Autonomous Cellular Networks
A cellular network is formed by the deployment of a set of base stations (BSs) across the network coverage area. Based on the cellular concept - proposed in the late 1970s - the BSs are (more or less) uniformly deployed in a hexagonal pattern. For over three decades almost all research in this field was conducted with the assumption that all BSs are regularly deployed. Most of the effort in achieving better service was heavily invested in finding better modulation and coding schemes. Today the available transmission techniques achieve capacities incredibly close to the theoretical limit. Hence in order to satisfy the unprecedented explosion in the wireless service demand, new avenues should be explored.
In a typical urban cellular network, each BS covers an area with a radius in the range of 100 - 1000 meters. A network with a regular deployment pattern, however with a much smaller cell radius, can potentially satisfy the future requirements. Scaling down the size of each cell does not substantially affect the signal-to-interference-plus-noise ratio (SINR) of each link. However, with the reduction of the cell coverage area, the number of served terminals per BS drops significantly. Each BS allocates more system resources to each terminal, which in turn results in a larger aggregate throughput for the end-user. In practice however, a considerable reduction in the cell size translates into a highly dense regular deployment of BSs. The deployment of such an infrastructure will not only be prohibitively expensive but in most cases simply not feasible due to restrictions on the location of the base stations.
Alternatively, the network can be constructed by a BS deployment based on local traffic demand. Although this approach is indeed more practical, major new design challenges arise. The irregularity of the BS locations potentially can result in excessive interference between the BSs which in turn can significantly disrupt the network performance. Albeit, irregular deployment of large and small BSs according to local traffic demand is widely accepted as the only solution to satisfy the ever-increasing demand for wireless service. This major paradigm shift in the model and deployment of cellular networks has resulted in many exciting new challenges in the design and resource allocation strategies for future cellular networks.