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LTE-Advanced is the future, but no rocket ship
| 26 января 2012 |
The 4G network standards approved last week by the ITU may improve the mobile data experience soon, even if consumers don't actually see the 100M bps mobile speed for which they were designed.
The International Telecommunication Union gave its seal of approval to the two new standards, LTE-Advanced and WirelessMAN-Advanced, at the ITU Radiocommunication Assembly in Geneva last Wednesday. WirelessMAN-Advanced, the second generation of WiMax, is not expected to be widely deployed. But LTE-Advanced, the next version of the Long-Term Evolution standard chosen by most carriers moving to 4G, could start improving mobile networks soon.What the ITU technically did last week was to certify the two network specifications as IMT-Advanced, or officially 4G (fourth generation). When it originally planned for 4G, the successor to the 3G technologies that started to be deployed early in the past decade, the ITU insisted the next-generation networks be able to deliver 100M bps (bits per second) downstream with high mobility and 1G bps from one location.
After the slower WiMax, LTE and even HSPA+ technologies started to be called 4G, the agency loosened its definition. But its goals for IMT-Advanced stayed in place.
Consumers shouldn't look for 100M bps when the first carriers start implementing LTE-Advanced, probably later this year. In most cases, it won't even bring a speed increase like the move from 3G to LTE did. But the new standard should improve the wireless experience, according to industry analysts.
The upgrade to LTE Advanced, which most carriers will do gradually, will basically help them add lanes to a highway, said analyst Monica Paolini of Senza Fili Consulting. Drivers don't necessarily go faster on a multilane highway, but the additional lanes are needed if more drivers want to go full speed in the future. "Capacity might not be an issue today, but it is going to become an issue pretty soon," she said.
The LTE-Advanced standard is actually made up of several components, of which service providers can use some or all, said analyst Peter Jarich of Current Analysis. These include aggregation of separate spectrum bands, better integration between small and large cells, the use of four or more antennas in a device, and relay devices at the edges of cells.
Jarich expects most service providers to start out with LTE-Advanced by combining frequencies and adding more antennas. So-called "carrier aggregation" allows an operator to build up a big chunk of spectrum virtually, out of frequencies spread around the spectrum band. LTE already uses MIMO (multiple-in, multiple-out) antenna systems, but only with two antennas per device. LTE-Advanced will allow for four or more antennas, potentially boosting speed and reliability. However, it's not clear how many antennas may ultimately fit in a smartphone, Jarich said.
Heterogeneous networking is another promising tool in the new standard, Jarich said. It includes mechanisms to make conventional macro cells work better with the smaller cells now being developed to better serve crowded and indoor areas. For example, it could prevent subscribers from being bounced back and forth between large and small cells because of small differences in power between them, he said.
Though all these features may add up to the potential for a true 100M bps mobile service, it's not clear that carriers could build one or that subscribers even need it. Analyst Phil Marshall of Tolaga Research estimated it would take 50MHz of spectrum to deliver that much speed. To put that in perspective, Verizon Wireless uses just 10MHz each for its upstream and downstream channels today.
With most mobile applications, users couldn't even see any additional speed beyond 20M bps, said Chetan Sharma, of Chetan Sharma Consulting.
"It's not like the market is crying for 100M bps," Sharma said.
Most LTE networks aren't even heavily loaded yet, because compatible devices haven't been on the market very long and are still relatively expensive, Marshall said. However, service providers and users may want some of the performance advantages of LTE-Advanced soon, just to preserve or extend the good experience subscribers enjoy now, he said.
"Service providers will rapidly use features of LTE-Advanced that don't dramatically impact their spectrum or network requirements," Marshall said. The result may be just the kind of invisible competence that carriers want.
"The speeds will hold better," Marshall said. "You won't see as much variation in performance as you move about the network."
Источник: Computerworld
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