JPH04351129A - Spread spectrum communication equipment - Google Patents

Abstract

PURPOSE:To allow the communication equipment to be compatible with both the individual calling and the simultaneous calling and to reduce the circuit scale in the communication equipment used for the code split multiple access system. CONSTITUTION:A specific pseudo random (PN) code is allocated to the equipment and a common PN code is allocated thereto and when the a spread spectrum reception signal is received, deciding sections 36-42, 46 decide that the spread spectrum reception signal is subjected to spread spectrum by the specific PN code or the common PN code and send a deciding signal. A selection section 47 outputs selectively the specific PN code or the common PN code in response to the deciding signal as a reception reference PN code. Then demodulation sections 44, 49 demodulate the spread spectrum reception signal into a demodulation data based on the reception reference PN code.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a spread spectrum communication device, and in particular to code division multiple access (CDMA) which allocates a common receiving carrier frequency to a plurality of stations and allocates pseudorandom codes (PN codes) to perform multiple access. ) is concerned with a spread spectrum communication device.

0002

2. Description of the Related Art Generally, in a code division multiple access system, a common reception carrier frequency is assigned to a plurality of stations, and a unique PN code is assigned to each station. In such a code division multiple access system, the transmitting side spreads the spectrum of a data signal using, for example, a PN code to generate a transmission data signal, modulates a transmission carrier wave with this transmission data signal, and sends it out as a spread spectrum signal. There is. On the other hand, on the receiving side, upon receiving the spread spectrum signal, a so-called synchronization acquisition circuit performs synchronization acquisition on the received signal spread by the own station PN code, obtains a synchronization acquisition output signal, and transmits the own station P in a so-called synchronization tracking circuit.
After initializing the N code generator (reference PN code) using a synchronization acquisition output signal, synchronization tracking of the local station PN code is performed. In other words, it identifies the line to its own station.

0003

[Problems to be Solved by the Invention] As mentioned above, in the conventional code division multiple access system, each data signal is spread spectrum using a unique PN code. It is not possible to perform bulk calls. On the other hand, if the above-mentioned local station PN code is prepared as a reference PN code, and a collective paging PN code common to each station is prepared, and the local station PN code and the collective paging PN code are switched as necessary. , at the moment when the spread spectrum signal spread by the collective calling PN code is received, each station changes the reference PN code to the collective calling PN.
Switching to a code is extremely difficult. Furthermore, if each station is configured not only to have a synchronization acquisition circuit and a synchronization tracking circuit that correspond to its own station PN code, but also to have a synchronization acquisition circuit and a synchronization tracking circuit that correspond to the PN code for bulk paging, the reception system will be divided into two. There is a problem that a system is required and the circuit scale becomes large. An object of the present invention is to provide a spread spectrum communication device that can perform bulk calling without increasing the circuit scale.

0004

[Means for Solving the Problems] According to the present invention, a plurality of stations are provided, each station is assigned a unique PN code, and a code division multiple access method is adopted in which code division multiple access is performed between the stations. In a spread spectrum communication device that transmits a spread spectrum transmission signal and receives a spread spectrum reception signal, a common P common to all of the stations is used.
N codes are assigned, and a first selection means selectively outputs any one of the unique PN codes and the common PN code as a transmission reference PN code; transmitting means for performing spectrum spreading using the spread spectrum transmission signal and transmitting it as the spread spectrum transmission signal; a second selection means for selectively outputting the unique PN code and the common PN code as reception reference PN codes according to the determination signal; A spread spectrum communication device is obtained, comprising a demodulating means for demodulating the spread spectrum reception signal based on a reception reference PN code.

[0005]

[Operation] In the present invention, a unique PN code and a common PN code are provided, and the unique PN code or the common PN code is used as the reception reference PN code depending on whether the spread spectrum received signal is spread with the unique PN code or the common PN code. Since the spread spectrum reception signal is demodulated based on this reception reference PN code, it is possible to handle both individual paging and collective paging without increasing the circuit size.

[0006]

EXAMPLES The present invention will be explained below by way of examples. Referring to FIG. 1, the code division multiple access system according to the present invention includes first to fourth communication stations 11 to 14, and each communication station 11 to 14 is referred to as a wireless communication path (hereinafter simply referred to as a communication path). 15. A unique PN code is assigned to each communication station. Note that since each communication station performs transmission using a common carrier frequency, the communication path 15 is indicated by the sum (Σ) of the transmitted signals. Further, although the first to fourth communication stations are shown here, the number of communication stations may be three, or five or more.

[0007] Referring also to FIG. 2, each communication station 11 to 14 is equipped with a transmitter shown in FIG. The PN code generator 20 generates a plurality of PN codes, and selectively generates a partner station PN code (a PN code corresponding to the partner station to be transmitted) and a collective calling PN code in response to a PN code switching signal. The PN code is applied to a band spreading circuit 21, where the transmission data is spectrum spread (the transmission rate of the PN code is faster than the transmission rate of the transmission data), and is input to the modulator 22 as a spread data signal. The modulator 22 modulates the transmission carrier wave with the spread data signal and outputs it as a first modulated signal. Thereafter, the first modulated signal is band-limited by a band pass filter (BPF) 23, amplified by an intermediate frequency amplifier (IFAMP) 24, and given to a frequency converter 25 as an amplified signal. The frequency converter 25 performs frequency conversion of the transmission carrier wave using the local oscillation frequency given from the local oscillator 26, and supplies it to the power amplifier (power AMP) 27 as a second modulation signal. The power amplifier 27 amplifies the power of the second modulated signal and sends it out from the transmission antenna 28 as a transmission signal (frequency spread signal).

Next, referring to FIG. 3, each communication station 11 to 14 is equipped with a receiving section shown in FIG. The transmitted signal is received by the receiving antenna 30 as a received signal. This received signal is amplified by a high frequency amplifier (high frequency AMP) 31, and converted into an intermediate frequency signal by a frequency converter 32 using a local oscillation frequency given from a local oscillator 51. This intermediate frequency signal is band-limited by the BPF 33 and given to intermediate frequency amplifiers (IFAMP) 34 and 35, where it becomes an intermediate frequency amplified signal (here, the intermediate frequency amplified signal output from the intermediate frequency amplifier 34 is The intermediate frequency amplified signal output from the intermediate frequency amplifier 35 will be referred to as the second amplified signal).

The first amplified signal is applied to first and second correlators 36 and 37, respectively. The first correlator 36 detects a correlation peak and outputs it as a correlation peak value when the first amplified signal is a signal whose spectrum has been spread by the local station PN code. In this case, the second correlator 37
The noise level in the amplified signal is detected and output as a noise level value. On the other hand, when the first amplified signal is a signal whose spectrum has been spread by a PN code for collective calling, the second correlator 37 detects a correlation peak and outputs it as a correlation peak value. In this case, the first correlator 36
detects the noise level in the amplified signal of ).

First and second envelope detectors 38 and 39
Then, the first and second comparators 40 perform envelope detection of the first and second correlation signals and obtain first and second detected values.
and 41. First and second comparators 40 and 41
Then, the first and second detection values are compared with respective predetermined threshold values (Th), and first and second determination signals are sent out. For example, in the first and second comparators 40 and 41, when the first and second detection values exceed the threshold (Th), the first and second high level signals are used as the first and second judgment signals. Send out. The logical adder 42 logically adds the first and second determination signals to generate a logical addition signal. This logical addition signal is then used as a reset signal as described later.

The second amplified signal is applied to a synchronization tracking circuit 43 and a despreading circuit 44. The synchronization tracking circuit 43 is the local station P.
N code generator 43a and PN code generator 43 for batch calling
b, and when receiving the above logical addition signal, the local station PN code generator 43a and the batch calling PN code generator 4
3b is reset. Here, if the first and second amplified signals are signals whose spectra have been spread by the local station PN code, the synchronization tracking circuit 43 uses the local station PN code generator 43
Local station PN code from a (hereinafter referred to as oscillating local station PN code)
is tracked in synchronization with the local station PN code included in the second amplified signal.

It is now assumed that terminal a and terminal b of switch 45 are connected. PN code switching circuit 4
6 generates a switching signal upon receiving the second determination signal,
Here, the second determination signal is a second signal indicating the noise level value.
The PN code switching circuit 46 does not generate a switching signal because it is generated based on the correlation signal of , that is, it is not generated based on the correlation peak value. When the switch 47 does not receive the switching signal, the own station PN code generator 43
a and the despreading circuit 44 are connected. In other words, the oscillating local station P
The N code is given to the despreading circuit 44 as a reference PN code. The despreading circuit 44 despreads the second amplified signal based on the oscillating local PN code to generate a despread signal (this despread signal is equivalent to a signal (modulation signal) in which a carrier wave is modulated by transmission data). ). This despread signal is BPF4
8, the signal is band-limited and provided to the data demodulator 49. A data demodulator 49 demodulates the despread signal to obtain demodulated data.

On the other hand, when the reception section receives the transmission signal whose spectrum has been spread by the collective calling PN code as a reception signal, as is clear from the above description, the first correlation signal represents the noise level value, and the second correlation signal represents the noise level value. The correlation signal of will represent the correlation peak value. As a result, the PN code switching circuit 46
Then, a switching signal will be generated and sent. On the other hand, the logical adder 42 sends out a reset signal, thereby resetting the local PN code generator 43a and the batch calling PN code generator 43b. Then, in the synchronization tracking circuit 43, a P for batch call is generated from a PN code generator 43b for batch call.
The N code (hereinafter referred to as the oscillation batch call PN code) is synchronously tracked with the batch call PN code included in the second amplified signal.

The switch 47 connects the collective paging PN code generator 43b and the despreading circuit 44 using a switching signal. That is, the batch calling PN code is given to the despreading circuit 44. The despreading circuit 44 despreads the second amplified signal based on the oscillation batch calling PN code to generate a despread signal. This despread signal is band-limited by the BPF 48 and given to the data demodulator 49. A data demodulator 49 demodulates the despread signal to obtain demodulated data.

By the way, in the switch 45, the terminal a
and terminal c are connected, the switch 47 is controlled by the local station PN code selection signal and the collective calling PN code selection signal applied via the switch 50 to select the local station PN code and the terminal c, respectively. PN for batch calling
The code will be provided to despreading circuit 44. That is, when the terminals a and b are connected in the switch 50, the batch call PN code selection signal is given to the switch 47, which causes the switch 47 to select the batch call PN code generator 43b and the despreading circuit 44. Connect. On the other hand, when terminal a and terminal c are connected in switch 50,
The local station PN code selection signal is applied to the switch 47, whereby the switch 47 connects the local station PN code generator 43b and the despreading circuit 44. In this way, the local station PN code and the collective paging PN code can be selected as necessary.

[0016]

As explained above, in the present invention, a unique PN code and a common PN code are provided, and the received reference PN code is determined depending on whether the spread spectrum received signal is spread with the unique PN code or the common PN code. Since a unique PN code or a common PN code is sent out as a reference PN code, and the spread spectrum reception signal is demodulated based on this reception reference PN code, it is possible to support both individual paging and collective paging, and the circuit size is small. It has the effect of not becoming large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a code division multiple access system to which the present invention is applied.

FIG. 2 is a block diagram showing an embodiment of a transmitting section of a spread spectrum communication device according to the present invention.

FIG. 3 is a block diagram showing an embodiment of a receiving section of a spread spectrum communication device according to the present invention.

[Explanation of symbols]

11 to 14 Communication station 15 Communication channel 20 PN code generator 21 Spread band circuit 22 Modulator 23 Bandpass filter (BPF) 24 Intermediate frequency amplifier (IFAMP) 25 Frequency converter 26 Local oscillator 27 Power amplifier 28 Transmission antenna 30 Receiving antenna 31 High frequency amplifier 32 Frequency converter 33 Bandpass filter 34, 35 Intermediate frequency amplifier 36, 37 Correlator 38, 39 Envelope detector 40, 41 Comparator 42 Logic adder 43 Synchronous tracking circuit 44 Despreading circuit 45 Switch 46 PN Code switching circuit 47 Switch 48 Bandpass filter 49 Data demodulator 50 Switch 43a Own station PN code generator 43b Bulk call PN code generator 51 Local oscillator

Claims (3)

[Claims] Claim 1: A system comprising a plurality of stations, each of which is assigned a unique PN code, used in a code division multiple access system that performs code division multiple access between the stations, and transmits a spread spectrum transmission signal. In the spread spectrum communication device, a common PN code is assigned to all of the stations, and any one of the unique PN codes and the common PN code are selectively outputted as a transmission reference PN code. 1. A spread spectrum communication device comprising: a first selection means for performing spectrum spreading using the transmission reference PN code; and a transmission means for performing spectrum spreading using the transmission reference PN code and transmitting the spread spectrum transmission signal. 2. A system comprising a plurality of stations, each of which is assigned a unique PN code, used in a code division multiple access system that performs code division multiple access between the stations, and receives a spread spectrum received signal. In the spread spectrum communication device, all of the stations are assigned a common common PN code, receive the spread spectrum transmission signal according to claim 1 as a spread spectrum reception signal, and the spread spectrum reception signal is determining means for determining whether the spectrum has been spread by either the PN code or the common PN code and transmitting a determination signal, and selectively outputting the unique PN code or the common PN code according to the determination signal. a second selection means for determining the reception reference PN code; and
A spread spectrum communication device comprising demodulation means for demodulating the spread spectrum received signal based on a code. 3. A system comprising a plurality of stations, each of which is assigned a unique PN code, used in a code division multiple access system that performs code division multiple access between the stations, and transmits a spread spectrum transmission signal. In a spread spectrum communication device that receives a spread spectrum reception signal with a station, a common common PN code is assigned to all of the stations,
any one of the unique PN codes and the common P
The first one that selectively outputs the N code and uses it as a transmission reference PN code.
a selection means for performing spectrum spreading using the transmission reference PN code and transmitting the spread spectrum transmission signal; and upon receiving the spread spectrum reception signal,
determining means for determining whether the spread spectrum received signal has been spread spectrum by either the unique PN code or the common PN code and transmitting a determination signal; Spread spectrum communication characterized by having a second selection means for selectively outputting a code to use as a reception reference PN code, and a demodulation means for demodulating the spread spectrum received signal based on the reception reference PN code. Device.