Traffic-Driven Energy Efficient Operational Mechanisms in Cellular Access Networks

Emerging smart user terminals and diverse multimedia applications that have driven recent explosive growth in mobile data traffic are increasing energy consumption in cellular networks at an incredible rate. Constituting a significant portion of network operating expenditure and in a context of global warming, rising energy utilization has become a key concern from both economic and environmental perspectives. Consequently, in recent time, the issue of designing energy efficient cellular networks has drawn significant attention, which is also the foremost motivation behind this research. This thesis presents various novel operation mechanisms for single-tier cellular networks designed to enhance the energy efficiency. In a cellular system, base stations (BSs) in the radio access network (RAN) are the most dominant energy consuming equipment estimated between 60%-80%. Therefore, most recently, the idea of attaining a “green cellular network” by reducing energy consumption in BSs has become the spotlight of many researchers. Contemporary BSs consume a considerable amount of energy even at no traffic load. Correspondingly, conventional cellular networks, which are provisioned based on peak-traffic load without accounting for inherent high-degree temporal-spatial traffic diversity, are wasting a significant amount of electrical energy, especially during low-traffic periods. Considering these facts, the proposed research is focused on the design of traffic-sensitive dynamic network reconfiguring mechanisms for energy efficiency in cellular systems. Under the proposed techniques, RANs are adaptively reconfigured using less equipment leading to reduced energy utilization. At the same time, quality of service (QoS) is guaranteed within the target limits. The proposed mechanisms work in a self-organizing fashion requiring no operator assistance. The main contributions of this thesis can be summarized as below: • An energy efficient cellular network framework by employing distributed inter-BS cooperation in a RAN is proposed. Under this framework, based on the instantaneous traffic demand, BSs mutually cooperate for dynamically switching between active and sleep modes by redistributing traffic among themselves and thus, energy savings is achieved. The focus is then extended to exploiting the availability of multiple cellular networks for extracting energy savings through inter-RAN cooperation. Two alternative mutual cooperation mechanisms among BSs belonging