JP2000324014A - Spread spectrum radio communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spread spectrum radio communication device that its circuit scale is reduced to reduce the cost and that can cope with even revision of the communication standards. SOLUTION: A CDMA reception section 4 reproduces received data from a signal sent by a spread spectrum communication system. A correlation section 41 is provided with 37 correlators. A DSP section 40 applies digital signal processing to correlation outputs from the correlators according to a random logic in response to an instruction of a control section 5. The control section 5 is configured mainly of a microprocessor such as an MPU and realizes the operation of the spread spectrum radio communication device through the total control of each section of the spread spectrum radio communication device, and gives an instruction to the DSP section 40 in response to a type of communication (high-speed data communication or voice communication) and applies control processing according to the random logic to a searcher and a finger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Related to wireless communication systems such as mobile phone systems and wireless LANs, especially CDM using spread spectrum signals
The present invention relates to a spread spectrum wireless communication device used in an A (Code Division Multiple Access) wireless communication system.

[0002]

2. Description of the Related Art In recent years, as one of communication systems suitable for a wireless communication system, a spread spectrum communication system, which is resistant to interference and interference, a so-called CDMA system, has been receiving attention. In a wireless communication system using the spread spectrum communication method, digitized audio data or image data is assumed as transmission data.

In the spread spectrum method, these data are converted into data of a digital modulation method such as QPSK, multiplied by a spread code of a pseudo noise code (PN code), and converted into a broadband baseband signal. The signal is converted into a radio frequency signal and transmitted.

[0004] On the other hand, the receiving-side device despreads the received radio signal using the same code as the spreading code used on the transmitting side, and then performs digital demodulation such as QPSK to receive data. Is configured to be played.

[0005] Transmission data has been mainly digital audio data of about 8 kbps or about 13 kbps, but data transmission of 64 kbps is now being performed.

For data transmission at 64 kbps, for example, transmission and reception of image data, Internet Web, and fax communication are considered. US Standard IS-95 C
In the DMA system, in order to realize data transmission of 64 kbps, eight traffic channels of 8 kbps which have been allocated for voice are used simultaneously.

This means that the data is transmitted at 8 kbps at the time of data transmission.
This is a method in which the data is divided into 8 and transmitted, and the data which is divided by 8 on the receiving side is received by each traffic channel, and the data is demodulated and combined.

As described above, IS-95 CDMA
In order to realize data transmission of 64 kbps, the mobile phone receives radio signals of eight traffic channels from the base station.

For this reason, if the same receiving method as that for receiving voice data is adopted without devising, the scale of an LSI or the like for performing baseband signal processing, or simply the hardware scale, becomes large, and the data transmission for voice and data transmission is performed. There is a problem in that an inexpensive LSI that can be shared with the user cannot be realized.

[0010] In addition, by creating an LSI with random logic by expanding the voice communication for data transmission, the 64k
bps data transmission, IS-
There is a problem that it is not possible to immediately respond to changes in standards such as 95.

[0011]

In a conventional spread spectrum radio communication apparatus, in order to perform voice communication and high-speed data communication, the scale of a circuit for processing a baseband signal becomes large and cost is reduced. There has been a problem that the number of communication lines has increased or the communication standard cannot be changed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and provides a spread spectrum wireless communication apparatus capable of reducing the circuit scale, reducing the cost, and responding to a change in communication standard. The purpose is to:

[0013]

In order to achieve the above object, the present invention relates to a spread spectrum radio communication apparatus for performing radio communication of a spread spectrum system, wherein a plurality of correlations between a received signal and a spread code are obtained. And DSP processing means for realizing the function as a plurality of fingers and the function as a plurality of searchers using the correlations obtained by the plurality of correlation means, and voice communication or data communication, A DSP control means for changing the number of at least one of the finger and the searcher that functions is provided.

In the spread spectrum wireless communication apparatus having the above configuration, the number of at least one of the finger and the searcher that functions is changed depending on whether the communication is voice communication or data communication.

Therefore, according to the spread spectrum radio communication apparatus having the above configuration, the number of fingers and searchers corresponding to the type of communication are realized by the DSP processing, and the spread spectrum signal is received. The cost can be reduced by reducing the circuit scale as compared with the case of taking a redundant configuration according to the above, and by implementing this in the DSP processing, it is possible to cope with a change in the communication standard.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a spread spectrum wireless communication apparatus according to an embodiment of the present invention. Here, a receiving system according to the present invention will be particularly described.

The spread spectrum wireless communication apparatus includes an antenna 1, an analog receiver 2, an A / D converter 3, a CDM
An A receiving unit 4 and a control unit 5 are provided. A radio frequency signal transmitted from a base station of a mobile communication system is received from space by an antenna 1, and the received signal is down-converted to a baseband signal by an analog receiver 2.

The A / D converter 3 includes an analog receiver 2
The baseband signal down-converted is converted into I-channel and Q-channel digital signals (9.8 MHz).
z), and outputs each to the CDMA receiver 4.

The CDMA receiving section 4 receives a signal transmitted by the spread spectrum communication system, and comprises a correlating section 41 and a DSP section 40. The correlation unit 41
The number of correlators 4101 to 4137 is provided. This correlator 4
Reference numerals 101 to 4137 denote complex correlators each including the correlator 60 shown in FIG.

The correlator 60 includes multipliers 61a, 61b, 6
1c, 61d, 61e, 61f and adders 62a, 62
b, integrators 63a and 63b, and latch circuits 64a and 64
4b, which is commonly used in IS-95 systems, and is described in detail in “CDMA Principles of Spread Spectrum Communicati.
ons ”Author A. Viterbi Publisher Addison Wesley Publishin
g pp. 43 ".

The correlator 60 includes an I-channel and a Q-channel digital signals from the A / D converter 3 and a PN code and a Walsh code generated by a PN code generator (PN) 421 of a code generator 42 described later. Generator (Wa
lsh) 422, each of which takes a correlation with the Walsh code and outputs a correlation output corresponding to the magnitude of the correlation.

The correlation outputs for the I and Q quadrature signals are input to latch circuits 64a and 64b, respectively.
Latch the timing of both, as the register output,
Output to the DSP unit 40.

The PN code generator 421 and Wal
The sh code generator 422 includes a PN code (I sequence and Q sequence) having a phase corresponding to an instruction from the control unit 5 described later and Wal
Each sh code is arbitrarily generated.

The DSP unit 40 includes a code generation unit 42 for generating a PN code and a Walsh code in accordance with an instruction from the control unit 5, and performs digital signal processing on the correlation output output from the correlators 4101 to 4137. The main processing functions include a complex multiplication unit 43, a channel estimation unit 44, a DLL follow-up unit 45, and a monitor unit 4.
6 and a Deskew unit / symbol combining unit 47.

As shown in FIG. 2, the code generator 42 includes a PN code generator (PN) 421 for generating a PN code.
And a Walsh code generator (Walsh) 422 for generating a Walsh code.

The complex multiplier 43 includes 21 complex multipliers 4
Each of the multipliers 301 to 4321 performs complex multiplication. The channel estimator 44 includes four channel estimators 4
Each of the estimators obtains phase information and amplitude information of a signal to be received based on the correlation output.

The DLL follow-up unit 45 includes four DLL follow-up circuits 4501 to 4504. Each of the DLL follow-up circuits performs synchronous follow-up of the PN code generated by the PN code generator 421. And a DLL follow-up circuit 70 shown in FIG.

The DLL follow-up circuit 70 includes a squaring circuit ((.))
² ) Consisting of 71a, 71b, a subtractor (Σ) 72, a loop filter 73, and a voltage controlled oscillator (VCO) 74.

One of the two correlators 41x and 41y of the correlators 4101 to 4137 has a PN code generator 42
The PN code E (Early) generated in step 1 is used to obtain a correlation output with the received signal.
Using the PN code L (Late) generated at 21, a correlation output with the received signal is obtained. Note that the PN codes E and L
Are separated from each other by one chip as shown in FIG.

The correlation output between the PN code E and the received signal is
The signal is input to the squaring circuit 71 a, squared here, and input to the subtractor 72. This is shown in FIG. On the other hand, P
The correlation output between the N code L and the received signal is calculated by a squaring circuit 71b.
, Squared here, and input to the subtractor 72. This is shown in FIG. FIG. 5A shows a correlation output obtained at a desired target PN code phase.

The subtractor 72 subtracts the input from the squaring circuit 71a from the input from the squaring circuit 71b. This is shown in FIG. Then, the result of the subtraction is input to the loop filter 73.

The loop filter 73 smoothes the result of the subtraction, and the voltage controlled oscillator 74 generates a pulse having a frequency corresponding to the voltage value of the smoothed result. Then, the PN code generator 421 generates the PN codes L and E at a period corresponding to the pulse generated by the voltage controlled oscillator 74.

With the above loop control, the subtractor 7
Control is performed so that the phase remains at the point B of the output of the
Synchronous tracking of the PN code generated by the N code generator 421 is performed.

The monitor section 46 includes two monitor circuits 46.
1, 462, each of which monitors the above-mentioned correlation output and detects the position of the phase of the PN code, and is used in a searcher described later.

FIG. 6 shows the correlators 4101 to 4137 described above.
Among them, the correlation outputs of a set of four correlators functioning as a searcher are shown. In this case, the phase of the PN code given to each correlator is shifted by 1/2 chip.

Of the four correlation outputs, the phase of the PN code corresponding to the one having the maximum power is detected,
A phase range used by a correlator functioning as a finger described later is detected.

For this reason, one searcher requires two at a time.
The phase range of the chip can be verified, and after searching the phase in the range shown in FIG. 6A, the phase in the range shown in FIG. 6B is searched.

The Deskew / symbol combining unit 47
The output of the finger is subjected to demodulation processing to generate received data. When a plurality of finger outputs are input, the timing of a plurality of data reproduced from these is aligned in the Deskew section. After that, the addition is performed in the symbol combining section.

The control unit 5 is mainly constituted by a microprocessor such as an MPU, and realizes the operation as a spread spectrum wireless communication device by controlling each unit of the spread spectrum wireless communication device in a comprehensive manner. The control unit 5 controls the type of communication (high-speed data communication or voice communication) in addition to well-known general control means in this type of spread spectrum wireless communication device.
Control means is provided for instructing the DSP unit 40 and performing control processing for forming searchers and fingers by random logic.

Next, the operation of the spread spectrum radio communication apparatus having the above configuration will be described below. First, a case where voice communication is performed will be described.

In this case, the control unit 5 gives an instruction to the DSP unit 40 and, as shown in FIG.
Four fingers 101a to 104a and two searchers 201a and 202a are formed by random logic.

FIG. 8 shows the configuration of the finger and the searcher in detail. Each finger 101a-10
4a is configured using four correlators, one complex multiplier, one channel estimator, and one DLL tracking circuit.
Each of the searchers 201a and 202a is configured using four correlators and one monitoring circuit.

In FIG. 8, the fingers 101a to 101a
4a and the searchers 201a and 202a have the same configuration, respectively, and particularly show the finger 101a and the searcher 201a in detail. For this reason,
The description of the fingers 102a to 104a and the searcher 202a is omitted.

The finger 101a has two correlators 410
1, 4102 and the DLL follow-up circuit 4501,
An N-code following circuit 80 is formed, and a correlator 4101,
The correlation output obtained in 4102 is a DLL tracking circuit 4501
, And the DLL tracking circuit 4501 performs synchronous tracking of the PN code generated by the code generator 42.

The correlator 4103 sets a Walsh code for pilot, and inputs a correlation output to the channel estimator 4401. On the other hand, the channel estimator 4
401 obtains phase information and amplitude information of a signal to be received based on the correlation output of the correlator 4103 and inputs the information to the complex multiplier 4301. Then, the remaining correlator 4104
, A Walsh code for data is set, and the correlation output obtained here is input to the complex multiplier 4301.

On the other hand, complex multiplier 4301 applies the above-mentioned channel estimator 440 to the input correlation output.
1 is complex-multiplied, the received data of 16 bits is demodulated by this multiplication, and this demodulated data is
Input to the skew part / symbol combining part 47.

On the other hand, the Deskew section / symbol combining section 47 outputs the one obtained by the fingers 101a to 104a.
Symbols are synthesized by aligning the timings of the 6-bit demodulated data.

In the searcher 201a, four correlators 41
The correlation outputs of 17, 4118, 4119, and 4120 are input to the monitor circuit 461. On the other hand, the monitor circuit 461 detects the position of the phase of the PN code, and notifies the control unit 5 of the detected phase.

Next, a case where data communication is performed will be described. In this case, the control unit 5 gives an instruction to the DSP unit 40 and, as shown in FIG. 9, causes the CDMA receiving unit 4 to include three fingers 101b to 103b and one searcher 201.
a is formed by random logic.

FIG. 10 shows the structure of the finger in detail. Each finger 101b to 103b has 11
Each of the number of correlators, eight complex multipliers, one channel estimator and one DLL tracking circuit.

In FIG. 10, the fingers 101b to 101b
03b has the same configuration, and particularly shows only the finger 101b in detail. Therefore, the description of the fingers 102b and 103b is omitted. Also, for the searcher 201a, FIG.
The description is omitted because it is the same as the searcher 201a shown in FIG.

The finger 101b has two correlators 410
1, 4102 and the DLL follow-up circuit 4501,
An N-code following circuit 80 is formed, and a correlator 4101,
The correlation output obtained in 4102 is a DLL tracking circuit 4501
, And the DLL tracking circuit 4501 performs synchronous tracking of the PN code generated by the code generator 42.

The correlation output obtained by correlator 4103 is input to channel estimator 4401. On the other hand, the channel estimator 4401 provides the pilot Wa
Based on the correlation output obtained by setting the lsh code in the correlator 4103, phase information and amplitude information of the signal to be received are obtained and input to the complex multipliers 4301 to 4308.

The remaining eight correlators 4104 to 4111 are:
A Walsh code for data is set for each, and the correlation output obtained here is output to the corresponding complex multiplier 4.
301 to 4308.

On the other hand, complex multipliers 4301 to 43
Reference numeral 08 denotes a complex multiplication of the input correlation output by the information obtained by the channel estimator 4401 to demodulate the 16-bit received data by the multiplication, and divides the demodulated data into a Deskew part / symbol combination. Input to the section 47.

On the other hand, the Deskew / symbol combining unit 47 obtains the one obtained by the fingers 101b to 103b.
Symbols are synthesized by aligning the timings of the 6-bit demodulated data.

In the symbol synthesis, the demodulated data obtained from the correlation output for demodulating the Fundamental channel and the demodulated data obtained from the correlation output for the demodulation of the Supplemental channel are output from the respective fingers. Symbols are synthesized.

For example, in the US standard IS-95,
When data communication of 64 kbps is performed using eight traffic channels, eight correlators are used for each finger.
Demodulated data is obtained for tal demodulation, and the demodulated data output from each finger is symbol-synthesized by the Deskew / symbol synthesizing unit 47 at the same timing.

Then, from the correlation outputs obtained from the remaining seven correlators, demodulated data for demodulation of the supplemental channel is obtained, and these demodulated data output from the respective fingers are sent to the Deskew / symbol combining unit 47. Synthesize symbols at the same timing.

As described above, in the spread spectrum wireless communication apparatus having the above configuration, when performing 64 kbps data communication, it is assumed that high-speed movement such as voice communication is not performed. As shown in FIG. 11, the number of searchers and fingers to be used is reduced by one by one, and the number of correlators for data demodulation used by each finger is reduced by random logic, as shown in FIG. The number is increased from one for voice to eight to support 64 kbps data communication.

Therefore, according to the spread spectrum radio communication apparatus having the above configuration, as shown in FIG. 12, the required number of correlators is smaller than that of the conventional configuration in which voice communication and data communication are redundantly configured. Since the number is changed from 104 to 74, the number can be reduced by 30% or more, so that the circuit scale can be reduced and the cost can be reduced.

Further, since the Walsh codes given to a plurality of correlators used for despreading are arbitrarily combined and the output of the correlator is processed by a register and the random logic realized by the DSP unit 40, the correlator The degree of freedom can be increased, and changes in the communication standard can be handled by changing the firmware of the DSP.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the PN code tracking circuit 80 is configured by using two correlators and one DLL tracking circuit, but instead of this, for example, as shown in FIG. tau-dith
The er tracking circuit 4511 may be configured to be used one by one.

FIG. 14 shows the tau-dit shown in FIG.
The her tracking circuit 4511 is shown in detail, and a correlator 4101 multiplies a received signal by a PN code generated by a PN code generator 421 described later to obtain a correlation with the received signal.

The correlation output is calculated by the square circuit ((·) ² ) 9
The result is squared by 1 and input to the multiplier 92. Then, a gate signal g (f) as shown in FIG. 15 is generated by the gate signal generator 93 and input to the multiplier 92, where the output of the squaring circuit 91 and the gate signal g (f) are output. Multiply.

The multiplication result ε (f) is smoothed by the loop filter 94, and a pulse having a frequency corresponding to the voltage value of the smoothing result is generated by the voltage controlled oscillator (VCO) 95. Then, the PN code generator 421 outputs the PN codes L and E at a period corresponding to the pulse generated by the voltage controlled oscillator 95.
Generate

The selection circuit 96 alternately uses the PN codes L and E from the PN code generator 421 in accordance with the gate signal g (t) generated by the gate signal generator 93 to generate a correlator 410.
Output to 1.

As described above, when the PN code follow-up circuit 80 is configured, the input ε (f) of the loop filter 94 is
Is controlled so as to follow the point B. According to such a configuration, the PN code can be tracked.
Since the number of correlators can be reduced by one as compared with the PN code follower circuit 80 shown in (1), four correlators can be further reduced as a whole. In addition, it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0069]

As described above, according to the present invention, a number of fingers and searchers corresponding to the type of communication are realized by DSP processing to receive a spread spectrum signal.

Therefore, according to the present invention, it is possible to provide a spread spectrum wireless communication apparatus capable of reducing the circuit scale, reducing the cost, and responding to a change in the communication standard.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of an embodiment of a receiving system of a spread spectrum wireless communication apparatus according to the present invention.

FIG. 2 is a circuit block diagram showing a configuration of a correlator of the correlation unit shown in FIG.

FIG. 3 is a circuit block diagram illustrating a configuration of a DLL tracking circuit of the DLL tracking unit illustrated in FIG. 1;

FIG. 4 is a view for explaining the phase of a PN code generated by a PN code generator of the DLL tracking circuit shown in FIG. 3;

FIG. 5 is a view for explaining PN code synchronization tracking control of the DLL tracking circuit shown in FIG. 3;

FIG. 6 is a diagram showing the power of each correlation output of a set of four correlators functioning as a searcher.

FIG. 7 is a functional block diagram showing the configuration of the receiving system of the spread spectrum wireless communication apparatus shown in FIG. 1 during voice communication.

FIG. 8 is a functional block diagram for describing in detail a finger and a searcher shown in FIG. 7;

9 is a functional block diagram showing a configuration of the receiving system of the spread spectrum wireless communication apparatus shown in FIG. 1 during data communication.

FIG. 10 is a functional block diagram for explaining in detail a finger shown in FIG. 7;

FIG. 11 is a diagram for explaining a difference in configuration between a spread spectrum wireless communication apparatus according to the present invention and a conventional apparatus.

FIG. 12 is a diagram for explaining a configuration difference between a spread spectrum wireless communication apparatus according to the present invention and a conventional apparatus.

FIG. 13 is a functional block diagram showing a configuration of a tau-dither tracking circuit provided in place of the DLL tracking circuit shown in FIG. 3;

FIG. 14 is a functional block diagram for explaining in detail the tau-dither tracking circuit shown in FIG. 13;

FIG. 15 is a diagram for explaining a gate signal generated by a gate signal generator of the tau-dither tracking circuit shown in FIG. 13;

FIG. 16 is a diagram for explaining PN code synchronization tracking control of the tau-dither tracking circuit shown in FIG. 14;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Antenna 2 ... Analog receiver 3 ... A / D converter 4 ... CDMA receiving part 40 ... DSP part 41 ... Correlation part 4101-4137, 41x, 41y, 60 ... Correlator 42 ... Code generation part 421 ... PN code generator (PN) 422 ... Walsh code generator (Walsh) 43 ... Complex multiplier 4301-4321 ... Complex multiplier 44 ... Channel estimator 4401-4404 ... Channel estimator 45 ... DLL follower 4501-4504, 70 ... DLL follower 4511 tau-dither tracking circuit 46 monitor units 461, 462 monitor circuit 47 Deskew unit / symbol synthesis unit 5 control units 61a, 61b, 61c, 61d, 61e, 61f, 9
2 Multipliers 62a, 62b Adders 63a, 63b Integrators 64a, 64b Latch circuits 71a, 71b, 91 ... Squaring circuits ((.) ² ) 72 ... Subtractors (Σ) 73, 94 ... Loop filters 74 , 95 ... voltage controlled oscillator (VCO) 80 ... PN code tracking circuit 93 ... gate signal generator 96 ... selection circuit 101a-104a, 101b-103b ... finger 201a, 202a ... searcher

Claims (5)

[Claims] 1. A spread spectrum wireless communication apparatus for performing spread spectrum wireless communication, comprising: a plurality of correlation means for obtaining a correlation between a received signal and a spread code; and a correlation obtained by the plurality of correlation means. DSP processing means for realizing the function as a plurality of fingers and the function as a plurality of searchers, and a DSP for changing the number of at least one of the fingers and the searcher according to voice communication or data communication A spread-spectrum wireless communication apparatus, comprising: a control unit. 2. The DSP control means controls the DSP processing means so as to reduce the number of at least one of the finger and the searcher when performing data communication compared to when performing voice communication. The spread spectrum wireless communication apparatus according to claim 1, wherein the apparatus performs control. 3. The DSP control means, when performing data communication, reduces the number of fingers and increases the number of correlation means used per finger as compared with the case of performing voice communication. 3. The spread spectrum wireless communication apparatus according to claim 1, wherein said DSP processing means is controlled. 4. The DSP control means performs phase tracking of a spread code used by the correlation means when the DSP processing means performs voice communication, based on the correlation obtained by the two correlation means. In a case where data communication is performed, control is performed so as to perform processing corresponding to a DLL tracking circuit. On the other hand, Ta performed based on the correlation obtained by one correlation means is used.
The spread spectrum wireless communication apparatus according to any one of claims 1 to 3, wherein control is performed so as to perform the processing corresponding to a u-Dither tracking circuit. 5. The method according to claim 1, wherein the spreading codes given to the plurality of correlating means are arbitrarily combined, and the correlation obtained by each correlating means is output to the DSP processing means via a memory means. 5. The spread spectrum wireless communication apparatus according to any one of 4.