Enhanced Double Threshold Spectrum Sensing Based Energy Detection

Radio Frequency(RF)spectrum is a restricted natural resource and needs to be utilized more efficiently in order to provide a diversity of services to a large number of users with higher data rates.The demand for this valuable radio resource is increasing due to a quickly expanding market of wireless broadband,multimedia users,and applications.It seems that it is more challenging to accommodate more wireless applications within this limited resource.However,the available spectrum bands resources are becoming lack due to given spectrum segmentation and the dedicated frequency allocation of the standardized wireless systems.Cognitive Radio(CR)technology attempts to deal with the conflicts between spectrum congestion and spectrum under-utilization by using the principle of dynamic spectrum management as a new strategy for spectrum access,which allows a CR user to use the licenced spectrum of a Primary User(PU)opportunistically.A crucial necessity for the CR technology is that it require in short time fill in spectrum unoccupancy while avoiding interference with PUs.This ability depends directly on spectrum sensing,which is the most important step on the determination of the reliability in a CR system.A difficult challenge of spectrum sensing for the CR is the ability to detect the state of the primary transmitter within a short time with a precise accuracy.Mainly all spectrum sensing techniques focus on primary transmitter detection,among this techniques we have the Matched Filter Detection(MFD),Cyclostationary Feature Detection,Energy Detection(ED),etc.Energy Detection(ED)has gained popularity as a spectrum sensing technique for CR because of its wide-ranging applicability and simplicity as well as its low computational and implementation costs.However,the conventional ED scheme is sensitive to the noise uncertainty effect,small fluctuations in noise power may cause a considerable decline in energy detection performance due to signal noise ratio(SNR)wall which prohibits the PU detection from being robust.In order to deal with ED weakness against the noise uncertainty several algorithm has been proposed such as double threshold,Dynamic-Double-Threshold,etc.This dissertation is extensively based on the study of Energy Detection technique for spectrum sensing.New-Double-Threshold algorithm on the framework of Energy Detection technique has been proposed and analysed through simulation studies using MATLAB2012 a which performs re-sensing with incrementation of number of samples under cooperative sensing.Pro-posed algorithm successfully raised the probability of detection.Here,‘OR' rule has been used to take decision about the presence/absence of the primary user.The performance of the proposed technique has been compared with the existing double threshold technique,and it showed significant performance improvement in terms of detection probability with nonconsideration of noise uncertainty.