While this technology works well for fixed access, it’s often been a real
challenge to use these frequencies for mobility due to its propagation
characteristics and to Doppler shifts (or more precisely the Doppler Effect),
which is more pronounced at higher frequencies above 3GHz.  From a
technology perspective, these shifts in frequency and wavelength result from a
source moving with respect to the medium, a receiver moving with respect to the
medium, or even a moving medium.  As modulated symbols are transmitted,
they interfere with one another, creating a phenomenon known as Inter Symbol
Interference (ISI).  ISI complicates symbol detection at the receiver,
often producing an unacceptably high bit error rate.

Consequently, there has been a perception that 3.5GHz spectrum should not be
used for mobility.  That thinking is now changing with the roll outs of
several 3.5GHz mobile WiMAX networks in Europe.  And if 3.5GHz can be
effectively used to deploy IEEE 802.16e mobile WiMAX networks, then operators
could provide both fixed/nomadic as well as mobile broadband access to
subscribers at a lower cost than at 2.5 GHz and lower frequencies. 

Indeed, there have been several deployments and recent announcements of
operators using 3.5GHz for IEEE 802.16e based WiMAX networks in Europe:

- Worldmax based in Amsterdam is using Beceem’s silicon and Motorola equipment
to deploy a nationwide mobile WiMAX network in the Netherlands at 3.5GHz . 
The operators’s service is currently deployed as a city-wide hot zone in
Amsterdam and early results have been quite encouraging. 

- Imagine Communication Group is deploying a nationwide mobile WiMAX network in
Ireland at 3.5GHz.  The network will use Motorola’s end-to-end WiMAX
solution to deliver voice and high speed data services to residential and small
to medium-sized enterprise customers as well as offering mobility in city
centers, using USB dongles.  More on Imagine’s WiMAX roll out later in this
article.

- Clearwire announced that it would deploy 3.5GHz mobile WiMAX in Malaga and
Seville, Spain next year, using RAN equipment from Alvarion and ZTE.  "We
intend to prove that WiMAX can work not only at 2.5GHz, but also at 3.5GHz,
which is the spectrum we have in Spain," Barry West, president of Clearwire
International, said during a press conference at the ITU Telecom World 2009 show
in Geneva.

- UK telecom regulator Ofcom has changed Freedom4′s spectrum license conditions,
allowing the operator to offer mobile WiMAX services across the U.K.  using
the spectrum it already owns.  (Note: Freedom4 is a joint venture between
Daisy Group and Intel Capital.) Freedom4 owns a broadband wireless spectrum
license consisting of two blocks of 84 MHz in the frequency band 3.6-4.2GHz. 
Ofcom’s move will enable Freedom4 to launch mobile WiMAX services, rather than
just fixed wireless access.  As a result, the company will be able to
directly compete with the UK’s five mobile network operators.  However,
Freedom4 has not disclosed any deployment time frames or other details of its
planned mobile WiMAX network. 

Imagine Communication’s WiMAX Network

According to a fact sheet provided by Imagine Communications Group, Ireland’s
broadband infrastructure is struggling to keep up with the demands of its modern
economy.  For broadband quality, Ireland ranks in 37th place out of 66
countries and behind countries such as Estonia, Greece, Poland, and Turkey. 
On the major cities ranking list, Dublin is ranked in 94rth place behind
locations such as Krakow, Ankara, Naples, Nanjing, and Istanbul.  One out
of three fixed lines in Ireland cannot get broadband and four out of 10 lines
can get a maximum of only 1Mbps.

In an attempt to greatly improve Ireland’s broadband infrastructure, Imagine
recently announced it will invest €100 million in upgrading to mobile WiMAX
technology, a move that could result in the creation of up to 200 new jobs. 
The Imagine WiMAX service is already in operation, with phase one of the rollout
covering 250,000 homes in Dublin, Wexford, Sligo, Tralee and Athlone to be
completed by mid-November 2009.  Imagine’s new network will not be
restricted to high-population areas, but will also be rolled out to smaller
towns and rural communities at a rate of 15 new WiMAX areas per month. 
Imagine’s CEO and founder Sean Bolger stated that Imagine plans to cover 90% of
the country by 2012 with WiMAX services. 

"Customers across Ireland will soon experience a leap forward in terms of
broadband access and speeds.  Motorola’s globally renowned WiMAX solutions
are quick to deploy, flexible and scalable and allow us to meet increasing
demand for next-generation voice and broadband data services at home, at work
and on the move," according to Bolger.

Sean Bolger, Imagine Communications

Bolger further stated that Imagine’s WiMAX service will debut at 8Mbps, but is
capable today of reaching 17Mbps and higher speeds.  According to
the companies website, the pricing for
consumers and businesses will be unveiled shortly, but Bolger promises it will
come at a lower price than current fixed line broadband services.  Bolger
told the

Irish Times it will be 50 percent cheaper than comparable Eircom products. 

He pointed out that Ireland has the highest fixed telephone costs in the world
and at €25.47 line rental is 70% higher in Ireland than the European average. 
Imagine also intends to allow other operators to wholesale its WiMAX service,
although he said it had not begun negotiations with anyone.

"4G broadband is not about speed but being more competitive." He went on to say
that Ireland has plenty of fiber, "now the problem is connecting to that fiber."
Bolger says WiMAX could solve that access problem. 

And Imagine owns lots of spectrum.  The company holds 88MHz of 3.5GHz
licensed spectrum in Dublin, Cork, and Waterford, 123MHz in Limerick and 60MHz
in the rest of the country.  In those cities, this is more than double the
35MHz held by each of the 3G mobile operators.

Motorola has agreed to provide a portion of the €100 million that Imagine needs
to replace its existing wireless nationwide infrastructure with WiMAX. 
Motorola will provide the RAN equipment as well as deployment, integration and
support services to Imagine.  Motorola’s Head of Sales commented, "Today’s
announcement is very significant for Motorola as we see Ireland as a key
strategic market for (mobile) WiMAX due to the digital divide and broadband
deficits which causes lower broadband speeds and higher prices than the rest of
Europe," he said. 

Intel is partnering with Imagine to supply technology for 3.5GHz mobile WiMAX
enabled notebook and netbook PCs.  Mr Jim O’Hara, General Manager of Intel
Ireland, said that WiMAX is a game-changing technology.  "Many people in
the country are operating on a 1Mbps speed at the moment, even if they think
they are paying for higher.  WiMAX is easily achieving 8Mbps, and this will
be increased.  Intel is going to provide WiMAX embedded laptops and PCs
from early 2010," Mr O’Hara concluded. 

These 3.5GHz mobile WiMAX deployments are great news for the WiMAX industry. 
As early indications suggest, these networks should be price competitive with 3G
networks while offering better performance and availability.  For true
mobility, the key question is when the mobile WiMAX embedded netbooks,
notebooks, and hand held devices are available that work at 3.5GHz.  We
hope it’s early next year.

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