• 802.16e
• permutation zones
• scheduling
• wimax

WiMAX (Worldwide Interoperability for Microwave Access) , based on the IEEE 802.16 standard, defines wireless networks
combining key characteristics of wide-area cellular networks as well as short-range networks, namely mobility and high data throughput.
The current Mobile WiMAX technology is mainly based on the IEEE 802.16e amendment, which specifies the Orthogonal Frequency Division Multiple Access (OFDMA) air interface and provides support for mobility.
IEEE 802.16e OFDMA standard provides for subchannelization techniques as a means to better manage network performance to address specific coverage and capacity requirements.
Subchannels may be constituted using different permutation schemes to exploit frequency diversity or frequency selectivity.
A number of contiguous OFDMA symbols, in the downlink frame or the uplink frame, that use the same permutation scheme constitute a permutation zone.
The Down Link (DL) subframe or the Up Link (UL) subframe may contain more than one permutation zone.
The first section of this work analyses the main issues connected with the presence and the management of multiple permutation zones within the DL WiMAX subframe. In the second section some possible multi-zone scheduling algorithms are proposed and implemented. The final section analyses and evaluates the performance of various schedulers.
The appendix reports the work done for implementing support to SUB-DL-UL-MAP MAC messages within the ns-2 WiMAX simulator, and analyses the improvements deriving from their use.