Verizon‘s IMS deployment, to support its LTE rollout with all-IP services, is just about the most advanced project of its kind in the world, and its “big bang” approach is closely watched by more cautious cellcos elsewhere. But the outages have raised questions over whether the carrier should be moving so quickly, and whether its technology is fully ready for the commercial big time.
While IMS is fairly well established, there are few comprehensive commercial deployments and none, apart from Verizon's, in an LTE network. In April, the first and most serious outage was traced back to a software bug in a network element of the IMS core, triggered by heavy signalling and rapidly spreading throughout the system. (Another early LTE deployer, Telenor of Norway, suffered an 18-hour outage which was also caused by a signalling overload earlier in the year). Meanwhile, a December 7 outage was caused by the failure of a back-up communications database. The two late December incidents were triggered by different IMS elements not responding or communicating properly.
In an interview with GigaOM, Verizon Wireless‘s VP of network engineering, Mike Haberman, said: “being the pioneers, we‘re going to experience some growing pains. These issues we‘ve been experiencing are certainly regrettable but they were unforeseeable.” In other words, Verizon is discovering many of the downsides of LTE on behalf of its more cautious peers – and taking the flak for them too.
Haberman said that once each IMS problem has been fixed, it has never recurred, but this points to a series of bugs, and to the complexity of a huge platform involving many elements from a range of vendors (notably Alcatel-Lucent, Nokia Siemens, Acme Packet and Tekelec). Haberman is putting various safeguards in place against further glitches, notably geographically segmenting the LTE network, so that a problem can be isolated to a particular region.
He is also upgrading the signalling infrastructure to handle the storms better, committing to the new Diameter signal routing platform, which replaces point-to-point communications between servers with multipath routing. Tekelec signed the most prominent Diameter contract to date in the 4G world in August, after Verizon's initial signalling-related outage.
SK Telecom’s HetNet
Another operator looking to ride on the LTE cutting edge this year is SK Telecom of Korea, which has announced one of the first wide-scale deployments based on the voguish, but largely untried, HetNet concept.
HetNet increases capacity and reliability by implementing multiple layers of cells, often in different bands and potentially supporting different technologies in parallel (3G, LTE and/or Wi-Fi, which in turn rides on the spread of multimode devices and femtocells). Carriers are highly interested in the idea and deployments are likely to go mainstream from 2013-14, but SKT is taking the risk of adopting this approach before it is mature, in order to stay ahead of rivals in one of the world‘s most sophisticated and demanding mobile and broadband markets.
multinetwork strategy
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SKT promises the world‘s first smartphone to support HetNet – not just the ability to move between the different networks but to harness the sum of their speeds and capacity. All its new smartphones will support the new approach from the start of 2013 and the cellco aims to push for the standardization of its Heterogeneous Network Integration Solution through groups including 3GPP and the ITU.
SKT has also developed a femtocell which supports LTE and Wi-Fi simultaneously. These will be used to boost service quality and as a step towards the HetNet, in the 84 cities where it plans to have LTE up and running by April this year.
KT is also taking innovative approaches as it adds LTE to its 3W program. Although it was the third carrier to go live with LTE, after SKT and UPlus, it will reach 90% of the population by April. It was initially delayed by regulatory hitches in its bid to shut down the 2G network in its 1.8GHz spectrum, in order to use this for LTE, but permission was finally obtained during the holiday period. The new network makes heavy use of small cells and “virtual” or software programmable base stations (a platform KT calls LTE Warp), again indicating how the Korean operators – like their counterparts in Japan and China - are pioneering new approaches to network design, such as cloud RAN and HetNet.
By contrast, early movers in the US and Europe are tending to build their first 4G networks conventionally and aim to introduce the new topologies as data demand requires, in phase two, and often in tandem with an LTE-Advanced upgrade.
Latest LTE deployments
* Alcatel-Lucent is supplying the Saudi Telecom Company (STC) with an LTE network, taking its total of LTE contracts beyond 20, plus over 70 trials. STC will be the first in the kingdom to launch major commercial LTE services to cover 11 key cities in the first phase. Through its ngConnect Program, the vendor will also help its customer to build an ecosystem of partners for content, applications and services.
* Hungary has gained its first LTE services, initially in capital Budapest, rolled out by the venture of T-Mobile Hungary and Magyar Telekom. The service was launched across 10 districts of the city after the operator carried out a three-month network testing phase.
* At least half a million base stations will be installed or upgraded for TD-LTE by the end of 2016, according to predictions by ABI Research. “It was only two years ago that nearly every Wimax operator, including operators with unpaired TDD frequency spectrum, was planning to deploy Wimax 2,” commented practice director Aditya Kaul. “Today, almost all of them have switched plans and are deploying TD-LTE” (except in fixed wireless or 3.5GHz scenarios). TD-LTE commercial services have been launched so far in Brazil, Japan, Poland, Saudi Arabia and other countries and roll-outs are underway in Australia and Scandinavia, and planned in China, the US and India. China Mobile announced plans last month to install an additional 10,000 to 20,000 TD-LTE base stations in 2012 as part of its huge testing program, and perhaps another 60,000 in 2013.
* After various false starts, Russian operator Yota has gone live with the country‘s first LTE network, the first step in a planned wholesale system to support 4G services for the main operators. Yota (the brand name of Scartel), has switched on its LTE system in Russia‘s third largest city, Novosibirsk in Siberia. The first phase of Russia‘s progress towards LTE revolves around a plan, announced earlier this year, for the three main cellcos (VimpelCom, MTS and Megafon) plus fixed line giant Rostelecom, to use Yota‘s network on a wholesale basis. But various complications have arisen and while Megafon and Rostelecom were recently reported to have finalized their deals with Yota, the other two cellcos seem to be hesitating, possibly because they will be forced to give up valuable, and active, frequencies in Moscow and St Petersburg in return for their stake in the Yota venture. Both MTS and VimpelCom also plan to expand their activities around Novosibirsk.
* Hong Kong‘s regulator OFTA has issued a consultation paper on its proposals for releasing a total of 50MHz of paired spectrum in the 2500-MHz to 2690-MHz band, including 15MHz left over from its 2009 LTE auction. It aims to auction five slots, each with a bandwidth of 2×5MHz, on a technology neutral basis, with no spectrum cap, under 15-year licences.
* Armenian mobile operator VivaCell-MTS has launched the country‘s first commercial LTE network, initially in the center of Yerevan. Further expansion to Gyumri and Vanadzor and other regional cities is planned. The operator has 40MHz of spectrum in Yerevan (2.5GHz) and the regions (2.6GHz).
*Two mobile operators in Bahrain have progressed their LTE plans. STC unit Viva Bahrain has launched a small scale network with coverage of the “Bahrain City Center” retail and leisure complex in central Manama. Meanwhile, Batelco has completed an LTE trial at its Hamala headquarters, working with Ericsson. Viva completed a nationwide roll-out of DC-HSPA+ in November 2011. The country‘s earliest LTE triallist, Zain Bahrain, is yet to announce a commercial launch date, though it has completed tests with Nokia Siemens.
* Viva's Bahrain LTE launch follows its sister cellco in Kuwait launching a commercial network based on the 4G technology in the final week of December 2011.