Much has been written about 3G LTE versus Wimax for 4G mobile telecoms, but closer observation suggests that the Wimax-LTE battle is just one element of something bigger.
The path to mobile broadband began with the introduction of Wideband Code Division Multiple Access (WCDMA) and moved to High-Speed Packet Access (HSPA).
HSPA enables advanced mobile multimedia services with typical user download rates of either 3.6Mbit/s or 7.2Mbit/s.
More than 96% of WCMDA networks and over 1,875 devices support HSPA.
HSPA has been evolved alongside LTE in all the latest releases from standards organisation 3GPP. The next HSPA generation is HSPA+ (also referred to as “evolved HSPA”). This can support a downlink rate of up to 42Mbit/s using MIMO technology.
The main advantage of HSPA+ is that it is built on top of the original WCDMA networks, enabling data rates to reach 42Mbit/s on a 5MHz carrier, without requiring the same level of investment by the operators as LTE. This is the reason 3GPP decided to continue evolving HSPA+.
It seems that HSPA+ will serve as a transition standard from 3G to 4G until LTE can be fully deployed. As a result, handset manufacturers are focusing on HSPA+ improvements to address the broadband requirements before LTE is accessible to all.
With the evolution and associated processing requirements of HSPA+, it cannot be considered a lightweight 3G standard, but rather comparable to LTE.
The LTE standard introduced in 3GPP Rel-8 uses both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) modes to suit operators’ frequency allocation. Some 90% of available mobile frequencies are in FDD bands.
Nevertheless, LTE-TDD is being pushed in China. And while LTE FDD will be the first to be deployed in the US, LTE-TDD is required by China today. So chip vendors must be flexible enough to support both FDD and TDD for different markets.
3GPP has been defining LTE-Advanced since early 2009 and it is just a question of time until it becomes a reality.
A software-based approach that offers multimode systems support and can replace multiple dedicated baseband systems appears to be the natural direction.
The concept of implementing multiple standards in software can be addressed by software-defined radio. This means a single programmable platform is used to support multiple air interfaces without the need for chip replacements.
Author is Eyal Bergman, director of product marketing at CEVA