JP2005020528A - Wireless device - Google Patents

Abstract

An object of the present invention is to provide a wireless device that more accurately transmits data requiring real-time performance.
Transmission means for wirelessly transmitting first data and second data, means for determining whether the first data has arrived at a transmission destination (S106), and the first data to the transmission destination If it is determined that the first data has not been received, first setting means (Yes in S108) is set to retransmit the first data before transmitting the second data, and the first data is transmitted to the first data. If it is determined that the data has not arrived first, second setting means (S110) for setting the first data to be retransmitted after transmitting the second data, and the first data is transmitted in real time. A wireless device comprising means (S108, S109) for switching between the first setting means and the second setting means depending on whether or not the data should be.
[Selection] Figure 5

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wireless device, and more particularly, to a wireless device that transmits data that requires real-time transfer.
[0002]
[Prior art]
There is a wireless communication technique represented by a communication method generally referred to as a wireless LAN, which uses a technique shown in IEEE (Institute of Electronics and Electronics Engineers) 802.11. Since wireless is used, it is considered that a large number of events in which a desired frame (a unit of a signal transmitted in the data link layer of an OSI (Open Systems Interconnection) reference model) does not reach the transmission destination may occur. Here, means for increasing the certainty of arrival using a retransmission technique based on a lower hierarchy has been used.
[0003]
There are various types of data that flow on the communication path, and the required communication quality varies. As a straightforward example, in a protocol in which reliability is ensured in an upper layer (for example, TCP / IP (Transmission Control Protocol / Internet Protocol)), data that does not require fast delivery such as file transfer, and streaming (Data that is played back sequentially while downloading video data on the server, etc.) is required to arrive before the desired time, and video playback is interrupted even after reaching a certain time, In some cases, the data is meaningless. If re-transmission is performed in the lower layer with the same rule between these, it becomes a transmission means that does not conform to the respective data characteristics, and it may interfere with stable streaming as well as overall throughput.
[0004]
In order to avoid this, it is necessary to transmit by a method according to the desired communication property. As a known retransmission method, in the OSI reference seven-layer model, there is means for continuously transmitting a transmission failure frame as retransmission in the physical layer. In the upper layer, there is means for rearranging the transmission failure frame after the transmission waiting queue. And it was common to determine the parameters of these by the implementer.
[0005]
As a conventional wireless data transmission method, by embedding unique information in an information frame, importance is assigned to the information frame according to the information content to be transmitted, and all information is not transmitted to the other party as a result. Even in this case, there is an efficient data transmission method that is effective as long as necessary minimum information can be transmitted to the other party according to the assigned importance (see, for example, Patent Document 1).
[0006]
[Patent Document 1]
JP 2002-374316 A (page 9, FIG. 4)
[0007]
[Problems to be solved by the invention]
However, embedding unique information in an information frame takes processing time and may cause an overall transmission time delay. In particular, when the data to be transmitted is a mixture of data that requires real-time property and data that is not so, transmission time is delayed, and there is a case where the data is not accurately delayed.
[0008]
An object of the present invention is to provide a wireless device that more accurately transmits data requiring real-time performance.
[0009]
[Means for Solving the Problems]
The first invention is a transmitting means for wirelessly transmitting the first data and the second data, a means for determining whether the first data has reached the destination, and whether the first data has reached the destination If it is determined that the first data has not been transmitted, the first setting unit configured to retransmit the first data before transmitting the second data and the first data is determined not to reach the transmission destination. Then, after transmitting the second data, the second setting means for setting the first data to be retransmitted, and whether the first data is data to be transmitted in real time, A wireless device comprising: one setting means and means for switching between the second setting means.
[0010]
According to a second aspect of the present invention, there is provided: a first designation unit that designates a maximum number of retransmissions by the first setting unit; and a second designation unit that designates the maximum number of retransmissions by the second setting unit. The wireless device according to the first invention, further comprising:
[0011]
A third invention is the radio apparatus according to the second invention, wherein each of the first and second specifying means specifies the maximum number of retransmissions to be specified depending on a communication protocol.
[0012]
According to a fourth aspect of the present invention, in each of the first and second designation means, the maximum number of retransmissions to be designated is designated depending on a destination port number of a transmission frame. Device.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a radio apparatus according to an embodiment of the present invention. The wireless device includes a wireless transmission / reception unit 120 that transmits / receives data via an antenna 110, a signal processing unit 130 that processes signal data between other wireless devices, and a communication protocol processing unit 140 that processes a wireless communication protocol. A CPU (Central Processing Unit) 150 that has an internal memory (may be external) and executes control of the entire wireless device, an input unit 160 through which a user inputs data such as a control command, And a display unit 170 that displays input data and the like. This embodiment prepares several combinations of retransmission methods according to the nature of the data to be transmitted, and uses these retransmission methods according to the data to be transmitted, thereby reducing unnecessary transmission and reducing the overall throughput. Provide improved and comfortable data transmission. The signal processing unit 130 and the communication protocol processing unit 140 execute these retransmission methods.
[0014]
FIG. 2 shows the lower four layers of the OSI (Open Systems Interconnection) reference seven-layer model of the wireless device according to the present embodiment. The physical layer 210, the data link layer 220, the network layer 230, the transport layer 240, and the upper layer Layer (session layer, presentation layer, and application layer) 250. The physical layer 210 corresponds to the wireless transmission / reception unit 120 of FIG. 1, and the data link layer 220, the network layer 230, and the transport layer 240 correspond to the signal processing unit 130 and the communication protocol processing unit 140.
[0015]
Next, two retransmission methods used in this embodiment will be described with reference to FIGS. 3 and 4. The physical layer 210 is generally realized by an integrated circuit, and retransmission can be performed in a short time (for example, μS order) (retransmission method A). However, according to the IEEE802.11 transmission rule, transmission is not always possible at a desired time, and some waiting time may occur. During this time, the wireless device is in a transmission waiting state.
[0016]
For this reason, the data link layer 220 also has a retransmission method (retransmission method B). The retransmission method here is to change the information required for retransmission and place it at the end of the queue. Compared with retransmission method A, the procedure takes time. The physical layer retransmission means tries to transmit the data continuously, and the data link layer retransmission means rearranges it behind the queue (data sequence waiting for the transmission order) for transmission opportunities. Waiting for Although retransmission method A can obtain an early retransmission opportunity, there is a side effect of stopping data (data 2 to data 5) in the subsequent queue. The retransmission method B has the property that the retransmission opportunity of the data 1 is after the data 2 to the data 5, but does not hinder the transmission of subsequent data.
[0017]
Now, considering the data that flows on the communication path, data that is generally intended to deliver information that does not differ as a result, such as file transfer, and is desired at the time of playback, such as streaming music or video There is data for the purpose of delivering data. In this embodiment, communication is performed with a difference in the condition of the maximum number of retransmissions in the retransmission method. A flowchart of the transmission procedure will be described with reference to FIG.
[0018]
First, the port number of the network / transport layer is determined on the originating side and the called side so as to be unique for each data type. When the transmission procedure is entered (S101), the network / transport layer assigns a port number to which the data belongs. As an example, a port number 21 of a general file transfer protocol is assigned for data relating to file transfer. Also, data is created by assigning port 1234 to data that is streamed as particularly characteristic data. The data link layer (MAC (Media Access Control) layer in IEEE802.11) that receives these data examines the port number (S102), determines the retransmission pattern of the frame forming the data (S103), This information is stored in the memory space belonging to the frame. Here, a table as shown in FIG. 6 is set in the data link layer, and a retransmission pattern is determined with reference to the table every time data arrives from an upper layer. Thereafter, transmission data is transferred to the physical layer (S104), and transmission is performed (S105). If the transmission is successful (S106), this is notified to the upper layer (S107), and this transmission is completed. In the case of transmission failure, retransmission is attempted up to the maximum number of retransmissions of the set retransmission method A (S108). Transmission data that has reached the maximum number of retransmissions in retransmission method A attempts to be retransmitted up to the maximum number of retransmissions in retransmission method B (S109). The retransmission here is realized by rearranging the data to the last part of the queue (S110). A frame that fails to be transmitted without being retransmitted a predetermined number of times is discarded (S111).
[0019]
For example, a series of data from data 1 to data 5 as shown in FIG. 4 is non-real-time data, and the maximum number of retransmissions in retransmission method A is 1 as shown in FIG. A description will be given of what kind of re-transmission is performed before the data 1 is discarded without being transmitted (S111) in the case where the number of times is two. First, data 1 was transmitted (first transmission) (S105), but failed (to S108). Next, data 1 (retransmission by method A) was retransmitted (Yes in S108), but failed (again, return to S108). Here, since the maximum number of retransmissions by method A is exceeded, the process proceeds to No in S108. Since the number of retransmissions by method B is 0, the data is rearranged after data 2 to data 5 in S110. Note that the number of retransmissions by method A is reset to zero.
[0020]
Then, retransmission (first time) by method B is performed (S105), but fails (to S108). The retransmission by the method A is performed once again, but it fails (to No in S108). The second retransmission of method B is performed but fails. Re-transmission by method A is performed once but failed. Then, since the number of retransmissions by method B is the third, the process proceeds to No in S109 and the data is discarded (S111).
[0021]
In the case of FIG. 6, FTP (File Transfer Protocol) data and streaming data are transmitted according to the same flowchart procedure, but a frame formed from data that has reached the data link layer (MAC layer) is filled in the transmission queue. In this case, if the port number of the arrival data is 1234, the maximum number of retransmissions for retransmission method B is set to 0, and the maximum number of transmissions for retransmission method A is set to 5. Similarly, if the port number of the arrival data is 21, since there is no corresponding port number, the maximum number of retransmissions for retransmission method B is set to 2 and the maximum number of transmissions for retransmission method A is set to 1 as other data. I decided to. As a basis for such setting, the maximum number of retransmissions of the retransmission method A is set for streaming data in which fast delivery is regarded as important, and transmission after a specified time becomes meaningless. Set the maximum number of retransmissions small (or 0). In addition, since file transfer data that does not place importance on quick delivery may be immediately followed by streaming data, the retransmission method A is set to be smaller so that the waiting time for transmission of the queue subsequent data is shortened as much as possible. In order to reduce the overhead of returning data to the upper layer, the maximum number of retransmissions in the data link layer (MAC layer) is secured to some extent. Thus, by changing the retransmission setting in real time, even when data having different properties are simultaneously transmitted on the same communication path, it can be efficiently realized. In the above example, one kind of port number and other numbers are set. However, by setting a plurality of port numbers in the table as shown in the table of FIG. 7, more detailed transmission settings can be performed. Here, first, it is divided into TCP and UDP (User Datagram Protocol), and further divided according to whether or not the data sent by UDP requires real-time property.
[0022]
(Modification) In the above example, the determination is made based on the port number, but it is also possible to perform retransmission setting with more detailed settings. As shown in FIG. 8, by setting the upper layer 250 to specify the maximum number of retransmissions to the interface of the data link layer (MAC layer) 220, it is possible to set the maximum number of retransmissions in units of data. For data that is particularly important and for which delay is desired to be reduced, a mode in which re-transmission by re-transmission method A is set to be extremely large is designated. In this case, it is not necessary to refer to the maximum retransmission number table as shown in FIGS.
[0023]
The above-described embodiment is a preferable specific example of the present invention, and thus various technically preferable limitations are attached. However, the embodiments are appropriately combined and changed within a range not departing from the gist of the present invention. It goes without saying that it can be done. For example, by connecting a wireless LAN card including the antenna 110 and the wireless transmission / reception unit 120 to a notebook computer, and installing a driver having the processing procedure described in the flowchart of FIG. It can operate as the wireless device described in this embodiment.
[0024]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a wireless device that more accurately transmits data that requires real-time performance.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a radio apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing lower four layers of an OSI (Open Systems Interconnection) reference seven-layer model of the wireless device according to the present embodiment.
FIG. 3 is a view for explaining an OSI reference model for performing retransmission according to the embodiment;
FIG. 4 is a diagram for explaining two retransmission methods according to the present embodiment.
FIG. 5 is a flowchart of a wireless device according to the present embodiment.
FIG. 6 is a diagram showing the maximum number of retransmissions for each type of transmission data according to the present embodiment.
FIG. 7 is a diagram showing the maximum number of retransmissions for each type of transmission data according to the present embodiment.
FIG. 8 is a diagram for explaining a modification of the embodiment.
[Explanation of symbols]
110 Antenna 120 Wireless Transmission / Reception Unit 130 Signal Processing Unit 140 Communication Protocol Processing Unit 150 CPU
160 Input unit 170 Display unit

Claims (4)

Transmitting means for wirelessly transmitting the first data and the second data;
Means for determining whether the first data has reached the destination;
Determining that the first data has not arrived at the destination, first setting means for setting the first data to be retransmitted before transmitting the second data;
Determining that the first data has not arrived at the destination, second setting means for setting the first data to be retransmitted after transmitting the second data;
A wireless apparatus comprising: means for switching between the first setting means and the second setting means depending on whether the first data is data to be transmitted in real time. First designation means for designating a maximum number of retransmissions by the first setting means;
The radio apparatus according to claim 1, further comprising: a second specifying unit that specifies the maximum number of retransmissions by the second setting unit. The radio apparatus according to claim 2, wherein each of the first and second designation means designates the maximum number of retransmissions to be designated depending on a communication protocol. 3. The radio apparatus according to claim 2, wherein each of the first and second designation means designates the maximum number of retransmissions to be designated depending on a destination port number of a transmission frame.

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