Journal of High Speed Networks - Volume 14, issue 3

Authors: Martin, James

Article Type: Research Article

Abstract: We describe and study partially reconfigurable circuit-switched networks. These are dynamic networks in which partial, but not complete, flexibility of resource assignment is retained during the lifetime of a connection. In particular we analyse two examples of partially reconfigurable WDM networks with flexibility of wavelength assignment. In the first example, each connection in the network requires a main lightpath (whose wavelength must remain fixed) and a standby lightpath (whose wavelength may change). In the second example, the network contains two classes of connections with different service levels, one class reconfigurable and the other not. We propose two contrasting reconfiguration algorithms, …and demonstrate that even a small amount of reconfigurability can yield significant performance gains, while a large amount of reconfigurability yields almost all the performance gain that would be attained by introducing complete wavelength conversion to the network. Show more

Keywords: WDM network, wavelength assignment, reconfiguration

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 201-213, 2005

Authors: Guan, Xinping | Yang, Bo | Long, Chengnian | Liu, Zhixin

Article Type: Research Article

Abstract: This paper studies the congestion control in ATM network as a stochastic optimal control problem. Based on the first equivalent controller presented in Automatica 35(12) (1999), 1937–1950, the modified linear quadratic guass (MLQG) control is introduced to control over long-range dependence networks. In addition, the finite impulse response filters employed here compensate the round trip delays as well as smooth transmission rate. Further, we draw a sufficient condition for system stability and analyze the robustness margin along with the maximum tolerable delay from frequency domain technique. With lag compensators satisfactory steady state performance and scalable robustness can be achieved. Also, …we expound the choices of parameters from robustness point of view, which has been related with fairness. Through simulations, the effectiveness of the proposed algorithm is shown as compared with the LQG algorithm. Show more

Keywords: ATM networks, ABR, FARIMA, Filter, time delay, fairness

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 215-226, 2005

Authors: Kim, Kyungjun | Han, Kijun

Article Type: Research Article

Abstract: The IP address lookup in the communication link technologies is becoming a major bottleneck by exploring the exact matching and the parallel hashing in each prefix length. In this paper, we present an algorithm for IP address lookup and collision resolution to reduce memory space and solve collision for high speed routing based on multiple table indexing structure. Our scheme makes possible direct access in a designated IP prefix without replicating the forwarding table entries, and provides efficient collision resolution for fast route lookup with only small memory. Simulation results indicate that our algorithm provides a faster lookup than the …conventional lookup schemes. Show more

Keywords: IP lookup algorithm, high speed router, packet forwarding, routing

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 227-234, 2005

Authors: Khara, S.R. | Tripathi, R.

Article Type: Research Article

Abstract: The design of an efficient MAC protocol is of paramount interest for the definition of wireless ATM (WATM) access. Polling schemes of MAC layer protocol yields reasonably low link channel utilization efficiency and more delay when only small number of mobile stations have packets to transmit. This problem arises from the fact that all the remote units should be polled to know whether remotes have packet to transmit. This paper proposes an efficient algorithm for polling all the remotes currently under base station and bandwidth allocation for information-request packet transfer from remote-to-base direction in MAC layer protocol when only small …number of remote unit (mobile station) awaiting to transmit packets. The mathematical and simulation results show that using proposed technique for slot allocation for information-request packet transfer the MAC overcomes the above inefficiency considerably yielding greater channel utilization efficiency and low delay. Show more

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 235-242, 2005

Authors: Jobin, J. | Faloutsos, Michalis | Tripathi, Satish K.

Article Type: Research Article

Abstract: The goal of this paper is to develop a systematic approach to conducting simulations in wireless cellular networks. Performance analysis in such networks is a non-trivial task for the following reasons. First, there are a lot of parameters whose combined effect needs to be understood. Second, there are no benchmarks or widely accepted realistic values. As a result, different studies use different scenarios, and this makes the results of these studies incomparable. How can we make network scenarios and results easier to interpret and compare? We start with the observation that absolute parameter values are meaningless. Instead, we propose …the use of relative parameters. These parameters combine multiple parameters into fewer parameters; e.g., user speed and diameter of cell are combined into the cell latency parameter. Thus, we reduce the total parameter space, but more importantly, we capture the combined effect of parameters that affect the performance. We show how using relative units of time and space and relative parameters such as cell latency and average number of cells visited can provide better insight than absolute parameters such as session duration or absolute units such as seconds, miles, etc. In addition, we propose the use of steady state utilization, a novel metric that captures the inherent capacity of a mobile network. We show that steady state utilization can become the reference point with which we can conduct meaningful simulations and interpret results more effectively. Finally, we describe a case study to illustrate our methodology. We evaluate the effect of bandwidth reservations on network performance. Our results show how reservations can actually hurt network performance. Show more

Keywords: Simulation, modeling, wireless networks

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 243-262, 2005

Authors: Jagannathan, S.

Article Type: Research Article

Abstract: A novel real-time discrete-event admission control (AC) scheme for high-speed networks is proposed with the aim of attaining a desired quality of service (QoS) and high network utilization. The AC uses the available capacity from a novel adaptive bandwidth estimation scheme, a congestion indicator derived from a congestion controller, Peak bit/cell Rate (PBR/PCR) estimate from new sources, along with the desired QoS metrics, and makes decisions whether to “admit” or “reject” new sources so that the QoS metrics and network utilization are met. The admission controller dynamics are expressed as a discrete-event system while the bandwidth estimator design-based on …Lyapunov theory and the congestion controller dynamics are given in discrete-time. The novel aspect of the proposed approach is the application of hybrid system theory to prove the performance of the proposed admission controller, stability and the development of rigorous and repeatable design procedure. The performance of the proposed AC is evaluated using the QoS metrics, which are given in terms of service delay, packet/cell losses, and network utilization. Simulation results are presented by streaming ON/OFF and MPEG video data into the network. Results show that the proposed AC admits significantly more traffic compared to other available admission control schemes thereby guaranteeing high network utilization while maintaining the desired QoS. Show more

Keywords: Admission control, discrete-event control, traffic estimation, congestion control

Citation: Journal of High Speed Networks, vol. 14, no. 3, pp. 263-281, 2005