Resource Allocation and Performance Optimization in Wireless Networks

Abstract

In the past few years, demand has kept increasing for higher data rates in wireless networks due to the increases in the numbers of mobile subscribers and multimedia applications. Femtocell and free space optics(FSO) networks, which both are important solutions to build next generation wireless networks, are two networks studied in this dissertation. In this dissertation, we adopt optimization approaches for network design in both femtocell and FSO networks. The first part of this dissertation provides an introduction to the background and related research issues of the femtocell and FSO networks. In the first two chapters, cell association, handover management and scheduling policies in two-tier femtocell networks are studied extensively. Cell association problem is to associate users to either a macro base station(MBS) or a femtocell base station(FBS). The objectives of cell association problem can be: 1) Maximizing total network throughput; 2) Achieving fairness among all users; 3) Balancing load among all BSs. Cell association and handover algorithms are proposed to achieve these objectives. In the following chapters, research is extended to Free space optical (FSO) networking, which is an attractive energy-efficient technology with applications ranging from high capacity military communications to “Last-mile” broadband access solutions. Topology control, spatial diversity techniques and adaptive transmissions in FSO systems are studied to mitigate weather turbulence which greatly degrades link performance. The problem of building a spanning tree when number of transceivers on each base station is limited in FSO networks is first studied. Then, the challenging problem of relay selection and power allocation in cooperative FSO network is investigated. Last but not the least, the problem of optical power allocation under power budget and eye safety constraints is investigated for adaptive WDM transmission to combat the effect of weather turbulence in FSO networks. This research provides new visions for practical solutions to mitigate weather turbulence in FSO networks.