JPH09261118A - Spread spectrum communication equipment - Google Patents

Abstract

(57) Abstract: To provide a spread spectrum communication device capable of efficiently making multiple access to mobile stations by selecting an information rate for each mobile station. SOLUTION: An encoder 11 that selects one from a plurality of error correction coding rates and coding systems and performs error correction coding on information, and information that has been coded for these error corrections are provided. A decoder 6 for decoding, a transmission power control circuit 15 and an RF transmitter 14 for changing and transmitting transmission power, and one of a plurality of information rates is selected and an error correction coding rate is selected according to the information rate. And an encoding method, a decoding method, and a control circuit 16 that switches the transmission power of the information data portion, a decoding method selection circuit 17, and an encoding method selection circuit 18, and select an information rate from a plurality of information rates. It is possible to efficiently connect multiple mobile stations according to the selected information speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spread spectrum communication device using a spread spectrum system used for digital radio communication such as a car phone and a mobile phone.

[0002]

2. Description of the Related Art In a cellular radio system such as an automobile telephone and a mobile telephone, FDM is used as a transmission data processing method in which a plurality of stations simultaneously communicate in the same frequency band.
A method and TDMA method are known, but in recent years, F method
As compared with the techniques such as the DMA system and the TDMA system, higher frequencies can be used, and the CDMA system (code division multiple access system) has come to be adopted as a system capable of accommodating more users.

Further, as a transmission method for transmitting transmission data bidirectionally between a mobile station and a base station of a cellular system, there are an FDD method and a TDD method. The FDD system is a system that uses different frequency bands for the uplink and the downlink, and the TDD system is a system that uses the same frequency band and transmits the uplink and the downlink in a time division manner. Therefore, the CDMA / TDD system is a system that processes a signal transmitted by the CDMA system, and performs transmission on the uplink and the downlink by a time division multiplexing system (TDD).

A conventional CDMA / TDD system spread spectrum communication device is shown in FIG. FIG. 7 is a block diagram showing a configuration of a mobile station of a conventional CDMA / TDD system spread spectrum communication device. The configuration of a conventional CDMA / TDD system spread spectrum communication apparatus will be described below with reference to FIG.

In FIG. 7, 39 is an antenna for receiving transmitted radio waves, 40 is a switch for switching between transmission and reception, and 41
Converts the received RF signal into a baseband signal R
F receiver, 42 is an AD for quantizing the baseband signal
A converter, 43 is a correlator that despreads the AD-converted data and outputs correlation value data, 44 is a decoder that decodes the correlation value data and outputs decoded data 47, and 45 is the correlator 4
3 is a synchronization circuit that outputs a synchronization signal to 3 to generate a frame synchronization signal and outputs the frame synchronization signal to the timing generation circuit 46. Reference numeral 46 is a timing generation circuit that controls switching in the switch 40.

Reference numeral 49 denotes an encoder for assembling the frame structure of transmission data and control data to perform error correction coding on the transmission data 48, and 50 denotes spectrum spreading of the coded data to multiplex each channel. A spread-multiplexing circuit for converting the spread-spectrum-multiplexed digital data into an analog signal, a DA converter 52 for converting the spread-spectrum-multiplexed analog signal into an RF signal, and a transmission power control circuit 54. A control circuit that sends a control signal to the encoder 49 to control the transmission power and outputs control data to be transmitted to the encoder 49.
Is a transmission power control circuit for controlling the transmission power of the RF signal.

Next, referring to FIG. 7, a conventional CDMA /
The operation of the TDD spread spectrum communication apparatus will be described. On the receiving side of FIG. 7, the antenna 39 receives the radio wave transmitted from the device at the other end of communication. The switch 40 switches the transmission / reception to reception and outputs the received RF signal to the RF reception unit 41. The RF receiver 41 converts or detects the received RF signal into a baseband signal and outputs the baseband signal to the AD converter 42. The AD converter 42 quantizes the baseband signal and outputs it to the correlator 43 and the synchronizing circuit 45. The correlator 43 despreads the AD-converted data with the synchronization signal from the synchronization circuit 45 and outputs the correlation value data to the decoder 44, and the decoder 44 decodes the correlation value data output from the correlator 43. And outputs the decoded data 47.

Therefore, the decoded data 47 is also output to the control circuit 53 and the synchronizing circuit 45. Further, the synchronization circuit 45 performs chip synchronization and symbol synchronization from the output of the AD converter 42 and outputs a synchronization signal to the correlator 43, generates a frame synchronization signal from the decoded data 47 and outputs it to the timing generation circuit 46. . The timing generation circuit 46 controls switching of transmission and reception in the switch 40 by controlling the frame synchronization signal.

On the transmission side of FIG. 7, the encoder 49 assembles the frame structure of the transmission data and the control data based on the control signal from the control circuit 53 and performs error correction coding on the transmission data 48 to perform spread multiplexing. Circuit 50
Output to The spread-and-multiplex circuit 50 multiplexes each channel for spectrum-spreading and transmitting the encoded data,
Output to the DA converter 51. The DA converter 51 converts the spread spectrum multiplexed digital data into an analog signal and outputs the analog signal to the RF transmission unit 52, and the RF transmission unit 52 converts or modulates the spread spectrum multiplexed analog signal into an RF signal.

Therefore, the switch 40 switches the transmission / reception to the transmission and outputs the RF signal to be transmitted from the antenna 39. Further, the control circuit 53 extracts control data from the decoded data, sends a control signal to the transmission power control circuit 54 to control the transmission power, and outputs the control data to be transmitted to the encoder 49 to transmit the transmission power. The control circuit 54 controls the transmission power of the RF transmission unit according to the control signal from the control circuit 53.

The above-mentioned conventional CDMA / TDD system spread spectrum communication device has an information rate of 1 for transmission data to be transmitted.
Since the type is fixed, the transmission is performed at a fixed information rate even if the amount of traffic or the amount of information such as the voice of the user to be transmitted changes.

[0012]

However, since the above-described conventional spread spectrum communication device has a fixed information rate and cannot select and transmit the information rate, the amount of traffic and the presence / absence of the voice of the user who transmits the information can be determined. There has been a problem that a large number of users cannot be accommodated efficiently with respect to changes in the amount of information.

The present invention has been made in order to solve the above-mentioned conventional problems, and the information rate can be selected for each mobile station that makes multiple access (multiple access connection). While maintaining a certain communication quality, the number of users can be increased or decreased in response to changes in the amount of traffic or the amount of information transmitted by the user, such as the presence or absence of voice, so that multiple mobile stations can efficiently make multiple connections. An object of the present invention is to provide a spread spectrum communication device.

[0014]

A spread spectrum communication apparatus according to the present invention selects one of a plurality of coding methods having a coding rate for error correction and performs error correction coding on transmission information. A means for performing, a means for decoding coded information for error correction, a means for changing transmission power and transmitting, and a code for error correction depending on the information rate by selecting one from a plurality of information rates. A code for error correction, which is configured by including means for switching between an encoding method and a decoding method having a conversion rate and a means for switching the transmission power of the information data portion, so that the information rate can be selected for each mobile station to which multiple access is made. The coding method having a coding rate is switched, and the transmission power is switched so that a constant communication quality is obtained.

According to the present invention, the information rate can be selected for each mobile station that makes multiple access (multiple access connection),
The transmission power of each device is switched according to the change of the information speed to maintain the almost constant communication quality regardless of the change of the information speed, and the change of the information quantity such as the traffic volume and the presence or absence of the voice of the user who transmits. Since it is possible to increase or decrease the number of users in accordance with, it is possible to obtain a spread spectrum communication apparatus capable of efficiently making multiple access to a large number of mobile stations.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention converts a received RF signal into a baseband signal,
Quantization, despreading, means for decoding and outputting decoded data, and error correction coding for transmission data, assembling frame structure of transmission data and control data, spectrum spreading and multiplexing each channel, In a spread spectrum communication apparatus of a CDMA / TDD system having means for converting into an analog signal and transmitting it, one of a plurality of coding systems having a coding rate of error correction is selected and an error correction code is set as information. Means, a means for decoding the information coded for error correction, a means for changing the transmission power and transmitting the information, and one of a plurality of information speeds is selected according to the information speed. The present invention is provided with a means for switching an encoding method having an error correction encoding rate, a decoding method, and a transmission power of an information data portion, and information is provided for each mobile station to which multiple access is made. The transmission rate can be selected, the data rate can be transmitted with a substantially constant communication quality by switching the coding rate and the transmission power according to the change of the information rate, and the traffic amount and the information amount transmitted by the mobile station. This has the effect of enabling multiple access to multiple mobile stations efficiently in response to changes in

The invention according to claim 2 of the present invention is
Depending on the information rate, means for providing a portion that does not transmit transmission data in one frame, means for reducing the transmission power of that portion for transmission, and frame start timing for each of the multiple-connected devices It is provided with a means for communicating at different times, the information speed can be selected, data communication can be performed with a substantially constant communication quality, and more multiple devices can be efficiently connected in multiple ways. Has the effect of.

The invention according to claim 3 of the present invention is
A means for selecting an information rate from the information rates of 8 Kbps, 16 Kbps and 32 Kbps, and switching error correction coding rates of 1/4, 1/2 and no error correction corresponding to the selected information rate. Means for encoding,
It is provided with means for decoding the error-correction coded information and means for switching the transmission power of the information data portion corresponding to the information speed, and 8 Kbps, 16
One can be selected from the information rates of Kbps and 32 Kbps, data communication can be performed with a substantially constant communication quality, and a large number of devices can be used in response to changes in traffic volume and information volume from mobile stations. It has the effect of enabling multiple access efficiently.

The invention according to claim 4 of the present invention is
Information speed 8Kbps, 4Kbps, 2Kbps, 1Kb
A unit for selecting an information rate in ps, a unit for forming a portion having no information data in a frame with a data amount according to the selected information rate, and reducing transmission power of the portion, and each device for multiple access And a means for transmitting by shifting the frame start timing for each frame. Information speed 8 Kbps, 4 Kbps, 2 Kbps, 1 Kbp
Since the information speed can be selected from s, the number of users who can be connected simultaneously can be switched according to the selected information speed, data communication can be performed with an almost constant communication quality, and more information speed can be selected. It has an effect that multiple devices can be efficiently connected in multiple ways.

Hereinafter, based on the attached drawings and FIGS. 1 to 6,
An embodiment of the present invention will be described in detail. 1 is a block diagram showing a configuration of a mobile station of a CDMA / TDD system spread spectrum communication apparatus according to a first embodiment of the present invention, and FIG. 2 is a frame configuration for each information rate of the spread spectrum communication apparatus shown in FIG. FIG. 3 is a block diagram showing a schematic configuration of a base station that communicates with a mobile station of the spread spectrum communication apparatus according to the first exemplary embodiment of the present invention. FIG. 4 is a block diagram showing the second exemplary embodiment of the present invention. CDMA in the embodiment
FIG. 5 is a block diagram showing the configuration of a mobile station of the / TDD spread spectrum communication device, and FIG. 5 shows the configuration of one frame for each information rate and the transmission power of the spread spectrum communication device according to the second embodiment of the present invention. FIG. 6, FIG. 6 is the second shown in FIG.
FIG. 3 is a diagram showing transmission / reception timing for each mobile station in the embodiment of the present invention.

The configuration of the mobile station of the CDMA / TDD system spread spectrum communication apparatus according to the first embodiment of the present invention will be described below with reference to FIG. On the receiving side of FIG. 1, 2 is a switch for switching between transmission and reception, 3
Is an RF receiver that converts an RF signal into a baseband signal, and 4 is an AD converter that quantizes the baseband signal,
Reference numeral 5 denotes a correlator that despreads the AD-converted received data and outputs correlation value data.

Reference numeral 6 is a decoder for decoding the correlation value data from the correlator 5 and outputting the decoded data. Reference numeral 7 is a chip synchronization and symbol synchronization from the output of the AD converter 4 and a synchronization signal for the correlator 5. Is a timing generation circuit for generating a frame synchronization signal from the decoded data 9 and outputting the frame synchronization signal to the timing generation circuit 8. Reference numeral 8 is a timing generation circuit for switching the transmission and reception of the switch 2 by the frame synchronization signal from the synchronization circuit 7.

On the transmitting side of FIG. 1, 10 is an encoder 1.
The transmission data encoded by 1 and transmitted, 11 is the control circuit 16 that performs error correction encoding on the transmission data 10.
An encoder that assembles a frame structure of transmission data and control data by a control signal from 12; a spread multiplexing circuit that spreads the coded data to multiplex each channel; 13 is spread spectrum multiplexed. It is a DA converter that converts digital data into analog signals.

Further, 14 is an RF transmitter for converting an analog signal subjected to spread spectrum multiplexing into an RF signal, 15 is a transmission power control circuit for controlling the power of the RF transmission signal by a control signal from the control circuit 9, and 16 is an information rate. Corresponding to the control circuit for transmitting the control signal for selecting the decoding system and the control signal for selecting the encoding system, 17 is a decoding system selecting circuit for switching the decoding system of the decoder 6 according to the control signal of the control circuit 16,
Reference numeral 18 denotes a coding system selection circuit that switches the coding system for error correction in the encoder 11 according to the control signal of the control circuit 16.

In the present embodiment, the RF transmitter 14 and the transmission power control circuit 15 constitute means for changing and transmitting the transmission power, and the control circuit 16, the decoding system selection circuit 17, and the encoding system selection are performed. A circuit 18 selects one from a plurality of information rates, and switches the coding method and the decoding method having the coding rate of error correction and the transmission power of the information data portion according to the information rate, and the information rate of 8 Kb.
A means for selecting an information rate from ps, 16 Kbps, and 32 Kbps is configured.

Next, the operation of the mobile station of the CDMA / TDD system spread spectrum communication apparatus according to the first embodiment of the present invention will be described with reference to FIG. On the receiving side of FIG. 1, when the switch 2 is selected for reception,
The antenna 1 receives the radio wave transmitted from the device with which it communicates. The RF receiving unit 3 converts the RF signal into a baseband signal and outputs it to the AD converter 4. The AD converter 4 quantizes the baseband signal and outputs it to the correlator 5 and the synchronizing circuit 7. The correlator 5 despreads the AD-converted data according to the synchronization of the synchronization signal output from the synchronization circuit 7, and outputs the correlation value data to the decoder 6.

The decoder 6 decodes the correlation value data output from the correlator 5 and outputs decoded data 9. The decoder 6 is composed of a plurality of error correction decoding circuits of different systems. Here, it is assumed that the decoding circuit is composed of three types of decoding circuits with coding rates of 1/4 and 1/2 and without error correction.
Information speed 8Kbps, 16Kbps, 32Kb
Decrypt corresponding to ps. The decoding method selection circuit 17 selects the decoding method. The decoded data 9 is also output to the control circuit 16 and the synchronization circuit 7.

The synchronizing circuit 7 performs chip synchronization and symbol synchronization from the output of the AD converter 4 and outputs the synchronization signal to the correlator 5
And a frame synchronization signal is generated from the decoded data 9 of the decoder 6 and is output to the timing generation circuit 8. The timing generation circuit 8 switches the switch 2 according to the frame synchronization signal from the synchronization circuit 7, and the switch 2 switches between transmission and reception.

Next, on the transmission side of FIG.
Reference numeral 1 denotes an error correction coding of the transmission data 10 and, at the same time, assembles a frame structure of the transmission data and the control data by a control signal from the control circuit 16 to perform the spreading and multiplexing circuit 1.
Output to 2. The encoder 11 is composed of three types of coding devices with error correction coding rates of 1/4 and 1/2 and no error correction and an arithmetic device that assembles a frame structure. The selection is performed by the encoding system selection circuit 18.

The spread-and-multiplex circuit 12 spreads the encoded data by spectrum spreading and multiplexes each channel for transmission, and D
Output to the A converter 13. The DA converter 13 converts the spread spectrum multiplexed digital data into an analog signal and outputs the analog signal to the RF transmitter 14. The RF transmitter 14 converts or modulates the spread spectrum multiplexed analog signal into an RF signal. The RF signal is output from the antenna 1 when the switch 2 is selected for transmission. The transmission power control circuit 15 controls the power of the RF transmission signal based on the control signal from the control circuit 9.

The control circuit 16 sends a decoding system selection control signal to the decoding system selection circuit 17 in accordance with the information rate.
Further, it sends a control signal for selecting a coding system to the coding system selection circuit 18, and sends a control signal for transmission power to the transmission power control circuit 15 according to the information rate of the transmission signal. The decoding system selection circuit 17 switches the decoding system of the decoder 6 according to a control signal from the control circuit 16. The encoding system selection circuit 18 switches the encoding system for error correction in the encoder 11 according to the control signal from the control circuit 16.

Next, with reference to FIG. 2, the operation of the spread spectrum communication apparatus of the present embodiment configured as described above will be explained in detail. FIG. 2 shows the structure of one frame and the magnitude of transmission power for each information rate. First, when transmission is performed at an information rate of 8 Kbps, it is assumed that error correction encoding is performed at a coding rate of 1/4 (the information amount of encoded data for error correction with respect to information data 1 is 4). At this time, the transmission power of the control data and the transmission power of the encoded information data are made equal.

Next, when transmitting at an information rate of 16 Kbps, error correction with a coding rate of 1/2 is performed to obtain 8 Kbp.
Since the coding gain for error correction is smaller than in the case of s, the transmission power of the coded information data portion is increased so that a communication quality almost equal to 8 Kbps can be obtained.

Next, when transmitting at an information rate of 32 Kbps, error correction is not performed. Since error correction is not performed as compared with the case of 8 Kbps, the transmission power of the information data portion is increased so that communication quality almost equal to 8 Kbps can be obtained.

Next, when data is transmitted at an information rate of 64 Kbps, 32 Kbps for two channels is used for data transmission. The receiving side obtains the received data by selecting the error correction decoding method in accordance with the error correction coding method of the transmission data.

The configuration of the base station that communicates with the mobile station of the spread spectrum communication apparatus according to the first embodiment of the present invention will be described below with reference to FIG. The base station is roughly divided into an RF transceiver 55, a decoding circuit 56 corresponding to a plurality of users, an encoding circuit 57, and a control circuit 58. The RF transmitter / receiver 55 performs frequency conversion between the RF signal and the baseband signal, reception and transmission of the RF signal, and switching thereof. The decoding circuit 56 performs demodulation, quantization, despreading and decoding of the baseband signal.

The coding circuit 57 performs coding, spreading and DA conversion of transmission data. The control circuit 58 controls the entire device. In addition, a plurality of decoding circuits 56 and encoding circuits 57 are provided to support many users. The information rate switching system is the same as that of the mobile station shown in FIG. 1, and the decoding circuit 56 and the coding circuit 57 switch the error correction system having the coding rate for error correction.

Next, with reference to FIGS. 1 and 3, a method of controlling the switching of the information rate between the base station shown in FIG. 3 and the mobile station shown in FIG. 1 will be described. The switching of the information rate of each mobile station is performed by a control signal from the exchange station and a control signal between the mobile station and the base station. For example, if the user of the mobile station has not spoken for a certain period of time in the voice transmission of the uplink, the base station of FIG. 3 receives the control information transmitted from the exchange which detected it, and the control circuit 58 of the base station decodes the control information. It sends a control signal requesting the circuit 56 to switch from the next frame to the lower information rate.

Further, the control circuit 58 transmits control information for switching the information rate of the transmission signal of the mobile station from the next frame to the low speed through the encoding circuit 57 and the RF transmission / reception circuit 55 to the mobile station. The mobile station in FIG.
The signal is received through the F reception unit 3, the AD converter 4, the correlator 5, and the decoder 6, decoded, and sent to the control circuit 16. The control circuit 16 controls the encoding system selection circuit 18 and the transmission power control circuit 15 so that the information is transmitted at a low speed from the next frame.

Although this example is for the uplink, in the case of the downlink, the base station switches the information rate of the received signal according to the control data from the exchange station, and the mobile station switches the information rate of the received signal. Further, the control circuit 58 of the base station in FIG. 3 receives the control signal transmitted from the exchange station according to the traffic volume, and sends a control signal for switching the information speed of communication to the mobile station to switch the information speed. Since the number of users that the base station in FIG. 3 can accommodate changes according to the information speed of the mobile station, the number of users that can be accommodated can be increased or decreased by switching the information speed of communication.

For example, when the information speed of a signal transmitted by a certain user becomes low, the mobile station in the present embodiment increases the coding rate of error correction to increase the effect of error correction, and accordingly the transmission power is reduced. Therefore, the number of users who can make multiple access can be increased by the amount corresponding to the reduction in transmission power. Therefore, when there is a large amount of traffic due to voice transmission or the like, the information speed of each user can be reduced to accommodate many users. However, in this case, the quality of the voice is lowered to some extent. Also, when communicating at the information rate selected by the user, the mobile station can transmit control information to the base station and select the transmission rate.

The characteristics of the spread spectrum communication apparatus according to the embodiment of the present invention and the characteristics of the conventional spread spectrum communication apparatus will be compared in the following (Table 1).

[0043]

[Table 1]

As is clear from [Table 1] above, the spread spectrum communication apparatus according to the embodiment of the present invention can select the information rate for each apparatus to which multiple access is made, and the amount of traffic and user transmission. The number of mobile stations capable of multiple access efficiently changes according to the information speed of each mobile station in response to changes in the amount of information such as the presence or absence of voice, and even if the information speed of each mobile station that makes multiple access changes. An excellent effect is obtained in that data transmission can be performed while maintaining a substantially constant communication quality.

As described above, according to the first embodiment, 8 Kbps, 16 Kbps, 32 Kbps, 64 Kbps
By providing means for selecting the coding rate and decoding method for error correction according to each information rate of bps, and means for controlling the transmission power of the error correction coded information data,
The information rate can be selected to switch the information rate for each mobile station that makes multiple connections, the number of mobile stations that can be multiple-accessed can be efficiently changed, and even if the information rate changes, it is almost the same. Efficient data transmission with communication quality can be realized by the CDMA / TDD system spread spectrum communication device.

The configuration of the mobile station of the CDMA / TDD spread spectrum communication apparatus according to the second embodiment of the present invention will be described below with reference to FIG. In this embodiment, parts of the encoder and the decoder are changed,
The configuration and the operation of the first embodiment are the same as those of the first embodiment except that the operation of the control circuit 36 is different, and thus detailed description thereof will be omitted.

That is, in FIG. 4, the encoder 30 and the decoder 24 are the encoder 11 in the first embodiment.
And the decoder 6, but the encoder 31 and the decoder 25 have information rates of 4 Kbps, 2 Kbps, and 1 Kbp.
The information data corresponding to s is encoded and decoded. At an information rate of 4 Kbps, 2 Kbps, and 1 Kbps, the encoder 31 and the decoder 25 perform encoding and decoding with the same error correction method as 8 Kbps, but since the data amount is different, the frame structure is different depending on each information rate. Assemble (details will be described later).

Further, the control circuit 36 sends a control signal for selecting the encoder 31 and the decoder 25 to the encoding system selecting circuit 38 and the decoding system selecting circuit 37 in the transmission of information data of 4 Kbps or less. . Also, it sends a control signal to the transmission power control circuit 33 to control the transmission power. In addition, the control circuit 36 receives the decoded data 2
A control signal for receiving the control signal from 8 and outputting a control signal for transmitting the transmission data by shifting the frame start timing by an arbitrary time is output to the encoder 31. In the present embodiment, the encoders 30 and 31 and the control circuit 36 constitute means for providing a portion that does not transmit transmission data in one frame and means for performing communication by shifting the frame start timing by an arbitrary time. To do.

Next, with reference to FIG. 5, the operation of the spread spectrum communication apparatus of the present embodiment configured as described above will be explained in detail. Figure 5 shows 1 for each information speed
It shows the structure of the frame and the magnitude of the transmission power. First, 8K when transmitting at an information rate of 4 Kbps
The error correction coding is performed at the same coding rate 1/4 as in the case of bps. The data amount of the encoded data is 1/2 of the data amount of 8 Kbps. Therefore, as shown in FIG. 5, a burst in which data is not transmitted is set so that a frame structure is divided into a part with data and a part without data. The transmission output power of the transmitter is reduced in the portion without data, and the transmission output power is reduced to 8 Kbp in the portion with data.
Same as for s.

When transmitting at an information rate of 2 Kbps,
Coding is performed at the same coding rate of 1/4 as 8 Kbps, and the coded data amount becomes 1/4 of 8 Kbps. Therefore, as shown in FIG. 5, a burst in which data is not transmitted is set to form a frame structure in which a portion having no transmission data is provided. In the portion without data, the transmission output power of the transmitter is reduced, and in the portion with data, the transmission output power is the same as in the case of 8 Kbps.

When transmitting at an information rate of 1 Kbps,
Encoding is performed at the same encoding rate of 1/4 as 8 Kbps, and the encoded data amount becomes 1/8 of 8 Kbps. Therefore, as shown in FIG. 5, a burst in which data is not transmitted is set to form a frame structure in which a portion having no transmission data is provided. In the portion without data, the transmission output power of the transmitter is reduced, and in the portion with data, the transmission output power is the same as in the case of 8 Kbps.

Next, the transmission / reception timing of the spread spectrum communication apparatus according to the present embodiment will be described with reference to FIG. When the timings of the start of each frame of the multiple-connected devices are the same, the number of multiple-accessible devices does not change according to the information speed of each device, but as shown in FIG. By shifting the timing of frame start, the overall transmission power becomes uniform, interference between users can be reduced, and the number of devices capable of multiple access can be increased. The transmission / reception timing may be shifted by, for example, one burst unit.

In this case, the device of the base station sends a control signal designating the magnitude of shifting the frame start timing to each device which is the mobile station to which multiple access is applied, and then the device of the mobile station to which multiple access is applied. The frame start timing is shifted according to the base station, and transmission / reception is performed at the same timing.

As described above, according to the present embodiment, at the transmission rates of 4 Kbps, 2 Kbps, and 1 Kbps, the coding for setting the burst in which no data is transmitted and providing the portion without data is provided. Information rate 4 Kbps, 2 Kbps, 1 Kbps by providing a controller, a corresponding decoder, and control means for shifting the start timing of the frame for each device for multiple access.
Can be selected, and multiple devices can be efficiently connected in multiple ways. In addition, it becomes possible to select more information speeds by combining with the means of the first embodiment.

[0055]

The spread spectrum communication apparatus according to the present invention is configured as described above, and in particular, one of a plurality of coding methods having a coding rate for error correction is selected and error correction is performed on information. , A means for decoding the error-corrected coded information, a means for changing the transmission power and transmitting the information, and one of a plurality of information speeds is selected according to the information speed. By providing a means for switching between the encoding system having an error-correction encoding rate, the decoding system, and the transmission power of the information data portion, the information rate can be selected for each mobile station to which multiple access is made. A user (mobile station) that is capable of transmitting traffic volume while maintaining an almost constant communication quality regardless of changes in information speed.
Since it is possible to increase or decrease the number of users in response to changes in the amount of information such as the presence or absence of voice, it is possible to obtain a spread spectrum communication apparatus that allows multiple mobile stations to perform multiple access efficiently.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating CDMA / in a first embodiment of the present invention.
Block diagram showing the configuration of the mobile station of the TDD spread spectrum communication device

FIG. 2 is a diagram showing a frame structure and transmission power for each information rate of the spread spectrum communication apparatus shown in FIG.

FIG. 3 is a block diagram showing a schematic configuration of a base station that communicates with a mobile station of the spread spectrum communication apparatus according to the first embodiment of the present invention.

FIG. 4 is a CDMA / in a second embodiment of the present invention.
Block diagram showing the configuration of the mobile station of the TDD spread spectrum communication device

FIG. 5 is a diagram showing the configuration of one frame and the transmission power for each information rate of the spread spectrum communication apparatus according to the second embodiment of the present invention.

FIG. 6 is a diagram showing a transmission / reception timing for each mobile station in the second embodiment shown in FIG.

FIG. 7 is a block diagram showing the configuration of a conventional CDMA / TDD system spread spectrum communication device.

[Explanation of symbols]

 1, 19, 39 Antennas 2, 20, 40 Switcher 3, 21, 41 RF receiver 4, 22, 42 AD converter 5, 23, 43 Correlator 6, 24, 25, 44 Decoder 7, 26, 45 Synchronous circuit 8, 27, 46 Timing generation circuit 9, 28, 47 Decoded data 10, 29, 48 Transmission data 11, 30, 31, 49 Encoder 12, 32, 50 Spreading multiplexing circuit 13, 33, 51 DA converter 14, 34, 52 RF transmitter 15, 35, 54 Transmission power control circuit 16, 36, 53 Control circuit 17, 37 Decoding system selection circuit 18, 38 Encoding system selection circuit 55 RF transmission / reception circuit 56 Decoding circuit 57 Encoding circuit 58 Control circuit

Claims (4)

[Claims] 1. A means for converting a received RF signal into a baseband signal, quantizing, despreading, decoding and outputting decoded data, and error correction coding for transmission data, and transmission data CDMA / having means for assembling frame structure of control data, spectrum spreading to multiplex each channel, conversion to analog signal and transmission
In a TDD spread spectrum communication apparatus, a means for selecting one from a plurality of coding methods having a plurality of coding rates for error correction to perform error correction coding on information, and a means for performing the error correction coding Means for decoding the generated information, means for changing the transmission power and transmitting the information, and an encoding method and a decoding method for selecting one from a plurality of information rates and having a code rate for error correction according to the information rates A spread spectrum communication device comprising: a system and a means for switching transmission power of an information data portion, wherein the information speed is variable. 2. A means for providing a portion that does not transmit the transmission data in one frame according to the information speed, a means for reducing the transmission power of the portion to perform transmission, and a frame start for each device to be multi-accessed. 2. The spread spectrum communication apparatus according to claim 1, further comprising means for performing communication by shifting the timing of (1) by an arbitrary time. 3. Information rate 8 Kbps, 16 Kbps and 3
A means for selecting an information rate from 2 Kbps and an error correction coding rate of 1/4 or 1 / corresponding to the selected information rate.
2 and means for performing switching error correction coding without error correction, means for decoding error correction coded information, and means for switching the transmission power of the information data portion corresponding to the information speed. The spread spectrum communication device according to claim 1 or 2, further comprising: 4. Information speed 8 Kbps, 4 Kbps, 2 Kb
ps, 1 Kbps, a means for selecting an information rate, a means for forming a portion having no information data in a frame with a data amount corresponding to the selected information rate and reducing the transmission power of the portion, and multiple connection is performed. The spread spectrum communication device according to claim 1, 2 or 3, further comprising means for shifting the frame start timing for each device and transmitting the frame.