JPH098782A - Radio communication system for tdma system - Google Patents

Abstract

PURPOSE: To exactly read received data without wasting communication resources by transmitting a radio signal, for which a unique word is thinned according to prescribed rules, from one of both stations at least. CONSTITUTION: A CPU 19 calculates the frequency to require the unique word by providing a synchronizing signal from a synchronizing error signal measured for a fixed period by a synchronizing error measuring circuit. Then, the CPU 19 sends a ratio signal containing the calculated frequency in control data. Thus, the transmission frequency of the unique word is transmitted to the confronting station. Next, a channel coder/decoder 12 is commanded for changing the mode into a thinning mode in which the unique word is transmitted with the calculated frequency. In a data format which does not constitute any unique word, the section of the unique word is replaced with communication data or control data. Thus, the received data can exactly be read without wasting the communication resources.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to TDMA (Time Divis).
ion multiple access: relates to a wireless communication system using a time division multiple access method.

[0002]

2. Description of the Related Art In a TDMA type wireless communication system, when a mobile wireless station is used in a base station communication area, first, a burst signal sent from the base station is transmitted from a base station at the time of power-on of the wireless device. Upon reception, the unique word in the burst signal is detected, and if the unique word matches the one desired by the mobile radio station, the information in the burst signal can be read to discover the base station and start communication. it can. The unique word also has a function as a position reference for frame synchronization, and is composed of at least 16 bits, usually 32 bits or more for each time slot. The receiving side uses the timing when a unique word is detected for each time slot to establish frame synchronization in that time slot, thereby detecting the specified position of each bit in the frame and reading the received data. There is.

[0003]

By the way, one time slot is composed of about 200 bits, and if a unique word of 32 bits is used for this, 16% of communication resources contribute to communication. It will be used in vain without doing it. If the unique word is 64 bits, communication resources are further wasted. However, if the frame synchronization is not accurately obtained using the unique word, a bit shift of the received data will occur, making it impossible to read the accurate data.

SUMMARY OF THE INVENTION An object of the present invention is to provide a radio communication system using the TDMA method, which can accurately read received data with accurate frame synchronization without wasting communication resources.

[0005]

A wireless communication system of the present invention uses a time division multiplex connection method in which both stations wirelessly communicate at a predetermined time slot in each frame, and a wireless signal transmitted from a partner station. Is a system for reading data from the received wireless signal by frame synchronization based on the reception timing of the unique word included in the received wireless signal, and at least one station of both stations has a predetermined rule. It is characterized by transmitting a wireless signal in which the unique word is thinned out according to.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. In the wireless device using the wireless communication system of the present invention shown in FIG. 1, the antenna 1 is a transmitting / receiving antenna, and the TDD (Time Division Duplex) system is adopted. The terminal of the antenna 1 is connected to either the receiving unit 3 or 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, the high frequency signal which is the received signal from the antenna switch 2 is band-limited by the band limiting filter (BPF) 5 and then supplied to the high frequency amplifier 6. The signal amplified by the high frequency amplifier 6 is supplied to the down converter 8 via the band limiting filter 7. The down converter 8 mixes the supplied high frequency signal with the local oscillation signal from the VCO 9 to generate an intermediate frequency signal. The intermediate frequency signal output from the down converter 8 is digitized by an A / D converter 10 and then supplied to a DSP (digital signal processor) 11. The DSP 11 detects the supplied digitized intermediate frequency signal, demodulates an information signal 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 also performs a modulation operation according to a data signal, which is a digital information signal to be transmitted, supplied from the channel coder / decoder 12, and supplies the modulation result to the transmission unit 4.

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

The modulation and demodulation operations of the DSP 11 are performed by the CPU
It is controlled by (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 operating state of the DSP 11. The CPU 19 controls the DSP 11 according to the operation from the keyboard 20, and also controls the operation modes of the channel coder / decoder 12 and the voice CODEC (codec) 21. The channel coder / decoder 12 is a digital audio signal or data input / output interface 2 supplied from the voice CODEC 21.
It operates as a coder that performs a predetermined code conversion on the digital data signal supplied from the signal No. 2, and supplies the signal after the code conversion to the DSP 11. Also, DSP
An operation as a decoder for decoding the demodulated digital signal supplied from 11 is performed and the decoded digital signal is supplied to the voice CODEC 21 or the data input / output interface 22. The voice CODEC 21 converts the analog audio signal from the microphone amplifier 23 into a digital audio signal of a predetermined format, converts the decoded digital audio signal from the channel coder / decoder 12 into an analog signal, and supplies it to the speaker amplifier 24. To do. A microphone 25 is connected to the microphone amplifier 23, and a speaker 26 is connected to the speaker amplifier 24.

The data to be transmitted is first supplied from the CPU 19 to the channel coder / decoder 12, and the voice CO
The data is converted into a data format according to the operation mode together with the communication data from the DEC 21 or the data input / output interface 22, and then supplied to the DSP 11. Communication data is not included until the link is established. As the operation mode, there are a normal mode and a thinning-out mode as described later, but the communication mode is set to operate in the normal mode. 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. The data signal analogized by the D / 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 amplified by the pre-stage amplifier 16 and further amplified by the power amplifier 17 to become a transmission signal, and the antenna switch 2
Is supplied to the antenna 1 via the. 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. 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 then supplied to the DSP 11. The signal demodulated by the DSP 11 is a channel coder /
The data is supplied to the decoder 12. The channel coder / decoder 12 supplies control data to the CPU 19 and 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 the data input / output interface 22.
Is supplied to.

The radio apparatus having such a configuration is used in both the base station and the mobile station, and in the radio apparatus, the channel coder / decoder 12 has a synchronization error measuring circuit. As shown in FIG. 2, the synchronization error measuring circuit is provided with a shift register 31 to which the data signal from the DSP 11 is supplied. Shift register 31
Shifts while holding n-bit data in synchronization with a master clock pulse generated from a clock generation circuit 30 including a PLL (Phase Locked Loop) circuit, and the n-bit held output is the digital comparison circuit 32. Is supplied to. A memory 33 in which a predetermined unique word is stored in advance is connected to the digital comparison circuit 32, and an output of a frequency divider 34 that divides the master clock pulse by a frequency division ratio of 1/100 is also connected. The comparator circuit 32 compares the output data held in the shift register 31 with a predetermined unique word stored in the memory 33 in synchronization with the frequency-divided clock pulse output from the frequency divider 34, and when they match, a match pulse is output. To occur. The coincidence pulse is supplied to the clock pulse generation circuit 30, and the phase of the coincidence pulse is compared with a reference clock generated from a reference oscillator (not shown) to adjust the generation timing of the master clock pulse. This adjusts the frame synchronization. That is, since the DSP 11 and the channel coder / decoder 12 operate in synchronization with the master clock pulse, the bitwise reading timing of the received data is compensated.

A counter 35 is provided at the output of the frequency divider 34.
Is connected to the counter 35, and the counter 35 supplies a reset pulse indicating the start of a predetermined time slot determined by the counting of the master clock pulse from the CPU 19 each time.
The divided clock pulse is counted from the initial value and the counted value is output to the flip-flop 36. Flip-flop 3
Reference numeral 6 holds the count value of the counter 35 when the coincidence pulse is generated and outputs a sync error signal indicating the held value as a sync error. The synchronization error signal is supplied to the CPU 19.

In the wireless communication system using the wireless device having such a configuration, the power amplifier (power amplifier) 17 of the transmitter 4 has a predetermined time slot assigned by the base station, for example, as shown in the waveform of FIG. The output is increased at a specified timing and decreased after a specified time. FIG. 4 shows allocation of time slots used in wireless communication between a base station and one mobile station in the case of the quadruple TDMA method, and at positions with the same slot number (slot number 1 in FIG. 4). In (), wireless communication is performed between the base station and the same mobile station.
The up period is a communication period from the mobile station to the base station, and the down period is a communication period from the base station to the mobile station. One frame consists of one down period and one up period that follows it.
A guard time is placed between the adjacent slots.

As a slot data format, the data format in the control channel is, for example, as shown in FIG.
As shown in, the ramp time (R) for transient response, the preamble for synchronization (PR), the unique word (UW), the destination identification code (DA) that is the calling code of the partner station, and the calling of the own station in order from the slot head A calling identification code (OA) that is a code,
It consists of control data such as link channel allocation, and error detection additional information (CRC). Similarly, as the format of slot data, the format in the communication channel is, as shown in FIG. 6, a ramp time (R) for transient response, a preamble for synchronization (PR), a unique word (UW), communication data in order from the beginning of the slot. , And error detection additional information (CRC).

FIG. 7 shows the operation until communication is performed. When a call is received or a call is made, a transmission signal including control data of a link establishment request is transmitted from the antenna 1 by operating the keyboard 20 in the mobile station. In response to a link channel establishment request from the mobile station to the base station on the control channel, the base station may transmit a transmission signal including control data of a link establishment response from the antenna 1 to perform link channel allocation to the mobile station. Done. After switching to the communication channel by the link establishment response, the operation is performed by supplying the synchronization burst from the mobile station to the base station, supplying the synchronization burst from the base station to the mobile station, and the communication mode setting request from the mobile station to the base station. Supply,
Response to communication mode setting from base station, supply of call setting request from mobile station to base station, response to call setting from base station, supply of function / authentication request from base station to mobile station, supply from mobile station A call is made after a response to the function / authentication request, a call from the base station to the mobile station, and a response.
These are transmitted as data in slots.

The CPU 19 obtains a sync error from the sync error signal measured by the sync error measuring circuit over a constant period (for example, 1 second) in the control channel or the communication channel as shown in FIG. 8 (step S1). ),
The frequency of requiring a unique word is calculated from the synchronization error (step S2). For example, if the synchronization error is greater than a predetermined value, the frequency is calculated once per frame, and if the synchronization error is less than the predetermined value, the frequency is calculated once every two frames. The CPU 19 sends out a wireless signal including the calculated frequency in the control data (step S).
3). As a result, the transmission frequency of the unique word is transmitted to the partner station. Then, the channel coder / decoder 12 is instructed to change to the thinning mode for transmitting the unique word at the frequency calculated from the next frame (step S4). In the decimation mode, when the calculated frequency is once every two frames, the channel coder / decoder 12 configures the unique word once in every two frames, that is, every other frame in the data format (FIG. 5 or FIG. 6). To do. In a data format that does not form a unique word, the unique word portion is replaced with communication data or control data.

When the CPU 19 confirms the transmission frequency of the transmitted unique word in the partner station, it instructs the channel coder / decoder 12 to configure the unique word in the data format in the thinning mode of the frequency.
The unique word exists to determine the reception data read timing for each bit by the master clock pulse, and as described above, the clock generation circuit 30 is responsive to the coincidence pulse generated at the reception timing of the unique word.
The timing of generation of the master clock pulse generated from is adjusted. Therefore, since the unique word is thinned out and the radio signal is transmitted in the predetermined data slot, in the frame in which the unique word does not exist in the signal of the received time slot, the clock generation circuit 30 is adjusted in the previous frame. The generation timing of the master clock pulse is maintained as it is.

The synchronization error may be measured by either one of the base station and the mobile station in communication, and
Even if one station transmits the unique word transmission frequency to the other station and the other station transmits confirmation that the unique word transmission frequency is confirmed, it actually shifts to the thinning mode to thin out the unique words. good. Also, if the synchronization error becomes larger than the predetermined value in the mode of transmitting the unique word at a frequency of once in a plurality of frames, after notifying the partner station that the transmission frequency of the unique word is changed to the normal mode. Alternatively, a unique word may be inserted in each frame.

Further, in the above-mentioned embodiment, it is a normal mode that a unique word is transmitted in each frame when communication is started, but it is known in advance that both communication stations use the thinning mode. If so, the thinning mode can be used from the start of communication.
Further, the transmission frequency of the unique word is not limited to once in a plurality of frames such as once in three frames, but it is not necessary to transmit the unique word every two frames.
The number of even-numbered times n (m> n) may be set to a plurality of odd-numbered frames m such as 1 degree (two frames every other frame).

Furthermore, it is not necessary for both stations communicating by radio to transmit a radio signal containing no unique word for at least one frame every predetermined number of frames, and only one station includes such a unique word. You may make it transmit a wireless signal which does not exist.

[0020]

As described above, in the wireless communication system of the present invention, at least one station of both stations performing wireless communication transmits a wireless signal with a unique word thinned out according to a predetermined rule. In place of the unique word, control data and communication data can be further inserted in the. Also, the accuracy of the master clock is, for example,
If it is as high as 0.5 ppm, for example, even if a radio signal including a unique word is transmitted in only one frame for every 10 frames and the read timing of the received data is not adjusted for each frame, it is sufficiently accurate. Frame synchronization can be maintained. Therefore, according to the present invention,
The received data can be read accurately without wasting communication resources.

[Brief description of drawings]

FIG. 1 is a block diagram showing a wireless device to which the present invention has been applied.

FIG. 2 is a block diagram showing a configuration of a synchronization error measuring circuit.

FIG. 3 is a diagram showing a change in transmission power in a time slot.

FIG. 4 is a diagram showing time slot allocation in the case of a quadruple TDMA method.

FIG. 5 is a diagram showing a data format of a radio signal in a control channel.

FIG. 6 is a diagram showing a data format of a radio signal in a communication channel.

FIG. 7 is a diagram showing a control sequence until a call is made.

8 is a flowchart showing an operation of a CPU in the apparatus shown in FIG.

[Explanation of symbols for main parts]

 1 Antenna 3 Receiver 4 Transmitter 11 DSP 12 Channel Coder / Decoder 19 CPU 21 Voice CODEC 22 Data Input / Output Interface

Claims (8)

[Claims] 1. A time division multiplex connection system in which both stations wirelessly communicate within a predetermined time slot in each frame, receives a radio signal transmitted from a partner station, and includes it in the received radio signal. A wireless communication system for reading data from the received wireless signal in frame synchronization based on the reception timing of the unique word, wherein at least one of the two stations thins out the unique word according to a predetermined rule. A wireless communication system, which transmits a wireless signal. 2. A frame synchronization error is measured from the reception timing of the unique word when the unique word is included in a radio signal for each frame, and the transmission frequency of the unique word is set according to the measured synchronization error. The wireless communication system according to claim 1, wherein: 3. A clock generating means for generating a master clock pulse, a shift register of a plurality of bits for sequentially holding data in the received radio signal in synchronization with the master clock pulse, and a memory storing the unique word in advance. Comparing means for generating a coincidence pulse when the data held in the shift register coincides with the unique word stored in the memory; and means for generating a reset pulse indicating the start time point of the predetermined time slot,
Frequency dividing means for dividing the master clock pulse, a counter for counting the divided clock pulses reset in response to the reset pulse and outputted from the dividing means, and a counter for counting the coincident pulse. The wireless communication system according to claim 2, further comprising a holding unit that holds the count value as a synchronization error. 4. The wireless communication system according to claim 2, wherein a wireless signal including the set transmission frequency of the unique word as data is transmitted to a partner station. 5. The data format of the radio signal including the unique word is a ramp at the start of transmission in the control channel, a preamble, the unique word, a destination identification code which is the calling code of the partner station, and a calling identification which is the calling code of the own station. A code, control data, and additional information control data for error detection are arranged in this order. In a communication channel, a ramp at the start of transmission, a preamble, the unique word,
2. The wireless communication system according to claim 1, wherein the communication data is followed by the error detection additional information control data. 6. The wireless communication system according to claim 1, wherein other data is inserted in place of the unique word in the wireless signal thinned out of the unique word. 7. The wireless communication system according to claim 6, wherein the other data is control data or communication data. 8. A time division multiplex connection method in which both stations wirelessly communicate within a predetermined time slot in each frame is used, and a radio signal transmitted from a partner station is received and included in the received radio signal. A wireless device that reads data from the received wireless signal in frame synchronization based on the reception timing of the unique word, wherein at least one of the two stations is a wireless device that thins out the unique word according to a predetermined rule. A wireless device characterized by transmitting a signal.