认知无线网络的发展与以后研究方向.ppt

* * * * The reality of software radio and the support for moving a single radio through multiple standards has led the Institute of Electrical and Electronics Engineers (IEEE) to begin standardizing vertical handoffs between networks employing different standards (802.21 [802.21]). IEEE 802.22 ?s the first worldwide standard based on cognitive radio technology and is now in the process of standardization. Wireless Regional Area Networks (WRAN) focuses on constructiong fixed point-to-multipoint WRAN that will utilize UHT/VHF TV bands between 54 and 862 MHz. A distinctive feature of IEEE 802.22 WRAN as compared to the existing IEEE 802 standards is the base station coverage range, which can go up to 100 km if the Power is not an issue. The SDR Forum is an international, nonprofit organization dedicated to promoting the development, deployment, and use of SDR technologies for advanced wireless services and currently has over 100 member organizations. ---------------------------- An alternative but parallel effort is underway, sponsored by other groups who wish to develop SDRs with an open architecture approach to reconfigurable radio. These include the amateur radio community, kit manufacturers, and the GNU radio project.32 These groups do not use the SCA, but instead favor an architecture open to anyone who may wish to contribute to its evolution via common software development. For example, the GNU radio project is now providing a development circuit board that can be used with a number of openly available software download packages or users can design their own software implementations. --------------------- US Department of Defense Advanced Research Projects Agency (DARPA) Next Generation (XG) Radio Program. For example, Raytheon Corporation, among others, has developed and is testing a prototype XG radio system. --------------------------------------------- The Mobile and Portable Radio Research Group (MPRG) at Virginia Tech, developed the OSSIE (Open