Showing papers on "Bit error rate published in 2012"
TL;DR: A VLC system based on a white LED for indoor broadband wireless access has been demonstrated, with twice the highest capacity that had been previously obtained by using an optimized discrete multitone modulation technique and adaptive bit- and power-loading algorithms.
Abstract: Light-emitting diodes (LEDs), which will be increasingly used in lighting technology, will also allow for distribution of broadband optical wireless signals. Visible-light communication (VLC) using white LEDs offers several advantages over the RF-based wireless systems, i.e., license-free spectrum, low power consumption, and higher privacy. Mostly, optical wireless can provide much higher data rates. In this paper, we demonstrate a VLC system based on a white LED for indoor broadband wireless access. After investigating the nonlinear effects of the LED and the power amplifier, a data rate of 1 Gb/s has been achieved at the standard illuminance level, by using an optimized discrete multitone modulation technique and adaptive bit- and power-loading algorithms. The bit-error ratio of the received data was $1.5\cdot 10^{-3}$ , which is within the limit of common forward error correction (FEC) coding. These results twice the highest capacity that had been previously obtained.
460 citations
TL;DR: Simulation results show that the developed resource allocation scheme outperforms the conventional scheme, particularly when the BER ratio of HQ packets to LQ packets is larger than one and an empirical allocation scheme is proposed to allocate better chunks to HQ packets.
Abstract: In high speed train (HST) system, real-time multimedia entertainments are very important applications in which a data stream often contains packets with different quality of service requirements For example, video stream encoded with scalability contains the base layer packets with high quality (HQ) bit error rate (BER) requirement and enhancement layers' packets with low quality (LQ) BER requirement When a conventional allocation approach, which only considers one BER constraint for one data stream, is applied to orthogonal frequency division multiple access (OFDMA) systems, the BER constraint will be the strictest one among multiple requirements from different types of packets, which leads to inefficient allocation when each data stream has multiple BER requirements This paper aims to develop novel resource allocation approach by considering multiple BER requirements for different types of packets in one data stream In order to not only simplify the resource allocation, but also to compensate for the channel estimation error caused by Doppler shift in the HST environment, a proper number of contiguous subcarriers are grouped into chunks and spectrum is allocated chunk by chunk Simulation results show that the developed resource allocation scheme outperforms the conventional scheme, particularly when the BER ratio of HQ packets to LQ packets is larger than one Furthermore, in order to reduce the complexity of resource allocation further, an empirical allocation scheme is proposed to allocate better chunks to HQ packets It is shown that the performance of the empirical allocation scheme is quite close to that of the optimal scheme
213 citations
TL;DR: Error Resilient System Architecture (ERSA) is presented, a low-cost robust system architecture for emerging killer probabilistic applications such as Recognition, Mining and Synthesis (RMS) applications and may be adapted for general-purpose applications that are less resilient to errors.
Abstract: There is a growing concern about the increasing vulnerability of future computing systems to errors in the underlying hardware. Traditional redundancy techniques are expensive for designing energy-efficient systems that are resilient to high error rates. We present Error Resilient System Architecture (ERSA), a robust system architecture which targets emerging killer applications such as recognition, mining, and synthesis (RMS) with inherent error resilience, and ensures high degrees of resilience at low cost. Using the concept of configurable reliability, ERSA may also be adapted for general-purpose applications that are less resilient to errors (but at higher costs). While resilience of RMS applications to errors in low-order bits of data is well-known, execution of such applications on error-prone hardware significantly degrades output quality (due to high-order bit errors and crashes). ERSA achieves high error resilience to high-order bit errors and control flow errors (in addition to low-order bit errors) using a judicious combination of the following key ideas: 1) asymmetric reliability in many-core architectures; 2) error-resilient algorithms at the core of probabilistic applications; and 3) intelligent software optimizations. Error injection experiments on a multicore ERSA hardware prototype demonstrate that, even at very high error rates of 20 errors/flip-flop/108 cycles (equivalent to 25000 errors/core/s), ERSA maintains 90% or better accuracy of output results, together with minimal impact on execution time, for probabilistic applications such as K-Means clustering, LDPC decoding, and Bayesian network inference. In addition, we demonstrate the effectiveness of ERSA in tolerating high rates of static memory errors that are characteristic of emerging challenges related to SRAM Vccmin problems and erratic bit errors.
199 citations
TL;DR: Magnetic induction (MI) is a promising technique for UWCNs that is not affected by large propagation delays, multipath propagation, and fading and the results prove the feasibility of MI communication in underwater environments.
Abstract: Although acoustic waves are the most versatile and widely used physical layer technology for underwater wireless communication networks (UWCNs), they are adversely affected by ambient noise, multipath propagation, and fading. The large propagation delays, low bandwidth, and high bit error rates of the underwater acoustic channel hinder communication as well. These operational limits call for complementary technologies or communication alternatives when the acoustic channel is severely degraded. Magnetic induction (MI) is a promising technique for UWCNs that is not affected by large propagation delays, multipath propagation, and fading. In this paper, the MI communication channel has been modeled. Its propagation characteristics have been compared to the electromagnetic and acoustic communication systems through theoretical analysis and numerical evaluations. The results prove the feasibility of MI communication in underwater environments. The MI waveguide technique is developed to reduce path loss. The communication range between source and destination is considerably extended to hundreds of meters in fresh water due to its superior bit error rate performance.
191 citations
TL;DR: A systematic method for characterizing semiconductor-laser phase noise, using a low-speed offline digital coherent receiver, and can predict the bit-error rate (BER) performance of multi-level modulated optical signals at 10 Gsymbol/s.
Abstract: We develop a systematic method for characterizing semiconductor-laser phase noise, using a low-speed offline digital coherent receiver. The field spectrum, the FM-noise spectrum, and the phase-error variance measured with such a receiver can completely describe phase-noise characteristics of lasers under test. The sampling rate of the digital coherent receiver should be much higher than the phase-fluctuation speed. However, 1 GS/s is large enough for most of the single-mode semiconductor lasers. In addition to such phase-noise characterization, interpolating the taken data at 1.25 GS/s to form a data stream at 10 GS/s, we can predict the bit-error rate (BER) performance of multi-level modulated optical signals at 10 Gsymbol/s. The BER degradation due to the phase noise is well explained by the result of the phase-noise measurements.
176 citations
TL;DR: A set of joint transmit diversity selection and relay selection algorithms based on discrete iterative stochastic optimization for the uplink of cooperative multiple-input-multiple-output (MIMO) systems are proposed and shown to outperform conventional cooperative transmission and match that of the optimal exhaustive solution.
Abstract: In this paper, we propose a set of joint transmit diversity selection (TDS) and relay selection (RS) algorithms based on discrete iterative stochastic optimization for the uplink of cooperative multiple-input-multiple-output (MIMO) systems. Decode-and-forward (DF) and amplify-and-forward (AF) multirelay systems with linear minimum mean square error (MSE), successive interference cancelation, and adaptive reception are considered. The problems of TDS and RS are expressed as MSE and mutual information (MI) joint discrete optimization problems and solved using iterative discrete stochastic algorithms. Such an approach circumvents the need for exhaustive searching and results in a range of procedures with low complexity and increased speed of convergence that can track the optimal selection over an estimated channel. The proposed schemes are analyzed in terms of their complexity, convergence, and diversity benefits and are shown to be both stable and computationally efficient. Their performance is then evaluated via MSE, MI, and bit error rate comparisons and shown to outperform conventional cooperative transmission and, in the majority of scenarios, match that of the optimal exhaustive solution.
163 citations
TL;DR: It is shown via computer simulations that the derived upper bound becomes very tight with increasing signal-to-noise ratio (SNR) and the SM scheme is quite robust to channel estimation errors.
Abstract: This work investigates the negative effects of channel estimation errors on the performance of spatial modulation (SM) when operating over flat Rayleigh fading channels. The pairwise error probability of the SM scheme is derived in the presence of channel estimation errors and an upper bound on the average bit error probability is evaluated for M-PSK and M-QAM signalling. It is shown via computer simulations that the derived upper bound becomes very tight with increasing signal-to-noise ratio (SNR) and the SM scheme is quite robust to channel estimation errors.
163 citations
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TL;DR: An approximate maximum-likelihood decoder is developed, called the bubble decoder, which runs in time polynomial in the message size and achieves the Shannon capacity over both additive white Gaussian noise (AWGN) and binary symmetric channel (BSC) models.
Abstract: Spinal codes are a new class of rateless codes that enable wireless networks to cope with time-varying channel conditions in a natural way, without requiring any explicit bit rate selection. The key idea in the code is the sequential application of a pseudo-random hash function to the message bits to produce a sequence of coded symbols for transmission. This encoding ensures that two input messages that differ in even one bit lead to very different coded sequences after the point at which they differ, providing good resilience to noise and bit errors. To decode spinal codes, this paper develops an approximate maximum-likelihood decoder, called the bubble decoder, which runs in time polynomial in the message size and achieves the Shannon capacity over both additive white Gaussian noise (AWGN) and binary symmetric channel (BSC) models. Experimental results obtained from a software implementation of a linear-time decoder show that spinal codes achieve higher throughput than fixed-rate LDPC codes, rateless Raptor codes, and the layered rateless coding approach of Strider, across a range of channel conditions and message sizes. An early hardware prototype that can decode at 10 Mbits/s in FPGA demonstrates that spinal codes are a practical construction.
159 citations
TL;DR: This paper develops the first optimal receiver design for diffusion-based molecular communication scenarios with and without inter-symbol interference, based on a linear and time invariant signal propagation model and an additive noise model based on Brownian motion molecular statistics.
155 citations
TL;DR: Highly power efficient and fully connected underwater communication networks (UWCNs) composed of transceiver and relay induction coils are presented and MI wireless communication is a promising alternative for UWCNs.
Abstract: Underwater physical medium is a challenging environment for communication using radio frequency (RF) or acoustic waves due to strong attenuation, delay, multi-path fading, power and cost limitations. Discovered a century ago, magneto-inductive (MI) communication technique stands as a strong alternative paradigm due to its independence of environmental impairments including multi-path fading, dynamic channels and high propagation delays experienced by acoustic waves. Furthermore, MI technique yields networking solutions exploiting low-cost, easily-deployable and flexible antenna structures, and the possibility of forming networks of magnetic waveguides defeating path loss. In this work, highly power efficient and fully connected underwater communication networks (UWCNs) composed of transceiver and relay induction coils are presented. Three dimensional (3D) UWCNs are analysed in terms of basic communication metrics, i.e, signal-to-noise ratio, bit-error rate, connectivity and communication bandwidth. The performance studies of realistic 3D networks covering hundreds of meters sea depths and a few km2 areas show that fully connected multi-coil networks with communication bandwidths extending from a few to tens of KHz are possible. Furthermore, the performance dependence on coil properties and network size is theoretically modelled. Results show that MI wireless communication is a promising alternative for UWCNs and future research challenges are pointed out.
136 citations
31 Dec 2012
TL;DR: A linear system description is obtained for the transmitter by ordering data in a time-frequency block structure and representing the processing steps upconversion, pulse shaping and upsampling as matrix operations.
Abstract: Generalized frequency division multiplexing is a non-orthogonal, digital multicarrier transmission scheme with attractive features that address the requirements of emerging applications of wireless communications systems in areas like cognitive radio and machine-to-machine communication. In this paper, first a linear system description is obtained for the transmitter by ordering data in a time-frequency block structure and representing the processing steps upconversion, pulse shaping and upsampling as matrix operations. Based on the transmitter, three standard ways of detecting the signal are derived and compared in terms of bit error performance in AWGN and Rayleigh multipath fading channels.
TL;DR: While Eve's channel has a quality equal to or better than that of Bob's channel, it is shown that the use of a hybrid automatic repeat-request protocol with authentication still allows achieving a sufficient level of security.
Abstract: This paper examines the use of nonsystematic channel codes to obtain secure transmissions over the additive white Gaussian noise wire-tap channel. Unlike the previous approaches, we propose to implement nonsystematic coded transmission by scrambling the information bits, and characterize the bit error rate of scrambled transmissions through theoretical arguments and numerical simulations. We have focused on some examples of Bose-Chaudhuri-Hocquenghem and low-density parity-check codes to estimate the security gap, which we have used as a measure of physical layer security, in addition to the bit error rate. Based on a number of numerical examples, we found that such a transmission technique can outperform alternative solutions. In fact, when an eavesdropper (Eve) has a worse channel than the authorized user (Bob), the security gap required to reach a given level of security is very small. The amount of degradation of Eve's channel with respect to Bob's that is needed to achieve sufficient security can be further reduced by implementing scrambling and descrambling operations on blocks of frames, rather than on single frames. While Eve's channel has a quality equal to or better than that of Bob's channel, we have shown that the use of a hybrid automatic repeat-request protocol with authentication still allows achieving a sufficient level of security. Finally, the secrecy performance of some practical schemes has also been measured in terms of the equivocation rate about the message at the eavesdropper and compared with that of ideal codes.
31 Dec 2012
TL;DR: This paper will explain how self-interference can be reduced by a basic and a double-sided serial interference cancellation technique and show that these interference cancellation techniques improve the GFDM bit error rate to match the theoretical performance of the well studied orthogonal frequency division multiplexing (OFDM).
Abstract: Generalized frequency division multiplexing (GFDM) is a new digital multicarrier concept. The GFDM modulation technique is extremely attractive for applications in a fragmented spectrum, as it provides the flexibility to choose a pulse shape and thus allows reduction of the out-of-band leakage of opportunistic cognitive radio signals into incumbent frequency space. However, this degree of freedom is obtained at the cost of loss of subcarrier orthogonality, which leads to self-inter-carrier-interference. This paper will explain how self-interference can be reduced by a basic and a double-sided serial interference cancellation technique and show that these interference cancellation techniques improve the GFDM bit error rate to match the theoretical performance of the well studied orthogonal frequency division multiplexing (OFDM).
TL;DR: To mitigate the negative impact of imperfect CSI, it is shown that power allocation (PA), by minimizing either the outage probability or the BER, can suitably be cast as the geometric-programming problem.
Abstract: In this paper, the impact of channel-state information (CSI) estimation error on the performance of an amplify-and-forward two-way multiple relay network has been investigated. In contrast to the existing literature, which assumes perfect self-interference cancellation, we consider imperfect self-interference cancellation at both sources that exchange information through multiple relays, and maximal-ratio combining is then applied to improve the decision statistics under imperfect signal detection. We derive the effective signal-to-noise ratio (SNR) subject to noisy channel estimation, and based on this SNR, the system outage probability is given. In addition, we derive the closed-form expression of the average system bit error rate (BER) and the asymptotic expressions for both outage probability and BER. Furthermore, instead of employing all relays, we examine the impact of imperfect CSI on a single relay selection (RS) scheme. To mitigate the negative impact of imperfect CSI, we show that power allocation (PA), by minimizing either the outage probability or the BER, can suitably be cast as the geometric-programming problem. Numerical results validate the correctness of the derived expressions and show that the adaptive-PA scheme outperforms the equal-PA scheme under the aggregated effect of imperfect CSI.
TL;DR: A probabilistic router formation and motion-planning approach by integrating the previously proposed stochastic channel learning framework with robotic router optimization is proposed, which results in a different robotic configuration, with a considerably better performance, as compared with only considering disk models for communication and/or maximizing the Fielder eigenvalue.
Abstract: In this paper, we consider the problem of robotic router formation, where two nodes need to maintain their connectivity over a large area by using a number of mobile routers. We are interested in the robust operation of such networks in realistic communication environments that naturally experience path loss, shadowing, and multipath fading. We propose a probabilistic router formation and motion-planning approach by integrating our previously proposed stochastic channel learning framework with robotic router optimization. We furthermore consider power constraints of the network, including both communication and motion costs, and characterize the underlying tradeoffs. Instead of taking the common approach of formation optimization through maximization of the Fiedler eigenvalue, we take a different approach and use the end-to-end bit error rate (BER) as our performance metric. We show that the proposed framework results in a different robotic configuration, with a considerably better performance, as compared with only considering disk models for communication and/or maximizing the Fielder eigenvalue. Finally, we show the performance with a simple preliminary experiment, with an emphasis on the impact of localization errors. Along this line, we show interesting interplays between the localization quality and the channel correlation/learning quality.
TL;DR: Analysis of the decode-and-forward (DF) protocol in the free space optical (FSO) links following the Gamma-Gamma distribution and average bit error rate of the DF relaying is obtained.
Abstract: We analyze performance of the decode-and-forward (DF) protocol in the free space optical (FSO) links following the Gamma-Gamma distribution. The cumulative distribution function (cdf) and probability density function (pdf) of a random variable containing mixture of the Gamma-Gamma and Gaussian random variables is derived. By using the derived cdf and pdf, average bit error rate of the DF relaying is obtained.
TL;DR: This paper investigates the impact of using outdated channel estimates for relay selection and signal amplification on the performance of amplify-and-forward (AF) relays under partial relay selection (PRS) and opportunistic relay selection (-) and finds that up to an order of magnitude increase in the outage probability is caused.
Abstract: This paper investigates the impact of using outdated channel estimates for relay selection and signal amplification on the performance of amplify-and-forward (AF) relays under partial relay selection (PRS) and opportunistic relay selection (ORS). In practice, outdated channel state information (CSI) can occur due to feedback or scheduling delay. Both variable gain (VG) AF and fixed gain AF schemes are considered. Outage probability, the average bit error rate (BER) and simplified high signal-to-noise ratio approximations are derived. The effect of parameters such as the number of relays, the rank of chosen relay, and the correlation between the delayed and current channel state information are analyzed. Outdated CSI for computing relay gains in PRS causes about 2 dB loss. In ORS, a 3% reduction in correlation causes up to an order of magnitude increase in the outage probability.
TL;DR: The results show that with different duty cycles the required data rates are not higher than the original value and less LED lamp power is required to guarantee the communication quality, which makes the dimming control system that satisfies both communication and illumination requirements easy to be implemented and power-saving.
Abstract: We investigate the performance of visible light communication (VLC) system with a pulse width modulation (PWM) dimming control scheme. Under this scheme, the communication quality in terms of number of transmitted bits and bit error rate (BER) of less than 10(-3) should be guaranteed. However, for on-off-keying (OOK) signal, the required data rate becomes 10 times as high as the original data rate when the duty cycle of dimming control signal is 0.1. To make the dimming control scheme easy to be implemented in VLC system, we propose the variable M-QAM OFDM VLC system, where M is adjusted according to the brightness of LED light in terms of duty cycle. The results show that with different duty cycles the required data rates are not higher than the original value and less LED lamp power is required to guarantee the communication quality, which makes the dimming control system that satisfies both communication and illumination requirements easy to be implemented and power-saving.
TL;DR: A robust iterative channel estimator based on a 2-D subspace spanned by generalized discrete prolate spheroidal sequences is designed, which ensures that the iterative receiver is able to converge to the same bit error rate (BER) as a receiver with perfect channel knowledge.
Abstract: This paper deals with channel estimation for orthogonal frequency-division multiplexing (OFDM) in time-variant wireless propagation channels. We particularly consider the challenges of the IEEE 802.11p standard, which is the worldwide dominant system for vehicular communications. For historic reasons, 802.11p uses a pilot pattern that is identical to the pattern used in 802.11a, which was initially designed for the estimation of indoor channels with little or no time variations. Therefore, this pilot pattern violates the sampling theorem for channels with both large delay spread and large Doppler spread, as often occurs in vehicular communications. To remedy this problem, we design a robust iterative channel estimator based on a 2-D subspace spanned by generalized discrete prolate spheroidal sequences. Due to the tight subspace design, the iterative receiver is able to converge to the same bit error rate (BER) as a receiver with perfect channel knowledge. Furthermore, we propose a backward compatible modification of the 802.11p pilot pattern such that the number of iterations sufficient for convergence can be reduced by a factor of 2-3, strongly reducing implementation complexity.
TL;DR: The latest results for OTDM transmission systems in combination with digital coherent detection achieving record-high serial data rates in a single-wavelength channel and a BER below the FEC limit is found.
Abstract: We present latest results for OTDM transmission systems in combination with digital coherent detection achieving record-high serial data rates in a single-wavelength channel. We show serial data transmission of 5.1 Tb/s (640 GBd) over 80-km and 10.2 Tb/s (1.28 TBd) over 29-km dispersion managed fiber (DMF). For 5.1-Tb/s transmission over 80-km DMF, the BER of all 128 OTDM-tributaries (both polarizations) is found to be below the hard-decision FEC-threshold, corresponding to an error-free net data rate of 4.8 Tb/s. In a 10.2-Tb/s experiment, the BER of all 256 TDM-tributaries (both polarizations) is found to be below the FEC-threshold in the back-to-back configuration. This translates to an error-free net data rate of 9.5 Tb/s. After transmission over a 29-km DMF negligible pulse broadening and a BER below the FEC limit is found.
TL;DR: Improvements in the methods of beam delay, angle, and power adaptation coupled with an imaging receiver are employed to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility.
Abstract: In this paper, we propose a mobile optical wireless system that employs beam delay adaptation, and makes use of our previously introduced beam angle and power adaptation multi-beam spot diffusing configuration in conjunction with an imaging receiver. Our ultimate goal is to improve the bandwidth, reduce the effect of intersymbol-interference, and increase the signal-to-noise ratio (SNR) when the transmitter operates at a higher data rate under the impact of multipath dispersion, background noise, and mobility. A significant reduction in the delay spread can be achieved compared to a conventional diffuse system (CDS) when an imaging receiver replaces a nonimaging receiver at the room's corner, where the delay spread is reduced from 2.4 ns to about 0.35 ns. Our proposed system, beam delay, angle, and power adaptation in a line strip multibeam spot diffusing configuration (BDAPA- LSMS), offers a reduction in delay spread by a factor of more than 10 compared with only the beam angle and power adaptation LSMS. An increase in channel bandwidth from 36 MHz (CDS) to about 9.8 GHz can be achieved when our methods of beam delay, angle, and power adaptation coupled with an imaging receiver are employed. These improvements enhance our system and enable it to operate at a higher data rate of 10 Gb/s. At a bit rate of 30 Mb/s, our proposed BDAPA-LSMS achieves about 50 dB SNR gain over conventional diffuse systems that employ a nonimaging receiver (CDS). Moreover, our simulation results show that the proposed BDAPA-LSMS at a bit rate of 10 Gb/s achieves about 32.3 dB SNR at the worst communication path under the presence of background noise and mobility while achieving a bit error rate below 10-9.
TL;DR: This paper introduces an effective receiver for the LDS-OFDM scheme, and proposes a framework to analyze and design this iterative receiver using extrinsic information transfer (EXIT) charts, and shows how the turbo MUDD is tuned using EXIT charts analysis.
Abstract: Low density signature orthogonal frequency division multiplexing (LDS-OFDM) is an uplink multi-carrier multiple access scheme that uses low density signatures (LDS) for spreading the symbols in the frequency domain. In this paper, we introduce an effective receiver for the LDS-OFDM scheme. We propose a framework to analyze and design this iterative receiver using extrinsic information transfer (EXIT) charts. Furthermore, a turbo multi-user detector/decoder (MUDD) is proposed for the LDS-OFDM receiver. We show how the turbo MUDD is tuned using EXIT charts analysis. By tuning the turbo-style processing, the turbo MUDD can approach the performance of optimum MUDD with a smaller number of inner iterations. Using the suggested design guidelines in this paper, we show that the proposed structure brings about 2.3 dB performance improvement at a bit error rate (BER) equal to 10-5 over conventional LDS-OFDM while keeping the complexity affordable. Simulations for different scenarios also show that the LDS-OFDM outperforms similar well-known multiple access techniques such as multi-carrier code division multiple access (MC-CDMA) and group-orthogonal MC-CDMA.
01 Jan 2012
TL;DR: The concept of non-systematic coded UW-OFDM, where the redundancy is no longer allocated to dedicated subcarriers, but distributed over all sub carriers is introduced, and optimum complex valued code generator matrices matched to the best linear unbiased estimator (BLUE) and to the linear minimum mean square error (LMMSE) data estimator, respectively are derived.
Abstract: In this paper, we expand our recently introduced concept of unique word orthogonal frequency division multiplexing (UW-OFDM) In UW-OFDM the cyclic prefixes (CPs) are replaced by deterministic sequences, the so-called unique words (UWs) The UWs are generated by appropriately loading a set of redundant subcarriers By that a systematic complex number Reed-Solomon (RS) code construction is introduced in a quite natural way, because an RS code may be defined as the set of vectors, for which a block of successive zeros occurs in the other domain wrt a discrete Fourier transform (For a fixed block different to zero, ie, a UW, a coset code of an RS code is generated) A remaining problem in the original systematic coded UW-OFDM concept is the fact that the redundant subcarrier symbols disproportionately contribute to the mean OFDM symbol energy In this paper we introduce the concept of non-systematic coded UW-OFDM, where the redundancy is no longer allocated to dedicated subcarriers, but distributed over all subcarriers We derive optimum complex valued code generator matrices matched to the best linear unbiased estimator (BLUE) and to the linear minimum mean square error (LMMSE) data estimator, respectively With the help of simulations we highlight the advantageous spectral properties and the superior bit error ratio (BER) performance of non-systematic coded UW-OFDM compared to systematic coded UW-OFDM and to CP-OFDM in additive white Gaussian noise (AWGN ) as well as in frequency selective environments
TL;DR: An ultra-high bit-rate inter-satellite optical wireless communication (IsOWC) system is proposed, which uses coherent optical quadrature phase-shift keying (QPSK) modulation technique and the authors have proposed a novel QPSK modulation technique for the design of IsOWC system for achieving higher coverage distance and data rate.
Abstract: An ultra-high bit-rate inter-satellite optical wireless communication (IsOWC) system is proposed in thisstudy. The system is designed and simulated up to the bit-rate of 400 Gbps. The proposed system is a non-diffused link or line-of-sight setup, which uses coherent optical quadrature phase-shift keying (QPSK) modulation technique. The performance of the system is analysed in terms of Q -factor, bit-error rate, eye opening and so on. The coverage distance observed with an input power level of 30 dBm for a bit-rate of 400, 160 and 100 Gbps are 4767, 7542 and 9532 km, respectively. Finally, the maximum bit-rate that can be communicated, for inter-satellite link at different orbits such as low-Earth orbit, medium-Earth orbit and geostationary Earth orbit are presented. To the best of the authors knowledge for the first time they have proposed a novel QPSK modulation technique for the design of IsOWC system for achieving higher coverage distance and data rate, which was not been addressed in any current or earlier publications.
03 Apr 2012
TL;DR: This paper presents a 60 GHz direct-conversion front-end and baseband transceiver, including analog and digital circuitry for the PHY functions, and is capable of more than 7 Gb/s 16QAM wireless communication for every channel of the 60 GHz standards.
Abstract: This paper presents a 60GHz direct-conversion front-end and baseband transceiver, including analog and digital circuitry for the PHY functions. The 65nm CMOS front-end consumes 319mW and 223mW in transmitting and receiving mode, respectively, and is capable of more than 7Gb/s 16QAM wireless communication for every channel of the 60GHz standards [1–3]. The 40nm CMOS baseband incorporating LDPC consumes 196mW and 398mW for 16QAM in transmitting and receiving mode, respectively. The entire system, including both RF and BB, using a 6dBi antenna built in an organic package [4] can transmit 3.1Gb/s over 1.8m in QPSK and 6.3Gb/s over 0.05m in 16QAM.
TL;DR: The results show that the proposed new scheme accurately estimates the states and information symbols, and provides a lower bit error rate (BER) than existing secure communication schemes, and the more accurately the MGSA estimates the parameters, the more noise the filter reduces.
TL;DR: New analytical expressions for the channel capacity under different transmission schemes are derived in the form of infinite series for the special case of integer μ values and exact tractable formulas for the average bit error rate of various modulation schemes are deduced.
Abstract: In this paper, we analyze and evaluate the performance of digital communication systems that operate over a composite fading channel following the η-μ/gamma distribution. More specifically, new analytical expressions for the channel capacity under different transmission schemes are derived in the form of infinite series. For the special case of integer μ values, simplified closed-form expressions are also obtained. Moreover, we deduce exact tractable formulas for the average bit error rate (BER) of various modulation schemes. In the high-power regime, simplified capacity and BER expressions are provided, revealing the implications of the model parameters on system performance. The relationship of the presented results with previously reported results on generalized- K and K fading channels is also established. We note that the theoretical results presented herein are given in analytical form, which can efficiently be evaluated.
TL;DR: Two novel linewidth-tolerant, low-complexity feedforward carrier phase estimation algorithms are described for dual-polarization 16-ary quadrature-amplitude-modulation with coherent detection.
Abstract: Two novel linewidth-tolerant, low-complexity feedforward carrier phase estimation algorithms are described for dual-polarization 16-ary quadrature-amplitude-modulation with coherent detection. For both algorithms, the carrier phase is estimated in two stages. The first stage employs either a simplified quadrature-phase-shift-keying (QPSK) partitioning algorithm or the blind phase search (BPS) algorithm. The second stage employs a novel QPSK constellation transformation algorithm. The performance and linewidth tolerance of both algorithms are evaluated using experimental and simulation data, and the hardware complexity is assessed. For both proposed two-stage algorithms, the linewidth symbol duration product is 1.3 × 10-4 for a 1 dB penalty in optical signal-to-noise ratio at a bit error ratio of 10-3. This performance is comparable to a single-stage BPS algorithm with a large number of test phases, but with a reduction of the hardware complexity by factors of about 2.5-11.
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TL;DR: A polar code-based concatenated scheme to be used in Optical Transport Networks (OTNs) is proposed and it is shown that the proposed scheme outperforms the existing methods by closing the gap to the capacity while avoiding error floor, and maintaining a low complexity at the same time.
Abstract: This paper investigates properties of polar codes that can be potentially useful in real-world applications. We start with analyzing the performance of finite-length polar codes over the binary erasure channel (BEC), while assuming belief propagation as the decoding method. We provide a stopping set analysis for the factor graph of polar codes, where we find the size of the minimum stopping set. We also find the girth of the graph for polar codes. Our analysis along with bit error rate (BER) simulations demonstrate that finite-length polar codes show superior error floor performance compared to the conventional capacity-approaching coding techniques. In order to take advantage from this property while avoiding the shortcomings of polar codes, we consider the idea of combining polar codes with other coding schemes. We propose a polar code-based concatenated scheme to be used in Optical Transport Networks (OTNs) as a potential real-world application. Comparing against conventional concatenation techniques for OTNs, we show that the proposed scheme outperforms the existing methods by closing the gap to the capacity while avoiding error floor, and maintaining a low complexity at the same time.