Impact of Co-Channel Small Cell Deployments on Achievability of Uplink Target SINRs In WCDMA Heterogeneous Networks

The operation of macro-cells can be cost and resource-efficiently supported by secondary small cells that are deployed on-demand in traffic hotspots within the coverage area of the primary base stations. In view of the growing traffic demand and the limited spectrum available, the objective of this paper is to examine the conditions under which the secondary base stations can share the same communication channel with the primary base stations under the constraint of a predefined quality of service. Considering the more complex uplink transmission mode with the requirement of a minimum predefined signal-to-interference-and-noise ratio (SINR) for all active transmissions in the common interference-limited channel, we formally assess the impact of the secondary infrastructure on the global achievability of the SINR targets via distributed closed-loop power control. In particular, the effects of intra-cell load and inter-cell coupling are investigated with the aim of providing deployment guidelines for the secondary small-cell infrastructure, as well as the development of algorithms for base station auto-configuration. Analytical conclusions are validated numerically by simulations.