or Data Encryption Standard (DES) during data transfer. Further features of the MAC layer include power saving mechanisms (using sleep mode and idle mode) and handover mechanisms. A key feature of 802.16 is that it is a connection-oriented technology. The subscriber station (SS) cannot transmit data until it has been allocated a channel by the base station (BS). This allows 802.16e to provide strong support for quality of service (QoS). QoS Quality of service (QoS) in 802.16e is supported by allocating each connection between the SS and the BS (called a service flow in 802.16 terminology) to a specific QoS class. In 802.16e, there are 5 QoS classes: The BS and the SS use a service flow with an appropriate QoS class (plus other parameters, such as bandwidth and delay) to ensure that application data receives QoS treatment appropriate to the application. Certification Because the IEEE only sets specifications but does not test equipment for compliance with them, the WiMAX Forum runs a certification program wherein members pay for certification. WiMAX certification by this group is intended to guarantee compliance with the standard and interoperability with equipment from other manufacturers. The mission of the Forum is to promote and certify compatibility and interoperability of broadband wireless products. See also WiBro WiMAX WiBAS WiMAX MIMO Wireless mesh network 4G LTE References External links IEEE Std 802.16-2004 IEEE Std 802.16e-2005 IEEE Std 802.16-2009 IEEE Std 802.16-2012 IEEE Std 802.16.1-2012 IEEE Std 802.16.1-2017 The WiMAX Forum The implications of WiMAX for competition and regulation A paper of the OECD, Organisation for Economic Co-operation and Development IEEE 802.16m Technology Introduction IEEE 802 WiMAX Wireless networking standards