Quantitative Analysis of Multihop CDMA Cellular Networks

Abstract

Multihop Cellular Networks (MCNs) form combined wireless paradigm that carries the advantages of both traditional cellular networks and wireless multihop relay. Cellular networks depend on a fixed infrastructure to provide wide area coverage for users with high mobility profile. Multihop relay networks depend on wireless devices inside the network to relay signals through multiple hops from source to destination. MCNs were proposed to overcome inherent drawbacks in cellular networks like congestion and dead spots. These gains build on the characteristics of multihop relay that result in increased capacity, decrease energy depletion and virtually extended coverage. But while these gains have been widely accepted and advocated, they have not been verified in rigor. A realistic need therefore exists to quantify these gains in order to realize more capable network management functionalities for this new paradigm. In this thesis, we present an analytical framework for MCNs. We quantify the capacity and energy consumption in MCNs, while considering various call distributions, network loads and transmission power. We apply our framework to Code Division Multiple Access (CDMA) cellular networks, which are very dependent on interference levels in their performance. Our results show that capacity can be increased in CDMA cellular networks using multihop relay by increasing either the number of simultaneous calls or data rates. We also demonstrate that consumed energy is decreased in MCNs, especially in environments with high path loss. We validate that multihop relay is most rewarding when calls tend to originate near cell borders. Beyond verifying basic claims, we explore other potential gains of MCNs. We investigate the viability of congestion relief and load balancing and substantiate the benefits for congested cells neighbored by lightly loaded cells. Load balancing has also been shown to increase data rates and fairness in user allocations. Lastly, we explore enabling multimedia applications in MCNs and study the application of data rate adaptations given multiple classes of service. A key advantage of our work is that, while applied to CDMA in this thesis, the presented analytical framework can be extended to other technologies. The framework also accommodates both mobile and fixed network relay elements, expanding its applicability to next generation cellular networks.