| IEEE started research on the new generation of WLAN standard in 2013,and completed the formal release of the 802.11 ax protocol in 2019.Compared with the previous protocol change,the network throughput has been improved,and the user experience in the dense deployment of stations has also been improved.The agreement introduces new technologies such as Orthogonal Frequency Division Multiple Access(OFDMA),MU-MIMO,and 1024 QAM,which significantly increases the transmission rate of the physical layer.Changes to the physical layer require the MAC layer to introduce a new access mechanism to adapt,and the control frame as the frame type that the MAC layer assists in data transmission also needs to be adjusted.Compared with the previous generation 802.11 ac protocol,the 802.11 ax protocol introduces OFDMA technology,which greatly increases the transmission rate by dividing sub-channels.In the past,only one station and the access point were performing data transmission at the same time.Nowadays,multiple stations can be implemented concurrently.In order to realize the scheduling of multiple stations,the MAC layer,which is responsible for controlling data forwarding and storage,introduces the trigger frame.Access point can allocate channel resources by sending the trigger frame.The new mechanism has an impact on the MAC layer on the station side.In order to cope with the increasingly complex channel access mechanism and speed up the development of the MAC layer,this article puts forward the idea of making the transmission and reception of control frames an independent module,and finally completes the design of transmission and reception of MAC layer control frames on the station side with reference to the next-generation WLAN standard.This subject comes from the Wi-Fi chip project of my internship company,The main research contents of the paper are as follows:(1)This thesis analyses the research status of the 802.11 protocol firstly,and demonstrates the advantages of related technologies of the 802.11 ax protocol through comparison.Then the second chapter introduces the MAC layer access mechanism and frame structure technology.These are the technical basis for the design of control frame module.(2)The third chapter firstly plans the function of the control frame generation module,with combining the types and characteristics of input and output data we works out the specific structure of the module,and then we starts a detailed analysis of the functional principle of each sub-module.Through the demonstration of the verilog code and data flow diagrams the study preliminarily proved the feasibility of the scheme.(3)The work of Chapter 4 revolves around the verification and logic synthesis of the module.First,the framework of the MAC layer is built according to the protocol to provide a verification environment for the designed module.After that,various simulations of the control frame generation module was completed by the simulation environment and tools of the company.The simulation work firstly detects whether the internal logic of the module can complete the assembly of the control frame,and then instantiates the module at the MAC layer to verify whether it can assist in the transmission and reception of data frames correctly.Finally,the simulation waveform of the control frame generation module in the process of data transmission is obtained.In summary,this thesis planned the module structure of the MAC layer according to the content of the 802.11 ax protocol and completed the RTL design of the control frame generation module,and then set up a verification environment to complete the simulation verification work for the module,which proved the feasibility of the scheme from both RX and TX directions.Finally the logic synthesis was completed,which proved that the designed module can run normally under the 80 MHz clock and can serve the Wi-Fi chip of stations. |
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