The Key Technologies Of The Wimax Physical Layer

Wireless broadband communication is developing with higher rate, wider ranging and mobility. WiMAX technology satisfies the need of wireless Internet. WLAN resolves the problem of last one hundred mile access, then WiMAX will become the best scheme of last one kilometer access. WiMAX supports the fix and mobile access and contain two standards: IEEE802.16d (IEEE802.16-2004) and IEEE802.16e. IEEE802.16d supports fix broadband wireless access and IEEE802.16e supports fix and mobile broadband wireless access.WiMAX PHY contains three kinds structures: SCa PHY, OFDM PHY and OFDMA PHY. This paper analyzes OFDM PHY and OFDMA PHY. Combined with IEEE802.16-2004, this paper designs a simple OFDM receiver with the component of frame start synchronizer, frequency carrier estimator, phase track and channel estimation. WiMAX uses the OFDMA to implement the multi user communication. Furthermore, scalable OFDMA has been used in draft of IEEE802.16e for mobility.This paper also analyzes adaptive bits allocation and power allocation technology. For every OFDM symbol, it applies a flexible arithmetic in the model of IEEE802.16-2004 PHY. Through simulation, more than four dB has been improved.