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Communications, IET

Issue 10 • Date July 3 2014

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Displaying Results 1 - 22 of 22
  • Single-band full-duplex MAC protocol for distributed access networks

    Page(s): 1663 - 1673
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (638 KB)  

    Recent advances in wireless communications promised the realisation of a revolutionary technique, called full-duplex (FD), which allows communication in both directions at the same time and over the same channel. However, the viability of FD in the physical layer requires the support of the MAC layer to fully spread the advantages of this technology to the whole wireless network. In this study, the authors introduce a distributed MAC protocol, termed distributed-access FD MAC, suitable for multi-hop communications whereby nodes are FD enabled. Using this protocol, a data packet can be forwarded by a number of nodes along a multi-hop path with un-contented access to the channel at each hop except for the head node. After detailing the specifications of this protocol, they establish a finite-state discrete-time Markov model to evaluate its performance. Using probabilistic mathematical methods, they derive important quantitative metrics such as path delay and throughput. Numerical results are provided and demonstrate the considerable improvement in network performance that the proposed protocol achieves compared with CSMA/CA half-duplex access mechanism. View full abstract»

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  • Performance of Nth-best antenna selection diversity systems with co-channel interference and outdated channel information

    Page(s): 1674 - 1683
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (675 KB)  

    In this study, the authors evaluate the performance of space diversity systems with the Nth-best antenna selection scheme in the presence of interference and outdated channel information (OC1). The Nth-best antenna selection scheme is efficient in situations where the second or even the Nth best antenna is mistakenly selected by the destination instead of the first best antenna for data reception. In this study, they first derive the cumulative distribution function (CDF) of the end-to-end (e2e) signal-to-interference plus noise ratio at the selection scheme combiner output. This CDF is then used to derive exact closed-form expressions for the e2e outage probability and symbol error probability (SEP) of the system. In the analysis, the channels of the desired user and the interferers are assumed to follow Rayleigh distribution. Furthermore, to obtain more about system insights, the performance is studied at the high signal-to-noise ratio (SNR) regime where the diversity order and coding gain are derived. Monte Carlo simulations are provided to validate the derived analytical and asymptotic expressions. Main results illustrate that with an interference power that is not scaling with SNR, the system can still achieve diversity gain when more receive antennas are used. Also, findings show that the diversity order of the system is linearly decreasing with increasing the order of the antenna, and linearly increasing with decreasing it. Furthermore, results illustrate that as the higher the correlation coefficient between the SNRs of antennas at the selection and transmission time instances, the better the achieved performance. View full abstract»

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  • Simply decoded efficient full-rate space-time block codes over correlated Rician fading channels

    Page(s): 1684 - 1695
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (997 KB)  

    A novel technique is presented to design efficient full-rate space-time block codes (STBCs) over correlated Rician fading channels. The authors first derive a formula for the achievable information rate of a linear dispersion coded multi-input single-output system as a function of correlation at the transmitter in a Rician fading channel. In addition, the authors obtain the bit-error-rate (BER) equations for this system, when multiple phase shift keying and multiple quadrature amplitude modulation schemes are used at the transmitter. Therefore with regard to derived formulae and using a genetic algorithm, a method is presented to construct STBCs over correlated Rician fading channels. The efficient designed STBCs for two and four transmit antennas enjoy full-rate, simple structure, simple processing at the receiver, better BER performance than associated orthogonal STBCs at practical signal-to-noise ratios (SNRs) and higher achievable information rate than them at all SNRs. View full abstract»

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  • Best binary equivocation code construction for syndrome coding

    Page(s): 1696 - 1704
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (254 KB)  

    Traditionally, codes are designed for an error correcting system to combat noisy transmission channels and achieve reliable communication. These codes can be used in syndrome coding, but it is shown in this study that the best performance is achieved with codes specifically designed for syndrome coding. In the view of the security of the communication, the best codes are the codes, which have the highest value of an information secrecy metric, the equivocation rate, for a given code length and code rate and are well packed codes. A code design technique is described, which produces the best binary linear codes for the syndrome coding scheme. An efficient recursive method to determine the equivocation rate for the binary symmetric channel and any linear binary code is also presented. A large online database of best equivocation codes for the syndrome coding scheme has been produced using the code design technique with some examples presented in the study. The presented results show that the best equivocation codes produce a higher level of secrecy for the syndrome coding scheme than almost all best known error correcting codes. Interestingly, it is unveiled that some outstanding best known error correcting codes are also best equivocation codes. View full abstract»

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  • Precoder designs for jointly suppressing out-of-band emission and peak-to-average power ratio in an orthogonal frequency division multiplexing system

    Page(s): 1705 - 1713
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (650 KB)  

    High peak-to-average-ratio (PAPR) and large out-of-band emission (OOBE) are the two main shortcomings of orthogonal frequency division multiplexing (OFDM) signals for cognitive radios. Among all the existing techniques, it has been shown that precoding is an effective way for either reducing the PAPR or suppressing the OOBE. However, no work has focused on designing an effective precoding approach to reduce the PAPR and suppress the OOBE simultaneously. In this study, three new precoding approaches that can jointly suppress OOBE and reduce PAPR simultaneously are presented. The simulation results show that, firstly, all the three proposed precoding approaches can achieve the same power spectral density performance as the typical OOBE-suppression precoding approach with the same spectral efficiency. Secondly, their PAPR performances are only slightly worse than the typical PAPR-reduction precoding approach with a similar computational complexity. Finally, two of the three proposed precoding approaches do not cause any bit error rate (BER) performance degradation with respect to the conventional OFDM system. The abilities to suppress OOBE and PAPR jointly and to maintain the good BER performance make two of the three proposed approaches very favourable for practical applications. View full abstract»

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  • Alien crosstalk elimination in digital subscriber line systems

    Page(s): 1714 - 1723
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (825 KB)  

    Elimination of alien crosstalk in coordinated digital subscriber line systems is investigated in this study. In the upstream, the process of crosstalk elimination may take advantage of available coordination at the receiver side. As the signal received at the coordinated terminals can be corrupted by alien crosstalk, the reception process involves passing the signals received at the coordinated terminals through a spatial whitening operation. As part of the contribution in this study, a method is proposed to obtain the spatial whitening filter coefficients. These coefficients are estimated from the cyclic spectrum of alien crosstalk received at the coordinated system terminals, where transmission at the coordinated system is controlled to allow separating the cyclic spectra of both coordinated system and alien crosstalk signals. This study includes evaluation of the whitening receiver performance taking into account the effects of estimation errors. Theoretical derivations are illustrated by numerical results obtained for VDSL2 application. View full abstract»

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  • Saturated distributed coordination function Markov model for noisy soft-real-time industrial wireless networks

    Page(s): 1724 - 1735
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1330 KB)  

    The use of wireless technology in industrial networks is becoming more popular due to its numerous advantages. Providing an accurate model to study its performance parameters, is an essential step in designing a reliable and real-time industrial wireless network protocol. Most of the existing models are accurate only for data networks which have large packet payloads and high signal to noise ratio (SNR) characteristics, and cannot be applied to study the performance of industrial networks which have short packet lengths and are used in harsh and noisy environments. In this paper a novel three-dimensional discrete-time Markov chain (DTMC) model has been proposed for the IEEE 802.11-based industrial wireless networks using the distributed coordination function (DCF) as the medium access control (MAC) mechanism. It considers both causes of the backoff freezing: busy channel and the successive inter-frame space (IFS) waiting phase. In this way, it provides a much more accurate estimation of the channel access and collision probabilities, resulting in more accurate network metric calculations. Also, based on the proposed model, a simple and accurate packet delay analysis is provided in the worst-case saturated traffic and error-prone channel condition which in comparison with similar works provides more accurate results. View full abstract»

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  • Adaptive multi-task compressive sensing for localisation in wireless local area networks

    Page(s): 1736 - 1744
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (689 KB)  

    The spatially distributed sparsity of the mobile devices (MDs) in indoor wireless local area networks (WLANs) makes compressive sensing (CS) based localisation algorithms feasible and desirable. In this Letter, the authors exploit the most recent developments in CS to efficiently perform localisation in WLANs and design an accurate indoor localisation scheme by taking advantage of the theory of multi-task Bayesian CS (MBCS). The proposed scheme assembles the strength measurements of signals from the MDs to distinct access points (APs) and jointly utilises them at a central unit or a specific AP to achieve localisation, thus being able to alleviate the burden of MDs while simultaneously giving a precise estimation of the locations. Afterwards, they give a deeper insight into the localisation problem in more practical scenarios with varying number of MDs and investigate two different adaptive algorithms to meet the satisfactory localisation error requirement. Compared with the conventional MBCS algorithms, simulation results validate that both adaptive algorithms could provide superior localisation accuracy and exhibit stronger resilience to the changes in the number of MDs. View full abstract»

    Open Access
  • Signal detection assisted from channel weight prediction for delay-sensitive orthogonal frequency-division multiplexing communications

    Page(s): 1745 - 1750
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (278 KB)  

    In signal coherent detection, data-aided (DA) method has high detection accuracy, but unavoidably suffers from a large processing delay. Meanwhile, a decision-directed (DD) method incurs no processing delay, but suffers from error propagation problem. Motivated by the above problems of DA and DD methods, the authors present a novel signal detection algorithm for delay-sensitive applications employing orthogonal frequency-division multiplexing systems. The proposed detection method provides similar detection accuracy to the DA method and incurs no processing delay. This method employs channel estimation followed by linear prediction and interpolation to obtain the channel-state information for symbol detection. To achieve a better prediction performance, they perform the linear prediction on the channel taps in the time domain, and conduct the interpolation using a raised cosine filter. Simulations on physical channel models verify the improvements of the proposed method. View full abstract»

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  • Performance analysis of interference-limited cooperative systems with relay selection over independent log-normal fading channels

    Page(s): 1751 - 1761
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    Closed-form expressions of the upper and lower bounds of the outage probability are derived for interference-limited dual-hop decode-and-forward and channel-state-information-assisted amplify-and-forward relay systems using three relay selection (RS) schemes [optimal source-relay link (OSRL) scheme, optimal relay-destination link (ORDL) scheme and optimal source-relay-destination link (OSRDL) scheme] over independent log-normal fading channels. Multiple interferers at both relay and destination are considered. The diversity order of the targeted cooperative system under the three different RS schemes is analysed. The analysis shows that the asymptotic relative diversity orders (ARDO) for OSRL, ORDL and OSRDL schemes are 2, 2 and (N + 1) (where N is the number of the relay candidates), respectively. Finally, the ARDO is verified by simulation results. View full abstract»

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  • Effects of atmospheric turbulence and misalignment fading on performance of serial-relaying M-ary pulse-position modulation free-space optical systems with partially coherent Gaussian beam

    Page(s): 1762 - 1768
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (543 KB)  

    A novel method is presented to analyse the effects of atmospheric turbulence and misalignment fading (or pointing error) on performance of serial-relaying M-ary pulse-position modulation (PPM) free-space optical (FSO) systems. This study is more comprehensive than previous ones, since the effect of beam size variation due to turbulence by using the partially coherent Gaussian beam model is taken into account. In addition, a closed-form expression is formulated for bit error rate of serial-relaying M-ary PPM FSO systems over Gamma-Gamma atmospheric turbulence channel, taking into account the effects of atmospheric attenuation, extinction ratio and signal-dependent noise. The authors find that the laser source's coherent parameter, which governs the beam size at the receiver, plays an important role in the system design. If this parameter is not chosen properly, the system impairment will be either dominated by pointing error or geometric spreading loss. Thanks to the use of serial-relaying and M-ary PPM, the effects of atmospheric turbulence and misalignment fading is mitigated; hence the ability of combating atmospheric turbulence and the transmission distance of FSO systems are significantly improved. In addition, useful information for system design, such as the required number of relays for a specific turbulence strength and transmission distance, could be obtained from the numerical results. View full abstract»

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  • Interference alignment in cognitive radio networks

    Page(s): 1769 - 1777
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    A fast algorithm to perform interference alignment (IA) in a cognitive radio network is proposed. Here, the authors consider a network consisting of multiple primary users (PUs) and secondary users (SUs). Although the PUs are cooperating through IA and their rates are maximised by water-filling algorithm, in the secondary network, the authors try to choose the precoding matrices of the SUs such that the interferences at the primary receivers are aligned away from the desired subspaces of the primary receivers. Besides, the interference cancellation of the PUs on the secondary links is considered through designing the post-processing matrices for the secondary links. In this way, their mutual harmful effects are suppressed and SUs could transmit their information simultaneously on the same frequency or time without causing/receiving any interference to/from the primary links. Meanwhile, the feasibility condition for the secondary network regarding the mentioned constraints is investigated. In addition, the rates of the secondary links are maximised by water-filling algorithm. The proposed iterative algorithm is an improved version of minimum weighted leakage interference algorithm with a much faster convergence rate. The analytical results are confirmed through simulations. View full abstract»

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  • Outage probability analysis of space-time block coding-orthogonal frequency division multiplexing cooperative systems

    Page(s): 1778 - 1787
    Save to Project icon | PDF file iconPDF (378 KB)  
    Freely Available from IEEE
  • Performance analysis of relay-multiplexing scheme in cellular systems employing massive multiple-input multiple-output antennas

    Page(s): 1788 - 1799
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (882 KB)  

    This study presents the symbol error probability (SEP) analysis of relay-multiplexing scheme in relay-assisted cellular systems such as the IEEE 802.16j and upcoming fifth generation (5G) systems. The availability of multiple relay paths in these systems motivates two relay configurations: (i) relay diversity and (ii) relay multiplexing. Available works in the literature have focused on the relay diversity methods. In this study, we explore the relay-multiplexing alternative whereby relay stations (RSs) act as independent data pipes for transmitting multiple independent data streams from the base station (BS) to the mobile station (MS). We examine the case when the BS is equipped with massive multiple-input multiple-output (MIMO) antennas, transmitting independent data streams to several MS simultaneously via different relay paths. We derive analytical expressions for the SEP performance of the proposed scheme, and also complement the analysis with simulations. The results show that parallel relaying of independent data streams via different RSs has acceptable SEP performance while boosting the capacity of the system linearly with the number of parallel RSs available in the system. The results also show that when this relaying approach is combined with the emerging massive MIMO techniques, a tremendous boost in data rate can be achieved. View full abstract»

    Open Access
  • Ultra-wideband-based multilateration technique for indoor localisation

    Page(s): 1800 - 1809
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (863 KB)  

    In this study, the authors present a novel geometrically driven multilateration technique that is based on ultra-wideband (UWB) technology. The authors refer to their proposed solution as time reflection of arrival (TROA). They demonstrate in this study how the position estimation error is improved upon by carefully considering the inherent properties of the UWB technology and the reflection properties of transmitted UWB signals. By a direct comparison between TROA and two widely used multilateration techniques, the authors show that indoor position estimation can be done much more effectively using their proposed solution. They also derive a new Cramér-Rao lower bound for TROA multilateration and use it to show its level of efficiency. View full abstract»

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  • Joint detection-decoding of majority-logic decodable non-binary low-density parity-check coded modulation systems: an iterative noise reduction algorithm

    Page(s): 1810 - 1819
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (930 KB)  

    In this study, the authors present a low-complexity iterative joint detection-decoding algorithm for majority-logic decodable non-binary low-density parity-check (LDPC) coded modulation systems. In the proposed algorithm, a hard-in-hard-out decoder is combined with a hard-decision signal detector in an iterative manner. Each iteration consists of five phases. Firstly, the detector makes hard decisions based on the iteratively updated `received' signals; secondly, these hard decisions are distributed via variable nodes to check nodes; thirdly, check nodes compute hard extrinsic messages; fourthly, each variable node counts hard extrinsic messages from its adjacent check nodes and feeds back to the detection node the symbol with the most votes as well as the difference between the most votes and the second most votes; finally, these feedbacks are used to shift each `received' signal point along an estimated direction to possibly reduce noise. The proposed algorithm requires only integer operations and finite field operations and consequently can be implemented with simple combinational logic circuits in practical systems. Simulation results show that the proposed algorithm performs well and hence serves as an attractive candidate for trading off performance against complexity for majority-logic decodable non-binary LDPC codes. View full abstract»

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  • Low complexity user scheduling for multi-antenna Gaussian broadcast systems with quality of service requirements

    Page(s): 1820 - 1830
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1089 KB)  

    In this study, the authors propose a low complexity user scheduling for multi-antenna broadcast systems with a large number of users with diverse delay-quality of service (QoS) assurances. Owing to the exclusive user scheduling constraints, the optimisation is combinatorial. Furthermore, by adopting effective capacity and effective bandwidth to illustrate the behaviours of different traffic characteristics such as different source statistics and queue dynamics, the delay-bound violation probability constraints can be converted into equivalent minimum data rate constraints. To reduce the computational complexity, they use genetic algorithm (GA) to perform scheduling, instead of a brute-force exhaustive search (ES) over all possible user subsets. By comparing the complexity of GA and ES, they show that GA is a rapid, although suboptimal, option of performing user scheduling optimisation. Simulation results show that the proposed algorithm can not only maximise the achievable user sum data rate, but also keep the delay-bound violation probability of each user below a given threshold. View full abstract»

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  • Joint power control and component carrier assignment scheme in heterogeneous network with carrier aggregation

    Page(s): 1831 - 1836
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (363 KB)  

    A distributed interference coordination scheme is proposed to alleviate cross-tier and inner-tier interference in heterogeneous network (HetNet), consisting of a power control strategy based on game theory to acquire both Nash equilibrium among femtocells and Stackelberg equilibrium between femtocells and macrocells. Component carrier assignment is the other interference coordination dimension for HetNet with carrier aggregation. The proposed method is a two-dimensional interference coordination scheme combining power control and component carrier assignment. The simulation results demonstrate the effectiveness and improvement of the proposed scheme. View full abstract»

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  • Quasi-cyclic low-density parity-check codes based on finite set systems

    Page(s): 1837 - 1849
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (683 KB)  

    A finite set system (FSS) is a pair (V, ℬ) where V is a finite set whose members are called points, equipped with a finite collection of its subsets ℬ whose members are called blocks. In this paper, FSSs are used to define a class of quasi-cyclic low-density parity-check (LDPC) codes, called FSS codes, such that the constructed codes possess large girth and arbitrary column-weight distributions. Especially, the constructed column weight-2 FSS codes have higher rates than the column weight-2 geometric and cylinder-type codes with the same girths. To find the maximum girth of FSS codes based on (V, ℬ), inevitable walks are defined in ℬ such that the maximum girth is determined by the smallest length of the inevitable walks in ℬ. Simulation results show that the constructed FSS codes have very good performance over the additive white Gaussian noise channel with iterative decoding and achieve significantly large coding gains compared with the random-like LDPC codes of the same lengths and rates. View full abstract»

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  • Performance analysis comparison of transmit antenna selection with maximal ratio combining and orthogonal space time block codes in equicorrelated Rayleigh fading multiple input multiple output channels

    Page(s): 1850 - 1858
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (447 KB)  

    In this study, bit error rate (BER) performance of multiple input multiple output (MIMO) systems employing transmit antenna selection with maximal ratio combining (TAS/MRC) and orthogonal space time block codes (OSTBC) is analysed and compared. Analysis has been done for several modulation schemes in equicorrelated Rayleigh fading channels. Novel infinite series expressions for BER of TAS/MRC are proposed in this work. The authors observe that the existing literature on performance analysis of TAS/MRC in correlated channels implicitly or explicitly assume no correlation on the transmitter side. In this work the authors overcome this shortcoming. An alternate closed-form expression for BER performance of OSTBC MIMO systems is derived. This closed-form expression is computationally efficient than existing expressions. Monte Carlo simulations were performed to validate the analytical results. It has been observed that TAS/MRC outperforms OSTBC in terms of BER performance in equicorrelated Rayleigh fading channel. As a case study, performance comparison of cognitive radio (CR) links employing OSTBC and TAS/MRC MIMO systems is investigated in order to show the usefulness of the present analytical study. Even though TAS is the optimum transmit antenna technique in terms of BER performance, OSTBC seems to be a promising alternative for more realistic scenarios in CR systems. View full abstract»

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  • Minimax robust jamming techniques based on signal-to-interference-plus-noise ratio and mutual information criteria

    Page(s): 1859 - 1867
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    Jamming in defence applications is increasingly difficult because of advanced signal processing countermeasures. In this study, task-dependent power-constraint optimal jamming techniques are investigated. To prevent the target from being detected, a novel jamming technique is proposed to minimise the signal-to-interference-plus-noise ratio (SINR) of the radar for extended known and stochastic target. To impair the parameter estimation performance, another jamming technique is proposed which minimises the mutual information (MI) between the radar return and the stochastic target impulse response. The optimal jamming spectrum is obtained assuming that the jammer has intercepted the radar waveform generally. However, the precise characteristic of radar waveform is impossible to capture in practice. To model this, it is considered that the waveform spectrum lies in an uncertainty class confined by known upper and lower bounds. Then, the minimax robust jamming is designed based on the SINR and MI criteria, which optimises the worst-case performance. Results demonstrate that the two criteria lead to different optimal jamming results but they have a close relationship from the Shannon's capacity equation which provides useful guidance on jamming power allocation for different jamming tasks. However, their behaviour with respect to the waveform uncertainty is the same. View full abstract»

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  • Investigation on power line communication in aircrafts

    Page(s): 1868 - 1874
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (434 KB)  

    Power line communication is envisaged for the future more electric aircraft and the scenario studied in this work deals with the cabin lighting system, since its tree-shaped architecture is sufficiently complicated to be representative of many other aircraft harness configurations. The statistical characteristics of the propagation channels are deduced from the measurements made on a representative test bench, the experimental values of the insertion gain being also compared with those obtained from a theoretical model based on the multiconductor transmission line theory. Field-programmable gate array-based modems have been designed and the performance of links are described and compared with predicted values deduced from a software tool simulating the link. View full abstract»

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