JPH09172403A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently execute resending control by leaving transmission data in a buffer for a fixed time after transmission and requiring resending to a transmission terminal when a reception terminal can not correctly receive data. SOLUTION: In a radio adapter 402, a radio part 403 communicates with a centralized control station and a radio private telephone equipment and data assembled to be a frame by a channel codec 408 is transmitted to the centralized control station and a confronting terminal through the radio part 403. An error correction processing part 409 inserts an error correction code in communication data at the time of transmission and corrects an error position and an erroneous pattern by arithmetic processing at the time of reception. When the error correction processing part 409 can not correct data, a resending control part 412 prepares a resending request frame and executes resending processing. A transmission counter 413 and a reception counter 414 check the transmission and reception of data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication network, and more particularly to a frequency hopping system (F
H system) spread spectrum communication (SS: Spread)
(Spectrum), characters, voice, images,
The present invention relates to a system for simultaneously transmitting multimedia data such as video to a plurality of terminals.

[0002]

2. Description of the Related Art In recent years, wireless communication has rapidly progressed and has been used in various fields. In particular, a system for wirelessly performing multimedia data communication has been proposed.

Further, even in the above wireless switching systems, those using a digital wireless system as a wireless system have been increasing. Spread spectrum communication is of particular interest among digital wireless communication systems.

[0004] Spread-spectrum communication is known as a technique that spreads information to be transmitted over a wide band, has a high interference removal capability, and is excellent in secrecy. In countries around the world,
A frequency in the 4 GHz band is allocated for spread spectrum communication, and is spreading worldwide.

[0005] Spread spectrum communication systems can be roughly divided into frequency hopping (FH system) and direct spread (DH).
S method). The former is to transmit over a wide band by changing the modulation frequency within a certain period of time, and the latter is to perform an extended conversion of the information to be transmitted with a pseudo-noise code whose speed is ten to several hundred times faster. To use a wider band.

[0006] In the spread spectrum communication system of the FH system, a plurality of communications can be performed simultaneously depending on the shape of the modulation frequency change (hopping pattern: HP). That is, the communication multiplexed at the same time can be realized by the communication terminals communicating with different HPs.

In the conventional FH wireless multimedia communication system, when one terminal communicates with a plurality of terminals by time division multiplexing or when communicating data of a plurality of media, HP is assigned to each terminal. ,
This has realized multiplex communication.

[0008]

However, the above-mentioned conventional example has the following problems.

(1) In the case of wireless communication, the data transmission error rate is higher than that in wired communication, and an error correction means is required.

(2) When performing multimedia communication, depending on the type of data, it is necessary to send accurate data with certainty, such as file data transfer, and new data such as video real-time data. May have to be sent. In such a situation, it was not possible to select whether or not to retransmit the data.

(3) Communication for transmitting data to be retransmitted and communication for sequentially transmitting new data without retransmitting cannot be performed at the same time.

(4) If data is stored in the buffer without being erased so that data can be always retransmitted, a huge buffer memory is required.

It is an object of the present invention to provide a wireless communication system capable of performing efficient retransmission control, reducing the error rate and improving the buffer memory efficiency.

[0014]

Means for Solving the Problems The first invention of the present application is:
A spread spectrum wireless communication means using a frequency hopping system is provided, and a centralized control station for setting up a call when terminals in the system perform communication and a communication terminal having means for SS wireless communication with the centralized control station are provided. In the wireless communication system configured as described above, when the communication terminal communicates data, a means for leaving the data in the buffer for a certain period of time after the transmission side communication terminal finishes transmitting the transmission data, and a receiving side. It has means for requesting a retransmission to the transmitting communication terminal when the communication terminal cannot correctly receive the data, and means for retransmitting the corresponding data when the transmitting communication terminal receives the retransmission request. Characterize.

In the second invention of the present application, the communication terminal includes means for adding a header as control data to a transmission data frame, means for setting a flag in the header to indicate whether or not retransmission is possible, and reception. The side communication terminal is characterized by having means for not issuing a resend request even when the data containing the flag of non-retransmission is received even if the data is not correctly received.

The third invention of the present application is characterized in that the communication terminal has means for switching and transmitting a flag indicating whether data can be retransmitted even within one communication.

In the fourth invention of the present application, the transmission side communication terminal has means for erasing the transmission data from the buffer immediately after the transmission when the non-retransmittable data is transmitted. .

In the wireless communication system configured as described above, the error rate can be reduced by the retransmission control, and in one communication, the communication for transmitting the data to be retransmitted and the new data are sequentially transmitted without retransmitting. Power communication can be performed simultaneously. Further, the buffer memory can be used efficiently.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, a detailed description will be given of a case where digital radio communication based on a frequency hopping method is used for extension transmission of a switching system.

FIG. 1 is an explanatory diagram showing the configuration of a system assumed in this embodiment.

This system comprises a centralized control station 101 having a wireless connection function between respective wireless terminals, a plurality of wireless dedicated telephones 102-A for communicating control data and voice data,
102-B, data terminal devices 103-A to 103-A for performing communication of control data and direct data communication between terminals.
F.

The definition of the data terminal device in the present embodiment is that "a terminal (data terminal) having a function of transmitting an arbitrary amount of data in a burst and a wireless adapter for controlling wireless communication between the data terminals are combined. The data terminal is not limited to the computer 103-A,
Various terminals that perform data processing, such as a printer 103-B, a copier 103-C, a video conference terminal 103-D, a facsimile 103-E, a LAN bridge 103-F, an electronic camera, a video camera, and a scanner are applicable. .

FIG. 2 is a block diagram showing the configuration of the centralized control station 101.

The CPU 201 is the center of the centralized control station 101, and controls the entire centralized control station 101 including the control of speech channels and the control of the radio section. ROM 202
Is a program storing a control program for the CPU 201, and the EEPROM 203 stores a call code (system ID) of the present exchange system. RAM
204 stores various data for controlling the CPU 201 and provides a work area for various calculations.

The channel codec 205 has a CPU 20.
Under the control of 1, the control signal is subjected to processing such as scrambling, and time-division multiplexed into a predetermined frame. Under the control of the CPU 201, the radio unit 206 modulates the framed digital signal from the channel codec 205 so that it can be transmitted wirelessly, transmits it to the antenna, and demodulates the signal received wirelessly from the antenna. Then, the digital signal is processed into a framed digital signal.

FIG. 3 is a block diagram showing the configuration of the wireless telephone 102.

The CPU 301 is the center of the wireless-only telephone 102, and controls the entire wireless-only telephone 102 including control of the radio section and call control. ROM 302
Indicates that the control program of the CPU 301 is stored, and the EEPROM 303 stores the calling code (system ID) of the exchange system and the sub ID of the wireless dedicated telephone. The RAM 304 stores various data for controlling the CPU 301 and provides a work area for various calculations.

The call circuit 305 inputs / outputs a call signal from a handset 310, a microphone 311, and a speaker 312, which will be described later, under the control of the CPU 301.
The PCM codec 306 is under the control of the CPU 301.
The analog voice signal from the communication circuit 305 is converted into an ADPCM code and transmitted to a channel codec 307, which will be described later.
It is an ADPCM codec for converting an M-coded call signal into an analog voice signal and transmitting it to a call circuit.

The channel codec 307 is a CPU 30.
Under the control of No. 1, processing such as scrambling is performed on the communication signal and the control signal that have been ADPCM-coded, and time-division multiplexing is performed on a predetermined frame.

Under the control of the CPU 301, the radio section 308 modulates the framed digital signal from the channel codec 307, processes it so that it can be transmitted by radio, and transmits it to an antenna described later. The received signal is demodulated and processed into a framed digital signal.

The handset 310 is for inputting / outputting a voice signal for talking, and the microphone 311 is for collecting and inputting a voice signal. The speaker 312 outputs the audio signal in a loud voice. The display unit 313 displays a dial number input from a key matrix, which will be described later, and the usage status of external lines.

The key matrix 314 is composed of dial keys for inputting dial numbers and the like, and function keys such as an outside line key, a hold key, and a speaker key. The HP storage register 315 stores the moving frequency.

FIG. 4 is a block diagram showing the internal structure of the wireless adapter connected to the data terminal.

In the figure, a data terminal 401 is, for example, a personal computer, a workstation, a printer, a facsimile, or other data terminal equipment connected to the wireless adapter 402 via a communication cable or an internal bus.

Further, in the wireless adapter 402, the wireless unit 403 includes a central control station 101 and a wireless telephone 1.
02 has the same configuration as the wireless unit and performs wireless communication with these wireless units.

The main control unit 404 is composed of a CPU, peripheral devices for performing interrupt control, DMA control, etc., an oscillator for the system clock, etc., and controls each block in the wireless adapter.

The memory 405 is composed of a ROM for storing programs used by the main control unit 404, a RAM used as a buffer area for various processes, and the like.

The communication i / f section 406 is a communication i / f that is standard equipment of a data terminal device such as the above-mentioned data terminal 401, for example, RS232C, Centronics, LA.
N or other communication i / f, a personal computer, or an internal bus of a workstation, such as an ISA bus or PCMC
IAi / f or the like is applicable.

The terminal control unit 407 is responsible for various communication controls necessary for data communication between the data terminal 401 and the wireless adapter 402 via the communication i / f 406.

The channel codec 408 performs frame processing and radio control. The data assembled into a frame by the channel codec 408 is transmitted to the radio unit 4.
It will be transmitted to the centralized control station and the opposite terminal via 03.

The error correction processing unit 409 is used to reduce bit errors occurring in data by wireless communication. At the time of transmission, an error correction code is inserted in the communication data. Further, at the time of reception, an error position and an error pattern are calculated by arithmetic processing, and a bit error in the received data is corrected.

The timer 410 is the wireless adapter 402.
It provides the timing signals used by each block inside. The HP storage register 411 stores the moving frequency.

The retransmission control unit 412 has an error correction processing unit 40.
When the data cannot be corrected in 9, the retransmission request frame is created and the retransmission processing is performed. The transmission counter 413 and the reception counter 414 are used to check the data transmission / reception number.

FIGS. 5 (1) to 5 (8) are explanatory views showing a radio frame configuration used in this system. Hereinafter, the internal data of the frame will be described in detail.

FIG. 5A shows the overall frame structure. In the figure, CNT is a system control channel, LCC
H is a logical control channel. In addition, two audio channels are used, one for each bidirectional communication. In addition, the data channel is the channel used for data transmission and END is the frequency switching time for the next frame. Further, in FIG. 5A, F1 and F3 are frequency channels used when wirelessly transmitting this frame, and indicate that the frequency channel is changed for each frame.

FIG. 5B shows the frame structure of the system control channel. In the figure, CS is 12.8 μs
ec minutes of carrier sense time, and R is 6.4 μm.
This is a ramp bit for sec. PR is a 56-bit preamble for capturing bit synchronization,
SYN is a 31-bit frame synchronization signal defined by one dummy bit + RCR. Further, the ID is RCR
BF is a 63-bit calling signal + 1 dummy bit defined by the following equation, and BF is 8-bit basic frame number information (1
~ 20 cycles). The MF is 8-bit multiframe number information (cycles 1 to 16), and the WA is a field for entering a system address of a terminal to be activated among terminals in the sleep mode.
Further, Rev is an area number for distinguishing from an adjacent cell, and GT represents a guard time. This channel is transmitted from the central control station for synchronizing the whole system and for controlling.

FIG. 5C shows the frame structure of the logical control channel. In the figure, CS0, CS1, CS2
Is a carrier sense time slot, which can be given a priority according to the purpose of use. PR is a 56-bit preamble for bit synchronization acquisition, and UW
Is a 24-bit unique word (for capturing byte synchronization).

The DA is a field for writing the system address and receives the same address as its own. DATA is a data slot accommodating logical control data, and CRC is CRC information for data up to the data portion of BF to LCCH. Furthermore, CF
Represents a guard time for frequency switching. The logical control channel is transmitted at the same frequency as the frame synchronization signal channel, and is used when each terminal sets up a call or the like.

FIG. 5 (4) shows the frame structure of the data channel. In the figure, CF is a guard time for frequency switching, and CS0, CS1 and CS2 are carrier sense time slots, which can be prioritized according to the purpose of use.

PR is a 56-bit preamble for capturing bit synchronization, and UW is a 24-bit unique word (for capturing byte synchronization). The DA receives the same address as its own in the field for entering the system address. When call setup is completed and HP (for example, shift code 6) is assigned by the central control station,
The frequency is changed to HP allocated only during this frame (F7 for F1) and data is transmitted.

FIG. 5 (5) shows a data frame structure. In the figure, CMD is an ID indicating that this frame is for data transmission, and NUM is a packet number. LNG is a valid data length, and FLG is a flag indicating whether retransmission is possible.

FIG. 5 (6) shows the frame structure of the retransmission request. In the figure, CMD is an ID indicating that this frame is a retransmission request, and NUM is a packet number of data for which a retransmission request is made.

FIG. 5 (7) shows the frame structure of the voice channel. In the figure, CS is a carrier sense time of 12.8 μsec and PR is a 56-bit preamble for bit synchronization acquisition. Also UW
Is a 24-bit unique word (for capturing byte synchronization), and T / R is B channel information of 32 kbps. Further, CRC is CRC information for data, and GT represents guard time.

When communicating voice data, another HP (for example, shift code 12) is received from the central control station,
The frequency is changed to HP allocated only during this frame (F13 for F1), and the voice data is transmitted.

FIG. 5 (8) shows the frame structure of END. CF represents a guard time for frequency switching.

FIG. 6 is an explanatory diagram showing the concept of frequency hopping used in this system.

In the system of this embodiment, 1M using the 26 MHz band which is approved for use in Japan.
26 frequency channels wide in Hz are used. Considering the case where there is a frequency that cannot be used due to interference noise or the like, 10 frequency channels are selected from the 26 channels, and frequency hopping is performed on the selected frequency channels in a predetermined order.

In this system, one frame is 10 ms
The frequency channel is hopped every frame. Therefore 1 of 1 hopping pattern
The length of the cycle is 100 ms.

In the figure, different hopping patterns are shown as different patterns. As described above, by using a pattern in which the same frequency is not used at the same time in each frame, it is possible to prevent a data error or the like from occurring.

Further, when accommodating a plurality of connecting devices, a different hopping pattern is used for each connecting device in order to prevent interference between the connecting devices. With this method, a system having a multi-cell configuration can be realized and a wide service area can be obtained.

As described above, in the present system, a frame is assembled for communication between the centralized control station and the wireless telephone or data terminal and between terminals, and control is performed to switch the frequency to be used at regular time intervals. It is carried out.

The specific operation of this system will be described below in some cases. (1) Start-up operation procedure In this system, before using a voice or data channel, a logical control channel (LCCH) time-division multiplexed in a frame is used to determine a hopping pattern to be used. Is a feature.

FIG. 7 is an explanatory diagram showing the start-up sequence of the wireless communication terminal in this embodiment, and FIG. 8 is a flowchart showing the initialization operation of the wireless communication terminal in this embodiment.

In this system, the control data CNT (1001) is always transmitted from the centralized control station at a certain HP.

First, when the power of the wireless communication terminal is turned on (S
1101), stand by at an arbitrary frequency (S1102), and receive CNT (1001) at that frequency. First C
When NT (1001) is received (S1103), the frequency information of the next frame contained therein is fetched (S1103).
1104), register the frequency of the next frame (31
5) (S1105), frequency hopping is started thereafter, and reception of the next frequency is awaited (S1106).

In this way, when all the frequencies to be moved are stored in the register (315) (S1107), the initialization is finished and the communication is started (S1108). In this way, the wireless communication terminal can efficiently receive and store the HP for system control. (2) Processing at the time of transmission between wireless communication terminals FIG. 9 is an explanatory diagram showing a data communication sequence in this embodiment, and FIG. 10 shows an operation of the wireless terminal at the time of connection in the data communication of this embodiment. It is a flowchart. FIG. 11 is a flowchart showing the data transmission operation of the communication terminal in this embodiment, and FIG.
7 is a flowchart showing a data receiving operation of the communication terminal in the present embodiment. FIG. 13 is a flowchart showing the operation of the wireless terminal at the time of disconnection in the data communication of this embodiment.

When a transmitting operation is performed in the transmitting terminal station of the wireless terminal (S1301), an HP acquisition request 1201 is transmitted to the centralized control station 101 (S1302). When the HP notification 1202 comes from the central control station 101 (S1303),
A connection request 1203 is transmitted to the called terminal station, and the HP used in communication is notified (S1304). When the connection confirmation 1204 is received from the receiving terminal station (S1305), a connection completion (1205) is transmitted to the central control station 101, and the call connection is terminated (S1306).

When the call connection is completed, data communication is performed. In this embodiment, data transmission from a transmitting terminal station will be described.

When the communication is started, the transmitting terminal station first resets the transmission counter 413 to 0 (S1401).
Then, it is checked whether there is a retransmission request from the wireless side (S140
2) If not, then it is checked whether or not there is a data transmission request from the terminal (S1407). If there is a transmission request, the requested data number is put into the transmission counter 413 (S1
408). Then, the data number of the requested data is put in the packet number of the data frame (S1409), and it is checked whether the requested data is transmittable data (S14).
11). If it can be retransmitted, the retransmission flag of the data frame is turned ON (S1412), and the data 1206 of the number stored in the transmission counter 413 is transmitted (S1413).

If retransmission is impossible, the retransmission flag is turned off.
(S1414), after transmitting the data 1206 of the number stored in the transmission counter 413 (S1415), the transmitted data is deleted from the buffer (S1416). When the retransmission request 1207 is received, the number of the retransmitted data is designated (S1403), and the data of the designated number is transmitted (S1404).

When the designated data number is smaller than the transmission counter data (S1405), the next designated data is designated (S1406), and the designated data is transmitted (S1404). When the number of the designated data matches the number of the transmission counter (S1406), the normal transmission state is restored. When a disconnection request is received from the terminal (S1410),
End transmission.

When the communication is started, the receiving terminal station first resets the reception counter to 0 (S1501). When the data is received (S1502), it is checked whether the data is corrupted (S1503). If the data is not broken, the data number is next checked (S1504), and it is checked whether the data number is the number next to the reception counter number (S1505).

If the data is received in the correct order,
The data is sent to the terminal (S1506), and the data number is entered in the reception counter (S1507). If data cannot be received in order due to data corruption or missing data, the retransmission flag of the received data frame is checked (S1508), and if it is ON, a retransmission request 1207 is transmitted (S1509). If it is OFF, the data is discarded (S1510), and the data number is put in the reception counter (S1507).

When a disconnection request is received from the wireless side (S
1509) and the reception is ended.

When the disconnection request is received from the terminal and the disconnection phase is entered (S1601), the originating terminal station transmits a line disconnection notice 1208 to the receiving terminal station (S1602), and when a line disconnection confirmation 1209 comes (S1603). ), HP release 121 in order to release the HP used for the central control station
0 is transmitted (S1604). When the HP release confirmation 1211 comes, the disconnection ends (S1605).

As described above, it is possible to switch between the case where data is retransmitted and the case where it is not retransmitted, and it is possible to specify whether or not data can be retransmitted for each data packet within one communication.

In the above embodiment, the retransmission request is made using the data part of the data channel frame, but it may be made using the line control channel.

In this case, since the data channel frame is not used for the retransmission request, data can be transmitted efficiently.

Further, in the above embodiment, the data is transmitted from the transmitting terminal station to the receiving terminal station, but this is also possible in bidirectional communication. In this case, the transmission control is performed using the carrier sense time slot, and the person sending the data outputs the carrier in the time slot to indicate the intention of data transmission.

[0080]

【The invention's effect】

(1) As described above, according to the present invention, when the communication terminal communicates data, the data is left in the buffer for a certain period of time even after the transmitting communication terminal finishes transmitting the transmission data. , When the receiving communication terminal does not receive the data correctly, it sends a resend request to the transmitting communication terminal, and when the receiving communication terminal receives this, it retransmits the corresponding data to ensure the correct data. There is an effect that it can be transmitted and the error rate can be lowered.

(2) Further, the transmission side communication terminal adds a header as control data to the transmission data frame and attaches a flag in the header as to whether or not retransmission is possible. When data with a flag of possible is received, it is possible to tell the receiving terminal whether or not the data can be retransmitted by not issuing a resend request even if the data was not received correctly. There is an effect that the retransmission communication can be controlled.

(3) Also, the communication terminal on the transmitting side transmits the data to be retransmitted within one communication by switching the flag indicating whether or not the data can be retransmitted within one communication and transmitting the data. It is possible to simultaneously perform the communication for transmitting new data.

(4) Further, when transmitting data that cannot be retransmitted, the transmitting communication terminal can efficiently use the buffer memory by deleting the transmission data from the buffer immediately after the transmission. The effect is that you can do it.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a system assumed in an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a central control station of the embodiment.

FIG. 3 is a block diagram showing the configuration of the wireless telephone of the above embodiment.

FIG. 4 is a block diagram showing an internal configuration of a wireless adapter connected to the data terminal of the above embodiment.

FIG. 5 is an explanatory diagram showing a radio frame configuration used in the system of the embodiment.

FIG. 6 is an explanatory diagram showing the concept of frequency hopping used in the system of the above embodiment.

FIG. 7 is an explanatory diagram showing a start-up sequence of the wireless communication terminal of the above embodiment.

FIG. 8 is a flowchart showing an initialization operation of the wireless communication terminal of the above embodiment.

FIG. 9 is an explanatory diagram showing a data communication sequence in the above embodiment.

FIG. 10 is a flowchart showing an operation of the wireless terminal at the time of connection in the data communication of the above embodiment.

FIG. 11 is a flowchart showing a data transmission operation of the communication terminal of the above embodiment.

FIG. 12 is a flowchart showing a data receiving operation of the communication terminal of the above embodiment.

FIG. 13 is a flowchart showing an operation of the wireless terminal when disconnecting in the data communication of the above embodiment.

[Explanation of symbols]

 101: Central control station, 102-A, 102-B: Wireless telephone, 103-A: Computer, 103-B: Printer, 103-C: Copy machine, 103-D: Video conference terminal, 103-E: Facsimile 103-F: LAN bridge.

Claims (4)

[Claims] 1. A centralized control station that comprises spread spectrum wireless communication means using a frequency hopping method, sets up a call when terminals in the system perform communication, and means that performs SS wireless communication with the centralized control station. In a wireless communication system including a communication terminal, when the communication terminal communicates data, the data is left in a buffer for a certain period of time even after the transmitting communication terminal finishes transmitting the transmission data. Means, a means for requesting a retransmission to the transmitting communication terminal when the receiving communication terminal cannot correctly receive the data, and a means for retransmitting the corresponding data when the transmitting communication terminal receives the retransmission request And a wireless communication system. 2. The wireless communication system according to claim 1, wherein the communication terminal adds a header as control data to a transmission data frame, and attaches a flag indicating whether or not retransmission is possible in the header. A wireless communication system comprising: a means for receiving, when the receiving side communication terminal receives data with a non-retransmittable flag, a means for not issuing a retransmission request even if the data is not correctly received. 3. The wireless communication system according to claim 2, wherein the communication terminal has means for switching and transmitting a flag indicating whether data can be retransmitted even within one communication. Wireless communication system. 4. The wireless communication system according to claim 3, wherein the transmitting-side communication terminal has means for erasing the transmission data from the buffer immediately after the transmission when the non-retransmittable data is transmitted. A wireless communication system.