Huawei TDD LTE demo aboard the Shanghai MagLev train

, posted: 28-May-2010 18:02

IMG_1535I spent almost a week in Shanghai recently, courtesy of Huawei, the Chinese telco and network giant. There was lots to see, not at least the Shanghai World Expo 2010 which I covered for Wired, the well-preserved city itself and the public transport system that's excellent with underground trains, buses and Volkswagen taxis. Depending on who you ask, there are between 19 to 22 million people in Shanghai and trust me, it's a big place.

Huawei showed their new Shanghai digs and talked about a bunch of stuff, including the 3GPP Long Term Evolution or LTE standard for mobile phones and data. LTE promises at least 100Mbit/s peak downloads and 50Mbit/s peak uploads, and latency that's below 10ms - pretty fantastic figures for cellular broadband.

The variant used in China is TDD or Time Division Duplex but according to Huawei, their kit can do FDD or Frequency Division Duplex with just a software setting change.

The company took us through a room full of LTE gear, including the home router above, very fetching in red. Whether or not it was a working sample I don't know, but it did have electronics inside (I didn't prise it open so as not to upset my hosts).

IMG_1536This panel shows that Huawei thinks it will be able to hit 1.2Gbit/s with wireless in just a few years time, by using different modulation schemes, multiple aerials and other clever technologies to squeeze more out of existing spectrum.

For now though, I was curious to see how fast the existing LTE trial could go, and Huawei arranged a demo, set aboard the Shanghai MagLev monorail that runs between the metropolis and its Pudong airport.

As the name implies, the MagLev train  levitates on a mIMG_1560agnetic field and hits 431kph during the seven minute journey to the airport. Huawei and its techies said that LTE can keep a lock on the signal even at such high speed and still transmit data, which is most impressive.
Here's Luke Coleman, Huawei's media relations manager and former editor of Commsday Australia holding up the 4G USB stick to be used for the speed trial, and the laptop to plug it into - all pretty normal looking gear:
IMG_1571 IMG_1576
And off we go. at just under 200kph, we're downloading at 30Mbit/s on average. Huawei's LTE set up uses 20MHz of 2.6GHz spectrum. Unfortunately, I forgot to check what the latency was on the connection, to see if it was as low as the promised 10ms or better.


You didn't notice the speed much onboard the train, except for when another one passed with a bang due to the air pressure. At around 400kph, the LTE modem that the techie was holding next to the window lost synch with the base station and couldn't re-train on the signal again.

Luke from Huawei clarified that what actually happened was that the LTE network finishes halfway down the track - hence the lost signal.

Meanwhile, we continued accelerating until we hit that max speed of 431kph:




Again, you didn't really notice the speed onboard the train, but if you looked out of the window, Shanghai's suburbs were just a blur.

Overall, a pretty impressive demo although I expected a little faster download performance at standstill. I'm sure the technology will improve as time goes on though.

Other related posts:
TDD vs FDD for LTE
Apropos that new Telecom logo
Pipe Networks signs PPC-1 MoU: Sydney-Guam cable to go ahead

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