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HSPA+ Advanced

HetNets

To accommodate the rapidly increasing demand for data on cellular networks, operators need to find solutions to improve coverage as well as capacity. Cell splitting to add capacity is not feasible in most dense urban areas where Inter Site Distance (ISD) is already very small. Site acquisition and logistics make this increasingly unviable. A promising approach to improve capacity is Heterogeneous Networks (HetNets), in which low power nodes (micro cells and pico cells) are deployed at traffic hotspots within macro cells.

HetNets, consisting of Macro NodeBs and low power Pico NodeBs, can significantly increase system capacity by offloading a substantial portion of the macro cell users to pico cells. However, this offloading may be limited due to inter-cell interference from macros to picos that reduces their coverage in a co-channel deployment (macro and picos on the same frequency).

Multi-carrier HSPA+ enables the use of the following HetNets techniques to achieve greater offloading:

  • Dual Cell Pico Range Expansion: A technique where power on the secondary carrier on the macro is reduced to allow the pico cell to expand its coverage, thus allowing greater offloading of users from the macro to the pico.
  • Multiflow Dual Frequency Dual Cell (DFDC): Use the two best links, regardless of which cell and frequency they happen to be on. More information is available on the HSPA+ Multiflow page.
  • Load based serving cell selection: Choose the best serving cell based on current radio and loading conditions and not just radio conditions.

Qualcomm was the first company to demonstrate HSPA+ HetNets gains from Range Expansion and DFDC techniques at Mobile World Congress 2012.

Further details of this research are available in the whitepapers on this page.