Error Performance Analysis Research Articles

New Trellis Code Design for Spatial Modulation

Spatial modulation (SM), in which multiple antennas are used to convey information besides the conventional M-ary signal constellations, is a new multiple-input multiple-output (MIMO) transmission technique, which has recently been proposed as an alternative to V-BLAST (vertical Bell Labs layered space-time). In this paper, a novel MIMO transmission scheme, called spatial modulation with trellis coding (SM-TC), is proposed. Similar to the conventional trellis coded modulation (TCM), in this scheme, a trellis encoder and an SM mapper are jointly designed to take advantage of the benefits of both. A soft decision Viterbi decoder, which is fed with the soft information supplied by the optimal SM decoder, is used at the receiver. A pairwise error probability (PEP) upper bound is derived for the SM-TC scheme in uncorrelated quasi-static Rayleigh fading channels. From the PEP upper bound, code design criteria are given and then used to obtain new 4-, 8- and 16-state SM-TC schemes using quadrature phase-shift keying (QPSK) and 8-ary phase-shift keying (8-PSK) modulations for 2,3 and 4 bits/s/Hz spectral efficiencies. It is shown via computer simulations and also supported by a theoretical error performance analysis that the proposed SM-TC schemes achieve significantly better error performance than the classical space-time trellis codes and coded V-BLAST systems at the same spectral efficiency, yet with reduced decoding complexity.

Hybrid symbols for parallel optical/RF channels using BICM-ID

Novel hybrid symbols for parallel free space optical and radio frequency links using bit-interleaved coded modulation with iterative detection are proposed. An asymptotic bit error performance analysis for the proposed hybrid symbols is developed. The proposed symbol mapping achieves gains of several dBs over conventional mappings.

Performance Analysis of a Novel Double Error Correcting Code for Image Transmission over UWB Channel

In the previous correspondence we introduced a binary double error correcting long code (8 2 5), for 100% data correction. This paper evaluates the BER performance of UWB system using (8 2 5) code over UWB (SV) channel for image transmission. The simulation results presented here uses BPSK, as well as 2dimensional Hermite pulse modulation. Image to be transmitted over UWB channel is compressed by using Huffman coding to achieve lossless compression. The simulink model is developed to implement the basic UWB system without any means for channel correction (equalizer). The receiver is simple correlator instead of rake receiver, which is generally used to combat multipath. The performance of the double error correcting code for UWB communication is evaluated here to achieve 100% accurate image at the receiver. General Terms Wireless Communication

Block LMS-based source localization using range measurement

In this paper, we have proposed an adaptive source localization method. The block LMS method has been used in channel estimation and noise reduction. In this paper, the block LMS method has been used for the source localization and the analysis of the mean square error performance has been carried out in the source localization formulation. The performance of the proposed method has been found to be superior to the existing least squares-based methods under various noise situations. Furthermore, under non-stationary environment, the proposed method can estimate the position without estimating the noise variance.

Symbol Error Performance Analysis of OFDM Relaying System with Subcarrier Mapping Scheme

This letter presents a study on statistical and symbol error performance analysis of the two-hop orthogonal frequency division multiplexing (OFDM) relay link with amplify-and-forward (AF) protocol and subcarrier mapping (SCM) scheme. Closed-form expressions for probability density function (PDF) and symbol error probability (SEP) of the signal-to-noise ratio (SNR) for the kth mapped subcarrier pair link (k-MSPL) are provided. Our asymptotic SEP analysis reveals that the traditional SCM which can maximize the capacity can not improve the average SEP for uncoded OFDM system, however the average SEP can be decreased significantly by dropping several worst links.

Performance analysis of UWB noncoherent receiver with block-coded modulation scheme

Recently, an energy efficient noncoherent receiver scheme, called codeword matching and signal aggregation (CMSA), has been proposed for ultra-wideband (UWB) communications. However, its optimality and analytical error performance have not been studied. This letter shows the CMSA receiver is the optimal receiver in the sense of generalized likelihood ratio test (GLRT) and presents closed-form upper bound expression for bit error probability (BEP).

Performance Analysis of a Complex Multicode Tracking Loop in Bandlimited Rayleigh Fading Channels

This paper presents the root-mean-squared tracking error performance analysis of a class of coherent digital delay-locked loops for multicode direct sequence spread spectrum signals in bandlimited correlated Rayleigh fading channels. In the transmit side, multiple independent PSK-modulated data streams in the in-phase and qudrature phase branches are spread by short mutually orthogonal codes before being further complex spread by a long complex PN code. We assume that the system employs a pilot code channel to assist the receiver's synchronization and channel estimation. The proposed code tracking loop incorporates the pilot-aided channel estimator and derives the timing error from all short-code-spread subchannels. Our analysis takes into account the effects of imperfect channel estimate, correlated frequency selective Rayleigh fading and band-limiting. Numerical results are presented to quantify the impact of the resulting multipath interference within the same code channel and amongst different code channels.

Symbol Error Performance Analysis and Comparison Between Alamouti and MRRC Diversity Combining Scheme for Wireless Communication

The symbol error performance of a wireless communication system is analyzed using diversity combining scheme in Rayleigh fading channels. The performance of the system is compared using Alamouti scheme and maximal-ratio receiver combining (MRRC) scheme. The performance results of the system are evaluated by numerical computation and by simulation using MATLAB. A detailed analysis and exact (closed-form) expressions of the probability of error of the wireless communication systems in Rayleigh fading channels are provided for both M-ary phase-shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM) schemes. Monte Carlo simulation shows exact match with the theoretical results. Keywords: Alamouti scheme; M-PSK; M-QAM; MRRC; Symbol error probability (SEP). © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i1.3000 J. Sci. Res. 2 (1), 54-66 (2010)

Approximate BER Expressions of Distributed Alamouti's Code in Dissimilar Cooperative Networks with Blind Relays

This paper focuses on error performance analysis of distributed Alamouti's code. Recently, many works have been devoted to the performance analysis of this code. In order to simplify the analysis, however, they either assumed the channels in the cooperative network had the same variances or only considered asymptotic error performance at high signal-to-noise ratio (SNR) range. In this paper, we study a general dissimilar cooperative network, where the channels have different variances. Two accurate approximate bit error rate (BER) expressions are proposed in order to evaluate the error performance of the distributed Alamouti's code. We also investigate how the values of channel variances affect the accuracies of the proposed approximate BER expressions. Our results demonstrate that the proposed approximate BER expressions are very close to the exact BER over the whole SNR range. Furthermore, we show that the average BER of the distributed Alamouti's code behaves like (ln(E)/E)2 when the transmission power E is sufficiently large.

Performance Analysis of the Consensus-Based Distributed LMS Algorithm

Low-cost estimation of stationary signals and reduced-complexity tracking of nonstationary processes are well motivated tasks than can be accomplished using ad hoc wireless sensor networks (WSNs). To this end, a fully distributed least mean-square (D-LMS) algorithm is developed in this paper, in which sensors exchange messages with single-hop neighbors to consent on the network-wide estimates adaptively. The novel approach does not require a Hamiltonian cycle or a special bridge subset of sensors, while communications among sensors are allowed to be noisy. A mean-square error (MSE) performance analysis of D-LMS is conducted in the presence of a time-varying parameter vector, which adheres to a first-order autoregressive model. For sensor observations that are related to the parameter vector of interest via a linear Gaussian model and after adopting simplifying independence assumptions, exact closed-form expressions are derived for the global and sensor-level MSE evolution as well as its steady-state (s.s.) values. Mean and MSE-sense stability of D-LMS are also established. Interestingly, extensive numerical tests demonstrate that for small step-sizes the results accurately extend to the pragmatic setting whereby sensors acquire temporally correlated, not necessarily Gaussian data.

Error performance analysis of signal superposition coded cooperative diversity

This paper analyzes the error performance of a coded cooperative diversity system employing the Euclidean superposition of two BPSK-modulated signals. For an example using a convolutional code on block fading channels, the results show excellent agreement with computer simulations. The analysis makes it possible to optimize the power allocation between the local and relay signals numerically, circumventing the need for time consuming Monte Carlo simulations. Similarly, the analysis demonstrates how the power allocation can be tuned to compensate for unbalanced uplink channels and/or to provide unequal error protection to the data from the two cooperating nodes.

A variant of Rotation Forest for constructing ensemble classifiers

Rotation Forest, an effective ensemble classifier generation technique, works by using principal component analysis (PCA) to rotate the original feature axes so that different training sets for learning base classifiers can be formed. This paper presents a variant of Rotation Forest, which can be viewed as a combination of Bagging and Rotation Forest. Bagging is used here to inject more randomness into Rotation Forest in order to increase the diversity among the ensemble membership. The experiments conducted with 33 benchmark classification data sets available from the UCI repository, among which a classification tree is adopted as the base learning algorithm, demonstrate that the proposed method generally produces ensemble classifiers with lower error than Bagging, AdaBoost and Rotation Forest. The bias–variance analysis of error performance shows that the proposed method improves the prediction error of a single classifier by reducing much more variance term than the other considered ensemble procedures. Furthermore, the results computed on the data sets with artificial classification noise indicate that the new method is more robust to noise and kappa-error diagrams are employed to investigate the diversity–accuracy patterns of the ensemble classifiers.

Error probabilities of noncoherent and coherent FSK in the presence of frequency and phase offsets for two-hop relay networks

We analyze the error performance of two-hop relay networks adopting frequency shift keying (FSK) over frequency flat Rayleigh fading channels. It is assumed that relay networks consist of a source, a relay, and a destination without a direct path signal from the source to the destination and the relay adopts the amplify-and-forward protocol with a fixed gain. Firstly, considering imperfect frequency and phase synchronization, we obtain the exact error probability expressions for noncoherent and coherent binary FSK (BFSK). Secondly, assuming perfect frequency and phase synchronization, we derive a closed-form error probability approximation for coherent M-ary FSK (MFSK). The proposed methods can also be used for the error performance analysis of classical one-hop FSK systems with perfect/imperfect frequency and phase synchronization. The obtained error probability expressions will help the design of two-hop relay networks adopting FSK in determining the system parameters such as the transmission power at the source, the amplifying coefficient at the relay, and the maximum affordable frequency and phase offsets to satisfy the required error performance.

Throughput and Error Analysis of a Space-Time Resource Management Scheme for Multi-Gbps Millimeter-Wave WPAN System

In this paper, throughput and error performance analysis is conducted on the proposed space-time resource management (STRM) scheme to realize a multi-Gbps millimeter-wave wireless personal area network (WPAN) system. The proposed STRM allows multiple peer-to-peer communication links to occupy the same time-division-multiple-access (TDMA) time slot, in contrary to the conventional TDMA system that allocates only one time slot to one communication link. Theoretical analysis is performed to investigate the achievable system throughput in the presence of co-channel interference (CCI) generated by communication links co-sharing the same time slot. To increase accuracy, the analysis results are validated by Monte Carlo simulations. Firstly, it is found that the upper bound of the achievable throughput increases linearly with the number of communication links sharing the same time slot. However, optimum throughput exists corresponding to the CCI present in the system. Secondly, by manipulating a parameter that controls the allowable CCI in the network, the system throughput can be optimized. Lastly, it is also found that in a millimeter-wave band system, a victim system with transmitter-receiver separation of 1-meter can achieve bit error rate (BER) of 10- 6 provided that the interferer is at least 6-meters away.

Iterative Joint Tone-Interference Cancellation and Decoding for MIMO-OFDM

In this paper, multi-input-multi-output orthogonal frequency-division multiplexing (MIMO-OFDM) is considered in the presence of multipath fading and multitone interference (MTI). The MIMO-OFDM system makes joint use of channel coding and orthogonal space-frequency block coding (OSFBC) on the transmit side and iterative processing on the receiver side for robustness and improved performance against the fading and MTI effects of the channel. The new iterative receiver is implemented by either an optimal a posteriori probability (APP) space-frequency detector or a soft-information-aided minimum-mean-squared-error (MMSE) combiner at its front end and a soft-input-soft-output channel decoder at its back end. An approximate error performance analysis is provided for the OSFBC-OFDM system under maximum-likelihood decoding to illustrate the interference mitigation efficiency of the system. Then, the two iterative receivers are compared in terms of their computational complexities and bit error rate (BER) performances. As depicted in the BER graphs, both iterative receivers provide an improvement in performance after only a few detection/decoding iterations. It is also shown that despite its suboptimality, the MMSE receiver has the potential to achieve a BER performance close to that of the APP detector at a significantly lower cost.

Levodopa Improves Procedural Motor Learning in Chronic Stroke Patients

Rösser N, Heuschmann P, Wersching H, Breitenstein C, Knecht S, Flöel A. Levodopa improves procedural motor learning in chronic stroke patients. Objective To test the hypothesis that administration of dopamine precursor levodopa improves procedural motor learning (defined as the ability to acquire novel movement patterns gradually through practice) in patients with residual motor deficits in the chronic phase after stroke (≥1y after stroke). Design A double-blind, placebo-controlled, randomized crossover design. Setting Neurology department in a German university. Participants Eighteen patients with chronic motor dysfunction because of stroke (13 men, 5 women; age range, 53–78y; mean time poststroke ± SD, 3.3±2.1y). Intervention Patients received 3 doses of levodopa (100mg of levodopa plus 25mg of carbidopa) or placebo before 1 session of procedural motor learning. Main Outcome Measures Procedural motor learning performed by using the paretic hand assessed by using a modified version of the serial reaction time task with a probabilistic sequence. The primary outcome measure was the difference in reaction times between random and sequential elements. Results Levodopa significantly improved our primary outcome measure, procedural motor learning, compared with placebo ( P<.05). Reaction times to random elements, analysis of error rates, psychophysical assessments, and performance in a simple motor task were comparable between conditions, indicating that better learning under levodopa was not caused by differences in response styles, arousal, mood, or motor reaction times but that levodopa modulated learning. Conclusions Our results show that levodopa may improve procedural motor learning in patients with chronic stroke, in line with our hypothesis. These findings suggest that this interventional strategy in combination with customary rehabilitative treatments could significantly improve the outcome of neurorehabilitation in the chronic stage after stroke. ( Clinicaltrials.gov identifier NCT00126087.)

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation(DPIM), it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation(FDPIM) method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined. with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.

Performance analysis of forward error correcting codes in IPTV

In recent years the forward error correction (FEC) schemes at the binary erasure channel have been researched for many applications including DVB-H and IPTV systems. In most cases the packet-level FEC strategies are implemented by either Reed-Solomon (RS) codes at the link layer or Raptor codes at the application layer. Recently an enhanced decoding method for RS codes was presented. The enhanced-decoding scheme is a combination of erasure and error decoding. In this paper we consider the performance comparison of the enhanced-decoding RS code at the link layer and Raptor code at the application layer in the burst mode transmission to give a guidance of FEC scheme for IPTV application. It is noted that the efficient Raptor decoding algorithm makes it possible to broadcast multimedia data more reliable and faster.

Deterministic Spreading Sequences for the Reverse Link of DS-CDMA With Noncoherent $M$-ary Orthogonal Modulation: Impact and Optimization

M-ary orthogonal modulation with noncoherent detection is an attractive scheme for the reverse link of direct-sequence code-division multiple access (DS-CDMA). The performance analysis of such DS-CDMA systems with random spreading sequences has been thoroughly studied. However, little satisfactory work has been done for systems with deterministic spreading sequences, regardless of their importance from the viewpoint of multiple-access interference reduction. To fill this void, we consider deterministic spreading sequences in this paper. We first present a detailed error performance analysis for the reverse link of DS-CDMA with -ary orthogonal modulation on both additive white Gaussian noise (AWGN) and multipath Rayleigh-fading channels. Then, we formulate the design of spreading sequences for the DS-CDMA system as a nonlinear discrete optimization problem. Two steps are taken to complete the task of sequence optimization: (1) A large code space is generated by permutating a single binary code matrix and imposing a Kronecker product structure on candidate code matrices, and (2) an evolutionary algorithm is applied to efficiently perform optimization. Numerical examples show that the optimized sequences considerably improve the system performance, especially when the number of users is relatively small or an AWGN channel is considered. In addition, our proposed approach can make a good tradeoff between code performance and search complexity.

Stacked OSTBC: Error Performance and Rate Analysis

It is well known that the Alamouti scheme is the only space-time code from orthogonal designs achieving the capacity of a multiple-input multiple-output (MIMO) wireless communication system with n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> =2 transmit antennas and n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> =1 receive antenna. In this paper, we propose the n-times stacked Alamouti scheme for n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> =2n transmit antennas and show that this scheme achieves the capacity in the case of n <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</sub> =1 receive antenna. This result may regarded as an extension of the Alamouti case. For the more general case of more than one receive antenna, we show that if the number of transmit antennas is higher than the number of receive antennas, we achieve a high portion of the capacity with this scheme. Further, we show that the MIMO capacity is at most twice the rate achieved with the proposed scheme for all signal-to-noise ratio (SNR). We derive lower and upper bounds for the rate achieved with this scheme and compare it with upper and lower bounds for the capacity. In addition to the capacity analysis based on the assumption of a coherent channel, we analyze the error rate performance of the stacked orthogonal space-time block code (OSTBC) with the optimal maximum-likelihood (ML) detector and with the suboptimal lattice-reduction (LR)-aided zero-forcing detector. We compare the error rate performance of the stacked OSTBC with spatial multiplexing (SM) and full-diversity achieving schemes. Finally, we illustrate the theoretical results by numerical simulations.