Contention window adjusting method taking 802.11e VoIP application as orientation

Abstract

The invention discloses a contention window adjusting method taking an 802.11e VoIP application as orientation. The method includes the steps that (1) the optimal network access probability TauAPopt of a wireless AP is calculated according to an access MAC layer parameter and a VoIP coding mode; (2) the optimal value CWminAP of the size of the minimum contention window and the optimal value CWmaxAP of the size of the maximum contention window of the AP are calculated according to the TauAPopt; (3) the average collision rate favgj in the jth period at the AP is calculated, and then the network access probability TauSTA of a site STA is adjusted according to the relation of the favgj and the threshold value fopt; (4) the maximum contention window and the minimum contention window of the site are calculated by the AP according to the TauSTA; the maximum contention window and the minimum contention window of the site are broadcasted by the AP by using a periodic Beacon frame. By means of the contention window adjusting method taking the 802.11e VoIP application as orientation, the effective availability of a wireless channel can be improved, the network throughput is improved, and the VoIP capacity is improved as well.

Description

technical field [0001] The invention relates to a contention window adjustment method for 802.11e VoIP applications. Background technique [0002] With the rapid development of Voice over Internet Protocol (VoIP) technology and Wireless Local Area Network (WLAN) technology, WLAN-based VoIP has been rapidly and widely used in recent years. IEEE802.11 Distributed Coordination Function (DCF) Media Access Control (MAC) protocol has become the mainstream WLAN MAC protocol due to its simplicity and robustness. Its basic idea is Carrier Sense Multiple Access (CSMA) and Collision Avoidance ( CA). The IEEE802.11DCF protocol mainly supports the transmission of non-real-time data streams. In order to enhance support for real-time services such as VoIP, IEEE has formulated an Enhanced Distributed Channel Access mechanism (EDCA, Enhanced Distributed Channel Access). EDCA expands QoS support on the basis of the DCF mechanism, provides a mechanism for prioritizing different service flows...

AI Technical Summary

Problems solved by technology

This method is difficult to guarantee the guarantee of QoS such as delay and jitter during VoIP transmission

CW in EDCA min with CW max Static setting of , resulting in most packets in the same discrete interval [0, CW max ] to choose, which increases the probability of conflict

The increase of conflicts greatly wastes channel resources, causing the throughput to drop rapidly, and the optimal system performance cannot be achieved.

[0006] (2) The bottleneck effect of the AP limits the VoIP capacity

When the capacity of the VoIP call link increases and the system reaches saturation, the AP will overflow the stack due to the heavy load, which will affect the data transmission from the wired to the wireless direction, resulting in the loss of voice data packets and the increase of delay.

These increases in packet loss and delay affect the VoIP call process initiated by all sites, limiting the increase in system capacity

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