Hands off: 2 GHz is for WiFi traffic

September 19th, 2014, Published in Articles: EE Publishers, Articles: EngineerIT


Half of the traffic on the internet travels via WiFi in the licence-free spectrum of the 2 GHz band, however industry experts see potential problems ahead as mobile operators are eyeing the licence-free spectrum as useful spectrum for LTE back-hauling. The WiFi  spectrum must be protected, say industry leaders.

The Wireless Access Providers’ Association (WAPA) held its second “Future of Wireless Technologies” Forum in Gauteng on 17 September 2014. While the 17 and 24 GHz band were briefly discussed in two presentations by Regardt van de Vyver  of Multisource and Chris Sutherland of Miro respectively, the  main discussion focused on WiFi use in the 2 GHz (2400  to 2483,5  MH ) and 5 GHz (5,725 to 5,875 MHz) bands.

Jens Langenhorst, Spectrum Champion of the Wireless Access Providers Association chaired the second Future of Wireless Technology forum

Jens Langenhorst, spectrum champion of the Wireless Access Providers Association chaired the recent Future of Wireless Technology forum.

Several of the keynote speakers expressed their concerns about the future of WiFi. Nick Ehrke of Radwin said that overcrowding is becoming a problem as more and more companies are addressing the last mile by using unlicensed spectrum, particularly in the 5 GHz band.

He said it is a reality that competition is coming from the mobile network operators. “Vendors will bring more and more capacity to the market, using more channel bandwidth, causing more interference. Wirelessi nternet service providers’ (WISP) margins will be challenged as more competition comes to market. He made another valid point: “It doesn’t matter how much spectrum the regulator makes licence-exempt, the demand will outstrip supply and the solution to unlicensed spectrum  interference issues are not going to be fixed by the regulator or in better policing, but  by deploying interference mitigation technology.”

Johan Smit, executive, international and spectrum regulation at Telkom discussed the historical use of the 2,4 GHz band by Telkom and said that they are currently replacing obsolete legacy equipment with other systems, thereby moving them out of the WiFi  licence-exempt spectrum. He also said that the continued use of the band 2400 to 2483,5 MHz for WiFi must be ensured and protected and although licensed and coordinated use of the band is allowed according to ITU Article 5 and the South African table of frequency allocations, this use in future should be considered with care to ensure that licence-exempt WiFi use is protected.

There was also discussion about the requirement of sticking to the power limit specified in the regulations, which in the 2 GHz WiFi band is typically 100 mW EIRP.  In his presentation Smit  offered an explanation of what 100 mW EIRP means.  He quoted the ITU RR 1.161 which statesequivalent isotropically radiated power (e.i.r.p.) is the product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain).”  “Exceeding 100 mW EIRP means the system is no longer licence-exempt!”

Jens Langenhorst, spectrum champion of the Wireless Access Providers Association, raised the database issue. An up-to-date database would give WISP the opportunity to check what frequencies were already in use in an area in which they are planning to deploy and expand their footprint and thereby avoid causing interference to other WISPs and  their customers. All agreed that the question of who should be setting up and maintaining such a database remained unresolved.  If the regulator has to perform this, should it be construed that the licence-exempt spectrum is no longer licence-exempt?  Perhaps WAPA should take the lead in making this happen!

The Forum was well attended by industry and representatives from the International Communications Authority of South Africa (ICASA). During the panel discussion ICASA councillor William Stucke spoke about ICASA’s transparent processes. He said that the regulator uses a multiphase process which gives industry and the public several opportunities to make input as proposed regulations go through several steps from the first discussion paper to final regulations. He urged the industry to participate and make meaningful input with practical proposals. During each stage of the process written input is requested. He said that it is also possible after having submitted written input to request making an oral presentation. Industry has in the past not always made use of the opportunities to be part of shaping the regulations. He said that it was in everyone’s interest to do so!

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