WiMAX system up band width dynanic distributing method

Abstract

The invention relates a dynamic allocating method of uplink bandwidth of WiMAX system, comprising: firstly analyzing the relationship between collision probability, competition service stream number and competition bandwidth size of the cutoff binary index retreating algorithm, and determining the initial size of competition request bandwidth of uplink subframe of WiMAX system; then according to the allocating result, data packet arrival condition, and bandwidth request mode of the previous frame, real-timely and dynamically regulating the competition request bandwidth, and nrtPS and BE data transmission bandwidth size of the uplink subframe; in the regulating course, able to make congestion control of the request according to the number of requests which has been received by BS end but do not obtain bandwidths and the request-allowed maximum delay time, to receive or refuse a new request. And the method can effectively reduce bandwidth request collision probability, raise system transmission efficiency, improve MAC layer performance on different flow load conditions, and to a certain extent, make network congestion control, and it is an effective and practical allocating method.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to the allocation of uplink bandwidth in a WiMAX system. Background technique [0002] The 802.16 standard mainly defines the physical layer and MAC layer of the WiMAX system in detail. The standard supports three duplex modes: time division duplex (TDD), frequency division duplex (FDD) and half frequency division duplex (HFDD). Since the TDD mode does not require symmetrical frequency bands, and the division of uplink and downlink subframes in each frame can be dynamically adjusted, it has been widely used. In addition, the standard supports two networking methods, point-to-multipoint (PMP) and mesh network (Mesh), but only the PMP method is widely used. [0003] In the WiMAX system, each user station SS shares the uplink channel bandwidth in TDMA mode through DAMA, and the SS submits a bandwidth application (except for the UGS scheduling type that is actively grant...

AI Technical Summary

Problems solved by technology

Obviously, when the SS does not need to send a bandwidth request message, this method wastes bandwidth resources; and if the allocated bandwidth corresponds to Multicast CID or Broadcast CID, it is expressed as multicast or broadcast polling. At this time, the BS allocated The uplink bandwidth is shared by multiple SSs, and multiple SSs can send requests at the same time, so it will cause competition, which may cause collisions and invalidate the requests, as shown in Figure 1

The size of the probability of magnetic collision is related to the size of the contention request bandwidth allocated by the system for sending bandwidth request messages. If the allocated contention request bandwidth is larger, the probability of collision will be smaller and the passing rate of bandwidth request messages will be greater. , but at this time the bandwidth used for unicast polling and data transmission will decrease; and if the size of the contention request bandwidth is reduced, the collision probability of the request message will increase, so the WiMAX system is in the allocation of the contention request bandwidth and There is an optimization problem in the allocation of data transmission bandwidth

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