JPH07307718A - Mobile radio communication system - Google Patents

Abstract

PURPOSE:To reduce odd mutual correlations, to establish a symbol synchronization with a simple constitution and to simplify the constitution of the reception part of a base station. CONSTITUTION:A spread spectrum multiple access communication is performed by using the spreading code of polyphase orthogonal series between a base station 1 and plural moving machines 2. By setting the information channel corresponding to a common channel 5 for synchronization and each moving machine to the outgoing line from the base station to the moving machine and delaying the signal of each information channel, a chip deviation is generated between the transmission symbol timing of this information channel and the symbol timing of the common channel for synchronization and the delay amount 8 in each information channel is set so that the size of the chip deviation in each information channel at the time may be evenly distributed within the range of a chip deviation width. By making the signal of each information channel modulated by the spreading code of the polyphase orthogonal series have the chip deviation, odd mutual correlations are reduced. The moving machines are capable of detecting its own correlation without receiving the interferences between other stations. The base station is capable of performing correlation detection of the signal of each moving machine without odd mutual correlations because the signals transmitted from each moving machine mutually have chip deviations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system such as a digital mobile phone or a mobile phone, and more particularly, it is configured to reduce mutual interference in spread spectrum communication using spread codes of polyphase orthogonal sequences. .

[0002]

2. Description of the Related Art In spread spectrum communication, the spectrum of an information signal is spread and transmitted in a band sufficiently wider than the original information bandwidth.

As described in the paper "Modulation and Demodulation of Spread Spectrum" (Tachikawa: Electronic Information Communication Society 93 Spring Conference <Basic Boundary Group> Spread Spectrum in Consumer Communication and Personal Communication), a plurality of binary codes are used. In direct spread spectrum spread communication, in which an information signal is multiplied by an arrayed binary spread code as it is (data modulation) and transmitted, one symbol (generally, one bit of an information signal corresponds to one bit is transmitted on the transmitting side. For n), the information signal is modulated by sequentially multiplying n (n chips) binary codes forming the spread sequence code and repeating this cyclically for each bit of the information signal. A code such as an M sequence or a Gold sequence is used as the binary sequence spreading code. On the other hand, on the receiving side, correlation detection (despreading) is performed using the same code as the spreading sequence code used at the time of transmission, so that there is one peak for one symbol as shown in FIG. 7A. Detect the autocorrelation waveform.

On the other hand, the paper “Multi-phase periodic sequences without cross-correlation and its application to asynchronous SSMA communication” (Suehiro,
Hatori: IEICE Transactions '85 / 10, Vo
l. J68-A, N0.10, pp. 1087-109
3) has no cross-correlation (that is, of orthogonal sequences),
A spreading code sequence of a complex number sequence (that is, a polyphase sequence) has been proposed. Unlike a binary sequence, a polyphase sequence has a complex number in each chip that constitutes a spread sequence code, and this complex number is located on the circumference of the complex plane (IQ plane) shown in FIG. The absolute value is constant.

In this polyphase orthogonal sequence, a plurality of pulses appear for one symbol in the autocorrelation waveform when despreading using the same code sequence. FIG. 7B shows an autocorrelation waveform in which a peak appears every three chips.

FIG. 9 shows a method of spreading and despreading transmission data by this polyphase orthogonal sequence. On the transmission side (a), the transmission data is multiplied by the I component (PNi) 40 and the Q component (PNq) 41 of the assigned polyphase orthogonal spreading sequence code to obtain the I and Q components of the transmission signal. obtain.

On the other hand, on the receiving side (b), the I component of the received signal is multiplied by the spread code PNi42 by the correlation circuit 43 and by the spread code PNq44 by the correlation circuit 45 to obtain II and I.
Q and Q are similarly calculated from the Q component, II and QQ, −IQ and QI are added by adders 46 and 47, respectively, and the addition result is obtained by a multiplier 48. Demodulate by finding the sum of squares of.

In the spread spectrum communication using the spread code of this polyphase orthogonal sequence, since the cross-correlation is small, the number of stations in the multiple access communication can be increased.

In a mobile communication system which performs spread spectrum multiple access communication (SSMA) using spread codes of polyphase orthogonal sequences, as shown in FIG. 10, a plurality of mobile stations are transmitted from a transmitter 52 of a base station 50 through a downlink. The data is sent to the receiving unit 53 of the mobile device 51, and the data is transmitted from the transmitting unit 64 of each mobile device 51 to the receiving unit 65 of the base station 50 through the uplink.

The transmitting section 52 of the conventional base station 50 includes a synchronizing data generating circuit 54 for generating synchronizing data and a spreading circuit for spreading the synchronizing data (data modulation) using a spreading sequence code for the synchronizing channel. 55 and a spreading circuit 56 that spreads the transmission data of each user using the assigned spreading sequence code.
And a combining circuit 57 for combining the spread signals of each channel
And a radio unit 58 for converting transmission data into a radio frequency signal for transmission, and the receiving unit 53 of the mobile device 51 has a radio unit 59 for receiving a radio frequency signal and a correlation detection of a synchronization signal. A despreading circuit 60 for carrying out the above, a synchronizing circuit 61 for obtaining symbol synchronization from the output of the despreading circuit 60, a despreading circuit 62 for detecting the correlation of the user i channel signal of the mobile device 51 based on the synchronization, and a received data And a demodulation circuit 63 for demodulating

Further, the transmitter 64 of the mobile device 51 is provided with a spreading circuit 66 for spreading the transmission data using the assigned spreading sequence code, and a radio unit 67, and the receiver 65 of the base station 50 has an uplink. Radio unit 68 that receives signals sent through the line
A despreading circuit 69 for detecting the correlation between the channel signals of the users 1 to n, a synchronizing circuit 70 for obtaining synchronization by using a synchronizing signal or the like set in some symbols of the signals of the respective channels, Demodulation circuit 71 for demodulating received data of each channel
It has and.

In the transmission unit 52 of the base station 50, the transmission data of each channel is spread (data modulated) by the spreading circuit 56 using each assigned spreading sequence code, and the synchronization data generating circuit 54 is also used. The synchronization data generated in 1 is spread in the spreading circuit 55 using the spreading sequence code forming the common channel for synchronization. The synchronization data is combined with the spread signal of each channel in the combining circuit 57 and transmitted through the wireless unit 58.

FIG. 11A shows the symbol timing of the signal of each channel transmitted through the downlink at this time, and the symbols are transmitted at the same timing in each channel. When the number of symbols (the number of bits) having a certain length on the time axis is set as one frame and is transmitted in frame units, the symbol No. of each channel is set. Each frame is transmitted so that

On the other hand, in the receiving section 53 of the mobile unit 51, the despreading circuit 60 performs correlation detection of the received signal using the spreading sequence code used for spreading the synchronizing data, and the synchronizing circuit 61
Extract symbol synchronization from its output. The despreading circuit 62 and the demodulation circuit 63 perform correlation detection using the spreading sequence code of channel i in synchronization with the synchronization and reproduce the received data.

In the case of a communication device in which the common channel for synchronization is not set, the receiving unit 53 of the mobile device 51 uses the synchronization signal set in some symbols in each channel signal to perform synchronization. To earn.

On the other hand, in the uplink (the line from the mobile station 51 to the base station 50), the transmission data is spread in the spreading circuit 66 of the transmission section 64 of the mobile station 51 using the assigned spreading sequence code, It is transmitted through the wireless unit 67. At this time,
The transmission timing of each mobile device is asynchronous, and FIG.
As shown in (b), the symbol timing and symbol No. of each user (channel). The positional relationship of is different. Therefore, in the receiving unit 65 of the base station 50, the wireless unit 68
The despreading circuit 69 detects the correlation of the received signal from the user, and the synchronization circuit 70 is used to acquire the synchronization, and the demodulation circuit 71 demodulates the received data based on the synchronization.

[0017]

However, in conventional mobile communication using a polyphase orthogonal sequence as a spreading code, when a mobile station on the downlink receiving side despreads a received signal,
There is a problem that performance deteriorates due to interference between other stations.

In this polyphase orthogonal sequence, since the code sequences are orthogonal, the cross-correlation should be 0 when despreading with non-identical code sequences, but the cross-correlation is
There are even cross correlation and odd cross correlation, and when this polyphase orthogonal sequence is used as a spreading code, the even cross correlation becomes 0,
The odd cross correlation does not become zero.

The even cross-correlation is a correlation that occurs when continuous data (symbols) are +1 and +1 when they are spread with a spreading code sequence and despread with another spreading code sequence. is there. The odd cross-correlation is a correlation that occurs when continuous data is +1 and −1 and is spread by a spreading code sequence and despread by another spreading code sequence. In order to reduce the interference between other stations, it is necessary to keep the cross-correlation between them low.
However, it is generally difficult to analyze the odd cross-correlation and it is difficult to reduce it. Therefore, although insufficient, in SSMA, only the even cross-correlation is analyzed.
The reduction is aimed at. Even in SSMA that uses a polyphase orthogonal sequence as a spreading code, since there is an odd cross-correlation, it is not possible to completely eliminate inter-station interference.

Further, in spread spectrum communication using a polyphase orthogonal sequence, since the autocorrelation waveform is not one symbol / one peak as in binary codes such as M sequences, a plurality of peaks exist for one symbol. There is a problem in that the structure of the synchronization circuit for symbol synchronization becomes complicated.

Further, in the conventional mobile communication system, since the transmission timing of each mobile unit in the uplink is asynchronous, it is necessary to provide a synchronizing circuit for each user in the receiving unit on the base station side, which requires a large hardware scale. There is a problem that you have to do it.

The present invention solves these conventional problems. In SSMA using a polyphase orthogonal sequence, it is possible to reduce the odd cross-correlation and establish symbol synchronization with a simple structure. Another object of the present invention is to provide a mobile communication system that can simplify the configuration of the receiving unit of the base station.

[0023]

Therefore, according to the present invention, in a mobile communication system in which spread spectrum multiple access communication is performed between a base station and a plurality of mobile devices using a spread code of a polyphase orthogonal sequence, a base station A common channel for synchronization and an information channel corresponding to each mobile station are set on the downlink from the mobile station to the mobile station, and the transmission symbol timing of this information channel and the symbol of the common channel for synchronization are delayed by delaying the signal of each information channel. The chip shift is generated between the timing and the delay amount of each information channel so that the magnitude of the chip shift in each information channel at that time is uniformly distributed within the range of the chip shift setting width. .

Further, each mobile station sets a window capable of capturing the symbol timing of the own information channel based on the detected symbol timing of the common channel for synchronization and the information on the chip shift in the own information channel. The correlation detection is performed within the range.

In addition, on the downlink from the base station to the mobile unit,
A control channel is provided to notify the magnitude of chip shift in each information channel.

Further, the mobile station transmits an uplink signal from the mobile station to the base station at a transmission symbol timing obtained by adding a chip shift to the symbol timing of the synchronization common channel, and the base station transmits information on the uplink. A window that can capture the symbol timing of the channel is set, and correlation detection is performed within the range of this window.

Further, the magnitude of the chip shift added to the uplink signal is set to be equal to the magnitude of the chip shift of the own information channel in the downlink.

Further, the reception output correlation-detected within the window range is configured to be combined by Rake reception.

[0029]

As described above, the odd cross-correlation is reduced by giving a chip shift to the signal of each information channel modulated by the spreading code of the polyphase orthogonal sequence. Therefore, the mobile device can detect the autocorrelation waveform without receiving interference from other stations, and the base station has a chip shift between the signals transmitted from the mobile devices, which causes an odd cross-correlation. It is possible to detect the correlation between the signals of the respective mobile devices without involving.

In the mobile device, the magnitude of the chip shift in the own information channel can be known in advance or through the control channel. The mobile device recognizes the symbol timing in the own information channel based on the magnitude of this chip shift and the symbol timing of the synchronization common channel obtained by the synchronization detection, and has a certain chip width in which this symbol timing can enter. A window is set, correlation detection is performed in the range of this window, and the information signal is reproduced.

The base station also considers the chip shift given to the information channel of each mobile device, the transmission delay of the uplink / downlink, the processing delay in each mobile device, etc. A window that can catch the transmission symbol timing is set, correlation detection is performed within the range of this window, and the signal transmitted from each mobile device is reproduced. In this way, the base station can roughly predict the transmission symbol timing from each mobile device, and therefore it is not necessary to provide a synchronization circuit for each information channel.

In addition, in the mobile station and the base station, the reception outputs correlated with each other in the window range are combined by the Rake reception, so that the path diversity effect can be obtained and the reception quality can be improved.

[0033]

EXAMPLES First, a new finding for reducing an odd cross-correlation, which was the origin of the present invention, will be described.

The inventor has found that SSM using polyphase orthogonal sequences
In A, unlike the case of using a binary code such as M series or Gold series, the odd cross-correlation is reduced by phase-shifting (chip-shifting) the spread signals of a plurality of channels modulated by the spread code series and combining them. I found what to do.

FIGS. 3 to 6 are diagrams showing this relationship. In FIG. 3, data of "+1, +1, +1, +1" is data-modulated by a polyphase orthogonal sequence a and the same sequence a is used. The measurement result of the autocorrelation value at the time of demodulation is shown. Also, FIG.
Is data modulation of data of "+1, -1, +1, -1" using another plurality (32 pieces) of polyphase orthogonal sequences b _{1 to} b _32, and for a signal obtained by adding them, Polyphase orthogonal sequence a
7 shows the measurement result of the odd cross-correlation value when demodulating using. In addition, at this time, each polyphase orthogonal sequence b _{1 to} b
₃₂ performs data modulation on each data at the same timing. That is, each polyphase orthogonal sequence b _{1 to} b ₃₂
Does not cause chip misalignment.

Further, in FIG. 5, the modulated signal in FIG. 3 and the modulated signal in FIG. 4 are added, and this is added to the polyphase orthogonal sequence a.
Shows the correlation value when demodulated using.

FIG. 5 corresponds to the reception status of the mobile station in SSMA. As is clear from the figure, the autocorrelation value cannot be clearly identified due to the interference due to the odd cross-correlation.

On the other hand, FIG. 6 shows "+1, -1, +1,-.
1 ”data is modulated with 32 multi-phase orthogonal sequences b _{1 to} b ₃₂ having a chip shift (that is, the timing of data modulation for each data is shifted by an integer multiple of the number of chips), and this modulation is performed. The signal and the modulation signal in FIG. 3 are added and the correlation value when demodulating this using the polyphase orthogonal sequence a is shown. At this time, the polyphase orthogonal sequences b _{1 to} b
The chip deviation in ₃₂ is within 10% of the number of chips in the polyphase orthogonal sequence, and the chip deviation of each polyphase orthogonal sequence is set to be uniformly distributed within this range. As is apparent from FIG. 6, polyphase orthogonal sequences b _{1 to} b ₃₂
The odd cross-correlation can be significantly reduced by adding the signals modulated by the method with the chip shift.

Now, the mobile communication system of the present invention, which realizes the reduction of odd cross-correlation by utilizing this phenomenon, is carried out between the base station 1 and a plurality of mobile units 2 shown in FIG.

In the base station 1, the transmitting unit 3 is provided with a synchronizing data generating circuit 5 for generating synchronizing data, a control data generating circuit 6 for transmitting information on chip deviation added to each channel, and synchronizing data. A spreading circuit 7 that spreads the data output from the generating circuit 5 and the control data generating circuit 6 and the data transmitted from each user, and a delay circuit 8 that adds a chip shift to the signal spread by each spreading circuit 7. A combining circuit 9 for combining the signals output from the delay circuits 8 and a radio section 10, and the receiving section 29 includes
A radio unit 30, a despreading circuit 31 for detecting correlation between channel signals for each user 1 to n, and a demodulation circuit 32 for reproducing received data of those channels are provided, and further, a synchronization data generation circuit 5 and control data are provided. A control circuit 4 for controlling each of the generation circuit 6, each delay circuit 8 and each despreading circuit 31 is provided.

The mobile unit 2 includes a receiving unit 11 and a radio unit 12
, A despreading circuit 14 for detecting the correlation of the synchronizing signal, and a synchronizing circuit 15 for extracting symbol synchronization from the output of the despreading circuit 14.
And a differential detection circuit 16 for decoding a differentially encoded frame synchronization word (unique word), and a unique word (UW) for extracting frame synchronization from the output of the differential detection circuit 16.
A detection circuit 17, a despreading circuit 18 for detecting correlation of control data, a demodulation circuit 19 for reproducing control data, a user i
It includes a despreading circuit 20 for detecting the correlation of the channel signal for use and a demodulation circuit 21 for reproducing the received data, and a transmitting section.
25, a spreading circuit 26 that spreads transmission data using the assigned spreading sequence code, a delay circuit 27 that adds a chip shift to the signal spread by the spreading circuit 26, and a radio unit 28.
And despreading circuits 14, 18, 20 and a delay circuit.
A control circuit 13 for controlling 27 is provided.

In this mobile communication device, transmission / reception of data on the downlink is performed as follows.

The control circuit 4 of the base station 1 commands the synchronization data generation circuit 5 to generate data, and the synchronization data generated by the synchronization data generation circuit 5 is assigned to the spreading circuit 7 by the spreading circuit 7. After being spread (data modulated) using the sequence code, it is input to the delay circuit 8. Delay circuit 8
Adds a chip shift of a size designated by the control circuit 4 to this signal.

Also, regarding the data of each channel transmitted from users 1 to n, the spreading circuit 7 spreads by using each assigned spreading sequence code, and the delay circuit 8 sets the size specified by the control circuit 4. Add a tip deviation.

The magnitude of the chip shift added to each channel is transmitted from the control circuit 4 to the control data generation circuit 6, and the control data generation circuit 6 generates data representing the chip shift of each channel. The generated data is also spread in the spreading circuit 7 and the chip shift is added in the delay circuit 8.

The spread signals of the respective channels output from the respective delay circuits 8 are combined by the combining circuit 9 and transmitted through the radio section 10.

FIG. 2A shows the symbol timing of the transmission signal of each channel in the downlink at this time. The magnitude of the chip shift is specified by the control circuit 4 so as to be uniformly distributed among the channels within a certain range (chip shift setting width). In FIG. 2A, the chip shift of the channel for transmitting the synchronization data (common channel) is set to 0, and the symbol positions of the channel for transmitting the control data (control channel) and each of the user channels 1 to n are
The figure shows a state in which the chips are displaced within the range of the chip deviation setting width.

As described above, by synthesizing the signals of the respective channels in the base station 1 in the state where there is a chip shift and transmitting the signals, each mobile unit 2 can obtain the autocorrelation without any odd cross-correlation.

Further, when the number of symbols (the number of bits) of a certain length on the time axis is set as one frame and is transmitted in frame units, the symbol No. of each channel is transmitted. Transmit each frame so that they are aligned with a chip shift. Further, in the case of performing frame-by-frame transmission, some symbols of the frame are used as unique words (UW) for frame synchronization, and the UW data is differentially generated from the synchronization data generation circuit 5 of the transmitter 3. Encode and output the value,
It is transmitted to each mobile device 2 through the common channel.

In the mobile unit 2 on the receiving side, the radio section of the receiving section 11
12 receives the signal, despreading circuit 14 performs correlation detection of the common channel signal in the received signal, and synchronization circuit 15 extracts symbol synchronization from its output and outputs it as a symbol clock. The differential detection circuit 16 decodes differentially encoded data, and the UW detection circuit 17 detects UW data from the output of the differential detection circuit 16 for frame synchronization and outputs a frame clock. To do.

The symbol clock and frame clock thus generated are also input to the control circuit 13. Using the symbol clock and the frame clock, the control circuit 13 has a certain width (chip width) such that the symbol timing (symbol change point) of the control channel is entered.
Then, the despreading circuit 18 is controlled to detect the correlation of the control channel signal within the range of the window. The output of the despreading circuit 18 is input to the demodulation circuit 19, and the demodulation circuit 19 outputs the control data.

This control data is also input to the control circuit 13, and the control circuit 13 identifies the magnitude of chip shift in its own information channel. Then, a window having a certain width (chip width) is set so that the symbol timing of one's own information channel can be entered, and for the despreading circuit 20,
Control is performed so that correlation detection of the own information channel signal is performed within that range. The output of the despreading circuit 20 is input to the demodulation circuit 21, which demodulates the received data of user i (channel i) and outputs it.

On the other hand, data transmission / reception in the uplink (the line from the mobile station to the base station) is performed as follows.

In the transmission unit 25 of the mobile unit 2 on the transmission side, the spreading circuit 26 spreads the transmission data using the assigned spreading sequence code, and the delay circuit 27, based on the designation from the control circuit 13, A chip shift corresponding to the chip shift between the symbol timing of the common channel signal in the downlink and the symbol timing of the own information channel is added to this spread signal. As a result, the symbol timing and frame timing of the own information channel received on the downlink are used as they are as the transmission symbol timing.

The spread signal added with the chip shift is transmitted from the radio unit 28 to the base station 1 through the uplink. Figure 2
(B) shows the symbol timing of each user (channel) at this time. In this way, since the symbol timing of each channel of the uplink has a chip shift, the receiving unit 29 of the base station 1 can detect the autocorrelation without causing an odd cross-correlation.

The addition of the chip shift in the delay circuit 27 is for causing the chip shift between the symbol timings of the respective channels in the uplink, so that the delay circuit 27 of each mobile unit is controlled by the control circuit 13. According to the designation, a chip shift of a random size may be added to the symbol timing of the common channel received on the downlink. Further, when the distance between the base station 1 and each mobile device 2 is greatly different, a chip delay occurs in the symbol timing of each channel received by the base station due to the transmission delay according to the distance, and therefore the delay circuit 27 is intentionally operated. Therefore, it is not necessary to add a tip shift.

In the receiving unit 29 of the base station 1 on the receiving side, the radio unit
30 receives the signal and sends it to the despreading circuit 31. At this time, the control circuit 4 determines the value of the chip shift added to each information channel in the downlink, the transmission delay of the uplink / downlink,
Also, the reception symbol timing for each user channel is obtained from the processing delay of each mobile device, and the reception window is set based on that. Then, each despreading circuit 31 is controlled to perform correlation detection of received data within the window range.
The output of the despreading circuit 31 is input to the demodulation circuit 19 and the demodulation circuit 19
Demodulates the transmission data and transmits it to each user.

As described above, in the mobile communication of the embodiment, each mobile unit 2 transmits the transmission data by adding a predetermined chip shift based on the common symbol timing of the downlink.
Therefore, the base station 1 can easily capture the symbol timing of each mobile device by using the reception window corresponding to each mobile device. Therefore, it is not necessary to provide a synchronization circuit for each channel.

In the spread spectrum communication, the characteristic of having high temporal resolution in reception is used to identify the signals transmitted from the same transmission source and received by following a plurality of paths (paths). The reception quality is improved by applying different weights to each other and performing a product-sum operation. This reception is called Rake reception, and Rak
The effect of receiving e is called the path diversity effect. The Rake reception can be utilized also in the mobile communication of the embodiment, and the demodulation circuits 19, 21 and 32 perform the path diversity by combining the reception signals by the Rake reception from the correlation value output in the set window width. It is possible to obtain an effect.

Further, in the system of the embodiment, the magnitude of the chip shift for each channel added by the delay circuit 8 of the transmitting unit 3 of the base station 1 is notified to each mobile device using the control channel. But this does not necessarily have to be the case. Especially, when the chip deviation setting width is small, the notification can be omitted. When the magnitude of the chip offset is not reported, the control circuit 13 of the mobile device performs the correlation detection with respect to the despreading circuit from the symbol clock of the common channel and the known chip offset setting width on the transmission side. Set the window width to allow it.

[0061]

As is apparent from the above description of the embodiments, in the mobile communication system of the present invention, a plurality of signals that are data-modulated by using a polyphase orthogonal sequence have a chip shift between them. Since it is set, the odd cross-correlation is reduced and the performance in demodulating the signal is improved.

Further, since each mobile unit can know the magnitude of the chip shift in its own channel through the information on the control channel, etc., it is possible to detect the symbol timing within the range of the window having a certain chip width. The synchronizing circuit can be simplified.

Further, since each mobile station sets the transmission symbol timing of the transmission data by adding a slight chip shift based on the received common channel symbol timing, the base station symbol of each channel is set. The timing can be detected within the range of a window having a certain chip width, and it is not necessary to provide a synchronizing circuit individually for each channel.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of an apparatus for implementing a mobile communication system of the present invention,

FIG. 2 is a downlink (a) in the mobile communication system of the embodiment.
And a diagram showing symbol timing of a transmission signal on the uplink (b),

FIG. 3 is a diagram showing an autocorrelation waveform of a signal modulated by a polyphase orthogonal sequence,

FIG. 4 is a diagram showing an odd cross-correlation waveform of a signal modulated by a polyphase orthogonal sequence,

FIG. 5 is a diagram showing a correlation waveform of a signal modulated by a polyphase orthogonal sequence,

FIG. 6 is a diagram showing a correlation waveform of a signal modulated by a polyphase orthogonal sequence having a chip shift;

FIG. 7 is a binary code (a) in spread spectrum communication.
And FIG. 6 is a diagram showing an autocorrelation waveform when using and a polyphase orthogonal sequence (b),

FIG. 8 is a diagram showing a phase plane of a polyphase orthogonal sequence;

FIG. 9 is a case where spreading is performed using a polyphase orthogonal sequence (a).
And (b) block diagram for despreading,

FIG. 10 is a block diagram showing an apparatus for implementing a conventional mobile communication system;

FIG. 11 is a diagram showing symbol timings of transmission signals of a downlink (a) and an uplink (b) in a conventional mobile communication system.

[Explanation of symbols]

 1, 50 Base station 2, 51 Mobile unit 3, 52, 64 Transmitter 4, 13 Control circuit 5, 54 Synchronization data generation circuit 6 Control data generation circuit 7, 26, 55, 56, 66 Spreading circuit 8, 27 Delay Circuit 9,57 Composite circuit 10,12,25,28,30,58,59,67,68 Radio section 11,29,53,65 Receiver section 14,18,20,31,60,62,69 Despreading circuit 15, 61, 70 Synchronous circuit 16 Delay detection circuit 17 UW detection circuit 18, 21, 32, 63, 71 Demodulation circuit 40, 42 Spread code PNi 41, 44 Spread code PNq 43, 45 Correlation circuit 46, 47 Adder circuit 48 Multiplier circuit

Claims (6)

[Claims] 1. In mobile communication in which spread spectrum multiple access communication is performed between a base station and a plurality of mobile devices by using a spread code of a polyphase orthogonal sequence, synchronization is applied to a downlink from the base station to the mobile devices. The common channel and the information channel corresponding to each mobile station are set, the signal of each information channel is delayed, and a chip shift occurs between the transmission symbol timing of the information channel and the symbol timing of the synchronization common channel. The mobile communication system is characterized in that the delay amount of each information channel is set so that the magnitude of the chip shift in each information channel at that time is uniformly distributed within the range of the chip shift setting width. 2. Each of the mobile stations sets a window capable of capturing the symbol timing of the own information channel based on the detected symbol timing of the synchronization common channel and the information on the chip shift in the own information channel, and the window is provided. The mobile communication system according to claim 1, wherein correlation detection is performed within the range. 3. A downlink from the base station to a mobile device,
The mobile communication system according to claim 1 or 2, further comprising a control channel for notifying a magnitude of a chip shift in each information channel. 4. The mobile device transmits an uplink signal from the mobile device to a base station at a transmission symbol timing obtained by adding a chip offset to the symbol timing of the synchronization common channel, and the base station, The mobile communication system according to claim 1, wherein a window that can capture the symbol timing of the information channel in the uplink is set, and correlation detection is performed within the range of the window. 5. The movement according to claim 4, wherein the magnitude of the chip shift added to the uplink signal is set to be equal to the magnitude of the chip shift of the own information channel in the downlink. Communication method. 6. The mobile communication system according to claim 2, wherein Rake reception is used to combine reception outputs that have been subjected to correlation detection within the window range.