JPH1168767A - Radio transmission equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce overheads for transmission control in a simple configuration and prevent a deadlock by starting the next state after a response to a transmitted control signal is waited and retransmitting the control signal when the response can not be received within a fixed time. SOLUTION: A transmission control part for a server side terminal detects the presence/absence of an error in a control request frame 5-1 through an error detecting means. When it is confirmed the control request frame 5-1 contains no error, a control confirmation frame 5-2 is transmitted but when that frame contains any frame, it is abandoned. A terminal side control part starts a timer when transmitting the control request frame 5-1, receives the control confirmation frame 5-2 within time-out time and transits into relevant next control state when it is confirmed the control confirmation frame 5-2 contains no error. Besides, when the control confirmation frame 5-2 can not be received within the time-out time, the control request frame 5-1 is transmitted again.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of transmitting high-quality encoded music data and image data stored in a server device connected to a LAN from a terminal device connected to a public mobile communication network such as a PHS. The present invention relates to a wireless transmission device equipped with a transmission control function between a server device and a terminal device in an information transmission system obtained by transmitting a control signal to a server device.

[0002]

2. Description of the Related Art Conventionally, when acquiring stored information at a terminal connected to a public network from a server device connected to a LAN, since TCP is used as a communication protocol on the LAN, there are many problems. In this case, TCP is often used to guarantee error-free transmission between the server device and the terminal device. Further, when a wireless communication network such as a PHS is used as a public network, transmission efficiency is extremely reduced in error-free transmission using only TCP. Therefore, as shown in FIG. In some cases, TCP is used as an upper layer protocol. However, in the case of the transmission method shown in FIG. 1, the overhead due to TCP is large. In particular, when a terminal device is connected to a server device using a wireless transmission path with a narrow transmission band, such overhead causes transmission efficiency to increase. There is a problem that lowers greatly. Therefore, as shown in FIG. 2, it is conceivable that error-free is guaranteed by TCP in the LAN section, and only the payload of the TCP packet is transmitted using the layer 2 protocol in the section of the public network. However, in this case, since there is no means for guaranteeing error-free between the terminal adapter and the TCP packet / serial converter, if an error occurs in this section due to electric noise or the like, there is no means for detecting and recovering. there were.

[0003]

SUMMARY OF THE INVENTION The present invention is a simple process for realizing information acquisition from a server device connected to a LAN to a terminal connected to a wireless communication network with as little overhead as possible on a transmission path. It is an object of the present invention to provide a wireless transmission device that can continue operation without falling into a deadlock even when an error occurs.

[0004]

A server connected to a LAN, a converter for converting between a TCP packet transmitted on the LAN and a serial line, and a terminal connected to a communication network with the converter. An information transmission system includes a terminal adapter that guarantees error-free transmission between the terminal device and a terminal adapter that guarantees error-free transmission between the terminal adapter and the terminal adapter. A means for transmitting data and a control signal in a fixed-length frame having a synchronization flag, and a control signal transmission frame having additional information for detecting frame errors;
A means for discarding a received frame when an error is detected on the receiving side, and a transition to the next state after waiting for a response to the transmitted control signal, and retransmitting the control signal when a response cannot be received within a fixed timeout period. Means,
A wireless transmission device that has a simple configuration, reduces overhead for transmission control, and does not fall into a deadlock by providing a means for searching for a fixed address in a buffer area corresponding to a fixed-length frame when pulling in frame synchronization. I will provide a.

[0005]

FIG. 3 is a block diagram of a transmission system for explaining the present invention, FIG. 4 is an embodiment of a server-side and terminal-side communication control device according to the present invention, and FIG. This is an operation example for performing the operation. FIG. 3 is an example of a transmission system including a server and terminals connected to a LAN,
3-1 is a server device, 3-2 is a coded data storage / management unit of the server, 3-3 is a terminal transmission control unit for performing transmission control for each terminal, 3-4 is a TCP control unit, and 3-5 is a TCP control unit. The payload of the TCP packet is extracted and sent to the serial line, or the data received from the serial line is
TCP / serial converter for transshipping into CP packets,
3-6 is a terminal adapter having a layer 2 control function such as HDLC, 3-7 is a mobile terminal, and 3-8 is a layer 2 control having a function capable of communicating with the layer 2 function of the server terminal adapter 3-6. 3-9, a terminal-side transmission control unit having a function of communicating with a terminal-side transmission control unit 3-3, which performs transmission control for each terminal on the server side, and 3-10, a server-side encoded data storage / management unit. This is a decoder for decoding the encoded data received from 3-2.

The present invention relates to a terminal transmission control unit 3-3 for performing transmission control for each terminal in FIG.
And a terminal-side transmission control unit 3-9 having a function of communicating with the terminal-side transmission control unit 3-9, which performs transmission control for each terminal. Communication control is performed without having an overhead for free control and without falling into a deadlock as a transmission system even when an error occurs on a transmission path.

FIG. 4 shows an embodiment of a terminal configuration according to the present invention, wherein 4-1 is a line interface having an interface for a mobile network radio, and 4-2 is a layer 2 interface.
A control unit, 4-3 is a transmission / reception buffer for a transmission frame communicating between the server-side terminal transmission control unit 3-3 and the terminal-side transmission control unit 3-9, and 4-4 is a terminal for transmitting control signals. The transmission frame generation unit 4-5 generates a transmission frame, analyzes the flag of the transmission frame, and distributes the control frame to the transmission control unit 4-7 and the encoded data to the decoder 4-8. A frame analysis unit for drawing in frame synchronization, a timer 4-6 for monitoring a timeout, etc., a command 4-7 receives an instruction from a user interface of the terminal, transmits control information and receives an acknowledgment from the server. This is a terminal control unit that performs control to transition to the next state.

FIG. 5 shows a terminal-side transmission control unit 3 according to the present invention.
9 and an example of a communication sequence between the server-side terminal transmission control unit 3-3, where 5-1 is a control request frame, 5-2 is a control confirmation frame, and 5-3 is an information frame having encoded data as a payload. It is.

Hereinafter, an operation example according to the present invention will be described with reference to FIGS. 3, 4, and 5. FIG. When the server side information to be downloaded is specified in the terminal side user interface,
The terminal control unit 4-7 executes the designated control by the frame generation unit 4
-4, the frame generation unit 4-4 generates a fixed-length control request frame 5-1 to which the control information is used as a payload and to which a frame identification flag, an error detection code such as a CRC is added, and transmits the frame to the transmission frame buffer 4-4. -3, the layer 2 control unit 4-2 adds a header for layer 2 control, etc., and transmits the data via the line interface 4-1. The server-side terminal transmission control unit 3-1 checks the presence or absence of an error in the control request frame 5-1 by error detection means such as a CRC, and when it is confirmed that the control request frame does not include an error, the control check is performed. The frame 5-2 is transmitted, and if an error is included, the frame is discarded. The terminal side control unit 4-7 transmits the timer 4 when transmitting the control request frame 5-1.
-6 is activated, the control confirmation frame is received within the timeout period, and if it is confirmed that the control confirmation frame 5-2 does not include an error, the state transits to the next control state. If the control confirmation frame 5-2 cannot be received within the timeout period, the control request frame 5-
1 is resent. Further, in the present invention, in order to reduce the control load on the terminal side, the response of the server to the control request frame 5-1 is limited to the response to the control request or the information frame 5-3 depending on the control content. Is changed only by the control request from the terminal side, and the control confirmation frame 5 transmitted from the server side to the terminal side.
Even when -2 is incorrect, the control confirmation frame 5-2 is transmitted again by receiving the control request frame 5-1. The terminal transmits a control frame requesting the transmission of the information frame 5-3 from the terminal to the server. The server receives the control frame without error, starts transmitting the information frame 5-3, and the terminal transmits these frames. Is received, the terminal-side frame analyzing unit 4-5 determines whether or not there is an information frame having a flag indicating that the frame is an information frame at the address of the transmission frame buffer 4-3 where the next received frame is written. Inspection is performed, and when the information frame is normally received, the data is passed to the decoder 4-8 to decode the encoded data. When the corresponding flag does not exist at the assumed address, it is determined that the flag is incorrect. Then, by checking whether or not there is a flag indicating the information frame at the address ahead of the information frame length (fixed length), the information frame is synchronized.

[0010]

As described above, according to the present invention, the terminal and the L
Provided is a means for reducing overhead between servers connected to an AN and enabling a system to perform communication control without falling into a deadlock even when an error occurs on a transmission path. Further, the communication control method described in the embodiment of the present invention has an effect that the communication control processing on the mobile terminal side, which is required to simplify the processing as much as possible, can be simplified.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a transmission system for explaining a conventional technique.

FIG. 2 is an explanatory diagram of a problem that occurs in a system configuration for reducing overhead for transmission control that occurs when using the related art.

FIG. 3 is a configuration diagram of a transmission system for explaining the present invention.

FIG. 4 is an embodiment of a terminal configuration according to the present invention.

FIG. 5 is an example of a communication sequence according to the present invention.

[Explanation of symbols]

3-1 Server connected to LAN 3-2 Encoding data storage management unit 3-3 Terminal transmission control unit 3-4 TCP control unit for LAN transmission control 3-5 Extracting payload of TCP packet To send the data to the serial line, or to transpose the data received from the serial line into TCP packets.
Serial conversion device 3-6 Terminal adapter having layer 2 control function such as HDLC 3-7 Mobile terminal 3-8 Layer 2 of server side terminal adapter 3-6
Layer 2 control unit having a function capable of communicating with the function 3-9 Terminal side transmission control unit having a function capable of communicating with the terminal transmission control unit 3-3 which performs transmission control for each terminal on the server side 3-10 Server side Decoder for decoding encoded data received from encoded data storage / management unit 3-2 4-1 Line interface having interface for mobile network radio 4-2 Layer 2 control unit 4-3 For server side terminal A transmission / reception buffer for a transmission frame communicated between the transmission control unit 3-3 and the terminal side transmission control unit 3-9 4-4 A transmission frame generation unit generated for transmitting control signals on the terminal side 4-5 The flag of the transmission frame is analyzed, the control frame is distributed to the transmission control unit 4-7, and the encoded data is distributed to the decoder 4-8. Frame analysis unit to be pulled in 4-6 Timer to monitor timeout etc. 4-7 Control to transition to the next state by receiving instructions from user interface of terminal, transmitting control information and receiving confirmation response from server side Terminal control unit to perform 5-1 Control request frame 5-2 Control confirmation frame 5-3 Information frame

Claims (1)

[Claims] 1. A server device connected to a LAN, comprising:
A converter for converting between a TCP packet transmitted over N and a serial line, a terminal adapter connected to the converter and a communication network including at least a wireless section, and for ensuring error-free transmission between the terminal and the terminal; In an information transmission system including a terminal device having means for ensuring error-free transmission with the terminal adapter, data and control are performed using a fixed-length frame having a frame synchronization flag between the server device and the terminal device. Means for communicating signals, at least the control signal transmission frame has additional information for frame error detection, means for discarding the received frame when an error is detected on the receiving side, and the next state after waiting for a response to the transmitted control signal. And if no response can be received within a certain timeout period, retransmit the control signal. Wireless transmission device comprising: