JPH1141205A - Information signal transmitting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an information signal transmitting method which can achieve acceleration in the synchronism capture of spreading codes at respective slave stations, which has been an issue in a conventional CDMA system. SOLUTION: In this method, when transmitting 1st - Nth information signals (N is an integer >=2) form a master station to 1st-Nth slave stations, 1st-Nth spreading codes c1 having the mutually same code length and code constitution are respectively generated in the state of successively shifting the rising timing of the 1st - 4th spreading codes c1 [corresponding to (1) to (4) on the lateral axis] just for prescribed time corresponding to the 1/N code length, and the 1st - Nth information signals are respectively spectrum-spread by the 1st - Nth spreading codes into 1st - Nth spectrum-spread signals. Then, the 1st - Nth spectrum-spread signals are respectively transmitted to the 1st - Nth slave stations while using 1st - Nth carrier waves having the mutually same frequency f1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information signal transmission method for transmitting a plurality of information signals from one master station to a plurality of slave stations using a plurality of transmission paths.

[0002]

2. Description of the Related Art Here, a master station and a slave station are, for example, a master apparatus and a terminal, a base station and a mobile station, wherein the master station manages the timing and channel assignment of the entire network, and Depends on what is synchronized.

Conventionally, one master station transmits first to Nth information signals to first to Nth (N is an integer of 2 or more) slave stations using first to Nth carrier waves. As an information signal transmission method, FDMA (Frequency Di) is used.
Vision Multiple Access (TDMA) system, Time Division Multi (TDMA)
ip access system, CDMA (code)
Division Multiple Access)
There is a method.

[0004]

FIG. 2 shows signals when four channels are multiplexed using the FDMA system. In FIG. 2, to represent first to fourth transmission paths (communication channels) for performing communication with the first to fourth slave stations, respectively. As shown in FIG. 2, in the FDMA method, first to fourth signals having different center frequencies f1 to f4, respectively, are used.
To the first to fourth transmission paths,
Is configured. Since the first to fourth carriers are different, the transmission of the information signal to a certain slave station can be performed independently of the transmission of the information signal to another slave station. Since the frequencies f1 to f4 are different, the frequency f
There is a disadvantage that a synthesizer for selecting 1 to f4 needs to be provided.

FIG. 3 shows signals when multiplexing four channels using the TDMA method. In FIG. 3 as well, as in FIG. 2, 〜 indicates first to fourth transmission paths (communication channels) for performing communication with the first to fourth slave stations, respectively. The horizontal axis represents the start point of the time slot allocated to the first to fourth transmission paths. As shown in FIG. 3, in the TDMA system, carriers having the same frequency f1 are used as the first to fourth carriers for the first to fourth slave stations, and a plurality of time-divided time slots are assigned to the first to fourth carriers. Used as the first to fourth transmission paths. The time slots of the first to fourth transmission paths are shifted in time by the length of the time slot. The transmission of the information signal to each of the first to fourth slave stations can use only the time (time slot) allocated to the slave station, and the transmission of the information signal to each slave station can be performed continuously in time. There is a drawback that you can not.

FIG. 4 shows signals when multiplexing four channels using the CDMA system. In FIG. 4 as well, as in FIG. 2, represent the first to fourth transmission paths (communication channels) for performing communication with the first to fourth slave stations, respectively. As shown in FIG. 4, in the CDMA system, carriers having the same frequency f1 are used as first to fourth carriers for the first to fourth slave stations, and the first to fourth spreading codes c1 to c4 are used. The first to fourth transmission paths are configured by using spread codes (in the case of direct spreading) having different code configurations as c4 for spectrum spreading. Since the first to fourth transmission paths use different first to fourth spreading codes c1 to c4, transmission of an information signal to a certain slave station can be performed independently of transmission of an information signal to another slave station. it can. However, the first to fourth slave stations use the first to fourth spreading codes c1 to c4 to perform the first to fourth spreading codes.
The first to fourth spread codes c1 to c4 are provided to despread the first to fourth spread-spectrum signals generated by performing spread spectrum on the information signals, respectively. The fourth to fourth spread spectrum signals and the first to fourth spread codes c1
By finding the point where the correlation with ~ c4 becomes large,
The synchronization of the spreading code is performed.
To the acquisition of the spreading code in each of the fourth to fourth slave stations,
A time corresponding to the length of the spreading code is required at the maximum, and speeding up synchronization acquisition is an issue. Like this, CD
The MA method has a drawback that the first to fourth slave stations cannot perform processing at high speed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and eliminate the need to equip each slave station with a synthesizer for selecting a frequency, and to continuously transmit information signals to each slave station. It is an object of the present invention to provide an information signal transmission method which can perform the processing at high speed by each of the slave stations.

[0008] Another object of the present invention is to provide a conventional CDM.
It is an object of the present invention to provide an information signal transmission method capable of achieving high-speed synchronization acquisition in each of the slave stations, which has been a problem in the A system.

[0009]

According to the present invention, the first to N-th information signals are transmitted from one master station to the first to N-th (N is an integer of 2 or more) slave stations. In the method of transmitting using the first to N-th carrier waves having the same frequency, the master station may use the first to N-th spreading codes having the same code length and code configuration as the first to N-th spreading codes. The rising timing of the Nth spreading code is 1/1 of the code length.
A spreading code generating step that is generated in a state where the spreading codes are sequentially shifted by a predetermined time corresponding to N, and in the master station, the first to N-th information signals are converted by the first to N-th spreading codes. Each spread spectrum, the first
And a spread spectrum step for outputting the N th spread spectrum signals, respectively,
Transmitting the first to the N-th spread spectrum signals to the first to the N-th slave stations using the first to the N-th carrier waves, respectively. A signal transmission method is obtained.

Preferably, the first to the N-th information signals are transmitted to the first to the N-th slave stations so as to determine that the first to the N-th information signals are information signals addressed to themselves. Each contains the identification code of the slave station.

Alternatively, the information signal located at the head of the first to Nth information signals may selectively extract the information signal addressed to itself to the first to Nth slave stations. It may include a reference code indicating a time reference at the time of execution.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

An information signal transmission method according to an embodiment of the present invention will be described with reference to FIG.

In this information signal transmission method, the first to N-th information signals are transmitted from one master station to first to N-th (N is an integer of 2 or more) slave stations. This is a method of transmitting data via a channel. FIG. 1 shows a case where N is 4. In FIG. 1 as well as in FIG. 2, the symbols 乃至 to 行 う are used to communicate with the first to fourth slave stations, respectively.
Represents a transmission path (communication channel). As shown in FIG. 1, in this information signal transmission method, the same frequency f is used as the first to fourth carrier waves for the first to fourth slave stations.
1 using a carrier having the same code length and code configuration as the first to fourth spreading codes for the first to fourth slave stations for spectrum spreading, as shown below. And the first to fourth transmission paths
Is configured.

That is, in the main station, the first to fourth spreading codes c1 having the same code length and code configuration are set to 1/4 the rising timing of the first to fourth spreading codes c1. 4 (generally 1 / N) in a state shifted sequentially by a predetermined time. Subsequently, the main station spreads the first to fourth information signals with the first to fourth spreading codes, respectively, and outputs the first to fourth spectrum-spread signals, respectively. Then, in the master station, the first to fourth spread-spectrum spread signals are transmitted to the first station having the same frequency f1.
To the fourth to fourth transmission paths using the fourth carrier to
, To the first to fourth slave stations respectively. FIG.
, The horizontal axis represents the starting point (rising timing) of the first to fourth spreading codes c1 in the first to fourth spread spectrum signals transmitted to the first to fourth transmission paths. I have.

As described above, in the present invention, multiplex communication is performed by using the same spread spectrum code shifted in time. Therefore, the method according to the present invention uses SCMA (Slid).
This is referred to as an eCode Multiple Access (eCode Multiple Access) method.

FIG. 1 shows signals when four channels are multiplexed using the SCMA method.
The first to fourth spreading codes c1 of the transmission lines 1 to 4 use a common code, but the main station starts generating the first to fourth spreading codes c1 of the first to fourth transmission lines 1 to 4. Are temporally shifted by one-seventh the number of channels of the length of the spreading code c1 as shown in the figure. The slave station synchronously captures the starting point of the spread code c1 from the master station.
However, since the first to fourth spreading codes c1 are shifted in time, transmission of an information signal to a certain slave station can be performed continuously irrespective of transmission of an information signal to another slave station.

As described above, the SCMA system uses the same spreading code, shifts the starting points of the spreading code at equal intervals, and is temporally continuous if only one communication is viewed. According to this, there are the following advantages.

In the SCMA system, a frequency synthesizer required in the conventional FDMA system becomes unnecessary. Because the multiplexing by the spreading code is performed, the carrier is 1
This is because information signals can be multiplexed by waves.

In the SCMA system, it is possible to capture synchronization of a spread code faster than in the conventional CDMA system.

In the conventional CDMA system, as described above, the first to fourth slave stations perform the first to fourth spreading codes c.
First to fourth spread codes c1 to despread the first to fourth spread-spectrum signals generated by spectrum spreading the first to fourth information signals at 1 to c4, respectively. To c4, respectively, and finds a point where the correlation between the first to fourth spread spectrum signals and the first to fourth spread codes c1 to c4 becomes large, thereby acquiring synchronization of the spread codes. . At this time, in each slave station, as shown in FIG. 5, the synchronization acquisition of the spread code of the spectrum-spread signal received as the received signal is performed by shifting the spread code provided in the slave station with respect to the received signal. Is performed by finding a point where is larger than “0”.

Therefore, it takes a time corresponding to the length of the spread code at the maximum for the synchronization capture of the spread code in each slave station, and it is not possible to perform the synchronization capture at high speed. For this reason,
In the conventional CDMA system, each slave station cannot perform processing at high speed.

FIG. 5 shows a case where the slave station receives a signal generated by spectrum-spreading the information signal with the same spreading code as that provided therein. When the slave station receives a signal generated by spectrum-spreading an information signal with a spreading code different from the spreading code provided therein, as shown in FIG. Does not grow.

On the other hand, for example, when N = 3 (that is, when the same spreading code is used for spread spectrum at three times while shifting the time), each slave station in the SCMA system synchronously captures the spreading code. , As shown in FIG. In this case, each slave station is provided with the same spreading code as the spreading code used for spectrum spreading at the master station, for spectrum despreading of the spectrum spread signal, and the spectrum spread signal received as a received signal is provided. By finding a point where the correlation between the signal and the spreading code becomes large, the synchronization of the spreading code is acquired. At this time, each slave station acquires the spread code of the spread spectrum signal received as a received signal synchronously by shifting the spread code provided in the slave station with respect to the received signal as in the case of FIG. This is performed by finding a point where the value becomes larger than "0". However, in the SCMA method, the same spread code is used at a different time for transmission of a spread spectrum signal. Therefore, as shown in FIG. If the synchronization is obtained at the start timing of the spread code, the content of the information signal in the spread spectrum signal can be read.

As a result, in the example of FIG.
The time required to find a point larger than 0 "" is a maximum of 1/3 of the spreading code length (generally, 1 / N).
Only needs to be done.

Here, the slave station moves to its own use timing by a method different from synchronization of the spreading code (finding a point where the correlation value becomes larger than "0" while shifting the spreading code). Can be used.

For example, as a first method, in the master station, the first to N-th information stations to be transmitted to the first to N-th slave stations and the information signal addressed to itself to the first to N-th slave stations are transmitted. It is conceivable to include the identification codes of the first to Nth slave stations in order to determine that In this case, the first to N-th slave stations determine that an information signal including their own identification code is an information signal addressed to themselves, and extract only the information signal.

As a second method, the main station performs the first method.
The information signal destined for itself to the first to Nth slave stations is selectively extracted from the information signal (for example, the first information signal) positioned temporally at the top of the Nth to Nth information signals. A reference code indicating a time reference at that time may be included. In this case, the first to N-th slave stations have a rule in advance that the information signal is an information signal addressed to itself after detecting the reference code. Is
When the reference code is detected, an information signal addressed to itself is selectively extracted according to the above-mentioned rules.

In the conventional TDMA system, the transmission of the information signal to each slave station could not be continuously performed in time, but in the SCMA system, the transmission of the information signal to each slave station was continuously performed in time. be able to.

This is because, in the SCMA system, information signals can be transmitted continuously instead of in a time-sharing manner, and there is no time during which information cannot be transmitted unlike the TDMA system.

Next, an example in which the present invention is applied to a digital cellular telephone will be described.

Here, originally, TDMA / FDD (Ti
me Division Multiple Access
ss / Frequency Division Dup
LEX), a digital cellular telephone system using SCMA / CDD (Slid) in accordance with the present invention.
e Code Multiple Access / Co
An example realized by a de Division Duplex method will be described.

FIG. 8 shows a conventional RCR (Research).
& Development Center for
Radio System: Radio System Development Center)
1 illustrates a wireless channel configuration of a digital cellular telephone system based on STD-27.

In the RCR STD-27, three channels are multiplexed in one TDMA system per carrier. Furthermore, in order to realize two-way simultaneous communication as a telephone, an FDD system using different carrier waves (f1 and f2) for the base station (master station) → mobile station (slave station) and mobile station → base station is adopted. ing. In FIG. 8, FIG.
Similarly, と indicates first to third transmission paths (communication channels) for performing communication between the base station and the first to third mobile stations, respectively. The horizontal axis represents the first to third transmission paths to
Represents the start point of the time slot assigned to.

The information transmission rate is 42 kbps (21 k symbols / sec when using π / 4 shift QPSK). However, the time per time slot is 20 /
In 3 msec, the net information transmission amount excluding the guard time is 270 b per channel in the case of a communication channel.
it / 20 msec (= 13.5 kbps), in the case of a control channel, 258 bits / 20 m per channel
sec (= 12.9 kbps).

FIG. 9 shows a radio channel configuration of a digital cellular telephone system using the SCMA / CDD system according to the present invention. To be the same as RCR STD-27, three channels per spreading code (ie, N
= 3) are multiplexed. Base station → mobile station and mobile station →
C using different spreading codes c1 and c2 for the base station
The DD system is adopted. However, the same carrier (f1) is used for the base station → mobile station and the mobile station → base station. In FIG. 9 as well, as in FIG. 8, 〜 indicates first to third transmission paths (communication channels) for performing communication between the base station and the first to third mobile stations, respectively. The horizontal axis is
The starting point of the time slot allocated to the first to third transmission paths (in this case, the first to third transmission paths to
(The starting point of the spread codes c1 and c2 in the spread spectrum signal transmitted to the base station). The time per time slot is 20 msec,
Since no time is required, the net information transmission rate is equal to the physical information transmission rate, and in the case of a communication channel, 1
3.5 kbPS, 12.9 kbp for control channel
s.

FIG. 10 shows the SCMA / CDD according to the present invention.
1 shows a configuration example of a digital cellular radio provided in a mobile station (slave station) of a digital cellular telephone system in a case where the system is used. This mobile station, like other mobile stations,
From the base station, the first to third spread-spectrum signals generated by spread-spectrum the first to third information signals at the same time with the same spreading code c1 are transmitted to the same frequency f1. The radio wave transmitted using the first to third carrier waves is received. The receiving route is
A radio wave input from the antenna 1 is separated by the duplexer 2 and amplified by the low noise amplifier 3. The amplified radio wave is received by the spreading code c1 generated by the spreading code generator 11.
The output signal of the modulated wave generator 12 modulated by the above is mixed with the mixer 4 to obtain an intermediate frequency (IF) signal.
This intermediate frequency signal is amplified again by the intermediate frequency (IF) amplifier 6 and then input to the SCMA modulator / demodulator 10. As described with reference to FIG. 7, the SCMA modulator / demodulator 10 performs synchronization acquisition of the spread code c1 by finding a point having a large correlation value, and performs this shift from the first to third information signals. The extraction of the information signal addressed to the station is performed according to the above-described first or second method.

The transmission path is such that the information signal assembled by the SCMA modulator / demodulator 10 is a modulated wave generator 1 modulated by a transmission spreading code c 2 generated by a spreading code generator 11.
2 is mixed with the carrier at the mixer 8 and the radio frequency (R
F) signal. The radio frequency signal is amplified by the transmission power amplifier 9, mixed by the duplexer 2, and radiated from the antenna 1 into the air.

The SCMA / according to the present invention shown in FIG.
In the radio channel configuration of the digital cellular telephone system using the CDD method, three channels (that is, when N = 3) are multiplexed per one spreading code in order to make it the same as RCR STD-27. To multiplex many channels with one spreading code, the radio channel is configured as follows.

For example, from the time of one bit of the spreading code,
When the delay time of the entire network is large, FIG.
As shown in (1), the code length is divided into equal intervals as finely as possible within a range larger than the delay time of the entire network, and the divided interval is set as the time interval of the starting point of the spreading code. Note that in FIG. 11 as well as in FIG. 1, represent the first to ninth transmission paths (communication channels) for performing communication with the first to ninth mobile stations (slave stations), respectively. The axis is the first to ninth
The first to ninth spread codes c1 in the first to ninth spread spectrum signals transmitted to the transmission path
(Rising timing).

When the delay time of the entire network is shorter than the 1-bit time of the spreading code, as shown in FIG. 12, the 1-bit time of the spreading code is the minimum time interval between the starting points of the spreading code. . In FIG. 12, similarly to FIG. 1, the circle numbers 20 represent the first through twentieth transmission paths (communication channels) for communicating with the first through twentieth mobile stations (slave stations), respectively. The horizontal axis represents the starting point (rising timing) of the first to twentieth spread codes c1 in the first to twentieth spread spectrum signals transmitted to the first to twentieth transmission paths to the circled numeral 20. Is represented.

[0042]

As described above, according to the present invention, it is not necessary to equip each slave station with a synthesizer for selecting a frequency, and it is possible to continuously transmit information signals to each slave station. An information signal transmission method that allows each of the slave stations to perform processing at high speed is obtained.

Further, according to the present invention, there is provided an information signal transmission method capable of achieving high-speed synchronization acquisition in each of the slave stations, which has been a problem in the conventional CDMA system.

[Brief description of the drawings]

FIG. 1 is an information signal transmission method (S) according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining a CMA method.

FIG. 2 is a diagram for explaining a method of multiplexing four channels using a conventional FDMA method.

FIG. 3 is a diagram for explaining a method of multiplexing four channels using a conventional TDMA method.

FIG. 4 is a diagram for explaining a method of multiplexing four channels using a conventional CDMA method.

FIG. 5 is a diagram for explaining synchronization acquisition of a spreading code in a conventional CDMA system.

FIG. 6 is a diagram for explaining synchronization acquisition of a spreading code in a conventional CDMA system.

FIG. 7 is a diagram for explaining synchronization acquisition of a spread code in the SCMA system of the present invention.

FIG. 8 is a diagram showing a radio channel configuration of a conventional cellular cellular telephone system based on RCR STD-27.

FIG. 9 is a diagram showing a radio channel configuration of a digital cellular telephone system using the SCMA / CDD system according to the present invention.

FIG. 10 is a block diagram showing a configuration of a digital cellular radio provided in a mobile station (slave station) of a digital cellular telephone system when the SCMA / CDD system according to the present invention is used.

FIG. 11 is a diagram for explaining the configuration of a wireless channel for multiplexing many channels with one spreading code (when the delay time of the entire network is longer than the 1-bit time of the spreading code) in the present invention. .

FIG. 12 is a diagram for explaining the configuration of a wireless channel for multiplexing many channels with one spreading code (when the delay time of the entire network is smaller than the 1-bit time of the spreading code) in the present invention. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna 2 Duplexer 3 Low noise amplifier 4 Mixer 6 Intermediate frequency amplifier 8 Mixer 9 Transmission power hatcher 10 SCMA modulator / demodulator 11 Spread code generator 12 Modulated wave generator

Claims (3)

[Claims] A first master transmits first to N-th information signals to first to N-th (N is an integer of 2 or more) slaves from one master station.
In the method of transmitting using the first to N-th carrier waves having the same frequency, the master station transmits the first to N-th spreading codes having the same code length and code configuration to each other. 1 to the N-th
A spreading code generating step in which rising timings of the spreading codes are sequentially shifted by a predetermined time corresponding to 1 / N of the code length, wherein the main station has the first to Nth information A spectrum spreading step of spreading the signal with the first to the N-th spreading codes and outputting the first to N-th spread signals, respectively; Transmitting the spread spectrum signal to the first to Nth slave stations using the first to Nth carrier waves, respectively. 2. The first to Nth slave stations for causing the first to Nth slave stations to determine that they are information signals addressed to themselves. The information signal transmission method according to claim 1, wherein each of the information signals includes an identification code. 3. An information signal located at the head of time among the first to Nth information signals selectively extracts an information signal addressed to itself to the first to Nth slave stations. 2. The information signal transmission method according to claim 1, further comprising a reference code representing a time reference at the time.