Various Types Of Traffic Research Articles

Modelling, Simulation, and Performance Analysis of Intra-Vehicular Heterogeneous Networks

Vehicles today use a variety of network segments operated by different technologies and protocols within the car (CAN, LIN, Automotive Ethernet, MOST, FlexRay, etc.) to exchange data between different control modules, sensors, and actuators. The exchange of information between other network domains (heterogeneous networks) is enabled through various interconnection points called gateways/bridges. The resulting performance depends on its interconnection structure, network segment traffic aggregation scheme, and medium access technique. Although protocols such as CAN, LIN, FlexRay, and Ethernet have been used in network design for some time, performance modeling and analysis are still needed given the variety of traffic types and sources, new application limitations, and especially the lack of formal verification of network performance for different network scenarios and configurations. This paper presents an end-to-end throughput and delay performance analysis for a reference intra-vehicular network scenario. These models have been validated through simulations in which high correlation values were obtained from 98.7400 to 99.9999, with a low mean square error. The validation cases show that for different LIN, CAN, and Ethernet network configurations, the performance threshold values defined for most current vehicle applications are preserved. However, if the network configuration is modified, the proposed analytical models can be used to formally verify the corresponding performance and delay changes and thus validate whether or not the application requirements are met.

IDMA-based MAC protocol for satellite networks with consideration on channel quality.

In order to overcome the shortcomings of existing medium access control (MAC) protocols based on TDMA or CDMA in satellite networks, interleave division multiple access (IDMA) technique is introduced into satellite communication networks. Therefore, a novel wide-band IDMA MAC protocol based on channel quality is proposed in this paper, consisting of a dynamic power allocation algorithm, a rate adaptation algorithm, and a call admission control (CAC) scheme. Firstly, the power allocation algorithm combining the technique of IDMA SINR-evolution and channel quality prediction is developed to guarantee high power efficiency even in terrible channel conditions. Secondly, the effective rate adaptation algorithm, based on accurate channel information per timeslot and by the means of rate degradation, can be realized. What is more, based on channel quality prediction, the CAC scheme, combining the new power allocation algorithm, rate scheduling, and buffering strategies together, is proposed for the emerging IDMA systems, which can support a variety of traffic types, and offering quality of service (QoS) requirements corresponding to different priority levels. Simulation results show that the new wide-band IDMA MAC protocol can make accurate estimation of available resource considering the effect of multiuser detection (MUD) and QoS requirements of multimedia traffic, leading to low outage probability as well as high overall system throughput.

SE-CAC: A Novel Call Admission Control Scheme for Multi-service IDMA Systems

In this paper a simple and effective call admission control (CAC) scheme is proposed for the emerging interleave-division multiple-access (IDMA) systems, supporting a variety of traffic types and offering different quality of service (QoS) requirements and priority levels. The proposed scheme is signal-to-interference-plus-noise ratio (SINR) evolution based CAC (SE-CAC). The key idea behind the scheme is to take advantage of the SINR evolution technique in the process of making admission decisions, which is developed from the effective chip-by-chip (CBC) multi-user detection (MUD) process in IDMA systems. By virtue of this semi-analytical technique, the MUD efficiency can be estimated accurately. Additionally, the computational complexity can be considerably reduced. These features make the scheme highly suitable for IDMA systems, which can combat intra-cell interference efficiently with simple CBC MUD. Analysis and simulation results show that compared to the traditional CAC scheme considering MUD efficiency as a constant, the proposed SE-CAC scheme can guarantee high power efficiency and throughput for multimedia traffic even in heavy load conditions, illustrating the high efficiency of CBC MUD. Furthermore, based on the SINR evolution, the SE-CAC can make accurate estimation of available resource considering the effect of MUD, leading to low outage probability as well as low blocking and dropping probability.

Wireless Mobile Ad Hoc Networks

Wireless mobile ad hoc networks (MANETs), due to their dynamic nature and due to the unreliability of the wireless medium, pose unique challenges that are significantly more complex than those that arise in traditional wired or even cellular wireless networks. MANETs must self organize into a multihop peer-to-peer network without centralized control and without the help of base stations. Their topologies are unpredictable due to mobility and due to fading, shadowing, and other wireless channel impairments. The number and distribution of active nodes in the network are constantly changing, thereby creating additional variability in the network connectivity. Power and energy constraints, interference, and the shared nature of the wireless medium require adaptive relaying mechanisms and channel access. In such a harsh environment, robustness and quality of service (QoS) are essential. MANETs usually consist of a heterogeneous mixture of nodes with a variety of traffic types and different QoS requirements. Scaling laws for these networks are not fully understood. Diverse tradeoff studies related to capacity, delay, bandwidth, and energy consumption are currently under intense investigation. This special issue, which adds onemore collection of contributions to the vibrant field of ad hoc networking, includes 6 papers that address some of these issues. The first paper by S. Xu et al. investigates the reliability of communications paths in mobile ad hoc networks. They demonstrate an analysis framework for some mobility metrics such as link persistence, link duration, link availability, link residual time, and so forth. The second paper by D. Noh and H. Shin introduces an efficient way to handle service advertisement and discovery in MANETs so as to avoid redundant flooding and to lower overhead. The third paper by M. D. Colagrosso investigates the use of machine learning to facilitate adaptive intelligent broadcasting protocols in MANETs. The forth paper by C. Comaniciu and H. V. Poor introduces a cross-layer design that increases energy efficiency in MANETs through joint optimization of transmit power and routing selection. The fifth paper by L. Qian et al. develops a joint power control and routing algorithm for CDMA in wireless ad hoc networks. The sixth and last paper by E. Perevelov et al. studies scaling laws for ad hoc networks taking into account the overhead in route discovery algorithm.

An analytical QoS service model for delay-based differentiation

The increased need for Quality of Service (QoS) in today's IP networks has concentrated a lot of research and implementation efforts. Carefully designed and managed priority services are essential for quality-demanding traffic, especially in large-scale IP-based environments where aggregation of flows is extensive and a variety of traffic types co-exist. Although individual mechanisms have been widely investigated, not much related work exists on integrated approaches to QoS provisioning that are also feasible to implement. This work presents a thorough approach to the design, dimensioning and provisioning of a high-priority service for high-quality-demanding traffic over an IP network. Our approach employs efficient scheduling and a dynamic admission control scheme while demonstrating an outstanding performance in terms of the quality offered to QoS-demanding traffic. A novel feature is also introduced: while other existing schemes only focus on provisioning of service rate guarantees, ours achieves in addition differentiation of the end-to-end delay perceived by IP flows.

Modelling the self-similar behaviour of network traffic

Traditional Poisson or Markovian traffic models have been proven, by several studies, inappropriate for predicting the performance of networks with long-range dependent traffic. Thus, the use of conventional call admission control algorithms based on short-range dependent models cannot achieve the quality of service required by self-similar sources, since network performance is actually worse in terms of buffer overflow probability and delay. The variety of traffic types that depict long-range dependence creates the need for new models suitable for network design and congestion control mechanisms. In this paper, we present a call admission control (CAC) scheme for traffic with self-similar behaviour based on the notion of effective bandwidth. Our solution satisfies the quality of service requirements of the source, expressed in terms of buffer overflow probability, while taking into account the long-range dependence property of the traffic through the Hurst parameter. We base our CAC mechanism on a Gaussian model initially studied by Norros. We show that this model performs well in the case of one source as well as in the case of many aggregated sources. Our scheme assumes homogenous sources, each one represented by a fractional Gaussian noise process characterised by the mean bit rate and the self-similarity parameters (H, α). We study the estimation of ( H, α) from the real traffic and show the connection between their estimates. Finally, we present a way to calculate the equivalent capacity, which is necessary so that the aggregated stream will achieve the desired loss rate. In our simulation experiments, we used data collected from an IP over ATM high-speed link, connecting the National Research Network of Greece (GRnet) to the Trans-European network backbone (TEN-34), a part of the global Internet.

Buffer losses vs. deadline violations for ABR traffic in an ATM switch: A computational approach

The B?ISDN will carry a variety of traffic types: the Variable Bit Rate traffic (VBR), of which compressed video is an example, Continuous Bit Rate traffic (CBR), of which telemetry is an example, Data traffic, and Available Bit Rate traffic (ABR) that represents aggregate data traffic with very limited guarantees on quality. Of these, VBR and CBR have timing constraints and need synchronous bandwidth; data traffic is relatively delay insensitive. In this paper, we consider the VBR, Data and ABR traffic types and obtain the cumulative distribution function (cdf) of the queueing delay experienced by a burst of ABR traffic in the output buffer of an ATM switch. The cdf is used to trade off buffer loss probabilities against deadline violation probabilities through adjusting the buffer size and (delay) deadline values. Large buffers result in low losses but queueing delays can become excessive and cause a high level of deadline violations. Both losses and violations are detrimental and an operating point must be chosen to achieve a balance. In this paper we study the nature of the trade off. We develop a stochastic Petri net model assuming periodic burst arrivals for VBR and Poisson arrival processes for the Data and ABR traffic types at the burst level, and solve the model analytically (numerically) using a decomposition approach. This decomposition, along with the inherent decomposability of the tagged customer approach for obtaining the cdf opens up a possibility of carrying out fast computations using a parallel machine for selecting the operating point each time that a call is admitted.