JPH07336366A - Radio lan system - Google Patents

Abstract

PURPOSE:To provide a radio LAN system capable of an optimum guarantee corresponding to the kind of data by discriminating the kind of reception data and retransmitting the data. CONSTITUTION:When packet data from a terminal 111 are received in a LAN controller 105, the CPU 107 of a radio adapter 2 investigates the header part of a packet and confirms whether or not the received packet is real time data (UDP) or non real time data (TCP.) Then, the presence and absence of a data retransmission processing are controlled depending on whether the received packet is an UDP packet or a TCP packet. By the constitution, time is guaranteed for the real time data and error free on communication is guaranteed for the non real time data. Thus, in the case of handling the plural kinds of the data such as video images, sound and texts, etc., the optimum guarantee is performed corresponding to the kind of the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless L having a terminal for handling real-time data such as moving images and sounds and a terminal for handling non-real-time data such as text data.
The present invention relates to data retransmission processing control of an AN system.

[0002]

2. Description of the Related Art There are generally the following types of data retransmission control modes in a conventional wireless LAN system.

(1) In the wireless communication protocol, the data resending process is not performed, but the resending process is left to a higher-level protocol or a terminal application.

(2) Data retransmission processing is performed using a procedure such as HDLC, and data errors are guaranteed end-to-end wirelessly.

(3) The presence / absence of data retransmission processing is registered for each system and each connected terminal, and communication is performed. In this case, the communication between the terminal that performs the retransmission process and the terminal that does not perform the retransmission process is generally communication without the retransmission process.

[0006]

However, the above conventional example has the following problems.

(1) It is difficult to guarantee an error for non-real-time data such as text data when data retransmission processing is not performed on the wireless communication protocol.

From this fact, generally, text data and the like are guaranteed to be error-free in communication.

(2) When guaranteeing error-free communication for all data by resending processing, it is difficult to guarantee time for data that requires real-time characteristics such as moving images and voice.

(3) In the method of determining the presence / absence of data retransmission processing for each system, in the case where a real-time data system terminal and a non-real-time data system terminal coexist in the same system, either of the above (1) and (2) These problems will be applicable depending on the type of terminal.

Further, in the method of determining the presence / absence of data retransmission processing for each terminal, a terminal (multimedia terminal) capable of handling a plurality of types of data such as video / audio / text.
When the above is connected, either of the above problems (1) and (2) will be applicable depending on the data type.

It is an object of the present invention to provide a wireless LAN system which can provide optimum guarantee according to the type of data.

[0013]

According to the present invention, a wireless adapter device connected to a terminal determines a type (real time / non-real time) of data received from the terminal, and a retransmission control means for retransmitting the data. Is provided to control the presence / absence of the data retransmission processing based on the real-time data and the non-real-time data (real-time data: no retransmission processing, non-real-time data: retransmission processing).

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a wireless LAN according to an embodiment of the present invention.
It is a block diagram showing the composition of the wireless adapter device which constitutes a system.

The wireless adapter device in this embodiment is
LAN (Ethernet) compatible multimedia terminal 11
1 is connected to an antenna 101 for transmitting and receiving radio waves, and a wireless unit 102 including a modulator / demodulator.
And a bit synchronization circuit (DPL for performing bit synchronization).
L) 103, a communication controller 104 for assembling / disassembling packets and controlling communication, a LAN controller 105 for controlling communication with the terminal 111, an encoder / decoder 106 for error code, and overall control. CPU107
It has a memory 108, a timer 109, and a counter 110 for measuring the number of frame retransmissions.

FIG. 2 is an explanatory diagram showing a format of a wireless frame used in the wireless LAN system.

FIG. 3 is a flowchart showing the operation of the wireless adapter device during transmission, and FIG. 4 is a flowchart of the operation of the wireless adapter device during reception.

The operation of the wireless LAN system in this embodiment will be described below.

(1) Operation during transmission.

Initially, the wireless adapter device is in a waiting state for receiving packet data transmitted from the terminal 111 (S3).
01).

When the LAN controller 105 receives the packet data from the terminal 111, the header portion of the packet is examined to confirm whether the received packet is real-time data (UDP) or non-real-time data (TCP) (S302).

Here, the packet received in S302 is U
In the case of a DP packet, the error correction encoder / decoder 106 adds an error correction code (S303), and the communication controller 104 creates a type 2 wireless frame (S30).
4).

FIG. 2B shows the structure of the type 2 frame.

In FIG. 2B, TYPID is an identifier indicating that the frame is real-time data, DA.
Is the destination address, SA is the source address, CNT
Is an information field such as frame type (control / data) and data length.

After the frame is created in S304, the wireless unit 102
Then, the contention control is performed and the frame is transmitted (S305). Then, after this, the packet reception standby state of S301 is set.

The packet received in S302 is TC
In the case of a P packet, the error correction encoder / decoder 106 adds an error correction code (S306), and the communication controller 1
In 04, a type 1 wireless frame is created (S30
7).

FIG. 2A shows the structure of the type 1 frame.

In FIG. 2 (a), TYPID is an identifier indicating that the frame is non-real time data, D
A is the destination address, SA is the source address, and CN
T is an information field such as frame identification (control / data) and data length, and FCS is a frame check sequence such as CRC32.

After S307, +1 is added to the value of the retransmission counter 110 (S308), and this value is maximum number of retransmissions: N
Is compared with (S309).

When the counter value: K exceeds the maximum number of retransmissions: N (N <K) in S309, the packet received from the terminal 111 is deleted, and the values of the timer 109 and the counter 110 are reset (S310). After this, the packet reception standby state of S301 is set.

If the counter value: K is equal to or less than the maximum number of retransmissions: N (N ≧ K) in S309, the radio section 102 performs contention control and sends a frame (S311), starts the timer 109, and starts transmission from the destination. The system waits for a response to be received (S312).

If no response is received from the other party within a fixed time in S312 (timeout), S
Returning to 308, frame retransmission processing is performed. Also, S3
When the response is received from the other party within a fixed time in 12, it is confirmed whether the response is ACK (normal reception) or a resend request (S313).

If the response is a resend request in S313, the process returns to S308 and the frame resend process is performed.
If the response is ACK in S313, the terminal 11
The packet received from 1 is discarded, and the values of the timer 109 and the counter 110 are reset (S310). After this,
The packet reception standby state of S301 is set.

(2) Operation during reception.

Initially, the wireless adapter device is in a standby state for receiving a wireless frame (S401), and when the wireless frame is received by the wireless unit 102 by the antenna 101, the communication controller 104 confirms the frame type (Type 1).
/ Type 2) is performed (S402).

When the received frame is a type 2 frame (real time data), the communication controller 10
At 4, the frame is disassembled and UDP data is extracted.

The extracted UDP data is decoded by the error correction encoder / decoder 106 (S403) and the LAN
It is transmitted to the terminal 111 by the controller 105 (S
404).

When the received frame is a type 1 frame (non-real time data), the communication controller 1
The FCS is checked at 04 to confirm whether or not there is a data error (S405).

If the frame received in S405 has no error, an ACK (normal reception) response is transmitted to the transmitting side (S406), and the process proceeds to error correction decoding processing of TCP data (S403).

When an error is confirmed in the frame received in S405, a resend request response is transmitted to the transmitting side (S407) and the received frame is discarded (S40).
8). After this, the process shifts to the wireless frame reception waiting state of S401.

[0041]

As described above, according to the present invention,
By deciding whether or not to perform retransmission processing depending on the type of data, time is guaranteed for real-time data,
It is possible to guarantee error-free for non-real-time data, and it is possible to perform optimal guarantee according to the type of data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a wireless adapter device that constitutes a wireless LAN system according to an exemplary embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a format of a wireless frame used in the wireless LAN system.

FIG. 3 is a flowchart showing an operation of the wireless adapter device during transmission.

FIG. 4 is a flowchart showing an operation of the wireless adapter device during reception.

[Explanation of symbols]

 101 ... Antenna, 102 ... Radio part, 103 ... Bit synchronization circuit, 104 ... Communication controller, 105 ... LAN controller, 106 ... Encoder / decoder, 107 ... CPU, 108 ... Memory, 109 ... Timer, 110 ... Counter, 111 … A multimedia terminal.

Claims (2)

[Claims] 1. A wireless L configured to have a terminal for handling real-time data and a terminal for handling non-real-time data.
In the AN system, a discrimination means for discriminating whether the data received from the terminal is real-time or non-real-time and a retransmission control means for re-transmitting the data are provided, and the presence or absence of the data retransmission processing is controlled by the real-time data and the non-real-time data. A wireless LAN system characterized by: 2. The wireless LAN according to claim 1, wherein real-time data is not retransmitted and non-real-time data is retransmitted.
system.