Shrinking 3G cells and the need for 4G

Don Sambandaraksa

Shrinking 3G cells and the need for 4G

July 13, 2012

Oh, the irony. Just as the 3G smartphone and tablet revolution is taking off, some industry observers are saying that the CDMA technology is creaking on its last legs, and everyone is waiting for 4G OFDMA to solve the problem rather than invest more in existing 3G networks.

The issue here is cell breathing. Unlike a standard 2G cell which is capacity constrained but has a consistent radius of roughly 33 km (depending on tilt), CDMA sees its cells shrink or breathe as more users come online. The more users there are, the smaller the cells are because of interference. Hence capacity and network planning have to be conducted hand-in-hand.

The problem is that with today’s urbanites all having smartphones and tablets and uploading pictures of everything they eat, the range of a base station can be as little as a few hundred metres in densely populated areas such as trendy restaurants and pubs. So says Laurent Perche, formerly of Alcatel-Lucent but now representing Edgecast in the region.

Perche said that he has observed the European telcos playing a waiting game, not even trying to add pico cells (partially due to red-tape but also due to cost) and hoping that LTE and its OFDMA technology will come along soon enough to solve the problem. Luckily, the cells are usually placed near concentrations of people so that shrinkage does not cut the bulk of users off the cell edge. Femtocells and Wi-Fi hand-off are solutions many are adopting today instead as a stop-gap measure.

However, Bangkok is a different kettle of fish entirely. Perche said that Bangkok is unique in being a metropolis connected almost exclusively with fiber. In any other city, cells would be connected with a combination of fiber trunks and microwave branches. The consequence of these two would mean a much higher cost to roll-out a proper 3G network than in any other country, and thus should arguably mean a lower licence fee.

This has already manifested itself in some odd business plans. TrueMove gave the Bangkok metropolitan administration 20,000 Wi-Fi access points for free public W-iFi use, but it has been suggested that the real reason was not altruistic kindness from the bottom of its corporate heart, but rather as an excuse to gain easy access to lay down fiber for its 3G network.

Back in 2010, I was at focus group by the Thai regulator listening to Intel talk about how great Wimax was and how it was far superior to 3G technologies for broadband wireless access.

“In order to get full speed on an dual-channel HSPA+ (42 Mbps), network, you would not only have to sit next to a cell site, but do so at 4am in the morning when everyone was asleep,” said Kelvin Lim, Intel’s Wimax MD.

Intel’s argument, now only a historical footnote, was that CDMA technology’s achilles heel was susceptibility to interference, which manifested itself in cell breathing. The company asserted that while speeds of 42 Mbps are possible in labs, a real-world sanity check would yield nothing near the sort with a large number of users.

Years later, it seems that Intel’s and Wimax’s argument has been proven true, if posthumously. Operators are indeed looking to OFDMA technologies to solve the heavy investment due to cell breathing problems, only they are looking to LTE and not Wimax.

One wonders if the industry would have been better served had Wimax won. It is a valid question - would the savings in network costs rollout given a vibrant, healthy Wimax ecosystem been worth a technology platform shift compared to rolling out more and more, smaller and smaller 3G cells which are now costing many telcos an arm and a leg? Would telco bosses have acted differently two or three years ago if they knew then that in-town cell sites would shrink to only a few hundred metres because of the smartphone brigade?

Perhaps a bigger question was whether the industry, collectively, operated rationally; or if it was the lobbyists who fought a religious war rather than one based on the better technology.
 

Thumbail image from server side store: 
Don Sambandaraksa


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