JPH0818544A - Data communication equipment and method therefor - Google Patents

Abstract

PURPOSE:To avoid complicated frame reception control by not sending a prescribed amount of succeeding frames till a receiver side terminal equipment receives normally all of the prescribed mount of frames sent by a transmitter terminal equipment and sending again a frame not normally received. CONSTITUTION:A radio control section 3 receiving a transmission request from a CPU 1 provides a transmission number to a transmission frame and a transmission reception section 5 sends the resulting signal and it is stored in a transmission reception buffer memory 4. Then frames of the number on request of retransmission are sent again till the receiver terminal equipment receives all of the frames normally. When the transmission is finished, the control section 3 allows a mode changeover section 6 to set the mode of the transmission reception section 5 to the reception mode to await a NAK acknowledge from the receiver terminal equipment. After the reception of a NAK acknowledge frame, a re-transmission request number in this frame is checked and when not 0, the re-transmission processing is conducted. That is, the control section 3 allows the changeover section 6 to set the mode of the transmission reception section 5 to the transmission mode and the section 5 sends a transmission frame of the re-transmission request number selected from the memory 4 via an antenna 7. Then the operation above continues till all the frames indicated by the NAK acknowledge are sent again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication device and method for exchanging data between a transmission side terminal and a reception side device.

[0002]

2. Description of the Related Art Recently, a personal computer (hereinafter referred to as a personal computer) has been used in a resource sharing environment by a local area network (hereinafter referred to as LAN) as the performance has been improved and the technology has been downsized. It is becoming more frequent.

As a connection form of this LAN, a wired LAN which is connected to each other by a cable or the like is most popular, and a typical example of the connection cable is Ethernet (registered trademark of Xerox Co.). This Ethernet has an error rate of 1
It is as low as 0 to the 12th power, and data reliability is high. However, when a LAN is formed by using a cable such as Ethernet as described above, there is a drawback that the terminal to be connected cannot be easily moved, and the cable laying work takes time and cost. In addition, when it is desired to increase the number of terminals to be connected, there is a drawback that further construction is required and it takes time and cost.

Therefore, recently, a movement to adopt a wireless LAN for forming a LAN by using radio waves as a transmission medium has been conspicuous due to an advantage that a laying work is not necessary, and the wireless LAN is a portable terminal typified by a notebook type personal computer. It has also attracted attention as a form of LAN that makes use of portability. As described above, the wireless LAN is expected to be widely used in the future, but the wireless error rate increases to about 10 −2. In the wireless LAN, the communication error recovery processing when the receiving side terminal receiving the data on the LAN cannot normally receive the data is the wired LAN.
The method of collectively performing the transport layer, which is the upper layer, is not suitable in view of the wireless error rate. As a communication error recovery processing method suitable for wireless LAN, SR-ARQ (Se
lective Repeat-Automatic
A Repeat Request method has been proposed. This SR-ARQ method will be described below. First, the transmitting terminal continuously transmits the frames with the transmission numbers by a predetermined amount in the order of numbers, and the receiving terminal receiving this frame designates to retransmit the transmission number of the frame that could not be received normally. Respond sequentially to the sender.
This is a method in which the transmitting side terminal which has received the NAK frame from the receiving side terminal retransmits the frame having the transmission number included in the NAK frame so as to interrupt the currently transmitting frame.

[0005]

However, in the method of the above-mentioned conventional example, the frame received successfully by the receiving terminal and the NAK frame make a retransmission request with the retransmission request, and the received frames are confused with each other. It has a drawback that the control for rearranging in order becomes complicated. When it was necessary to retransmit many times, the control of rearrangement became more complicated.

The present invention has been made in view of the above-mentioned conventional example, and normally operates without transmitting the next predetermined amount of frames until the receiving terminal normally receives all the predetermined amount of frames transmitted by the transmitting terminal. An object of the present invention is to provide a data communication device and method that eliminates the complexity of control in frame reception by retransmitting a frame that could not be received.

[0007]

In order to achieve the above object, the data communication apparatus of the present invention has the following configuration.
That is, a transmission number assigning unit that assigns a transmission number to a transmission frame to be transmitted to a receiving terminal, a storage unit that stores the transmission frame, and a predetermined number of the transmission frames in the order of the transmission number assigned by the transmission number assigning unit. Transmission means for transmitting to the reception side terminal, reception means for receiving a retransmission request frame or reception confirmation frame transmitted by the reception side terminal in response, and transmission of a transmission frame to be retransmitted from the retransmission request frame received by the reception means It has an identification means for identifying the number and a retransmission means for reading out the transmission frame of the transmission number identified by the identification means from the storage means and re-transmitting it, and in the retransmission means, the reception means receives the reception confirmation frame. Until the receiving means receives the reception confirmation frame, the transmitting means transmits a predetermined amount of transmission frame. And transmitting a.

[0008]

In the above structure, the transmission number assigning means assigns the transmission number to the transmission frame to be transmitted to the receiving side terminal, the storing means stores the transmission frame, and the transmitting means receives the predetermined number of transmission frames in the order of the transmission number. The reception means receives the retransmission request frame or the reception confirmation frame from the reception side terminal, the identification means identifies the transmission number of the transmission frame to be retransmitted from the received retransmission request frame, and the retransmission means identifies the identification means. The transmission frame of the transmission number identified in step 1 is read from the storage means and retransmitted, the retransmitting means repeats the retransmission until the receiving means receives the reception confirmation frame, and the transmitting means uses the reception confirmation frame by the receiving means. Since a predetermined amount of transmission frames to be transmitted next is transmitted after receiving, it is possible to eliminate the control complexity in frame reception. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of a wireless LAN communication device which is the device of this embodiment. In FIG. 1, reference numeral 1 denotes a CPU that controls the entire apparatus, and in this embodiment, mainly controls the communication protocol within LAN except the data link layer and manages communication applications. Reference numeral 2 is a large-capacity memory that stores communication data, and 3 is a wireless control unit that is responsible for all data link control in wireless communication. 4 is a transmission / reception buffer memory for temporarily storing all data packets and control packets at the data link level,
Reference numeral 5 is a transmission / reception unit that transmits and receives wireless packets, 6 is a mode switching unit that switches the operation mode of the transmission / reception unit 5 between a transmission mode and a reception mode, and 7 is a wireless antenna.

FIG. 2 is a diagram visually showing the outline of this embodiment. The outline of the operation sequence will be described below with reference to FIG. The sending terminal is operating in send mode. A transmission number is assigned to the number of serially numbered frames, which is determined in advance between transmission and reception, and continuous transmission is performed, then the reception mode is set, and a response from the receiving terminal is waited for. The receiving terminal checks the received frame and finds that frame numbers 2 and 5 could not be received, and NAK (2,5) to request retransmission.
Send the frame. The transmitting terminal receiving the NAK (2,5) frame returns to the transmitting mode and retransmits the frames of frame numbers 2 and 5. Then, the reception mode is resumed, and a response from the receiving terminal is waited for. The receiving terminal which confirms the normal reception transmits the NAK (0) frame. N of number 0
The AK frame is a reception confirmation frame indicating that all the transmission frames 1 to 6 have been normally received. NA
The transmitting terminal which has received the K (0) frame starts transmitting the next six new consecutive frames.

The detailed operation of the transmitting terminal of this embodiment having the configuration of FIG. 1 will be described below with reference to the flowchart of FIG.

After storing the transmission data in the large-capacity memory 2, the CPU 1 makes a data transmission request to the wireless controller 3 (step S1). In response to this, the wireless control unit 3 instructs the mode switching unit 6 to set the transmission / reception unit 5 in the transmission mode (step S2). Then, before the start of transmission, the transmission number is set to an initial value of 1 (step S3), and then transmission data is loaded from the large capacity memory 2 to generate a data link level frame. This frame is generated by adding information such as a transmission source address, a transmission destination address, and a frame length, and the transmission number N = 1 is also added (step S4). Then, this one frame of N = 1 is transmitted through the transmission / reception unit 5 and the antenna 7 (step S5), and at the same time, stored in the transmission / reception buffer memory 4 in preparation for a retransmission request (step S6). Then, this transmission operation is incremented by 1 until the transmission number becomes equal to the value M previously determined between the transmitting and receiving terminals (step S7) or there is no transmission data instructed to be transmitted by the CPU 1 (step S16). (Step S17) and repeat. As a result, a fixed number of frames can be continuously transmitted at high speed. When the transmission is completed, the wireless control unit 3 switches the mode switching unit 6
To set the transmission / reception unit 5 to the reception mode (step S8) and wait for the NAK response from the reception terminal (step S8).
9). After receiving the NAK response frame, the retransmission request number R included in the frame is checked (step S10).
If the retransmission request number R is not 0 (step S11), the retransmission process is performed. First, the wireless control unit 3 instructs the mode switching unit 6 to set the transmission / reception unit 5 to the transmission mode (step S
12). Then, the transmission frame of the number requested to be retransmitted is selected from the transmission / reception buffer memory 4 (step S1
3), the data is transmitted through the transmitter / receiver 5 and the antenna 7 (step S14). Then, this operation is continued until all the frames instructed by the NAK response are retransmitted (step S
15). After sending all specified frames, step S
The process returns to step 8 and waits again in the reception mode. This is to NAK again whether or not the retransmitted frame has definitely reached the receiving terminal.
This is to confirm with the response. This operation is repeated until the retransmission request number R by the NAK response becomes 0 (step S11). When an N = 0 NAK response indicating that all M frames have been received is received, the process proceeds to step S18. If all the data transmission instructed by the CPU 1 has been completed, the transmission is completed. If the data to be transmitted still remains in the large capacity memory 2,
In preparation for the retransmission request, the transmitted frames N = 1 to 8 stored in the transmission / reception buffer memory 4 are deleted (step S19). Then, the process subsequently returns to step S2 to perform the next data transmission.

As described above, according to this embodiment, the transmitting terminal assigns a transmission number to a transmission frame and transmits the transmission frame up to a predetermined transmission number or continuously until all frames have been transmitted. High speed transmission is possible. Further, since the transmission frame is stored until the reception confirmation frame from the receiving terminal is received, retransmission can be facilitated. Further, at the time of retransmission, it is only necessary to determine the transmission number of the frame to be retransmitted, so that only the frame to be transmitted can be easily transmitted.
Also, in the transmission mode, only the retransmitted frame is transmitted and the next predetermined amount of frames is not transmitted until the receiving terminal can normally receive all the predetermined amount of frames, so that the receiving terminal receives the frame that should be received without being disturbed. it can.

[0015]

As described above, according to the present invention, the complexity of control in frame reception can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a data communication apparatus that is an embodiment of the present invention.

FIG. 2 is a diagram showing an exchange of frames between transmitting and receiving terminals.

FIG. 3 is a flowchart showing a flow of a transmitting operation in the transmitting terminal.

[Explanation of symbols]

 1 CPU 2 Large-capacity memory 3 Radio control unit 4 Transmission / reception buffer memory 5 Transmission / reception unit 6 Mode switching unit 7 Radio antenna

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H04L 29/08

Claims (3)

[Claims] 1. A transmission number assigning unit for assigning a transmission number to a transmission frame to be transmitted to a receiving side terminal, a storage unit for storing the transmission frame, and a predetermined amount of the transmission numbers assigned by the transmission number assigning unit. Transmission means for transmitting a transmission frame to the reception side terminal, reception means for receiving a retransmission request frame or reception confirmation frame transmitted by the reception side terminal in response, and transmission to be retransmitted from the retransmission request frame received by the reception means It has an identification means for identifying the transmission number of the frame, and a retransmission means for reading the transmission frame of the transmission number identified by the identification means from the storage means and re-transmitting it. Is repeated until the reception means receives the reception confirmation frame, and then the transmission means transmits the predetermined amount of data to be transmitted next. Data communication apparatus and transmits the frame. 2. A data communication method for transmitting and receiving frames between a transmission side terminal and a reception side terminal, wherein the transmission side terminal assigns a transmission number to a transmission frame to be transmitted to the reception side terminal, and the transmission frame And transmitting a predetermined amount of the transmission frame in the order of the transmission number, the reception side terminal receives the transmission frame transmitted from the transmission side terminal, and the frame that cannot be normally received among the received frames. If there is, the transmission number of the frame is determined, a retransmission request frame is transmitted to the transmission side terminal to request retransmission of the transmission frame of the determined transmission number, and if all can be received normally Transmits a reception confirmation frame to the transmitting side terminal, and when the transmitting side terminal receives the retransmission request frame from the receiving side terminal, the retransmission request frame is transmitted. From the frame, identify the transmission number of the transmission frame that the reception side terminal could not receive normally, retransmit the transmission frame corresponding to that transmission number, and when the reception confirmation frame is received from the reception side terminal, transmit next A data communication method, comprising transmitting a transmission frame to be transmitted. 3. The data communication device and method according to claim 1, wherein the transmission side device and the reception side device perform data transmission using radio waves as a transmission medium.