Analysis and Maximization of Throughput Guarantees Offered in Wireless Networks

The field of wireless communications has experienced huge growth in the last decades. Various new user applications have been developed, and the demand for efficient utilization of resources has increased considerably. Opportunistic scheduling schemes can provide higher throughput and increased quality-of-service (QoS) in wireless networks by giving priority to the users with favorable channel conditions. In this dissertation, one of the main goals is to exploit the channel variations of the user channels to design the scheduling algorithms for improved throughput guarantees. Optimization problems are formulated with an aim at finding optimal scheduling algorithms for maximizing throughput guarantees in a wireless network. We show how the solution to such problems can be obtained both when the throughput guarantees are (i) identical and (ii) different for all the mobile users. We also develop the corresponding adaptive scheduling algorithms, both for the scenarios where single user is scheduled per time-slot and where multiple users are selected in each time-slot (e.g. in MIMO systems). The real-world systems based on MobileWiMAX, HSDPA,WINNER I and LTE are considered to analyze the proposed scheduling schemes. Results from simulations show that these algorithms can improve the throughput guarantees in modern cellular networks compared to other well-known scheduling algorithms. Another goal is to analyze the performance loss of such scheduling schemes in the case of imperfect channel information at the base station. We also suggest a rate back-off mechanism to reduce the outage probability in that case. Furthermore, we also propose an approximate expression for the throughput guarantee violation probability to analyze the performance of opportunistic scheduling algorithms without conducting experimental investigations. Such an expression can be very useful for the network providers. Most of the research in joint bandwidth and power allocation for wire-