Motorola recently released the results of a trial of high-speed downlink packet access equipment conducted in Europe, as well as suggested guidelines based on the findings.

The company said HSDPA — the next generation of wideband CDMA that promises downlink rates between 2 Mb/s and 14.4 Mb/s — is prone to delays when users are Web-browsing, because of a mechanism that moves users from high speed to low speed based on user activity, without the user being aware of the transition. The problem does not appear to occur when users are engaged in mobile applications.

Motorola suggested eliminating the “state switching” function altogether because HSDPA enables radio resources to be “dynamically shared” between users. However, this capability, known as “scheduling,” requires intensive computer programming at the base station, so Motorola further suggested that operators ensure that base stations have the appropriate processing power.

In addition, HSDPA performance depends heavily on device capabilities, according to the trial results. While the trial demonstrated that devices capable of a signal-processing function known as equalisation show data rates up to 40% higher, only a few device manufacturers claim that functionality, Motorola said.

Also, video-streaming performance degrades when a small set of users are active. Motorola suggested that operators either prioritize video services or provide more capacity to compensate.