Neighborhood Small Cells

Qualcomm Research is driving innovation in small cell technology that allows simple plug-and-play deployment while increasing overall network capacity beyond 1000x of today’s macro networks. This new deployment concept, called “Neighborhood Small Cells” (NSC), uses densely deployed open-access small cells and leverages existing premises and backhaul to greatly reduce Capital Expenditure (CapEx) and Operational Expenditure (OpEx).

Our suite of self-organizing network features is known as UltraSON Open™ and is being developed to enable unplanned dense small cell deployments to provide indoor and outdoor coverage. In addition, UltraSON Private™, which helps traditional restricted access small cell operate robustly with the existing macro-small cell network, is now commercialized on Qualcomm FSM chipsets.

Wireless data demand is estimated to grow beyond 1000x in the next decade. Macro cell-splitting will become economically and logistically unfeasible due to the cost of hardware and site acquisition as well as complexity of network planning. Self-organizing small cells will play an integral role in cellular networks and enable operators to meet the 1000x demand challenge. In the NSC model, small cells are deployed in a variety of venues such as:

• Offices and residences (from single-family homes to high-rise buildings)
• Public hotspots (shopping malls, airports, train/subway stations, stadiums)
• Outdoor public areas sites (such as lamp posts)

To validate this deployment model in a dense environment, an NSC test network of 20+ randomly dropped indoor small cells has been set up in San Diego. This UltraSON Open™-powered self organizing network demonstrates continuous coverage inside buildings and around Qualcomm’s campus while maintaining an excellent and seamless user experience.

Neighborhood small cells can be deployed on the same carrier as existing macrocells or on a dedicated carrier. The deployment model is applicable to 3G and LTE networks. Qualcomm Research’s studies show that this new neighborhood small cells network provides huge capacity gains, the extent of which depends on the small cells’ penetration and other factors including the morphology of deployment. With additional spectrum and sufficient density of small cells, it is possible to reach and exceed 1000x today’s network throughput.

Due to the ease of deployment and the fact that customer backhaul and site premises can be leveraged, NSC networks offer tremendous economic benefits in reduced CapEx and OpEx. Just as important, this network model uses standardized small cell architecture adopted by the industry, therefore ensuring full compatibility with legacy networks and mobiles.

To enable plug-and-play deployment and provide the mentioned benefits, Qualcomm is developing UltraSON Open™ feature set to support the following:

Mobility Management Small cells need to discover neighbors autonomously to facilitate UE handover to neighbors. When handover happens, the source small cell can help maintain robustness by streamlining the handover to the target cell. Dense deployment of small cells creates many cell boundaries and lead to potentially more handovers. Frequent handovers can be mitigated by first identifying the cause. If the user is stationary and ping-ponging between small cells, handover parameter adjustments can be done to slow down the handovers. If the user is classified as a fast moving UE, transmissions can be handed over to the macro cell layer.

Tx power Management The RF environment is constantly changing and each small cell needs to adapt its transmit power as small cells are being added, relocated or removed to maintain continuous coverage and avoid pilot pollution.

Resource and Interference Management Small cells deployed in the same channel as macro cells need to coordinate with macro cells to determine the optimal resource partitioning and maximize traffic offloading to small cells. Load balancing and resource partitioning among different small cells is also crucial to improving the user experience.

Backhaul Management Bandwidth of customer-grade backhaul cannot be guaranteed. When small cells experience limit in backhaul bandwidth, they should prioritize user classes as needed.

I Small cell here encompasses what have been known as femtocells, picocells, microcells and metrocells and may be deployed indoor or outdoor.

II The baseline scenario is a macro-only deployment with 500 m ISD and 10 MHz bandwidth in 2 GHz carrier frequency. For the NSC scenario, small cells with 100 MHz bandwidth are deployed in 3.5 GHz carrier frequency. With 144 small cells and 200 users in each macro sector, the DL median user throughput can reach 1000x of the baseline value.