Many operators have said they are “committed to deploy LTE,” but when pressed for details they often say that they have no firm plans and that deployments will likely be in the 2013-2015 time frame.

HSPA+/HSPA Advanced has been considered for some time. Some of the advantages include: an HSPA+ network is backward compatible with HSPA - thus the existing HSPA handsets will continue to work; new HSPA+ handsets that include MIMO capabilities can be offered with higher bandwidth and level of service; the base stations for all leading vendors are software upgradeable, although they do typically require new head-end RF units with MIMO-AAS capability. These factors result in a lower cost and more seamless upgrade than the transition to the new LTE RAN.

LTE makes all existing handsets unable to work. Users have to be either transitioned over the normal upgrade turnover time period for new multimode phones or provided with new phones in a more rapid swap out. If the operator causes the more rapid swap out sequenced transition, they have to pay users to upgrade or face defections to other operators. When a new class of service is offered, initially only a small percentage of users opt for the service.

The issue is made more complicated by the fact that HSPA+ provides bandwidth that is close to that provided by 3G-LTE. That raises the question: why make a move to LTE? Because the situation of operators varies, the answer has to factor in the demographics, nature and duration of existing infrastructure (if major upgrades of core networks are needed then a shift to a next generation network may make more sense). Part of the reason to move to LTE (or WiMAX) is that these networks will become the long-term evolutionary path to even higher bandwidths. However, many carriers do not need this for their mobile operations.

If the operator also wants to supply enterprise data networking, HDTV quality video and other bandwidth intensive applications or if competitive usage demand grows on mobile networks at a similar pace as seen on wired Internet connections, then operators may find themselves in a battle with a competitor who does offer LTE or WiMAX. That is the scenario that Clearwire hopes to see develop: the demand for bandwidth continuing to grow to the point that their service is prized by a significant portion of consumers compared to the more proven mobile capabilities of 3G-3.5G (HSPA+) networks.

Similarly, 3G-LTE and WiMAX might be pegged as similar to HSPA+ at 3.5G or perhaps a bit higher, but certainly not 4G.
LTE is a more complicated decision than whether the bandwidth is improved over HSPA+ or the handset transition issue: both LTE and WiMAX are flat IP networks that incorporate QoS and can provide very good VoIP service. WiMAX, according to independent studies, can provide slightly higher VoIP capacity than LTE but this can be expected to change as refinements are made and new generations of the standards emerge; they should become similar enough in VoIP capacity not to be a significant long-term issue. What is a major issue for 2G-3G operators is how they maintain current revenue: if customers are transitioned to VoIP they will likely expect it to provide unlimited calling similar to Internet broadband based VoIP service plans.

The technical solution is a matter of working out bugs over time. There are no fundamental reasons for LTE or WiMAX not to deliver very good quality VoIP service; in fact, true stereo quality VoIP is possible. VoIP requires good end-to-end QoS, particularly low latency and jitter. If either the WiMAX or LTE network offer good QoS but somewhere along the way the connection to the other side of the communication does not, the VoIP service suffers accordingly. Anyone who has used VoIP phones on DSL cable has likely experienced calls to far away places that were fine, while calls to destinations only a few hundred or thousand miles away were unusable.

Several factors weigh into decisions about what network makes sense for new deployments vs. upgrades. The transition of handsets is a major issue because if the operator has to pay the major portion rather than wait a few years for new multimode handsets to saturate the market; the cost is far more than the transition of the RAN – multiply a few hundred dollars times several millions of users and it results in huge numbers. Another factor is marketing image. For instance, Verizon is motivated to maintain their image as the provider of the most advanced network not just to acquire new customers but also to retain those it already has. The loss of customers as they roll out LTE may be felt strongly, and will push them to provide a competitive multiple network or overlay plans, which may force down their pricing for 3G data service.

How the HSPA+ or LTE migration issue is framed make a difference: if framed from a more technical perspective it can be said that LTE does not yet have the proven capability to handle comparable voice calls. However, all studies and examples of early deployments show that voice capacity will be higher and better quality than for 2G-3G. But like every network that has ever been deployed, LTE has to be developed, debugged, deployed, tuned, and refined such that coverage is comparable to 3G and adequate QoS is maintained. If the appropriate funds and effort are expended, there is no roadblock in terms of the technology.


Some of the reluctance and concerns about problems are likely to stem from resistance to change. It is good to look back just a couple years ago and compare what major suppliers and operators were then saying about the prospects for WiMAX and LTE technology - many said that these were inferior or had no advantages over HSPA or EVDO. Since then, AT&T and Verizon have acquired spectrum at a premium cost to deploy LTE and other operators have announced commitments. The tone has definitely changed although nothing much has changed in terms of the technology of these systems except the natural process of development. AT&T is a prime example of this thought process: its director of networks recently said that although he considers LTE as a more capable technology platform, the company will still go ahead with enhancements to its 3G network, and recently gave details of initial upgrade plans to HSPA+. The reason for going ahead with upgrades rather than converting to LTE are as I have previously outlined: the move to LTE would be disruptive to current handset users and costly for AT&T.


For more information you can contact the author at robert@maravedis-bwa.com

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