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Cognitive Radio (CR) is an intelligent system for opportunistically accessing the idle resources and a solution for spectrum resources scarcity. The main purpose of this article is to analyze the performance of Energy Detection under Nakagami and Rayleigh fading channels and compare it with the case of when there is only AWGN. Probability of detection and probability of false alarm are used to characterize...
Fading is a significant part of any wireless communication system. Rayleigh, Rice and Nakagami-m are traditional fading channels but in some specific cases these fading distributions do not properly fit the experimental measured data, which demands the use of more general fading distributions. The Kappa-Mu distribution is general distribution that includes the Rice, the Nakagami-m, the Rayleigh, and...
In this paper an analytical approach is presented to determine the impact of frequency offset, timing jitter and additive white Gaussian noise (AWGN) on the bit error rate (BER) performance of a multi-carrier direct-sequence code division multiple access (MC-DS-CDMA) system over a Rayleigh Fading Channel. The analysis developed the pdf (probability density function) at the receiver considering combined...
In this paper, we consider a dual-hop decode-and-forward (DF) relaying system, in which the relay and destination nodes are subject to the arbitrary number of co-channel interferences (CCIs) as well as the additive white Gaussian noise (AWGN) on each node. Assuming that the interference channels are statistically independent and identically distributed (i.i.d) Weibull fading, we derive the outage...
This paper proposes the use of chirp-z transform (CZT) in spectrum sensing to achieve higher frequency resolution in spectrum monitoring. The CZT method can efficiently utilize the dispersed frequency spectrum of any desired band of interest. The performance of the proposed system over additive white Gaussian noise (AWGN) and Rayleigh channels is analyzed and presented through ROC curves. In order...
This paper addresses the performance degradation of near-capacity bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) when both demapping and decoding employ max-log-MAP algorithm. Two approaches are proposed to overcome the performance degradation: scaling of the transferred log-likelihood-ratios (LLRs) between demapping and decoding to mitigate the bias of LLRs values,...
This paper presents the simulation and performance analysis of WiMAX (Worldwide Interoperability for Microwave Access) system along with efficient wireless channels using real time image and speech transmission. WiMAX is the commercialization of the IEEE 802.16 standard, an evolving standard initiated at the National Institute of Standards and Technologies in 1998 before being transferred to the IEEE...
Cognitive radio network is defined as an intelligent wireless communication network that should be able to adaptively reconfigure its communication parameters to meet the demands of the transmission network or the user. In this context one possible way to utilize unused licensed spectrum without interfering with incumbent users is through spectrum sensing. Due to channel uncertainties, single cognitive...
The work is related to the use of Artificial Neural Network (ANN) assisted equalization as an aid to Maximal Ratio Combining (MRC) in order to improve bit error rate (BER) values of demodulated signals in wireless channels that have both Gaussian and multipath fading characteristics. Modulation technique used in this work is Bipolar Phase Shift Keying (BPSK) in Gaussian and multipath Rayleigh fading...
Multi-carrier code division multiple access (MCCDMA) systems receive a great deal of attention due to their great potential in achieving high data rates in wireless communication. This paper presents the simulation and analysis of MC-CDMA system performance when the data is sent and received over AWGN channel and Rayleigh channel. These two cases are simulated separately to show the performance of...
Cognitive Radio is a novel technology that has the potential to deal with the requirement and scarcity of the underutilized radio spectrum. A remedy to spectrum scarcity is to improve spectrum utilization by spectrum sensing where the secondary unlicensed users are allowed to access the underutilized licensed bands when the primary licensed users are inactive. Cooperative Spectrum Sensing (CSS) is...
This paper presents a joint timing and carrier frequency offset estimation scheme for Orthogonal Frequency Division Multiplexing (OFDM) over an Additive White Gaussian Noise (AWGN) channel, flat fading and frequency selective fading (Rayleigh channel). Estimating the correct Carrier frequency offset (CFO) minimizes the inter carrier interference (ICI). Orthogonality is maintained by using Maximum...
The work is related to the use of error correction coding and adaptive equalization as an aid to Maximal Ratio Combining (MRC) in order to improve bit error rate(BER)s of received signals in wireless channels with fading characteristics. Several modulation schemes are used in the transmission in Gaussian, multipath Rayleigh and Rician fading channels. The work adopts a few error correction codes and...
In this paper, the exact symbol error probability expression for a decode-and-forward cooperative relaying scheme using quadrature amplitude modulation (QAM) in the presence of Rayleigh fading and Bernoulli-Gaussian impulsive noise is derived. Different from, we only consider the practical receiver structure at the destination without requiring any knowledge of impulsive noise. Also, the source retransmission...
Adaptive relaying schemes significantly improve the performance of relay networks by switching the forwarding technique according to the reliability of the received signal. In this paper, semi-analytical solution for the power optimization in adaptive relay network is derived. Furthermore, the accuracy of the solution is confirmed by using the polyblock algorithm, which is an optimization tool for...
The focus of this paper is on the performance of an orthogonal frequency division multiplexing (OFDM) transmission system considering the combined influence of receiver noise, Rayleigh fading and the timing error due to imperfect slot synchronization at the receiver. Performance results are presented in terms of BER, BER improvement and BER-floor in presence of inter-channel interference (ICI) and...
Relay networks achieve high performance by utilizing cooperation between nodes that can be classified as multi-hop networks and cooperative MIMO relaying networks. Cooperative diversity is a transmission technique to overcome fading, multipath and inter-channel interference. As an important part of “spatial diversity” systems, cooperative diversity involving multi hop data relays is a solution to...
Spectrum sensing is a critical component of the Cognitive Radio that detects the presence of primary user signal in a channel. In this paper energy detection technique based on Neyman-pearson criterion is used to detect the presence of deterministic primary user (PU) signals in the channel. We have considered three different kinds of modulated signal such as BPSK, QPSK , DVB-T (2K mode) under additive...
Knowledge of the level crossing rates (LCR) and average outage durations (AOD) of the received signal-to-interference-plus-noise ratio (SINR) is very useful in designing and analyzing the communication system performance in a cellular environment with co-channel interference (CCI). In this paper, we study the analytical LCR and the AOD of the received SINR on Rayleigh fading channels with CCI. A closed-form...
In this paper, we propose a technique to improve the performance of Joint Channel and Network Coding (JCNC) scheme in Multiple Access Relay Channel (MARC). This technique is motivated by the observation that decoding quality is improved when channel output can be processed iteratively. Using different permutation patterns for different users, we enabled more scenarios that destination can apply iterative...
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