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We propose an Iterative Detection and Decoding (IDD) scheme with Low Density Parity Check (LDPC) codes for Multiple Input Multiple Output (MIMO) systems in block-fading receivers and fast fading Rayleigh channels. An IDD receiver with soft information processing that exploits the code structure and the behaviour of the log likelihood ratios (LLR)'s is developed. Minimum Mean Square Error (MMSE) receivers...
The Automatic Identification System (AIS) is used worldwide as a maritime system for identifying and locating vessels by exchanging data in Very High Frequency (VHF) band with other nearby ships, AIS base stations and satellites. It is an important system for safety of navigation to assist collision avoidance and enables marine traffic supervision and management. However, the expanding use of AIS...
We consider the design of a reduced-rank minimum mean-squared error (MMSE) receiver for asynchronous multicarrier-direct sequence-code division multiple access (MC-DS-CDMA) systems with random spreading. We focus on the asymptotic MMSE filter designs in the large system regime, i.e., both the spreading gain and the number of users approach infinity while their ratio is a finite constant and the number...
This paper presents a new M-estimator based robust multi-user detection technique in asynchronous direct sequence-code division multiple access systems over Nakagami-m fading channels with impulsive noise. A new M-estimator, which performs well in the heavy-tailed impulsive noise, is proposed and analyzed for robustifying the detector. Average probability of error is derived and the performance of...
Although user cooperation improves sensing accuracy, a large number of secondary users (SUs) reporting decisions may cause significant overhead. In this paper, we propose a distributed scheme, called adaptive cooperative sensing (ACS), to reduce the sensing overhead while satisfying sensing accuracy requirements. In ACS, an anchor SU requires cooperative sensing only when it does not detect the presence...
In this paper, the performance of cooperative spectrum sensing with multiple antennas at each cognitive radio (CR) has been assessed in both Hoyt faded and non-faded (additive white Gaussian noise) environments. The CRs which employ improved energy detector (IED) utilize selection combining (SC) of the decision statistics obtained by IEDs for making hard decisions about the presence or absence of...
In Cognitive Radio (CR) networks, multiple secondary network users (SUs) attempt to communicate over wide potential spectrum without causing significant interference to the Primary Users (PUs). A spectrum sensing algorithm is a critical component of any sensing strategy. Performance of conventional spectrum detection methods is severely limited when the average SNR of the fading channel between the...
In this paper, performance of the energy detector is analyzed in blind cooperative relay networks operating over independent and identically distributed (IID) Rayleigh fading channels. First, utilizing the closed-form expression of the probability density function (PDF) of the dual-hop relay link along with an alternative series form representation of the generalized marcum-Q function, exact average...
In this paper, we analyze the performance of an energy detector operating over Gamma shadowed Rice fading channels, namely Rice fading channels with the fluctuating line-of-sight components following the Gamma distribution. This composite multi-path/shadowing model has been shown to provide remarkably accurate fading characterization while leading to closed-form expressions for important channel statistics...
This paper explores how iterative channel estimation, symbol detection and decoding at the receiver affects the achievable capacity compared with a non-iterative, purely pilots-based scheme. First, a bound is put on the linear minimum mean-square error (LMMSE) estimator of doubly selective radio channels. Subsequently, a bound on the capacity using an LMMSE estimator is found. These bounds take into...
Machine-to-Machine (M2M) wireless communication requires the transmission of short blocks of data with high reliability over fading channels. We discuss the use of the probabilistic data association (PDA) detector in conjunction with precoding to design high-performance systems for these links. First, the performance of the traditional PDA algorithm with precoding over ideal Rayleigh fading links...
A Middleton Class-A (MCA) model is one of the most accurate statistical-physical models for narrowband impulse noise. The previous studies show that time diversity can efficiently be used to reduce the impact of MCA noise. The optimum combiner in such noise consists of a nonlinear preprocessor followed by a conventional combiner. Since an MCA noise process consists of an infinite number of noise states,...
In this paper we consider an overlay cognitive network in which to guarantee a Quality of Service (QoS) for the primary users, a maximum probability of collision is enforced to secondary service. When collision, caused by imperfect spectrum sensing, happens, it results in increasing error rate in both primary and secondary systems. While such degradation in primary service conforms with QoS requirements...
In this work, we studied the effect of multi-user and multipath, on the performance of a serial acquisition search system, using adaptive threshold with constant false alarm rate, in Rayleigh fading channels. Since the received signal levels in mobile communications are unknown and location varying, the acquisition schemes for pseudo-noise (PN) sequences with fixed thresholds may cause too many false...
In this paper, we address the problem of delay detection for mobile localization in a multipath Rayleigh fading channel. A new methodology for delay detection, in presence of closely spaced interfering paths, is introduced, namely the Order-Statistics Minimum Error Rate (OS-MER) detector. The latter is based on the minimization of the error probability instead of minimizing only the miss probability...
In this paper, an iterative and computationally efficient data detection algorithm is proposed based on the space alternating generalized expectation maximization (SAGE) technique for orthogonal division multiplexing (OFDM) systems under fast fading channels. The proposed detector includes the original detector presented in [1] as one of its special cases. With a proper choice of its parameters, simulations...
Cooperative (spectrum) sensing is a key function for dynamic spectrum access and is essential for avoiding interference with licensed primary users and identifying spectrum holes. A promising approach for effective cooperative sensing over a large geographic region is to rely on special spectrum-sensing providers (SSPs), which outsource spectrum-sensing tasks to distributed mobile users. Its feasibility...
In this paper, performance of cooperative spectrum sensing (CSS) with likelihood ratio test (LRT) fusion at fusion center (FC) has been assessed in the presence of Rayleigh fading. Improved energy detector (IED) with multiple antennas has been used at each cognitive radio (CR) user where selection combining (SC) of decisions received from multiple antennas. Censoring of CR users has been considered...
This paper proposes an efficient design strategy for sequential detectors to reliably detect primary user's signals, especially in a fast fading scenario. We study computation of the log-likelihood ratio for coping with fast changing sample variances of received signal and noise, which are considered random variables. First, we analyze the detectability of the conventional generalized log-likelihood...
In this paper, we propose a generalized likelihood ratio test (GLRT)-based algorithm to detect the interference encountered in slow frequency-hopped 16-ary quadrature amplitude modulation (FH/16-QAM) systems. Both multitone interference (MTI) and partial-band noise interference (PBNI) are considered. By using the GLRT for the linear model, we derive the close-form expression for the test statistic...
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