Wi-Fi, which refers to certified products based on the IEEE 802.11 standards, is widely used to build wireless local area networks (LAN) in both business and residential environments. These LANs typically use unlicensed 2.4 GHz spectrum, removing the need to apply for spectrum from ICASA for your wireless network.
Wi-Fi is however not only used for wireless LANs and hotspots. The affordability of Wi-Fi equipment, coupled with the fact that it generally utilizes unlicensed spectrum, makes it an attractive technology to cheaply build large wireless networks often spanning tens of kilometers.
In South Africa there are numerous commercial Wi-Fi Internet providers like Uninet and Aerosat, many of which are represented by the Wireless Access Providers’ Association of South Africa (WAPA). There are also many non-commercial community networks like JAWUG (Johannesburg Wireless User Group), PTAWUG (Pretoria Wireless User Group) and CTWUG (Cape Town Wireless User Group) which use Wi-Fi to connect members to each other. Wi-Fi is even used by larger telecoms providers to serve their clients’ needs, both as a wireless LAN technology and for providing backhaul connectivity.
One of the problems with a Wi-Fi device which is bought off the shelf is its limited range. Most 2.4 GHz Wi-Fi routers with a standard antenna have a range of around 30 meters indoors and approximately 100 m outdoors. This range is not adequate for wide area networks (WAN), and the legal power output limitation of 100 mW in the 2.4 GHz frequency range means that users are not permitted to increase power to increase the range.
Another unlicensed frequency band, the 5.4 GHz to 5.8 GHz range, allows for higher power output. The 1 Watt legal limit of the 5 GHz frequency power output is ten times higher than the 2.4 GHz band, making longer range connections possible. There is also less noise in this frequency band. The higher power output coupled with less interference means that most serious Wi-Fi network operators use the higher frequency spectrum for their services.
Many smaller players however still opt for a directional antenna on their 2.4 GHz router which can improve the range to many kilometers with line-of-sight. These antennas may however result in an illegal effective power output which is transmitted.
The effective power output (Effective Isotropic Radiated Power – EIRP) is calculated using the transmitter-amp power, the antenna gain in decibels (dBi) and the cable loss, also in decibels (dB). The use of a 20 dBi gain antenna on a standard Wi-Fi router with a 100 mW power output will result in an effective power output of 10 Watts – a hundred times higher than the legal limit of 100 mW. This output may be illegal and could cause problems with ICASA who polices the airwaves.
According to JAWUG user Xarion not many Wi-Fi players adhere to the 100 mW rule. “I can put my money on it, no WISP or ‘legal’ [Wi-Fi] provider adheres to this rule,” he said. “Personally I think the law is completely useless because there is no way anyone can have a decent link with 100mW EIRP, with all the noise in the ether these days.”
A Pretoria Wireless User Group (PWP) member, who asked to remain anonymous, said that it may be technically illegal, but that it has become common practice to use high gain antennas. “You can walk into various PC and Wi-Fi shops and buy the equipment without any questions,” he said.
WAPA Chairman Joe Botha says that their association’s code of conduct does not specifically deal with issues of EIRP, and that there is a fair amount of confusion on EIRP issues. “The definitions of EIRP and the locations of measurement of this EIRP value are debatable, and hence unclear in the South African Context at this stage,” says Botha.
“There is significant confusion in the marketplace and within ICASA on these issues, as is evidenced by the lack of any enforcement activity on EIRP issues. ICASA to date has chosen to focus its enforcement activity in this area on Type approval compliance as well as interference complaints from other licenced users of these spectrum ranges,” Botha said.
Botha points out that WAPA has set agreed limits for antenna gain on 2.4GHz and different limits for 5.4GHz. “In the 5.4GHz band where the majority of WAPA members are operating fixed wireless (long range) services, the EIRP limitation set in the South African Table of Frequencies is 1000mW or 30dBm. This broadly means that you can take a 100mW radio and add a 20dBi Antenna (with some other variables in between), and still be within the 1000mW EIRP range,” said Botha.
Xarion added that the only way to ‘control and make the airwaves and the law more usable is to put a limit to the power going into the antenna, not limit power coming out of it.’ He added that it will be “great to have a discussion with ICASA regarding this massive grey area that everyone basically ignores because it is impossible to implement.”
ICASA was contacted for comment, but was not available to provide insight about the Regulator’s position on this issue.