HSPA+ (also known as HSPA Evolution) adopts an even higher-order modulation than HSPA (64QAM compared with 16QAM) to boost peak rates further. Performance is further enhanced through the adoption of Multiple Input Multiple Output (MIMO) antenna technology. With MIMO, more than one transmit antenna is used at the base station and more than one receive antenna is used at the mobile device to improve performance.
3G operators are considering deployment of HSPA+ in two ways:
- using a single 5MHz carrier with MIMO. Release 8 combines MIMO with 64QAM modulation to achieve peak theoretical downlink data rates of 42Mbps
- using dual-carrier (10MHz) operation, without MIMO. Release 8 introduces the new multi-carrier operation in the downlink of adjacent carriers. This technique doubles the peak theoretical rate from 21Mbps to 42Mbps without the use of MIMO.
A number of early-mover 3G operators have already made announcements about HSPA+ deployment during 2009 in Asia, Western Europe and the USA.
In October 2008, Telstra in Australia announced that it was upgrading its HSPA network to HSPA+, which it claimed would offer peak downlink speeds of 21Mbps from the end of 2008. Telstra also announced its intention to provide peak downlink speeds with HSPA+ of 42Mbps by the end of 2009. In March 2009, Hong Kong’s 3G operator CSL announced the commercial launch of its HSPA+ services (which it terms ‘Next G’), offering download speeds up to 21Mbps.
In March 2009, Ericsson announced that Mobilkom in Austria had become the first operator in Europe to commercially launch HSPA+, claiming that speeds of up to 28Mbps would be reached in the course of 2009. In December 2008, 3 Scandinavia announced a contract with Ericsson to deploy HSPA+ in selected areas in Sweden and Denmark, starting in the first half of 2009. In February 2009, Telecom Italia announced that HSPA+ (with MIMO) would be rolled out on a nationwide basis in Italy in the second half of 2009, offering download speeds up to 28Mbps.
In January 2009, Vodafone announced the results of HSPA+ trials (without MIMO) in Spain, claiming that it had achieved actual peak data download rates of 16Mbps. In February 2009, further Vodafone HSPA+ trials – this time using MIMO – recorded download speeds in excess of 20Mbps. Vodafone considers that HSPA+ will be capable of delivering a typical video download experience of more than 13Mbps in good conditions and an average speed of more than 4Mbps across a full range of typical cell locations including urban environments. If its HSPA+ trials prove a success, Vodafone plans to make HSPA+ with MIMO available in selected commercial networks.
At Morgan Stanley’s Communications Conference in March 2009, AT&T announced its intention to upgrade its HSPA network to HSPA+ in 2009.
Despite the growing momentum behind HSPA+, some 3G operators may skip HSPA+ and wait for LTE. For example, at the Financial Times World Telecoms Conference in London in November 2008, T-Mobile’s Chief Technology Officer (Joachim Horn) stated that T-Mobile would not deploy HSPA+ and would instead move directly to LTE.