Propagation models for WiMAX at 3.5 GHz

Networks based on WiMAX (Worldwide Interoperability for Microwave Access) provide efficient packet radio interface. These networks enable high data transmission rates. WiMAX is the newest wireless broadband Internet technology based on IEEE 802.16 standard. Based on OFDM (Orthogonal Frequency Division Multiplexing), this system uses radio frequency range from 2 to 11 GHz. Calculation of path loss is very important, because it gives approximate values compared to any, obtained from real measurements. So it is helpful for initial deployment of WiMAX networks, providing an opportunity for cell planning. In this paper I discuss and compare following path loss models - Free Space Path Loss Model (FSPL Model), Hata-Okumura Extended Model (called also ECC-33 Model), Cost 231 Walfish-Ikegami Model and Stanford University Interim Model. In this paper I take the information on the location of buildings, the height of the transmitting antenna, receiving antenna and the others, consistent with conditions in Bulgaria. In each country, there are portions of the spectrum set aside for commercial purposes. In Europe and much of Asia, the 3.5 GHz spectrum range is used for broadband wireless, so I make calculations for 3.5 GHz. From calculations, that I made, can be concluded, that FSPL model, gives the lowest path loss, in all type of terrains - rural, suburban and rural areas. Model ECC-33 can predict path loss in urban and suburban areas, but it is unusable in rural areas. Also I can conclude, that model SUI, has approximately the same values of path loss with those, computed with FSPL model. My research shows that all four models for calculating the path loss are applicable to various areas, and we must compromise between coverage area and low interference of the transmitted signals, when we design WiMAX network.