capable of bidirectional communication with the base station, the spread code received by the reception section of the mobile station and the mobile station Since means for synchronizing the spread codes transmitted from the transmitting unit is provided, the time required to search for the phase of synchronization can be reduced.

In the transmission / reception synchronization circuit according to the present invention,
In a transmission / reception synchronization circuit of a transmission unit and a reception unit of a mobile station capable of bidirectional communication with a base station, the base station is configured to be able to send a data frame having a period larger than the period of the spreading code, and the reception unit of the mobile station Extracting means for extracting a signal of the data frame transmitted from the base station, and means for adjusting the synchronization position of the data frame of the transmitting section of the mobile station to the position of the data frame of the base station extracted by the extracting means. With this configuration, it is possible to reduce the phase difference between the spreading code of the transmitting system of the mobile station and the spreading code of the receiving system of the base station, and the receiving side of the base station must synchronize in a short time. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a transmission / reception synchronization circuit according to an embodiment to which the present invention is applied.

FIG. 2 is a diagram illustrating a configuration of a spread demodulation unit of a reception unit of a base station.

FIG. 3 is a diagram for explaining a synchronization mechanism of the transmission / reception synchronization circuit.

[Explanation of symbols]

100 base station B, 110 transmitting section of base station B, 11
1,221 frame generator, 112,222 error correction encoder, 113 spreading modulator, 114,224 radio modulator, 120 base station B receiver, 121 radio demodulator, 122,212 spreading demodulator, 123, 213
Error correction decoder, 124, 214 frame reproducer, 2
00 Mobile station P, 210 Receiver of mobile station P, 211
Radio demodulation unit, 215 transmission clock generator, 220 Transmission unit of mobile station P, 223 Spread modulation unit, 300, 310
Antenna, 401 spreading code generator, 402 multiplier, 403 cumulative adder, 404 normalizer, 405
Synchronous judgment device

Claims (4)

[Claims] 1. A transmission / reception synchronization circuit of a transmission unit and a reception unit of a mobile station capable of two-way communication with a base station, wherein the spread code received by the reception unit of the mobile station is transmitted from the transmission unit of the mobile station. A transmission / reception synchronization circuit comprising means for synchronizing a spread code. 2. A transmission / reception synchronization circuit of a transmission unit and a reception unit of a mobile station capable of two-way communication with a base station, wherein the base station is configured to be able to transmit a data frame having a period larger than a period of a spreading code, A receiving unit of the mobile station, the extracting unit extracting a signal of a data frame transmitted from the base station; and a synchronization position of a data frame of a transmitting unit of the mobile station, the base unit extracted by the extracting unit. Means for adjusting to the position of the data frame of the station. 3. The transmission / reception synchronization circuit according to claim 2, wherein the data frame is data having a cycle that is an integral multiple of the cycle of the spread code. 4. The two-way communication includes spread spectrum and code division multiple access (CDMA).
3. The transmission / reception synchronization circuit according to claim 1, wherein the transmission / reception synchronization circuit is a mobile communication using the “le Access”.