Worldwide Interoperability for Microwave Access (WiMAX)
How WiMAX Works
(courtesy Intel Corp. & Marshall Brain, Ed Grabianowski, Sam Churchill)
In practical terms, WiMAX would operate similar to WiFi but at higher speeds, over greater distances and for a greater number of users. WiMAX could potentially erase the suburban and rural blackout areas that currently have no broadband Internet access because phone and cable companies have not yet run the necessary wires to those remote locations.
A WiMAX system consists of two parts:
- A WiMAX tower, similar in concept to a cell-phone tower - can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and 3 - 10 miles (5 - 15 km) for mobile stations.
- A WiMAX receiver - The receiver and antenna could be a small box or PCMCIA card, or they could be built into a laptop the way WiFi access is today.
A WiMAX tower station can connect directly to the Internet using a high-bandwidth, wired connection (for example, a T3 line). It can also connect to another WiMAX tower using a line-of-sight, microwave link(often referred to as a backhaul) is what allows WiMAX to provide coverage to remote rural areas.
What this points out is that WiMAX actually can provide two forms of wireless service:
There is the non-line-of-sight, WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range -- 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions -- they are better able to diffract, or bend, around obstacles.
There is line-of-sight service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it's able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth. Example video found here Towerstream located in NYC.
WiMAX IEEE 802.16
There has been little word of any upgrade from the current 802.16e standard to "Rev2". The focus is the move to 802.16m standard or true "4G", which would be a substantial upgrade. Other WiMAX network hardware upgrades occur as technology evolves. Example 1Example 2
802.16m = 4x faster than 802.16e
802.16m or "WiMAX 2.0" is currently under testing as we speak. Samsung said it plans to trial Release 2 via Clearwire in the United States and UQ Communications in Japan by late 2010. Yota also plans to put the first WiMax 2.0 units into service by the end of this year(2010), although The WiMAX Forum expects to see WiMAX Release 2 available commercially in the 2011-2012 timeframe.
Samsung and Yota are now testing Mobile WiMAX 2.0 (IEEE 802.16m). Its data transfer speed is four times faster than current Mobile WiMAX (802.16e) networks, thanks to MIMO antenna technology, which also improves spectral efficiency, and other enhancements.
By using 4X2 MIMO in an urban microcell, and 20 MHz TDD channel (double the usual 10 MHz), the 802.16m system can support both a 120 Mbit/s downlink and 60 Mbit/s uplink per site simultaneously, says the WiMAX Forum.
Mobile WiMAX Release 2 provides strong backward compatibility with Release 1 solutions. It allows current Mobile WiMAX operators to migrate their Release 1 solutions to Release 2 by upgrading channel cards or software on their systems. Also, the subscribers who use currently available Mobile WiMAX devices can communicate with new Mobile WiMAX Release 2 systems without difficulty.
4G systems, like Mobile WiMAX and LTE, will require 100-180 Mbps per sector, or close to 500 Mbps per tower. Clearwire CTO John Saw says microwave is critical. He estimates that 90 percent of the firm’s network uses the radio backhaul systems. DragonWave is the dominant supplier for Clearwire’s microwave backhaul network. AT&T and Verizon, which often monopolize fiber access in smaller communities, charge Sprint and Clearwire high rates to lease their fiber. But even with alot of "backhaul" a provider must have spectrum to deliver it or quality and performance suffers greatly. Spectrum is something Sprint and Clear have an abundance of in the U.S.
Top executives from Sprint, Cisco, Google, Comcast, Intel, Time Warner Cable and Bright House Networks sound off about Clearwire, WiMAX, and the future of the mobile internet.
Here at Sidecut Reports we always thought the woe-is-Clearwire views were short-sighted, and thought such opinions ignored the company’s biggest asset, its huge chunk of wireless spectrum in the 2.5 GHz range. This spectrum has an interesting history — some was initially owned by Worldcom, which was then obtained by Nextel and then by Sprint through various mergers and deals — but it is now all under Clearwire’s purview, with total DEPTH of anywhere between 100 MHz and 150 MHz in most major U.S. markets.
At the 700 MHz range, where AT&T and Verizon plan to deploy Long Term Evolution, the two big operators only have spectrum depth holdings of around 20 to 25 MHz each. As we’ve said before, this somewhat narrow depth of spectrum will initially mean LTE speeds far below the theoretical peak numbers that get tossed around in meaningless test situations.
Why is the depth important? When it comes to wireless services, the depth of spectrum that you have dictates how wide a pipe you can offer customers — with more spectrum DEPTH you can have faster speeds, more customers, etc. Right now your iPhone 3G experience in many U.S. markets stinks in part because AT&T doesn’t have a lot of spectrum depth at the frequencies it is using, so in a simple sense the channels and towers get clogged up. Even the company’s spectrum holdings at 850 MHz, which it is touting as a “high quality” savior for 3G chokepoints, only total between 25 MHz and 50 MHz of depth in major markets, according to AT&T senior vice president Kris Rinne, who confirmed those totals in an interview last week. While that might be enough to let a few more iPhone calls go through, compared to Clearwire’s holdings it’s pretty thin gruel.
Clearwire, on the other hand, has so much spectrum depth that it can deploy WiMAX today in big, thick channels while reserving enough spectrum depth to later deploy LTE if that makes sense, or perhaps now make some dough renting the spectrum to other players like T-Mobile. While spectrum alone won’t make WiMAX or Clearwire a successful business, we noted long ago that by itself the spectrum of the merged Clearwire-Sprint entity made the combination an even-money bet at worst. Now as other operators scramble to satisfy the growing need for mobile bandwidth, suddenly Craig McCaw’s latest spectrum play looks like a winning bet.
What is "Greenfield"?
From Wikipedia, the free encyclopedia:
In wireless engineering jargon, a greenfield is a project which lacks any constraints imposed by prior networks. The first cellular telephone networks were built primarily on tall existing tower structures or on high ground in an effort to cover as much territory as possible, quickly, and with a minimum number of base stations. They were developed with no regard for future capacity considerations or Frequency reuse.
Simply stated, many see “greenfield” as a bad thing.
As the demand for more and more wireless data at faster speeds skyrockets, sufficient spectrum becomes a challenge. Today much slower 3G networks can barely keep up with demand regulated by data caps and huge overage charges.
Simply stated Clearwire's all IP network be it WiMAX or LTE delivery, is built for one thing literately from the ground up; data and lots of it.
Ever wanted to know just exactly what was inside a Clearwire antenna tower cabinet?
Me too. That’s why we shot this video, at the launch of Clearwire’s Las Vegas network last summer. Now it is a nice video promotion for our latest report, Inside Clearwire: A Network Report, where we not-so-coincidentally talk about the network underpinnings of the company’s nascent national wireless broadband network.
Clearwire U.S. Spectrum Holdings as of 10/11
Clearwire U.S. Spectrum Holdings as of 2007 - pre Sprint merger
*Sprint 2.5Ghz Holdings are not reflected
Clearwire European Spectrum Holdings as of 2007
Clearwire Sells Majority Stake In Irish WiMax Network
Clearwire (NSDQ: CLWR) has sold off a majority of its assets in Ireland to Dublin-based Imagine Communications Group, freeing the company up to focus more on its rapid U.S. expansion. Financial terms of the deal were not disclosed, but Clearwire will become a minority shareholder.
Ireland was one of Clearwire’s early markets where it built out 4G-like services; however, it’s more of a distraction than anything these days as Clearwire rushes to blanket the U.S. with high-speed wireless services ahead of the competition.
Clearwire doesn’t break out specific numbers for its international markets, but it has the capacity to sign up about three million people in Belgium, Ireland and Spain, which is comparatively small to the 40-million plus it covers in the U.S. In those three countries, it has only 47,000 customers.
Imagine said its purchase of Clearwire, including its assets and technical team, is part of a EUR100 million investment to provide high-speed wireless. With Clearwire’s spectrum holdings there, it now has over 120mHz of spectrum in the 3.4 and 3.6mHz bands.
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