Research And Development Of Ultra High Throughput WLAN Cross-Layer Optimization Technology

In recent years,Wireless Local Area Networks(WLAN)has become one of the most important traffic carrying modes.The 5th Generation Communication System(5G)will be a combination of multiple wireless access technologies,including 5G New Radio(NR),Long Term Evolution(LTE),WLAN and so on,in order to achieve higher coverage,availability and network density.As the communication standard of WLAN,IEEE 802.11 effectively improves the transmission rate by introducing MIMO,spatial multiplexing and other technologies,but even the latest WLAN standard can not meet the rate requirements of 5G.Ultra high throughput WLAN,a new wireless LAN technology which combines the latest standard of IEEE 802.11 and constantly develops to 5G diversified demand,has gradually attracted wide attention in the industry because it can realize ultra high throughput wireless LAN transmission to meet the challenges of 5G larger capacity and diversified application scenarios.At present,there are still some problems to be solved urgently in ultra high throughput WLAN: on the one hand,ultra high throughput WLAN needs to meet the needs of higher transmission rate;on the other hand,inefficient MAC layer protocol has become the main factor limiting system performance,so it is necessary to improve media access control mechanism to provide higher quality of service.In view of the above requirements and problems,this paper studies the cross-layer optimization technology of ultra high throughput WLAN.The specific work and contributions are summarized as follows:Aiming at the demand of higher transmission speed of ultra high throughput WLAN,combined with the idea of IEEE 802.11 ay beamforming,this thesis designs and implements a novel cross-layer antenna control protocol by introducing beam switching technology.The beam switching technology has the characteristics of high directional gain,which can effectively improve the throughput and realize controllable space division multiple access.The cross-layer antenna control protocol is mainly composed of a beam training scheme and a beam switching scheme.The two-stage binary beam training scheme completes the mapping process between the node and the optimal beam with very low time complexity.The beam switching scheme is based on different states of the node.Complete the corresponding beam switching action.Aiming at the problem that the nodes in the beam training may be in the "fuzzy zone",a multi-antenna based solution is proposed.Finally,this paper implements the cross-layer antenna control protocol based on Open WRT platform.The experimental results show that the average throughput gain of the proposed protocol is up to 45.35% compared with the omnidirectional antenna scheme.Compared with the traversal-based beam training scheme,the beam training consumes reduced by nearly 64%.Aiming at the inefficiency of MAC layer access mechanism,this thesis proposes an adaptive backoff algorithm based on load priority based on the characteristics of ultra high throughput WLAN network architecture.Considering that the gateway nodes and their neighbors as traffic aggregation in the ultra high throughput WLAN often have large collision probability and high traffic load,this thesis uses the cross-layer idea to obtain the statistical information of the carrier layer listening phase of the physical layer and build the priority variable.The busy factor that measures the busyness of the channel enables the nodes with high traffic load to preferentially access the channel,while dynamically controlling the change of the contention window and reducing the probability of collision between nodes.Through simulation analysis,the proposed algorithm has good performance in terms of system throughput,average end-to-end delay and packet loss rate.