JP2001274730A - Cdma communication system and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CDMA communication system by which the phase of a transmission signal from each terminal, so that reception signals sent from respective terminals are synchronized with each other in a base station. SOLUTION: A base station 401 detects the difference between a reference phase of a spread code and a code phase of a received signal sent from each terminal and feeds back a jump signal PJ-i, denoting a phase difference to each terminal 402. After the synchronization capture, the base station receives the signals at the reference phase and feeds back phase control information PC-i which is a phase difference between the phase of the received signal and the reference phase to each terminal. Each terminal makes rough adjustments of the phase of the spread code by using the jump signal and fine-adjusts the phase of the transmission signal, on the basis of the phase control information. Thus, the base station can synchronize the signals sent from each terminal in terms of the phases of the received signals and applies spread spectrum processing to the signals through incoming channels by using an orthogonal code. Since the base station can make the signals of each of the channels is the incoming channel orthogonal to each other and the CDMA communication system is realized, where interference among the terminals can completely be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CDMA (Code D)
The present invention relates to a communication system using ivision Multiple Access (code division multiple access) and a phase control method of a spreading code.

[0002]

2. Description of the Related Art The CDMA system is a system in which a plurality of communication channels are multiplexed in the same frequency band using a plurality of different types of spread spectrum codes (spreading codes). The signal is spread (spread) by multiplying the signal by a spreading code unique to each communication channel, and a multiplexed signal in which spread signals of a plurality of channels are mixed is transmitted at the same carrier frequency.

Each terminal device performs spectrum despreading (despreading) by multiplying a received signal by a code (despreading code) unique to each communication channel, which is the same as the spreading code used by the base station, and a correlation is obtained. Extracts only the signal of the own channel. At this time, since the spreading code and the despreading code of the signals of other channels are different from each other, they cannot be correlated with each other, but merely become noise components. No, the noise level can be reduced so as not to disturb the communication.

[0004] The CDMA system has been attracting much attention in recent years as a system for dramatically improving communication frequency utilization efficiency. For example, in the United States, the CDMA system is a standard system (IS-95) for digital cellular mobile communication systems. It has been adopted and has reached the stage of practical use. In the IS-95 system, an orthogonal code is used as a spreading code in a downlink used for signal transmission from a base station to each terminal device.

The orthogonal codes are, for example, codes W0 and W shown in FIG.
As shown by 1, W2, and W3, when a product-sum operation is performed for an arbitrary two codes of a code group over an orthogonal unit section,
It has the property that the result is 0.

Therefore, for example, as shown in FIG. 10, a plurality of base stations 401 connected to a wired network
(401-1 to 401-j) and a plurality of terminal devices 402 (402-1 to 40-40) located in the communication area of each base station.
2-n), each base station transmits a unique orthogonal code Wi (i = 1 to 4) to a plurality of terminal devices (or communication channels) in a communication area.
n), the signal or data to be transmitted to the terminal device i is spread by the unique orthogonal code Wi of the terminal device, and the terminal device i despreads the received signal using the orthogonal code Wi unique to itself. Then, the terminal device i can completely remove the signal components of all the channels other than its own reception channel in the process of the despreading process so that the terminal device i does not act as an interference signal. As described above, a communication system in which spread spectrum using orthogonal codes is applied to downlink communication from a base station to a terminal device is disclosed in, for example, US Pat. No. 5,103,459.

[0007]

In order to take advantage of the above-mentioned orthogonal code, in the course of the despreading process, the orthogonal code of one channel to be received is completely identical to the orthogonal code of the other channel in timing. It needs to be synchronized. If there is a difference in the timing of the orthogonal code between the multiplexed spread spectrum signals of a plurality of channels, the received signal component of another channel acts as a disturbing signal on the signal of its own channel due to the loss of orthogonality. , S / N deteriorates.

For this reason, in a conventional communication system using CDMA, orthogonal codes are used only in a 1: N transmission line in which timing synchronization of spread codes between channels is easy, that is, in a downlink from a base station to a terminal device. N-to-1 where a plurality of terminal devices transmit signals independently of each other
In the transmission uplink, non-orthogonal signals, for example, pseudo noise (P
N) The code is applied to spread the spectrum of the transmission signal.

In the uplink where each terminal device performs transmission operation independently of each other, even if each terminal device spreads the spectrum with an orthogonal code, the spread code is asynchronous between the channel signals received by the base station. Therefore, the channel signals interfere with each other, and the reception S / N deteriorates. For this reason, when orthogonal codes are applied to the uplink, the number of connection channels is restricted. For example, when an attempt is made to achieve a reception S / N of 10 dB, the number of connection channels in the uplink becomes about 1/10 of that in the downlink. I will.

An object of the present invention is to provide a CDMA communication system and a CDMA communication method that enable both a base station and each terminal device to receive a high-quality signal. It is another object of the present invention to provide a CDMA communication system capable of increasing the number of terminal devices capable of simultaneously communicating with a base station and a phase control method of a spreading code.

[0011]

In order to achieve the above object, in a CDMA communication system according to the present invention, a base station (or a base station) that forms a plurality of channels by CDMA (code division multiple access) on uplink and downlink respectively. In a communication system including a master station) and a plurality of terminal devices (or slave stations) respectively associated with a pair of channels of an uplink and a downlink, the base station is detected for each channel of the uplink. Means for feeding back information indicating the phase difference between the phase of the received signal and the reference phase of the despreading code on the base station side to each terminal device via the corresponding channel of the downlink, and each of the terminal devices Means for matching the spreading code phase of the transmission signal on the uplink to the reference phase on the base station side based on the phase difference information received on the corresponding channel of the downlink. And, characterized in that the application of the orthogonal code as spreading code for transmission signal to each of the uplink and downlink.

More specifically, according to the present invention, the transmission circuit of each terminal device is provided with orthogonal code generation means and orthogonal code phase control means, based on phase control information received from the base station on the downlink. The phase control means controls the phase of the orthogonal code for spreading the transmission signal so that the uplink channel signals are received by the base station in a state orthogonal to each other. In order to align the phases of the orthogonal codes of the respective terminal devices, the base station measures, for example, the phase difference between the reception reference phase in each channel of the uplink and the reception signal phase from each terminal device, and determines the phase according to the result. The control signal is fed back to each terminal device. Each terminal device extracts data addressed to the own station and a phase control signal addressed to the own station from the signals transmitted from the base station, and controls the spread code phase of the transmission signal based on the control signal. According to one embodiment of the present invention, when a terminal device is newly connected, the measurement result of the reception phase at the base station side is transmitted to the terminal device, and the terminal device transmits the spread code of the transmission signal based on the measurement result. Set the phase to a predetermined phase.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The base station 40 shown in FIG.
An embodiment of the present invention will be described with reference to an application example to a wireless communication system including a terminal device 1 and a terminal device 402. FIG. 1 shows an example of the configuration of the base station 401. A signal from each terminal device received by the antenna 111 is transmitted to the circulator 110
, And is input to the high-frequency circuit 109 and converted into a baseband spread spectrum signal Rx. The baseband spread-spectrum signal Rx is transmitted to a plurality of modems 106-
i (i = 1 to n).

Each of the modulation and demodulation devices 106-i receives the input signal R
x is subjected to demodulation processing and decoding processing by spectrum despreading, whereby a transmission signal (reception data 1
02) is taken out. Note that each modem 106-i
As will be described in detail with reference to FIG. 2, a PNr unique to the uplink generated from a pseudo-noise (PN) generator 211 for reception and a specific orthogonal code assigned to each terminal device generated from an orthogonal code generator 212. Two-stage spectrum despreading is performed using Wi. Further, each of the modulation and demodulation devices 106-i includes:
A synchronization acquisition circuit 214 that operates at the time of initial synchronization acquisition of a spread code (hereinafter, referred to as a search mode), and a reception phase state determination circuit 213 that operates at the time of phase control after the initial acquisition (hereinafter, referred to as a phase control mode). Is provided. When the initial synchronization acquisition of the spread code is completed in the search mode, the synchronization acquisition circuit 214 searches the search phase information SP-i (i = 1 to 1).
n) is output. On the other hand, in the phase control mode, the determination circuit 213 performs a comparison operation of the reception phase in parallel with the despreading process of the reception signal Rx, and performs the phase difference information PD-i
(I = 1 to n) is output.

The search phase information SP-i (i = 1 to n) and the phase difference information PD-i (i = 1 to n) output from each modem 106-i (i = 1 to n) are transmitted upward. It is input to the phase control device 103. The uplink phase control device 103 determines, according to the content of the search phase information SP-i (i = 1 to n),
Phase jump information PJ-i (i = 1 to 1) for each terminal device
n) and generates a phase control instruction signal PC-i for each terminal device according to the content of the phase difference information PD-i (i = 1 to n).
(I = 1 to n). The transmission data 101 addressed to each terminal device is transmitted to the modem 106-i (i = 1 to n) by the phase jump information PJ-i or the phase jump information PJ-i for each terminal device selectively given from the uplink phase control device 103. The signal is mixed with the control instruction signal PC-i and undergoes an encoding process and a modulation process by spread spectrum. The spread spectrum is performed in two steps using a pseudo noise PNf inherent to the downlink generated by a pseudo noise (Tx-PN) generator 104 and an orthogonal code Wi generated for each terminal device from an orthogonal code generator 105. And a signal modulated by spread spectrum is output as a transmission signal Tx-i (i = 1 to n). A transmission signal Tx-i (i = 1) for each terminal device
To n) are sequentially added by a cascade-connected adder 107, converted into a signal in a transmission frequency band by a high-frequency circuit 108, and transmitted via a circulator 110 and an antenna 111.

FIG. 2 is a block diagram of each of the modems 10 shown in FIG.
6 shows an example of the configuration of 6-i (i = 1 to n). The transmission data 101 and the phase jump information PJ-i (i = 1 to n) or the phase control information PC-i (i = 1 to n) output from the uplink phase control device 103 are mixed in the frame constructor 201. After that, the encoder 202 undergoes encoding processing such as error correction. The coded signal is multiplied by an orthogonal code Wi assigned to a terminal device serving as a transmission destination by a first multiplier 203 and subjected to a first-order spread spectrum processing, and then a second multiplier 204, the signal is multiplied by the downlink pseudo noise PNf and subjected to the second-order spread spectrum.
Output as xi.

On the other hand, the received signal Rx is applied to the first multiplier 20
6 and is multiplied by the orthogonal code Wi generated by the orthogonal code generator 212 and subjected to a first-order despreading process. The orthogonal code Wi is the same as the orthogonal code Wi used by the transmission source terminal device of the received signal Rx to spread the signal Rx. The output of the multiplier 206 is the second multiplier 207
, And is multiplied by the uplink pseudo-noise PNr generated by the pseudo-noise (PN) generator 211 and subjected to a second-order despreading process.

The output of the multiplier 207 is output to an accumulator 208
Are input to the decoder 209 and the synchronization supplementary circuit 214. The accumulation period of the signal performed by the accumulator 208 is, for example, 8 in the search mode.
The symbol period is one symbol period in the phase control mode, and the accumulation period is switched depending on the mode. Note that, in the search mode, for example, when the terminal device
The base station transmits the result of despreading of the received signal to 8
If accumulation is performed over the symbol period, the gain of the correlation value can be increased by 9 dB, and the initial synchronization acquisition probability can be increased.

Synchronization acquisition circuit 214 performs despreading of received signal Rx output from accumulator 208 when the spreading code of the terminal device and the spreading code of the base station are in an asynchronous state, that is, in a search mode state on the uplink. A synchronization determination is made based on the result. At this time, the changeover switch SW is connected to the synchronization acquisition circuit side so that the control signal output from the synchronization acquisition circuit 214 is input to the PN generator 211 and the orthogonal code generator 212 of the reception phase state determination circuit 213. It is in a state where

From the output of the accumulator 208, a multiplier 206,
207 and the received signal Rx
When it is determined that the phase with the spread code is asynchronous, the synchronization acquisition circuit 214 issues a phase update command to the PN generator 211 and the orthogonal code generator 212 to shift the respective phases by a predetermined amount. Output. If it is determined that the synchronization state has been reached, the synchronization acquisition circuit 214
PN generator 211 and orthogonal code generator 2 at that time
The difference between the reference phase and the reference phase is calculated and output as search phase information SP-i for notifying the difference to the terminal device. In the search mode (asynchronous), the decoder 209
Is output as invalid data.

When it is found that the spread codes are synchronized, the synchronization acquisition circuit 214 connects the changeover switch SW to the reference value generator (here, indicated by the value "0"), and
The phases of the N generator 211 and the orthogonal code generator 212 are set as reference phases, respectively, and the mode transits to the phase control mode. The despread reception signal output from the accumulator 208 in the phase control mode is subjected to decoding processing such as error correction in the decoder 209, and is then extracted as valid reception data 102.

The reception phase state determination circuit 213 enclosed by a dotted line in FIG. 2 is for determining the phase of the reception signal Rx.
The received signal Rx is despread by a spreading code having a phase advanced by 1/2 chip and a phase delayed by 1/2 chip with respect to the spreading code (PN and orthogonal code) used in 6, 207,
The difference between the accumulated values of the respective despread results (correlation values) is output as phase difference information PD-i.

In the circuit 213 shown in FIG. 2, the outputs of the PN generator 211 and the orthogonal code generator 212 are respectively passed through cascade-connected two-stage 1 / 2-chip delay circuits 210, so that two delay circuits are provided. With reference to the phase of the spread code taken out between them, the spread code (P
N and an orthogonal code), the leading phase spreading code is supplied to multipliers 206 and 207, and the lagging phase spreading code is supplied to multiplier 20 and 207.
6, and 207, respectively, and multiplied by the received signal Rx. The result of the despreading of these two sequences is the received data 1
02, and accumulators 208, 208
Are integrated at predetermined intervals, and the difference is integrated into the phase difference information PD-i.
Is output as

FIG. 3 shows an example of the configuration of the terminal device 402. The signal received from the antenna 301 is input to the high frequency circuit 303 via the circulator 302, and is converted into a baseband spread spectrum signal. The baseband spread spectrum signal is received by a receiving circuit (demodulation circuit).
Is multiplied by the downlink pseudo-noise PNf generated from the pseudo-noise (PN) generator 312, and undergoes a first-order despreading process. The PN generator 312 is set with a noise pattern such that the pseudo noise PNf is the same as the pseudo noise PNf inherent to the downlink generated at the base station.

The output of the first multiplier 304 is multiplied in a second multiplier 305 by the orthogonal code Wi for the terminal device generated from the orthogonal code generator 313, and subjected to a second-order despreading process. receive. The output of the second multiplier 306 is input to the accumulator 306 to accumulate signals for a certain period,
The accumulated signal is supplied to the frame controller 308 after being decoded by the decoder 307 such as error correction.

The frame control unit 308 includes a decoder 307
Of the received data 309 and the phase jump signal PJ-i
Alternatively, it is separated into a phase control signal PC-i. The phase jump signal PJ-i is input to an orthogonal code generator 318 and a pseudo-noise generator 321 of a transmission circuit (modulation circuit), and an orthogonal code used for spread spectrum of transmission data according to the phase jump signal PJ-i. The phases of Wi and the pseudo noise PNr are roughly adjusted. On the other hand, the phase control signal PC-i is input to the transmission phase control device 315. Transmission phase control device 3
Reference numeral 15 outputs a control signal PS-i for finely adjusting the phases of the orthogonal code Wi and the pseudo noise PNr according to the phase control signal PC-i.

The PN used in the despreading process of the receiving circuit described above.
The synchronization acquisition and holding operation of the orthogonal code and the orthogonal code are performed by a synchronization acquisition circuit 314 and a DLL (Delay Lock Loo
p) performed by 310 circuits. DLL circuit 310
PN is the same as the reception phase state determination circuit 213 of the base station.
The outputs of the generator 312 and the orthogonal code generator 313 are supplied to a two-stage 1/2 chip delay circuit 311 respectively, and the output of the spread code (PN and orthogonal code) used for the despreading process for the received data is ２. The spreading codes of the chip advance phase and the 1/2 chip delay phase are obtained.

When the phase of the received signal and the phase of the spread code for despreading are asynchronous (at the time of synchronous acquisition), the PN generator 312 and the orthogonal code generator 313 are connected to the synchronous acquisition circuit 314 connected via the switch SW. Is controlled by the phase update command. When the phase is synchronized, the PN generator 312
And the orthogonal code generator 313 are connected to the loop filter 315. In this state, the multiplier 3 uses the spread code of the 1/2 chip advance phase and 1/2 chip delay phase described above.
04 and 305, and 304 and 305, the received signal is despread, and the phases of the PN and orthogonal code are set so that the despread results of the two leading and lagging sequences obtained by the accumulators 306 and 306 have the same value. Controlled.

On the other hand, in the transmission circuit, the transmission data 306 is input to the encoder 317 and subjected to encoding processing such as error correction, and then spread by two multipliers 320 and 322. The first multiplier 320 performs first-order spread spectrum modulation by multiplying the encoded transmission data by the orthogonal code Wi assigned to the terminal device. , Pseudo noise P for uplink
A second-order spread spectrum modulation is performed by multiplying by Nr. In the present embodiment, the orthogonal code Wi generated from the orthogonal code generator 318 and the pseudo noise PNr generated from the pseudo noise generator 321 are converted into delay circuits 319 and 31 respectively.
9, the signal is supplied to multipliers 320 and 322, and the amount of signal delay in these delay circuits is controlled by the control signal PS-i output from the transmission phase control device 315, whereby the phase is finely adjusted. The output signal of the second multiplier 322 is converted into a signal in a transmission frequency band by a high frequency circuit 323, and then the signal is output to the antenna 30 via the circulator 302.
Sent to 1.

According to the above embodiment, each terminal in the base station performs the phase jump control performed when the base station shifts from the search mode to the phase control mode and the transmission phase control performed by each terminal device in the phase control mode. Since the phases of the signals received from the devices can be made uniform, the characteristics of the orthogonal code can be utilized, and the transmission signals from the terminals can be prevented from interfering with each other.

In the above-described embodiment, the base station sets an arbitrary reception phase as a reference phase, and controls the transmission phase of each terminal device to match the reference phase. After synchronization acquisition, the PN generator 2 for reception shown in FIG.
The phase of the PN generated from 11 and the phase of the orthogonal code generated from the orthogonal code generator 212 are fixed to the above-mentioned arbitrary reference phase, and the despreading process of the received signal is performed with this reference phase. However, the phase of the orthogonal code and PN used in the transmission circuit of the base station may be applied as the reference phase.

Next, a second embodiment of the present invention will be described. FIG. 4 shows the configuration of the base station 401. Components corresponding to those in FIG. 1 are denoted by the same reference numerals as in FIG. Second
The configuration and operation of the base station in this embodiment are similar to those of the base station of the above-described embodiment (hereinafter, referred to as the first embodiment), and the difference is that any of the modems (in this example, 1
The modulation / demodulation device 116-1) controls the phase of the transmission signal of another terminal device using the phase of the transmission signal received from one terminal device as a reference phase.

Referring to FIG. 4, the modem 116-1 includes:
A DLL circuit is provided, and while performing phase control of the PN and the orthogonal code so as to synchronize with the reception signal from the terminal device, the reception signal is despread, and the PN at the time when the synchronization is acquired is obtained.
And the spread code timing information CT based on the phase control signal of the orthogonal code. Another modem 116-
i (i = 2 to n) is the spreading code timing information CT
, The reference phase of each reception spreading code (PN and orthogonal code) is set, and the above-described despreading process in the phase control mode and the determination of the reception phase are performed.

FIG. 5 shows an example of the configuration of the first modem 116-1 in FIG. 4 for detecting the reference phase. FIG.
Is different from the modulation / demodulation device shown in FIG.
3, the phase control is performed by the control signal from the synchronization acquisition circuit 214 in the search mode, and the feedback control is performed by the output of the loop filter 215 in the phase control mode, as in the DLL circuit 310 of FIG. , The values of the phase jump signal PJ-1 and the phase control information PC-1 addressed to the terminal device are set to zero, and the feedback of the phase control information to the terminal side is eliminated.

The received signal phase at the time of synchronization acquisition detected by the synchronization acquisition circuit is set in the loop filter 215, and the PN generator 211 and the orthogonal code generator 21 are used starting from this phase.
2 are feedback-controlled, and the current phases of these encoders are sent to other modems 116-i (i = 2 to n) as spreading code timing information CT.

FIG. 6 shows a modulation / demodulation device 116-i (i = 2 to n) other than the first modulation / demodulation device 116-1 in FIG.
An example of the configuration will be shown. In the search mode, when the synchronization acquisition circuit 214 acquires the synchronization, the PN generator 211
The difference between the current phase of the orthogonal code generator 212 and the reference phase indicated by the spread code timing signal CT is the search phase information SP-i. After synchronization acquisition, the PN generator 211 and the orthogonal code generator 212 of the phase state determination circuit 224 are used.
However, feedback control is performed using the phase given by the spreading code timing signal CT as a reference phase. Unlike the first modem 116-1, in these modems, the search phase information SP-i and the phase difference information PD-i are:
Jump information PJ-i and phase control information PC-i, respectively
Is fed back to the terminal device side.

According to the configuration and control operation of the base station, the first
Using the reception phase from the terminal device corresponding to the modem 116-1 as the reference phase, the synchronization control of the reception signals from other terminal devices is performed, and the base station receives signals from each terminal device in a state where they are orthogonal to each other. To reach.

Next, a third embodiment of the present invention will be described. In this embodiment, an initial synchronization acquisition operation of a spread code is performed by changing the transmission phase of the spread code on the terminal device side in the search mode. In the following description, it is assumed that the uplink reception reference phase at the base station is equal to the transmission phase.

FIG. 7 shows the configuration of a base station 401 according to a third embodiment of the present invention. Components corresponding to those of the first embodiment shown in FIG. 1 are denoted by the same reference numerals. Base station 40
Reference numeral 1 denotes an operation in the phase control mode similar to that of the first embodiment, and an operation in the search mode is different as described later. In this embodiment, each modem 126-i (i =
1 to n) to the upstream phase control apparatus 103 are input to the phase difference information PD-i (i = 1 to 1) generated in the phase control mode.
n), and the search phase information SP-i generated in the search mode is, as shown in FIG.
6-i, it is directly supplied to the frame configuration circuit 201 as phase control information PC-i.

FIG. 8 shows an example of the configuration of the modem 126-i. As is apparent from comparison with FIG. 2, in the modulation / demodulation device 126-I of the present embodiment, the reception phase state determination circuit 23
3 despreads the received signal Rx with a fixed spreading code (PN and orthogonal code) output from the PN generator 211 and the orthogonal code generator 212 without receiving an external control signal. This is because, in the search mode, the terminal device performs the transmission operation while changing the phase of the spread code, and the base station side performs active acquisition while changing the phase of the spread code. Not functioning. The phase of the PN code PNr generated from the PN generator 211 and the orthogonal code Wi generated from the orthogonal code generator 212
Are fixed to the reference phase, respectively, and it is detected that the phase of the received signal Rx is synchronized with the reference phase, and the received data 102 is made valid. The accumulation section of the accumulator 238 to which the result of the despreading of the received signal Rx is input is the first
Similarly to the embodiment, for example, 8 symbols are used in the search mode, and 1 symbol is used in the phase control mode, and switching is performed depending on the mode.

In this embodiment, in the search mode, the accumulator 238 truncates the minute period required for the phase update on the terminal device side, for example, the despread result of one symbol, and the actual accumulation interval is seven symbols. So that In the search mode, each terminal device transmits, for example, continuous data of all “1”, and the base station avoids transmission bits in the phase update period in the terminal device and accumulates despread results for seven symbol periods. By performing the calculation, the gain of the correlation value can be increased by 8.5 dB, whereby the probability of initial synchronization acquisition can be improved. The accumulation timing of the despread result in the accumulator 238 is determined by considering the delay time until the signal transmitted from the terminal device reaches the base station.
Determined for each modem.

In the search mode, the result of the despreading of the received signal Rx is input to the synchronization acquisition determining circuit 234, and it is determined whether or not synchronization has been acquired based on the correlation value of the result of the despreading.
The determination result is output to the frame builder 201 as search control information SC-i (i = 1 to n). The search control information SC-i becomes a signal notifying the end of the search mode when the synchronization is captured, and a signal notifying the continuation of the search mode when the synchronization is determined to be non-synchronized. Sent.

FIG. 9 shows a terminal device 4 according to the third embodiment.
02 shows an example of the configuration, and components corresponding to those of the first and second embodiments shown in FIG. 3 are denoted by the same reference numerals. In this embodiment, the frame control device 308 searches the base station for the search control information S mixed with the received data and transmitted.
Ci (i = 1 to n) is extracted and input to the orthogonal code generator 318 and the PN generator 321 of the transmission circuit. The orthogonal code generator 318 and the PN generator 321 provide the orthogonal code Wi and the PN code PN according to the content of the search control information SC-i.
Control the phase of r.

While the search control information SC-i indicates the continuation of the search mode, for example, the phases of the orthogonal code Wi and the PN code PNr are changed in synchronization with the timing of the accumulator 306 of the receiving circuit. If the search mode end signal is detected by sequentially sliding by 1/2 chip, the orthogonal code Wi and the PN code P at the next phase slide timing.
By returning the phase of Nr by an integral multiple of 1/2 chip, it is synchronized with the despreading code phase on the base station side. The phase returning operation takes into account the phase sliding of the spreading code performed by the terminal device within the delay time from when the base station makes a synchronization determination to when the search mode ends reaches the terminal device. Immediately after the search mode is completed, the mode is shifted to the phase control mode, and the same phase control as in the first and second embodiments is performed.

According to the first to third embodiments described above,
Downlink and uplink channel signals can be orthogonalized to each other, so that both the terminal device and the base station can receive the target channel signal with high quality without being disturbed by other channel signals. Can be processed. Also, going up,
By applying orthogonal codes to both downlink lines, it is possible to increase the number of terminal devices capable of simultaneously communicating with the base station, and accommodate a maximum number of terminals equal to the spreading ratio.

When the present invention is applied to a cellular mobile communication system, phase control may be performed in a cycle shorter than a time change of a communication state of a terminal device (effect of fading or Doppler frequency shift). In the embodiment, the orthogonal code to be assigned to each terminal device has been described as the same code for both the uplink and downlink lines. However, different orthogonal codes may be assigned to the individual lines.

In the embodiment, the configuration of the base station and the terminal device to which the present invention is applied has been described on the premise of the wireless communication system shown in FIG. 10, but the present invention is applicable to other types of communication systems, for example, FIG. As shown in FIG. 1, a switching base station (PHS switching station) 403 of a portable telephone (Personal Handyphone System: PHS) and a plurality of terminal relay stations 404 are connected via a CATV network, and two-way communication is performed by a CDMA method. The present invention can also be applied to a system (CDMA / C system). In the case of the system of FIG. 12, the exchange 403 is the base station 401 described above, and each relay station 404 is the terminal device 40 described above.
2, the antenna 111 of the base station and the antenna 301 of the terminal device may be replaced with a cable. In addition, the present invention can be applied to other forms of wireless communication systems such as a wireless local loop (WLL) system in which a base station and each terminal device are installed at fixed positions.

[0048]

As is apparent from the above description, according to the present invention, it is possible to spread the spectrum of a transmission signal using orthogonal codes in the uplink, and to make the signals of the respective channels orthogonal to each other at the base station. Since reception is possible, a high-quality CDMA communication system in which signals received from the terminal devices do not mutually interfere can be realized. Further, according to the present invention, since signals of each channel can be orthogonalized in both uplink and downlink lines, a communication system capable of increasing the number of terminal devices accommodated per base station can be configured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a base station constituting a communication system of the present invention.

FIG. 2 is a diagram showing details of a modem 106-i (i = 1 to n) in FIG. 1;

FIG. 3 is a configuration diagram showing one embodiment of a terminal device in the communication system of the present invention.

FIG. 4 is a configuration diagram showing a second embodiment of the base station.

FIG. 5 is a detailed view of the modem 116-1 in FIG. 4;

FIG. 6 shows another modulation and demodulation device 116-i (i =
FIG.

FIG. 7 is a configuration diagram showing a third embodiment of the base station.

FIG. 8 is a diagram showing details of a modulation / demodulation device 126-i (i = 1 to n) in FIG. 7;

FIG. 9 is a configuration diagram showing a third embodiment of the terminal device.

FIG. 10 is a diagram showing an example of a communication system to which the present invention is applied.

FIG. 11 is a diagram for explaining orthogonal codes used for spread spectrum.

FIG. 12 is a diagram showing an example of another communication system to which the present invention is applied.

[Explanation of symbols]

101, 316: transmission data, 102, 309: reception data, 103: uplink phase control device, 104, 211, 3
12, 321 ... PN generator, 105, 212, 313,
318: orthogonal code generator, 106, 116, 126: modulator / demodulator, 107: adder, 108, 323: high-frequency circuit for transmission, 109, 303: high-frequency circuit for reception, 11
0, 302: circulator, 111, 301: antenna, 201: frame configuration device, 202, 317: encoder, 203, 320 ... first spreading multiplier, 204,
322: multiplier for secondary spreading, 206, 304 ... multiplier for primary despreading, 207, 305: multiplier for secondary despreading, 208, 306 ... accumulator, 209, 307 ... decoding , 210, 311... 1/2 chip delay unit, 213, 2
24, 233... Reception phase state determination circuit, 214, 314
... Synchronization acquisition circuit, 215, 315 ... Loop filter, 2
23 ... reception phase state determination circuit, 234 ... synchronization acquisition determination circuit, 308 ... frame control device, 310 ... DLL, 31
5 ... Transmission phase control device, 319 ... Delay circuit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinnobu Doi 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo Inside the Central Research Laboratory, Hitachi, Ltd. Hitachi Kokusai Electric Co., Ltd.

Claims (5)

[Claims] 1. A master station for communicating with a slave station through an uplink channel and a downlink channel by a spread spectrum method,
A demodulator that despreads a received signal transmitted from the slave station through an uplink channel, performs initial synchronization acquisition of the received signal, and generates a phase difference between a phase of a spreading code corresponding to the uplink channel of the received signal and a reference phase. And a synchronization acquisition circuit that detects a first phase difference, performs synchronization holding of the received signal, and a second phase difference between the phase of the spread code corresponding to the uplink channel of the received signal and the reference phase. A phase state determination circuit that detects a phase difference of the first phase difference information indicating the first phase difference and a phase control device that generates second phase difference information indicating the second phase difference, A modulator for spreading the first or second phase difference information using a spreading code corresponding to a downlink channel for transmitting the first or second phase difference information. 2. The master station according to claim 1, wherein said spreading codes are assigned by orthogonal code groups orthogonal to each other. 3. The master station according to claim 1, wherein the modulator has the same reference phase as the phase of a spreading code for spreading the first or second phase information. Master station characterized by setting. 4. The master station according to claim 1, wherein the reference phase is set to the same phase as a phase of a spread code of a transmission signal transmitted from any of the slave stations. Main station to be characterized. 5. The master station according to claim 1, wherein the demodulator determines an initial synchronization acquisition state by setting a cumulative section in the despreading processing of the received signal longer than one symbol period. A master station characterized by the following.