Method and system for determining contention window in adaptive back-off algorithm
A technology of backoff algorithm and determination method, applied in the field of telecommunications, can solve the problems of influence, not suitable for changing channels in real time, and cannot effectively reflect the channel state, so as to reduce unfairness, reduce system delay, and increase throughput amount of effect
Inactive Publication Date: 2012-10-03
SHENZHEN UNIV
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[0014] The implementation of the HBAB algorithm is relatively simple, and the historical channel state is considered; however, its parameter α is allocated based on empirical values, so it cannot effectively reflect the actual channel state, and is not suitable for channels that change rapidly in real time.
[0015] In short, some traditional back-off algorithms need to dynamically adjust CW according to the estimated number of nodes. The CW obtained by such algorithms can effectively reflect the theoretical environment, but calculating the estimated number of nodes requires a lot of calculations. At the same time, if the estimation is wrong, it may affect the entire algorithm have adverse effects on
Some algorithms simply consider changing CW through linear or multiplicative rules, such as BEB and HBAB above, whose CW is simply multiplied by 2 or initialized to CW min Compared with BEB, the improvement of HBAB is that it can change CW according to the historical channel state, but its change factor α is directly assigned according to the empirical value. These two algorithms are relatively easy to implement, but they cannot effectively reflect the real-time channel environment.
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[0054] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.
[0055] The present invention obtains the optimal value of α by considering adding a new variable channel utilization rate, dynamically adjusts the α value according to the proportion of conflicts that occurred during back-off in the past, and finally realizes the dynamic adjustment of the contention window.
[0056] figure 1 The implementation flow of the method for determining the contention window in the adaptive backoff algorithm provided by the present invention is shown, and the details are as follows.
[0057] In step A, the system is initialized, and the value of the contention win...
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The invention is applied to the technical field of electrical communication, and provides a method and a system for determining a contention window (CW) in an adaptive back-off algorithm. The method comprises the following steps of: (A), initializing the system, and initializing the value of the CW into a system default value CWmin; (B), recording a channel state, and updating the value of the CW on the basis of the system default value in the step A in combination with a historical channel state; (C), acquiring a back-off time slot by using the updated value of the CW, acquiring a channel utilization rate in the back-off time slot, and further acquiring a transmission probability according to the channel utilization rate; and (D), acquiring a CW change factor, and determining the CW according to the CW change factor and the transmission probability. According to the method and the system, an optimization value of the CW change factor is acquired by adding the channel utilization rate serving as a new variable, and is dynamically regulated by the proportion of conflicts which occur during previous back-off, so that the acquired change factor is variable, and the CW is dynamically regulated.
Description
technical field [0001] The invention belongs to the technical field of electrical communication, and in particular relates to a method and system for determining a contention window in an adaptive backoff algorithm. Background technique [0002] In the past few decades, with the development of wireless terminal technology, distributed networks are experiencing a stage of rapid development, such as wireless local area networks (Wireless LANs), wireless ad hoc networks and wireless mesh networks. mesh networks). Among these networks, due to their advantages of mobility, low cost, flexibility, etc., distributed networks have been rapidly popularized and promoted, gradually industrialized, and entered into daily life. [0003] In a wireless distributed network, the MAC (Medium access control) protocol is mainly responsible for the scheduling of wireless nodes and the transmission and reception of data, and the most widely used MAC protocol is IEEE 802.11. The IEEE 802.11 MAC p...
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Inventor谢宁吴军王晖
OwnerSHENZHEN UNIV