Achieving the maximum performance of baseline HSDPA

The current (10/2009) de-facto mobile broadband configuration in commercial HSDPA networks is 7.2 Mbps HSPA which uses only 10 of the available 15 HS-DSCH codes for HSDPA service. Just a couple of years ago this was considered to be an adequate solution: dynamic HS-DSCH code allocation was not widely implemented and the resources for R99 services needed to be ensured. Moreover, there were no terminals with more than 10 codes support available, so upgrading the HSDPA to 15 codes had limited benefits.

During the second half of 2009 a lot has happened in the HSPA ecosystem; new terminals with 15-code support (Cat 9 and Cat 10) have been introduced and a lot more are expected to become available in 2010. Dynamic code and power allocation is becoming a baseline function for radio networks, providing priority to R99 service at any time. Furthermore, many network operators have introduced a second WCDMA carrier in the base stations, providing packet-dedicated carriers. Thus, 15 HS-DSCH codes support for HSDPA is becoming more and more realistic option to increase the network performance.

In this paper we investigate the gains of increasing the number of HS-DSCH codes from 10 to 15 by comparing two different terminal types in the same reference network, namely the HSPA terminal categories 8 and 10. Assuming there is enough transmission and baseband capacity, changing from category 8 to category 10 terminals can result in an increase of peak user bitrates from 7.2 Mbps to 12.8 Mbps. This gain can be achieved without major network software or hardware changes. As the peak bitrate is rather poor KPI for comparing the performance of different technologies, in this whitepaper we analyse the performance of the two solutions in realistic network environment using simulations. In particular we focus on the user data rates that an operator can expect to offer with the given technologies.

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