| The next-generation Wireless Local Area Network(WLAN)standard,802.11be(Wi-Fi7),is committed to providing extremely high throughput of at least 30 Gbps and support for latency-sensitive applications.To achieve its goal,802.11 be introduces the key technology of multi-link transmission for the first time,i.e.,a device can use multiple links for data transmission or reception at the same time.However,in a busy network,a multi-link device is likely to send or receive data on only one link at the same moment,not fully utilizing the advantages of its multiple links.In order to utilize the device resources more efficiently,802.11 be proposes an enhanced multi-link single radio operation,when a terminal device acquires a transmission opportunity on one link,if another link cannot operate at the same time,the device can apply the mechanism to switch the spatial stream resources on the second link to the first link,thus increasing the transmission efficiency of the first link.In this thesis,the following two aspects of the enhanced multi-link single radio operation for802.11 be are investigated.For the problem of missing uplink data transmission mechanism in the current enhanced multi-link single radio operation,an uplink enhanced multi-link transmission mechanism is proposed in this thesis.After terminal devices compete for channel resources,if spatial stream switching is performed first,the channel will be detected as idle by other devices during the switching period,so the channel is likely to be seized by other devices.In the existing downlink data transmission mechanism,the access point reserves time for the terminal device to complete the spatial stream switching by sending and padding the initial control frame.The advantage of this solution is that the terminal device completes the spatial stream switching during the interaction of the initial control frame and the response frame,without additional operations and reducing the spatial stream switching overhead.However,the initial control frame is a trigger type frame,which the current standard does not allow terminal devices to send.For this reason,a new time reservation method is included in the proposed mechanism.In this method,the terminal device sends a frame sequence that conforms to the standard to occupy the channel,so as to reserve time for the device to complete the spatial stream switching.Simulation experiments analyze the performance of the uplink enhanced multi-link transmission mechanism,and the results show that the enhanced multi-link transmission mechanism can effectively improve the link rate and reduce the transmission delay due to the full utilization of spatial stream resources.An adaptive selection algorithm of device transmission mode is proposed based on the reinforcement learning algorithm.When a terminal device acquires transmission opportunities on a link,it selects the optimal transmission mode: traditional multi-link mode or enhanced multi-link single radio mode,taking into account the current service demand,the number of spatial streams,and the busyness of each link.When the network environment is idle,the spatial stream switching delay is long and one transmission opportunity is short,the terminal gives priority to the traditional multi-link transmission mechanism to improve the utilization of the link;if the network environment is busy and it is difficult to aggregate two links,the enhanced multi-link single radio transmission mode is preferred to improve the utilization of the spatial stream.Simulation results show that the enhanced multi-link transmission algorithm based on reinforcement learning can effectively improve the performance of the device in terms of throughput and latency. |
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