Extremely high data-rate, reliable network systems research

Significant progress was made over the year in the four focus areas of this research group: gigabit protocols, extensions of metropolitan protocols, parallel protocols, and distributed simulations. Two activities, a network management tool and the Carrier Sensed Multiple Access Collision Detection (CSMA/CD) protocol, have developed to the point that a patent is being applied for in the next year; a tool set for distributed simulation using the language SIMSCRIPT also has commercial potential and is to be further refined. The year's results for each of these areas are summarized and next year's activities are described

An Architecture for distributed multimedia database systems

In the past few years considerable demand for user oriented multimedia information systems has developed. These systems must provide a rich set of functionality so that new, complex, and interesting applications can be addressed. This places considerable importance on the management of diverse data types including text, images, audio and video. These requirements generate the need for a new generation of distributed heterogeneous multimedia database systems. In this paper we identify a set of functional requirements for a multimedia server considering database management, object synchronization and integration, and multimedia query processing. A generalization of the requirements to a distributed system is presented, and some of our current research and developing activities are discussed

Medium access control mechanisms for high speed metropolitan area networks

In this dissertation novel Medium Access Control mechanisms for High Speed Metropolitan Area networks are proposed and their performance is investigated under the presence of single and multiple priority classes of traffic. The proposed mechanisms are based on the Distributed Queue Dual Bus network, which has been adopted by the IEEE standardization committee as the 802.6 standard for Metropolitan Area Networks, and address most of its performance limitations. First, the Rotating Slot Generator scheme is introduced which uses the looped bus architecture that has been proposed for the 802.6 network. According to this scheme the responsibility for generating slots moves periodically from station to station around the loop. In this way, the positions of the stations relative to the slot generator change continuously, and therefore, there are no favorable locations on the busses. Then, two variations of a new bandwidth balancing mechanism, the NSW_BWB and ITU_NSW are introduced. Their main advantage is that their operation does not require the wastage of channel slots and for this reason they can converge very fast to the steady state, where the fair bandwidth allocation is achieved. Their performance and their ability to support multiple priority classes of traffic are thoroughly investigated. Analytic estimates for the stations\u27 throughputs and average segment delays are provided. Moreover, a novel, very effective priority mechanism is introduced which can guarantee almost immediate access for high priority traffic, regardless of the presence of lower priority traffic. Its performance is thoroughly investigated and its ability to support real time traffic, such as voice and video, is demonstrated. Finally, the performance under the presence of erasure nodes of the various mechanisms that have been proposed in this dissertation is examined and compared to the corresponding performance of the most prominent existing mechanisms

High speed protocols for dual bus and dual ring network architectures

In this dissertation, two channel access mechanisms providing fair and bandwidth efficient transmission on dual bus and dual ring networks with high bandwidth-latency product are proposed. In addition, two effective priority mechanisms are introduced to meet the throughput and delay requirements of the diverse arrays of applications that future high speed networks must support. For dual bus architectures, the Buffer Insertion Bandwidth Balancing (BI_BWB) mechanism and the Preemptive priority Bandwidth Balancing (P_BI_BWB) mechanism are proposed. BI_BWB can significantly improve the delay performance of remote stations. It achieves that by providing each station with a shift register into which the station can temporarily store the upstream stations\u27 transmitted packets and replace these packets with its own transmissions. P_BI_BWB, an enhancement of BI_BWB, is designed to introduce effective preemptive priorities. This mechanism eliminates the effect of low priority on high priority by buffering the low priority traffic into a shift register until the transmission of the high priority traffic is complete. For dual ring architectures, the Fair Bandwidth Allocation Mechanism (FBAM) and the Effective Priority Bandwidth Balancing (EP_BWB) mechanism are introduced. FBAM allows stations to reserve channel bandwidth on a continuous basis rather than wait until bandwidth starvation is observed. Consequently, FBAM does not have to deal with the difficult issue of identifying starvation, a serious drawback of other access mechanisms such as the Local and Global Fairness Algorithms (LFA and GFA, respectively). In addition, its operation requires a significantly smaller number of control bits in the access control field of the slot and its performance is less sensitive to system parameters. Moreover, FBAM demonstrates Max-Min flow control properties with respect to the allocation of bandwidth among competing traffic streams, which is a significant advantage of FBAM over all the previously proposed channel access mechanisms. EP_BWB, an enhancement of FBAM to support preemptive priorities, minimizes the effect of low priority on high priority and supports delay-sensitive traffic by enabling higher priority classes to preempt the transmissions of lower priority classes. Finally, the great potential of EP_BWB to support the interconnection of base stations on a distributed control wireless PCN carrying voice and data traffic is demonstrated

Performance Improvements for FDDI and CSMA/CD Protocols

The High-Performance Computing Initiative from the White House Office of Science and Technology Policy has defined 20 major challenges in science and engineering which are dependent on the solutions to a number of high-performance computing problems. One of the major areas of focus of this initiative is the development of gigabit rate networks to be used in environments such as the space station or a National Research and Educational Network (NREN). The strategy here is to use existing network designs as building blocks for achieving higher rates, with the ultimate goal being a gigabit rate network. Two strategies which contribute to achieving this goal are examined in detail.1 FDDI2 is a token ring network based on fiber optics capable of a 100 Mbps rate. Both media access (MAC) and physical layer modifications are considered. A method is presented which allows one to determine maximum utilization based on the token-holding timer settings. Simulation results show that employing the second counter-rotating ring in combination with destination removal has a multiplicative effect greater than the effect which either of the factors have individually on performance. Two 100 Mbps rings can handle loads in the range of 400 to 500 Mbps for traffic with a uniform distribution and fixed packet size. Performance is dependent on the number of nodes, improving as the number increases. A wide range of environments are examined to illustrate robustness, and a method of implementation is discussed

Dynamic Spectrum Sharing in Cognitive Radio Networks Using Truthful Mechanisms and Virtual Currency

In cognitive radio networks, there are scenarios where secondary users (SUs) utilize opportunistically the spectrum originally allocated to primary users (PUs). The spectrum resources available to SUs fluctuates over time due to PUs activity, SUs mobility and competition between SUs. In order to utilize these resources efficiently spectrum sharing techniques need to be implemented. In this paper we present an approach based on game-theoretical mechanism design for dynamic spectrum sharing. Each time a channel is not been used by any PU, it is allocated to SUs by a central spectrum manager based on the valuations of the channel reported by all SUs willing to use it. When an SU detects a free channel, it estimates its capacity according to local information and sends the valuation of it to the spectrum manager. The manager calculates a conflict-free allocation by implementing a truthful mechanism. The SUs have to pay for the allocation an amount which depends on the set of valuations. The objective is not to trade with the spectrum, but to share it according to certain criteria. For this, a virtual currency is defined and therefore monetary payments are not necessary. The spectrum manager records the credit of each SU and redistributes the payments to them after each spectrum allocation. The mechanism restricts the chances of each SU to be granted the channel depending on its credit availability. This credit restriction provides an incentive to SUs to behave as benefit maximizers. If the mechanism is truthful, their best strategy is to communicate the true valuation of the channel to the manager, what makes possible to implement the desired spectrum sharing criteria. We propose and evaluate an implementation of this idea by using two simple mechanisms which are proved to be truthful, and that are tractable and approximately efficient. We show the flexibility of these approach by illustrating how these mechanisms can be modified to achieve different sharing objectives which are trade-offs between efficiency and fairness. We also investigate how the credit restriction and redistribution affects the truthfulness of these mechanisms.This work was supported by the Spanish government through Projects TIN 2008-06739-C04-02 and TIN 2010-21378-C02-02.Vidal Catalá, JR.; Pla, V.; Guijarro Coloma, LA.; Martínez Bauset, J. (2013). Dynamic Spectrum Sharing in Cognitive Radio Networks Using Truthful Mechanisms and Virtual Currency. Ad Hoc Networks. 11:1858-1873. https://doi.org/10.1016/j.adhoc.2013.04.010S185818731

Design and implementation of high speed multimedia network.

by Yeung Chung Toa.Thesis (M.Phil.)--Chinese University of Hong Kong, 1994.Includes bibliographical references (leaves 63-[65]).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Bandwidth required by multimedia applications --- p.1Chapter 1.2 --- Real-time requirement --- p.2Chapter 1.3 --- Multicasting --- p.2Chapter 1.4 --- Other networks --- p.3Chapter 1.5 --- Overview of CUM LAUDE NET --- p.5Chapter 1.5.1 --- Protocols --- p.7Chapter 1.5.2 --- Network Services --- p.8Chapter 1.6 --- Scope of the Thesis --- p.9Chapter 2 --- Network Architecture --- p.11Chapter 2.1 --- CUM LAUDE NET Architectural Overview --- p.11Chapter 2.2 --- Level One Network Architecture --- p.12Chapter 2.3 --- Level-One Router --- p.14Chapter 2.3.1 --- packet forwarding --- p.14Chapter 2.3.2 --- packet insertion --- p.15Chapter 2.3.3 --- packet removal --- p.15Chapter 2.3.4 --- fault protection --- p.15Chapter 2.4 --- Hub --- p.16Chapter 2.5 --- Host & Network Interface Card --- p.17Chapter 3 --- Protocol --- p.19Chapter 3.1 --- Design Overview --- p.19Chapter 3.2 --- Layering --- p.20Chapter 3.3 --- "Segment, Datagram, and Packet Format" --- p.21Chapter 3.3.1 --- IP/VCI field --- p.23Chapter 3.4 --- Data Link --- p.23Chapter 3.4.1 --- byte format and data link synchronization --- p.23Chapter 3.4.2 --- access control byte --- p.24Chapter 3.4.3 --- packet/frame boundary --- p.26Chapter 3.5 --- Fast Packet Routing Protocol --- p.26Chapter 3.5.1 --- Level-2/Level-l Bridge/Router --- p.27Chapter 3.5.2 --- Level-1 Hub --- p.29Chapter 3.5.3 --- Local Host NIC --- p.29Chapter 3.6 --- Media Access Control Protocol I : ACTA --- p.30Chapter 3.7 --- Media Access Control Protocol II: Hub Polling --- p.34Chapter 3.8 --- Protocol Implementation on CUM LAUDE NET --- p.36Chapter 4 --- Hardware Implementation & Performance of Routers and NIC --- p.40Chapter 4.1 --- Functionality of Router --- p.40Chapter 4.2 --- Important Components Used in the Router Design --- p.43Chapter 4.2.1 --- TAXI Transmitter and Receiver --- p.43Chapter 4.2.2 --- First-In-First-Out Memory (FIFO) --- p.44Chapter 4.3 --- Design of Router --- p.45Chapter 4.3.1 --- Version 1 --- p.45Chapter 4.3.2 --- Version 2 --- p.47Chapter 4.3.3 --- Version 3 --- p.50Chapter 4.4 --- Lessons Learned from the High Speed Router Design --- p.57Chapter 5 --- Conclusion --- p.61Bibliography --- p.6

On the accurate performance evaluation of the LTE-A random access procedure and the access class barring scheme

[EN] The performance evaluation of the random access (RA) in LTE-A has recently become a major research topic as these networks are expected to play a major role in future 5G networks. Up to now, the key performance indicators (KPIs) of the RA in LTE-A have been obtained either by performing a large number of simulations or by means of analytic models that, oftentimes, sacrifice precision in exchange for simplicity. In this paper, we present an analytical model for the performance evaluation of the LTE-A RA procedure that incorporates the access class barring (ACB) scheme. By means of this model, each and every one of the KPIs suggested by the 3GPP can be obtained with minimal error when compared with results obtained by simulation. To the best of our knowledge, this paper presents the most accurate analytical model, which can be easily adapted to incorporate modifications of network parameters and/or extensions to the LTE-A system. In addition, our model of the ACB scheme can be easily incorporated to other analytic models of similar nature without further modifications.This work was supported in part by the Ministry of Economy and Competitiveness of Spain under Grant TIN2013-47272-C2-1-R and Grant TEC2015-71932-REDT. The research of I. Leyva-Mayorga was supported under Grant 383936 CONACYT-Gobierno del Estado de Mexico 2014. The research of L. Tello-Oquendo was supported in part by Programa de Ayudas de Investigacion y Desarrollo, Universitat Politecnica de Valencia.Leyva-Mayorga, I.; Tello-Oquendo, L.; Pla, V.; Martínez Bauset, J.; Casares-Giner, V. (2017). On the accurate performance evaluation of the LTE-A random access procedure and the access class barring scheme. IEEE Transactions on Wireless Communications. 16(12):7785-7799. https://doi.org/10.1109/TWC.2017.2753784S77857799161