JPH08116303A - Spread spectrum radio communication system and radio communication equipment for base station and radio communication equipment for mobile station used in the same - Google Patents

Abstract

PURPOSE: To always set S/N at a high level and to perform reception with small transmission error by setting the optimum pass length on the RAKE receiver of a reception station even when radio environment changes. CONSTITUTION: In the base station, the radio transmission characteristic of a forward link is measured from the reception electric field intensity of a radio signal arriving from a mobile station via a reverse link by a radio transmission line measuring part 18b. Information representing the optimum pass length to be set on the RAKE receiver of the mobile station is generated based on a measured result, and such optimum pass length information is given to the mobile station via the forward link. While, in the mobile station, the optimum pass length information is sampled by a pass length information sampling part, and the number of taps of the transversal filter of the RAKE receiver is set based on the optimum pass length information.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile radio communication system such as an automobile / portable radio telephone system, a cordless telephone system, a wireless LAN system, etc., and particularly to a system to which a spread spectrum communication system is applied and used in this system. The present invention relates to a base station wireless communication device and a mobile station wireless communication device.

[0002]

2. Description of the Related Art In recent years, a spread spectrum communication system, which is resistant to interference and interference, has attracted attention as one of communication systems applied to mobile radio communication systems. Spread spectrum communication system is based on Code Division Multiple Access (CDMA).
This is realized by, for example, a device on the transmission side, after modulating the digitized voice data or image data by a digital modulation system such as a PSK or FSK modulation system. The transmission data is converted into a wideband baseband signal by using a spread code such as a pseudo noise code, and then converted into a radio channel frequency signal for transmission.
On the other hand, in the receiving side device, after performing frequency conversion of the received radio channel frequency signal into a signal of an intermediate frequency or a baseband frequency, despreading is performed using the same code as the spreading code used in the transmitting side device. After that, the digital data is demodulated by a digital demodulation system such as a PSK or FSK demodulation system to reproduce the received data.

By the way, in this type of system, a RAKE receiver is used as one of countermeasures against fading and multipath. RAKE means a rake, and scrapes signals scattered over time to perform time diversity. The RAKE receiver connects a transversal filter with taps to the output of a matched filter, adds a pulse train output from the matched filter by changing the weighting of the tap coefficient, and performs multipath synthesis. It is well known that a plurality of finger circuits each including a tracking loop and a data demodulation unit are provided, and these finger circuits are independently operated to perform multipath combining.

Of these, for example, when a transversal filter type RAKE receiver is used, the energy of the multipath signal is effectively added by setting an appropriate tap coefficient for each tap of the transversal filter.
As a result, the S / N ratio of the receiver can be improved and the transmission error rate can be reduced. That is, in order to operate the RAKE receiver effectively, it is important how to set the tap coefficient to an appropriate value.

Therefore, conventionally, for example, a transmitting station inserts a surrounding signal as a transmission line measuring signal into a communication signal for transmission, and the receiving station receives this surrounding signal and changes the state of the transmission line from the reception state thereof. Has been proposed, and a method of setting the optimum tap coefficient based on this measured value has been proposed. However, in order to accurately measure the state of the transmission path, the surrounding signal must be transmitted for a certain length of time, which results in deterioration of communication efficiency and complication of the communication protocol, which is not preferable.

On the other hand, as another method for setting the optimum tap coefficient, a method of numerically estimating a wireless channel model affected by multipath from a received signal not including a surrounding signal has been studied. ing. As an algorithm for estimation, for example, a method using a least square method, a learning identification method, or a Kalman filter is used. With this method, it is not necessary to transmit a surrounding signal, so that communication efficiency is improved.

However, in such a system, the synthetic path length, that is, the number of paths of the transversal filter is fixedly set to a predetermined maximum value. For this reason, when communication is performed in a wireless environment where the state of the wireless transmission path is poor and there are many multipaths, such as in an urban area where there are many buildings, the multipaths are added without fail by combining many paths. Therefore, the S / N ratio is increased and the error rate is decreased, which is extremely effective. However, when communicating in a wireless environment where the state of the wireless transmission path is relatively good and there are few multipaths, such as in a suburb with good visibility, if there are many paths, there will be many paths that only add noise. , Warped S
This is not preferable because it causes deterioration of / N and an increase in error rate.

[0008]

As described above, in the tap coefficient setting method that has been conventionally studied, the path length is set to a predetermined maximum value without considering the change in the state of the wireless transmission path at all. It is fixed. Therefore, there is a problem in that the S / N is lowered and the error rate is increased in a warped state when the state of the wireless transmission path is relatively good.

The present invention has been made in view of the above circumstances, and a first object thereof is to set an optimum path length for a RAKE receiver of a receiving station even if the radio environment changes. As a result, a spread spectrum wireless communication system that can always perform high quality reception with a high S / N and less transmission errors, and a base station wireless communication apparatus and a mobile station wireless communication apparatus used in this system are provided. Especially.

A second object is that even if the radio environment changes, the RAKE receiver of the receiving station can operate an optimum number of finger circuits, and thus the S / N ratio is always maintained.
(EN) Provided are a spread spectrum wireless communication system capable of high quality reception with less transmission error, a base station wireless communication apparatus and a mobile station wireless communication apparatus used in this system.

[0011]

In order to achieve the above first object, a spread spectrum wireless communication system of the present invention is a measurement for measuring a state of a wireless transmission path between a base station and a mobile station. Means and a path length information notifying means,
The path length information notifying means determines the optimum path length based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum path length. On the other hand, the mobile station is provided with tap control means, and the tap control means variably sets the number of taps of the transversal filter of the RAKE receiver according to the optimum path length information notified from the base station. is there.

Also, in the system of the present invention, the tap control means variably sets the number of taps of the transversal filter to be operated according to the optimum path length information notified from the base station, and the taps set in this operating state. Is characterized in that the state of the wireless transmission path is estimated and the tap coefficient of is adaptively variably controlled based on the estimation result.

In order to achieve the above second object, the spread spectrum wireless communication system of the present invention provides a base station with a measuring means for measuring the state of a wireless transmission path to a mobile station and a finger information notification. Means for determining the optimum number of fingers on the basis of the measurement result of the measuring means, and notifying the mobile station of information indicating the optimum number of fingers. On the other hand, the mobile station is provided with finger control means, and this finger control means selectively operates a plurality of finger circuits of the RAKE receiver according to the optimum finger information notified from the base station.

In order to achieve the above first object, the base station radio communication apparatus of the present invention comprises a measuring means for measuring the state of a radio transmission path with a mobile station, and a path length information notifying means. Is equipped with. Then, the path length information notifying means obtains the optimum path length based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum path length, and the RAKE receiver of the RAKE receiver according to the optimum path length information. The number of taps of the transversal filter is variably set.

In order to achieve the above second object, the base station radio communication apparatus of the present invention comprises a measuring means for measuring the state of a radio transmission path with a mobile station and a finger information notifying means. I have it. Then, the finger information notifying means obtains the optimum number of fingers based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum number of fingers, and the RAKE receiver according to the optimum finger number information. The above-mentioned finger circuits are selectively operated.

In order to achieve the first object, the mobile station radio communication apparatus of the present invention is a transversal filter that synthesizes a plurality of identical transmission signals received with a time difference and reproduces the transmission signals. And a tap control means. The tap control means variably sets the tap number of the transversal filter of the RAKE receiver according to the optimum path length information notified from the base station.

In order to achieve the second object, the mobile station radio communication apparatus of the present invention combines a plurality of identical transmission signals received with a time difference and reproduces the transmission signals. It is provided with a RAKE receiver having a finger circuit and finger control means. Then, the finger control means selectively operates the plurality of finger circuits of the RAKE receiver according to the optimum finger number information notified from the base station.

[0018]

As a result, according to the spread spectrum wireless communication system, the base station wireless communication apparatus, and the mobile station wireless communication apparatus of the present invention, when the mobile station uses the transversal filter type RAKE receiver, When the state of the wireless transmission path changes, the base station creates optimal path length information according to this state change and notifies the mobile station, and the mobile station responds to this optimal path length information and determines the number of taps of the transversal filter. Is controlled. Therefore, when wireless communication is performed in locations such as urban areas, suburbs, and indoors where the wireless propagation environments are different, it is possible to set a path length that is suitable for the wireless propagation environments in these locations. It is possible to perform wireless communication with good / N and few transmission errors.

Further, the tap control means adaptively variably controls the tap coefficient of the path set to the operating state by the optimum path length information according to the state of the wireless transmission path. That is, a large change in the state of the wireless transmission line can be handled by variably setting the path length, that is, the number of taps, and a small change in the wireless transmission line can be adjusted by adjusting the tap coefficient according to the state of the wireless transmission line. It can be dealt with by controlling it dynamically. Therefore, it is possible to perform wireless communication so that the S / N is always the best and the transmission error is the minimum.

On the other hand, according to the spread spectrum wireless communication system, the base station wireless communication device and the mobile station wireless communication device of the present invention, when the mobile station uses a RAKE receiver having a plurality of finger circuits. , When the state of the wireless transmission path changes, information about the optimum number of fingers according to the change in this state is created in the base station and notified to the mobile station,
In the mobile station, a plurality of finger circuits are selectively set in the operating state according to the optimum finger information. Therefore, when wireless communication is performed in locations where the wireless propagation environment is different, such as in urban areas, suburbs, and indoors, reception can be performed with the number of fingers suitable for the wireless propagation environment in these locations. As in the first aspect of the invention, it is possible to always perform wireless communication with a good S / N and few transmission errors.

[0021]

An embodiment of the present invention will be described below with reference to the drawings. In this embodiment, the base station measures the state of the wireless transmission path based on the reception state of the transmission data that has arrived from the mobile station via the reverse link of the wireless transmission path, and obtains the optimum path length from the measurement result. This optimum path length information is transmitted to the mobile station via the forward link of the wireless transmission path. Then, in the mobile station, RA is performed according to the optimum path length information.
The number of operation taps of the transversal filter of the KE receiver is variably set.

FIG. 1 is a schematic configuration diagram of a cellular mobile communication system according to this embodiment. This system includes a control station CS, a plurality of base stations BS1, BS2, ... And a plurality of mobile stations MS1, MS2 ,. Control station CS
Are connected to the wired telephone network NW via the wired line group CL. The base stations BS1, BS2, ... Are connected to the control station CS via wired lines CL1, CL2 ,. Also, each base station BS1, BS2, ...
The wireless zones E1, E2, ... Each called a cell are formed. A plurality of radio frequencies are assigned to these radio zones E1, E2, ..., At least so that radio frequencies are different between adjacent radio zones.

In the system of this embodiment, the base stations BS1,
Between the BS2, ... and the mobile stations MS1, MS2, ..., a code division multiple access (CDMA) method using spread spectrum is adopted as an access method, and time division multiplexing (signal division method) is adopted. TD
D: Time Division Duplex) method is used for wireless communication.

That is, at the time of communication, the base stations BS1 and BS
, And each mobile station MS1, MS2, ... Between the radio frequencies f1 used for transmitting call voice data.
Is set. The transmission format of the signal transmitted by the radio frequency f1 is, for example, as shown in FIG. 3, three slots FL1 to F for the forward link in one frame.
L3 and three slots for reverse link RL1 to RL
3 and 3 are arranged alternately. That is, in the system of this embodiment, the forward link and the reverse link are set on the common radio frequency f1.

FIG. 2 is a circuit block diagram showing a main configuration of the base stations BS1, BS2, .... In the figure,
Radio signals transmitted from mobile stations MS1, MS2, ... (not shown) are received by an antenna 11 and then input to mixers 13I, 13Q via an antenna duplexer (DUP) 12. In these mixers 13I and 13Q, the received radio signal is mixed with two local oscillation signals having a phase difference of π / 2 and frequency-converted into a baseband signal. Note that the local oscillation signal is the local oscillator 14
Of the oscillation output fc of
It is generated by shifting the phase with the two-phase shifter 15. The received baseband signals output from the mixers 13I and 13Q are low pass filters (LPF) 16I and 16Q to remove unnecessary harmonic components, and then the matched filter 17 is used.
Is input to When the received baseband signal is input, the matched filter 17 outputs a pulse train having a plurality of peak trains according to the arrival time and the signal strength as shown in FIG. 6, and the pulse train is the RAKE receiver 18. Entered in.

The RAKE receiver 18 is a RAKE receiver 1
8a and a wireless transmission line measuring unit 18b. RA
The KE receiving unit 18a uses the spread code rate (chip rate).
It is composed of transversal filters with taps arranged at the reciprocal time intervals of. That is, the pulse train output from the matched filter 17 is delayed by the delay line so that the time interval is the reciprocal of the spread code rate, and then input to each tap. Then, after the tap coefficients are weighted at these taps, they are mutually added by an adder and output as received data.

The wireless transmission line measuring unit 18b measures the transmission characteristic of the wireless transmission line on the forward link based on the received electric field strength of the wireless signal that has arrived from the mobile station of the communication partner via the reverse link. Then, this measurement signal is transferred to the control circuit 19.

The control circuit 19 has a path length information notification control means 19a in addition to a normal control function required for communication with a mobile station such as radio channel connection control and call control. The path length information notification control means 19a obtains the optimum path length based on the measurement signal transferred from the wireless transmission path measuring unit 18b, and the transmission data generating unit 21 notifies the mobile station of the optimum path length information. Transfer to. The transmission data generation unit 21 adds the above-mentioned optimum path length information to the control signal to generate slot transmission data, as shown in FIG. 3, and inserts this slot transmission data into the transmission slot FL2 of the forward link to form a modulation circuit ( MOD) 22.

The modulation circuit 22 digitally modulates the transmission data of the transmission slot, and then the spreading code generator 23.
Spread spectrum modulation is performed by the spread code generated from the signal and converted into a wide band transmission signal. FIG. 4 shows an example of the configuration of the spread code generator 23. The spread code generator 23 includes a five-stage configuration shift register 231 and
It is composed of a tap group 232 and an adder group 233, and appropriately disconnects the state of each tap of the tap group 232 (hi =
0) or connected (hi = 1), the shift register 231 outputs the M-sequence spreading code.

For example, as shown in FIG. 11, the tap coefficients are (h1, h2, h3, h4, h5) = (1,
1, 0, 1, 1) and each register R1, R2, R3, R4, R5 of the shift register 231 has an initial value (s).
1, s2, s3, s4, s5) = (1,1,0,0,
Give 1). By doing so, the required spreading code can be generated.

The transmitter 24 converts the transmission signal output from the modulation circuit 22 into a predetermined radio frequency signal f1 and then amplifies the power to a predetermined transmission power level. Then, this radio frequency signal is supplied to the antenna 11 via the antenna duplexer 12, and is thereby transmitted to the mobile station MS.

On the other hand, the mobile stations MS1, MS2, ... Are constructed as follows. FIG. 5 is a functional block diagram showing the main configuration of the receiving system. In the figure, the base station BS
The radio frequency signal arriving from is received by the antenna 31, then branched into two, and input to the mixers 32I and 32Q. In these mixers 32I and 32Q, the received radio signal is mixed with two local oscillation signals having a phase difference of π / 2 and frequency-converted into a baseband signal. The local oscillation signal is generated by bifurcating the oscillation output fc of the local oscillator 33 and then phase-shifting one of them by the π / 2 phase shifter 34. The mixer 32
The reception baseband signals output from I and 32Q are input to the matched filter 36 after unnecessary harmonic components are removed by low pass filters (LPF) 35I and 35Q. When the received baseband signal is input, the matched filter 36 outputs a pulse train having a plurality of peak trains according to the arrival time and the signal strength.

FIG. 6 shows an example of the structure of the matched filter 36. The matched filter 36 has a delay line 361 that delays a received baseband signal.
, A multiplier 362, and a low-pass filter 363.
Composed of and. The same spreading code as the spreading code used by the base station BS for transmission is set and input to the multiplier 362 at the chip rate, and a large level is set at the timing when the spreading code and the received baseband signal match. A pulse is output. For simplicity of explanation, in FIG. 6, the code length of the spreading code is set to 7, and the spreading code is set to (+
1, -1, +1, +1, -1, -1, -1) is input to the multiplier 362. In this example, a level +7 pulse is output as shown in FIG. 7 at the timing when the received baseband signal matches the spread code.

The RAKE receiver 37 is the RA of the base station.
Like the KE receiver 18a, it has a transversal filter with taps arranged at time intervals which are the reciprocal of the spread code rate (chip rate). When the pulse train output from the matched filter 36 is input, the pulse train is delayed by a delay line so as to have a time interval that is the reciprocal of the spread code rate, and then tap coefficients are weighted at the taps. Then, the values are added together and the level is determined, and then output as received data.

The received data is input to a codec (not shown) for the decoding process and also input to the path length information extraction unit 38. The path length information extraction unit 38 extracts optimum path length information from the received data. Then, the extracted optimum path length information is supplied to the RAKE receiver 37 in order to variably set the number of taps of the transversal filter of the RAKE receiver 37.

By the way, the RAKE receiver 37 is constructed as follows. FIG. 8 is a circuit block diagram showing the configuration. The RAKE receiver 37 has a delay line 37
1, a transversal filter with taps including a tap group 372 and an adder 373, and a reception data determination unit 3
74, a parameter adaptation setting unit 375, and a subtractor 376.
Composed of and.

First of all, the reception data judging section 374
The output signal of the transversal filter is level-determined at an appropriate data reception timing, and this determination output is output as reception data. The subtractor 376 subtracts the output signal of the transversal filter from the received data and outputs an error signal.

The parameter adaptive setting unit 375 has a first control function for variably setting the number of taps of the transversal filter and a second control function for adaptively variably controlling the tap coefficient. The first control function sets the number of taps for the transversal filter according to the optimum path length information supplied from the path length information extraction unit 38. On the other hand, the second control function is the output signal of the delay line 371 of the transversal filter,
From the error signal output from the subtractor 376, the state of the wireless transmission path is estimated using an estimation algorithm such as a least squares method, a learning identification method, or a Kalman filter,
Based on this estimation result, the optimum tap coefficient is set for the tap set by the first control function.

Next, the operation of the system configured as described above will be described. When a radio link is set up with the mobile station MS, the base station BS arrives from the mobile station MS via the reverse link RL in the radio transmission path measurement unit 18b of the RAKE receiver 18 before transmitting / receiving the call data. Forward link FL from the received electric field strength of the received wireless signal
The wireless transmission characteristics of are measured. Then, according to the measured characteristic, information representing the optimum number of taps to be set in the transversal filter of the RAKE receiver 37 of the mobile station MS is generated. The optimum tap number information is added to the control signal in the transmission data generation unit 21 as shown in FIG. 3 according to the instruction of the control circuit 19, and then transmitted to the mobile station MS via the forward link FL.
Incidentally, FIG. 3 shows a case where “4” is transmitted as the optimum tap number information.

On the other hand, in the mobile station MS, the parameter adaptation setting unit 375 in the RAKE receiver 37 responds to the tap corresponding to the predetermined path length (for example, “8”) among all the taps 372 of the transversal filter. ,
First, all 0s or all 1s are initialized. And
In this state, the parameter adaptive setting unit 375 estimates the state of the wireless transmission path based on the output signal of the delay line 371 and the error signal, and determines the tap coefficient of the tap based on the estimation result.

Now, assume that the optimum path length information arrives from the base station BS in this state, and the optimum path length information is extracted by the path length information extraction unit 38. Then, the parameter adaptation setting unit 375 changes and sets the number of taps of the transversal filter according to the optimum path length information. For example,
As described above, assuming that the optimum path length information “4” has arrived, the number of taps of the transversal filter is calculated from the number of taps corresponding to the path length “8” that has been set until then. The number of taps corresponding to “4” is changed and set.

FIG. 9 shows the setting state of the taps of the transversal filter after this change setting. With this configuration, when four multipath received signals appear in the output pulse train of the matched filter 36 at a certain time interval as shown in FIG. 9A, these four multipath received signals are most efficiently used. The transmission data can be reproduced by well performing addition synthesis.

Even after the setting of the number of taps is changed, the parameter adaptive setting unit 375 operates the delay line 37.
The state of the wireless transmission path is estimated based on the output signal of 1 and the error signal. Then, based on this estimation result, a control operation for adaptively controlling the tap coefficient of each tap after the change setting is performed.

As described above, in the system of the present embodiment, in the base station BS, the wireless transmission path measuring unit 18b performs wireless transmission of the forward link FL from the received electric field strength of the wireless signal arriving from the mobile station MS via the reverse link RL. The characteristics are measured, and the RAK of the mobile station MS is based on this measurement result.
Information indicating the optimum path length to be set in the E receiver 37 is created, and the optimum path length information is notified to the mobile station MS via the forward link FL. On the other hand, in the mobile station MS, the optimum path length information is extracted by the path length information extraction unit 38, and the number of taps of the transversal filter of the RAKE receiver 37 is set based on the optimum path length information.

Therefore, according to the present embodiment, in a wireless environment in which the state of the wireless transmission path is poor and multipaths are likely to occur frequently, such as in an urban area, the path length of the RAKE receiver of the mobile station can be set long. On the other hand, in a wireless environment where the state of the wireless transmission path is relatively good and there are few multipaths such as in the suburbs, the path length of the RAKE receiver of the mobile station can be set short. That is, the optimum path length can be set according to the state of the wireless transmission path. Therefore, it is possible to perform high-quality wireless communication with a good S / N and a small transmission error rate regardless of the difference in wireless environment.

Further, in the present embodiment, as described above, the difference in wireless environment is dealt with by variably setting the path length, while the change of the wireless transmission path during the communication corresponds to the state of the wireless transmission path. This is dealt with by adaptively controlling the tap coefficient according to.

Therefore, according to the present embodiment, even when the radio environment is different or the state of the radio transmission path is changed during the radio communication, the S / N is always good and the radio quality is high and the transmission error rate is small. Can communicate.

Next, another embodiment of the present invention will be described. In this embodiment, the RA using the finger circuit in the mobile station is used.
When the KE receiver is used, the state of the wireless transmission line is measured based on the reception state of the transmission data that arrives from the mobile station via the reverse link of the wireless transmission line at the base station, and the optimum finger is obtained from this measurement result. Then, the optimum finger number information is transmitted to the mobile station via the forward link of the wireless transmission path. Then, in the mobile station, a plurality of finger circuits of the RAKE receiver are selectively operated according to the optimum finger number information.

FIG. 10 is a circuit block diagram showing a main configuration of a receiving system in a mobile station of the wireless communication system according to this embodiment. In the figure, a radio frequency signal received by an antenna 71 is mixed with a local oscillation signal by a high frequency demodulation circuit 72 and converted into an intermediate frequency or base band signal, and then a plurality of finger circuits 731, 73.
2, ..., 73n, respectively. Each of the finger circuits 731, 732, ..., 73n has a timing tracking loop and a data demodulation unit, and operates independently of each other.

These finger circuits 731, 732,
, 73n are input to the symbol combiner 75, and the symbol combiner 75 combines the symbols to reproduce the received data. This received data is output to a codec (not shown) for data decoding processing, and is also input to the finger information extraction unit 74. The finger information extraction unit 74 extracts optimum finger number information from the received data and determines a finger circuit to be operated according to this optimum finger number information.

Next, the operation of the system configured as described above will be described. The base station BS will be described with reference to FIG. When a radio link is set up with the mobile station MS, the base station BS arrives from the mobile station MS via the reverse link RL in the radio transmission path measurement unit 18b of the RAKE receiver 18 before transmitting / receiving the call data. Forward link FL from the received electric field strength of the received wireless signal
The wireless transmission characteristics of are measured. Then, information representing the optimum number of fingers to be assigned to the mobile station MS is generated according to the measured characteristic. This optimum finger number information is transmitted to the transmission data generation unit 2 according to the instruction of the control circuit 19.
1 is added to the control signal and then transmitted to the mobile station MS via the forward link FL.

On the other hand, in the mobile station MS, when the optimum finger number information arrives from the base station BS, this information is extracted by the finger information extracting section 74 having a function as a searcher. Then, the finger information extraction unit 74 causes the plurality of finger circuits 731 to 731 to correspond to the optimum finger number information.
It is determined which finger circuit of 73n is to be operated, and an operation control signal is given to each finger circuit. For example, if the optimum finger number information "16" has arrived, 16 finger circuits are set to the operating state. Therefore, in this case, even if the quality of the wireless transmission path is poor and a large number of multipaths are generated, these multipaths can be efficiently received and reproduced by the above-mentioned finger circuits and combined by the symbol combiner 75. .

On the other hand, if "4" has arrived as the optimum finger number information, the four finger circuits are set to the operating state. Therefore, in this case, when the quality of the wireless transmission path is relatively good and the number of multipaths generated is small, it is possible to prevent a problem that noise is unnecessarily reproduced and synthesized, thereby keeping the S / N high. be able to.

The present invention is not limited to the above embodiments. For example, the optimum path length information and the optimum number of fingers are notified from the base station to the mobile station after the wireless link is formed but before the communication starts. The path length information and the optimum finger number information may be generated and notified to the mobile station. After the initial setting of the tap coefficient, the base station constantly monitors the transmission characteristics of the wireless transmission path, and notifies the mobile station of the optimum path length information and the optimum finger number information when the transmission characteristics change by a predetermined amount or more. May be.

Further, in the above-described embodiment, the case where the present invention is applied to the system (TDD system) in which the forward link and the reverse link are set on the same radio frequency has been described. However, when the frequency selective fading is less likely to occur. In addition, the present invention may be applied to a system in which the forward link and the reverse link are set on different radio frequencies.

In addition, the present invention also describes the types of radio communication systems, the configurations of base stations and mobile stations, the notification means of the optimum path length information and the optimum finger number information, and the procedure for setting the path length and the number of fingers in the mobile station. Various modifications can be implemented without departing from the scope of the invention.

[0057]

As described in detail above, in the spread spectrum radio communication system of the present invention, the base station measures the state of the radio transmission path with the mobile station and the path length information notifying means. The path length information notifying means determines the optimum path length based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum path length. On the other hand, the mobile station is provided with tap control means, and the tap control means variably sets the number of taps of the transversal filter of the RAKE receiver according to the optimum path length information notified from the base station.

Therefore, according to the present invention, even if the radio environment changes, it is possible to set the optimum path length for the RAKE receiver of the receiving station, so that the S / N is always high and the transmission error is small. A spread spectrum wireless communication system that can perform quality reception can be provided.

Further, in the spread spectrum radio communication system of the present invention, the base station is provided with a measuring means for measuring the state of the radio transmission path with the mobile station and a finger information notifying means. The notification means obtains the optimum number of fingers based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum number of fingers. On the other hand, the mobile station is provided with finger control means, and this finger control means selectively operates a plurality of finger circuits of the RAKE receiver in accordance with the optimum finger information notified from the base station.

Therefore, according to the present invention, even if the radio environment changes, it is possible to operate the optimum number of finger circuits in the RAKE receiver of the mobile station, whereby the S / N is always high and the transmission error does not occur. It is possible to provide a spread spectrum wireless communication system capable of performing low quality reception.

Furthermore, the base station radio communication apparatus of the present invention comprises a measuring means for measuring the state of the radio transmission path with the mobile station and a path length information notifying means. Then, the path length information notifying means obtains the optimum path length based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum path length, and the RAKE receiver of the RAKE receiver according to the optimum path length information. The number of taps of the transversal filter is variably set.

Therefore, even if the radio environment changes, it is possible to set the optimum path length for the RAKE receiver of the mobile station, so that high-quality reception with a high S / N and less transmission errors is always performed. It is possible to provide a wireless communication device for a base station capable of performing the above.

The base station radio communication apparatus of the present invention comprises a measuring means for measuring the state of the radio transmission path with the mobile station and a path length information notifying means. Then, the path length information notifying means obtains the optimum path length based on the measurement result of the measuring means, and notifies the mobile station of information indicating the optimum path length, and RA according to the optimum path length information.
The number of taps of the transversal filter of the KE receiver is variably set.

Therefore, even if the radio environment changes, the optimum number of finger circuits can be operated in the RAKE receiver of the mobile station, and as a result, high quality reception with high S / N and few transmission errors can be obtained. It is possible to provide a spread spectrum wireless communication system capable of performing.

In the mobile station radio communication apparatus of the present invention, a RAKE receiver having a transversal filter for synthesizing a plurality of identical transmission signals received with a time difference and reproducing the transmission signals, and tap control means. It has and. The tap control means variably sets the number of taps of the transversal filter of the RAKE receiver according to the optimum path length information notified from the base station.

Therefore, even if the radio environment changes, it is possible to set the optimum path length for the RAKE receiver of the mobile station, so that high-quality reception with high S / N and few transmission errors is always performed. It is possible to provide a mobile station wireless communication device.

In the radio communication device for mobile station of the present invention, R having a plurality of finger circuits for synthesizing a plurality of identical transmission signals received with a time difference and reproducing the transmission signals.
It has an AKE receiver and finger control means. The finger control means selectively operates the plurality of finger circuits of the RAKE receiver according to the optimum finger number information notified from the base station.

Therefore, even if the radio environment changes, the optimum number of finger circuits can be operated in the RAKE receiver of the mobile station, so that the S / N is always high and the reception quality is high and the transmission error is small. It is possible to provide a mobile station wireless communication device capable of performing the following.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a cellular mobile communication system according to an embodiment of the present invention.

FIG. 2 is a circuit block diagram showing a main part configuration of a base station of a system according to an embodiment of the present invention.

FIG. 3 is a diagram showing a transmission format of optimum path length information in a system according to an embodiment of the present invention.

FIG. 4 is a diagram showing an example of a configuration of a spread code generator.

FIG. 5 is a circuit block diagram showing a main configuration of a mobile station of the system according to the first embodiment of the present invention.

FIG. 6 is a diagram showing an example of the configuration of a matched filter.

7 is a signal waveform diagram showing an example of a pulse train output from the matched filter shown in FIG.

8 is a circuit block diagram showing an example of a configuration of a transversal filter type RAKE receiving unit in the mobile station shown in FIG.

9 is a transversal filter type RA shown in FIG.
The figure for demonstrating the operation example of a KE receiver.

FIG. 10 is a circuit block diagram showing a main configuration of a receiver of a mobile station in a system according to another embodiment of the present invention.

FIG. 11 is a diagram showing an example of tap coefficients given to the spread code generator shown in FIG. 4;

[Explanation of symbols]

BS1 to BS3 ... Base station MS1 to MS4 ... Mobile station E1 to E3 ... Radio zone (cell) FL1 to FL4 ... Forward link slot RL1 to RL4 ... Reverse link slot 11, 31, 71 ... Antenna 12 ... Antenna duplexer ( DUP) 13I, 13Q, 32I, 32Q ... Mixer 14, 33 ... Local oscillator 15, 34 ... π / 2 phase shifter 16I, 16Q, 35I, 35Q, 363 ... Low pass filter (LPF) 17, 36 ... Matched filter 18, 37 ... RAKE receiver 18a ... RAKE receiving section 18b ... Radio transmission path measuring section 19 ... Base station control circuit 19a ... Path length information notification control means 21 ... Transmission data generating section 22 ... Modulation circuit (MOD) 23 ... Spreading Code generator 24 ... Transmitter 38 ... Path length information extraction unit 72 ... High frequency demodulation circuit 74 ... Finger information Extraction unit 75 ... Symbol combiner 361, 371 ... Delay line 362 ... Multiplier 372 ... Tap group 373 ... Adder 374 ... Received data determination unit 375 ... Parameter adaptive setting unit 376 ... Subtractor 731-73n ... Finger circuit

Claims (8)

[Claims] 1. A base station and a mobile station wirelessly communicate a transmission signal by a spread spectrum communication method via a radio transmission path, and the mobile station receives a plurality of identical transmission signals with a time difference. With a transversal filter
In a spread spectrum wireless communication system that reproduces the transmission signal by combining with a KE receiver, the base station includes a measuring unit for measuring a state of a wireless transmission line with the mobile station, and a measuring unit for measuring the state of the wireless transmission line. And a path length information notifying unit for notifying the mobile station of information indicating the optimum path length based on the measurement result, and the mobile station is notified from the base station. A spread spectrum wireless communication system comprising tap control means for variably setting the number of taps of the transversal filter according to optimum path length information. 2. The tap control means variably sets the number of taps of the transversal filter to be operated according to the optimum path length information notified from the base station, and sets the tap coefficient of the tap set in this operating state, The spread spectrum wireless communication system according to claim 1, wherein the state of the wireless transmission path is estimated and adaptively variably controlled based on the estimation result. 3. A base station and a mobile station wirelessly communicate a transmission signal via a wireless transmission line by a spread spectrum communication method, and the mobile station receives a plurality of identical transmission signals with a time difference. In a spread spectrum wireless communication system for reproducing the transmission signal by a RAKE receiver having a plurality of finger circuits, the base station comprises a measuring means for measuring a state of a wireless transmission path with the mobile station, The optimum number of fingers is obtained based on the measurement result of the measuring means, and finger information notifying means for notifying the mobile station of the information indicating the optimum number of fingers, and the mobile station, from the base station Spread spectrum radio characterized by comprising finger control means for selectively operating the plurality of finger circuits according to the notified optimum finger information. Shin system. 4. RAKE having a transversal filter for a plurality of identical transmission signals received with a time difference.
A wireless communication device for a base station, which wirelessly communicates a transmission signal by a spread spectrum communication method with a mobile station having a function of reproducing the transmission signal by combining with a receiver, Measuring means for measuring the state of the wireless transmission path to and from the station, and obtaining the optimum path length based on the measurement result of this measuring means, and notifying the mobile station of information indicating this optimum path length, A base station wireless communication device comprising: a path length information notifying unit for variably setting the number of taps of the transversal filter according to the optimum path length information. 5. A radio transmission path between a mobile station having a function of reproducing a plurality of identical transmission signals received with a time difference by a RAKE receiver having a plurality of finger circuits. In a base station wireless communication device that wirelessly communicates a transmission signal through a spread spectrum communication system via a measuring means for measuring the state of a wireless transmission path with the mobile station, and a measurement result of the measuring means. Based on the optimum number of fingers, information indicating the optimum number of fingers is notified to the mobile station, and finger information notifying means for selectively operating the plurality of finger circuits according to the optimum finger number information is provided. A wireless communication device for a base station, comprising: 6. A mobile station wireless communication device for wirelessly communicating a transmission signal with a base station having a function of transmitting information indicating an optimum path length by a spread spectrum communication method via a wireless transmission path, A RAKE receiver having a transversal filter that synthesizes a plurality of identical transmission signals received with a time difference and reproduces the transmission signals, and the transversal filter according to the optimum path length information notified from the base station. And a tap control means for variably setting the number of taps of the mobile station. 7. The tap control means variably sets the number of taps of the transversal filter to be operated according to the optimum path length information notified from the base station, and sets the tap coefficient of the tap set in this operating state, 7. The mobile station radio communication device according to claim 6, wherein the state of the radio transmission path is estimated and adaptively variably controlled based on the estimation result. 8. A wireless communication device for a mobile station, which wirelessly communicates a transmission signal with a base station having a function of transmitting information indicating the optimum number of fingers by a spread spectrum communication method via a wireless transmission line, A RAKE receiver having a plurality of finger circuits for synthesizing a plurality of identical transmission signals received with a time difference to reproduce the transmission signals; and a plurality of the plurality of finger circuits according to the optimum finger number information notified from the base station. A mobile station wireless communication device comprising: finger control means for selectively operating a finger circuit.