Modelling the energy efficiency of microcell base stations

The power consumption of wireless access networks will become a major issue in the coming years. Therefore, it is important to have a realistic idea about the power consumption of each element in those access networks. In this paper, an energy efficiency model for microcell base stations is proposed. Based on this model, the energy efficiency of microcell base stations is compared for various wireless technologies, namely mobile WiMAX, HSPA and LTE. The power consumption of microcell base stations is about 70-77% lower than for macrocell base stations but a macrocell base station is more energy-efficient than a microcell base station for the same bit rates. However, for the considered case and assuming our parameters are correct, a reduction in power consumption can be obtained by using microcell base stations to fill coverage holes

Reducing the power consumption in wireless access networks: overview and recommendations

Due to growing importance of wireless access and the steeply growing data volumes being transported, the power consumption of wireless access networks will become an important issue in the coming years. This paper presents a model for this power consumption and investigates three base station types: macrocell, microcell, and femtocell base stations. Based on these models, the coverage effectiveness of the three base station types is compared and the influence of some power reducing techniques such as sleep modes and MIMO (Multiple Input Multiple Output) is evaluated

From Susa to Sippar: the travels of two bulls, a mountain and a tree

Among the Old Babylonian seals of Sippar there is one that appears to be unique. In this study we try to find out whether the motif on this seal was attested elsewhere during the Old Babylonian period and whether it already existed during previous periods. First, we determine the iconographic position of the motif by comparing it to similar ones. Then, by describing the motif’s journey through space and time, we argue that its origin lies in the ancient city of Susa. Finally, we look at the motif’s absence during the Old Babylonian period and link the presence of the motif on a Sippar seal to the fact that it belonged to a Sippar merchant

Cognitive radio systems in LTE networks

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University London.The most important fact in the mobile industry at the moment is that demand for wireless services will continue to expand in the coming years. Therefore, it is vital to find more spectrums through cognitive radios for the growing numbers of services and users. However, the spectrum reallocations, enhanced receivers, shared use, or secondary markets-will not likely, by themselves or in combination, meet the real exponential increases in demand for wireless resources. Network operators will also need to re-examine network architecture, and consider integrating the fibre and wireless networks to address this issue. This thesis involves driving fibre deeper into cognitive networks, deploying microcells connected through fibre infrastructure to the backbone LTE networks, and developing the algorithms for diverting calls between the wireless and fibre systems, introducing new coexistence models, and mobility management. This research addresses the network deployment scenarios to a microcell-aided cognitive network, specifically slicing the spectrum spatially and providing reliable coverage at either tier. The goal of this research is to propose new method of decentralized-to-distributed management techniques that overcomes the spectrum unavailability barrier overhead in ongoing and future deployments of multi-tiered cognitive network architectures. Such adjustments will propose new opportunities in cognitive radio-to-fibre systematic investment strategies. Specific contributions include: 1) Identifying the radio access technologies and radio over fibre solution for cognitive network infrastructure to increase the uplink capacity analysis in two-tier networks. 2) Coexistence of macro and microcells are studied to propose a roadmap for optimising the deployment of cognitive microcells inside LTE macrocells in the case of considering radio over fibre access systems. 3) New method for roaming mobiles moving between microcells and macrocell coverage areas is proposed for managing spectrum handover, operator database, authentication and accounting by introducing the channel assigning agent entity. The ultimate goal is to reduce unnecessary channel adaptation

Self organising cloud cells: a resource efficient network densification strategy

Network densification is envisioned as the key enabler for 2020 vision that requires cellular systems to grow in capacity by hundreds of times to cope with unprecedented traffic growth trends being witnessed since advent of broadband on the move. However, increased energy consumption and complex mobility management associated with network densifications remain as the two main challenges to be addressed before further network densification can be exploited on a wide scale. In the wake of these challenges, this paper proposes and evaluates a novel dense network deployment strategy for increasing the capacity of future cellular systems without sacrificing energy efficiency and compromising mobility performance. Our deployment architecture consists of smart small cells, called cloud nodes, which provide data coverage to individual users on a demand bases while taking into account the spatial and temporal dynamics of user mobility and traffic. The decision to activate the cloud nodes, such that certain performance objectives at system level are targeted, is carried out by the overlaying macrocell based on a fuzzy-logic framework. We also compare the proposed architecture with conventional macrocell only deployment and pure microcell-based dense deployment in terms of blocking probability, handover probability and energy efficiency and discuss and quantify the trade-offs therein