Performance and Detection of M-ary Frequency Shift Keying in Triple Layer Wireless Sensor Network

This paper proposes an innovative triple layer Wireless Sensor Network (WSN) system, which monitors M-ary events like temperature, pressure, humidity, etc. with the help of geographically distributed sensors. The sensors convey signals to the fusion centre using M-ary Frequency Shift Keying (MFSK)modulation scheme over independent Rayleigh fading channels. At the fusion centre, detection takes place with the help of Selection Combining (SC) diversity scheme, which assures a simple and economical receiver circuitry. With the aid of various simulations, the performance and efficacy of the system has been analyzed by varying modulation levels, number of local sensors and probability of correct detection by the sensors. The study endeavors to prove that triple layer WSN system is an economical and dependable system capable of correct detection of M-ary events by integrating frequency diversity together with antenna diversity.Comment: 13 pages; International Journal of Computer Networks & Communications (IJCNC) Vol.4, No.4, July 201

Performance Analysis of Coherent and Noncoherent Modulation under I/Q Imbalance

In-phase/quadrature-phase Imbalance (IQI) is considered a major performance-limiting impairment in direct-conversion transceivers. Its effects become even more pronounced at higher carrier frequencies such as the millimeter-wave frequency bands being considered for 5G systems. In this paper, we quantify the effects of IQI on the performance of different modulation schemes under multipath fading channels. This is realized by developing a general framework for the symbol error rate (SER) analysis of coherent phase shift keying, noncoherent differential phase shift keying and noncoherent frequency shift keying under IQI effects. In this context, the moment generating function of the signal-to-interference-plus-noise-ratio is first derived for both single-carrier and multi-carrier systems suffering from transmitter (TX) IQI only, receiver (RX) IQI only and joint TX/RX IQI. Capitalizing on this, we derive analytic expressions for the SER of the different modulation schemes. These expressions are corroborated by comparisons with corresponding results from computer simulations and they provide insights into the dependence of IQI on the system parameters. We demonstrate that the effects of IQI differ considerably depending on the considered system as some cases of single-carrier transmission appear robust to IQI, whereas multi-carrier systems experiencing IQI at the RX require compensation in order to achieve a reliable communication link

Performance analysis of SWIPT relay networks with noncoherent modulation

In this paper, we investigate the performance of noncoherent modulation in simultaneous wireless information and power transfer (SWIPT) relay networks. Noncoherent modulation schemes eliminate the need for instantaneous channel state information (CSI) estimation, and therefore, minimise the overall energy consumption of the network. In particular, we adopt a moments-based approach to develop a comprehensive novel analytical framework for the analysis of the outage probability, achievable throughput, and average symbol error rate (ASER) of a dual-hop SWIPT relay system considering the time switching (TS) and power splitting (PS) receiver architectures. In addition, through the derivation of new asymptotic analytical results for the outage probability and ASER, we analytically demonstrate that the diversity order of the considered system is non-integer less than 1 in the high SNR regime. Our results show that there is a unique value for the PS ratio that minimises the outage probability of the system, while this is not the case for the TS protocol. We also demonstrate that, in terms of system throughput, the TS relaying scheme is superior to the PS relaying scheme at lower SNR values. An extensive Monte Carlo simulation study is presented to corroborate the proposed analytical model

Performance Analysis of Non-Ideal MIMO Systems in Fading Channels

En esta tesis se aborda el análisis de prestaciones de sistemas MIMO bajo ciertas condiciones no ideales. Se han considerado limitaciones realistas como son las interferencias co-canal, el canal de retorno con velocidad limitada, y la correlación espacial entre antenas. Bajo estas condiciones, se han analizado las probabilidades de error y de outage para sistemas MIMO que incluyen técnicas de conformación de haz en el transmisor y/o distintas técnicas de diversidad espacial en el receptor. Con el fin de obtener expresiones cerradas y exactas par los indicadores de rendimiento mencionados, se han desarrollo nuevos métodos o herramientas matemáticas que facilitan o, en algunos casos, hacen posible el análisis. En primer lugar, se han obtenido nuevas expresiones cerradas para las integrales del tipo Lipschitz-Hankel y para la distribución de los elementos de la diagonal de matrices Wishart complejas. Posteriormente, estos resultados han sido aplicados al análisis de prestaciones de distintos sistemas MIMO en condiciones no-ideales. Concretamente, se han obtenido nuevas expresiones cerrradas de la probabilidad de outage para: sistemas MRC con interferencia co-canal, sistemas MIMO con correlación espacial entre antenas, y sistemas MIMO MRC con un canal de retorno limitado en velocidad. Además, se han obtenido expresiones cerradas para la probabilidad de error en sistemas de diversidad en recepción que emplean modulaciones no coherentes y no ortogonales

Cooperative Transmission Techniques in Wireless Communication Networks

Cooperative communication networks have received significant interests from both academia and industry in the past decade due to its ability to provide spatial diversity without the need of implementing multiple transmit and/or receive antennas at the end-user terminals. These new communication networks have inspired novel ideas and approaches to find out what and how performance improvement can be provided with cooperative communications. The objective of this thesis is to design and analyze various cooperative transmission techniques under the two common relaying signal processing methods, namely decode-and-forward (DF) and amplify-and-forward (AF). For the DF method, the thesis focuses on providing performance improvement by mitigating detection errors at the relay(s). In particular, the relaying action is implemented adaptively to reduce the phenomenon of error propagation: whether or not a relay’s decision to retransmit depends on its decision variable and a predefined threshold. First, under the scenario that unequal error protection is employed to transmit different information classes at the source, a relaying protocol in a singlerelay network is proposed and its error performance is evaluated. It is shown that by setting the optimal signal-to-noise ratio (SNR) thresholds at the relay for different information classes, the overall error performance can be significantly improved. Second, for multiple-relay networks, a relay selection protocol, also based on SNR thresholds, is proposed and the optimal thresholds are also provided. Third, an adaptive relaying protocol and a low-complexity receiver are proposed when binary frequency-shift-keying (FSK) modulation is employed and neither the receiver nor the transmitter knows the fading coefficients. It is demonstrated that large performance improvements are possible when the optimal thresholds are implemented at the relays and destination. Finally, under the scenario that there is information feedback from the destination to the relays, a novel protocol is developed to achieve the maximum transmission throughput over a multiple-relay network while the bit-error rate satisfies a given constraint. With the AF method, the thesis examines a fixed-gain multiple-relay network in which the channels are temporally-correlated Rayleigh flat fading. Developed is a general framework for maximum-ratio-combining detection when M-FSK modulation is used and no channel state information is available at the destination. In particular, an upper-bound expression on the system’s error performance is derived and used to verify that the system achieves the maximal diversity order. Simulation results demonstrate that the proposed scheme outperforms the existing schemes for the multiple-relay network under consideration

Unified Performance Analysis of Mixed Line of Sight RF-FSO Fixed Gain Dual-Hop Transmission Systems

In this work, we carry out a unified performance analysis of a dual-hop fixed gain relay system over asymmetric links composed of both radio-frequency (RF) and unified free-space optics (FSO) under the effect of pointing errors. The RF link is modeled by the Nakagami-$m$ fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e. heterodyne detection and intensity modulation with direct detection (IM/DD)). In particular, we derive new unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generation function, and the moments of the end-to-end signal-to-noise ratio of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability, the higher-order amount of fading, and the average bit-error rate of a variety of binary modulations in terms of the Meijer's G function. Further, an exact closed-form expression for the end-to-end ergodic capacity for the Nakagami-$m$-unified FSO relay links is derived in terms of the bivariate G function. All the given results are verified via Computer-based Monte-Carlo simulations

Forwarding strategies and optimal power allocation for coherent and noncoherent relay networks

In fading wireless channels, relays are used with the aim of achieving diversity and thus overall performance gain. In cooperative relay networks, various forwarding techniques like amplify and forward (AF) and decode and forward (DF) are used at the relay for better throughput and improved BER performance than traditional multihop systems. In a power constrained environment, the performance can be further improved by using an optimal power allocation strategy. The relative position of the relay with respect to the source and destination also has an immense effect on the efficacy of the relay.;We position the relay at various positions in a planar grid, with the position of source and destination being fixed, and we investigate the effect that the positioning of the relay has on a relaying system. We use our three terminal model to optimize the power allocation under total transmit power constraint, to maximize the instantaneous signal-to-noise ratio (SNR) at destination, and thus achieve improved throughput and BER performance, while using AF and DF protocols. We evaluate the performance of our system for both coherent and noncoherent modulation in a Rayleigh block fading channel. Quadrature phase shift keying (QPSK) is used in the coherent case and 4-Frequency shift keying (4-FSK) is used in the noncoherent case.;Previous works involving power allocation schemes have mainly concentrated on optimizing information theoretic quantities like capacity and outage probability. We derive expressions for instantaneous SNR using our model and optimize the power allocation based on that, with the final aim of achieving improved uncoded BER. Analytical expressions of the instantaneous SNR at the destination are derived for both AF and DF. These expressions are numerically optimized to obtain an optimum power allocation strategy for each position of the relay in both the AF and DF schemes using coherent or noncoherent detection.;We compare the performance of the AF and DF protocols based on their positional BER and throughput at different received SNR and notice that our power optimized schemes outperform existing power control schemes at certain areas. Finally we also identify the shape and area of the regions where relaying would provide performance gains for both the protocols at different received SNRs

Performance analysis of mixed Nakagami- m and Gamma–Gamma dual-hop FSO transmission systems

In this paper, we carry out a unified performance analysis of a dual-hop relay system over the asymmetric links composed of both radio-frequency (RF) and unified free-space optical (FSO) links under the effect of pointing errors. Both fixed and variable gain relay systems are studied. The RF link is modeled by the Nakagami-m fading channel and the FSO link by the Gamma-Gamma fading channel subject to both types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection). In particular, we derive new unified closed-form expressions for the cumulative distribution function, the probability density function, the moment generating function (MGF), and the moments of the end-to-end signal-to-noise ratio (SNR) of these systems in terms of the Meijer's G function. Based on these formulas, we offer exact closed-form expressions for the outage probability (OP), the higher order amount of fading, and the average bit error rate (BER) of a variety of binary modulations in terms of the Meijer's G function. Furthermore, an exact closed-form expression of the end-to-end ergodic capacity is derived in terms of the bivariate G function. Additionally, by using the asymptotic expansion of the Meijer's G function at the high-SNR regime, we derive new asymptotic results for the OP, the MGF, and the average BER in terms of simple elementary functions