Two-wave With Diffuse Power Research Articles

Performance of M-ary PSK over TWDP fading channels

ABSTRACTPerformance of M-ary phase shift keying (MPSK) is analysed in two-wave with diffuse power (TWDP) fading channel. The TWDP channel is characterised by two specular waves along with the diffuse power and has both Rayleigh and Rician fading distributions as special cases. Closed-form expression for the bit error rate (BER) of MPSK (M > 4) in TWDP fading is derived using Chiani approximation for the complimentary error function. Numerical results show excellent agreement with the simulation results.

Performance analysis of opportunistic amplify-and-forward two-way relaying in two-wave with diffuse power fading channels

This paper considers cooperative amplify-and-forwards (AF) two-way relay networks (TWRNs) with opportunistic relay selection (ORS) in two-wave with diffuse power (TWDP) fading channels. To investigate the system performance, we first derive an easy-to-computer approximated expression for the exact outage probability to reduce computational cost. Furthermore, we presented compact expressions for the asymptotic outage probability and asymptotic symbol error rate, which characterizes two factors governing the network performance at high signal-to-noise ratio (SNR) in terms of diversity order and coding gain. Additionally, based on the asymptotic outage probability, we determine the optimal power allocation solution between the relay and the sources to minimize the overall outage probability under the assumption that both the sources have identical transmit power. The correctness of the analysis is validated through Monte Carlo simulations. Our derived results can be applied to general operating scenarios with distinct TWDP fading parameters which encompass Rayleigh and Rician fading as special cases and arbitrary number of relays.

Performance analysis of energy detection over hyper‐Rayleigh fading channels

This study investigates the performance of energy detection (ED)-based spectrum sensing over two-wave with diffused power (TWDP) fading channels, which have been found to provide accurate characterisation for a variety of fading conditions. A closed-form expression for the average detection probability of ED-based spectrum sensing over TWDP fading channels is derived. This expression is then used to describe the behaviour of ED-based spectrum sensing for a variety of channels that include Rayleigh, Rician and hyper-Rayleigh fading models. Such fading scenarios present a reliable behavioural model of machine-to-machine wireless nodes operating in confined structures such as in-vehicular environments.

Performance of SC Receiver over TWDP Fading Channels

Performance of selection combining (SC) receiver has been derived over two-wave diffused power (TWDP) fading channels with arbitrary and non-identical fading parameters. An expression of cumulative distribution function (CDF) of signal-to-noise ratio (SNR) for TWDP fading channel has been derived, which is used to obtain the probability density function (PDF) of SNR at the output of SC receiver. The PDF of output SNR has been used to derive expressions of outage probability and average bit error rate for coherent and non-coherent modulation schemes. Effect of total number of branches M and the fading parameters K and Δ on the system performance has been studied. The obtained results are verified with the special case results available in literature and by Monte Carlo simulation.

Performance of QAM Signaling over TWDP Fading Channels

Performance of quadrature amplitude modulation (QAM) scheme in two-wave with diffuse power (TWDP) fading environment is analyzed. Closed-form expressions for the exact average symbol error rate (ASER) of general order rectangular QAM (RQAM) and cross QAM (XQAM) schemes are presented using moment generating function of TWDP fading distribution. Obtained ASER expressions are in the form of Appell's (Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> (·)) and Lauricella's (Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">(3)</sup> (·)) hypergeometric functions which can be numerically evaluated using either integral or series representation. Further, closed-form expression for the nth order moment of the received signal-to-noise ratio is derived. Numerical results show excellent agreement with simulation results.

On the Connectivity of 2-D Random Networks with Anisotropically Radiating Nodes

We study the effect that anisotropic radiation has on the probability that a dense, two-dimensional (2-D) random network is fully connected. To this end, we provide a thorough analytical treatment of the connectivity of wireless ad hoc networks with beamforming using a newly established theory of connectivity reported in , where we assume the network experiences small-scale fading according to the well-known two-wave with diffuse power (TWDP) model. We calculate the connectivity mass related to various radiation patterns, and show that isotropic radiation is optimal when the path loss exponent is greater than two, but single-sector directed transmission yields superior performance for other cases. We exploit our analysis to design optimal radiation patterns in the sense that connectivity is maximized, which can be used as masks to perform antenna pattern synthesis. Our results exhibit a property of universality with respect to the small-scale fading model since they do not depend on the TWDP fading parameters.

Symbol Error Rate of Decode-and-Forward Relaying in Two-Wave with Diffuse Power Fading Channels

We analyze the symbol error rate (SER) of selective decode-and-forward (DF) relaying for the practical case of independent but not necessarily identically distributed two-wave with diffuse power (TWDP) fading. We first derive new exact SER expressions with M-ary phase-shift keying and M-ary quadrature amplitude modulation. We then derive tight upper bounds on the exact SER in closed form to avoid the numerical integration involved in the exact results. Furthermore, we derive concise yet valuable expressions for the asymptotic SER, which characterizes the system behavior in the high signal-to-noise ratio (SNR) regime in terms of the diversity order and the coding gain. Based on the asymptotic SER, we confirm that TWDP fading parameters have no impact on the diversity order, but affect the coding gain. We also demonstrate that the contribution of the source-destination link to the SER is higher than that of the source-relay link or the relay-destination link. Our analytical results are valid for general operating scenarios with arbitrary average SNRs and distinct TWDP fading parameters in each hop.

Opportunistic Decode-and-Forward Relaying With Beamforming in Two-Wave With Diffuse Power Fading

In this paper, we propose new opportunistic decode-and-forward (DF) relaying with beamforming for multirelay networks, where an Ns-antenna source communicates with an Nd-antenna destination with the aid of N parallel single-antenna relays. Among these relays, only one relay that correctly decodes the signal from the source and has the highest instantaneous signal-to-noise ratio (SNR) to the destination is selected for transmission. The source employs maximum ratio transmission (MRT) to transmit, whereas the destination performs maximum ratio combining (MRC) to the received signals. To examine the benefits of the proposed scheme, we first derive the exact outage probability for independently but non-identically distributed (i.n.i.d.) two-wave with diffuse power (TWDP) fading channels. We then derive an easy-to-compute expression for the exact outage probability to reduce computational cost. Our results encompass Rayleigh and Rician fading as special cases. We further derive a compact expression for the asymptotic outage probability, which characterizes two factors governing the network performance at high SNRs, i.e., the diversity order and the array gain. We demonstrate that our scheme preserves the maximum diversity order of N × min {Ns, Nd}. Additionally, we derive the optimal power allocation factor, which provides a practical design rule to optimally distribute the total transmission power between the source and the selected relay to minimize the outage probability.

Analysis of switch diversity combining over two wave with diffuse power fading

The two wave with diffused power (TWDP) fading model is a very useful fading model characterised by two specular waves in the presence of other diffused waves and is applicable to both the Rayleigh and Rician fading channels as special cases. The performance of switch diversity with binary modulation schemes over the TWDP fading channel is examined. The four types of switch diversity investigated in this study comprise of the switch-and-stay combining, switch-and-examine combining, switch-and-examine combining with post-selection and scan-and-wait combining. The expressions of the average output signal-to-noise ratio (SNR) at the receiver and bit-error rate (BER) are derived and presented. The pre-determined SNR thresholds of the switch diversity over the TWDP fading channel are optimised to obtain the minimum BER. Analytical results are validated by simulation.

Outage Probability of Cooperative Relay Networks in Two-Wave with Diffuse Power Fading Channels

This paper analyzes the performance of cooperative relay networks using adaptive decode-and-forward (DF) relaying in two-wave with diffuse power (TWDP) fading channels. Among the multiple parallel relays that participate in transmission, only the relays that successfully decode the source message retransmit the signals to the destination. At the destination, the direct signals from the source and the indirect signals via the relays are combined using maximal-ratio combining (MRC). We first derive a new closed-form expression for the outage probability, which encompasses the Rayleigh fading and Rician fading as special cases. We then derive a tight lower bound on the outage probability to reduce computational complexity. The correctness of our derivation is validated through Monte Carlo simulations. It is shown that increasing the number of relays decreases the outage probability at high signal-to-noise ratio (SNR), but increases the outage probability at low to medium SNR.

Symbol Error Probability of QAM with MRC Diversity in Two-Wave with Diffuse Power Fading Channels

In the context of two-wave with diffuse power (TWDP) fading scenarios, this letter analyzes the average symbol error probability (SEP) of rectangular quadrature amplitude modulation (QAM) for single- and multi-channel receptions. Specifically, novel exact expressions are derived for the average SEP in nondiversity and maximal-ratio combining (MRC) schemes. Our derived SEP results apply to general operating scenarios with distinct TWDP fading parameters and arbitrary number of diversity branches.

Performance analysis of QAM in a two-wave with diffuse power fading environment

This letter investigates the average bit error rate (BER) performance of quadrature amplitude modulation in a two-wave with diffuse power (TWDP) fading environment. In TWDP fading, the received signal is composed of two specular components in addition to the diffuse component. The cumulative distribution function of TWDP fading is used to derive the BER expression in closed-form. Numerical and simulation results are presented to show the impact of different TWDP fading scenarios on the error performance.

Performance of BPSK Pre-detection MRC Systems over Two-Wave with Diffuse Power Fading Channels

The bit-error rate (BER) analysis for BPSK pre-detection maximal ratio combining (MRC) systems in two-wave with diffuse power (TWDP) fading is presented. In TWDP fading, the received signal is composed of two specular components in addition to the diffuse signal. The analysis shows that in TWDP fading, the BER of the MRC system is given by the weighted sum of the BERs of a number of MRC systems in Rician fading. The methodology used in the analysis is verified through simulation.

BER performance of BPSK receivers over two-wave with diffuse power fading channels

This letter presents the bit error rate (BER) performance analysis for an uncoded binary phase-shift keying (BPSK) system in two-wave with diffused power (TWDP) fading channels. Simulation results of receiver performance, with or without maximal-ratio combining (MRC), are also presented. These performance studies quantitatively reveal that TWDP fading can produce a link worse than Rayleigh fading when the two direct waves are equal in strength and have a combined power of /spl ges/ 6 dB higher than the diffused power. These results point to using TWDP fading rather than Rayleigh fading as a worst case scenario in designing communication systems, especially in situations where TWDP fading is likely, such as when directional antennas or arrays and when wideband signals are used.