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 its image as the provider of the most advanced network, not just to acquire new customers but also to retain those it already has.
How the HSPA+ or LTE migration issue is framed makes 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.
Robert Syputa is a senior analyst and partner at analyst firm Maravedis. Contact Robert at [email protected]. Maravedis is a leading analyst firm focusing on disruptive technologies including smart networks using WiMAX, IEEE, and 3GPP/LTE. maravedis-bwa.com