Abstract: IEEE 802.11aj is a standard of next generation wireless local area network（WLAN） for millimeter wave band (45GHz) of China. A structure of physical layer and a structure of transmitter are designed for communication system. This paper made a research on a new scheme of cyclic shift diversity for IEEE 802.11aj standard. The scheme can achieve good performance without additional effort at the receiver. In addition, this paper made an analysis on the performance of all modulation and coding schemes. In conclusion, in order to limit the transmitting power at 20dB，the 16-QAM modulation of rate-1/2 could achieve high throughput ensuring the PER performance at the same time.