Call admission control for interactive multimedia satellite networks.

Master of Science in Engineering (Electronic). University of KwaZulu-Natal, Durban 2015.Satellite communication has become an integral component of global access communication network due mainly to its ubiquitous coverage, large bandwidth and ability to support for large numbers of users over fixed and mobile devices. However, the multiplicity of multimedia applications with diverse requirements in terms of quality of service (QoS) poses new challenges in managing the limited and expensive resources. Furthermore, the time-varying nature of the propagation channel due to atmospheric and environmental effects also poses great challenges to effective utilization of resources and the satisfaction of users’ QoS requirements. Efficient radio resource management (RRM) techniques such as call admission control (CAC) and adaptive modulation and coding (AMC) are required in order to guarantee QoS satisfaction for user established connections and realize maximum and efficient utilization of network resources. In this work, we propose two CAC policies for interactive satellite multimedia networks. The two policies are based on efficient adaptation of transmission parameters to the dynamic link characteristics. In the first policy which we refer to as Gaussian Call Admission Control with Link Adaptation (GCAC-LA), we invoke the central limit theorem to statistically multiplex rate based dynamic capacity (RBDC) connections and obtain an aggregate bandwidth and required capacity for the multiplex. Adaptive Modulation and Coding (AMC) is employed for transmission over the time-varying wireless channel of the return link of an interactive satellite network. By associating users’ channel states to particular transmission parameters, the amount of resources required to satisfy user connection requirements in each state is determined. Thus the admission control policy considers in its decision, the channel states of all existing and new connections. The performance of the system is investigated by simulation and the results show that AMC significantly improves the utilization and call blocking performance by more than twice that of a system without link adaptation. In the second policy, a Game Theory based CAC policy with link adaptation (GTCAC-LA) is proposed. The admission of a new user connection under the GTCAC-LA policy is based on a non-cooperative game that is played between the network (existing user connections) and the new connection. A channel prediction scheme that predicts the rain attenuation on the link in successive intervals of time is also proposed. This determines the current resource allocation for every source at any point in time. The proposed game is played each time a new connection arrives and the strategies adopted by players are based on utility function, which is estimated based on the required capacity and the actual resources allocated. The performance of the CAC policy is investigated for different prediction intervals and the results show that multiple interval prediction scheme shows better performance than the single interval scheme. Performance of the proposed CAC policies indicates their suitability for QoS provisioning for traffic of multimedia connections in future 5G networks

QoS support in satellite and wireless networks : study under the network simulator (NS-2)

Aquest projecte es basa en l'estudi de l'oferiment de qualitat de servei en xarxes wireless i satel·litals. Per això l'estudi de les tècniques de cross-layer i del IEEE 802.11e ha sigut el punt clau per al desenvolupament teòric d'aquest estudi. Usant el simulador de xarxes network simulator, a la part de simulacions es plantegen tres situacions: l'estudi de la xarxa satel·lital, l'estudi del mètode d'accés HCCA i la interconnexió de la xarxa satel·lital amb la wireless. Encara que aquest últim punt, incomplet en aquest projecte, ha de ser la continuació per a futures investigacions.Este proyecto se basa en el estudio del ofrecimiento de calidad de servicio en redes wireless y satelitales. Por eso el estudio de las técnicas de cross-layer y del IEEE 802.11eha sido el punto clave para el desarrollo teórico de este estudio. Usando el simulador de redes network simulator, en la parte de simulaciones se plantean tres situaciones: el estudio de la red satelital, el estudio del método de acceso HCCA y la interconexión de la red satelital con la wireless. Aunque este último punto, incompleto en este proyecto, tiene que ser la continuación para futuras investigaciones.This project is based on the study of offering quality of service in satellite and wireless networks. For that reason the study of the techniques of cross-layer and the IEEE 802.11e has been the key point for the theoretical development of this study. Using the software network simulator, in the part of simulations three situations consider: the study of the satellite network, the study of the access method HCCA and the interconnection of the satellite network with the wireless. Although this last point, incomplete in this work, must be the continuation for future investigations

Minimal Energy Routing for Deep Space Satellite Networks

The purpose of this research is to find out a packet routing algorithm for link error rate aware satellite networks, achieving minimal network energy utilization. The existing energy aware routing protocols typically select routes that minimize the total transmission power over the satellites of the path, but do not consider the retransmissions that may be needed. A new protocol considering the link error rates in route selections for satellite networks is required. In our approach of data routing, the effective total transmissions and the energy required for these transmissions is considered. The simulator developed in C#.NET was designed and programmed to simulate and analyze the proposed link error rate aware routing protocol performance. Satellite network models for the simulation were developed using BRITE, a topology generator framework. Simulations are performed and the algorithm performance is analyzed in terms of energy load balance and schedule lengths.Computer Science Departmen

Satellite Communications

This study is motivated by the need to give the reader a broad view of the developments, key concepts, and technologies related to information society evolution, with a focus on the wireless communications and geoinformation technologies and their role in the environment. Giving perspective, it aims at assisting people active in the industry, the public sector, and Earth science fields as well, by providing a base for their continued work and thinking

Packet scheduling in satellite HSDPA networks.

Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2010.The continuous growth in wireless networks is not showing any sign of slowing down as new services, new technologies and new mobile users continue to emerge. Satellite networks are expected to complement the terrestrial network and be a valid option to provide broadband communications services to both fixed and mobile users in scenarios where terrestrial networks cannot be used due to technical and economical viability. In the current emerging satellite networks, where different users with varying traffic demands ranging from multimedia, voice to data and with limited capacity, Radio Resource Management (RRM) is considered as one of the most significant and challenging aspect needed to provide acceptable quality of service that will meet the requirements of the different mobile users. This dissertation considers Packet Scheduling in the Satellite High Speed Downlink Packet Access (S-HSDPA) network. The main focus of this dissertation is to propose a new cross-layer designed packet scheduling scheme, which is one of the functions of RRM, called Queue Aware Channel Based (QACB) Scheduler. The proposed scheduler, which, attempts to sustain the quality of service requirements of different traffic requests, improves the system performance compared to the existing schedulers. The performance analysis comparison of the throughput, delay and fairness is determined through simulations. These metrics have been chosen they are three major performance indices used in wireless communications. Due to long propagation delay in HSDPA via GEO satellite, there is misalignment between the instantaneous channel condition of the mobile user and the one reported to the base station (Node B) in S-HSDPA. This affects effectiveness of the channel based packet schedulers and leads to either under utilization of resource or loss of packets. Hence, this dissertation investigates the effect of the introduction of a Signal-to-Noise (SNR) Margin which is used to mitigate the effect of the long propagation delay on performance of S-HSDPA, and the appropriate SNR margin to be used to achieve the best performance is determined. This is determined using both a semi-analytical and a simulation approach. The results show that the SNR margin of 1.5 dB produces the best performance. Finally, the dissertation investigates the effect of the different Radio Link Control (RLC) Transmission modes which are Acknowledged Mode (AM) and Unacknowledged Mode (UM) as it affects different traffic types and schedulers in S-HSDPA. Proportional fair (PF) scheduler and our proposed, QACB, scheduler have been considered as the schedulers for this investigation. The results show that traffic types are sensitive to the transmitting RLC modes and that the QACB scheduler provides better performance compared to PF scheduler in the two RLC modes considered

Load balancing in heterogeneous wireless communications networks. Optimized load aware vertical handovers in satellite-terrestrial hybrid networks incorporating IEEE 802.21 media independent handover and cognitive algorithms.

Heterogeneous wireless networking technologies such as satellite, UMTS, WiMax and WLAN are being used to provide network access for both voice and data services. In big cities, the densely populated areas like town centres, shopping centres and train stations may have coverage of multiple wireless networks. Traditional Radio Access Technology (RAT) selection algorithms are mainly based on the ¿Always Best Connected¿ paradigm whereby the mobile nodes are always directed towards the available network which has the strongest and fastest link. Hence a large number of mobile users may be connected to the more common UMTS while the other networks like WiMax and WLAN would be underutilised, thereby creating an unbalanced load across these different wireless networks. This high variation among the load across different co-located networks may cause congestion on overloaded network leading to high call blocking and call dropping probabilities. This can be alleviated by moving mobile users from heavily loaded networks to least loaded networks. This thesis presents a novel framework for load balancing in heterogeneous wireless networks incorporating the IEEE 802.21 Media Independent Handover (MIH). The framework comprises of novel load-aware RAT selection techniques and novel network load balancing mechanism. Three new different load balancing algorithms i.e. baseline, fuzzy and neural-fuzzy algorithms have also been presented in this thesis that are used by the framework for efficient load balancing across the different co-located wireless networks. A simulation model developed in NS2 validates the performance of the proposed load balancing framework. Different attributes like load distribution in all wireless networks, handover latencies, packet drops, throughput at mobile nodes and network utilization have been observed to evaluate the effects of load balancing using different scenarios. The simulation results indicate that with load balancing the performance efficiency improves as the overloaded situation is avoided by load balancing

Space-Based Information Infrastructure Architecture for Broadband Services

This study addressed four tasks: (1) identify satellite-addressable information infrastructure markets; (2) perform network analysis for space-based information infrastructure; (3) develop conceptual architectures; and (4) economic assessment of architectures. The report concludes that satellites will have a major role in the national and global information infrastructure, requiring seamless integration between terrestrial and satellite networks. The proposed LEO, MEO, and GEO satellite systems have satellite characteristics that vary widely. They include delay, delay variations, poorer link quality and beam/satellite handover. The barriers against seamless interoperability between satellite and terrestrial networks are discussed. These barriers are the lack of compatible parameters, standards and protocols, which are presently being evaluated and reduced

Handover and Channel Allocation Mechanisms in Mobile Satellite Networks

In this work we study first handover prediction in non-geostationary mobile satellite networks. The ultimate choice of the transition path depends on UT position and signal strength. We investigate the procedure of beam monitoring and propose UT maximum residence as the criterion for path selection. The UT must operate both in full- and half-duplex mode, the latter being desirable when power limitations are imposed. We propose a scheme that achieves this goal and guarantees efficient diversity provision. Constant delay contours on the earth's surface are defined. The problem of reliable time delay acquisition is addressed, in case synchronization is lost. The SBS solves that either by using the known estimate of UT position or by requesting a measurement report by the UT. The problem of channel allocation appears in cellular networks of every kind. Calls arising in the cell overlap area have access to channels of more than one base station and may choose which base station they will use to establish connection. In that case the problems of base station and channel assignment arise jointly. We address the problem in a linear cellular network and aim at the minimumnumber of utilized channels. We present two algorithms: The first one expands Load Balancing in clique populations and is Sequential Clique Load Balancing (SCLB). The second one is named Clique Load Balancing with Inverse Water-Filling (CLB-IWF). In a dynamic environment, we unify SCLB and CLB-IWF into CLB-DA, which comprises Dynamic Allocation. CLB-DA is compared with Least Loaded Routing (LLR) policy and with Random Routing policy. We finally deduce that at light loads CLB-DA outperforms LLR, attaining smaller blocking probability, whereas at heavier loads all three policies converge