LTE Advanced Heterogeneous Networks (HetNets) use a mix of macro, pico, femto and relay base-stations, effectively bringing the network closer to the user. To deliver high spectral efficiency per unit area, advanced techniques are needed to manage and control interference when low power small cells are added to macro cells in the same channel. Qualcomm has developed two LTE Advanced techniques, enhanced inter-cell interference coordination and advanced terminal receivers with interference cancellation (eICIC/IC) to provide a performance leap for heterogeneous networks in LTE.
LTE Advanced HetNets will support Range Expansion and Resource Partitioning with an eICIC software upgrade to a LTE-R8 network. Range Expansion allows more user terminals to benefit directly from low-power base-stations such as picos, femtos, and relays. Adaptive inter-cell interference coordination using Resource Partitioning provides smart resource allocation amongst interfering cells and improves inter-cell load balancing in heterogeneous networks. Advanced UE receivers cancel interference of legacy overhead channels from interfering cells to enable full Range Expansion of low power small cells.
The eICIC feature has been standardized in 3GPP Rel-10 under the LTE Advanced framework. Qualcomm R&D, along with other 3GPP participants, are leading the standardization of HetNets features. Qualcomm R&D has also built a prototype to demonstrate and test these features in OTA heterogeneous networks in San Diego.
For an LTE operator that needs to significantly increase network capacity, deploying LTE Advanced HetNets and using 802.11 Wi-Fi access points (APs) in unlicensed spectrum offer two complementary options to offload macro user traffic. Based on our study, with the same number of low-power nodes, pico cells offer a superior performance than Wi-Fi APs due to expanded coverage of LTE Advanced pico cells. Wi-Fi is effective in improving user experience when a significant portion of users are located in the vicinity of hotspots.