OPINIONS

Gain of Dual‐Cell HSDPA in Macrocellular HSPA+

The current (09/2010) de‐facto mobile broadband in commercial HSDPA networks is the 7.2 Mbps solution defined in 3GPP Release 5. During the end of year 2009 and the first half of 2010 a lot has happened in HSPA; new terminals with 15‐code support (Category 9 and Category 10) and 64QAM (Category 14) are widely available. Several networks are supporting peak data rates of 14.4Mbps or more. An advanced HSPA network can theoretically support up to 21Mbps or 42Mbps with a single 5MHz carrier in Release 7 (64QAM) and Release 8 (64QAM+MIMO) respectively. An alternative method to double the highest achievable data rates is to increase the bandwidth of the channel. That is, to combine two 5 MHz WCDMA carriers simultaneously for a single user, with DC‐HSDPA, instead of only one carrier.

Dual‐Cell HSDPA (aka. Dual‐Carrier HSDPA) is a wireless broadband standard based on HSPA that is defined in 3GPP Release 8. DC‐HSDPA is the natural evolution of HSPA by means of carrier aggregation in the downlink. The basic idea of the feature is to achieve:

  • Higher peak data rates in the radio interface by aggregating the carriers for a single user
  • Increased system capacity by scheduling also in the frequency domain

Omnitele has studied the performance of Release 8 DC HSDPA by theoretical studies and network simulations. This study is presented in three sections. First, the achievable user bitrate gains of DC are studied without assuming any increased system capacity. In the second section, the increased system capacity of DC, by increased spectral efficiency (bit/s/Hz), is analyzed. The third and final section presents an example simulation case in a typical suburban network environment.

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