Performance analysis of finite-buffered asynchronous multistage interconnection networks

In this paper, we present a queueing model for per formance analysis of finite-buffered multistage inter connection networks. The model captures network be havior in an asynchronous communication mode and is based on realistic assumptions. Throughput and de lay are computed using the proposed model and the results are validated via simulation. Various design decisions using this mode! are drawn with respect to delay, throughput, and system power.

A multistage interconnection network (MIN) for multiprocessor systems is proposed. The proposed MIN, called the B-network, uses backward links to provide backward paths for the requests blocked at switches or memory due to contentions. The gamma network is known to contain a cube network (specifically, the inverse omega network) as a substructure. The B-network is obtained from the gamma network by preserving the cube structure but reversing the direction of all other links. These backward links are used as alternate paths for requests blocked due to path or memory contentions. The B-network can be controlled by the simple destination tag control algorithm; packets navigating through the B-network, using both regular forward links and backward links, can reach their destinations under the destination tag control. The performance of the B-network is analyzed under the uniform traffic model and compared to various networks of interest. It is shown that the B-network surpasses the performance of the gamma network, the crossbar switch, and single-buffered MINs based on (2*2) switches, while having the same hardware complexity as the gamma network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Studies issues of multicasting in multistage interconnection networks (MINs) for large-scale multicomputers. In addition to point-to-point communication among the processing nodes, efficient collective communication is critical to the performance of multicomputers. This paper presents a new approach to support multicast communication, on the basis of a restricted address encoding scheme which constructs a short fixed-size multicast header, and a recursive scheme that recycles a multicast packet one or more times through the network to send it to the desire destination nodes. We propose a novel deadlock-free multicast algorithm for multiple multicast packets in MIN-based multicomputers. We also present a performance model for the unbuffered MIN using the multicast algorithm and analyze its performance in terms of the network throughput, where several multicast communications are considered.

Performance analysis of multistage interconnection networks with redundant links

Performance Evaluation of a Class of Multipath Packet Switching Interconnection Networks

A system designed for supporting the network performance analysis and forecast effort is presented, based on the combination of offline network analysis and online real-time performance forecast. The off-line analysis will perform analysis of specific network node performance, correlation analysis of relative network nodes performance and evolutionary mathematical modeling of long-term network performance measurements. The online real-time network performance forecast will be based on one so-called hybrid prediction modeling approach for short-term network, performance prediction and trend analysis. Based on the module design, the system proposed has good intelligence, scalability and self-adaptability, which will offer highly effective network performance analysis and forecast tools for network managers, and is one ideal support platform for network performance analysis and forecast effort.

Multistage interconnection networks are used as a medium for interconnecting processors and memories in multiprocessor systems. Multistage interconnection networks are an effective substitute for crossbar switches, used in telephone network systems and parallel computers, due to their low cost, better performance and easy maintainability. In this paper, we propose new fault-tolerant hybrid multistage interconnection networks obtained from shuffle exchange gamma interconnection network (SEGIN) and logical neighborhood network named as shuffle exchange gamma logical neighborhood interconnection network (SEGLNIN). We evaluated the performance of SEGLNIN in terms of disjoint paths, reliability and hardware cost and compared it with some well-known MINs like shuffle exchange network (SEN), shuffle exchange network with one extra stage (SEN +) and shuffle exchange network with two extra stages (SEN + 2), SEGIN-1, and SEGIN-2. The results illustrate that the performance of the proposed SEGLNIN is better than that of the compared networks in terms of reliability and disjoint paths.

In this paper, we look into a feasible approach to incorporating caches into selected switching ele ments of a multistage interconnection network (MIN)- based multiprocessor. Along with the processor private caches, these switch caches form a two-level cache hi erarchy. Selected switch caches within a particular stage of the MIN are connected by a coherence con trol bus, through which a write-invalidate cache coher ence protocol is maintained. Considering scalability and practicality issues, only limited inclusion between the two cache levels is enforced. A simulation-based performance study is conducted to analyze the impact of the protocol on system performance. Comparison between limited and strict inclusion shows that system performance declines with limited inclusion.

Patel (1981) proposed a probabilistic approach to analyze the performance of synchronous multistage interconnection networks (MINs) based on a uniform reference model and the assumption of independent requests. Patel's model and analytical results have been widely adopted by numerous researchers as a basis to investigate various aspects of MINs. We study in detail the effects of the independence assumption on the accuracy of system performance and point out the factors which cause an inaccuracy. A new queueing model is then proposed and is shown to be very accurate. Since only six states are needed, independent of the size of MINs, this new model is very efficient computationally.

This paper extends previous research efforts related to the simulation performance modelling and analysis of satellite communication networks. Specifically, the use of low earth orbit (LEO) satellite networks for personal communications is examined. Six different satellite constellation configurations are investigated in a packet-switched operating environment. Performance metrics examined are the end-to-end packet delay and the utilization of satellite channels in the dynamic environment. Realistic and accurate models of the physical satellite network and its terrestrial transmitters require that numerous operating characteristics and assumptions be specified. These are based on proposed design requirements of commercial systems, such as Iridium. Via the use of simulation, we show the relative delay and utilization performance of differing satellite network architectures. From these simulation models, mathematical metamodels are derived for the system delays. These innovative models are used to predict the delay performance of different network architectures not previously simulated. Comparison of these metamodels with simulation results show that metamodels provide an accurate means for performance prediction. Copyright © 1999 John Wiley & Sons, Ltd.

We present a two-moment performance analysis of cellular mobile networks with and without channel reservation. Unlike classical analysis where handoff traffic is modeled as Poisson, we characterize handoff traffic as a general traffic process and represent it using the first two moments of its offered traffic. We empirically show that handoff traffic is a smooth process under negative exponential channel holding times. We also show how one may determine customer-oriented grade-of-service parameters such as new-call blocking, handoff call blocking, and forced termination probability under the two-moment representation of traffic offered to each cell. We present extensive results validating our analysis. We compare the performance of the proposed two-moment analysis with classical single-moment analysis and simulation results. Our simulation employs five different mobility models. We show that our proposed model outperforms the existing analytical method when compared to simulation results employing all five mobility models.

This dissertation presents new approaches for cognitive radio networks that combat fading effects and improve detection accuracy. We propose an advance framework for performance analysis of cooperative spectrum sensing over non-identical Nakagami- A detect-amplify-and-forward strategy is proposed to mitigate bandwidth requirements of relaying local observations to a fusion center. The end-to-end performance of a relay-based cooperative spectrum sensing over independent identically distributed Rayleigh fading channels is also investigated in this dissertation. Specifically, we aim to incorporate sensing time, end-to-end SNR, and end-to-end channel statistic into the performance analysis of cooperative CR networks. We also propose a cluster-based cooperative spectrum sensing approach to overcome the bandwidth limitations of the reporting links. The approach reduces the number of reporting terminals to a minimal reporting set and replaces the global fusion center by a local fusion center to mitigate the destructive channel conditions of global relaying channels. A new approach is proposed to select the location of the local fusion center using the general center scheme in graph theory. We aim to show that multipath fading on relaying channels yields similar performance degradations as multipath fading on sensing channels. With the detect-amplify-and forward strategy, refraining the heavily faded relays improves the detection accuracy. A gain of 3 dB is achieved by switching from amplify-and-forward strategy to detect-amplify-and-forward strategy with 3 cooperative users. Compared to the non-cooperative spectrum sensing, a gain of up to 8 dB is achieved with 4 cooperative users and equal gain combining receiver. Similar experimental set up but with selection combining receiver, a gain of 5 dB is achieved.

Summary - This paper presents performance analysis of wireless local area network (WLAN) within the building of the Central Office of Croatian Pension Insurance Institute in Zagreb. The network platform on which the measurement was performed is based on implemented Hewlett Packard Enterprise Aruba wireless system which supports IEEE 802.11 ac (WiFi 5) standard. The observed system topologically counts 51 access points (AP) spread over 6 floors of the physical location together with the associated network system infrastructure as part of the CES local network. The measurement methodology which was used was included number of clients by location of deployed access points, access point loads, wireless network usage, most popular applications used on the network, popular network destinations, measurement of wireless network bandwidth and wireless network total data usage. Collected data were taken in period of 6 months.

This project presents the performance analysis of Wireless Sensor Network (WSN) used in the high-end applications such as weapons sensor ship, biomedical applications, habitat sensing and seismic monitoring. Recently WSN also focuses on national security applications and consumer applications. This project shall demonstrate the performance of WSN models, which are created and simulated using QualNet developer software simulator. Several sensor nodes were uniformly deployed in the networks to create sensing phenomena. The simulation results recorded were the amount of data packets sent and received by each node, the throughput and the delay. All these graphical simulation results from several WSN models will be compared and analyzed separately. Therefore, the important factors and issues pertaining to the WSN performance will also be determined and describe briefly.

This study focuses on performance analysis and optimization of enterprise wireless networks. Fundamental performance parameters of Wi-Fi networks such as signal strength, signal-to-noise ratio (SNR), data rate, and channel interference were evaluated in detail in the study. The analysis process was carried out using Ekahau AI Pro software and Ekahau Sidekick device in a corporate facility, consisting of three main buildings. The obtained data revealed that signal strength dropped to -85 dBm levels in certain areas, negatively affecting the network's coverage area. Particularly in the ground floor of building B-C, secondary signal levels were found to be insufficient for roaming. Across the campus, SNR levels were observed to be 30 dB and above, and these values were found to provide ideal connectivity. During the analysis, it was discovered that in some areas, the number of access points broadcasting signals on the same channel increased up to 6. It has been assessed that this situation may negatively affect network performance in areas where interference is intense. Data rates varied between 1 - 300 Mbps in the 2.4 GHz frequency band and 1 - 585 Mbps in the 5 GHz band. The study provides significant data for performance analysis and optimization of enterprise wireless networks.