Bit error rate estimation in WiMAX communications at vehicular speeds using Nakagami-m fading model

The wireless communication industry has experienced a rapid technological evolution from its basic first generation (1G) wireless systems to the latest fourth generation (4G) wireless broadband systems. Wireless broadband systems are becoming increasingly popular with consumers and the technological strength of 4G has played a major role behind the success of wireless broadband systems. The IEEE 802.16m standard of the Worldwide Interoperability for Microwave Access (WiMAX) has been accepted as a 4G standard by the Institute of Electrical and Electronics Engineers in 2011. The IEEE 802.16m is fully optimised for wireless communications in fixed environments and can deliver very high throughput and excellent quality of service. In mobile communication environments however, WiMAX consumers experience a graceful degradation of service as a direct function of vehicular speeds. At high vehicular speeds, the throughput drops in WiMAX systems and unless proactive measures such as forward error control and packet size optimisation are adopted and properly adjusted, many applications cannot be facilitated at high vehicular speeds in WiMAX communications. For any proactive measure, bit error rate estimation as a function of vehicular speed, serves as a useful tool. In this thesis, we present an analytical model for bit error rate estimation in WiMAX communications using the Nakagami-m fading model. We also show, through an analysis of the data collected from a practical WiMAX system, that the Nakagami-m model can be made adaptive as a function of speed, to represent fading in fixed environments as well as mobile environments

Performance Analysis and Resource Allocation in MIMO-OFDM Systems

The paper deals with the analysis of the vital performance plot of SNR and BER in MIMO systems. The importance of the diversity orders and the variation of the SNR-BER plot with respect to it is also studied using the simulation outputs. The three types of fading channels are also analysed. It is also seen that the presence of diversity and other schemes like Maximal Ratio Combining, selection combining, alamouti scheme increases the overall efficiency. The importance of the optimisation techniques and the superiority of the Monte Carlo optimization to the theoretical system without optimisation is also clearly visualised. The paper also deals with resource allocation in MIMO-OFDM systems. The advantage of the constant envelope OFDM over OFDM is achieved. Also the power allocation using water-filling algorithm and bandwidth-power product minimisation is compared using the obtained results