Fixed-point Implementation Of 802.11ax Prototype Simulation System

With the rapid development of IEEE 802.11 WLAN,data consumption,wireless devices in limited environment and requirements for uplink applications have increased greatly.In order for the improvements of the user experience,support for various dense environment,and the throughput of the whole system,the study group for next generation of WLAN standard(802.11ax)was founded by IEEE in 2013.To develop the 10 G WIFI prototype and traverse technologies like OFDMA and UL MU-MIMO which is mainly introduced by 802.11 ax,an 802.11 ax prototype physical multi-user simulation system is built based on the related proposals of 802.11 ax,and technologies like OFDMA and UL MU-MIMO are simulated based on this system.Then,the float-point simulation system is modified into a fixed-point simulation system,which can provide fixed-point scheme and data comparison for 802.11 ax prototype hardware implementation.The simulation system is mainly built based on MATLAB platform,and some modules are from the development kits System Generator provided by Xilinx.In this paper,we mainly study multi-user transmission in 40 MHz band.Firstly,the main receiving process of three multi-user transmission mode in 40 MHz band(two-user OFDMA,UL MU-MIMO and transmission combining OFDMA with UL MU-MIMO)is designed.Then,we design the multi-user transmitter and receiver,especially the receiver algorithm design and optimization in multi-user mode,which includes multi-user mode discrimination,timing synchronization,frequency offset compensation,phase tracking,MIMO detection,data detection and et al.Based on float-point simulation system,fixed-point schemes are designed for all modules,especially timing synchronization,channel estimation and MIMO detection.At last,the 802.11 ax prototype multi-user fixed-point simulation system is built.In this paper,performance tests for both 802.11 ax prototype multi-user float-point system and fixed-point system are carried out.This multi-user system can realize the concurrent transceiving for at most sixteen users,which greatly increases the number of uplink concurrent users.At the same time,the performance difference between float-point and fixed-point systems are compared among various signal-to-noise ratio.