Study the Effect of Base Frequency on the Performance of WiMAX Network Carrying Voice

WiMAX is stand for Worldwide Interoperability for Microwave Access. (WiMAX) embodies the IEEE 802.16 family of standards that provide wireless broadband access to residential and commercial Internet subscribers. This technology takes the first position among the technologies these days. WiMAX can offers or adds some qualifications to the wireless technologies like high data rate, long coverage area and offers several types Quality of service to the customers. The long coverage area of WiMAX coming from the high transmit power and from the architecture of the network which is similar to mobile network, wherethe WiMAX base station architecture, is similar to GSM base station, need tower and can be sectorized,etc. One of the feature of WiMAX devises is the wide range of base frequency from 2 to 66 GHz, on both licensed and free licensed spectrum [1] .In this paper the effect of base frequency on the WiMAX network performance will be studied .we concern on three famous frequency (2.4,3.5 and 5.8GHz ) [2],which most of the WiMAX devises work on them. OPNET MODELER is a simulation program used to simulate the work of networks with different values of base frequency. We use the modeler to study network of 12 WiMAX workstation connect and call each other by one WiMAX base station during 300 second. The results show that the higher the base frequency the higher the Signal to Noise Ratio ,that lead to high throughput ,low packet end to end delay, finally lead to high mean opinion score (MOS) which mean good quality of voice. In the same time the results show that increase in the coverage area will lead to drop in Signal to Noise Ratio and MOS which will effect negatively in the quality of voice.