期刊名称:International Journal of Information and Communication Technology Research
电子版ISSN:2223-4985
出版年度:2012
卷号:2
期号:7
出版社:IRPN Publishers
摘要:In this paper, an adaptive Orthogonal Frequency Division Multiplexing (OFDM) system, with a precoded cyclic prefix (PCP), will be proposed to address the recent need of robust and flexible transmission technique in Cognitive Radio (CR) communications which is not clarified until now. Identification of PCP-OFDM signals is therefore of great importance for the design of fair spectrum sharing mechanism, particularly at very low signal-to-noise ratio (SNR) when synchronization is not achievable. The precoded cyclic prefix, multiplexed with the data-carrying OFDM signals, provides one unique and recognizable feature of PCP-OFDM signals. In this paper, the network consists of sender, a destination and a third station, which is used as a relay is analyzed. The data that is sent to the sender is considered to be OFDM with PCP. The analysis of this system will be made which is not clarified until now. The channels are modeled containing noise, Rayleigh fading and path loss. Moreover, different combining methods and diversity protocols are compared. To combine the incoming signals the channel quality should be estimated as well as possible. Amplify and Forward (AAF) will be applied in this system. Also, the effect of the positions of the relay will be studied.