High speed all optical networks

An inherent problem of conventional point-to-point wide area network (WAN) architectures is that they cannot translate optical transmission bandwidth into comparable user available throughput due to the limiting electronic processing speed of the switching nodes. The first solution to wavelength division multiplexing (WDM) based WAN networks that overcomes this limitation is presented. The proposed Lightnet architecture takes into account the idiosyncrasies of WDM switching/transmission leading to an efficient and pragmatic solution. The Lightnet architecture trades the ample WDM bandwidth for a reduction in the number of processing stages and a simplification of each switching stage, leading to drastically increased effective network throughputs. The principle of the Lightnet architecture is the construction and use of virtual topology networks, embedded in the original network in the wavelength domain. For this construction Lightnets utilize the new concept of lightpaths which constitute the links of the virtual topology. Lightpaths are all-optical, multihop, paths in the network that allow data to be switched through intermediate nodes using high throughput passive optical switches. The use of the virtual topologies and the associated switching design introduce a number of new ideas, which are discussed in detail

Challenges of Implementing Automatic Dependent Surveillance Broadcast in the Nextgen Air Traffic Management System

The Federal Aviation Administration is in the process of replacing the current Air Traffic Management (ATM) system with a new system known as NextGen. Automatic Dependent Surveillance-Broadcast (ADS-B) is the aircraft surveillance protocol currently being introduced as a part of the NextGen system deployment. The evolution of ADS-B spans more than two decades, with development focused primarily on increasing the capacity of the Air Traffic Control (ATC) system and reducing operational costs. Security of the ADS-B communications network has not been a high priority, and the inherent lack of security measures in the ADS-B protocol has come under increasing scrutiny as the NextGen ADS-B implementation deadline draws near. The research conducted in this thesis summarizes the ADS-B security vulnerabilities that have been under recent study. Thereafter, we survey both the theoretical and practical efforts which have been conducted concerning these issues, and review possible security solutions. We create a classification of the ADS-B security solutions considered and provide a ranking of the potential solutions. Finally, we discuss the most compatible approaches available, given the constraints of the current ADS-B communications system and protocol

SIMULATIVE ANALYSIS OF ROUTING AND LINK ALLOCATION STRATEGIES IN ATM NETWORKS

For Broadband Integrated Services Digital (B-ISDN) networks ATM is a promising technology, because it supports a wide range of services with different bandwidth demands, traffic characteristics and QoS requirements. This diversity of services makes traffic control in these networks much more complicated than in existing circuit or packet switched networks. Traffic control procedures include both actions necessary for setting up virtual connections (VC), such as bandwidth assignment, call admission, routing and resource allocation and congestion control measures necessary to maintain throughput in overload situations. This paper deals with routing and link allocation, and analyses the performance of such algorithms in terms of call blocking probability, link capacity utilization and QoS parameters. In our model the network carries out the following steps when a call is offered to the network: (1) Assign an appropriate bandwidth to an offered call (Bandwidth assignment) (2) Find a transmission path between the source and destination with enough available transmission capacity (Routing) (3) Allocate resource along that path (Link allocation) We consider an example 5-node network [7], conduct an extensive survey of routing, and link allocation algorithms. Regarding step (1) we employ the equivalent link capacity assignment presented by various interesting papers [1]-[5]. We find that the choice of routing and link allocation algorithms has a great impact on network performance, and that different routing algorithms perform best under different network load values. Shortest path routing (SPR) is a good candidate for low, alternate routing (AR) for medium and non-alternate routing (NAR) for high traffic load values. Concerning link allocation strategies, we find that partial overlap (POL) strategies that seem to be able to present near optimal performance are superior to complete sharing (CS) and complete partitioning (CP) strategies. As a further improvement of the POL scheme, we propose a 2-level link allocation algorithm, which yields highest link utilization. In this scheme, not only the accesses of different service classes to different virtual paths (VPs) are controlled, but also an individual VP's transmission capacity is optimally allocated to the service classes according to their bandwidth requirements in order to assure high link utilization. This method seems to be adjustable to the fine degree of granularity of bandwidth demands in B-ISDN networks. It is shown that in order to minimize cell loss the call level resource allocation plays a significant role: networks with the same buffer size switches display different cell loss probabilities in the nodes and impose different end-to-end delay on cells if the link allocation and routing differ. Again, we find that when traffic is tolerable by the network, SPR causes the least cell loss. This can be explained by the fact that SPR spreads the incoming calls in the network. It eagerly seeks new routes instead of utilizing the already used but still not congested routes. SPR obviously wastes more rapidly link and buffer capacity as traffic load becomes higher than the AR, which chooses a new route only when it has to, i.e. when the route of higher priority becomes congested. That is why we experience that as soon as the SPR starts loosing cells, it indicates that available resources have been consumed and it rapidly goes up to very high blocking probabilities after a small further increase of load

ATM network impairment to video quality

Includes bibliographical reference

Quality of Service Controlled Multimedia Transport Protocol

PhDThis research looks at the design of an open transport protocol that supports a range of services including multimedia over low data-rate networks. Low data-rate multimedia applications require a system that provides quality of service (QoS) assurance and flexibility. One promising field is the area of content-based coding. Content-based systems use an array of protocols to select the optimum set of coding algorithms. A content-based transport protocol integrates a content-based application to a transmission network. General transport protocols form a bottleneck in low data-rate multimedia communicationbsy limiting throughpuot r by not maintainingt iming requirementsT. his work presents an original model of a transport protocol that eliminates the bottleneck by introducing a flexible yet efficient algorithm that uses an open approach to flexibility and holistic architectureto promoteQ oS.T he flexibility andt ransparenccyo mesi n the form of a fixed syntaxt hat providesa seto f transportp rotocols emanticsT. he mediaQ oSi s maintained by defining a generic descriptor. Overall, the structure of the protocol is based on a single adaptablea lgorithm that supportsa pplication independencen, etwork independencea nd quality of service. The transportp rotocol was evaluatedth rougha set of assessmentos:f f-line; off-line for a specific application; and on-line for a specific application. Application contexts used MPEG-4 test material where the on-line assessmenuts eda modified MPEG-4 pl; yer. The performanceo f the QoSc ontrolledt ransportp rotocoli s often bettert hano thers chemews hen appropriateQ oS controlledm anagemenatl gorithmsa re selectedT. his is shownf irst for an off-line assessmenwt here the performancei s compared between the QoS controlled multiplexer,a n emulatedM PEG-4F lexMux multiplexers chemea, ndt he targetr equirements. The performanceis also shownt o be better in a real environmentw hen the QoS controlled multiplexeri s comparedw ith the real MPEG-4F lexMux scheme