Market Spotlight: LTE TDD

The commercialization of Long Term Evolution (LTE) finally started to happen in 2010 with the launch of a number of networks across the globe.

There are now 11 commercial LTE networks: five in Europe, two in the U.S. and four in Asia-Pacific, according to a recent whitepaper written by Heavy Reading Senior Consultant Berge Ayvazian. (See Where in the World Is LTE?)

All of these early LTE networks are based on the frequency division duplex (FDD) variant of the next-generation mobile technology. But now attention is turning to Long Term Evolution Time Division Duplex (LTE TDD), and in the next two years there will be more activity around the TDD version of LTE.

Indeed, the market could see the first LTE TDD launch very soon, and the location could come as a surprise. While the world's largest operator by subscribers, China Mobile Communications Corp. , is driving the pace of LTE TDD development, it looks like the Chinese operator will be pipped to the post in launching the world’s first commercial LTE TDD network. Polish startup Aero2 is set to launch a network in early 2011 after the mobile broadband service provider awarded an LTE TDD contract to Huawei Technologies Co. Ltd. . (See Aero2 Picks Huawei for LTE TDD.)

What's driving LTE TDD?
China Mobile is the driving force behind LTE TDD. The operator's network trials along with work at the 3rd Generation Partnership Project (3GPP) standards body to unify the FDD and TDD variants have spurred the development of this alternative version of LTE.

In addition, several other factors are driving LTE TDD: the recent broadband wireless access (BWA) auctions as well as the availability of existing licenses in the 2.3 GHz and 2.6 GHz bands in Asia-Pacific, Europe, the Middle East and Africa, and the Americas; WiMax service providers' increasing interest in LTE TDD as a way to evolve their networks; and the interest by operators, particularly in Western Europe and North America, in using LTE TDD as a way to increase network capacity and offload data traffic by using FDD for their macro networks and TDD for picocells. (See SK Dropping WiMax for LTE and Sprint Ready to Leapfrog to Multi-Mode.)

Such developments have led analysts to predict strong subscriber numbers in the coming few years. According to Heavy Reading and Pyramid Research figures, LTE TDD subscribers worldwide are forecast to increase from 6 million in 2011 to nearly 158 million in 2015 driven by services from operators in the Asia-Pacific and North American regions. This compares to LTE FDD subscriber forecasts of 12 million in 2011 and more than 264 million in 2015, driven largely by operators in Western Europe, Japan and the U.S.

First and foremost in stimulating the LTE TDD market are the trials being carried out by China Mobile, which calls the technology TD-LTE in order to be consistent with its TD-SCDMA 3G network. (See China Mobile Opens Up on LTE TDD Trials .)

“LTE TDD is almost entirely driven by China Mobile,” says Heavy Reading's Ayvazian. “Everything else is kind of the next stage.”

According to Ayvazian, TD-SCDMA was not as successful as China Mobile had wished, and the company is now pinning its hopes on greater global acceptance of LTE TDD: “They don’t want their 4G network to be an island too,” he notes. “It’s very important for China Mobile that operators will adopt the same solution and will have roaming capabilities. The company just wants to be part of an ecosystem that is worldwide.”

After China, according to Ayvazian, India is expected to be the next market for LTE TDD. The Indian government has issued broadband wireless access (BWA) licenses in the 2.3GHz band and it’s expected that operators, particularly Reliance Industries Ltd. (RIL) , will use the spectrum for LTE TDD with services possible this year (See Analyst: LTE TDD Will Reach India in 2011 and Reliance Gives Impetus to LTE TDD in India.)

According to Heavy Reading Senior Analyst Gabriel Brown, both China and India are set to launch LTE TDD in 2.3GHz spectrum in 2011, with Indonesia also possibly following in their footsteps.

“These are the first, second and fourth most populous countries,” Brown observes. “This is enough to get good economies of scale.”

Size matters
As with any new wireless technology, size matters and economies of scale will be crucial to the success of both FDD and TDD variants of LTE. To that end, vendors say they can now support both TDD and FDD on the same base-station platforms.

Even so, the general view is that operators will adopt single-mode LTE for the time being.

A Heavy Reading survey of mobile operators in 2010 revealed “a cautious and phased effort to leverage FDD and TDD spectrum in LTE network deployments planned over the next five years.”

According to the survey, 19 percent of operators surveyed plan to lead with an LTE TDD network; another 12 percent plan both FDD and TDD LTE deployments within three years; 45 percent of respondents will lead with FDD with potential to add TDD in the long/medium term; and 25 percent of respondents plan to lead with FDD and are unlikely to use TDD.

For most vendors, the most important dual- or multi-mode requirement for now is the ability to run 3G technologies concurrently with one form of LTE or another. The requirements will vary by region. Huawei, for one, says the support of WiMax and LTE TDD is more important for its business right now.

Where it gets more complicated is on the devices side, says Brown. LTE supports multiple frequencies -- and this will be an issue for both TDD and FDD devices. Qualcomm Inc. (Nasdaq: QCOM) estimates that there are around 20 different bands that will need to be supported with the addition of LTE; it will not be possible to support all of them on one device. (See Apple to Support China Mobile's LTE?)

Chipset makers such as Qualcomm, ST-Ericsson and Sequans Communications have all developed baseband support for both TDD and FDD on one chipset, to enable OEMs to configure their devices in whichever way they require. “The problem is the radio part,” says Brown. “It’s the plethora of frequencies that will be difficult.”

Brown believes this will lead to different geographical profiles for devices, whereby 2G and 3G technologies will continue to be required to enable voice and data roaming on a global basis.

So how ready are network equipment suppliers to meet the demand for LTE TDD and how are they positioning their products? Light Reading interviewed the following wireless infrastructure companies about their product plans and how they view the LTE TDD opportunity:

And for a perspective on the prospects of LTE TDD devices, Light Reading spoke with these chipset vendors:

On the following pages, each of these companies gives its view on the LTE TDD market and outlines its product development strategies.

Here's a hyperlinked list of contents:

— Anne Morris, freelance editor, special to Light Reading

Alcatel-Lucent is participating in more than 60 LTE trials worldwide, of which 11 so far have involved LTE TDD, including the trials with China Mobile, according to Danny Locklear, the company's senior director of global LTE solutions.

“LTE TDD is growing in momentum as frequencies become available,” Locklear says. “Sixteen or seventeen countries have TDD spectrum, and we are involved everywhere that they have spectrum for LTE TDD.”

AlcaLu says it can fundamentally support both FDD and TDD variants of LTE; its 9926 digital 2U Node B base station is designed to support 3G and both LTE variants. However, the company currently sees operators asking for one or the other, and not both together.

“There is not a large pool looking to do both -- certainly not initially,” Locklear says. “We can support dual-mode FDD/TDD today, but we are driven by demand and we see no demand from operators for it right now.”

When pressed further on the dual-mode aspect of LTE, Locklear concedes that Alcatel-Lucent is not currently shipping base stations that can support both, but will be in a position to do so in a month’s time with a new software release.

“It’s a fair general statement to say that Europe and the U.S. will drive dual-mode demand,” he adds. “The demand today is around either TDD or FDD.”

Along with Ericsson and Samsung Corp. , Alcatel-Lucent is also involved in Sprint Corp. (NYSE: S)'s network modernization project, which will involve the construction of a multi-mode 3G/WiMax network with eventual support for LTE. (See Clearwire Paves Way for LTE in US and Sprint Ready to Leapfrog to Multi-Mode.)

Heavy Reading's Ayvazian says this is a large deal that could drive the direction of the market, whereby spectrum assets will determine the LTE variant that Sprint is likely to support. In March last year, both Sprint and Clearwire LLC (Nasdaq: CLWR) asked the 3GPP standards body to start work on specs that would allow LTE TDD to be deployed in the US in the 2.6GHz spectrum, which is now used for WiMax. (See Clearwire Paves Way for LTE in US.)

Next Page: Ericsson

For Ericsson, LTE TDD is a global standard and represents a strong alternative for operators with unpaired spectrum.

The company’s key first milestone with LTE TDD will be the deployment of its end-to-end system with China Mobile, according to Ulf Ewaldsson, vice president and head of product area radio at Ericsson. The vendor already has been busy in China. Last July in Shanghai, ST-Ericsson and Ericsson showcased LTE TDD interoperability testing between a chipset from ST-Ericsson and mobile network equipment from Ericsson.

Ewaldsson doesn’t like talking about numbers of trials: “It’s becoming silly,” he says, observing that claims of LTE trials by vendors don’t really add up.

Nevertheless, Ericsson has been involved in LTE TDD trials in India with Reliance; in China with China Mobile, where the Swedish vendor is working in close cooperation with Datang Telecom Technology Co. Ltd. to develop advanced TDD solutions for both China and the rest of the world; and in Ireland together with regulator Commission for Communications Regulation (ComReg) . The vendor has also showcased the technology in Thailand.

Ewaldsson says that Ericsson is able to build LTE networks in all different bands and standards, based on the RBS 6000 multi-standard base stations that support GSM, EDGE, WCDMA, HSPA and LTE.

“This gives us full flexibility,” says Ewaldsson, also claiming that Ericsson has the shortest lead times for adding new radios to deal with additional frequency bands.

Ewaldsson concurs with the general view that it will be a lot more difficult to adapt devices to the plethora of LTE frequencies. But he believes that LTE will bring a more diverse terminal market, ranging from PCs through to tablets, smartphones and game consoles. “Some devices won’t need to roam,” he comments, and notes that 3G and GSM will continue to be used for global roaming purposes.

Next Page: Huawei

Huawei is slightly ahead of the curve on LTE TDD in terms of commercial deployments: It has won the contract for what is set to be the world’s first commercial LTE TDD network.

In November last year the Chinese equipment manufacturer said it had won the frame contract to deploy an LTE TDD network for new Polish mobile broadband operator Aero2, which holds spectrum in the 900MHz and 2.5GHz frequency bands. The network is expected to become operational in early 2011.

Interestingly, Huawei has also deployed an LTE FDD network in Poland, for Mobyland Sp. z o.o. , in the 1800MHz frequency band using dongles from IPWireless Inc. . What’s even more interesting is that Mobyland is a 100 percent-owned subsidiary of Aero2.

According to Xingang Lu, Huawei's vice president of CDMA/TDD/LTE product line, Huawei is pursuing a dual-mode approach to LTE TDD and FDD with its SingleRAN technology, but dual-mode cannot be supported as yet. Lu says dual-mode LTE will be enabled when operators demand it. For now, the most important combination for Huawei is WiMax and LTE TDD.

“We see this combination as more important right now: There are currently more than 500 WiMax operators, and WiMax is now not enough for them,” says Lu. “So we provide them with a way to move smoothly to LTE.”

Indeed, Huawei’s second commercial LTE TDD contract is a WiMax/LTE TDD deal with Etihad Etisalat Co. (Mobily) in Saudi Arabia. The vendor has a third commercial LTE TDD contract, but it says that it is not as yet in a position to reveal the name of its partner.

Lu says Huawei’s focus will be on the evolution of legacy WiMax services. The company can now support LTE TDD and WiMax, and in future will support both TDD and FDD variants of LTE as well as WiMax.

“But very few operators would use this scenario,” says Lu. “There is not really a need to have all three.”

Next Page: Nokia Siemens Networks

Nokia Siemens Networks says LTE TDD and LTE FDD are of equal importance to its future strategy and it is spending the same amount of development time on both variants.

According to Thorsten Robrecht, head of LTE product management at Nokia Siemens Networks, “We believe TDD represents a major part of the business over the next four years -- even though it is a little behind FDD.”

Robrecht says Nokia Siemens has carried out six LTE TDD trials so far, including trials in China, Japan and India.

“In China this is proceeding according to plan and this will be the biggest deployment this year. We have a 100 percent compliance rate in this market,” says Robrecht, referring to tests carried out at the Ministry of Industry and Information Technology (MIIT).

The company says it is able to support both variants of LTE on the same Flexi Base Station. Currently, the vendor is shipping WCDMA base stations with LTE FDD support, but will be able to add in TDD when this is required by operators. Robrecht comments that the hardware is exactly the same; it is at the software level that adjustments need to be made.

“Under 3GPP, TDD and FDD LTE are more than 90 percent identical -- so there are only small differences to make on top of this,” he adds. “We have our own matrix of where we think concurrent modes and combinations will be required. We see this as a different requirement in different parts of the world. How we release it will depend on the individual customer, and we cannot disclose our plans for competitive reasons.”

Robrecht did say he thinks concurrent use of TDD and FDD LTE could happen in 2012 or 2013 in regions such as Europe, where operators are interested in TDD as a way to increase the available capacity on their networks. He says Nokia Siemens Networks is currently unable to talk about WiMax support because of the ongoing negotiations over its acquisition of Motorola's wireless infrastructure business, which the company agreed to purchase in July 2010. But he notes that WiMax does have a strong evolutionary path to LTE TDD. (See NSN to Buy Moto's Wireless Biz for $1.2B .)

He adds that LTE TDD dongles should be in the market in the first half of this year, but says it’s not yet clear when dual-mode devices will be available.

Next Page: ZTE

Chinese equipment manufacturer ZTE says it deployed more than 10 LTE TDD trial networks in seven countries in 2010, including the China Mobile trials in six Chinese cities, a trial in India in November 2010, and three trials in Europe.

According to Xu Ruixue, TDD marketing director at ZTE, the company expects to increase its number of LTE TDD trials to around 20 in 2011, although she notes that the number could increase beyond this level.

Xu says ZTE is expecting China Mobile to launch pre-commercial services in the third quarter of 2011, with mass-market services likely in 2012.

ZTE claims to have been the first vendor to have got involved with LTE TDD and has worked with China Mobile on evolving the operator’s network from TD-SCDMA to LTE TDD.

Like Huawei, ZTE also supports the evolution of WiMax networks to LTE TDD, and in October last year it launched the ZXMBW R9110 WiMax/TD-LTE dual-mode Remote Radio Unit.

ZTE currently has separate departments for TDD and FDD, but Xu says the vendor is now starting work on how to network the two LTE variants. “It depends on what operators want,” Xu observes. “All markets are different. Most operators are now watching China Mobile.”

Xu notes that FDD has had a head start on TDD, but she said it’s important to note that the countries with the biggest populations are launching LTE TDD. “I’m not sure which will be the bigger technology in the longer term,” she adds.

Next Page: ST-Ericsson

If the network equipment vendors believe they are largely ready with platforms to support both variants of LTE, with configurations dependent on the requirements of network operators, the situation is a great deal more complex for the device manufacturers due to the multiple frequency bands that will be supported in future.Indeed, Ericsson’s Ulf Ewaldsson says that spectrum from 400MHz to 4GHz “will be interesting for mobile communications."

Bjorn Ekelund, from the CTO office of ST-Ericsson, says the chipmaker has worked closely with China Mobile on TD-LTE and showcased Nokia and Quanta Computer Inc. devices at the Shanghai Expo last year. Its second main public trial was with Reliance and Ericsson in India last November.

As things stand, ST-Ericsson supports both variants of LTE in its M700 and M720 platforms. “This year we will support both LTE modes in the same electronics,” says Ekelund. “But for now, you can build either TDD or FDD devices but not both in one device. It’s very difficult to combine them in the RF; it gets complicated.”

ST-Ericsson’s view is that in the early years of LTE, an operator will most likely use either TDD (like China Mobile) or FDD (like Vodafone Group plc (NYSE: VOD) and Verizon Wireless ), so a device will not have to work in a multimode environment in the same network doing handover between TDD and FDD.

“A single-mode device will be first on the market -- and it also needs to be multimode with legacy technology such as WCDMA,” says Ekelund. “We first need to be successful with single-mode LTE and master all of the variants. I don’t believe there will be TDD/FDD devices this year.”

The company notes that its customers, the OEMs, might include TDD in an FDD device and vice versa, but only for roaming purposes.

“We also see mobile device manufacturers strive to develop global products, which can be sold in many regions, for many operators, and then it's a great strength to support both TDD and FDD in the same chipset,” ST-Ericsson added in comments emailed to Light Reading. “From our point of view we are well prepared to meet the demands from OEMs and operators. Our new generation of modems will be available this year and will support multimode (LTE TDD and LTE FDD, HSPA+, EDGE and TD-SCDMA) as well as all frequency bands required by our customers.”

Next Page: Qualcomm

Some of the mobile network equipment vendors have commented that Qualcomm is late to the party with a chipset that supports LTE TDD.

“Some said we were late with LTE FDD,” quips Steve Brown, senior director of RF product management at Qualcomm CDMA Technologies (QCT).

Brown gave assurances that LTE TDD is well underway at the company, and said commercial chips should be available in the second half of 2011. The company has also said its Mobile Station Modem MSM8960 Snapdragon chipset will start sampling this year and will support 3G and LTE smartphones.

Like ST-Ericsson, the San Diego-based company demonstrated LTE TDD products at the Shanghai Expo based on its Mobile Data Modem MDM9200 solution in the 2.3GHz band. The company said it would then carry out trials with various operators around the world using the MDM9200 and MDM9600 solutions, with a commitment to help OEMs bring LTE TDD products to market in 2011.

Qualcomm has of course also been heavily involved with LTE TDD trials in India, where it also currently owns unpaired spectrum in the 2.3GHz band. (See Qualcomm Unveils LTE Plans for India, India's Billion-Dollar LTE Question and Qualcomm Updates on India Exit Plan.)

Again like St-Ericsson, Qualcomm can support 3G and both FDD and TDD variants of LTE on the chipset platforms, but sees the same challenges for devices with different radio frequencies and handover between TDD and FDD.

“We see up to 20 [radio-frequency] bands being available,” says Brown. “Incorporating up to seven or eight radio frequencies on one handset is a challenge.”

Indeed, different bands have been made available all over the world to support LTE TDD deployment: 2.6GHz and 2.3GHz in China, 2.5GHz in Japan, 2.3GHz in Russia, 2.3GHz in India, 2.6GHz in the U.S., and 1.9GHz in many European countries.

Senior Director of QCT Product Management Peter Carson, says Qualcomm sees its role as enabling as many options for OEMs as possible. He also agrees that LTE devices based on both TDD and FDD will most likely focus initially on a combination of frequency bands that will be targeted at one geographical region.

Brown adds that the LTE TDD market will be pretty fragmented at first in terms of markets and operators, which in turn will require different configurations of devices.

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