CN103856981B - Method for dynamically utilizing data packet aggregation transmission based on network state - Google Patents

Abstract

The invention discloses a method for dynamically utilizing data packet aggregation transmission based on a network state, for mainly solving the problem that the performance of a network is degraded when data packet aggregation transmission is used under the condition that the network is not in a good state in the prior art. According to the scheme, the method comprises the following steps: firstly, counting the collision occurrence rate p of the network within present time through a wireless access point AP, setting a collision occurrence rate threshold th, subsequently comparing the collision occurrence rate p with the collision occurrence rate threshold, if p is greater than th, transmitting a single data packet at a wireless station and the wireless access point AP, and if p is less than or equal to th, packaging a plurality of data packets handed down from an upper computer into one medium access control (MAC) frames for transmitting through the wireless station and the wireless access point AP. By adopting the method, the data transmission time delay of the network is reduced, the performance of the network is improved, and the method can be applied to heavy-load network communication.

Description

A Method of Dynamically Using Packet Aggregation Transmission Based on Network State

technical field

The invention belongs to the field of communication technology, and further relates to a method for dynamically using data packet transmission based on network status in the field of wireless local area networks, which can be used in wireless local area networks using data packet aggregation technology to reduce link transmission time and effectively improve the performance of wireless networks. performance.

Background technique

In a data packet communication network based on the Open Systems Interconnection OSI, each layer must add a header to the data to store some control information. The overhead caused by these header transmissions will have a great impact on network performance, especially under heavy load conditions, these overheads will reduce the bandwidth utilization of application services. For services with small data packets, header transmission takes more time, wasting most of the transmission time. In order to reduce the transmission time overhead of the header, multiple MAC frames for medium access control can be aggregated to use the same physical layer PHY header, or even the same MAC header for medium access control, effectively improving bandwidth utilization. This is the so-called data packet aggregation technology. By using this method, the additional information in each transmission frame can be reduced, and the number of frames and idle time can also be reduced, thereby reducing protocol load and improving network throughput.

B.Bellalta and M.Oliver: On the Performance of Packet Aggregation in IEEE 802.11ac MU-MIMO WLANs, IEEE Communications Letters, 2012, vol.16, no.10, pp.1588-1591 proposed that the destination address is the same when the number of stations is large The probability of will be very small, so that the data packet aggregation technology cannot be fully utilized, which can be solved by increasing the length of the queue. However, the increase of the queue length will increase the probability of scheduling a large number of data packets in one transmission, that is, high system throughput is exchanged at the cost of large delay. This algorithm does not consider that when the channel state is not good, if the aggregated data packet fails to be transmitted, it will take a long time to process and retransmit the data packet. In the wireless network, the mechanism for confirming the success of data transmission is to receive the confirmation frame ACK from the receiver within the specified time. However, the transmission time of the aggregated data packet is longer, so the corresponding waiting time for confirmation is longer than that of a single data packet. In this way, it takes a long time to confirm that the transmission of the aggregated data frame fails, and it takes a long time to retransmit. Therefore, it takes a long time to process collisions and retransmit when the packet aggregation technology is used when the network status is not good, resulting in an increase in the delay of the entire network and a decrease in network performance.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, and propose a method for dynamically controlling data packet aggregation based on network status, so as to reduce network delay and improve network performance.

To achieve the above object, technical solutions of the present invention include:

(1) The wireless access point AP sends data to the wireless station, that is, downlink data transmission:

1a) The wireless access point AP sets the network collision incidence threshold value th, and records the ratio between the number of collisions in the channel and the number of data transmissions initiated in the current time period, that is, the collision incidence rate p;

1b) The wireless access point AP obtains the channel through competition, and compares the recorded collision occurrence rate p in the current time period with the set collision occurrence rate threshold value th. If p>th, the wireless access point AP directly sends a single Data packets; if p≤th, the wireless access point AP aggregates the data packets and sends them;

(2) The wireless station sends data to the wireless access point AP, that is, the uplink data transmission:

2a) After the wireless station in the network obtains the channel through competition, it sends a request to send frame RTS to the wireless access point AP to reserve the channel;

2b) After the wireless access point AP receives the request to send frame RTS from the wireless station, it generates a confirmation transmission frame CTS, and modifies the frame format of the confirmation transmission frame CTS, that is, adds an aggregation flag bit;

2c) The wireless access point AP compares the recorded collision incidence rate p in the current time period with the collision occurrence rate threshold value th, and if p>th, the wireless access point AP will confirm the aggregation flag in the transmission frame CTS Set to 0, if p≤th, the wireless access point AP will set the aggregation flag in the confirmation transmission frame CTS to 1, and then send the confirmation transmission frame CTS to the wireless station to confirm that the channel reservation is successful;

2d) The wireless station checks the received confirmation transmission frame CTS: if the aggregation flag bit in the transmission frame CTS is confirmed to be 0, the wireless station sends a single data packet to the wireless access point AP; if the aggregation flag bit in the transmission frame CTS is confirmed If the flag bit is 1, the wireless station aggregates the data packets and sends them to the wireless access point AP.

Compared with the prior art, the present invention has the following advantages:

The present invention dynamically uses data packet aggregation transmission according to the network state, that is, data packet aggregation transmission is performed when the network state is good, and a single data packet is transmitted when the network state is not good, so as to reduce the probability of data packet transmission failure, In turn, the delay of the entire network is reduced, and the performance of the wireless network is improved.

Description of drawings

Fig. 1 is the general flowchart of the present invention;

Fig. 2 is a subflow chart of downlink data transmission in the present invention;

Fig. 3 is a sub-flow chart of uplink data transmission in the present invention.

detailed description

With reference to Fig. 1, the realization steps of the present invention are as follows:

Step 1, channel competition.

The wireless access point AP competes with the wireless station for the channel. If the wireless access point AP obtains the channel, perform step 2. If the wireless station obtains the channel, perform step 3. If neither the wireless access point AP nor the wireless station obtains the channel, That is, if a collision occurs in the channel, go to step 4.

Step 2, the wireless access point AP sends data to the wireless station, that is, performs downlink data transmission.

Referring to Figure 2, the specific implementation of this step is as follows:

2a) The wireless access point AP counts the number n of collisions and the number m of initiated data transmissions in the current time period, and calculates the ratio of the number of collisions to the number of data packet transmissions, that is, the collision occurrence rate p;

2b) The wireless access point AP sets the network collision occurrence rate threshold value th:

The setting of the threshold value th of the network collision incidence rate in the prior art is usually to set the collision incidence rate on the channel in the current time period when the actual network traffic is light as the collision occurrence rate threshold value th;

2c) Compare the collision occurrence rate p with the collision occurrence rate threshold value th in the current time:

If p≤th, that is, the channel condition is good, the wireless access point AP aggregates the data packets, that is, encapsulates the data packets delivered by multiple upper layers into a medium access control MAC frame, and sends it to the wireless station.

If p>th, that is, the channel condition is not good, then the wireless access point AP sends a single data packet to the wireless station, and after the data is sent, go to step 4.

Step 3, the wireless station sends data to the wireless access point AP, that is, performs uplink data transmission.

Referring to Figure 3, the specific implementation of this step is as follows:

3a) The wireless station initiates channel reservation, that is, after the wireless station in the network obtains the channel through competition, it sends a request to send frame RTS to the wireless access point AP to reserve the channel;

3b) The wireless access point AP sets the confirmation transmission frame CTS and sends it to the wireless station:

After the wireless access point AP receives the request to send frame RTS from the wireless station, it generates a confirmation transmission frame CTS, and modifies the frame format of the confirmation transmission frame CTS, that is, adds an aggregation flag bit;

The wireless access point AP compares the recorded collision incidence rate p in the current time period with the collision incidence threshold value th:

If p>th, that is, the network condition is not good, the wireless access point AP will set the aggregation flag bit in the confirmation transmission frame CTS to 0,

If p≤th, that is, the network status is good, the wireless access point AP sets the aggregation flag bit in the confirmation transmission frame CTS to 1, and then sends the confirmation transmission frame CTS to the wireless station to confirm that the channel reservation is successful;

3c) The wireless station sends data to the wireless access point according to the confirmation transmission frame CTS:

The wireless station checks the received confirmation transmission frame CTS: if the aggregation flag bit in the transmission frame CTS is confirmed to be 0, the wireless station sends a single data packet to the wireless access point AP; if the aggregation flag bit in the transmission frame CTS is confirmed If it is 1, the wireless station aggregates the data packets delivered by the upper layer, that is, encapsulates multiple data packets delivered by the upper layer into the same medium access control MAC frame, and sends it to the wireless access point AP, and performs step 4.

Step 4, continue to compete for the channel.

The wireless station and the wireless access point AP perform backoff, and after the backoff is completed, return to step 1 to continue competing for the channel.

The above description is only a specific example of the present invention, and does not constitute any limitation to the present invention. Obviously, for those skilled in the art, after understanding the content and principle of the present invention, it is possible without departing from the principle and structure of the present invention. In some cases, various modifications and changes in form and details are made, but these modifications and changes based on the idea of the present invention are still within the protection scope of the claims of the present invention.

Claims (2)

1. a kind of method for using packet aggregation transfer based on network state dynamic, comprises the steps：

（1）Wireless access point AP sends data to wireless site, i.e. downlink data transmission：

1a）Wireless access point AP arranges network collision incidence rate threshold value th, and records in current slot and touched in channel Ratio between the number of times for hitting and the number of times for initiating data transfer, that is, collide incidence rate p；

1b）Wireless access point AP obtains channel by competition, incidence rate p will be collided in the current slot of record with touching for arranging Hit incidence rate threshold value th to be compared, if p>Th, then wireless access point AP directly transmit single packet；If p≤th, nothing Line access point AP will be sent after data packet aggregation；

（2）Wireless site sends data to wireless access point AP, i.e. transmitting uplink data：

2a）Wireless site in network is obtained after channel by competition, and to wireless access point AP request to send frame RTS is sent, with Reserve channel；

2b）Wireless access point AP is received after request to send frame RTS of wireless site, produces a confirmation transmission frame CTS, And change the frame format for confirming transmission frame CTS, that is, increase a polymerization flag bit；

2c）Wireless access point AP will be collided incidence rate p and be compared with collision incidence rate threshold value th in the current slot of record Compared with if p>Th, then wireless access point AP will confirm that the polymerization flag bit in transmission frame CTS is set to 0, if p≤th, wirelessly connect Access point AP will confirm that the polymerization flag bit in transmission frame CTS is set to 1, then confirmation transmission frame CTS is sent to into wireless site, Acknowledgement channel is preengage successfully；

2d）Wireless site is checked to the confirmation transmission frame CTS for receiving：If confirming the polymerization flag bit in transmission frame CTS For 0, then wireless site sends single packet to wireless access point AP；If confirming, the polymerization flag bit in transmission frame CTS is 1, Then wireless site will be sent to wireless access point AP after data packet aggregation.

2. method according to claim 1, wherein step 1b）In data packet aggregation, be to pay on upper strata Multiple packets, in being encapsulated into same Media access contorl mac frame, i.e., using same Media access contorl mac frame head.