WiMAX in the balance

On the one hand, the Independent Communications Authority of South Africa (ICASA) has been doing its utmost to hurry the process whereby it will define its procedures and criteria for the allocation of WiMAX spectrum in the 2.6 GHz and 3.5 GHz band.

On the other hand, experts at the recent SatCom conference shocked delegates when they pointed out, with supporting information, that WiMAX deployments on 2.6 GHz and 3.5 GHz ranges "wipe out" satellite services on the C-band and extended C-band range.

This, they said, could have a crucial impact on the television transmissions and even pose a potential threat to the 2010 Soccer World Cup broadcast. Now it is up to ICASA to play Solomon in this matter and discern what spectrum will be allocated to which service provider, and at what frequency, so as to avoid massive interferences between the two services.

A CLOSER LOOK AT WIMAX

Short for Worldwide Interoperability for Microwave Access, WiMAX is a standard for the wireless delivery of high-speed broadband to laptops and desktops while eradicating the local loop of copper wires or fibre-optic cabling for last-mile access.

The WiMAX Forum, the industry-led, non-profit organisation formed to certify and promote the compatibility and interoperability of broadband wireless products, has endorsed the initial profiles for 2.3 GHz, 2.5 GHz, and 3.5 GHz band ranges for mobile applications.

Frost & Sullivan research analyst Saverio Romeo makes a distinction between unlicensed and licensed WiMAX. He says licensed WiMAX is always allocated the 2.5 GHz and the 3.5 GHz band ranges, which guarantee better quality of service. Unlicensed WiMAX, he says, works on the 5.8 GHz band. Richard Hurst, analyst at research firm BMI-TechKnowledge, says WiMAX on the 2.6 GHz and the 3.5 GHz spectrum is coveted by WiMAX proponents because it enables them to deliver voice and broadband Internet access with wide area coverage, while offering higher data rates.

Industry players and consumers alike have been pleading with the government to unleash WiMAX because of its relatively low costs, rapid deployment capability, extensive scalability, and capacity to deliver voice, data and video, particularly in comparison to ADSL.

WHAT`S THERE TO CONSIDER?

There have been reports that satellite systems operating in the 3.4 GHz to 4.2 GHz band (C-band) are being crippled by broadband wireless access systems like WiFi and WiMAX.

Satellite communications technology in the C-band is used for broadcasting television signals, Internet delivery, data communication, voice telephony and aviation systems. Government needs to recognise the potential for massive disruptions to C-band satellite communications, radar systems and domestic microwave links, if spectrum is inappropriately allocated to, and frequencies inappropriately assigned for, terrestrial wireless applications in the C-band.

This is according to the Position Paper on Interference in C-band by Terrestrial Wireless Applications to Satellite Applications, which has now been adopted by International Associations of the Satellite Communications Industry.

The paper states that C-band for satellite communications is vital for many developing countries because it facilitates intercontinental and global communications, as well as providing a wide range of services. These include distance learning, telemedicine, universal access, disaster recovery and television transmission. Not only that, but the C-band frequencies were assigned for satellite downlinks more than 40 years ago.

LORD OF THE BANDS

The position paper elaborates on the conflict between satellite services and WiMAX networks. Terrestrial wireless applications emit signals from many locations, in all directions, simultaneously. These signals are powerful enough to saturate the sensitive C-band satellite receiving systems, causing a potential for total loss of service in the C band.

Reports on this conflict were recently confirmed when WiMAX field trials in Hong Kong knocked off television feed for 300 million households throughout Asia. The position paper also says that the sensitivity of C-band satellite-receiving systems means that they may be disrupted by mobile terrestrial use of frequencies in immediately adjacent bands.

Telemedia`s MD Peter Bretherick comments: "From what we have seen, where you have satellite dishes receiving signal on the C-band range, WiMAX causes such interference that it makes it near impossible to receive signal. On the extended C-band range, our satellite service was completely obliterated by WiMAX networks operating on the extended C-band range."

Telemedia is involved in the supply, installation and service of professional radio and television broadcasting equipment, and satellite distribution.

For the two technologies to coexist, VSAT Forum general-secretary David Hartshorn advocates that an exclusion zone of between 50km to 60km around a WiMAX base station be required to ensure it does not create an interference risk to satellite services on C-band and extended C-band.

Bretherick suggests that WiMAX be allocated spectrum anywhere but on the C-band and extended C-band range.

DIGITAL DIVIDER?

Frost & Sullivan`s Romeo acknowledges that WiMAX technologies have a clear social aim, which is building digital communities: "WiMAX seems to be a good candidate to develop networked communities in rural and peripheral areas." However, he questions the claims around WiMAX being the technology to bridge the digital divide and calls for a careful study on the issue.

Romeo argues WiMAX on licence bands 2.5GHz and 3.5GHz requires huge cash flow for national coverage and high costs for metropolitan areas, whereas unlicensed WiMAX on the 5.8 GHz band has the advantage of no licence fees, which drops the deployment costs but requires a greater number of base stations to reduce interference.

"Licensed and unlicensed WiMAX is both problematic in a rural and peripheral context because of technological and costs constraints," he adds.

Romeo points out a WiMAX solution cannot guarantee the efficiency of digital communities. "In fact, digital communities already deployed in Western countries use a combination of fixed-line networks, WiFi, and WiMAX solutions.

"These integrated networks are difficult to build in rural environments because of a lack of basic telecommunications infrastructures. The costs associated with licensing and deployment of the technology is a barrier that requires a huge commitment from the government."

He concludes that, unless there is involvement by governments at regulatory and investment levels, WiMAX as an access technology will, in itself, not be able to bridge the divide, particularly in areas where telecommunications infrastructure is poor and obsolete.

GOVERNMENT`S CHOICE

Arthur Goldstuck, MD of ICT research company World Wide Worx, notes: "Technology aside, whether WiMAX broadens or narrows the digital divide depends entirely on whether government allows it to do so."

He maintains: "Government, through the regulator, has the ability to enable a competitive environment for WiMAX, one in which any provider is allowed to establish infrastructure and roll out networks. It further has the ability to make this roll-out contingent on providing low-cost access to disadvantaged communities.

"If it does this, the platform exists to narrow the digital divide, but then a range of further resources would still be required, from computers and computer literacy programmes to more fundamental infrastructure programmes. But at least the potential will exist."

He adds that if government chooses to allow WiMAX provision only from the incumbent providers of such services, then WiMAX will be irrelevant to the disadvantaged, and, indeed, it will widen the digital divide.