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In this paper, an optimized cooperative spectrum sensing (CSS) network, in which each cognitive radio (CR) uses multiple antennas and an improved energy detector is proposed. The performance is evaluated by optimizing the network parameters such as number of CR users and normalized detection threshold. We have derived the suitable expressions for optimum value of normalized threshold in Rayleigh fading...
Cognitive radio is an evolving technology which is able to solve the problem of spectrum inefficiency. Every wireless system occupies some bandwidth but there is limited spectrum which is allotted to the licensed user. This allotted spectrum is sometimes underutilized. Cognitive radio senses the spectrum, find the available space in the spectrum and allot it to the unlicensed secondary user without...
This paper presents the performance analysis of spectrum sensing systems based on double threshold energy detection in which noise uncertainty and κ-µ fading channels, which represents the small-scale variations of the fading signal under both line-of-sight and multipath scenarios, coexist. Receiver Operation Characteristics (ROC) are obtained regarding the double threshold scheme and comparisons...
Sparse code multiple access (SCMA), as a new non-orthogonal multiple-access technique, is capable to achieve massive connectivity and grant-free transmission in wireless radio access. In order to support decoding of signal from simultaneous accessing users, active users detection and channel estimation is needed, which requires significant pilot overhead, especially in channels with relative small...
This paper proposes a technique for intercepting the symmetric signals and uses the example of the widely used Triangular FM waveform as a case study, due to its importance. The interception process involves performing convolution of the received signal with itself. Due to the symmetric nature of the Triangular FM waveform, the output of this self-convolution procedure is the same as the autocorrelation...
In this article, we carryout performance analysis on energy detectors in myriads of generalized fading environments. We utilize a new “exponential-type” contour and finite-range integral representations for the generalized M-th order Marcum Q-function QM(α,β) when its real order M>0 is not necessarily an integer. The accuracy of the new alternative integral representation for Marcum Q-function...
In this paper, an adjustable multiple relay selection (MRS) scheme for cooperative communication with amplify-and-forward (AF) relay under frequency selective channels is proposed. In the proposed scheme, the relays are ordered firstly by the end-to-end SNR, then the relays are sequentially selected out from N relays and the number of cooperating relays is adjusted dynamically according to the current...
The current policies of spectrum allocation leads to inefficient use of spectrum, making it scarce but the truth is, spectrum is not scarce but is underutilized. In today's era dynamic spectrum access is the need of the hour and cognitive radio is a novel technology which improves spectrum utilization. In this paper overview of cognitive radio along with spectrum sensing techniques is taken into account...
This paper investigates the performance of an energy detector with single antenna reception operating over κ-μ shadowed fading. Novel accurate expressions for both the average detection probability and the average area under the receiver operating characteristic curve (average AUC) are derived using the well-known probability density function (PDF)-based method. The unified framework shows that the...
Recent advancement in vehicular wireless applications is also a major contributing factor in spectrum scarcity. Cognitive radio technique can be applied to vehicular networks to fully exploit the underutilized licensed spectrum. Fast and reliable detection of primary user is the key component of cognitive radio networks. Energy detection (ED) based spectrum sensing is a viable choice for vehicular...
Power line communication (PLC) utilizes power lines for the purpose of electronic data transmission. The performance of a PLC system is significantly affected by the additive and multiplicative power line noises; the additive noises are of two types, namely background noise and impulsive noise. Whereas, the multiplicative PLC noise leads to fading in the received signal strength. In this paper, we...
The development of next-generation networks has been driven by a number of use cases aimed at supporting innovative applications and services. Among these drivers the Internet of Things has gained momentum due to its potential to leverage Machine Type Communications (MTC), a term used to denote machine-centered communications among sporadic, bursty traffic generating devices. While scalability issues...
Carrier aggregation (CA) is a technique introduced in LTE-Advanced to achieve a higher throughput by increasing bandwidth. In this work, the spectrally efficient frequency division multiplexing (SEFDM) bandwidth compression technique is utilized to enhance CA performance. This work reports experimental demonstration of SEFDM and shows that up to 7 component carriers (CCs) can be aggregated in a given...
A robust digital modulation scheme, called differential on-on keying (DOOK), is presented in this paper which outperforms the conventional on-off keying (OOK). In this scheme, a sinusoidal signal is transmitted during the first half of the bit duration while a replica or an inverted version of the sinusoidal signal is transmitted during the second half for logic one or logic zero, respectively. Non-coherent...
The extrinsic information transfer function of multi-user detection for synchronous CDMA is evaluated depending on the load of the system and the signal to noise ratio. This transfer function is used to discuss the benefits of putting redundancy into spreading or coding. Finally, it is shown how low-density parity-check codes can be designed for a specific system.
Maximum a posteriori (MAP) sequence detection for channels with intersymbol interference (ISI) has previously required knowledge of the channel sampled impulse response (SIR). Generally the SIR coefficients are determined via least mean square (LMS) or recursive least squares (RLS) estimation algorithms. For many unguided media channels such as mobile radio and high frequency radio which exhibit a...
This paper presents double stage energy detectors for spectrum sensing (SS). The first stage carries fixed threshold (FT) based energy detector (ED), and the second stage carries adaptive double threshold (ADT) based ED. Numerical analysis has been carried out on the basis of results obtained and shows that proposed scheme outperforms the cyclostationary based sensing method and adaptive SS by 12...
The performance of spectrum-sensing based energy-detection (ED) in cognitive radio networks (CRNs) over the extended generalized-K (EGK) fading channels is analyzed. More specifically, exact and accurate analytical expressions for the average detection probability under different detection scenarios, such as, single channel (no diversity), diversity reception, and cooperative spectrum sensing, are...
This paper deals with a cancellation multiuser detector for CDMA communication systems. Proposed receiver is supposed to be used at the end of up-link channel, leading to consider multipath fading phenomena. Proposed receiver approach consists in performing a weighted selective cancellation of the co-channel interfering signals, divided in two different groups according to the received power level:...
This paper addresses the problem of multiuser detection in multipath fading code-division multiple-access (CDMA) channels with non-Gaussian noise. A robust multipath decorrelator is proposed to mitigate the multiple-access interference and the multipath interference, and to ameliorate non-Gaussian ambient noise. The performance of the proposed multiuser detector is assessed via computer simulations...
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