There was a certain consternation at this week’s Small Cells World Summit when a speaker from NTT DoCoMo showed off a roadmap including not just LTE-Advanced, but ‘LTE-B’ and ‘LTE-C’. Of course industry bodies are already starting to look at 3GPP Release 11 and beyond, and DoCoMo is well known for being in the vanguard of any new RAN standards, but with carriers just wrestling with the implications of introducing LTE-A from 2013, few had the appetite to be considering future upgrades just yet. However, the presentation emphasized, once again, how the big Asian operators are increasingly setting the agenda for LTE, in terms of technology advances and commercial models. The approaches of cellcos like DoCoMo and Korea’s SKT reveal a more profound rethink of RAN norms than has yet been seen in the west, and the region’s leaders are leading the way in key trends like metrocells and LTE roaming.
Last week, SKT outlined the next stage of its 4G plans, which are sufficiently radical to be dubbed ‘LTE 2.0′. Like some US frontrunners like Verizon, the Korean mobile leader plans to introduce voice over LTE and LTE-Advanced next year but it has more dramatic changes to come too. It says it is already the world’s second largest LTE provider after Verizon, with 3.4m customers just a year after turning on its network in July 2011. It raised its forecast for its LTE base at the end of this year to 7m, from a previous estimate of 6m, and plans to achieve 99% population coverage this month.
Among the techniques the operator is pioneering are multicarrier (MC) technology. It will be the first carrier in the world to do this, enabling its network to harness its 800MHz spectrum and the 1.8GHz frequencies it acquired last year. This will double its spectrum for LTE services to 40MHz. SK Telecom kicked off an MC pilot in the Gangnam Station area at the end of May and will cover the whole Seoul area in 2012 and 23 other major cities by early 2013.
The company also plans the world’s first commercialization of a Hybrid Network Integrated Solution (HIS), which enables simultaneous use of LTE and Wi-Fi networks, in the fourth quarter of this year. This promises data rates of up to 127Mbps (LTE 75Mbps + Wi-Fi 52Mbps), which is 70% faster than the current LTE network, says SKT.
SKT will also commercialize one of the most important features of LTE-A, carrier aggregation, at an early stage (in the second half of next year). This will be important in operators’ most important quest, to be able to harness any spectrum they can access more efficiently to boost capacity. CA can double data speed by using two different bands, and SKT hopes to achieve peak download rates of 150Mbps by combining the speeds of its two frequencies.
Of course, its trade-off for being so advanced in terms of boosting LTE capabilities is that it will often be using proprietary approaches, since standards in areas like integrated carrier Wi-Fi are not finalized, and that is likely to increase its costs, and its reliance on its key suppliers. DoCoMo famously went commercial with W-CDMA ahead of any other operator, with a semi-proprietary implementation called FOMA, which gave it a headstart in Japan as well as a high degree of influence in standards bodies, patent holdings and the cellco community in general. However, it admitted it would not take the same approach in LTE, despite a very advanced program of R&D and trials, because it had reduced its handset choices, raised its capex costs and enforced a complicated migration to fully standard 3G later on.
More conventionally, it will deploy VoLTE in the third quarter of 2012. This will not just enable IP-based, carrier quality voice on 4G, eliminating the need for fallback to legacy networks, but will also add enhanced features such as better connection speeds. SKT will support HD Voice too. It has also added Rich Communications Suite (RCS) services to its to-do list. RCS supports rich IP-based services for messaging, voice and other core cellco offerings and has been pioneered, in a commercial sense, in Europe, particularly at Telefonica.
In topology terms, SKT and DoCoMo both believe radical new approaches to network design are essential to deliver the full benefits of LTE, and have made major commitments to dense zones of small cells, to boost capacity and move quickly to a fully integrated HetNet. SKT launched a commercial LTE femtocell earlier this month. Like China Mobile, it is also a supporter of a cloud-based approach to managing all those small cells and allocating resources between them. It has deployed a technology called Advanced-Scan (Smart Cloud Access Network), which uses virtualization to deliver four times better call quality at the cell edge, says the operator.
The effective deployment of small cells and HetNet is a key theme of operators’ LTE plans, because these techniques will enable them to make more of that scarce resource, spectrum. Their other main 4G headaches, roaming, is also a result of the race for spectrum capacity, since carriers are using almost any frequency they can get hold of, raising the prospect of hugely complicated device variations to support all the possible combinations. But as some operators move on from LTE trials and localized roll-outs to mainstream deployments, issues of roaming are becoming critical, especially given the wide range of bands in which cellcos are supporting 4G.
Here, the Asian firms are also leading the way. The regional operator group, Conexus Mobile Alliance, has revealed plans to encourage roaming between its members and to devise a unified approach.
Conexus members with live LTE networks include NTT DoCoMo in Japan, Korea Telecom and Hutchison Hong Kong. Other partners, including Singapore’s StarHub and the Philippines’ Smart are currently readying their networks for LTE.
The other participants in the group are further behind on 4G but will eventually benefit from a common roaming platform, which should simplify roll-out of interoperable services. Those members are Indonesia’s Indosat, Taiwan’s FarEasTone, Vietnam’s Vinaphone, Thailand’s TrueMove and India’s BSNL and MTNL. And Conexus has associations with other carriers from beyond the region, notably Vodafone.
Earlier this month, Hong Kong’s CSL and Korea’s SKT said they would offer the world’s first international LTE roaming service, between their two networks, from July.
But back to more futuristic visions of the network ‘ what comes next after LTE has exhausted most of the alphabet? Earlier this month, the 3GPP hosted a special meeting to discuss the possible requirements for the RAN as far as 10 years out. Topics included extensions of work on new architectures such as Cloud-RAN, which are expected to become commercial at the LTE-A stage but could be developed much further, given future advances in antenna and modulation schemes.