IDMA-Based MAC Protocol for Satellite Networks with Consideration on Channel Quality

In order to overcome the shortcomings of existing medium access control (MAC) protocols based on TDMA or CDMA in satellite networks, interleave division multiple access (IDMA) technique is introduced into satellite communication networks. Therefore, a novel wide-band IDMA MAC protocol based on channel quality is proposed in this paper, consisting of a dynamic power allocation algorithm, a rate adaptation algorithm, and a call admission control (CAC) scheme. Firstly, the power allocation algorithm combining the technique of IDMA SINR-evolution and channel quality prediction is developed to guarantee high power efficiency even in terrible channel conditions. Secondly, the effective rate adaptation algorithm, based on accurate channel information per timeslot and by the means of rate degradation, can be realized. What is more, based on channel quality prediction, the CAC scheme, combining the new power allocation algorithm, rate scheduling, and buffering strategies together, is proposed for the emerging IDMA systems, which can support a variety of traffic types, and offering quality of service (QoS) requirements corresponding to different priority levels. Simulation results show that the new wide-band IDMA MAC protocol can make accurate estimation of available resource considering the effect of multiuser detection (MUD) and QoS requirements of multimedia traffic, leading to low outage probability as well as high overall system throughput

Some aspects of traffic control and performance evaluation of ATM networks

The emerging high-speed Asynchronous Transfer Mode (ATM) networks are expected to integrate through statistical multiplexing large numbers of traffic sources having a broad range of statistical characteristics and different Quality of Service (QOS) requirements. To achieve high utilisation of network resources while maintaining the QOS, efficient traffic management strategies have to be developed. This thesis considers the problem of traffic control for ATM networks. The thesis studies the application of neural networks to various ATM traffic control issues such as feedback congestion control, traffic characterization, bandwidth estimation, and Call Admission Control (CAC). A novel adaptive congestion control approach based on a neural network that uses reinforcement learning is developed. It is shown that the neural controller is very effective in providing general QOS control. A Finite Impulse Response (FIR) neural network is proposed to adaptively predict the traffic arrival process by learning the relationship between the past and future traffic variations. On the basis of this prediction, a feedback flow control scheme at input access nodes of the network is presented. Simulation results demonstrate significant performance improvement over conventional control mechanisms. In addition, an accurate yet computationally efficient approach to effective bandwidth estimation for multiplexed connections is investigated. In this method, a feed forward neural network is employed to model the nonlinear relationship between the effective bandwidth and the traffic situations and a QOS measure. Applications of this approach to admission control, bandwidth allocation and dynamic routing are also discussed. A detailed investigation has indicated that CAC schemes based on effective bandwidth approximation can be very conservative and prevent optimal use of network resources. A modified effective bandwidth CAC approach is therefore proposed to overcome the drawback of conventional methods. Considering statistical multiplexing between traffic sources, we directly calculate the effective bandwidth of the aggregate traffic which is modelled by a two-state Markov modulated Poisson process via matching four important statistics. We use the theory of large deviations to provide a unified description of effective bandwidths for various traffic sources and the associated ATM multiplexer queueing performance approximations, illustrating their strengths and limitations. In addition, a more accurate estimation method for ATM QOS parameters based on the Bahadur-Rao theorem is proposed, which is a refinement of the original effective bandwidth approximation and can lead to higher link utilisation

Supporting distributed computation over wide area gigabit networks

The advent of high bandwidth fibre optic links that may be used over very large distances has lead to much research and development in the field of wide area gigabit networking. One problem that needs to be addressed is how loosely coupled distributed systems may be built over these links, allowing many computers worldwide to take part in complex calculations in order to solve "Grand Challenge" problems. The research conducted as part of this PhD has looked at the practicality of implementing a communication mechanism proposed by Craig Partridge called Late-binding Remote Procedure Calls (LbRPC). LbRPC is intended to export both code and data over the network to remote machines for evaluation, as opposed to traditional RPC mechanisms that only send parameters to pre-existing remote procedures. The ability to send code as well as data means that LbRPC requests can overcome one of the biggest problems in Wide Area Distributed Computer Systems (WADCS): the fixed latency due to the speed of light. As machines get faster, the fixed multi-millisecond round trip delay equates to ever increasing numbers of CPU cycles. For a WADCS to be efficient, programs should minimise the number of network transits they incur. By allowing the application programmer to export arbitrary code to the remote machine, this may be achieved. This research has looked at the feasibility of supporting secure exportation of arbitrary code and data in heterogeneous, loosely coupled, distributed computing environments. It has investigated techniques for making placement decisions for the code in cases where there are a large number of widely dispersed remote servers that could be used. The latter has resulted in the development of a novel prototype LbRPC using multicast IP for implicit placement and a sequenced, multi-packet saturation multicast transport protocol. These prototypes show that it is possible to export code and data to multiple remote hosts, thereby removing the need to perform complex and error prone explicit process placement decisions

Protocol security for third generation telecommunication systems

In this thesis, a novel protocol stack architecture is presented. The Future Core Networks System (FCNS) forms a secure reference model for use in packet-switched structures, with its applicability ranging from computer to telecommunication networks. An insight on currently used network protocol systems is given, analysing standardised sets of communication rules with respect to the security they afford to the messages exchanged. The lack of protection schemes for the internal protocol stack messages and the implementation pitfalls of their security architectures are described, in relation to the effects they have on the communication process. The OSI security model is also considered, with disadvantages identified in the placement of security functionality and its management. The drawbacks depicted for currently used systems form the motivation behind this work. The analysis of the FCNS follows, which is composed of three parts. In the first part, the FCNS communication layers are examined, with respect to the mechanisms used to establish, maintain and tear down a connection between peer entities. In the second part, the security mechanisms of the proposed reference architecture are given, including details on the FCNS keystream generator used for the security of the internal FCNS messages. Finally, the FCNS Error Protocol is depicted, illustrating the modes of operation and advantages it exhibits over currently used systems. The work then moves into presenting details of the software FCNS implementation, followed by the presentation of the results and measurements obtained by the case studies created. Comparisons are given in relation to the TCP/IP suite, to provide the means of identifying the FCNS applicability in various network environments. The work is concluded by presenting the FCNS functionality in delivering information for the UMTS, together with further work that may enhance the flexibility and use of the proposed architecture

Security-centric analysis and performance investigation of IEEE 802.16 WiMAX

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The End of Traffic and the Future of Access: A Roadmap to the New Transport Landscape

In most industrialized countries, car travel per person has peaked and the automobile regime is showing considering signs of instability. As cities across the globe venture to find the best ways to allow people to get around amidst technological and other changes, many forces are taking hold — all of which suggest a new transport landscape. Our roadmap describes why this landscape is taking shape and prescribes policies informed by contextual awareness, clear thinking, and flexibility

A Multi-Hop 6LoWPAN Wireless Sensor Network for Waste Management Optimization

In the first part of this Thesis several Wireless Sensor Network technologies, including the ones based on the IEEE 802.15.4 Protocol Standard like ZigBee, 6LoWPAN and Ultra Wide Band, as well as other technologies based on other protocol standards like Z-Wave, Bluetooth and Dash7, are analyzed with respect to relevance and suitability with the Waste Management Outsmart European FP7 Project. A particular attention is given to the parameters which characterize a Large Scale WSN for Smart Cities, due to the amount of sensors involved and to the practical application requested by the project. Secondly, a prototype of sensor network is proposed: an Operative System named Contiki is chosen for its portability on different hardware platforms, its Open Source license, for the use of the 6LoW-PAN protocol and for the implementation of the new RPL routing protocol. The Operative System is described in detail, with a special focus on the uIPv6 TCP/IP stack and RPL implementation. With regard to this innovative routing proto col designed specifically for Low Power Lossy Networks, chapter 4 describes in detail how the network topology is organized as a Directed Acyclic Graph, what is an RPL Instance and how downward and upward routes are constructed and maintained. With the use of several AVR Atmel modules mounting the Contiki OS a real WSN is created and, with an Ultrasonic Sensor, the filling level of a waste basket prototype is periodically detected and transmitted through a multi-hop wireless network to a sink nodeope

Innovative Baggage Delivery Services In Future air transport networks

Airports must accommodate ever increasing passenger numbers while offering a wide range of services. The services are provided through different facilities and processes creat-ing a complex ecosystem of mutually dependent activities. Airport terminals are large-size multi-stakeholder buildings with innovative designs. The complex management of all air-port operations requires proper recognition of all relationships among many stakeholders. The overarching aim of the management and design efforts so to provide high level of passenger satisfaction, and at the same time, to ensure smooth operations with minimum delays. The demands to accommodate increases in passenger numbers drive the need for expanding the capacity of airport and for using the resources and infrastructure more ef-ficiently. The imbalance between the services demand and the available capacity creates congestion problems at different service points throughout the airport. Unlike many other previous works addressing mainly the airport capacity and congestion related to the num-ber of aircraft and flights it is able to serve at any one time, our work is concerned with passenger services, and specifically with baggage delivery. More specifically, the concept of dissociating passenger travel from baggage delivery is introduced and evaluated from several different perspectives. The baggage dissociation can help to improve the passenger air travel experience, make public transport to airport more viable option, and thus, reduce ground-side congestion at airports with reduced CO2 emissions, use existing airport capaci-ty more efficiently while reducing footprint of new airports, optimize monetization of cargo and baggage delivery, elevate the value of non-hub airports, and exploit the new aircraft designs to name a few. It can be argued that innovations in baggage delivery will be man-datory in order to meet the future passenger demands. However, despite these significant drivers, at present, there are still many regulatory and infrastructure challenges which have to be overcome before baggage dissociation can become reality. This thesis contributes sev-eral studies towards feasibility of the baggage dissociation, two ways have been presented to pave the way for the baggage dissociation the new baggage delivery networks and the Satellite terminals (Off-Airport terminals)