Donut Shaped Ultra wideband Antenna for Cognitive Radio Application

In the last few decades there have been significant use of Cognitive radio and UWB technologies. These technologies are used for efficient use of Spectrum for short range wireless communications. In 2002, FCC has released a wideband of 7.5 GHz (From 3.1GHz to 10.6GHz) as unlicensed to use it . UWB antennas proves to be a suitable candidate for spectrum sensing in cognitive radio and in UWB transceiver. Since antenna dimensions are frequency dependent, designing an antenna for wideband is a tough job. This paper discusses the gradual techniques to obtain ultra wide bandwidth (2.23GHz-11.4GHz) from narrowband patch antenna. Also the various antenna parameters of proposed antenna design and its simulated results are analysed

EOAODV: Routing Protocol for Cognitive Radio Network

Cognitive Radio (CR) technology provides promising and a new solution to improve the spectrum utilization. In recent years, cognitive radio technology (CR) has been proposed to allow unlicensed secondary users (SUs) to opportunistically access the channels unused by primary users (PU). This paper focuses on designing Enhancement of Opportunistic Ad-hoc On Demand Distance Vector (EOAODV) routing protocol that uses shortest distance, Expected Transmissions Count (ETC) and residual energy as a parameter to select the most reliable link and the next forwarding node. The selection of route in the network by the traditional AODV is based on hop count. It is proposed to achieve a gain of Opportunistic Routing (OR) with AODV for cognitive radio wireless sensor networks (CRWSN) to improve its efficiency. In the OR work the nexthop node selection was based on only Expected Transmission Count (ETC). In this case if the same node is selected as nexthop for many times, energy of that node is drained and node may be dead. To overcome this problem, a technique is contributed that is energy based nexthop selection ie. EOAODV. The ETC is computed based on the quantized value of RSSI of the links with residue energy in the forwarding node. Using ETC the reliable link is computed and stored in routing table. The packets are tranmitted to the destination using channel details and the next hop, available in the routing table. The next hop selection is based on high energy in the nodes, shortest distance and least ETC