Showing papers on "Fading distribution published in 2010"
TL;DR: The approach introduced in this paper can be used to well-approximate the distribution of the sum of independent generalized-K random variables by a gamma distribution; the need for such results arises in various emerging distributed communication technologies and systems such as coordinated multipoint transmission and reception schemes.
Abstract: In wireless channels, multipath fading and shadowing occur simultaneously leading to the phenomenon referred to as composite fading. The use of the Nakagami probability density function (PDF) to model multipath fading and the Gamma PDF to model shadowing has led to the generalized-K model for composite fading. However, further derivations using the generalized K PDF are quite involved due to the computational and analytical difficulties associated with the arising special functions. In this paper, the approximation of the generalized-K PDF by a Gamma PDF using the moment matching method is explored. Subsequently, an adjustable form of the expressions obtained by matching the first two positive moments, to overcome the arising numerical and/or analytical limitations of higher order moment matching, is proposed. The optimal values of the adjustment factor for different integer and non-integer values of the multipath fading and shadowing parameters are given. Moreover, the approach introduced in this paper can be used to well-approximate the distribution of the sum of independent generalized-K random variables by a gamma distribution; the need for such results arises in various emerging distributed communication technologies and systems such as coordinated multipoint transmission and reception schemes including distributed antenna systems and cooperative relay networks.
209 citations
TL;DR: In this article, the performance of a Nt x 1 MISO system setup with maximum likelihood (ML) detection and full CSI at the receiver is analyzed in closed-form.
Abstract: In this paper, we offer an accurate framework for analyzing the performance of wireless communication systems adopting the recently proposed Space Shift Keying (SSK) modulation scheme. More specifically, we study the performance of a Nt x 1 MISO (Multiple-Input-Single-Output) system setup with Maximum-Likelihood (ML) detection and full Channel State Information (CSI) at the receiver. The exact Average Bit Error Probability (ABEP) over generically correlated and non-identically distributed Nakagami-m fading channels is computed in closed-form when Nt=2, while very accurate and asymptotically tight upper bounds are proposed to compute the ABEP when Nt > 2. With respect to current literature, our contribution is threefold: i) the ABEP is computed in closed-form without resorting to Monte Carlo numerical simulations, which, besides being computationally intensive, only yield limited insights about the system performance and cannot be exploited for a systematic optimization of it, ii) the framework accounts for arbitrary fading conditions and is not restricted to identically distributed fading channels, thus offering a comprehensive understanding of the performance of SSK modulation over generalized fading channels, and iii) the analytical framework could be readily adapted to study the performance over generalized fading channels with arbitrary fading distributions, since the Nakagami-m distribution is a very flexible fading model, which either includes or can closely approximate several other fading models. Numerical results show that the performance of SSK modulation is significantly affected by the characteristics of fading channels, {e.g.}, channel correlation, fading severity, and power imbalance among the Nt transmit-receive wireless links. Analytical frameworks and theoretical findings are also substantiated via Monte Carlo simulations.
171 citations
TL;DR: Measurements and models of 30 narrowband multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V2V) radio propagation channels at 5.3 GHz found the large-scale fading was found to be lognormally distributed, whereas the small-scale fades was characterized by the flexible Weibull distribution.
Abstract: In this paper, we describe measurements and models of 30 t 30 narrowband multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V2V) radio propagation channels at 5.3 GHz. Four environments were considered: a campus, a highway, a suburban area, and an urban area. Since the scattering environment may rapidly change in V2V communications, we first investigate the validity of the wide-sense stationarity (WSS) assumption for such channels using the correlation matrix distance (CMD), which is a metric for the characterization of the MIMO channel nonstationarity. Moreover, statistical channel models were developed for these environments, which take into account the non-stationary behavior of the measured V2V channels. The large-scale fading was found to be lognormally distributed, whereas the small-scale fading was characterized by the flexible Weibull distribution. Finally, the non-stationary behavior of both large-scale fading and small-scale fading statistics was investigated.
131 citations
TL;DR: It is established that the overhead optimization for multiantenna systems is effectively the same as for single-antenna systems with the normalized Doppler frequency multiplied by the number of transmit antennas.
Abstract: The optimization of the pilot overhead in single-user wireless fading channels is investigated, and the dependence of this overhead on various system parameters of interest (e.g., fading rate, signal-to-noise ratio) is quantified. The achievable pilot-based spectral efficiency is expanded with respect to the fading rate about the no-fading point, which leads to an accurate order expansion for the pilot overhead. This expansion identifies that the pilot overhead, as well as the spectral efficiency penalty with respect to a reference system with genie-aided CSI (channel state information) at the receiver, depend on the square root of the normalized Doppler frequency. It is also shown that the widely-used block fading model is a special case of more accurate continuous fading models in terms of the achievable pilot-based spectral efficiency. Furthermore, it is established that the overhead optimization for multiantenna systems is effectively the same as for single-antenna systems with the normalized Doppler frequency multiplied by the number of transmit antennas.
119 citations
TL;DR: This model includes several new aspects in this model that are specific to multiuser distributed channels: correlated shadowing between different point-to-point links, which has a strong impact on cooperative system performance; different types of indoor node mobility with respect to the transmitter and/or receiver nodes.
Abstract: We propose and parameterize an empirical model of the outdoor-to-indoor and indoor-to-indoor distributed (cooperative) radio channel, using experimental data in the 2.4-GHz band. In addition to the well-known physical effects of path loss, shadowing, and fading, we include several new aspects in our model that are specific to multiuser distributed channels: 1) correlated shadowing between different point-to-point links, which has a strong impact on cooperative system performance; 2) different types of indoor node mobility with respect to the transmitter and/or receiver nodes, implying a distinction between static and dynamic shadowing motivated by the measurement data; and 3) a small-scale fading distribution that captures more severe fading than that given by the Rayleigh distribution.
113 citations
TL;DR: An approximation of the average probability of detection over a slow fading channel is derived by replacing the log-normal distribution with a Wald distribution and analyzing the detection performance of the ED using a square-law combining scheme over multiple independent and identically distributed slow fading channels.
Abstract: Energy detection (ED) has been widely used for detecting unknown deterministic signals in many wireless communication applications, e.g., cognitive radio, and ultra-wideband (UWB). However, the performance analysis of ED over slow fading channels is cumbersome, because it is difficult to derive closed-form expressions for the average probability of detection involving the generalised Marcum Q-function and the log-normal distribution. In this letter, we derive an approximation of the average probability of detection over a slow fading channel by replacing the log-normal distribution with a Wald distribution. In addition, we analyze the detection performance of the ED using a square-law combining scheme over multiple independent and identically distributed slow fading channels.
101 citations
TL;DR: A thorough and exact analysis is conducted to analyze the outage probability of MRNs under dissimilar Nakagami-m fading conditions, which highlights the performance improvements offered by opportunistic scheduling and reveals the impact of the relay location with unbalanced hops on the overall performance.
Abstract: We evaluate the performance of downlink multiuser relay networks (MRNs) equipped with a single amplify-and-forward (AaF) relay. A thorough and exact analysis is conducted to analyze the outage probability of MRNs under dissimilar Nakagami-m fading conditions. More specifically, we derive new closed-form expressions for the outage probability and the probability density function (pdf) of the highest end-to-end signal-to-noise ratio (SNR) associated with the strongest destination with the single user and Rayleigh fading as special cases. In particular, we provide new results for channel-state information (CSI)-based-gain relaying and fixed-gain relaying. We then demonstrate that the achievable diversity order is equal to either the first-hop fading parameter or the product of the second-hop fading parameter and the number of destinations. Furthermore, we derive compact closed-form expressions for the moments of the highest end-to-end SNR, from which other moment-based measures such as the average SNR and the amount of fading are deduced. Our results highlight the performance improvements offered by opportunistic scheduling and reveal the impact of the relay location with unbalanced hops on the overall performance. Various numerical examples illustrate the proposed analysis.
100 citations
12 Apr 2010
TL;DR: Novel methodologies are presented which allow robust secret key extraction from radio channel measurements which suffer from real-world non-reciprocities and a priori unknown fading statistics and produce secret key bits at a higher rate than has previously been reported.
Abstract: This paper presents novel methodologies which allow robust secret key extraction from radio channel measurements which suffer from real-world non-reciprocities and a priori unknown fading statistics. These methodologies have low computational complexity, automatically adapt to differences in transmitter and receiver hardware, fading distribution and temporal correlations of the fading signal to produce secret keys with uncorrelated bits. Moreover, the introduced method produces secret key bits at a higher rate than has previously been reported. We validate the method using extensive measurements between TelosB wireless sensors.
98 citations
09 Nov 2010
TL;DR: The most general composite fading distribution is introduced to model the envelope and the power of the received signal in such fading channels as millimeter wave (60 GHz or above) fading channels and free-space optical channels, which is term extended generalized-K (EGK) composite fade distribution.
Abstract: In this paper, we introduce the most general composite fading distribution to model the envelope and the power of the received signal in such fading channels as millimeter wave (60 GHz or above) fading channels and free-space optical channels, which we term extended generalized-K (EGK) composite fading distribution. We obtain the second-order statistics of the received signal envelope characterized by the EGK composite fading distribution. Expressions for probability density function, cumulative distribution function, level crossing rate and average fade duration, moments, amount of fading and average capacity are derived. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis.
96 citations
TL;DR: It is proved that the gap with its Lagrange dual problem is zero, so long as the underlying fading distribution function is continuous, which means separating the design of wireless networks in layers and per-fading state subproblems can be optimal.
Abstract: A general wireless networking problem is formulated whereby end-to-end user rates, routes, link capacities, transmit-power, frequency, and power resources are jointly optimized across fading states. Even though the resultant optimization problem is generally nonconvex, it is proved that the gap with its Lagrange dual problem is zero, so long as the underlying fading distribution function is continuous. The major implication is that separating the design of wireless networks in layers and per-fading state subproblems can be optimal. Subgradient descent algorithms are further developed to effect an optimal separation in layers and layer interfaces.
88 citations
TL;DR: Analytical closed-form expressions for the cyclic cumulant polyspectra of linearly digitally modulated signals affected by fading, carrier frequency and timing offsets, and additive Gaussian noise are derived, along with a condition for the oversampling factor to avoid aliasing in the cycle and spectral frequency domains.
Abstract: Modulation classification is an intermediate step between signal detection and demodulation, and plays a key role in various civilian and military applications. In this correspondence, higher-order cyclic cumulants (CCs) are explored to discriminate linear digital modulations in flat fading channels. Single- and multi-antenna CC-based classifiers are investigated. These benefit from the robustness of the CC-based features to unknown phase and timing offset. Furthermore, the latter provides significant performance improvement due to spatial diversity used to combat the fading effect. Classifier performances are investigated under a variety of channel conditions. In addition, analytical closed-form expressions for the cyclic cumulant polyspectra of linearly digitally modulated signals affected by fading, carrier frequency and timing offsets, and additive Gaussian noise are derived, along with a condition for the oversampling factor to avoid aliasing in the cycle and spectral frequency domains.
TL;DR: A very accurate analytical framework for the analysis and optimization of this novel detector over generically correlated and non-identically distributed Nakagami-{m} fading channels is proposed, and its performance compared to the optimal receiver design with F-CSI is proposed.
Abstract: Space Shift Keying (SSK) modulation is a new and recently proposed transmission technology for Multiple-Input-Multiple-Output (MIMO) wireless systems, which has been shown to be a promising low-complexity alternative to several state-of-the-art MIMO schemes. So far, only optimal or heuristic transceivers with Full Channel State Information (F-CSI) at the receiver have been investigated, and their performance analyzed over fading channels. In this paper, we develop and study the performance of the optimal Maximum-Likelihood (ML) detector with unknown phase reference at the receiver (i.e., Partial-CSI, P-CSI, knowledge). A very accurate analytical framework for the analysis and optimization of this novel detector over generically correlated and non-identically distributed Nakagami-{m} fading channels is proposed, and its performance compared to the optimal receiver design with F-CSI. Numerical results will point out that: i) the performance of SSK modulation is significantly affected by the characteristics of fading channels, e.g., channel correlation, fading severity, and, particularly, power imbalance among the transmit-receive wireless links, and ii) unlike ordinary modulation schemes, there is a substantial performance loss when the receiver cannot exploit the phase information for optimal receiver design. This latter result highlights the importance of accurate and reliable channel estimation mechanisms for the efficient operation of SSK modulation over fading channels. Analytical frameworks and theoretical findings will also be substantiated via Monte Carlo simulations.
TL;DR: The results in this Letter are applicable to the OP analysis of maximal ratio combining (MRC) over i.i.d. η-μ or Hoyt fading channels.
Abstract: In this Letter we derive exact closed-form expressions for the outage probability (OP) in η-μ fading channels. First, a general expression in terms of the confluent Lauricella function is derived for arbitrary values of μ. Next, we restrict the analysis to physical η-μ channel models, i.e. to integer values of 2μ, and obtain exact closed-form expressions for the OP in terms of Marcum Q, Bessel and elementary functions. The results in this Letter are applicable to the OP analysis of maximal ratio combining (MRC) over i.i.d. η-μ or Hoyt fading channels.
TL;DR: In this paper, a number of propagation measurements of belt to head and belt-to-wrist channels have been performed with inverted F-antennas, PIFAs, monopole, loop and dipole antennas, and propagation models were derived.
Abstract: A number of propagation measurements of belt-to-head and belt-to-wrist channels have been performed with inverted F-antennas, planar inverted F-antennas (PIFAs), monopole, loop and dipole antennas, and propagation models were derived. It is found that the channel can be separated into short-term and long-term fading components. The short-term fading can generally be modelled with a Rician distribution, whereas in many cases, long-term fading is lognormal, the best distribution is dependent on the channel, antenna type and orientation. Variation of channel parameters with time is studied and an alternative approach to modelling long-term fading deterministically is suggested. Power spectral densities, autocorrelation functions, fade probabilities, level crossing rates and average fade durations are also investigated.
TL;DR: This paper theoretically investigates the signal degradation induced by intersubcarrier interference and frequency-selective fading in orthogonal frequency-division-multiplexing radio-over-fiber systems and proposes Turbo codes and bit interleaver technologies to effectively mitigate unbalanced error distribution.
Abstract: This paper theoretically investigates the signal degradation induced by intersubcarrier interference and frequency-selective fading in orthogonal frequency-division-multiplexing radio-over-fiber systems. Turbo codes and bit interleaver technologies are proposed to effectively mitigate unbalanced error distribution because of intersubcarrier interference and frequency-selective fading. Experimental results show that the receiver sensitivities are improved as far as 5 dB after 50-km SMF-28 transmission for 6.25-Gb/s wireless signals on optical generated 60-GHz carrier.
TL;DR: The capacity of single-user discrete-time channels subject to both frequency-selective and time- selective fading, where the channel output is observed in additive Gaussian noise is found.
Abstract: This paper finds the capacity of single-user discrete-time channels subject to both frequency-selective and time-selective fading, where the channel output is observed in additive Gaussian noise. A coherent model is assumed where the fading coefficients are known at the receiver. Capacity depends on the first-order distributions of the fading processes in frequency and in time, which are assumed to be independent of each other, and a simple formula is given when one of the processes is independent identically distributed (i.i.d.) and the other one is sufficiently mixing. When the frequency-selective fading coefficients are known also to the transmitter, we show that the optimum normalized power spectral density is the waterfilling power allocation for a reduced signal-to-noise ratio (SNR), where the gap to the actual SNR depends on the fading distributions. Asymptotic expressions for high/low SNR and easily computable bounds on capacity are also provided.
30 Sep 2010
TL;DR: Considering the outage probability for Rayleigh fading, L-PSK with large L shows the best performance among conventional modulation schemes, and circular symmetry with at most one amplitude per phase is a necessary condition for optimal modulation.
Abstract: The achievable rate of communications systems depends on the quantization resolution at the receiver. Earlier work has shown that the capacity of real-valued AWGN channels with 1-bit output quantization is achieved with BPSK. This paper studies optimal modulation schemes, the ergodic capacity and the outage probability for complex-valued fading channels with 1-bit output quantization, assuming full channel knowledge at the receiver. It is shown that circular symmetry with at most one amplitude per phase is a necessary condition for optimal modulation. Circular-symmetric PSK achieves the ergodic capacity in case of Rayleigh fading. Considering the outage probability for Rayleigh fading, L-PSK with large L shows the best performance among conventional modulation schemes.
TL;DR: It is shown in theoretical analysis and simulation that the error output of the tracking loop can be approximated to a Gaussian distribution and there is close agreement between the derived analytical upper bound results in the presence of fading and the simulation results.
TL;DR: An analytical capacity bound is derived which is applicable for arbitrary values of the signal-to-noise ratio (SNR) and number of antenna elements and deduce simple bound approximations in the high-SNR regime and demonstrate that the effects of small and large-scale fading are decoupled.
Abstract: This correspondence explores the ergodic capacity of multiple-input multiple-output (MIMO) systems operating in generalized- K fading conditions. Using some recent results on majorization theory, we derive an analytical capacity bound which is applicable for arbitrary values of the signal-to-noise ratio (SNR) and number of antenna elements. In addition, we deduce simple bound approximations in the high-SNR regime and demonstrate that the effects of small and large-scale fading are decoupled. A similar statistical analysis is carried out for MIMO channels under K-fading, which represents a special case of generalized-K fading that can be tackled via the Wishart matrix theory. The implications of the model parameters on the bound performance are also investigated via Monte Carlo simulations.
29 Nov 2010
TL;DR: By applying for the first time an accurate empirical mean path loss propagation model along with a well fitted fading distribution model specifically defined for the tunnel environment, this paper addresses the RN placement problem with guaranteed levels of radio link performance.
Abstract: Node placement plays a significant role in the effective and successful deployment of Wireless Sensor Networks (WSNs), i.e., meeting design goals such as cost effectiveness, coverage, connectivity, lifetime and data latency. In this paper, we propose a new strategy to assist in the placement of Relay Nodes (RNs) for a WSN monitoring underground tunnel infrastructure. By applying for the first time an accurate empirical mean path loss propagation model along with a well fitted fading distribution model specifically defined for the tunnel environment, we address the RN placement problem with guaranteed levels of radio link performance. The simulation results show that the choice of appropriate path loss model and fading distribution model for a typical environment is vital in the determination of the number and the positions of RNs. Furthermore, we adapt a two-tier clustering multi-hop framework in which the first tier of the RN placement is modelled as the minimum set cover problem, and the second tier placement is solved using the search-and-find algorithm. The implementation of the proposed scheme is evaluated by simulation, and it lays the foundations for further work in WSN planning for underground tunnel applications.
TL;DR: Numerical results show that, for a signal having a Nakagami-m distributed fading envelope, the proposed model closely approximates the distributions of the real and imaginary parts of signals with Rician and Hoyt fading envelopes for 1 <; m<; ∞ and 1/2 ≤ m <; 1, respectively, as well as the distributionsof the corresponding phases.
Abstract: The Nakagami-m distribution approximates a Rician distribution for the fading parameter m in the range 1 <; m <; ∞, and approximates a Hoyt or Nakagami-q distribution for m in the range 1/2 ≤ m <; 1, while it becomes a Rayleigh distribution for m=1. A uniformly distributed phase for all m ≥ 1/2 does not satisfy all these requirements. By using the distributions of the real and imaginary parts of complex fading gains having Rician and Hoyt distributed envelopes, we propose in this paper a new statistical model of the complex Nakagam-m fading gain for which the envelope has a Nakagami-m distribution and the phase has a nonuniform distribution. Numerical results show that, for a signal having a Nakagami-m distributed fading envelope, the proposed model closely approximates the distributions of the real and imaginary parts of signals with Rician and Hoyt fading envelopes for 1 <; m <; ∞ and 1/2 ≤ m <; 1, respectively, as well as the distributions of the corresponding phases.
18 Apr 2010
TL;DR: A simple and new form of distribution which can accurately represent both the mutlipath fading and shadowing effects is introduced and the signal-to-noise ratio (SNR) follows the gamma-lognormal distribution, which is accurately approximated by a weighted mixture of gamma distributions.
Abstract: The Nakagami-lognormal distribution is the commonly used composite distribution for modeling multipath fading and shadowing. In this paper, simple and new form of distribution which can accurately represent both the mutlipath fading and shadowing effects is introduced. The signal-to-noise ratio (SNR) of the Nakagami-lognormal distribution follows the gamma-lognormal distribution, which is accurately approximated by a weighted mixture of gamma distributions. We show how the weights and other parameters of the summands are obtained. Further, accuracy of the mixture distribution is compared with the $K_G$ distribution -- a popular approximation of the Nakagami-lognormal distribution.
19 Jun 2010
TL;DR: In this paper, Monte-Carlo simulation results for the bit error rate (BER) performance and the fading penalty of a BPSK -subcarrier intensity modulation (BPSK-SIM) free-space optical (FSO) communication link in a log-normal atmospheric turbulence model are presented.
Abstract: In this paper, we present simulation results for the bit error rate (BER) performance and the fading penalty of a BPSK - subcarrier intensity modulation (BPSK-SIM) free-space optical (FSO) communication link in a log-normal atmospheric turbulence model. The results obtained are based on the Monte-Carlo simulation. Multiple subcarrier modulation schemes offer increased system throughput and require no knowledge of the channel fading in deciding what symbol has been received. In an atmospheric channel with a fading strength σ² of 0.1 obtaining a BER of 10E-6 using a 2-subcarrier system will require a signal-to-noise (SNR) of 23.1 dB. The required SNR increases with the fading strength and at a BER of 10E-9 the fading penalty due to the atmospheric turbulence is ~ 41 dB for σ²=0.9. The comparative studies of the OOK and BPSK-SIM schemes showed that for similar electrical SNR, BPSK-SIM offered improved performance across all range of turbulence variance.
TL;DR: The probability that the "low interference regime" holds under shadow fading as well as Rayleigh and Rician fast fading conditions is derived and the use of the approximation is shown to be extremely accurate.
Abstract: In this paper we consider the capacity of the cognitive radio (CR) channel in different fading environments under a "low interference regime". First we derive the probability that the "low interference regime" holds under shadow fading as well as Rayleigh and Rician fast fading conditions. We demonstrate that this is the dominant case, especially in certain practical CR deployment scenarios. The capacity of the CR channel depends critically on a power loss parameter, ?, which governs how much transmit power the CR dedicates to relaying the primary message. We derive a simple, accurate approximation to ? in Rayleigh and Rician fading environments which gives considerable insight into system capacity. We also investigate the effects of system parameters and propagation environment on ? and the CR capacity. In all cases, the use of the approximation is shown to be extremely accurate.
TL;DR: A versatile fading distribution that generalises many commonly used models for multi-path and shadow fading is the so-called generalised-K (KG) distribution, which is derived by considering the product of N independent but not necessarily identically distributed squared KG random variables (RVs).
Abstract: A versatile fading distribution that generalises many commonly used models for multi-path and shadow fading is the so-called generalised-K (KG) distribution. By considering the product of N independent but not necessarily identically distributed (n.i.d.) squared KG random variables (RVs), we derive exact closed-form expressions for the moment generating function, probability density function, cumulative distribution function and the moments of the cascaded KG fading channel. Expressions for the ergodic capacity and the error performance of different digital modulation schemes are also obtained. Based on the above mentioned formulas, we analyse the performance of orthogonal space-time block codes over multiple-input multiple-output keyhole KG fading channels. Various performance evaluation results demonstrate the proposed mathematical analysis.
01 Dec 2010
TL;DR: This paper study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio Combining (MRC) diversity at the secondary receiver under asymmetric fading, where the channel from secondary transmitter to primary receiver suffer Nakagami-m fading while the one fromsecondary transmitter to its receiver follows Rayleigh Multipath fading.
Abstract: In this paper we study the capacity of spectrum sharing cognitive radios (CR) with Maximal Ratio Combining (MRC) diversity at the secondary receiver under asymmetric fading, where the channel from secondary transmitter to primary receiver suffer Nakagami-m fading while the one from secondary transmitter to its receiver follows Rayleigh Multipath fading. Our mathematical analysis and numerical results show that with MRC combining diversity at the secondary receiver, more capacity is achieved. In addition, when the SU$_{tx}$-PU$_{rx}$ channel has less severe fading which strongly affects the capacity of CR channel, utilizing MRC combining technique for CR system could reduce the effects.
TL;DR: Novel closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF) and the moments of this bounded SNR are derived and can be afterwards used to obtain important performance metrics of the considered system such as the outage probability and the error performance of digital modulation schemes.
Abstract: In this paper, a study on the end-to-end performance of dual-hop non-regenerative relaying over independent generalized-K (KG) fading channels is presented Using a suitable upper bound for the end-to-end signal-to-noise ratio (SNR), novel closed-form expressions for the cumulative distribution function (CDF), probability density function (PDF) and the moments of this bounded SNR are derived These results can be afterwards used to obtain important performance metrics of the considered system such as the outage probability and the error performance of digital modulation schemes In the case of independent but non-necessarily identical fading channels, lower bounds for the average bit error probability (ABEP) for different modulation schemes are determined by using the Pade approximants method For the case of identical fading channels, closed-form lower bounds for the ABEP are derived Various numerical and computer simulation results illustrate the proposed analysis
TL;DR: The analytical expressions are used to investigate the impact of different fading parameters of this composite fading channel model on the average bit error rate performance for a variety of digital modulation schemes and the spectral efficiency of different adaptive transmission policies.
Abstract: In the present study, the performance of digital communication systems operating over a composite fading channel modelled by the generalised-K distribution is analysed and evaluated. Novel closed-form expressions for the outage performance, the average bit error probabilities of several modulation schemes and the channel capacity under four different adaptive transmission schemes are derived. The analytical expressions are used to investigate the impact of different fading parameters of this composite fading channel model on the average bit error rate performance for a variety of digital modulation schemes and the spectral efficiency of different adaptive transmission policies.
TL;DR: Stochastic resource allocation schemes are developed which are capable of dynamically learning the intended wireless channels and converging to the optimal benchmark without a priori knowledge of channel fading distribution function.
Abstract: In this paper we consider the energy-efficient resource allocation that minimizes a general cost function of average user powers for small- or medium-scale wireless sensor networks, where the simple time-division multiple-access (TDMA) is adopted as the multiple access scheme. A class of so-called s-fair cost functions is derived to balance the tradeoff between efficiency and fairness in energy-efficient designs. Based on such cost functions, optimal channel-adaptive resource allocation schemes are developed for both single-hop and multihop TDMA sensor networks. Relying on stochastic optimization tools, we further develop stochastic resource allocation schemes which are capable of dynamically learning the intended wireless channels and converging to the optimal benchmark without a priori knowledge of channel fading distribution function.
TL;DR: A simple non-coherent amplify-and-forward receiver for the relay channel and its diversity performance for Rayleigh fading channels is evaluated, with the probability of error decreasing with increasing signal-to-noise ratio (SNR) as log2(SNR)/ SNR2 for large SNR.
Abstract: This paper proposes a simple non-coherent amplify-and-forward receiver for the relay channel and evaluates its diversity performance for Rayleigh fading channels. We use the generalized likelihood ratio test to obtain the decision rule in closed form, independent of the fading distribution. The receiver is developed for M-ary orthogonal signals and multiple relays. The only side information required at the destination is the average noise energy at the receiver; no statistical knowledge of the channel gains is needed. We develop closed-form upper and lower bounds on the probability of error of this receiver for the case of binary signaling with a single relay and show that this receiver achieves near full diversity, with the probability of error decreasing with increasing signal-to-noise ratio (SNR) as log2(SNR)/ SNR2 for large SNR. Additional results obtained by simulation demonstrate increasing diversity gain with additional relays.