Research On Cell Zooming Technology In LTE Systems

With the development of wireless communication technology, in order to meet the high data rates and quality of access, more and more new technology has been brought into the existing systems and more and more base stations (BS) have been deployed. At the traditional stage of network planning, cell size and capacity are usually fixed based on the estimation of peak traffic load. However, traffic load in cellular networks can have significant spatial and temporal fluctuations due to user mobility and burst nature of many data applications. So the traditional power scheme of base station will result in a huge waste of energy.Green communication has been drawn more and more attention in recent years, which aims to design efficient power control or switch on/off scheme of base station for energy saving. In the study of green communication, the concept of "cell zooming", which adaptively adjusts the cell size according to traffic conditions, has become a spot in this research area. Cell zooming has the potential to balance the traffic load and reduce the energy consumption.In this thesis, the technology of cell zooming in LTE systems is researched. Firstly, the background the technology of cell zooming and the current research situation are given. Secondly, a dynamic switch on/off scheme for base station based on the capabilities of users for carrier aggregation in LTE-Advanced systems in order to minimize the energy consumption for the base station is presented in this part. In the proposed scheme, the base station provides the adaptive transmitted power to the users according to their capabilities of carrier aggregation, which is different from the traditional ones that the BS serves all arrival users with the same possible maximum transmitted power. Simulation results demonstrate the proposed dynamic switch on/off scheme can significantly reduce energy consumption and improve the energy efficiency under different traffic conditions compared to the traditional scheme. Besides, a joint cell zooming scheme of BS switching and power control in LTE systems is presented in this thesis. By partitioning each cell into cell partitions, the inter-cell interference and location-dependent users’ QoS can be explicitly modeled, which are the minimum requirement of data rate and the block probability. Then a best BS switching mechanism based on the current traffic load that can maintain users’QoS constraints for energy saving is shown. Further on, a power control algorithm using non-cooperative game theory for all the active BSs under the chosen configuration of BSs is proposed. Simulation results demonstrate the presented joint scheme can achieve energy saving.