IEEE 802.11y-2008 is an amendment to the IEEE 802.11-2007 standard that enables data transfer equipment to operate using the 802.11a protocol on a co-primary basis in the 3650 to 3700 MHz band except when near a grandfathered satellite earth station. IEEE 802.11y is only being allowed as a licensed band. It was approved for publication by the IEEE on September 26, 2008. Background In June 2007 a "light licensing" scheme was introduced in 3650–3700 MHz band. Licensees pay a small fee for a nationwide, non-exclusive license. They then pay an additional nominal fee for each high powered base station that they deploy. Neither the client devices (which may be fixed or mobile), nor their operators require a license, but these devices must receive an enabling signal from a licensed base station before transmitting. All stations must be identifiable in the event they cause interference to incumbent operators in the band. Further, there is a requirement that multiple licensees' devices are given the opportunity to transmit in the same area using a "contention based protocol" when possible. If interference between licensees, or the devices that they have enabled, cannot be mediated by technical means, licensees are required to resolve the dispute between themselves. Features The 3650 MHz rules allow for registered stations to operate at much higher power than traditional Wi-Fi gear (Up to 20 watts equivalent isotropically radiated power). The combination of higher power limits and enhancements made to the MAC timing in 802.11-2007, will allow for the development of standards based 802.11 devices that could operate at distances of or more. IEEE 802.11y adds three new concepts to 802.11-2007 base Standard: Contention based protocol (CBP) Enhancements have been made to the carrier sensing and energy detection mechanisms of 802.11 in order to meet the FCC's requirements for a contention based protocol. Extended channel switch announcement (ECSA) provides a mechanism for an access point to notify the stations connected to it of its intention to change channels or to change channel bandwidth. This mechanism will allow for the WLAN to continuously choose the channel that is the least noisy and the least likely to cause interference. ECSA also provides for other functionalities besides dynamic channel selection based on quality & noise characteristics. For instance, in 802.11y Amendment, the licensed operator can send ECSA commands to any stations operating under their control, registered or unregistered. ECSA is also used in 802.11n.