Preserving unlicensed spectrum access for Wi-Fi® in 5 GHz

May 30th, 2017 by Alex Roytblat

In 2003, the World Radio Conference (WRC) allocated 5250-5350 MHz and 5470-5725 MHz frequency bands for use by Radio Local Area Networks (RLANs), which include Wi-Fi^®. WRC mandated that RLANs must protect a specified set of military-radar systems and adopted regulatory constraints on RLANs including Dynamic Frequency Selection (DFS) based on these radars’ characteristics and interference criteria.

Since 2003, Wi-Fi has become an essential component of the global telecom infrastructure. According to Cisco VNI, by the year 2020, the Wi-Fi industry will ship 3 billion Wi-Fi devices per year, with almost all devices supporting 802.11ac which operates in the 5 GHz band. Military radar systems have also evolved over the years with new fast-frequency-hopping and bi-static radars being introduced in the U.S. and some countries in Europe.

Various organizations have carried out a significant amount of work to study coexistence between RLANs and newly introduced radar systems which operate in the 5250-5850 MHz range.¹ In general, the studies conclude that RLANs implementing DFS cannot protect the new radars. As noted in one study, “currently, the only realistic mitigation technique identified to protect radars from RLAN interference is the DFS. However, the existing DFS techniques at 5 GHz have not been designed to protect radars that employ advanced and fast frequency hopping techniques as well as bi-static radars.” 

Military radar proponents in France, Germany, the U.S. and other countries continue to insist that existing international regulation must be modified at the next World Radio Conference in 2019 (WRC-19) to require RLANs to protect all radar systems in the band, including those that use bi-static and advanced fast frequency hopping techniques. Under the radar proponents’ logic, RLANs must protect the new radars. However, studies have clearly shown that RLANs cannot protect the new radars. Imposing this contradictory regulatory requirement would effectively preclude RLAN operations in the 5250-5350 MHz and 5470-5725 MHz bands – meaning that Wi-Fi would be unable to use these channels in the 5 GHz band if the requirement is imposed. With 95% of Wi-Fi devices shipped in 2021 expected to support 5 GHz, this is unacceptable.

Wi-Fi Alliance^® is working to inform regulators in the U.S. and Europe about the importance of preserving unlicensed frequency access for RLANs in 5 GHz to enable Wi-Fi innovation to continue. For more information or to get involved, please contact me directly at aroytblat@wi-fi.org.