b. WiMAX standards
WiMAX technology is based on IEEE 802.16 . The IEEE standard serve as the basis for the WiMAX Forum's WiMAX air interface specifications at the PHY and MAC layers. Standards evolve through time to support new capabilities and to improve performance. There are three versions of the IEEE 802.16 standard that are key to the WiMAX Forum Certified program:
1. IEEE 802.16-2004 (or 802.16d): Based on Orthogonal Frequency Division Multiplexing (OFDM), it supports fixed and nomadic access. WiMAX Forum Certified equipment was certified for conformance only to this standard until mid-2008
2. IEEE 802.16e-2005 (or 802.16e). Based on Orthogonal Frequency Division Multiple Access (OFDMA), this standard version supports fixed and nomadic access, but it also includes additional capabilities to serve mobile access. The WiMAX Forum Certification program issued the first certifications for the 2.3GHz band in April 2008 and for the 2.5GHz band in June 2008
3. IEEE 802.16m: Currently under development, the new version of the standard will include improved mobile access and voice services and is a candidate for inclusion as one of the future ITU IMT-Advanced technologies. The WiMAX Forum is committed to preserving compatibility with the IEEE 802.16e-2005 standard, which will enable operators to roll out 802.16m-based equipment within their existing networks
On the basis of the IEEE 802.16 standard, the WiMAX Forum develops system profiles, which select a subset of capabilities included in the standard to define the capabilities that all WiMAX products are required to support. There are currently two system profiles: one for Fixed WiMAX (IEEE 802.16d) and one for Mobile WiMAX (IEEE 802.16e-2005). Additional capabilities may be added to the system profiles when a new version of the standard is approved.
WiMAX is a technology based on the IEEE 802.16 specifications to enable the delivery of last-mile wireless broadband access as an alternative to cable and DSL. The design of WiMAX network is based on the following major principles:
- Spectrum: able to be deployed in both licensed and unlicensed spectra.
- Topology: supports different Radio Access Network (RAN) topologies.
- Interworking: independent RAN architecture to enable seamless integration and interworking with Wi-Fi, 3GPP and 3GPP2 networks and existing IP operator core network.
- IP connectivity: supports a mix of Ipv4 and Ipv6 network interconnects in clients and application servers.
- Mobility management: possibility to extend the fixed access to mobility and broadband multimedia services delivery.
WiMAX has defined two MAC system profiles the basic ATM and the basic IP. They have also defined two primary PHY system profiles, the 25 MHz-wide channel for use in (US deployments) the 10.66 GHz range, and the 28 MHz wide channel for use in (European deployments) the 10.66 GHz range.
The WiMAX technical working group is defining MAC and PHY system profiles for IEEE 802.16a and HiperMan standards. The MAC profile includes an IP-based version for both wireless MAN (licensed) and wireless HUMAN (licence-exempt).
IEEE Standard 802.16 was designed to evolve as a set of air interfaces standards for WMAN based on a common MAC protocol but with physical layer specifications dependent on the spectrum of use and the associated regulations.