UE's role in LTE advanced heterogeneous networks

Abstract

Deployment of low-power nodes such as picocells, femtocells, and relay nodes within macrocell coverage is seen as a cost-effective way to increase system capacity and to equip wireless WANs with the ability to keep up with the increasing demand for data capacity. These new types of deployments are commonly referred to as heterogeneous networks and are currently receiving significant attention in industry. However, simple deployment of low-power nodes can lead to underutilization of air-interface resources due to the relatively small footprint of the lowpower nodes or service outage in the case of femto cells with restricted access. Time-domain interference management techniques by the configuration of almost blank subframes, introduced in LTE Rel-10 standards, allow the removal of most of the interference from the dominant interfering nodes. This mechanism enables cell biasing or cell range extension of weak cells, thereby maximizing the incremental gain provided by the deployment of low-power nodes. The configuration of ABS changes the interference conditions seen by the user equipment and therefore requires corresponding resource-specific measurements and feedback at the UE. In this article, we provide an overview of LTE Rel-10 resource specific radio link monitoring, radio resource management, and channel state information feedback procedures. Also, we provide evaluation results to show that UE receivers, in the detection of weak cells and removal of interference in demodulation of control and data channels, play a critical role in realizing the full potential that the deployment of heterogeneous networks can offer.