JPH07170223A - System and device for cdma mobile communication - Google Patents

Abstract

PURPOSE:To prevent the throughput of a traffic channel from being lowered and to eliminate the malfunction of a PLL and characteristic degradation at the reception part of a mobile station by inserting a unique word for frame synchronism to a pilot to be a reference signal for each frame cycle. CONSTITUTION:The transmission part of a base station inserts the unique word, which is generated by a unique word inserting part 26, to pilot data generated from a data generating part 21 for each frame cycle at a pilot channel. Afterwards, circuits 22 and 23 perform phase modulation and spectrum diffusion. At the reception part of the mobile station, a radio signal transmitted from the base station is carrier-demodulated by a demodulation circuit 31 and inversely diffused later by an inverse spectrum diffusion circuit 32. At a frame synchronizing circuit 34, the unique word is searched while using a pilot ch phase- corrected by a subordinate synchronizing detection demodulating part 33a and a frame head detect signal is outputted to the subordinate synchronizing detection demodulating part 33a so that the received data can be demodulated at suitable timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to code division multiple access (CDMA) using spread spectrum communication.
Ion multiple access mobile communication system, and particularly a CDM excellent in throughput of a traffic channel (communication channel for data transmission)
A mobile communication system, a base station, and a mobile station apparatus.

[0002]

2. Description of the Related Art In a CDMA cellular mobile radio communication system using spread spectrum, for example, as shown in FIG.
All the mobile stations 101 to 106 existing in 15 and 16 are managed, and communication between the mobile stations is performed via the base station. The wireless line control station 17 is connected as an upper layer of the base station, and controls exchange between the mobile station that has made a communication request and the partner station. A pilot signal is constantly transmitted on the communication line (forward link) from the base station to the mobile station. The pilot signal serves as an important reference signal for the mobile station, and the mobile station performs processing such as data demodulation, power control, and handoff with this reference signal.

For example, in the case of the mobile station 103 located near the cell boundary of FIG.
It is realized by comparing the received power of the pilot signal from the base station 11 that manages the adjacent cell 15 with the received power of the pilot signal from the base station 12 that manages the adjacent cell 15 and switching the connection to the larger base station. .

FIG. 2 shows a general configuration of a base station transmitter and a mobile station receiver. The pilot signal is data (generally all “0” or all “1”) generated by the pilot data generator 21 in the pilot channel.
(Known digital sequence of) is digitally modulated by the phase modulator 22.

In the traffic channel, in synchronization with the pilot signal, the data signals addressed to the mobile stations 1 to n output from the data generator 27 are phase-modulated by the phase modulator 22 and then spread in spectrum. The synchronization channel is a dedicated channel for frame synchronization, the synchronization channel data section 25 generates synchronization ch data in synchronization with the pilot channel, and the phase modulation section 22 phase-modulates this.
In the sync channel, sync ch data is transmitted in a frame structure having a unique word as a header.

The unique word is a special digital sequence, and on the receiving side, it is captured by the frame synchronization processing in the demodulation section, and the head of the frame is correctly detected from the header phase at the time of capture, so that the data is recorded at appropriate timing. Can be demodulated.

The output of each channel is the spread spectrum section 2
The spectrum is spread in 3 and multiplexed in the multiplexing unit 24. Each spread spectrum unit 23 uses an orthogonal code (a pseudo-random code multiplied by a Walsh code) to distinguish between pilot, traffic, and synchronization channels. The signal after the spread spectrum is carrier-modulated by the carrier modulator 28 and is wirelessly transmitted via the antenna 29.

On the other hand, in the mobile station, the radio signal from the base station is received via the antenna 30, demodulated by the carrier demodulation section 31, and then, in the spectrum despreading section 32, the phase is synchronized with the phase of the base station. Despreading is performed using orthogonal codes. In this despreading, each channel of pilot, synchronization, and traffic can be easily selected and extracted by using the orthogonal code assigned to the base station. The outputs (pilot ch, traffic ch, synchronization ch) of each channel after spectrum despreading are two-dimensional baseband signals I and Q. Data demodulation is performed by the quasi-coherent detection demodulation unit 3
3 is realized by synchronously demodulating the traffic channel with reference to the phase of the pilot signal.

Generally, a mobile station needs to know the absolute phase of a pilot signal when demodulating data. The quasi-synchronous detection demodulation is a useful means for achieving this purpose, and is to detect and demodulate by reproducing the frequency and phase synchronized with the received signal using a PLL (Phase Locked Loop). In the frame synchronization unit 34, the quasi-synchronization detection demodulation unit 3
A frame start detection signal is output by searching for a unique word from the phase-corrected synchronization ch output from the circuit 3. The frame head detection signal enables the quasi-synchronous detection demodulation to restore the received data at the correct timing.

Prior art related to this type of device is, for example, US Patent Qualcomm, Inc .: System and Method for Generating Signal Waveforms in ACDM Cellular Telephone System (SYSTEM AND METHOD).
FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULA
R TELEPHONE SYSTEM, USPATENT NO.5103459, AP
R. 7, 1992).

[0011]

However, in the prior art, as shown in FIG. 2, since the frame synchronization channel occupies one traffic channel, the loss of the number of simultaneous calls and the throughput. Cause a decrease in

As described in detail in the embodiments of the present invention, the above problem is solved by a method of inserting a unique word only in the pilot channel in the base station transmitter. In this case, if the pilot signal contains data whose phase changes irregularly like a unique word, a phase error larger than the actual phase error is output, which deteriorates the characteristics of the PLL, as described below. Problem occurs.

FIG. 3 shows an example of a pilot frame structure in which a unique word is inserted. Here, each of the pilot signals I and Q constitutes a frame of 960 bits, of which the first 32 bits are assigned a unique word as a special sequence and the remaining part is assigned pilot data.

For a frame having such a structure,
For example, when the QPSK modulation shown in FIG. 4 is performed, the pilot data (all “0”) is transmitted as the signal point A and the unique word is transmitted as the signal point A or C. Therefore, when a unique word is received, the reception point after normalization becomes P for "0" and P'for "1" as shown in FIG.

Here, the reason why the receiving point does not completely coincide with the signal point A or C is that transmission line noise, fading, PL
This is due to the influence of deterioration factors due to L phase control errors and the like.
That is, P ′ is a reception point that is not originally expected as pilot data, and the phase error of the reception point P ′ with respect to the reference signal point A becomes close to 180 degrees. This is a PLL
Cause malfunction of.

In the prior art, the problem can be solved to some extent by making the time constant of the loop filter sufficiently long and slowing the followability to abrupt phase fluctuation, but the effect of the phase error is completely eliminated. It cannot be lost.
For this reason, the decoding error rate characteristic deteriorates, and if the time constant is made too long, the followability to the phase fluctuation of the received signal deteriorates. That is, the conventional quasi-coherent detection demodulator has a problem that it is weak against a large phase variation and it is difficult to optimally set the PLL parameter.

It is an object of the present invention to provide a CDMA mobile communication system which prevents the throughput of traffic channels from decreasing.

Another object of the present invention is to provide P in the receiving section of the mobile station even when there is a large phase variation in the received signal.
An object of the present invention is to provide a CDMA mobile communication system without malfunction of LL and deterioration of characteristics.

Another object of the present invention is to provide a new structure of a base station and a mobile station in a CDMA mobile communication system.

[0020]

In order to achieve the above object, in a CDMA mobile communication system of the present invention, a base station inserts a unique word for frame synchronization into a pilot serving as a reference signal for each frame period. , The pilot signal and the traffic channel data are respectively phase-modulated and spectrum-spread, and then multiplexed and transmitted in the air. On the other hand, each mobile station extracts a frame synchronization signal from the received signal of the pilot channel and demodulates the data from the received signal of the traffic channel based on the frame synchronization signal.

More specifically, the receiving section of each mobile station is provided with a quasi-synchronous detection demodulator including a synchronization state monitoring means, a switching control means, and a phase error determination means. Whether or not the frequency and phase between the received signals are synchronized is constantly monitored, and appropriate phase difference correction is performed according to the state.

The synchronization state monitoring means considers an error state when the phase difference between the received signal and the reference signal in the apparatus is a set value or more, and the average error rate is higher than a preset allowable value. If it is smaller, it is determined to be in the synchronous state, and otherwise it is determined to be in the asynchronous state. When in the synchronized state, the switching control means determines whether or not the phase difference between the received signal and the in-apparatus reference signal is greater than or equal to the set value by the phase error determination means, and if it is greater than or equal to the set value, sets it to 0. , PLL after inverting the phase of the received signal
Is operated, and if not, the mode for performing normal processing is selected by using the phase difference as input to the PLL. on the other hand,
When in the asynchronous state, the switching control means selects the normal pull-in operation mode until the synchronous state is restored again.

[0023]

According to the structure of the present invention, since the transmitter of the base station only needs to insert the unique word into the pilot channel, the synchronization channel becomes unnecessary, and as a result, the throughput can be improved. Also, in the receiver of the mobile station,
Higher transmission power than traffic channel (typically 10d
It is possible to establish frame synchronization by using a pilot channel output at about B or higher), and to achieve higher S / N than before.
Data can be demodulated by (signal to noise power ratio).

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a CDMA mobile communication system according to the present invention will be described below with reference to the drawings.

FIG. 5 shows the configurations of a transmitter of a base station and a receiver of a mobile station, which are the main parts of a CDMA mobile communication system according to the present invention. In the figure, in the pilot channel, the transmitter of the base station inserts the unique word generated by the unique word inserter 26 into the pilot data generated by the data generator 21 every frame period (see FIG. 3). After that, the circuits 22 and 23 perform phase modulation and spread spectrum. The traffic channel is the same as that of the conventional system, and the data generator 27 generates data addressed to the mobile stations 1 to n, and the circuits 22 and 23 perform phase modulation and spread spectrum. The output of the pilot channel and the output of the traffic channel are synchronously multiplexed by the multiplexing circuit 24, and the multiplexed signal is carrier-modulated by the modulation circuit 28 and then transmitted as a radio signal from the antenna 29. .

In the present invention, since the transmitter of the base station has a frame structure in which a unique word is inserted in the pilot, it is not necessary to prepare a channel dedicated to frame synchronization as in the conventional system. Therefore, each mobile station can establish frame synchronization with the pilot, and as a result, it is possible to eliminate traffic channel loss.

In the receiving section of the mobile station, the radio signal transmitted from the base station is received by the antenna 30, the carrier is demodulated by the demodulation circuit 31, and the spectrum is then despread by the spectrum despreading circuit 32. The despread output is a two-dimensional baseband signal I, Q.
And each channel (pilot ch, traffic c
h) can be easily selected and extracted by the orthogonal code. The output of each channel is the quasi-coherent detection demodulator 33a.
Entered in. The frame synchronization circuit 34 searches for a unique word by using the pilot ch whose phase has been corrected by the quasi-synchronous detection demodulation unit 33a, and outputs a frame head detection signal to the quasi-synchronization detection demodulation unit 33a so that the timing is appropriate. Demodulate the received data.

As described above, in the above CDMA modulation / demodulation, since the unique word is mixed in the pilot transmitted by the base station, in the quasi-coherent detection demodulation on the mobile station side, every frame period due to the unique word Large phase fluctuations cause malfunctions. This problem can be solved by configuring the quasi-coherent detection demodulator 33a as follows, for example.

FIG. 6 shows an example of the configuration of the quasi-coherent detection demodulator. In the figure, Xi and Xq are spectrum despread outputs of the pilot signal (with a unique word inserted) and represent the in-phase component I and the quadrature component Q of the baseband, respectively (see FIG. 5). Pilot despread output Xi, X
The phase correction unit 1 performs phase rotation on q, and corrects q into Yi and Yq. The amount of phase rotation is VCO (Voltage Contro
lled Oscillator) 7 output value φn (n is time), more specifically, a signal generated by generating a sine wave (COSφ
n, SINφn).

The outputs Yi and Yq after the phase correction are sent to the amplitude normalization unit 2 as pilot demodulation signals, and the amplitude normalization unit 2 calculates Yi and Yq respectively as the square root of the sum of squares thereof (that is, the distance from the origin). ), Output Y
i ', Yq' are obtained.

In the present invention, Yi and Yq are input to the frame synchronization 34, and the frame head detection signal is obtained from the pilot signal. Here, the frame head detection signal is a rectangular pulse signal having a 1-bit width that is output each time the head bit of the frame arrives, and is input to the data demodulation unit 9. In the phase difference calculation unit 3, the amplitude normalized output Y
The phase difference Δφn between i ′, Yq ′ and the reference signal 4 is calculated,
Output. Here, the reference signal is a signal expected as an ideal pilot reception signal (all "0" or all "1" digital sequence, but is assumed to be all "0" here), and the reference signal in FIG. It corresponds to the signal point A. That is, Δφn corresponds to the phase of the reception point P (Yi ′, Yq ′) after the normalization with respect to the reference signal point A. As a modulation method, QPSK (Qu
Adruple Phase Shift Keying) is used, and FIG. 4 shows the signal point arrangement.

In the present embodiment, the mobile station comprises a synchronization state monitoring unit 10, a switching control unit 11, a phase difference determination unit 12, and a phase difference correction 2 (51). Sync status monitor 1
At 0, as will be described later in detail, the value of the phase error is constantly monitored, and the average probability of synchronization (hereinafter, referred to as “synchronization rate”) is estimated based on the value. The synchronous / asynchronous judgment is performed as follows.

That is, if the synchronization rate is less than or equal to a preset allowable value, it is determined to be in the synchronous state, and conversely, if the synchronization rate continuously exceeds the allowable value for a certain monitoring period, the asynchronous state is determined. to decide. The asynchronous state usually occurs in the initial state immediately after turning on the power of the apparatus or when the synchronization is lost for some reason.

In the synchronized state, the switch control unit 11 connects the switch to the side b and inputs the phase difference Δφn signal to the phase difference determination unit 12. The phase difference determination unit 12 compares the absolute value of the phase error (Δφn) with π / 2. The phase difference correction circuit 51 reduces the phase error to 0 if the absolute value is π / 2 or more.
(Δφn ′ = 0), otherwise, the original value of the phase error is output as it is (Δφn ′ = Δφn). Even if the signal phase inversion (FIG. 3) caused by the unique word (FIG. 5) periodically inserted in the pilot signal occurs by the phase difference determination and correction processing, it is forced to 0. It is possible to completely prevent the malfunction of the loop filter. The phase difference correction 51 corrects the phase error by 180 when the absolute value of the phase error is π / 2 or more.
Inversion (if Δφn> 0, Δφn ′ = Δφn−180
Degree, otherwise Δφn ′ = Δφn + 180 degrees),
Otherwise, the original value of the phase error may be output as it is (Δφn ′ = Δφn). Even in this case, the same effect as the above can be obtained. In this case, the reference signal 4 (FIG. 2) is equivalently one in which a unique word is inserted every frame period, which has an advantage that the PLL process can be effectively performed on all data.

On the other hand, in the asynchronous state, the switch control unit 11 connects the switch to the side a and inputs the phase error (Δφn) to the phase difference correction circuit 5. In this case, the phase difference determination process is not performed, and the normal pull-in process is performed until the synchronized state is achieved. That is, the process when the switch is connected to the a side is the same as the conventional process.

The phase difference correction circuit 5 performs correction for preventing reverse control of the PLL. Specifically, as shown in FIG. 7, the value of the phase difference is always set to the same sign depending on the phase rotation direction (positive or negative). by this,
It is possible to make the phase control direction of the PLL the same and prevent reverse control. For example, if the phase is rotating in the positive direction, Δφn
Is in the range of 0 to 2π, and Δφ when rotating in the negative direction.
n should be in the range of 0 to −2π.

The phase error Δφn ′ corrected by the phase difference correction circuit 5 or 51 is input to the loop filter 6. The loop filter 6 is a low-pass filter for noise removal that is used in a normal well-known second-order PLL, and a detailed description thereof will be omitted. However, the loop filter 6 is not necessary for abrupt phase change caused by noise or the like. P not to follow
It is for adjusting the response speed of LL. The loop filter output is integrated by the VCO 7 to obtain the phase rotation amount φn.

The sine wave generator 8 is for generating COSφn and SINφn according to the phase rotation amount φn. These signals are used to correct the phase of the despread output of the received pilot signal, as described above. This phase correction is also made on the data despread output of the traffic channel signal. In spread spectrum communication, data is always multiplexed in synchronization with a pilot signal, so that the phase of data can be known by knowing the phase of pilot. Therefore, if the pilot signal is synchronized, the data signal can be easily demodulated in the same phase. The traffic channel output after the phase correction is demodulated at the timing of the frame head detection signal in the data demodulation unit 9 and restored to the received data.

Next, the synchronization state monitoring unit (see FIG. 6) in the present invention will be described.

As described above, the synchronization state monitoring unit constantly monitors the value of the phase error Δφn, estimates the synchronization rate based on the value, and synchronizes if the synchronization rate is equal to or less than the preset allowable value. On the contrary, when the synchronization rate is continuously larger than the allowable value for a fixed monitoring period, it is determined to be the asynchronous state.

FIG. 8 shows the specific algorithm. After inputting the phase difference Δφn, it is determined whether or not the absolute value is larger than π / 2.
The input value of (LowPass Filter) is set to "1", and if not, the input value of LPF is set to "0".

Here, the averaging LPF is a well-known first-order digital filter as shown in FIG.
It is composed of a multiplier 81, an adder 82, and a delay element 83.
α represents a gain that determines the response speed of the filter.

By the above operation, for example, when Δφn becomes abnormally large without the PLL being synchronized, the LPF output X
, The average value increases with time (it can be estimated that the synchronization rate is small). LPF when PLL is synchronized
The output will stay near 0 on average (it can be estimated that the synchronization rate is high). Therefore, when the LPF output value X is equal to or less than the allowable value X0 (X0> 0), the synchronization rate is sufficiently high and P
When it is determined that the LL is in the synchronization state, the value of the counter provided in the synchronization state monitoring unit is reset to 0, and the switching control in the synchronization state is performed (the switch in FIG. 1 is connected to the side a).

On the other hand, when X> X0, the synchronization rate is low,
Since it is highly possible that the PLL is asynchronous, it is observed using a pulse counter whether this state continues for a certain period or longer. That is, if X> X0, the counter value i is incremented by "1" by counting up, and it is determined whether or not the count result is longer than the observation period M (bits). If the counter value i is larger than M, it is determined that the state is asynchronous,
The switch (FIG. 1) is connected to the a side by switching control.

With the above processing, according to the present invention, it is possible to automatically observe the synchronous / asynchronous state in the device.
The values of X0 and M are determined as follows, for example.

In the asynchronous state, the decoding error rate is statistically 0.
It becomes 5, and it is considered that it is unknown whether it is “1” or “0”.
Therefore, it is judged that there is a high possibility that the value exceeding half of this value, that is, 0.25, is asynchronous, and X0 =
It is set to 0.25. Also, the parameter α of the averaging LPF =
It is set to 0.98. This corresponds to a time constant of 1.59 ms (about 50 bits) at 32 kHz sampling. This requires at least 1 / 0.25 = 4 bits of averaging time. On the other hand, for M, the following equation is satisfied.

[0047]

[Equation 1]

Here, the expected value of the LPF input when the unique word arrives is set to 0.5. N = 0 to 31 corresponds to 32 bits of the unique word.

According to the configuration of the above embodiment, the phase difference determination process is not performed until the synchronization state is determined in the initial PLL pull-in process, so that even if the PLL pull-in is completed,
When the unique word is received, the LPF input is disturbed. Therefore, if the LPF output after observing only M from this point becomes sufficiently smaller than 0.25, it may be determined that the PLL is synchronized. This is over the observation period M
When the LPF output exceeds 0.25, it means that it can be determined that the asynchronous state. The value of M is 50, for example. It can be easily confirmed that M = 50 sufficiently satisfies the above formula.

9 and 10 show simulation results of the phase pull-in characteristic of the PLL according to the present invention. Each figure shows the time transition of the PLL phase control error when the response speed (rise time) of the PLL is 0.17 ms and 2 ms, respectively, and the upper side shows the characteristics of the conventional method and the lower side shows the characteristics of the present invention method. There is. Here, Δf = 5 kHz is assumed as the frequency offset. PLL
The phase control error (unit: rad) is the VCO in FIG.
It is the difference between the output and its theoretical value. Data rate is 32k
One frame (= 960 bits) corresponds to 30 ms. Further, it is assumed that the data is received from the beginning (unique word) of the frame at time 0.

As is clear from the figure, in the conventional system, P
It can be seen that a large phase variation occurs when the unique word is re-received after the LL pull-in (from the 961th bit onward), and the characteristics of the PLL are significantly deteriorated. On the other hand, in the method of the present invention, even if a unique word is received at the same time, it is not affected by the phase fluctuation, and there is no malfunction of the PLL at all. This is because abnormally large phase fluctuations are removed by the synchronization state monitoring means and the phase difference determination means.

In the conventional system, the influence of the phase fluctuation is reduced by slowing the response speed of the PLL, but as can be seen from FIG. 10, even if the rise time is slowed,
It is not possible to completely eliminate the influence of the phase fluctuation caused by the unique word. On the other hand, according to the method of the present invention, the PLL operates normally without being affected by the phase fluctuation even when the unique word arrives.

In the above description, the quasi-synchronous detection demodulation, that is, the method of compensating for the deviation by the baseband processing of the receiving unit when the carrier frequency and the phase between transmission and reception are slightly different is assumed. The present invention can also be applied to synchronous detection demodulation, that is, a method of compensating carrier frequency and phase shift between transmission and reception in a carrier band.

[0054]

As is apparent from the above description, according to the present invention, the base station only needs to insert the unique word only in the pilot channel and does not need to provide the synchronization channel, so that the throughput of the traffic channel can be improved. Can be improved. In addition, in the mobile station, the receiver unit performs frame synchronization by using a pilot channel output at a transmission power (usually about 10 dB or more) higher than that of the traffic channel.
Data can be demodulated with N.

Further, by providing the quasi-synchronous detection demodulator with a synchronization state monitoring means, a switching control means and a phase error determination means, the synchronous / asynchronous state is automatically observed, and an appropriate position according to the state is detected. It is possible to switch to the phase difference correction process. Further, even if the pilot signal includes data (unique word) in which the phase changes irregularly, it is possible to eliminate the influence of a large phase variation due to it and prevent the malfunction of the PLL.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a CDMA mobile communication system.

FIG. 2 is a diagram showing a configuration of a base station transmitter and a mobile station receiver in a conventional CDMA modulator / demodulator.

FIG. 3 is a diagram showing an example of a frame configuration of a pilot signal. ,

FIG. 4 is a diagram showing an example of signal point arrangement and reception points by QPSK modulation.

FIG. 5 is a diagram showing a configuration of a base station transmission unit and a mobile station reception unit in the CDMA mobile communication system of the present invention.

FIG. 6 is a diagram showing a configuration of a quasi-coherent detection demodulator according to the present invention.

FIG. 7 is a diagram for explaining phase difference correction for preventing reverse phase control by a PLL.

FIG. 8 is an explanatory diagram of a synchronization status monitoring unit.

FIG. 9 is a diagram showing an example of a simulation result of PLL pull-in characteristics in the quasi-coherent detection demodulator.

FIG. 10 is a diagram showing another example of the simulation result of the PLL pull-in characteristic in the quasi-coherent detection demodulator.

[Explanation of symbols]

1 ... Phase correction unit, 2 ... Amplitude normalization unit, 3 ... Phase difference calculation unit, 4 ... Reference signal, 5 ... Phase difference correction 1, 51 ... Phase difference correction 2, 6 ... Loop filter, 7 ... VCO, 8 ... Sine wave generator, 9 ... Data demodulator, 10 ... Sync state monitor, 11
... Switching control unit, 12 ... Phase difference determination unit, 11-13 ... Base station, 14-16 ... Cell, 17 ... Wireless line control station, 21 ...
Pilot data generation unit, 22 ... Phase modulation unit, 23 ... Spread spectrum unit, 24 ... Multiplexing unit, 25 ... Synchronization channel data generation unit, 26 ... Unique word insertion unit, 27 ... Mobile station addressed data generation unit, 28 ... Carrier Modulation unit, 29 ... Base station antenna, 30 ... Mobile station antenna, 31 ... Carrier demodulation unit, 32 ... Spectrum despreading unit, 33, 33a ... Quasi-synchronous detection demodulation unit, 34 ... Frame synchronization unit, 81 ... Multiplier, 82 ... Adder, 83 ... Delay element, 101-106 ...
Mobile station.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location 9297-5K H04L 27/22 D

Claims (4)

[Claims] 1. A base station periodically inserts a frame synchronization signal into a pilot channel, spreads the pilot channel signal and the traffic channel signal addressed to each mobile station, respectively, and sends the signals to the air. A CDMA mobile communication system, wherein a mobile station extracts a frame synchronization signal from a pilot channel reception signal and demodulates data from a traffic channel reception signal based on the frame synchronization signal. 2. A means for generating a pilot signal in which a unique word is inserted every frame period, a means for phase modulating the pilot signal, and data for a plurality of mobile stations synchronized with the phase modulated pilot signal. And means for phase modulating, means for spreading the spectrum of the phase modulated pilot signal and data respectively, means for multiplexing the plurality of spread spectrum signals, and carrier-modulating the multiplexed output for transmission. A base station apparatus for a CDMA mobile communication system, comprising: 3. A means for demodulating a received spread spectrum signal by a carrier, a means for despreading the demodulated output as a pilot signal and a data signal, and a despread pilot signal and a data signal, respectively. A receiver is provided that includes means for correcting the phase, means for performing frame synchronization and quasi-synchronous detection on the pilot signal after the phase correction, and means for demodulating the data after the phase correction in synchronization with the pilot signal. A mobile station of a CDMA mobile communication system. 4. The receiving unit detects a frame head from the phase-corrected pilot signal, demodulates the phase-corrected data signal at an output timing of a frame head detection signal, and Means for normalizing the amplitude of the pilot output after phase correction, means for calculating the phase difference between the normalized pilot signal and the reference signal, and monitoring the phase synchronization state based on the magnitude of the phase difference Means, means for performing signal switching control in a synchronous state or an asynchronous state, means for correcting a phase difference according to the output of the switching control means, and a loop filter for removing a noise component of the corrected phase difference, The phase correction means includes means for integrating the loop filter output and means for generating a sine wave having a phase corresponding to the integration result, and the phase correcting means uses the sine wave to generate a pilot signal. Mobile station of a CDMA mobile communication system according to claim 3, characterized in that the rotation correction phase.