認知無線網(wǎng)絡(luò)中合作頻譜技術(shù)研究.pdf

1、Wireless networks technologies are on a rapid increase in demand nowadays. Wireless networks are characterized by fixed spectrum assignment policy that is imposed by FCC allowing more and more number of unlicensed users

2、to transmit their signals in licensed bands so as to efficiently utilize the available spectrum due to the increasing demand for frequency spectrum and limited resource availability. Cognitive radios(CR) increase the eff

3、iciency of spectrum utilization(Quality of Service-QoS) through interference avoidance and local re-use of frequency bands originally designated for exclusive operation. Cognitive Radio can smartly senses and adapts with

4、 the changing environment by altering its transmitting parameters，such as modulation，frequency，frame format etc. The main challenges with cognitive radios are that it should not interfere with the licensed users and shou

5、ld vacate the band when required. These radios(CR) should be able to sense the signals at a very fast rate so as to make necessary decision whether to vacate or use the available spectrum. In this thesis，performance eval

6、uation is done between cooperative and non cooperative spectrum sensing schemes which uses Amplify-and-Forward algorithm，agility gain，energy detection，hard and Soft decision rules in CR in order to evaluate the performan

7、ce advantages of cooperation over non-cooperative Cognitive Radio networks .I tried to go a bit further to include another relay node at different relay time slot but the analysis of this scenario is not emphasized. Furt