The analysis by Neu Mobile has demonstrated that as a result of varying conditions, the average capacity of an HSPA 14.4Mbps cell is only 1.8Mbps. This is based on an existing WCDMA 384Kbps network being upgraded as is and assumes a mix of users and an entire 5MHz carrier used for HSPA. The reason for the degradation is two-fold:
- Averaging across the cell: multiple users in the cell each consumer a portion of available capacity. With users on the edge of the cell and indoors requiring a greater portion of the available capacity relative to those closer to centre and outdoors, the total capacity of the cell is reduced.
- Existing networks have been designed for voice and data: current 3G networks were designed for WCDMA 384Kbps or 144Kbps protocols. With HSPA being overlaid on networks designed for slower throughput, the data rate in practice is significantly lower than if the network had been designed purely for HSPA 14.4Mbps.
