Hands on with South Korea's cutting-edge mobile WiMax service

IDG News Service - SEOUL -- It has been a year since a mobile WiMax service was launched in Seoul and one of the world's most wired cities became one of the most wireless.

The service is based on WiBro, a South Korean system that has become a part of the 802.16e Mobile WiMax standard. Whereas mobile WiMax encompasses three frequency bands and several signal bandwidths, WiBro covers a subset of these and is limited to 2.3 GHz and a bandwith of 8.75 MHz per channel.

To mark the launch of its WiBro service last year, KT Corp., the former state-run telecommunications carrier, took journalists on a trip around Seoul to try out the service in a WiMax-equipped bus. The reporters came away impressed, able to watch streaming Internet video while surfing the Web and videoconferencing while driving down the street.

But what's the reality a year later? Last week, I returned to Seoul to test the service again, this time outside the controlled environment of a promotional bus ride. Seoul is among the first cities in the world to have mobile WiMax, so the results provide an indication of what the rest of the world can look forward to.

I accessed the service while on the subway, in a bus and sitting in a coffee shop, and the results were as impressive as they were in last year's staged demonstration.

This was especially true on the subway. Riding the No. 2 line from Samseong Station to City Hall, the journey has both underground and overground sections. It connects the Teheran Valley high-tech district in the south, crosses the Han River and ends in the heart of Seoul's business and media district.

Throughout the 30-minute journey, I did not lose the signal once, although the speed did fluctuate somewhat. It would often drop when the train moved out of a station and increase again when it arrived at the next stop.

Web and e-mail access worked so well that I decided to try something a little more demanding and accessed streaming video news clips from the Yahoo Japan portal. The clips are encoded at 300Kbit/sec. and played without any problem, even while the train was in motion.

Equally surprising was that my little experiment did not draw the attention of the passengers sitting next to me. In a country where most high-end cell phones have TV reception, watching streaming video on the train doesn't seem to impress anybody.

I also accessed an FTP site in the U.S. from the train and started to download a 40MB video file. The software indicated a download speed of up to 660Kbit/sec. in stations and about 320Kbit/sec. when the train was in motion.

Reprinted with permission from

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