JP3001366B2 - Wireless communication method using TDMA system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a TDMA (Time Divis
The present invention relates to a bidirectional wireless communication method at a single frequency using an ion multiple access (time division multiplex access) method.

[0002]

2. Description of the Related Art A radio apparatus has been developed and put to practical use for performing bidirectional communication at a single frequency for maintenance work in a power company or the like. This is achieved by reducing the audio bandwidth in an analog manner.

[0003]

However, such a mobile radio device has a narrow audio bandwidth in an analog system to enable two-way communication at a single frequency, thereby deteriorating sound quality and providing good clarity. There was a problem that communication was not possible. Therefore, an object of the present invention is to provide a wireless communication method capable of performing bidirectional communication with a single frequency and good clarity.

[0004]

The radio communication method according to the present invention uses a time division multiplexing connection system in which an allocated time slot is constituted by a control slot for transmitting control data and a communication slot for transmitting communication data. Wireless communication method, wherein one of the two communication stations transmits control data at the front end of the time slot, and the other of the two communication stations at the rear end of the time slot. Transmits control data, one station or the other station transmits full-rate communication data using all of the communication slots in the one-way communication mode in the middle part of the time slot, and one station in the two-way communication mode. Transmits half-rate communication data using half of the communication slot, and then the other station transmits half-rate communication data using the other half of the slot. It is characterized by transmitting the data.

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings. In the mobile radio apparatus of the TDMA system according to the present invention shown in FIG. 1, the antenna 1 is a transmitting / receiving antenna and employs a TDD (Time Division Duplex) system. The terminal of the antenna 1 is connected to one of the receiving unit 3 and the transmitting unit 4 via the antenna switch 2. The selection of the antenna switch 2 on the receiving unit 3 side is in a steady state. In the receiving unit 3, a high-frequency signal, which is a signal received from the antenna switch 2, is subjected to a band limiting filter
F) After being band-limited by 5, the signal is supplied to the high-frequency amplifier 6. The signal amplified by the high frequency amplifier 6 is supplied to a down converter 8 via a band limiting filter 7. The down-converter 8 applies V
The local oscillation signal from CO9 is mixed to generate an intermediate frequency signal. The intermediate frequency signal output from the down converter 8 is digitized by the A / D converter 10,
The signal is supplied to a DSP (Digital Signal Processor) 11. The DSP 11 detects the supplied digitized intermediate frequency signal, demodulates information signals such as a voice signal and a control signal included in the received signal, and supplies the demodulated information signal to the channel coder / decoder 12. The DSP 11 performs a modulation operation according to communication data, which is a digital information signal to be transmitted, supplied from the channel coder / decoder 12 and supplies the result of the modulation to the transmission unit 4.

[0006] In the transmission section 4, the digital signal output from the DSP 11 is supplied to an up-converter 14 via a D / A converter 13. Upconverter 14
Mixes the modulated signal with the oscillation signal from the VCO 15 and converts the frequency to the frequency to be transmitted. The oscillation signal is amplified by the pre-amplifier 16 and further amplified by the power amplifier 17 to become a transmission signal. This transmission signal is supplied to the antenna 1 via the antenna switch 2.

The modulation and demodulation operations of the DSP 11 are performed by a CPU.
(Central processing unit) 19. The switching operation of the antenna switch 2, the oscillation frequencies of the VCOs 9 and 15, and the amplification operation of the power amplifier 17 are controlled by the operation state of the DSP 11. The CPU 19 controls the DSP 11 according to the operation from the keyboard 20, and also controls the channel coder / decoder 12 and the voice CODEC (codec).
21 are controlled. The channel coder / decoder 12 operates as a coder for performing a predetermined code conversion on a digital audio signal supplied from the voice CODEC 21 or a digital data signal supplied from the data input / output interface 22, and performs a signal conversion after the code conversion. Is supplied to the DSP 11. Further, it performs an operation as a decoder for decoding the demodulated digital signal supplied from the DSP 11 and supplies the decoded digital signal to the voice CODEC 21 or the data input / output interface 22. The voice CODEC 21 converts an analog audio signal from the microphone amplifier 23 into a digital audio signal in a predetermined format, converts the decoded digital audio signal from the channel coder / decoder 12 into an analog signal, and converts the analog audio signal into an analog signal.
To supply. A microphone 25 is connected to the microphone amplifier 23, and a speaker 26 is connected to the speaker amplifier 24.
Is connected.

In the mobile radio apparatus having such a configuration, for example, the output of the power amplifier 17 of the transmitting unit 4 is increased at a predetermined timing in a time slot allocated from the base station as shown in a waveform of FIG. Later reduction is performed. In FIG. 2, four TDs
It shows the MA system, and wireless communication is performed between a base station and the same mobile station at each position having the same slot number. For example, the slot is configured to transmit data of 320 bits with a length of 20 msec. In each slot, control channels (control data) of both stations performing communication are located at both ends as schematically shown in FIG.

The communication mode includes a one-way communication mode and a two-way communication mode. In each communication mode, the control channel of one station is located at the leading end of the slot, and the control channel of the other station is the slot. Located at the rear end.
As shown in FIG. 4, the data format in the slot in the one-way communication mode includes a ramp at the start of transmission from one station (up), a unique word serving as a synchronization signal, control data, and a CRC (cyclic redundancy) for error detection. Inspection), full-rate communication data, and ramp at the end of transmission. After the ramp at the falling edge of the transmission, a guard time for 8 bits is set. After the guard time, a ramp at the rising edge of transmission from the other station (downstream) side, a unique word serving as a synchronization signal, control data, a CRC for error detection,
Then, the ramp of the transmission fall is in order. Further, a guard time for 8 bits is set between the next slots. In the figure, the numbers in parentheses are the number of bits.

As shown in FIG. 5, the data format in the slot in the bidirectional communication mode includes a ramp at the start of transmission from one station (up), a unique word serving as a synchronization signal, control data, and a CRC for error detection. , Half-rate communication data, and the ramp at the end of transmission. After the ramp at the falling edge of the transmission, a guard time for 8 bits is set. After the guard time, similarly from the other station (downstream) side, a ramp at the rising edge of the transmission, a unique word serving as a synchronization signal, control data, half-rate communication data, a CRC for error detection, and a ramp at the falling edge of the transmission. Becomes Further, a guard time for 8 bits is set between the next slots.

In the data formats of the one-way communication mode and the two-way communication mode, the control data is control channel data. The control data to be transmitted is first supplied from the CPU 19 to the channel coder / decoder 12, is converted into the above data format together with the communication data from the voice CODEC 21 or the data input / output interface 22, and then supplied to the DSP 11.
Note that communication data is not included until a link is established. The DSP 11 performs data conversion on the supplied data signal by a modulation operation and supplies the data signal to the D / A converter 13. D
The data signal analogized by the / A converter 13 is superimposed on the oscillation signal from the VCO 15 by the up-converter 14. The oscillation signal including the data signal is supplied to the pre-amplifier 16
, And is further amplified by the power amplifier 17 to become a transmission signal, which is supplied to the antenna 1 via the antenna switch 2. On the other hand, the signal received by the antenna 1 is supplied to the down converter 8 via the antenna switch 2, the band limiting filter 5, the high frequency amplifier 6, and the band limiting filter 7. In the down converter 8, the supplied signal is mixed with the local oscillation signal from the VCO 9 to become an intermediate frequency signal, which is digitized by the A / D converter 10 and supplied to the DSP 11. DSP11
Is supplied to the channel coder / decoder 12. The channel coder / decoder 12 supplies control data to the CPU 19, and transmits communication data to the voice CODEC.
21 or the data input / output interface 22.
That is, if the communication data is voice data, it is supplied to the voice CODEC 21, and if it is not voice data, it is supplied to the data input / output interface 22.

FIG. 6 shows an operation until communication is performed in the two-way communication mode. When communication is started, a transmission signal including control data for a link establishment request is transmitted from the antenna 1 in the one-way communication mode by operating the keyboard 20 on the calling side. When the response side determines a link establishment request for control data obtained from the received signal, a transmission signal including the control data of the link establishment response is transmitted from the antenna 1 in the one-way communication mode.
Upon receiving the link establishment response, the calling side starts communication in the one-way communication mode. Here, as shown in FIG. 4, full-rate communication data is included. In response to the communication in the one-way communication mode, the response side performs a full-rate communication response in the one-way communication mode using control data.

If the responding side desires data transmission to the calling side during communication in the one-way communication mode, a transmission signal including control data for a two-way communication mode request is transmitted from the antenna 1 by operating the keyboard 20. Is done. On the calling side, when the control data obtained from the received signal determines the bidirectional communication mode request, the transmitting signal including the control data of the bidirectional communication mode response is transmitted from the antenna 1. After the transmission of the transmission signal is completed, the communication mode is switched from the one-way communication mode to the two-way communication mode on the calling side. When the response side determines the bidirectional communication mode response from the received control data, the communication mode is switched to the bidirectional communication mode, and communication in the bidirectional communication mode is started. Here, as shown in FIG. 5, half-rate communication data is included, and the transmission time is about half of one time slot. When the communication within one slot in the two-way communication mode is completed, the response side generates a half-rate communication response in the two-way communication mode, and thereafter, the communication in the slot two-way communication mode is repeated in the assigned slot. It is.

That is, upon outputting the control data of the bidirectional communication mode request, the CPU 19 of the responding apparatus determines whether the control data has been newly received. When new control data is obtained, it is determined whether or not the control data indicates a bidirectional communication mode response. When the response indicates the bidirectional communication mode, the operation of the channel coder / decoder 12 and the voice CODEC 21 is switched to the bidirectional communication mode. When the response does not indicate the bidirectional communication mode, the operation of the channel coder / decoder 12 and the voice CODEC 21 is switched.
The operation of the DEC 21 is maintained in the unidirectional mode.

When the control data of the request for the bidirectional communication mode is obtained, if the communication in the bidirectional communication mode is not possible, the CPU 19 of the calling device automatically or in response to an operation from the keyboard 20. To perform a two-way communication mode response, and then the channel coder / decoder 1
2 and the operation of the voice CODEC 21 are switched to the two-way communication mode.

Further, during the two-way communication mode, one station issues a request to shift to the one-way communication mode, and if the other station agrees, the same procedure as described above is performed on the control channel to perform the one-way communication. It switches to the communication mode.

[0017]

As described above, in the radio communication method using the TDMA system of the present invention, one of the communication stations transmits control data to the front end of the time slot, and the rear end of the time slot. The other station of both communication stations transmits control data, one station or the other station transmits full rate communication data in the one-way communication mode in the middle part of the time slot, and in the two-way communication mode One station sends half-rate communication data, and then
Since the other station transmits half-rate communication data,
Since information compression is performed by using the DSP, the audio bandwidth does not need to be narrowed unlike the conventional method, and two-way communication can be performed at a single frequency and with good clarity.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a wireless communication device to which a wireless communication method of the present invention is applied.

FIG. 2 is a diagram showing time slots used for transmitting information in a TDMA system.

FIG. 3 is a diagram illustrating a position of a control channel in a time slot.

FIG. 4 is a diagram showing a data format in a slot in a one-way communication mode.

FIG. 5 is a diagram showing a data format in a slot in a bidirectional communication mode.

FIG. 6 is a diagram showing an operation sequence until communication is performed in a two-way communication mode.

[Explanation of Signs of Main Parts]

 Reference Signs List 1 antenna 3 receiver 4 transmitter 11 DSP 12 channel coder / decoder 19 CPU 21 voice CODEC

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04L 5/16 H04J 3/00

Claims (3)

(57) [Claims] 1. A wireless communication method using a time-division multiplexing access system in which an assigned time slot includes a control slot for transmitting control data and a communication slot for transmitting communication data. One of the two communication stations transmits control data to the front end, the other of the two communication stations transmits control data to the rear end of the time slot, and the time In the one-way communication mode in the middle part of the slot, the one station or the other station transmits full-rate communication data using all of the communication slots, and in the two-way communication mode, the one station transmits the full-rate communication data. The half station transmits half-rate communication data using the other half, and then the other station transmits half-rate communication data using the other half of the slot. Wireless communication method. 2. The communication system according to claim 1, wherein the one station is connected to all the communication slots.
In the one-way communication mode in which full-rate communication data is transmitted using the other station, the other station transmits control data indicating a bidirectional communication mode request, and the one station determines a bidirectional communication mode request from the received control data. And transmitting the control data indicating the bidirectional communication mode response to the bidirectional communication mode, and transiting to the bidirectional communication mode when the other station determines the bidirectional communication mode response from the received control data. The wireless communication method according to claim 1, wherein: 3. The one station in the two-way communication mode is a single station.
When transmitting control data indicating the rectangular direction communication mode request
The other station determines a one-way communication mode request from the received control data, and when responding to it, transmits control data indicating a one-way communication mode response and shifts to a one-way communication mode, and the one station 2. The wireless communication method according to claim 1, wherein a transition is made to a one-way communication mode when a one-way communication mode response is determined from the received control data.