Fractional Differential Equations

Radio access technologies for cellular mobile communications are typically characterized by multiple access schemes, e.g., frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and OFDMA. In the 4th generation (4G) mobile communication systems such as Long-Term Evolution (LTE) (Au et al., Uplink contention based SCMA for 5G radio access. Globecom Workshops (GC Wkshps), 2014. doi:10.1109/GLOCOMW.2014.7063547) and LTE-Advanced (Baracca et al., IEEE Trans. Commun., 2011. doi:10.1109/TCOMM.2011.121410.090252; Barry et al., Digital Communication, Kluwer, Dordrecht, 2004), standardized by the 3rd Generation Partnership Project (3GPP), orthogonal multiple access based on OFDMA or single carrier (SC)-FDMA is adopted. Orthogonal multiple access was a reasonable choice for achieving good system-level throughput performance with simple single-user detection. However, considering the trend in 5G, achieving significant gains in capacity and system throughput performance is a high priority requirement in view of the recent exponential increase in the volume of mobile traffic. In addition the proposed system should be able to support enhanced delay-sensitive high-volume services such as video streaming and cloud computing. Another high-level target of 5G is reduced cost, higher energy efficiency and robustness against emergencies.

Non-Orthogonal Multiple Access (NOMA) for cellular future radio access

algorithmics and modular computations, Theory of Codes and Cryptography (3).From an analytical 1. RE Blahut. Theory and practice of error control codes. eecs.uottawa.ca/∼yongacog/courses/coding/ (3) R.E. Blahut,Theory and Practice of Error Control Codes, Addison Wesley, 1983. QA 268. Cached. Download as a PDF 457, Theory and Practice of Error Control CodesBlahut 1984 (Show Context). Citation Context..ontinued fractions.

Theory and practice of error control codes

In order to evaluate the performance of new mobile network technologies, system level simulations are crucial. They aim at determining whether, and at which level predicted link level gains impact network performance. In this paper we present a MATLAB computationally efficient LTE system level simulator. The simulator is offered for free under an academic, noncommercial use license, a first to the authors' knowledge. The simulator is capable of evaluating the performance of the Downlink Shared Channel of LTE SISO and MIMO networks using Open Loop Spatial Multiplexing and Transmission Diversity transmit modes. The physical layer model is based on the postequalization SINR and provides the simulation pre-calculated "fading parameters" representing each of the individual interference terms. This structure allows the fading parameters to be pregenerated offline, vastly reducing computational complexity at run-time.

System Level Simulation of LTE Networks

Research and development of signal processing algorithms for UMTS Long Term Evolution (LTE) requires a realistic, flexible, and standard-compliant simulation environment. To facilitate comparisons with work of other research groups such a simulation environment should ideally be publicly available. In this paper, we present a MATLAB-based downlink physical-layer simulator for LTE. We identify different research applications that are covered by our simulator. Depending on the research focus, the simulator offers to carry out single-downlink, single-cell multi-user, and multi-cell multi-user simulations. By utilizing the Parallel Computing Toolbox of MATLAB, the simulator can efficiently be executed on multi-core processors to significantly reduce the simulation time.

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Simulating the Long Term Evolution physical layer

Impulsive noise occurs frequently in underwater acoustic (UA) channels and can significantly degrade the performance of UA orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we propose two novel compressed sensing based algorithms for joint channel estimation and impulsive noise mitigation in UA OFDM systems. The first algorithm jointly estimates the channel impulse response and the impulsive noise by utilizing pilot subcarriers. The estimated impulsive noise is then converted to the time domain and removed from the received signals. We show that this algorithm reduces the system bit-error-rate through improved channel estimation and impulsive noise mitigation. In the second proposed algorithm, a joint estimation of the channel impulse response and the impulsive noise is performed by exploiting the initially detected data. Then, the estimated impulsive noise is removed from the received signals. The proposed algorithms are evaluated and compared with existing methods through numerical simulations and on real data collected during a UA communication experiment conducted in the estuary of the Swan River, WA, Australia, during December 2015. The results show that the proposed approaches consistently improve the accuracy of channel estimation and the performance of impulsive noise mitigation in UA OFDM communication systems.

Joint Channel Estimation and Impulsive Noise Mitigation in Underwater Acoustic OFDM Communication Systems

In this letter, the modified least mean squares (MLMS) algorithm proposed by Kretschmer is generalized to fractional order $\alpha $ ( $0 ). Such generalization is achieved by replacing the first order difference of the weight updating equation with a fractional one. The convergence speed, weight noise and implementation issue of the generalized MLMS (GMLMS) algorithm are examined. It is shown that for smaller step size, the fractional order $\alpha $ functions the same as the step size, which means that a smaller $\alpha $ will give smaller weight noise while a bigger $\alpha $ will give faster convergence speed.

A Novel Generalization of Modified LMS Algorithm to Fractional Order

Link layer abstraction is crucial to the cross-layer simulation and design as the interface. EESM and MIESM are two kinds of algorithms which account for the instantaneous channel realization and other configurations and obtain the estimated packet error rate correspondingly. Enhanced versions of the algorithms with weighted training are brought out in this paper, which have shown great improvements compared to the original algorithms. Plenty of simulations have been made for verifications and the results show that the enhanced abstraction algorithms can reflect the performance of the link layer of MIMO-OFDM system with high precision for higher layer simulations.

Link Layer Abstraction in MIMO-OFDM System

This letter considers the relay-assisted multiuser downlink transmission with limited feedback in a wireless cellular network. Taking into account the channel quantization errors, we propose two robust linear beamforming schemes at the relay station based on zero forcing (ZF) criterion and minimum mean square error (MMSE) criterion, respectively. It is noted that the channel direction information (CDI) feedback is sufficient for determining the beamforming vectors in our proposed schemes, which reduces the feedback load. Simulation results show that compared with the conventional ZF beamforming and MMSE beamforming in limited feedback systems, the proposed precoding schemes achieve an improvement in the average bit error rate (BER) performance of the system.

Robust Linear Beamforming for MIMO Relay Broadcast Channel With Limited Feedback

Multimedia Broadcast/Multicast Service (MBMS) provides efficient solution for multimedia broadcasting services by distributing resources among a group of subscribers. Different from previous broadcasting services, MBMS subscribers will send feedback information which can be used to improve system performance by adapting resource allocation to channel state. In this paper in LTE frameworks we propose a Frequency Domain Packet Scheduling (FDPS) algorithm for MBMS, in which resource blocks are dynamically allocated to MBMS based on knowledge of instantaneous channel condition. The objective is to optimize system throughput performance while guaranteeing system coverage. This paper examines the algorithm in details with different (Channel Quality Indicator) CQI reporting modes, alterable frequency bandwidth for MBMS and different numbers of MBMS subscribers per sector. Simulations show that comparing to a simple blind FDPS algorithm, the proposed algorithm improves system throughput without sacrificing coverage.

Zhiqiang He

Papers

Joint Channel Estimation and Impulsive Noise Mitigation in Underwater Acoustic OFDM Communication Systems

A Novel Generalization of Modified LMS Algorithm to Fractional Order

Link Layer Abstraction in MIMO-OFDM System

Robust Linear Beamforming for MIMO Relay Broadcast Channel With Limited Feedback

Channel-Aware Frequency Domain Packet Scheduling for MBMS in LTE