CN-116367221-B - Accurate congestion feedback mechanism and feedback device for wireless local area network

CN116367221BCN 116367221 BCN116367221 BCN 116367221BCN-116367221-B

Abstract

The invention discloses an accurate congestion feedback mechanism and a feedback device for a wireless local area network, wherein the feedback device comprises a data packet processor, an AP-ACK generator, a Count-MIN SKETCH storage structure and 4 parts of an acknowledgement packet processor. The invention is based on the segmented connection scheme, and the AP-ACK is arranged on the AP to feed back the state information of the wired link, so that the adverse effect of the wireless network environment on the congestion control of the transmitting end is avoided. The simulation platform test result shows that the invention can well solve the problem of poor transmission performance in the wireless environment caused by misjudgment congestion of the traditional TCP congestion control mechanism, effectively improve the bandwidth utilization rate and throughput and simultaneously ensure different data streams to share the channel fairly.

Inventors

SHAN DANFENG
ZHENG DINGFANG
LIANG ZEYU

Assignees

西安交通大学

Dates

Publication Date: 20260508
Application Date: 20230316

Claims (8)

1. An accurate congestion feedback mechanism for a wireless local area network, comprising the steps of: Step 1, a transmitting end generates a data packet; Step 2, the data packet arrives at the wireless access point AP, the data flow cache occupation amount is updated, the dynamic threshold value is updated, the data flow cache occupation amount and the dynamic threshold value are used for calculating a receiving window value, then the AP-ACK is generated according to the data packet information and the receiving window value and sent to a transmitting end, the congestion state information of a wire link part and the available cache size of the data flow on the wireless access point AP are fed back, then the data packet is dequeued from the cache and is transmitted to a wireless receiving end after leaving the wireless access point AP, the data flow cache occupation amount is updated, the dynamic threshold value is updated, a new receiving window value is calculated, and the AP-ACK is generated and sent to the transmitting end; step 3, after the wireless receiving end receives the data packet, returning an acknowledgement packet ACK to the transmitting end; Step 4, when the sending end receives the AP-ACK with the wired link state information, congestion control is carried out according to the wired link time delay information fed back by the AP-ACK and the data packet transmission rate, wherein the wired link time delay information is obtained by calculating the AP-ACK time stamp information; Step 5, when the sending end receives the ACK from the receiving end, the sending end confirms according to the information fed back by the ACK And step 5, for the ACK from the receiving end, if the ACK is normal, the successful reception of the data packet is confirmed according to the packet header information of the ACK, the sliding window of the receiving end is moved, if the ACK is the ACK reporting the data packet loss, the data packet loss position is judged through the mark in the sending buffer, if the ACK is the wire link packet loss, the congestion is indicated, the congestion window is reduced, the sending speed is slowed down to relieve the congestion, if the ACK is the wireless link packet loss, the congestion does not occur in the link, and only the data packet is retransmitted, so that the rapid data transmission is ensured.
2. The accurate congestion feedback mechanism for a wireless lan according to claim 1, wherein in step 2, updating the data flow buffer occupancy comprises the steps of: a1, after the data packet is stored in the queue, five-tuple information and the load size of the data packet are obtained Increasing the occupied amount of the current data stream buffer ; A2, after the data packet dequeue is transmitted to the wireless receiving end, five-tuple information and the load size of the data packet are obtained, and the buffer occupancy of the current data stream is reduced 。
3. The accurate congestion feedback mechanism for a wireless lan according to claim 1, wherein in step 2, updating the dynamic threshold comprises the steps of: acquiring the total buffer size of the wireless access point AP, and judging whether the total buffer size of the wireless access point AP is 0: if the buffer is 0, the dynamic threshold is set to be 32 A target queue length; Otherwise, calculating the total target queue length according to the number of the data streams: If the total target queue length is greater than the buffer memory, a dynamic threshold is set to 0.5 (Difference between total target queue length and cache); Otherwise, the dynamic threshold is set to 0.
4. The accurate congestion feedback mechanism for a wireless lan according to claim 1, wherein in step 2, AP-ACK is generated according to the packet information and the receiving window value and sent to the transmitting end, and the congestion status information of the wired link is fed back, which includes the following steps: Step B1, data packets are enqueued, the data stream buffer occupancy corresponding to the data packets is obtained, the data stream buffer occupancy is compared with a dynamic threshold, if the data stream buffer occupancy is greater than or equal to the dynamic threshold, an AP-ACK with a receiving window of 0 is sent to a sending end, the sending end is informed that the data stream buffer is full, and the sending rate is slowed down; step B2, updating the occupied amount of the data stream cache and updating the dynamic threshold; step B3, if the step B1 does not call the AP-ACK generator, calling the AP-ACK generator to generate AP-ACK feedback wired link congestion information; And B4, after the data packet is dequeued from the AP cache, updating the data stream cache occupation amount, updating the dynamic threshold value, calculating the available cache size of the data stream according to the data stream cache occupation amount and the dynamic threshold value, and if the corresponding data stream is marked as a zero window data stream and the available cache size of the data stream is larger than 0, calling an AP-ACK generator to generate AP-ACK and transmitting the AP-ACK to a transmitting end, feeding back that the available cache exists in the data stream on the AP, and adjusting the transmitting speed of the transmitting end.
5. The accurate congestion feedback mechanism for a wireless lan according to claim 4, wherein the AP-ACK generator generates an AP-ACK and sends the AP-ACK to the sender, comprising the steps of: step B3.1, obtaining parameters required for generating a confirmation packet according to the packet head information of the data packet; step B3.2, subtracting the data stream buffer occupation amount from the dynamic threshold value to obtain a receiving window value, and marking the data stream as a zero window data stream if the receiving window value is 0; And B3.3, generating the AP-ACK according to the parameters obtained in the steps B3.1 and B3.2 and sending the AP-ACK to a sending end.
6. The accurate congestion feedback mechanism for wireless lan according to claim 5, wherein in step B3.3, the IP header required for AP-ACK is generated using the source IP address, destination IP address, protocol number information, and the TCP header required for AP-ACK is generated using the source port number, destination port number, packet sequence number, timestamp, and receive window value information to transmit the AP-ACK acknowledgement to the sender.
7. An accurate congestion feedback device facing to a wireless local area network is characterized by comprising a data packet processor, a Count-MIN SKETCH storage structure, an AP-ACK generator and an acknowledgement packet processor; the data packet processor is used for updating parameters required by the wireless Access Point (AP) and calling an AP-ACK generator when the data packet is dequeued; The Count-MIN SKETCH storage structure is used for recording the buffer occupation amount of the data stream on the wireless access point AP; the AP-ACK generator is used for feeding back the AP-ACK to the transmitting end after receiving the data packet, informing the transmitting end of the state information of the wired link and the available buffer memory of the wireless access point AP, guiding the transmitting end to confirm the packet processor to perform accurate congestion control work and controlling the transmitting speed; the acknowledgement packet processor is located at the transmitting end, performs congestion control processing on the AP-ACK from the wireless access point AP, and performs transmission acknowledgement by using the ACK from the receiving end.
8. The accurate congestion feedback mechanism for a wireless local area network of claim 7, wherein said Count-MIN SKETCH storage structure is defined by Each element in the array being present as a counter, each row of the array corresponding to a hash function, i.e. sharing And mapping the five-tuple information of the data stream to different positions of each row through the hash function for counting and storing, and maintaining the buffer occupation amount count of each data stream.

Description

Accurate congestion feedback mechanism and feedback device for wireless local area network Technical Field The invention belongs to the technical field of computer networks, and particularly relates to an accurate congestion feedback mechanism and a feedback device for a wireless local area network. Background Wireless local area networks have become the main internet access mode in the mobile computing field, and with the rise of fields such as mobile phone games, video live broadcast and the like, the demands of users for high throughput, low delay and reliability of the wireless networks are increasing. The transmission control mechanism (Transmission Control Protocol, TCP) widely used in the network realizes the end-to-end reliable transmission, but the characteristics of the wireless network cause the TCP mechanism to perform congestion judgment and control by mistake, so that the wireless network cannot obtain good performance in the wireless environment. Congestion control mechanisms in conventional TCP protocols take link packet loss or delay increase as congestion signals. In a congestion control mechanism (e.g., reno, cubic, etc.) using packet loss as congestion determination, if a transmitting end detects packet loss, it is considered that congestion occurs in the network, and congestion is alleviated by reducing the transmission rate. The random packet loss caused by non-congestion can be generated due to signal fluctuation and weakness in the wireless network, and the transmitting end uses the random packet loss as a congestion signal by mistake, so that the transmitting rate is unnecessarily reduced, the bandwidth utilization rate is reduced, and the data transmission speed is reduced. In congestion control mechanisms (such as Vegas and BBR) based on time delay or link capacity, a transmitting end judges congestion based on the round-trip transmission time delay of a data packet or according to the estimated available bandwidth or network capacity, if the time delay is increased or the estimated parameters are changed, the transmitting end considers that congestion occurs in the link and reduces the transmitting rate. And channel competition mechanism and host mobility in the wireless network cause fluctuation and unpredictable transmission delay, which affect the correct congestion judgment of the network by the transmitting end. In summary, the characteristics of the wireless network affect the congestion determination of the existing TCP transmission protocol, and the erroneous congestion determination will cause the TCP transmitting end to unnecessarily reduce the transmission rate, which adversely affects the performance of the network system. Disclosure of Invention The invention provides an accurate congestion feedback mechanism for a wireless local area network, which meets the requirements of users on high-bandwidth and low-delay wireless network services on one hand and realizes fair use of channels among different data streams on the other hand. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention provides an accurate congestion feedback mechanism for a wireless local area network based on a segmented connection scheme to generate an AP-ACK acknowledgement packet on a wireless access point AP to feed back the partial congestion state of a wired link. An accurate congestion feedback mechanism for a wireless local area network, comprising the steps of: Step 1, a transmitting end generates a data packet; Step 2, the data packet arrives at the wireless access point AP, the data flow cache occupation amount is updated, the dynamic threshold value is updated, the data flow cache occupation amount and the dynamic threshold value are used for calculating a receiving window value, then the AP-ACK is generated according to the data packet information and the receiving window value and sent to a transmitting end, the congestion state information of a wire link part and the available cache size of the data flow on the wireless access point AP are fed back, then the data packet is dequeued from the cache and is transmitted to a wireless receiving end after leaving the wireless access point AP, the data flow cache occupation amount is updated, the dynamic threshold value is updated, a new receiving window value is calculated, and the AP-ACK is generated and sent to the transmitting end; step 3, after the wireless receiving end receives the data packet, returning an acknowledgement packet ACK to the transmitting end; Step 4, when the sending end receives the AP-ACK with the wired link state information, congestion control is carried out according to the wired link time delay information fed back by the AP-ACK and the data packet transmission rate, wherein the wired link time delay information is obtained by calculating the AP-ACK time stamp information; And 5, when the sending end receives the ACK from the receiving end, confirming accor