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Rural broadband wireless

Prof Reg Coutts, Information Age

23/10/2007 00:37:41

Wireless broadband technologies have evolved as part of the deployment of broadband infrastructure albeit for different contexts in both developed and developing countries. Wireless technologies have a particular niche in the different ways of developing countries that do not have a mature copper network for DSL and in developed countries for application in rural environments and difficult locations.

WiMAX has arisen very rapidly in parallel with mobile technologies such as 3G as a serious alternative in many applications. The purpose of this article is to help separate fact from hyperbole that inherently pervades the technology space.

Radio spectrum and standards, together, produce the necessary oxygen to enable wireless and mobile systems and breathe their magic. However, unlike the evolution of mobile technologies that have forged and secured international agreement on spectrum over 20 years, WiMAX, the new boy on the block, faces the challenge of finding suitable unoccupied radio spectrum.

While making significant headway in just a few years, the spectrum bands for WiMAX are still fragmented within the major regions of the world and this is an obstacle to the development of low-cost globally compatible equipment. The WiMAX community of equipment vendors and operators have focused on the 2.5GHz and the 3.5GHz bands for initial mobile WiMAX equipment availability.

WiMAX conforms to two broad standards, the IEEE802.16d standard decided in 2004 for which certified equipment is available and the other mobile WiMAX IEEE802.16e standard decided in 2005 for which certified equipment has yet to appear.

In Australia Telstra has rolled out its 3G network Next G at 850MHz to encompass the earlier rural CDMA network which in addition to providing 3G mobile services can with the upgrade to HSPA offer wireless broadband service to rural users.

A new player OPEL, jointly owned by Optus and Elders, now has won the Government contract to roll out a wireless broadband service by June 2009 in competition with Telstra based on WiMAX.

The class licensed 5.8GHz band in my view is not suitable for broad WiMAX deployment.

The 2.3GHz band suitable for WiMAX is available to be used in rural Australia except for the Northern Territory.

Currently the majority of this band is held by Austar which is still considering plans to roll out a rural broadband service based on WiMAX in competition with OPEL and Telstra.

Unwired which is in an alliance with Austar with respect to the 2.3GHz band, offers a "pre-WiMAX" nomadic broadband service in Sydney and Melbourne.

Unfortunately spectrum below 1GHz such as 700MHz, next in priority for global equipment development and more suitable for mobile WiMAX, won't be available until post 2012 with the transition to Digital TV. However, for fixed rural broadband WiMAX at 2.3GHz with a rooftop antenna is comparable in technical performance to HSPA at 850MHz.

As well as doing a broad comparative assessment of WiMAX and HSPA for their claimed benefits, my analysis has considered a "hypothetical rural town" where DSL is range limited to 4km from a central exchange. From our modelling and canvassing of industry-wide perspectives, it is my opinion that both WiMAX at 2.3GHz and HSPA at 850MHz for rural application can provide similar user data rates of 8-12 Mbit/s expected of ADSL1 and ADSL2+ within what is termed the dominance zone of a single base station site.

While the dominance zone would be about 8km out from the base station, the service area for acceptable service would extend beyond this out to nearly 20km for WiMAX and 35km for HSPA, but where the user data rate would drop to about 2Mbit/s.

In practice, further base stations would be established to extend a network of cells to meet demand and assure acceptable service levels.

The report discusses the broad issues of radio network planning which have various differences of approach between WiMAX and HSPA. The report also discusses why peak bit rates can for light loading be expected to obtained by a great majority of users within the dominance zone.

The main thrust of my analysis has been on the technical capability comparison between of 3G/HSPA and WiMAX for fixed rural application including the likely timing of the availability of equipment and new features such as MIMO.

It is my opinion from years of experience that many supposedly "fabulous" technologies take forever to reach the market and only occasionally deliver the projected commercial gains espoused at the outset.

The report discusses the task of choosing between the two WiMAX standards given a time to market requirement of only two years. In the case of WiMAX, the choice is between available industry certified IEEE802.16d equipment supplied by multiple vendors or pre IEEE802.16e equipment from a single vendor.

Either way a transition at a later date to the certified IEEE802.16e equipment will be required which will potentially include changing customer equipment.

In the case of 3G and HSPA, certified equipment from multiple vendors is available and the medium-term evolution is very credible. The longer-term view is more contentious and abounds in hyperbole: one well known Australian industry commentator claims 3G is obsolete!

The global rivalry between what is seen as the old "telco model" and the new "consumer content and devices" model is increasing in intensity and fuels the claims of the two "camps" as I choose to describe them.

The availability of sufficient backhaul capacity to interconnect the rural broadband with the core network is an important issue. While users are potentially able to access much higher data speeds with broadband wireless, their user experienced data rate could in practice be constrained by a backhaul bottleneck unless adequate capacity is provided.

My analysis has very broadly viewed the problem from the perspective of both the incumbent HSPA provider and that of the new WiMAX provider, and how current WiMAX IEEE802.16d technology is used effectively as a backhaul alternative to microwave and leased lines for both parties.

Technology and equipment choice of course are only part of the commercial context for the industry and a brief discussion is provided.

A suggested framework for considering, and indeed better understanding such comparisons of, alternative technology is to construct a scenario framework in the particular application context, identifying the key stakeholders and their critical timing for decisions.

The alternatives can be then played out so to speak to allow focus on the key risks and opportunities for the stakeholders.

In summary, I believe that the WiMAX technology developments will divert the longer term technology evolution towards 4G which will exploit the flexibility strengths of WiMAX.

However, in my opinion it is critical that Australia maintain its credibility as a sophisticated, timely adopter of the best of global technology and should resist being used as a test market to reduce technology risk for global suppliers rather than supporting sustainable rural infrastructure investment.

i>Prof Reg Coutts is Director, ACS Telecommunications Board