Asymmetric Traffic Scenarios Research Articles

Optimal Hybrid Network Coding Scheme Over Two-Way Relaying

The paper introduces a novel hybrid network coding scheme in a three-node two-way relaying network in a wireless fading environment. The proposed hybrid scheme is featured by an opportunistic mechanism which employs one of the two network coding schemes, namely physical-layer network coding (PNC) and digital network coding (DNC), according to the instant rate requirement and dynamic channel condition. We first develop a close-form expression for the power consumption of the proposed scheme, which is further used to formulate a series of optimization problems under both symmetric and asymmetric traffic scenarios. Solving the optimization problems yields important system parameters that determine the optimal power allocations, time split between uplink and downlink transmissions as well as between PNC and DNC, respectively. We will discuss the possible overhead in the real implementation of the proposed scheme. Extensive numerical experiments are conducted to compare the performance of the proposed hybrid scheme with the conventional PNC and DNC scheme, respectively.

Performance analysis of a metro WDM ring networks with variable-length packets under symmetric and asymmetric traffic

In this paper, we discuss and evaluate two proposed metro wavelength division multiplexing (WDM) ring network architectures for variable-length packet traffic in storage area networks (SANs) settings. The paper begins with a brief review of the relevant architectures and protocols in the literature. Subsequently, the network architectures along with their medium access control (MAC) protocols are described. Performance of the two network architectures is studied by means of computer simulation in terms of their queuing delay, node throughput and proportion of packets dropped. The network performance is evaluated under symmetric and asymmetric traffic scenarios with Poisson and self-similar traffic.

Design and performance evaluation of a metro WDM storage area network with IP datagram support

Storage area networks (SANs) are becoming an important part of optical MANs (metropolitan area networks). Growing storage and business-continuity needs; high-bandwidth, low latency requirements for SANs; storage infrastructure consolidation; and post-9/11 regulatory issues are among the several driving factors to push this trend. We, in this paper, consider a metro wavelength division multiplexing (WDM) SAN that allows the transmission of variable packet size such as Internet protocol (IP) datagram and evaluate its performance by means of discrete-event simulation. The network is based on one fixed transmitter and multiple fixed receivers. Beginning with an introduction and the context of this work, we describe the network and node architectures; and introduce the medium access control (MAC) protocols. Subsequently, using the Poisson and self-similar traffic, we present and discuss performance of the proposed network architecture in terms of throughput and queuing delay under symmetric and asymmetric traffic scenarios. The simulation results suggested that the proposed architecture is suitable for SAN applications which demand low queuing delay and high throughput.

Performance Comparison of Time Slot Allocation Schemes in TDD-CDMA Multihop Cellular Networks

Today, high-speed multimedia services are becoming one of the most challenging demands of cellular subscribers. Many approaches have been proposed during last decade and still there are many ongoing researches aiming to provide higher speed and higher quality services for users. Multihop cellular network (MCN) is a promising solution to this problem. MCNs offer high-speed communication to mobile stations which are far from their base stations by relaying their data in a multihop connection. Moreover, TDD-CDMA networks are proven to be able to accommodate the asymmetric traffic generated by applications such as Internet browsers or multimedia applications. These types of traffic are most of the time biased towards uplink or downlink. In this paper we deploy multihop relaying in TDD-CDMA networks in order to provide high data rate connections targeting for multimedia applications. We propose time slot allocation schemes for TDD-CDMA MCNs and compare them with conventional schemes used in TDD-CDMA single-hop cellular networks in terms of users' data rate and maximum capacity in different symmetric and asymmetric traffic scenarios. Results of this study show that our proposed schemes can provide higher data rate as well as capacity and outperform other conventional schemes.

Advantages of Hybrid Input/output Wavelength Conversion in Optical Packet Switches

In this paper, we propose a new Optical Packet Switching Architecture referred to as Shared Per Input/Output Line (SPIOL) in which Wavelength Converters, used to solve output packet contentions, are shared per input and per output line. In this architecture, packets needing conversion can be wavelength translated by converters placed on output lines or by converters placed on input lines. We introduce and discuss the analytical and simulation models we used to evaluate the performance of the architecture in question when a simple control algorithm, referred to as Random Algorithm, is adopted. The proposed architecture performance is compared to that of two other architectures referred to as Shared Per Input Line (SPIL) and Shared per Output Line (SPOL), which share converters per output line only and per input line only, respectively. The comparison is carried out under symmetric and asymmetric traffic scenarios. The obtained results show that in some cases the SPIOL architecture allows for a saving in the order of 20% and 30% with respect to the SPIL and SPOL architectures, respectively.