State Markov Channel Research Articles

A Novel Analytical Framework for Integrated Cross-Layer Study of Call-Level and Packet-Level QoS in Wireless Mobile Multimedia Networks

We present a novel integrated analytical framework for analyzing the quality-of-service (QoS) performance measures in a wireless mobile multimedia network. The framework integrates physical, radio link, and network layer parameters and protocols to analyze the call-level and packet-level performances. In the network layer, call admission control (CAC) is responsible for deciding whether an incoming call can be accepted or not so that the performances of the ongoing calls do not deteriorate below the acceptable level. Also, an adaptive channel allocation (ACA) scheme is used to maximize the utilization of the radio resources. In the data link layer, queue management and error control are used for non-real-time loss-sensitive traffic. In the physical layer, a finite state Markov channel (FSMC) is used to model channel fading, and adaptive modulation is used for rate adaptation according to channel quality. Various call-level and packet-level QoS measures for real-time, non-real-time, and best-effort traffic are obtained. The analytical results are validated by extensive simulations. Examples of the applications of the presented analytical framework are also provided

An average error probability evaluation in a fading environment using finite state Markov channel for LEO satellite communication system

Recent research shows that fading channels have a much larger capacity than anticipated with traditional approaches. This modern view on fading channels encouraged us to characterize these channels more precisely for better identification and use of wireless channel capacity. Since the Markov model is a natural way to approximate a channel with memory, many people have considered finite state first-order Markov modeling for describing a wireless communication channel. In this paper, we first introduce the relationship between a physical fading channel and the corresponding finite state Markov Model (FSMC) in case of low earth orbit (LEO) satellite communication system, which can be used for performance evaluation in an M -order quadrature amplitude-modulation (MQAM) transmission scheme by deriving an analytical expression of average bit error rate in Rayleigh fading channel. By establishing the FSMC, we show that the FSMC is accurate enough to evaluate the performance of MQAM modulation scheme to be implemented on board a LEO satellite communication system.

An Efficient Transmission Slot Selection Scheme for MC-CDMA Systems with Packet Loss and Delay Bound Constraints

In this letter, we propose an efficient transmission slot selection scheme for Band Division Multi-Carrier-CDMA (BD-MC-CDMA) systems under the constraints of packet loss and delay bound for each individual session. By utilizing channel dynamics together with the delay deadline and loss history, one can determine whether to transmit or not during each time slot, based on the prediction of future channel variations. To validate the efficiency of the proposed algorithm, we model each sub-band as a discrete time Markov Chain using a finite state Markov channel (FSMC) and derive the criteria required for transmission decision. Simulation results show that our proposed scheme can satisfy quality of service (QoS) requirements for real-time traffic with minimum use of resources, while increasing throughput of non-real-time traffic with the resources saved from real-time traffic.

Discrete Rayleigh fading channel modeling

AbstractIn order to understand the behaviour of upper‐layer protocols and to design or fine tune their parameters over wireless networks, it is common to assume that the underlying channel is a flat Rayleigh fading channel. Such channels are commonly modeled as finite state Markov chains. Recently, hidden Markov models have also been employed to characterize these channels. In this paper, we study the different models that have been proposed along with the analysis of their validity. We start by presenting some preliminary concepts related to the modeling of the wireless communications channel. We then proceed to introduce finite state Markov channel models (FSMCs) along with the relations between them and the modulation schemes, error control protocols and channel coding. We propose and study the effects of taking into account the fading process in its characterization. We finish with a discussion on hidden Markov models for Rayleigh fading channel modeling. Copyright © 2004 John Wiley & Sons, Ltd.

Matching pursuits multiple description coding for wireless video

Multiple description coding (MDC) is an error-resilient source coding scheme that creates multiple bitstreams of approximately equal importance. The reconstructed signal based on any single bitstream has an acceptable quality. However, a higher quality reconstruction can be achieved with a larger number of bitstreams. We develop a multiple description video coding scheme based on a three-loop structure. We modify the discrete cosine transform structure to the matching pursuits framework and evaluate performance gain using maximum-likelihood (ML) enhancement when both descriptions are available. We find that ML enhancement works best for low motion sequences and results in gains of up to 1.3 dB in terms of average PSNR. Rate distortion performance is characterized. Performance comparison is made between our MDC scheme and single description coding (SDC) schemes over lossy channels, including two state Markov channels and Rayleigh fading channels. We find that MDC outperforms SDC in bursty slowly varying environments. In the case of Rayleigh fading channels, interleaving helps SDC close the gap and even outperform MDC depending on the amount of interleaving performed, at the expense of additional delay.

An energy-efficient power control approach for WLANs

In this paper we consider the problem of reducing energy consumption during the transmission phase in WLANs. We found that for a given network configuration, channel characteristics, and packet length, an optimum RF transmission power level exists which assures a minimum energy expenditure for the actually transmitted bit of information. Based on this observation, we present a packet length dependent power control mechanism. We performed discrete event simulations of an IEEE 802.11 LAN in ad hoc mode using a two state Markov channel model. The achieved simulation results indicate a significant potential for energy saving. We also present a workable approach for choosing the most energy-saving RF transmit power level which is based on the perceived packet error rate of a single mobile.

Sequence detection and channel state estimation over finite state Markov channels

A useful model for general time-varying channels is a finite state Markov chain. In this paper, maximum likelihood sequence estimation (MLSE) for signals over finite state Markov channels (FSMCs) is studied. Also studied is the maximum a posteriori (MAP) channel state estimation. When coded signals with interleaving are transmitted, the channel estimates can be used to make soft-decision decoding. The error performance of the proposed sequence and channel state estimation schemes are evaluated through computer simulations. The effect of channel modeling error is also discussed.

Variable order Markov modellingfor LEO mobile satellite channels

A finite state Markov channel (FSMC) model for a digital narrowband mobile LEO satellite channel is presented, which can be used to predict the time-varying behaviour of the channel and to adapt the transmission to the channel state. The model is developed with the help of the so-called context tree pruning (CTP) algorithm. Its effectiveness is demonstrated by comparing theoretical results concerning the digital channel with simulated results obtained from time-continuous channel models.

A Markov Based Detection for Broadband over Power Line Communications (PLC)

Successful development of Broadband over Power Lines (BPL) is obviously a potential solution for wireless communication systems with the existing infrastructure. Multi-Carrier Code Division Multiple Access (MC-CDMA) with Orthogonal Frequency Division Multiplexing (OFDM) modulation technique is a promising solution for a frequency selective fading with impulsive noises of the PLC channel. A linear iterative receiver with a Finite State Markov Channel (FSMC) model is proposed to remove Multiple Access Interference (MAI) and Inter Symbol Interferences (ISI). In this paper we focused on Maximum Likelihood (ML) feedback detection by introducing FSMC to get significant improvement in Bit Error Rate (BER). This model of the receiver is more robust against Gaussian colored and impulsive noises of the PLC channel. Keywords: FSMC; MC-CDMA; OFDM; MAI; ISI DOI: 10.3329/bjsir.v44i4.4595 Bangladesh J. Sci. Ind. Res. 44(4), 441-444, 2009