High Speed Packet Access - Overview

Overview

The first HSPA specifications supported increased peak data rates of up to 14 Mbit/s in the downlink and 5.76 Mbit/s in the uplink. It also reduced latency and provided up to five times more system capacity in the downlink and up to twice as much system capacity in the uplink compared to original WCDMA protocols.

These improvements are achieved in several ways:

• Shared-channel transmission, which results in efficient use of available code and power resources in WCDMA
• A shorter Transmission Time Interval (TTI), which reduces round-trip time and improves the tracking of fast channel variations
• Link adaptation, which maximizes channel usage and enables the base station to operate at close to maximum cell power
• Fast scheduling, which prioritizes users with the most favorable channel conditions
• Fast retransmission and soft-combining, which further increase capacity
• 16-QAM and 64-QAM (Quadrature Amplitude Modulation), which yields higher bit-rates
• MIMO, which exploits antenna diversity to provide further improvements in bit-rates and system capacity.

By July 2010, HSPA had been commercially deployed by over 200 operators in more than 80 countries.