scholarly journals Spectrum sensing in cognitive radio wireless networks for orthogonal freqnency division multiplexing in additive white Gaussian noise channel

2017 ◽  
Vol 1 (T4) ◽  
pp. 180-186
Author(s):  
Tri Minh Nguyen ◽  
Tu Thanh Nguyen ◽  
Phuong Huu Nguyen

Cognitive radio (CR) systems are one of the most interesting topics in recent years. They would enable more efficient use of the spectrum. The main problem of CR is how to dectect exactly the spectrum usage of primary users. There are many ways to do this, such as energy detector (ED), Axell’s detector, the sliding window detector, etc. Among them, cyclostationarity (CS) based dection methods attracted much attention because of their better results in low-SNR regimes. This paper will propose a method based on the autocorrelation property of orthogonal frequency division multiplexing (OFDM) signals in additive white Gaussian noise (AWGN).

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Saruti Gupta ◽  
Ashish Goel

Abstract The main drawback in the performance of the Orthogonal Frequency Division Multiplexing (OFDM) system is the higher Peak-to-Average Power Ratio (PAPR) of the OFDM signals at the transmitter side. Companding is a well-known technique useful for reducing PAPR in the OFDM signal. This paper proposes a new nonlinear companding scheme that transforms the magnitude of Rayleigh distributed OFDM signal of specific degree into trapezoidal distribution. Additional design parameter is used in the proposed companding scheme to make the companding function more flexible. In the designed OFDM system the companding function has more degree of freedom which improves the PAPR and bit error rate (BER) parameters of the designed system. It has been demonstrated that the designed companding scheme provides more flexibility to accomplish an optimum trade-off between the performance parameters PAPR and BER of the designed OFDM system.


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