FEATURE TDLTE
collaboration to accelerate the develop- ment of TD-LTE devices. Specifically, the two companies agreed to work together to cultivate a device ecosystem that supports multi-mode, multi-band devices, based on successful TD-LTE trials and tests using commercially available/production-ready TD-LTE devices from numerous vendors. In terms of geographic deployment, India
is seen as another potential hotspot for TD- LTE deployment and, towards the end of 2010, Wireless Broadband Business Services Private Limited, one of Qualcomm’s Indian LTE venture entities, and infrastructure vendor Ericsson successfully demonstrated TD-LTE at 2.3GHz in an outdoor environ- ment. The demonstration streamed multiple high-definition live video feeds to a mobile van in the Gurgaon area, showing a seam- less hand-off between base stations while maintaining session continuity. The dem- onstration was carried out by using Radio Access Network (RAN) and Evolved Packet Core (EPC) solutions from Ericsson, and USB dongles based on Qualcomm’s MDM9x00 multimode chipset, which supports both LTE and 3G. While WiMAX was at one time seen as the most fitting technology for India, Indian Broadband Wireless Access (BWA) spectrum winner Aircel, backed by Malaysian inves- tor Maxis Communications, switched tack to TD-LTE rather than WiMAX, describing the former as a “more robust technology”. Throughout 2010, TD-LTE was also tested in Ireland by Ericsson using a test license is- sued by local regulator ComReg in the 2.3GHz band. While WiMAX/LTE player Clearwire,
On the LTE bus
During Mobile World Congress this year, MCI got to experience the maturity of TDD first hand, and was able to compare it to FDD on a test drive around Barcelona set up by China Mobile and Vodafone, using equipment supplied by Huawei and Nokia Siemens Networks. The trial consisted of two cells, one provided by each of the vendors, with each cell divided into four sectors: two TDD and two FDD. The spectrum available, pro- vided by Vodafone Spain, was 10MHz of 2.3GHz frequency for TDD and 2x10MHz of 2.6GHz frequency for FDD. The single mode dongles for the Huawei demo were both provided by Qualcomm, while for the NSN demo, the FDD card was contributed by Samsung. The drive test was focused on the end user experience and featured application usage based on different scenarios in order to show the basic performance of the
system and demonstrate how operators can overcome the difficulties of sending rich media to customers. We started off with a demonstration of 24 streams of video—each one showing different footage—mirrored across two widescreen displays, one connected via FDD
and the other by TDD. The video was driving about 23Mbps of throughput and Mark Atkinson, global head of NSN’s TDD LTE business, pointed out that at this point it’s the laptop that starts to become the bottleneck rather than the radio network. He also pointed out that HD video is currently the only user of high levels of bandwidth, as most apps can’t make use of the throughput available. Nevertheless, we also got to experience 20Mbps of streaming HD 3D video, as well as a live video feed taken from a camera on the bus, which was sent uplink over FDD and streamed back down over TDD, convincingly demonstrating a low latency of around 100ms at the cell edge, about 800m away from the cell site in rainy and foggy conditions. Co-operative mobile gaming across TDD and FDD demonstrated latencies of around 15-20ms, while video conferencing and IMS also got a look in during a three-way video call between the bus, a Vodafone site in Germany, and another in Barcelona, all backhauled by LTE-FDD at 2.6GHz.
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which operates in the US as a spin-off of Sprint, is also testing TD-LTE in Phoenix, Arizona, using kit from Huawei, Samsung, Beceem and others, in its 2.5GHz spectrum, to assay the co-existence of WiMAX with both FDD LTE and TDD LTE, to confirm the flexibility of its network. While all the major vendors are cutting themselves a slice of the TD-LTE pie, it would be unwise to discount China’s do- mestic champions. At the end of March, ZTE and Swedish operator Hi3G, owned by Hutchison’s 3 Group, partnered to launch what they claim will be the world’s first LTE TDD/FDD dual mode network. The move is designed to give Hi3G some clout against its local rivals where it faces stiff competition, not least in Sweden from early adopter TeliaSonera, which launched the world’s first commercial LTE network in 2010. Hi3G owns 50MHz of spectrum in Sweden and 25MHz in Denmark and has tapped ZTE to upgrade its existing 3G networks as well as to deploy mobile broadband over the course of 2011, which will “introduce LTE technology with very high data speeds of up to 100Mbps.” Both TDD and FDD flavours of LTE will be deployed in the Hi3G rollout, which ZTE claims will be the first network in the world to use both technologies in dual mode.
ZTE is also involved in a trial of TD-LTE in Germany with KPN-owned E-Plus using the 2.6GHz spectrum acquired in spectrum auctions that concluded in May 2010. China Mobile will be working to support this trial, and probably many others, as the main flag
waver for TD-LTE. ZTE said earlier this year it had secured 18 contracts to build both trial and commercial TD-LTE networks in Europe, the former Soviet republics and Asia. Besides China, an estimated 20 plus
TD-LTE trial networks have been built in India, Europe, and North America, giving the “global standard” more credence, according to China Mobile. At the time of going to press, Huawei had been tapped up by Polish operator Aero2 to deploy a TD-LTE network with a view to a commercial launch hitting 25 per cent of the population and over 200 urban and rural communities in Poland by the end of 2012. The inauguration of the Global TD-LTE
Initiative, of which Aero2 is a founder will see a focus on creating value for stake- holders across the TD-LTE ecosystem to promote the fast development of the tech- nology and the convergence of LTE TDD and FDD modes to maximise the economies of scale, calling on the chip and device sec- tors to support both modes from day one in their products. “The mobile internet era will be the era of
TDD. The development of mobile broadband highlights the unique flexible advantage of TDD spectrum,” said Wang Jianzhou, chairman of China Mobile, at the launch of the initiative. “China Mobile has been committed to the converged development of LTE TDD and FDD, which will achieve the economy of scale and the wide support from global industry. With great effort from all partners, TD-LTE enters commercialisation and global deployment.” Clearly this is not just a Chinese technology. n
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