By Naveendra Thiyagarajah PhD, DIC, PA wireless expert
Projected penetration of LTE in huge segments of the world market is still sluggish. The predicted worldwide mobile connections by technology, shown in the figure, does not show the expected LTE dominance in Asia Pacific and China (APAC), Latin America (LA), Central and Eastern Europe (CEE), Middle East and Africa (MEA) – a significant presence of WCDMA/HSPA and GSM/EDGE is expected beyond the next 5 years.
In these markets WCDMA/HSPA and GSM/EDGE were introduced relatively recently and operators may still not have recouped their investment in these technologies and will be very reluctant to overhaul their infrastructure outright, just yet. But how would they support the ever increasing demand for data (and voice) capacity? These operators would seek higher capacity using their existing 2G/3G equipment and then seek a way to migrate to LTE.
GSM/EDGE 2G and HSPA 3G technologies are still evolving within 3GPP, with major enhancements proposed for both handsets and base stations promising increased spectrum efficiency. Innovations proposed for GSM (VAMOS – two users sharing the RF channel) and HSPA (Frame Early Termination – early decode of voice frames, New Frame format – two users multiplex time slots, Enhanced Voice Service SC-VBR codec – low bit rate voice codec) promise up to 100% and 30% spectral efficiency gains respectively compared to legacy systems. Moreover, the proposed techniques can be incorporated into legacy systems via software changes, without having to change expensive hardware.Therefore migration to encompass these new enhancements is cheap and relatively quick.
Enhanced spectral efficiency allows operators to increase their 2G/3G voice and data capacity and/or reallocate parts of their 2G/3G spectrum to LTE (while simultaneously maintaining voice capacity and competitive 2G/3G data speeds). Even in markets where LTE deployment is mature for data, voice capacity is still required from 2G/3G because of holes in LTE coverage area and limited availability of VoLTE. Availability of spectral efficiency enhancements blows new life into 2G/3G systems and operators would want to prolong the life of their 2G and 3G infrastructure by having their systems enhanced.
Prioritising the development of LTE over enhancements to 2G and 3G may leave infrastructure and test equipment manufacturers unable to service a huge worldwide market. Infrastructure manufacturers need to make parallel development efforts across 2G to 4G. They should rapidly bring to market the innovations proposed in 3GPP for 2G and 3G. Their development efforts should not concentrate solely on standalone LTE solutions anymore.
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