Abstract
Cell size in cellular networks is in general fixed based on the estimated traffic load. However, the traffic load can have significant spatial and temporal fluctuations, which bring both challenges and opportunities to the planning and operating of cellular networks. This article introduces a concept of cell zooming, which adaptively adjusts the cell size according to traffic load, user requirements and channel conditions. The implementation issues of cell zooming are then presented. Finally a usage case of cell zooming for energy saving is investigated. Centralized and distributed cell zooming algorithms are developed, and simulation results show that the proposed algorithms can greatly reduce the energy consumption, which leads to green cellular networks.
INTRODUCTION
Wireless cellular networks have been growing rapidly in the last few decades. The subscriber number and traffic volume in cellular networks have explosively increased. Network operators are always trying their best to satisfy user requirements cost-efficiently. In each cell, the base station (BS) transmits common control signals and data signals to mobile users (MUs), and the cell size is defined as the area in which MUs can receive control signals from the BS. At the stage of network planning, cell size and capacity are usually fixed based on the estimation of peak traffic load.
CONCLUSION
In this article, the concept of cell zooming is proposed, which is to adaptively adjust the cell size according to the traffic load fluctuations. Cell zooming can not only solve the problem of traffic imbalance, but also reduce the energy consumption in cellular networks. Techniques such as physical adjustments, BS cooperation, and relaying can be used to implement cell zooming. In the case study of cell zooming for energy saving, we show that the proposed cell zooming algorithms can leverage the trade-off between energy saving and blocking probability. The algorithms also save a large amount of energy when traffic load is light, which can achieve the purpose of green cellular network in a cost efficient way
