JPH08163084A - Code division multiplex communication equipment - Google Patents

Abstract

PURPOSE: To improve data transmission efficiency by providing a comparator means comparing a reference with an output of any correlation device among plural correlation devices conducting correlation demodulation to information channels so as to eliminate the need for a delimiter for a start frame in a data stream. CONSTITUTION: An A/D converter 201 converts a base band multiplex signal into digital data and a digital correlation device 202 applies correlation demodulation to each information channel. Then a comparator means 205 is connected to an output of a correlation device 202 and compares its correlation output with a reference value. Whether or not modulation data are in existence in a concerned information channel, that is, whether or not an information signal is received is discriminated by providing the comparator means 205 comparing the correlation output with a threshold level in this way. The comparator means 205 does not discriminate reception data symbol but, discriminates reception signal power.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous code division multiplex communication device for increasing the information transmission speed by multiplexing a plurality of different spread codes having a small cross-correlation value in spread spectrum communication. It is a thing.

[0002]

2. Description of the Related Art Conventionally, in spread spectrum communication, there is a code division multiplex communication system which multiplexes a plurality of communication paths in the same band by utilizing a cross-correlation characteristic of a low spread code to increase an information transmission speed. As a technique related to a synchronous code division multiplex communication device using phase shift modulation, there is a proposal in Japanese Patent Application No. 5-151219, for example.

In such a code division multiplex communication system, a transmitter transmits a preamble spread in spectrum by a single spread code for a certain period of time prior to an information signal in order to acquire synchronization at a receiver, and thereafter. In some cases, a multiplexed information signal may be transmitted.

FIG. 5 is a block diagram showing the structure of a demodulator of a receiver in a conventional code division multiplex communication device.

This demodulator has the same number of correlators 2 as the number of multiplexed units.
02, and after the synchronization is established by receiving the preamble, the multiplexed data of each information channel is subjected to correlation demodulation. At this time, for example, when the reception multiplexed data at the time of performing the correlation operation is represented by a positive / negative signed binary number expression, the code bit of the correlator output can be regarded as the demodulated data in the two-phase phase modulation.

The parallel-serial conversion means 203 converts the plurality of parallel data thus correlated and demodulated into a high-speed serial data stream.

Generally, in order to recognize the start of a valid data in such a data stream, conventionally, a start frame delimiter (SFD) having a specific bit pattern is inserted in the data stream, and by this appearance, Measures have been taken to inform the receiver of the start of a legitimate information signal.

[0008]

However, inserting the SFD in the data stream as described above results in:
This causes a decrease in data transmission efficiency, and particularly in packet type data transmission, such a reduction in efficiency is remarkable.

Therefore, an object of the first invention relating to the present application is to provide a code division multiplex communication device which does not require SFD in a data stream and has high data transmission efficiency.

Further, an object of the second invention relating to the present application is to obtain the same effect as that of the first invention even when the transmission characteristic of the communication path is poor.

[0011]

A first aspect of the present invention (claim 1) relates to any one correlator output among a plurality of correlators for performing correlation demodulation on an information channel. Then, a comparison means for comparing the output value with a certain reference value is provided.

The second invention relating to the present application (claims 2 and 3) is to provide a comparator for any two or more correlation outputs among the plurality of correlation outputs, and It is characterized in that a majority decision means for making a majority decision with respect to the comparison decision signal is provided.

In both configurations, the comparison means performs an operation of comparing the received signal power of the information channel with a reference value and outputting the comparison determination signal.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment of the first invention relating to the present application.

In the figure, an analog / digital converter 201 is for converting a baseband multiplexed signal into digital data, and a correlator 202 is a digital correlator for performing correlation demodulation of each information channel. Also,
The comparison means 205 is connected to the output of one correlator 202 and compares the correlation output with a reference value.

In this embodiment, the case where the code division multiplexed baseband signal is converted into digital data and the correlation demodulation is performed by the digital correlator is taken as an example. here,
For example, if the correlator output signal is represented by an 8-bit positive / negative signed binary number, the correlation output obtained by the correlation calculation is a value from −128 to 127, as shown in FIG. By referring to the bit, the modulated data symbol of the information channel can be demodulated.

On the other hand, when there is no signal spectrum-spread by the spread code assigned to the information channel, such as during reception standby or preamble reception, that is, the information channel does not have sufficient received signal power. In this case, the correlator output is near 0.

Therefore, by providing a comparing means 205 for comparing the correlation output with a certain threshold value, it is determined whether or not modulated data exists in the information channel, that is, whether or not an information signal is received. You can Here, it is a feature of the present invention that these comparing means perform an operation of determining the received signal power, not the received data symbol.

FIG. 2 is a block diagram showing a concrete configuration example of the comparison means 205, and FIG. 3 is an explanatory view showing the operation of the comparison means 205 with respect to the output of the correlator 202.

Here, when the output of the correlator 202 is from -16 to 15, it is assumed that the receiver does not receive the information signal.

Further, as shown in FIG. 3, the correlator output is 1
If 6 or more or -17 or less, multi-input OR
The outputs of the gate 301 and the multi-input NAND gate 302 both become Hi. Therefore, the 2-input AND in FIG.
The determination signal from the output of the gate 303 becomes Hi, the received signal power is higher than a certain level, and it can be recognized that valid information data has been received.

On the other hand, when the correlator output is -16 or more and 15 or less, the multi-input OR gate 301 or the multi-input NAN is used.
One of the outputs of the D gate 302 becomes Low,
The determination signal output from the 2-input AND gate 303 is Lo
Since it is w, the received signal power is below a certain level,
It can be recognized that the demodulated data is invalid.

By detecting the rising of the control signal by the operation of the comparing means 205 as described above, it is possible to know the start of the information data in the data stream.

FIG. 4 is a block diagram showing an embodiment of the second invention relating to the present application.

In the figure, an analog / digital converter 201 is for converting a baseband multiplexed signal into digital data, and a correlator 202 is a digital correlator for performing correlation demodulation of each information channel. Also,
The comparison means 205 is connected to the outputs of the three correlators 202 and compares each correlation output with a reference value. Further, the majority decision judging means 206 is connected to the output of each of the three comparing means 205, and judges the comparison result by the majority decision from the output value of each comparing means 205.

Generally, in a wireless communication system, the correlator output has some deviation from the theoretical value due to the deterioration of the transmission line characteristics, noise, or the influence of the non-linearity of the transmission system. Especially when the transmission line characteristic is poor, there is a possibility that the determination signal by one comparing means 205 does not operate correctly as in the first embodiment.

Therefore, in the present embodiment, the comparison means shown in the first embodiment compares the outputs of a plurality of correlators with a reference value. In an ideal transmission path state, all of the plurality of comparison means 205 are in the reception standby mode, the preamble reception mode, and the information signal reception mode.
The judgment signal is generated by performing the same operation as in the first embodiment. However, even if some of the determination signals for receiving the plurality of information signals have an unstable operation due to the influence of the transmission line state as described above, the majority determination is performed on the outputs of all the comparison means. It is possible to prevent the judgment signal from erroneous operation by using the output signal as the information signal reception judgment signal, and to correctly receive the information signal as in the first embodiment. It becomes possible to recognize.

The method of obtaining the judgment signal from the comparison results of the plurality of comparison means 205 is not limited to a simple majority decision, and it is possible to apply, for example, the judgment by referring to the comparison results with different reference values. Is.

In each of the above embodiments, digital correlation demodulation is taken as an example, but even if an analog demodulator is used, the present invention can be implemented by a comparison means that performs an operation equivalent to that of this embodiment. Is.

[0030]

As described above, according to the first invention (Claim 1) of the present application, it is possible to determine whether or not the signal being received is an information signal in code division multiplex communication. , The SFD in the data stream becomes unnecessary,
Information transmission efficiency can be improved. In particular, this effect is great for packet-type data transmission.

According to the second invention (Claims 2 and 3) related to the present application, the determination signal can be obtained by the configuration according to the first invention due to the poor transmission quality of the communication path and the influence of noise. Even if there is a possibility that the error will not occur, it is possible to prevent an error in the decision signal by referring to the plurality of correlator outputs, and to obtain the same effect as the first invention.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a second invention related to the present application.

FIG. 2 is a block diagram showing a configuration example of a comparison means of the above embodiment.

FIG. 3 is an explanatory diagram showing the operation of the comparing means with respect to the correlator output of the above embodiment.

FIG. 4 is a block diagram showing an embodiment of a second invention relating to the present application.

FIG. 5 is a block diagram showing a configuration of a demodulator of a receiver in a conventional code division multiplexing communication device.

[Explanation of symbols]

 201 ... Analog-digital converter, 202 ... Digital correlator, 203 ... P / S converter, 204 ... Code generator, 205 ... Comparison means, 206 ... Majority decision means.

Claims (3)

[Claims] 1. A synchronous code division multiplex communication device that multiplexes a communication path by using a plurality of different pseudo-random sequences as spreading codes to increase an information transmission speed, and a fixed period before the multiplexed information transmission. In a code division multiplex communication device that transmits a spread spectrum signal with a single spread code as a preamble for acquisition of synchronization, the receiver includes a plurality of correlators that demodulate a plurality of multiplexed information signals, A code division multiplex communication apparatus comprising: a comparison unit that compares the signal power of the information channel with a reference value for one correlator output of the plurality of correlators. 2. A synchronous code division multiplex communication device that multiplexes a communication path by using a plurality of different pseudo-random sequences as spreading codes to increase an information transmission speed, and a predetermined period before transmission of multiplexed information. In a code division multiplex communication device that transmits a spread spectrum signal with a single spread code as a preamble for acquisition of synchronization, the receiver includes a plurality of correlators that demodulate a plurality of multiplexed information signals, With respect to two or more correlator outputs of the plurality of correlators, a plurality of comparing means for respectively comparing the signal power of the information channel with a reference value and a comparison result are determined from outputs of the plurality of comparing means. A code division multiplex communication device comprising: a determining unit. 3. The code division multiplex communication device according to claim 2, wherein the determination unit is a unit that determines the output of each comparison unit by a majority decision.