Cross-layer Optimization of CDMA Multihop Radio Networks
Student paper other, 20 credits / 30 HE creditsStudent thesis
In this thesis, the problem of finding the jointly Scheduling, Power and Rate allocation for Wireless ad hoc networks is considered. The motivation for this study is limiting multiuser interference in order to increase the total utility, throughput, and spatial reuse of the system. One such algorithm is realized for an S-TDMA (Spatial reuse-Time Division Multiple Access) environment where all communication links share the same frequency band and are power limited. Strong levels of interference inherent to wireless ad hoc network can not be overcome by computationally expensive power control algorithm. Therefore a scheduling algorithm becomes essential to coordinate the transmissions of the users in order to guarantee nonconflicting transmission and an efficient spatial reuse. In this work, firstly an algorithm that tries to simultaneously optimize routing, power/rate control and scheduling for a network composed by fixed nodes and channel gain depend only on distances, is developed. Then, with some modifications, the developed procedure handles node mobility and time-varying flat-fading channel. Numerical results indicate that both ones increase the performances of the system. Furthermore a formulation suitable for the study of energy-constrained networks is introduced. Finally this work investigates the use of multiuser detectors (MUD) in an ad hoc network environment. We demonstrate that multiuser detectors in the terminals give substantial improvements to the total network utility, even when we use very simple schemes for scheduling transmissions.
Place, publisher, year, edition, pages
2004. , 103 p.
IdentifiersURN: urn:nbn:se:kth:diva-109471OAI: oai:DiVA.org:kth-109471DiVA: diva2:582531