JP2000252858A - Multi-channel correlation receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the correlation characteristics of the same incoming waves with a simple configuration. SOLUTION: The multi-channel correlation receiver is provided with a plurality of antennas 2a-2d that receive the radio wave of a CDMA signal, a P/S conversion circuit 21 that converts the radio wave signal received by a plurality of antennas 2a-2d into a serial signal using each antenna for each channel, a demodulator 35 that demodulates the serial signal into a couple of baseband signals, an A/D converter 22 that converts each demodulated base band signal into a digital baseband signal, a digital correlation device 23 that sequentially calculates the correlation characteristics between the data of each channel in time division in each baseband signal sequentially outputted from the A/D converter 22 and a PN signal used for spread spectrum processing, and an S/P conversion circuit 33 that converts individual correlation characteristics outputted sequentially from the digital correlation device 23 into parallel data, consisting of a plurality of correlation characteristics for each channel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-channel multiplexed wave phase difference measuring device for examining from which direction and how many radio waves arrive at a mobile terminal. The present invention relates to a multi-channel correlation receiving apparatus that is incorporated in a measuring apparatus, receives incoming waves from each direction while moving, continuously and simultaneously with a plurality of antennas, and obtains a correlation to check the direction of arrival.

[0002]

2. Description of the Related Art In recent years, mobile communication systems such as mobile phones and PHSs have been rapidly spreading. In particular, in the future, PH
S, etc., and a CDMA (code division multiple a
ccess) It is considered that a mobile communication system using a communication system is widely used.

[0003] Therefore, in a mobile communication system employing the CDMA system as the communication system, the designer of the system must consider the installation environment of the relay station (relay antenna) in consideration of any environment in which the mobile terminal is used. Must be selected and set. However, even if each relay station (relay antenna) is set to be the best in theory, there are many radio wave reflectors such as buildings in cities. Therefore, the same radio wave transmitted from the same radio wave transmission source may be received by a single mobile terminal via a plurality of routes with slightly different reception times.

[0004] Therefore, it is also very important in constructing a mobile communication system to find out from which direction the same radio wave transmitted from the same radio wave transmission source arrives at an arbitrary position. Test items.

As shown in FIG. 6, a part of the multi-channel multiplex wave phase difference measuring device for testing such items is mounted on the test vehicle 1. In addition to the direct wave 4 from the same radio wave source 3, a plurality of reflected waves 6 reflected by each building 5 are incident on the antenna 2 of the test vehicle 1. The multi-channel multiplex wave phase difference measuring device is composed of a multi-channel correlation receiving device 7 mounted on the test vehicle 1 shown in FIG. 7 and an analyzing device 8 installed in the experimental analysis room shown in FIG. I have.

As shown in FIG. 7, the multi-channel correlation receiving device 7 includes, for example, 4
Antennas 2a, 2b, 2c, 2d and four CDMAs connected to the antennas 2a, 2b, 2c, 2d
Receiving sections 9a, 9b, 9c, 9d and each CDMA receiving section 9
a, 9b, 9c, 9d for each antenna output from
That is, each correlation characteristic R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 , R _Q3 , each correlation characteristic for each baseband signal I, Q for each channel,
The data recorder 10 writes R _I4 and R _Q4 on a recording medium such as a magnetic tape.

On the other hand, an analyzer 8 installed in the experimental analysis room
As shown in FIG. 8, a data recorder for reproducing each correlation characteristic R _I1 to R _Q4 for each baseband signal for each channel recorded on the recording medium in data recorder 10 mounted on the test vehicle 1 12 and each reproduced correlation characteristic R _I1
The to R _Q4 an A / D converter 13 for converting A / D, is constituted by a computer 14 for calculating the direction of the incoming wave from the correlation characteristic R _I1 to R _Q4 which is converted A / D.

The CDMA receiving sections 9a to 9d of the multi-channel correlation receiving apparatus 7 have the same configuration, for example, as shown in FIG. The high frequency CDAM signal received by the antenna 2a is converted into an intermediate frequency by the input RF interface 15, and then demodulated by the demodulation unit 16 into a pair of baseband signals I and Q. The baseband signals I and Q demodulated by the demodulation unit 16 are input to the analog correlator 17. The analog correlator 17 receives the input baseband signals I and Q and the PN signal output from the reference PN (pseudo noise) pattern generator 18 (the PN signal used for spreading the baseband signal in the radio wave source 3). correlation characteristic R _I and have) the same characteristics, to calculate the R _Q.

As a specific method for calculating the correlation characteristics R _I and R _Q in the analog correlator 17, the bit positions of the input baseband signals I and Q are fixed, and the fixed baseband signals I and Q are fixed. The bit data of I and Q is multiplied by each bit data of one period of the PN signal (an EXNOR value is calculated in an actual logic circuit), and the multiplied value is calculated over one period of the PN signal. The sum is used as the correlation value of the bit data of each of the baseband signals I and Q. When the correlation value for one bit data of the baseband signals I and Q is obtained, the bit data position of the baseband signals I and Q is shifted, and the correlation value for the corresponding bit data is obtained by the same method.

When the correlation values of at least the bit data of 6 to 8 periods of the PN signal in each of the baseband signals I and Q are obtained and arranged in time series, the correlation characteristics of each baseband signal shown in FIG. R _I and R _Q are obtained.
The bit positions of the peaks in the correlation characteristics R _I and R _Q are the synchronization positions of the baseband signals I and Q with respect to the PN signal.

In this manner, the correlation characteristics R _I1 , R _Q1 ,
The data recorder 10 stores and holds R _I2 , R _Q2 , R _I3 , R _Q3 , R _I4 , and R _{Q4 on} a recording medium such as a magnetic tape.

Each of the antennas 2a to 2d receives, in addition to the direct wave 4 from the radio wave source 3, a plurality of reflected waves 6 reflected by each building 5 with a slight delay from the direct wave 4. Are sequentially incident with a delay.

Therefore, the multi-channel correlation receiving apparatus 7 individually collects each correlation characteristic for the direct wave 4 and each reflected wave 6.

Each correlation characteristic R of the direct wave 4 and each reflected wave 6
_I1~ After R _Q4 is stored and held in a recording medium such as a magnetic tape by the data recorder 10, the analysis device 8 installed in the experimental analysis chamber, after being converted A / D, the computer 1
4 is input.

In the computer 14, as shown in FIG. 11, each correlation characteristic R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 , R _Q3 , R _I4 , R R1 for each baseband signal for each channel.
Each peak value in _{Q4 P I1, P Q1, P} I2, P Q2, P I3,
_Find P _Q3 , P _I4 , and P _Q4 . Then, as shown in FIG. 12, the phase θ is obtained from the peak values P _I and P _{Q of the} baseband signals I and Q.

Θ = tan^-1(P_Q/ P_I) Phase θ of each channel of 1-4₁, Θ_Two, Θ_Three, Θ_FourSeeking
Each phase θ₁, Θ _Two, Θ_Three, Θ_FourAre arranged in ascending order
Incoming wave (direct wave 4
And the direction of arrival of the reflected wave 6) can be estimated.

The arrangement order in the case of being arranged in the order of magnitude shown in FIG. 12 indicates that the radio waves arrive from the right direction in FIG. Conversely, as shown in FIG. 13 (b), when the magnitude relationships of the phases θ ₁ , θ ₂ , θ ₃ , θ ₄ of the respective channels are in the reverse order, the radio wave arriving from the left direction in FIG. Indicates that there is.

Further, in FIG. 7, in the case of a radio wave arriving from the front, as shown in FIG. 13A, the phases θ ₁ , θ ₂ , θ ₃ and θ _{4 of} all the channels are equal to 45 °. I do.

Therefore, the signals are transmitted from the same transmission source 3,
It is possible to measure the direction of arrival of each incoming wave (multiplexed wave) received at a short interval, that is, the direct wave 4 and the reflected wave 6.

[0020]

However, the following problems still need to be improved in the multi-channel correlation receiving apparatus incorporated in the above-described multi-channel multiplexed phase difference measuring apparatus.

That is, a PN (pseudo noise) signal used for spread spectrum in an actual CDMA signal is composed of, for example, a 10-stage shift register and an exclusive OR gate, and its bit period is (2 ¹⁰ −1) = 11023. And the signal speed (bit rate) of the CDMA signal is about 30 Mbps (MHz). As a result, the period of the PN (pseudo noise) signal is 1023/30 = 34.1 μS
It is about.

Therefore, the time required for the analog correlator 17 to calculate the correlation value for one bit data of the baseband signals I and Q is 34.1 μS, which is, for example, six times the period of the PN signal. About 600
When calculating the correlation characteristics R _I and R _Q using zero data, the time required to calculate one correlation characteristic R _I and R _Q is 34.1 μS × 6000 = 204.6 ms,
About 0.2 seconds are required.

In the input RF interface 15 incorporated in each of the CDMA receiving sections 9a to 9d, FIG.
As shown in FIG. 4, an amplifier 15a for amplifying a received high-frequency CDMA signal and a local oscillator (LO) 15
b, a mixer 15c, an LPF 15d, an intermediate frequency oscillator (IF) 15e, and the like. In addition, each CDM
In the demodulation unit 16 incorporated in the A receiving units 9a to 9d, as shown in FIG.
a, mixers 16b, 16c, signal divider 16d, LPF
16e, 16f, etc. are incorporated.

As described above, in order to calculate the phases θ ₁ , θ ₂ , θ ₃ , and θ ₄ of the channels 1 to 4 and accurately compare the magnitude relations, the input RF interface 15 and the input RF interface 15 It is necessary that the characteristics of the demodulation unit 16 of each channel match exactly. However, as shown in FIG. 14, many electronic members are incorporated in the input RF interface 15 and the demodulation unit 16. Therefore, it is very difficult to completely match all the characteristics including the phase characteristics of each electronic member. As a result, it is very difficult to accurately measure the direction of arrival of each incoming wave.

To solve such inconveniences,
Each DMA signal received by the antennas 2a to 2d is
The time is shifted by the DMA receiver, and each base is set for each channel.
Each correlation characteristic R for each of the band signals I and Q_I1, R_Q1, R_I2,
R_Q2, R_I3, R_Q3, R_I4, R _Q4It is possible to measure
It is.

However, as described above, it takes about 0.2 seconds to calculate the correlation characteristics R _I and R _Q for one channel. Therefore, it takes about one second to calculate the correlation characteristics R _{I1 to} R _Q4 for four channels. If the measurement time is long as described above, the incoming wave measured on the measurement start channel and the arrival wave on the measurement end channel cannot be regarded as the same incoming wave. As a result, there has been a problem that the arrival direction of the same arriving wave cannot be measured accurately.

The present invention has been made in view of such circumstances, and by using a digital correlator, one demodulator and one correlator can be shared for each channel. Provided is a multi-channel correlation receiving apparatus capable of accurately measuring the correlation characteristics of the same arriving wave with a simple circuit configuration, and thereby accurately measuring the direction of arrival of each arriving wave in a multiplex wave arriving at sequentially shifted times. Aim.

[0028]

In order to solve the above-mentioned problems, a multi-channel correlation receiving apparatus according to the present invention comprises a plurality of CDMA signals which are spread apart by a PN signal and receive orthogonally modulated CDMA signals. Antenna and
A P / S conversion circuit for converting radio wave signals received by a plurality of antennas into a time-divided serial signal using each antenna as a channel, and a pair of serial signals output from the P / S conversion circuit. Demodulator that demodulates the baseband signal into a baseband signal, an A / D converter that converts each baseband signal demodulated by the demodulator into a digital baseband signal, and bases that are sequentially output from the A / D converter. A digital correlator for sequentially calculating the correlation characteristics between the time-divided data for each channel in the band signal and the PN signal used for the spread spectrum, and the correlation characteristics sequentially output from the digital correlator for each channel. And an S / P conversion circuit for converting the data into parallel data having a plurality of correlation characteristics.

In the multi-channel correlation receiving apparatus thus configured, each CDMA signal received by each antenna is converted into a serial signal. Then, the serial signal is demodulated into a pair of baseband signals by a demodulator, and the demodulated pair of baseband signals is A / D converted and then input to a digital correlator.

This digital correlator sequentially calculates the correlation characteristic between the time-divided data of one channel in each baseband signal sequentially output from the A / D converter and the PN signal used for spread spectrum. To go.

In this case, for example, the bit positions of the input baseband signals I and Q are fixed, and the bit data of the fixed baseband signals I and Q are
An EXNOR value with each bit data of one cycle of the PN signal is calculated, and this calculated value is added over one cycle of the PN signal, and this added value is added to the bit data of the baseband signals I and Q. Let it be a correlation value. When the correlation value for one bit data of the baseband signals I and Q is obtained, the bit data position of the baseband signals I and Q is shifted, and the correlation value for the corresponding bit data is obtained by the same method. When time series arranging seeking the correlation values for one cycle of the bit data of the PN signal in the baseband signals I, Q, correlation characteristic R _I for each baseband signal shown in FIG. 10, R _Q is obtained Can be

It is also possible to fix the bit position of each bit data for one cycle in the PN signal and move the bit position of the bit data of each of the input baseband signals I and Q.

The correlation characteristics R _I and R _Q sequentially output from the digital correlator are separated into correlation characteristics for each channel by an S / P conversion circuit.

[0034] Thus, in the digital correlator, the correlation characteristic R _I for one baseband signal, the time required for calculating the R _Q, is divided by the square power of the bit period of the PN signal. Therefore, the time required for calculating the correlation characteristic can be significantly reduced as compared with the conventional analog correlator.
Therefore, even if one digital correlator calculates the correlation characteristics for each baseband signal of each channel in time series, it is necessary to calculate the correlation characteristics for all channels. The time does not increase compared to the conventional device.

Therefore, the number of demodulators and correlators can be limited to one as a whole multi-channel correlation receiving apparatus, so that it is possible to prevent a variation in measured values between channels in the obtained correlation characteristics. Also,
In a multi-channel correlation receiving apparatus according to another invention, a CDMA signal that is spread spectrum and quadrature modulated with a PN signal is provided.
A plurality of antennas spaced apart from each other for receiving signal radio waves, and a P / S for converting radio wave signals received by the plurality of antennas into one time-divided serial signal using each antenna as a channel. A conversion circuit, a demodulator for demodulating the serial signal output from the P / S conversion circuit into a pair of baseband signals, and an A for converting each baseband signal demodulated by the demodulator into a digital baseband signal.
A / D converter, a plurality of storage elements for dividing data of each time-divided one channel in each baseband signal output from the A / D converter into a plurality of partial data and storing the divided data, and a plurality of storage elements A correlation unit for sequentially calculating a partial correlation characteristic between each partial data stored in the storage unit and a PN signal used for spread spectrum, and a partial correlation characteristic corresponding to each partial data sequentially calculated by the correlation unit are added. A correlation adder for calculating a correlation characteristic of each baseband signal for each channel,
An S / P conversion circuit for converting each correlation characteristic sequentially output from the correlation adder into parallel data composed of a plurality of correlation characteristics for each channel.

In the multi-channel correlation receiving apparatus configured as described above, the digital correlator employed in the multi-channel correlation receiving apparatus of the invention described above includes a plurality of storage elements and one
It is composed of one correlation unit and one correlation adder.

In the digital correlator configured as described above, the correlator only needs to sequentially calculate the partial correlation characteristic for each partial data in the plurality of storage elements.
Therefore, the number of operation elements of the correlator can be greatly reduced to approximately one-half the number of storage elements compared to the digital correlator in the above-described invention, so that the circuit configuration of the entire apparatus can be further simplified.

[0038]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a multi-channel correlation receiving apparatus according to the present invention. The same parts as those of the conventional multi-channel correlation receiving apparatus shown in FIGS. 7, 9 and 14 are denoted by the same reference numerals, and detailed description of the overlapping parts will be omitted.

The CDMA signal radio waves composed of the direct wave 4 transmitted from the same radio wave source 3 shown in FIG. 6 and the plurality of reflected waves 6 reflected from each building 5 are linearly separated from each other as shown in FIG. The antennas 2a, 2b, 2
c, 2d. Antennas 2a, 2 for each channel
b, 2c, 2d radio frequency (RF) four C
The DMA signal is a P / S (parallel / serial) conversion circuit 2
1 is input.

The P / S conversion circuit 21 is configured, for example, as shown in FIG. A high frequency (RF) CDMA signal input from each of the antennas 2a to 2d is
The voltage is applied to the diode 21b in the forward direction via 1a.
The switch 21c is connected to the input terminal of the diode 21b.
A DC voltage + V is applied via. In a normal state, the signal level of the CDMA signal is lower than the forward voltage (0.6 V) of the diode 21b, so that the signal cannot pass through the diode 21b. And switch 2
1a, the bias point rises and C
The DMA signal passes through the diode 21b. Then, by closing and opening the switches of each channel in order with a clock signal (not shown), the CDAM of each channel is opened.
The signal is time-divided and incorporated into one serial signal a.

In this case, the closing time of the switch 21a of each channel, that is, the duration of the signal in one channel is set to twice the period of the PN signal obtained by spectrum-spreading the CDMA signal. That is, each time-divided signal always includes a PN signal for one cycle.

The high-frequency serial signal a output from the P / S conversion circuit 21 is converted to an intermediate frequency by the input RF interface 15 in the demodulator 35. The intermediate frequency serial signal a output from the input RF interface 15
₁ is converted into a pair of baseband signals I and Q by a demodulation unit 16. The pair of baseband signals I and Q output from the demodulation unit 16 in the demodulator 35 are converted into digital baseband signals I and Q having, for example, an 8-bit configuration by the A / D converter 22 and then converted to a high-speed FPGA (fast Input to a digital correlator 23 composed of a programmable gate array).

As shown, the digital correlator 23 composed of a high-speed FPGA has four high-speed RAMs 24 as a plurality of storage elements, one correlator 25, four partial waveform RAMs 26, And two correlation adders 27.

The four high-speed RAMs 24 constitute a kind of bank memory, and each high-speed RAM 24 has a storage capacity of, for example, 1 k words. And four high-speed RA
In each of the high-speed RAMs 24 in the M24, partial data corresponding to 1/4 of the digitized baseband signal for one channel that has been time-divided earlier is written.

The correlator 25 sequentially reads out the partial data of each of the four high-speed RAMs 24 in each of the four high-speed RAMs 24 and sequentially calculates the partial correlation characteristic between each of the read-out partial data and the PN signal. 4 waveform RAMs 26
Are sequentially written into the partial waveform RAMs 26 in.

FIG. 2 is a block diagram showing a detailed configuration of the correlation unit 25. The correlator 25 includes one 1k word register 28, 1000 EXNOR circuits 29, and a reference PN
It comprises a pattern memory 30 and a partial correlation adder 31.

The reference PN pattern memory 30 stores a P bit whose bit cycle is set to 1000 bits near (2 ¹⁰ -1).
It is composed of a shift register consisting of 1000 registers for storing each bit data of the N signal.

Each high-speed RA in the four high-speed RAMs 24
1k words read from M24, that is, 1000 pieces of 8-bit data, are written to the 1st to 1000th registers in the 1k word register 28. 8 constituting the partial data output from each register
Between the data of the bit configuration and the bit value of the PN pattern at the corresponding register position on the reference PN pattern memory 30
The EXNOR value is calculated by the EXNOR circuit 29.

The 1000 calculated values calculated by the 1000 EXNOR circuits 29 are added in the partial correlation adder 31 to form a single correlation value in the partial waveform memory 26 corresponding to the bank number of the high-speed RAM 24 in time series. Is memorized and held.

Next, the stored bit value of each register of the reference PN pattern memory 30 is moved by one register. Then, in this moved state, as described above, 1000
The EXNOR circuit 29 calculates 1000 EXNOR values and calculates
The 00 calculated values are calculated by the partial correlation adder 31, and stored as a single correlation value in the same partial waveform memory 26 in time series.

As described above, the reference PN pattern memory 30
The correlation values are written into the partial waveform memory 26 while the storage bit value of each register is shifted by one register.

When each register of the reference PN pattern memory 30 is cycled, each correlation value stored in the corresponding partial waveform memory 26 in a time series is arranged in a time series, so that the corresponding high speed RAM 24 in the corresponding high speed RAM 24 is arranged. A partial correlation characteristic of the stored partial data is obtained.

When the partial correlation characteristic b for the partial data stored in one high-speed RAM 24 is formed in the corresponding partial waveform memory 26, the high-speed RAM 2 of the next bank number
4 is written into the 1k word register 28, and while shifting each register of the reference PN pattern memory 30, the partial waveform memory 2 of the next bank number is shifted.
6, a partial correlation characteristic b of the corresponding partial data is created.

When the respective partial correlation characteristics b for all the partial data in the high-speed RAM 24 are formed in the respective partial waveform memories 26, the respective partial correlation characteristics formed in the respective partial waveform memories 26 by the correlation adder 27 are obtained. b is added to obtain a correlation characteristic c for one channel.

FIG. 4 is a waveform chart showing the operation of the correlation adder 27 which adds four partial correlation characteristics b to obtain one correlation characteristic c. Since each partial data is stored in each high-speed RAM 24 while being shifted in time series, when adding each partial correlation characteristic b, the addition is performed by shifting the time axis.

When the correlation characteristic c for one channel created by the correlation adder 27 is calculated, the correlation characteristic c
Is written into the waveform memory 32 once. This waveform memory 3
The correlation characteristic c for one channel written in 2 is transmitted to the D / A converter 34 of the corresponding channel via the S / P conversion circuit 33.
a (34b to 34d) and becomes an analog correlation characteristic d.

FIG. 5 shows the waveform (FIG. 5A) of the serial signal a ₁ after the frequency conversion to the intermediate frequency by the input RF interface 15 in the demodulator 35 (FIG.
Analog correlation characteristic d output from / A converter 34a
FIG. 6 is a comparison diagram showing a relationship with FIG. As described above, by using the digital correlator 23, the synchronization point for the PN signal can be easily specified.

In FIG. 2, for the sake of simplicity, the correlation calculation process for one of the pair of baseband signals I and Q demodulated by demodulator 16 in demodulator 35 will be described. Stated. However, in an actual circuit, both baseband signals I and Q are simultaneously processed in parallel. As a result, the correlation characteristic d of the analog output from the D / A converter 34a of each channel (34b~34d) correlation characteristic R _I corresponding to each baseband signals I, Q, the R _Q.

In FIG. 1, the conversion timing of the P / S conversion circuit 21 and the conversion timing of the S / P conversion circuit 33 are completely synchronized.
a, 2b, 2c, and 2d, analog correlation characteristics R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 , R _Q3 , R _I4 , R _I for each baseband signal corresponding to each CDMA signal. _Q4 is
D / A converters 34a for each corresponding channel,
It is output from 34b, 34c, 34d.

The correlation characteristics R _{I1 to} R _{Q4 for} each analog baseband signal output from each of the D / A converters 34a to 34d are stored and held in a data recorder (not shown). Thereafter, as shown in FIG. 8, in the analysis device 8 installed in the experimental analysis room, each of the correlation characteristics R _{I1 to} R _Q4 is reproduced, and the reproduced correlation characteristics R _{I1 to} R _Q4 are A / D converted. I do. Finally, the direction of the arriving radio wave is calculated from the A / D-converted correlation characteristics R _{I1 to} R _Q4 .

In the multi-channel correlation receiving apparatus thus configured, each CDMA signal received by each of the antennas 2a to 2d is converted into one serial signal a by the P / S conversion circuit 21, and the input RF interface 15 After demodulation, the demodulation unit 16 demodulates the signal into a pair of baseband signals I and Q. The demodulated pair of baseband signals I and Q are A / D-converted, and then converted into a digital correlator 23.
Is input to

The digital correlator 23 has a correlation characteristic R _I between data of one time-division channel of each baseband signal sequentially output from the A / D converter 22 and a PN signal used for spread spectrum. , _RQ are sequentially calculated. The correlation characteristics R _I and R _Q sequentially output from the digital correlator 23 are converted by the S / P conversion circuit 33 into correlation characteristics R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 , R _Q3 , R
_I4, is separated into R _Q4.

In this case, in the digital correlator 23,
The correlation characteristic R _I for one baseband signal I, Q,
The time required to calculate R _Q is 2 times of the PN cycle.
It is a power. Therefore, the time required for calculating the correlation characteristic can be significantly reduced as compared with the conventional analog correlator.

Specifically, the bit period of the PN signal is shown in FIG.
As shown in the reference PN pattern memory 30 of FIG. 5, when the signal speed (bit rate) of the CDMA signal is 30 Mbps, the digital correlator 23 uses the period of the PN signal of 2 as shown in FIG. The time required to calculate the correlation characteristic d with respect to the data (baseband signal) for one channel time-divided at a double cycle is about 5 ms.

Therefore, the time required to calculate the correlation characteristics R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 , R _Q3 , R _I4 , and R _Q4 for four channels is about 20 ms. Therefore,
As compared with about 0.2 seconds in the conventional multi-channel correlation receiving apparatus using the analog correlator 17 shown in FIG.
Can be reduced to zero.

In general, a digital correlator can be constructed in a software manner by using a CPU, but the correlation operation has a very large number of operation steps of the same type. For example, at the bit rate (transmission rate) of 30 Mbps described above, P
When the period of the N signal is 1023 (≒ 1000), the number of calculations for one channel is 1023 × 8, and the calculation time is about 20 ms. Therefore, when the number of channels is four, the calculation time is about 80 ms. Therefore, it is advantageous in terms of time to correlate the digital signal in a hardware manner as in the apparatus of the present embodiment.

[0067] Thus, by employing a digital correlator, if the baseband signal I of the four respective channels in one digital correlator 23, the correlation characteristic R _I for Q, the R _Q chronologically Even if you do it in order,
The time required to calculate the correlation characteristics for all the channels can be greatly reduced as compared with the conventional apparatus shown in FIG.

Accordingly, the number of demodulators and correlators can be limited to one each as the whole multi-channel correlation receiving apparatus, and the obtained correlation characteristics R _I1 , R _Q1 , R _I2 , R _Q2 , R _I3 ,
In R _Q3 , R _I4 , and R _Q4 , it is possible to prevent variations in measured values between channels. Further, since the correlation characteristics of almost the same arriving wave can be accurately measured, the arrival direction of the arriving wave can be calculated accurately.

The digital correlator 23 is composed of four high-speed RAMs 24, one correlator 25, four partial waveform memories 26, and one correlation adder 27. The correlator 25 calculates 1/4 of the time-divided channel.
Since the partial correlation characteristic b between the partial data of the PN signal and the data for one cycle of the PN signal may be calculated, the digital correlator is compared with a correlator that calculates the correlation characteristic c for all data for one channel at a time. 23 can be simplified. As a result, the circuit configuration of the entire multi-channel correlation receiving apparatus can be further simplified.

The present invention is not limited to the above embodiment. In the correlator 25 of the digital correlator 23 in the embodiment, as shown in FIG. 2, each bit data of the partial data inputted from each high-speed RAM 24 into the 1k word register 28 is fixed, and the reference PN pattern memory Thirty bit data are sequentially shifted. However, conversely, the bit data of the reference PN pattern memory 30 may be fixed, and each bit data of the partial data input into the 1k word register 28 may be sequentially shifted.

[0071]

As described above, in the multi-channel correlation receiving apparatus of the present invention, by using a digital correlator, one P / S conversion circuit and one S / P conversion circuit are used for each channel. One demodulator and one correlator are shared.

Therefore, it is not necessary to use a demodulator or a correlator for each channel, and the correlation characteristics of the same arriving wave can be accurately measured with a simple circuit configuration. The direction of arrival of each incoming wave can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a schematic configuration of a multi-channel correlation receiving apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a digital correlator incorporated in the multi-channel correlation receiving apparatus.

FIG. 3 shows a P / S incorporated in the multi-channel correlation receiver.
Block diagram showing the detailed configuration of the conversion circuit

FIG. 4 is a diagram showing an operation of adding a partial correlation characteristic in a correlation adder incorporated in a digital correlator of the multi-channel correlation receiving apparatus.

FIG. 5 is a diagram showing a comparison between a baseband signal waveform and a correlation characteristic in a digital correlator of the multi-channel correlation receiving apparatus.

FIG. 6 is a diagram showing a relationship between a test vehicle and an arrival direction of each arriving wave.

FIG. 7 is a block diagram showing a schematic configuration of a conventional multi-channel correlation receiving apparatus.

FIG. 8 is a schematic diagram showing an analysis device in a multi-channel multiplex wave phase difference measurement device.

FIG. 9 shows C incorporated in a conventional multi-channel correlation receiving apparatus.
FIG. 2 is a block diagram showing a detailed configuration of a DMA receiving unit.

FIG. 10 is a diagram showing a correlation characteristic between each baseband signal output from the CDMA receiving unit and a PN signal;

FIG. 11 is a correlation characteristic diagram of each channel.

FIG. 12 is a diagram showing the relationship between the correlation characteristics of each channel and the direction of arrival of radio waves.

FIG. 13 is a diagram showing the relationship between the correlation characteristics of each channel and the direction of arrival of radio waves.

FIG. 14 is a detailed block diagram of an input RF interface and a demodulator incorporated in a CDMA receiver of a conventional multi-channel correlation receiver.

[Explanation of symbols]

 2a, 2b, 2c, 2d antenna 15 input RF interface 16 demodulation unit 21 P / S conversion circuit 22 A / D conversion unit 23 digital correlator 24 high-speed RAM 25 correlation unit 26 partial waveform memory 27 ... Correlation adder 28 ... 1k word register 29 ... EXNOR circuit 30 ... Reference PN pattern memory 31 ... Partial correlation adder 32 ... Waveform memory 33 ... S / P converter 34a, 34b, 34c, 34d ... D / A converter 35 ... Demodulator

Continuation of the front page (72) Inventor Teruya Fujii 2-10-1 Toranomon, Minato-ku, Tokyo NTT Mobile Communications Network Co., Ltd. F-term (reference) 5K022 EE02 EE32 EE35

Claims (2)

[Claims] 1. A plurality of antennas (2a to 2d) spaced apart from each other for receiving a CDMA signal radio spectrum spread and orthogonally modulated by a PN signal, and a radio signal received by the plurality of antennas. A P / S conversion circuit (21) that converts each antenna into a time-divided serial signal using each channel as a channel, and demodulates the serial signal output from the P / S conversion circuit into a pair of baseband signals. A demodulator (35); and an A / D converter (22) for converting each baseband signal demodulated by the demodulator into a digital baseband signal.
And a digital correlator for sequentially calculating a correlation characteristic between time-divided data of each one channel in each baseband signal sequentially output from the A / D converter and a PN signal used for the spread spectrum. (23) and an S / P conversion circuit (34a to 34d) for converting each correlation characteristic sequentially output from the digital correlator into parallel data composed of a plurality of correlation characteristics for each channel. Receiver. 2. A plurality of antennas (2a to 2d) spaced apart from each other for receiving a CDMA signal radio spectrum spread and orthogonally modulated by a PN signal, and a radio signal received by the plurality of antennas. A P / S conversion circuit (21) that converts each antenna into a time-divided serial signal using each channel as a channel, and demodulates the serial signal output from the P / S conversion circuit into a pair of baseband signals. A demodulator (35); and an A / D converter (22) for converting each baseband signal demodulated by the demodulator into a digital baseband signal.
And a plurality of storage elements (24) for dividing time-divided data of each one channel in each baseband signal output from the A / D converter into a plurality of partial data and storing the divided data.
A correlation section (25) for sequentially calculating a partial correlation characteristic between each partial data stored in each storage element and the PN signal used for the spectrum spreading; and a section for each section sequentially calculated by the correlation section. A correlation adder (27) for calculating a correlation characteristic of each baseband signal for each channel by adding each partial correlation characteristic corresponding to data; and a correlation output sequentially output from the correlation adder for each channel. And a S / P conversion circuit (34a to 34d) for converting the data into parallel data having a plurality of correlation characteristics.