JPH06204979A - M-ary spread spectrum system communication equipment - Google Patents

Abstract

PURPOSE:To improve reception performance under phasing conditions by performing multipath delay wave synthesis diversity. CONSTITUTION:Transmission data are converted in to parallel data symbols by the data symbol unit of M-ary modulation at a serial/parallel conversion circuit 1 and PN codes corresponding to the data symbols are selected at a mapping circuit 2. A PN code generation circuit assembly 3 generates the PN codes, unique words for training are inserted at a unique word insertion circuit 5 and spreading is performed by the PN codes for discriminating channels from a PN code generation circuit 7 at a multiplier 6. Reception signals are converted into a base band and after inverse spreading, diversity synthesis is performed at a tapped delay line 15. The tap coefficient of the tapped delay line 15 is appropriately adjusted at an arithmetic circuit 18 based on the unique word. The transmission PN codes are judged for the output by respective correlation devices 20, made correspond to the data symbols at an inverse mapping circuit 21 and reproduced at a parallel/serial, conversion circuit 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication device using an M-ary spread spectrum method among parallel combination spread spectrum methods.

[0002]

2. Description of the Related Art In a spread spectrum communication system, a parallel combination spread spectrum communication system using a plurality of spread sequences can increase the information transmission rate several times or more for the same transmission band and the same processing gain. is there. One of the methods is the M-ary spread spectrum method. The M-ary spread spectrum method is a method of increasing the information transmission rate without degrading the processing gain by assigning different spreading sequences to the states of several bits of transmission data.

FIG. 3 shows the configuration of a conventional M-ary spread spectrum communication apparatus. FIG. 3A shows the configuration of the transmission unit, and FIG. 3B shows the configuration of the reception unit. In FIG. 3A, 1 is a serial / parallel conversion circuit (serial / parallel conversion circuit), 2 is a mapping circuit, and 3 is a PN code generation circuit assembly having a plurality of PN code generation circuits 4. Reference numeral 6 is a multiplier, and 7 is a PN code generating circuit for channel identification. 8 is a double balanced mixer, 9 is a transmission carrier generation circuit, and 10 is a transmission antenna. In FIG. 3B, 11 is a receiving antenna, 12 is a double balanced mixer, 13 is a local oscillation circuit, 14 is a correlator, 19 is a plurality of correlators, and a correlator assembly having 20. Reference numeral 21 is an inverse mapping circuit, and 22 is a parallel-serial conversion circuit (parallel-serial conversion circuit).

Next, the operation of the conventional M-ary spread spectrum communication apparatus will be described with reference to FIG. In the transmission unit shown in FIG. 3A, the transmission data arranged in time series is converted into M-ar by the serial-parallel conversion circuit 1.
The data symbols of y modulation are converted into parallel data symbols. Then, the mapping circuit 2 selects the PN code corresponding to each of the data symbols converted in parallel. These PN codes are respectively input to the PN code generating circuit 4, generate the PN code selected by the PN code generating circuit assembly 3, and are used for channel identification generated by another PN code generating circuit 7 in the multiplier 6. Is further spread by the PN code of No. 1, converted into a carrier band by the transmission carrier generation circuit 9 in the double balanced mixer 8, and transmitted from the antenna 10.

In the receiving section shown in FIG. 3B, the carrier wave received by the antenna 11 is converted into the baseband band by the double balanced mixer 12 and the local oscillation circuit 13, and the correlator 14 is used to convert the carrier wave into the baseband. Despreading is performed by obtaining the correlation with the PN code for channel identification generated by the PN code generation circuit of the transmission section shown in FIG. The output signal of the correlator 14 is input to each correlator 20 that constitutes the correlator assembly 19, and the mapping circuit 2 in the transmitter shown in FIG.
The correlator assembly 19 determines which PN code has been transmitted at, and the inverse mapping circuit 21 associates it with the data symbol. The parallel data symbol output from the inverse mapping circuit 21 is converted into serial data by the parallel / serial conversion circuit 22, and the same data as the transmission data is reproduced.

[0006]

However, in the above-mentioned conventional M-ary spread spectrum communication apparatus, when there is a multipath delayed wave due to fading or the like, the signal of the desired channel is received with a time difference due to time lag. Therefore, there is a problem that the signal of the desired channel has the same property as the other channels, the SN ratio is lowered, and the reception performance is deteriorated.

The present invention solves such a conventional problem, and provides an excellent M-ary spread spectrum communication apparatus capable of obtaining a good reception state even when a multipath delay wave due to fading is generated. The purpose is to provide.

[0008]

In order to achieve the above object, the present invention inserts a unique word into a PN code in a transmitter and delays a received signal despread by a correlator in a receiver with tap delay. Input to the line and use the tap coefficient of the tapped delay line using the unique word included in the received signal, and the arithmetic circuit is designed to minimize the error between the demodulated data in the unique word section and the bit pattern of the unique word. It has a function of synthesizing multipath delayed waves by performing calculation with an adaptive algorithm. In order to achieve another object, the transmitter uses a Walsh function as a PN code,
In the receiving part, a Hadamard transform is performed using a high-speed Hadamard converter.

[0009]

Therefore, according to the present invention, the transmitting section transmits the PN code including the unique word, and the receiving section operates the arithmetic circuit so that the demodulated data in the unique word section matches the bit pattern of the unique word. Since the tap coefficient of the tapped delay line is adjusted in accordance with the above, when multipath delay waves are generated due to fading or the like, diversity combining of the multipath delay waves is performed on the despread reception signal.

[0010]

(Embodiment 1) FIG. 1 shows the configuration of an M-ary spread spectrum communication apparatus according to a first embodiment of the present invention. Figure (a) shows the same as (b) of the transmitter.
Shows the configuration of the receiving section, respectively. In FIG.
The same parts as those of FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 1 (a),
Reference numeral 5 is a unique word insertion circuit inserted into the output side of the PN code generation circuit assembly 3 and the input side of the multiplier 6, and inserts a known word into the data to be transmitted. In FIG. 1B, reference numeral 15 is a delay line with a tap, which functions as a transversal filter. 16 is a serial-parallel conversion circuit,
A unique word detection circuit 17 detects a known word as a training signal. Reference numeral 18 denotes an arithmetic circuit, which performs an arithmetic operation of the adaptive algorithm.

Next, the operation of the M-ary spread spectrum communication apparatus according to the first embodiment will be described with reference to FIG. In the transmission unit shown in FIG. 1A, transmission data configured in time series is converted into parallel data symbols by the serial-parallel conversion circuit 1 in units of M-ary modulated data symbols. Then, the mapping circuit 2 selects the PN code corresponding to each of the data symbols converted in parallel. These PN codes are PN
The PN code input to the code generation circuit 4 and selected by the PN code generation circuit assembly 3 is generated. Next, the unique word insertion circuit 5 inserts a unique word which is predetermined information and which transmits a predetermined section at regular intervals. This unique word is for training adaptive algorithms. The PN code in which the unique word is inserted is further spread by the PN code for channel identification generated in another PN code generating circuit 7 in the multiplier 6, and is transmitted by the transmission carrier generating circuit 9 in the double balanced mixer 8. Converted to band, antenna 1
Sent from 0.

In the receiving section shown in FIG. 1B, the carrier wave received by the antenna 11 is converted into a baseband band by the double balanced mixer 12 and the local oscillation circuit 13, and the correlator 14 is used to convert the carrier wave to the baseband. Despreading is performed by obtaining the correlation with the PN code for channel identification generated by the PN code generation circuit of the transmission section shown in FIG. A multipath delay wave diversity combination is performed on the despread signal by the tapped delay line 15. The tap coefficient of the tapped delay line 15 is adaptively adjusted by the arithmetic circuit 18 based on the unique word synchronized by the unique word detection circuit 17. In order to perform this adjustment, the received data which is the output signal of the tapped delay line 15 is converted into parallel data by the serial-parallel conversion circuit 16 in the length of the unique word and input to the unique word detection circuit 17. Unique word detection circuit 17
The unique word that is the same as the unique word that is inserted in advance in the transmission unit is stored in, and the degree to which the stored unique word and the unique word in the received data converted in parallel coincide The unique word detection circuit 17 detects and outputs the output signal from the arithmetic circuit 1.
Enter in 8. That is, the unique word detection circuit 17
In accordance with the output signal of, the arithmetic operation is performed by an adaptive algorithm incorporated in the arithmetic circuit 18 so that the error between the demodulated data in the unique word section and the bit pattern of the unique word is minimized, and the tap coefficient of the tapped delay line 15 is calculated. adjust. The output signal of the tapped delay line 15 is input to each correlator 20 constituting the correlator assembly 19,
Which P in the mapping circuit 2 in the transmitter shown in FIG.
The correlator assembly 19 determines whether the N code is transmitted,
The inverse mapping circuit 21 associates with the data symbol.
The parallel data symbol output from the inverse mapping circuit 21 is converted into serial data by the parallel / serial conversion circuit 22, and the same data as the transmission data is reproduced.

As described above, according to the first embodiment, the unique word is inserted by the unique word insertion circuit 5 in the transmitting section, and the arithmetic circuit 18 in the receiving section causes the demodulated data in the unique word section and the bit pattern of the unique word. By adjusting the tap coefficient of the tapped delay line 15 so that the error between and is minimized, the tapped delay line 15 generates a multipath delay wave of the despread received signal. Since diversity combining is performed, there is an effect that a good reception state that is not affected by the multipath delay wave can be obtained.

(Embodiment 2) The second embodiment of the present invention is based on M
-Ary spread spectrum communication device, PN
The Walsh function is used as the code, and the correlation value is obtained by Hadamard transform in the receiving unit.

FIG. 2 shows the M- in the second embodiment of the present invention.
1 shows a configuration of an ary spread spectrum communication device. FIG. 2A shows the configuration of the transmitter, and FIG. 2B shows the configuration of the receiver. In FIG. 2, the first
Constituent elements having the same functions as the constituent elements in the embodiment are given the same reference numerals, and description thereof will be omitted. In FIG. 2, reference numeral 23 is a Walsh function generation circuit aggregate, 24 is a Walsh function generation circuit, 25 is a serial-parallel conversion circuit, and 26 is a fast Hadamard converter (FHT).

Next, the operation of the M-ary spread spectrum communication apparatus in the second embodiment will be described with reference to FIG. In the transmission unit shown in FIG. 2A, the mapping circuit 2 selects the Walsh functions corresponding to the data symbols converted in parallel by the serial / parallel conversion circuit 1. These Walsh functions are divided into a high alternating number and a low alternating number and are input to the Walsh function generating circuit 24, and the Walsh function generating circuit assembly 23 generates the selected Walsh function. The subsequent operation in the transmitting unit is the same as that in the first embodiment, and the Walsh function in which the unique word is inserted is further processed by the PN code for channel identification generated by the PN code generating circuit 7 in the multiplier 6. The signal is spread, converted into a carrier band by the transmission carrier generation circuit 9 in the double balanced mixer 8, and transmitted from the antenna 10.

In the receiving section shown in FIG. 2B, since the receiving antenna 11 receives the carrier wave, the tap coefficient of the tapped delay line 15 is adjusted to perform diversity combining of the multipath delayed waves. Is the same as the operation in the first embodiment. The output signal of the tapped delay line 15 is input to the serial / parallel conversion circuit 25.
In the serial-parallel conversion circuit 25, in order to carry out the correlation of the Walsh function so that the output signal of the tapped delay line 15 can be subjected to the Hadamard conversion, the received data of one cycle of the Walsh function is converted into the high-speed Hadamard converter. Convert to parallel data as input to 26. When the Walsh function is used for the spread code of the M-ary spread spectrum system, the high-speed Hadamard converter 26 receives the received data in synchronization with the cycle of the Walsh function in the receiving unit.
Need to enter. Therefore, in order to perform serial-parallel conversion in synchronization with the timing of one cycle of the transmitted Walsh function, the output signal of the unique word detection circuit 17 is input to the serial-parallel conversion circuit 25 as a clock for synchronization. In order to synchronize the high-speed Hadamard converter 26, the output signal of the unique word detection circuit 17 is input to the high-speed Hadamard converter 26 as a clock for synchronization. In this way, the output signal of the unique word detection circuit 17 can be used for synchronizing the Walsh function. As described above, the received data that has been Hadamard-transformed by the high-speed Hadamard converter 26 is associated with the data symbol in the inverse mapping circuit 21, and the inverse mapping circuit 21
The parallel data symbol output from is converted into serial data by the parallel / serial conversion circuit 22, and the same data as the transmission data is reproduced.

As described above, according to the second embodiment, M
-A high-speed Hadamard converter 2 is used in the receiving section by using a Walsh function as a spread spectrum spread code.
Since the Hadamard transform is performed by 6, the amount of calculation in the receiver is significantly smaller than that in the case where the correlator assembly 19 is used, and there is an effect that both the shape and the power consumption of the receiver are reduced.

[0019]

As is apparent from the above-described embodiments, the present invention is provided with a unique word insertion circuit in the transmitting section in the M-ary spread spectrum communication apparatus to insert the transmission data unique word, and the receiving section is tapped. A delay line and an arithmetic circuit are provided, and the arithmetic circuit performs an arithmetic operation by an adaptive algorithm so as to minimize the error between the demodulated data in the unique word section and the bit pattern of the unique word, and adjusts the tap coefficient of the tapped delay line. As a result, the multipath delay waves are diversity-combined by the tapped delay line with respect to the despread signal, so that even if a multipath delay plate is generated due to fading, it is not affected by the multipath delay waves. It has an effect that a good reception state can be obtained.

Further, according to the present invention, since the Walsh function is used in the transmitting unit and the Hadamard transform is performed in the receiving unit, the receiving unit having a small size and low power consumption is not affected by the multipath delay wave and has a good reception state. Has the effect of being obtained.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of an M-ary spread spectrum communication device according to a first embodiment of the present invention. (A) is a transmitter (b) is a receiver

FIG. 2 is a schematic block diagram of an M-ary spread spectrum communication device according to a second embodiment of the present invention, where (a) is a transmitter and (b) is a receiver.

FIG. 3 is a schematic block diagram of a conventional M-ary spread spectrum communication device (a) is a transmitter (b) is a receiver.

[Explanation of symbols]

 5 Unique Word Insertion Circuit 15 Delay Line with Tap 17 Unique Word Detection Circuit 18 Arithmetic Circuit 23 Walsh Function Generating Circuit Assembly 24 Walsh Function Generating Circuit 26 High Speed Hadamard Converter

Claims (2)

[Claims] 1. A transmitter includes a unique word insertion circuit for inserting a unique word, which is known data, into a PN code, and a receiver includes a delay line with a tap for delaying a despread reception signal and a pre-stored delay line. A unique word detecting circuit for comparing and detecting the unique word contained in the received signal and a unique word section of the stored unique word and the received signal by the output signal of the unique word detecting circuit. M-ar including an arithmetic circuit for adjusting the tap coefficient of the tapped delay line by performing an arithmetic operation by an adaptive algorithm so as to minimize an error from the output signal of the tapped delay line.
y Spread spectrum communication device. 2. A Walsh function is used as the PN code,
The M-ary spread spectrum communication device according to claim 1, wherein demodulation is performed by high-speed Hadamard conversion in the receiving unit.