JP2000353978A - Demodulator and demodulation method in cdma communication - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform multicode reception more than two codes by equipping a finger circuit corresponding to a propagation path with a selection means for selecting a PN code generation means that is different according to PN code selection signals and an inverting diffusion means for extracting a transmission signal which multiplies a code corresponding to the PN code out of reception signals. SOLUTION: In a finger circuit 4, a PN code is outputted from PN code generation means 14b1 to 14b3. In this state, it is possible to detect codes 1, 2 and 3 once for each from reception signals received at the finger circuit 4 by switching a selection switch 14e on the basis of a PN code selection signal supplied with a time interval (t) from outside and supplying the PN code from the PN code generation means 14b1 to 14b3 to a successive multiplying means 14a. Then, a code which is inverting diffused by way of a successive integration discharge means 14c and detected is supplied to a detection means 14d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a demodulation apparatus and a demodulation method in CDMA communication in which a transmission signal multiplied by a different code for each user and each radio channel is multiplexed and transmitted in a frequency bandwidth wider than the transmission signal band. It is about.

[0002]

2. Description of the Related Art FIG. 4 is a model diagram for transmitting a signal from a transmitting station 101 to a receiving station 102, and a direct propagation path 103 for directly transmitting a transmission signal from the transmitting station 101 to the receiving station 102.
In addition, there are delay propagation paths 104 and 105 that propagate while reflecting on obstacles such as buildings and mountains. The transmission signal is a signal multiplexed with a plurality of codes including a code to be received.

Therefore, conventionally, in order to improve the receiving accuracy, in addition to the finger circuit as the receiving means for receiving the transmission signal through the direct propagation path 103, the transmission signal through the delay propagation paths 104 and 105 is received. A finger circuit as a receiving means, and each of the propagation paths 103 to 10
5 is implemented in the CDMA communication that rake-combines and receives the transmission signal.

FIG. 5 is a block diagram showing a conventional demodulator for CDMA communication employing Rake reception.
11, a receiving circuit having a receiving antenna 112; 113, an analog / digital (hereinafter abbreviated as A / D) converting circuit for converting an analog signal, which is a received signal output from the receiving circuit 111, into a digital signal; Numeral denotes finger circuits provided in the same number as the codes to be received multiplexed in the transmitting station 101. The finger circuits 114 are multiplying means 114a1-11 for inputting received signals corresponding to the propagation paths 103-105, respectively.
4a3, a PN code generating means 114b for providing the multiplying means 114a1 to 114a3 with a PN code for despreading the code contained in the transmission signal, and the multiplying means 114a1
Discharging means 114c1 for inputting the outputs of .about.114a3
To 114c3, the integral discharge means 114c1 to 114c.
3 and detecting means 114d1 to 114d3 for detecting the output of No. 3 and supplying it to the combiner circuit 117.
Since the other finger circuits 115 and 116 have the same configuration, the detailed configuration is omitted. The output is input to combiner circuits 118 and 119. The multiplying means and the integrating discharge means constitute a reverse diffusion means. The finger circuit 114 outputs the result of the Rake synthesis demodulation of the code 1, and the combiner circuits 118 and 119 output the Rake synthesis demodulation of the codes 2 and 3.
An e-combined demodulation result is obtained.

Next, the operation will be described. Transmitting station 101
Are transmitted from the receiving antenna 112 to the receiving circuit 111 in sequence.
After being converted into a digital signal by the A / D conversion circuit 113, the digital signal is input to the multiplication means 114a1 to 114a3 of each finger circuit 114 (to 116). Hereinafter, since the finger circuits 115 and 116 operate in the same manner as the finger circuit 114, the description will be omitted. In the multiplication means 114a1 to 114a3 in the finger circuit 114, the propagation path 1
PN code generating means 114 according to the delay amount
b, multiplying the received signal by the PN code sequentially output from b, performs despreading via the integration discharge means 114c1, and performs code 1
コ ー ド code 3 is multiplied and the transmitted signal is detected. Then, the detected transmission signal is detected by the detection means 114d1.
, And the detection signal is supplied to the combiner circuit 117. Next, the transmission signal transmitted by the delay propagation path 104 with a predetermined time delay
, And is converted into a digital signal by the A / D conversion circuit 113, and then input to each finger circuit 114.

Then, the multiplication means 114a1 to 114a3 of each finger circuit 114 apply
Despreading is performed by multiplying by the PN code output from the N code generating means 114b, and the finger circuit 114 detects a transmission signal multiplied by the codes 1 to 3 and transmitted.
The detected transmission signal is input to the detection means 114d1 via the integration discharge means 114c1, and the detection signal is supplied to the combiner circuit 117. Further, the transmission signal transmitted with a delay of a predetermined time by the delay propagation path 105 enters the receiving circuit 111 from the receiving antenna 112, and is converted into a digital signal by the A / D conversion circuit 113. The received signal corresponding to code 1 is the combiner circuit 1
17 is output. On the other hand, as described above, the finger circuits 115 and 116 extract the reception signals corresponding to the codes 2 and 3 and output the signals to the combiner circuits 118 and 119.

[0007]

Since the conventional demodulator for multi-code multiplexed CDMA communication is constructed as described above, the required number of finger circuits is the same as the number of multiplexed codes and the propagation for Rake combining. It is the product of the number of passes. For this reason, there has been a problem that the conventional receiving apparatus supporting multi-code requires an extremely large number of finger circuits.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a demodulator and a demodulator in CDMA communication capable of receiving multicodes of two or more codes without increasing the circuit scale and control amount. The aim is to get the method.

[0009]

Means for Solving the Problems CDMA according to the present invention
The demodulation device in the communication is one corresponding to one propagation path.
The finger circuit includes a selection means for selecting different PN code generation means according to a PN code selection signal, and a P signal from the selected PN code generation means.
Despreading means for extracting a transmission signal obtained by multiplying the received signal by the code corresponding to the PN code from the N code.

A demodulator for CDMA communication according to the present invention includes a plurality of finger circuits corresponding to a plurality of propagation paths having different delay times.

The demodulation device for CDMA communication according to the present invention performs despreading by each PN code a plurality of times in one chip.

A demodulation method in CDMA communication according to the present invention receives a transmission signal transmitted by a propagation path by multiplexing a transmission signal multiplied by a code different for each user into a frequency bandwidth wider than a band of the transmission signal. The received signal is input to the despreading means of one finger circuit, a different PN code is selectively applied to the despreading means by a PN code selection signal, and the selected PN code is multiplied by the corresponding code. This is to extract the signal.

[0013] In the demodulation method in CDMA communication according to the present invention, a transmission signal multiplied by a different code for each user is multiplexed into a frequency bandwidth wider than the bandwidth of the transmission signal and transmitted through a plurality of propagation paths having different delay times. The transmission signal received is input to the despreading means of the finger circuit corresponding to each propagation path, and a different PN code is selectively applied to the despreading means according to the PN code selection signal. A transmission signal obtained by multiplying the PN code and the corresponding code is extracted, and transmission signals of the same code output from the despreading means of each finger circuit are combined.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 shows C according to Embodiment 1 of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a demodulation device in DMA communication. In FIG. 1, reference numeral 1 denotes a receiving circuit having a receiving antenna 2, and 3 denotes an analog / digital (hereinafter abbreviated as A / D) converting circuit for converting an analog signal, which is a received signal output from the receiving circuit 1, into a digital signal. , 4 to 6 are direct propagation paths 103 and delay propagation paths 104 and 105, respectively.
The finger circuit 4 receives the transmission signal transmitted through the direct propagation path 103, and the finger circuit 5 transmits the transmission signal transmitted through the delay propagation path 104 into the finger circuit 6. Input the transmission signals transmitted by the delay propagation path 105, respectively.

Since the finger circuits 4 to 6 have the same configuration, the configuration of the finger circuit 4 will be described. The finger circuit 4 includes a multiplying means (despreading means) 14a for inputting a received signal corresponding to the propagation path 103, and a PN code for generating a PN code for inversely converting a code included in the transmission signal into the multiplying means 14a. Generating means 14b1 to 14b
3. Integral discharging means (despreading means) 14c for inputting the output of the multiplying means 14a, detecting means 14d for detecting the integrated discharging means 14c and supplying it to the combiner circuit 17, and PN code generating means 14b1 to 14b3. A selection switch (selection means) 14e for selecting a code based on a PN code selection signal supplied from the outside and providing the selected code to the multiplication means 14a.

FIG. 2 shows PN code generating means 14b1 to 14b.
FIG. 3 is a diagram showing a switching timing of No. 3, in which a PN code is generated corresponding to one chip of a PN phase of a received signal.

Next, the operation will be described. Received signals transmitted by the direct propagation path 103 and the delay propagation paths 104 and 105 delayed by the time τ1 and τ2 with respect to the direct propagation path enter the receiving circuit 1 from the receiving antenna 2 and
After being converted into a digital signal by the A / D conversion circuit 3, it is supplied to each of the finger circuits 4, 5, and 6.

First, in the finger circuit 4, PN codes are output from the PN code generating means 14b1 to 14b3 in the same phase corresponding to one chip of the PN phase of the received signal. In this state, the selection switch 14e is switched based on a PN code selection signal supplied from the outside at a time interval t (time interval obtained by dividing one chip into three), and the PN code is switched.
By sequentially supplying the PN codes from the code generation means 14b1 to 14b3 to the multiplication means 14a, the finger circuit 4
The codes 1, 2, and 3 can be detected once each from the received signal received as shown in FIG.

Then, the detected codes are sequentially despread via the integrating and discharging means 14c and supplied to the detecting means 14d. The detecting means 14d supplies the supplied code to the combiner circuit 17 and stores it in an adding means (not shown) for each code.

On the other hand, when the delay propagation path 104 is delayed from the direct propagation path 103 by the time τ1, the delay switch τ1 is supplied to the selection switch 14e in addition to the PN code selection signal supplied from the outside at the time interval t. By doing so, the PN codes from the PN code generating means 14b1 to 14b3 are supplied to the multiplying means 14a of the finger circuit 4 with a delay of τ1 from the above case, and the codes 1, 2, The signal of No. 3 is sequentially supplied to the detection means 14d via the integration discharge means 14c. The detecting means 14d supplies the supplied signals of the codes 1, 2, and 3 to the combiner circuit 17 and stores the signals for each of the stored codes.

Similarly, when the delay propagation path 105 is delayed from the direct propagation path 103 by a time τ2, this delay time τ2 is supplied to a selection switch 14e in addition to a code selection signal supplied from the outside at a time interval t. By doing so, the PN codes from the PN code generating means 14b1 to 14b3 are supplied to the multiplying means 14a of the finger circuit 4 with a delay of τ2 from the above case, and the codes 1, 2, The signal of No. 3 is sequentially supplied to the detection means 14d via the integration discharge means 14c. The detecting means 14d supplies the supplied signals of the codes 1, 2, and 3 to the combiner circuit 17 and stores the signals for each of the stored codes.

As described above, according to the first embodiment, the received signals accumulated in the adding means of the combiner circuit 17 are rake-combined with the received signals of the same code, and
By taking out as ake synthesis demodulation, the circuit scale,
Multi-code reception of two or more codes can be performed without increasing the control amount, and reception accuracy can be improved.

Embodiment 2 FIG. In the first embodiment, P
Within one chip of N phases, each code is despread once, but as shown in FIG. 3, the period of the PN code selection signal is shortened to 1/2, 1/3, etc. In this case, the number of times of despreading is increased to twice (two times in FIG. 3) and three times for each code, and each code detected by each despreading is added to improve the reception accuracy. Can be planned.

[0024]

As described above, according to the present invention, a finger circuit is assigned to each propagation path, and the PN code is given to the despreading means of this finger circuit by time division. , The size of the circuit can be reduced, and the amount of control can be reduced. Further, since the timing (phase) of each code transmitted on the same propagation path is common, even if the above-described time division processing is performed, there is an effect that the control of the finger circuit is very simple.

Also, since the despreading is performed twice or more for each code within the timing of one chip of the PN phase, the number of times of code detection is increased and the receiving accuracy can be improved. effective.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a demodulation device in CDMA communication according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing a switching timing of a PN code generating means.

FIG. 3 is a diagram showing another switching timing of the PN code generating means.

FIG. 4 is a model diagram for transmitting a signal from a transmitting station to a receiving station.

FIG. 5 is a block diagram illustrating a configuration of a demodulation device in conventional CDMA communication.

[Explanation of symbols]

4 to 6 finger circuits, 14a multiplication means (despreading means), 14b1 to 14b3 PN code generation means, 14c
Integral discharge means (reverse diffusion means), 14e selection switch (selection means), 103-105 Propagation path.

Claims (5)

[Claims] 1. A demodulation apparatus in CDMA communication for transmitting a transmission signal obtained by multiplying a transmission signal multiplied by a different code for each user and each radio channel into a frequency bandwidth wider than a band of the transmission signal corresponds to one propagation path. A finger circuit for selecting a different PN code generating means according to a PN code selection signal; and a PN code from the selected PN code generating means.
A despreading means for extracting a transmission signal obtained by multiplying the received signal by the code corresponding to the PN code from the received signal, comprising: a demodulation device for CDMA communication. 2. The demodulation apparatus according to claim 1, further comprising a plurality of finger circuits corresponding to a plurality of propagation paths having different delay times. 3. The C according to claim 1, wherein despreading by each PN code is performed a plurality of times within one chip.
Demodulation device in DMA communication. 4. A transmission signal obtained by multiplying a transmission signal multiplied by a different code for each user and each radio channel into a frequency bandwidth wider than a band of the transmission signal, receiving a transmission signal transmitted by a propagation path, A signal is input to the despreading means of one finger circuit, a different PN code is selectively applied to the despreading means by a PN code selection signal, and a transmission signal obtained by multiplying the selected PN code by the corresponding code is extracted. A demodulation method in CDMA communication. 5. A transmission signal obtained by multiplying a transmission signal multiplied by a different code for each user and each radio channel into a frequency bandwidth wider than a band of the transmission signal to receive a transmission signal transmitted through a plurality of propagation paths having different delay times. Then, the received signal is input to the despreading means of the finger circuit corresponding to each propagation path, and a different PN code is selectively applied to the despreading means according to the PN code selection signal, and the corresponding PN code corresponding to the selected PN code is applied. A CD characterized by extracting a transmission signal multiplied by the code, and synthesizing transmission signals of the same code output from the despreading means of each finger circuit.
Demodulation method in MA communication.