Cross-Layer Platform for Dynamic, Energy-Efficient Optical Networks

The design of the next-generation Internet infrastructure is driven by the need to sustain the massive growth in bandwidth demands. Novel, energy-efficient, optical networking technologies and architectures are required to effectively meet the stringent performance requirements with low cost and ultrahigh energy efficiencies. In this thesis, a cross-layer communications platform is proposed to enable greater intelligence and functionality on the physical layer. Providing the optical layer with advanced networking capabilities will facilitate the dynamic management and optimization of optical switching based on performance monitoring measurements and higher-layer attributes. The cross-layer platform aims to create a new framework for networks to incorporate packet-scale measurement subsystems and techniques for monitoring the health of the optical channel. This will allow for quality-of-service- and energy-aware routing schemes, as well as an enhanced awareness of the optical data signals. This thesis first presents the design and development of an optical packet switching fabric. Leveraging a networking test-bed environment to validate networking hypotheses, advanced switching functionalities are demonstrated, including the support for quality-of-service based routing and packet multicasting. The investigated cross-layering is based on emerging optical technologies, enabling packet protection techniques and packet-rate switching fabric reconfiguration. Coupled with fast performance monitoring, the platform will achieve significant performance gains within the endeavor of all-optical switching. Allowing for a more intelligent, programmable optical layer aims to support greater flexibility with respect to bandwidth allocation and potentially a significant reduction in the network's energy consumption. The ultimate deliverable of this work is a high-performance, cross-layer enabled optical network node. The experimental demonstration of an initial prototype creates a dynamic network element with distributed control plane management, featuring fast packet-rate optical switching capabilities and embedded physical-layer performance monitoring modules. The cross-layer box enables an intelligent traffic delivery system that can dynamically manipulate optical switching on a packet-granular scale. With the goal of achieving advanced multi-layer routing and control algorithms, the network node requires an intelligent co-optimization across all the layers. The proposed cross-layer design should drive optical technologies and architectures in an innovative way, in order to fulfill the void between the design of basic photonic devices and the networking protocols that use them. The performance of the entire network -- from the optical components, to the routing algorithms and user applications -- should be optimized in concert. This contribution to the area of cross-layer network design creates an adaptable optical pipe that is extremely flexible and intelligent aware of both the physical optical signals and higher-layer requirements. The impact of this work will be seen in the realization of dynamic, energy-efficient optical communication links in future networking infrastructures

All Optical Signal Processing Technologies in Optical Fiber Communication

Due to continued growth of internet at starling rate and the introduction of new broadband services, such as cloud computing, IPTV and high-definition media streaming, there is a requirement for flexible bandwidth infrastructure that supports mobility of data at peta-scale. Elastic networking based on gridless spectrum technology is evolving as a favorable solution for the flexible optical networking supportive next generation traffic requirements. Recently, research is centered on a more elastic spectrum provision methodology than the traditional ITU-T grid. The main issue is the requirement for a transmission connect, capable of accommodating and handling a variety of signals with distinct modulation format, baud rate and spectral occupancy. Segmented use of the spectrum could lead to the shortage of availableness of sufficiently extensive spectrum spaces for high bitrate channels, resulting in wavelength contention. On-demand space assignment creates not only deviation from the ideal course but also have spectrum fragmentation, which reduces spectrum resource utilization. This chapter reviewed the recent research development of feasible solutions for the efficient transport of heterogeneous traffic by enhancing the flexibility of the optical layer for performing allocation of network resources as well as implementation of optical node by all optical signal processing in optical fiber communication

A scalable packetised radio astronomy imager

Includes bibliographical referencesModern radio astronomy telescopes the world over require digital back-ends. The complexity of these systems depends on many site-specific factors, including the number of antennas, beams and frequency channels and the bandwidth to be processed. With the increasing popularity for ever larger interferometric arrays, the processing requirements for these back-ends have increased significantly. While the techniques for building these back-ends are well understood, every installation typically still takes many years to develop as the instruments use highly specialised, custom hardware in order to cope with the demanding engineering requirements. Modern technology has enabled reprogrammable FPGA-based processing boards, together with packet-based switching techniques, to perform all the digital signal processing requirements of a modern radio telescope array. The various instruments used by radio telescopes are functionally very different, but the component operations remain remarkably similar and many share core functionalities. Generic processing platforms are thus able to share signal processing libraries and can acquire different personalities to perform different functions simply by reprogramming them and rerouting the data appropriately. Furthermore, Ethernet-based packet-switched networks are highly flexible and scalable, enabling the same instrument design to be scaled to larger installations simply by adding additional processing nodes and larger network switches. The ability of a packetised network to transfer data to arbitrary processing nodes, along with these nodes' reconfigurability, allows for unrestrained partitioning of designs and resource allocation. This thesis describes the design and construction of the first working radio astronomy imaging instrument hosted on Ethernet-interconnected re- programmable FPGA hardware. I attempt to establish an optimal packetised architecture for the most popular instruments with particular attention to the core array functions of correlation and beamforming. Emphasis is placed on requirements for South Africa's MeerKAT array. A demonstration system is constructed and deployed on the KAT-7 array, MeerKAT's prototype. This research promises reduced instrument development time, lower costs, improved reliability and closer collaboration between telescope design teams

Design and analysis of a scalable terabit multicast packet switch : architecture and scheduling algorithms

Internet growth and success not only open a primary route of information exchange for millions of people around the world, but also create unprecedented demand for core network capacity. Existing switches/routers, due to the bottleneck from either switch architecture or arbitration complexity, can reach a capacity on the order of gigabits per second, but few of them are scalable to large capacity of terabits per second. In this dissertation, we propose three novel switch architectures with cooperated scheduling algorithms to design a terabit backbone switch/router which is able to deliver large capacity, multicasting, and high performance along with Quality of Service (QoS). Our switch designs benefit from unique features of modular switch architecture and distributed resource allocation scheme. Switch I is a unique and modular design characterized by input and output link sharing. Link sharing resolves output contention and eliminates speedup requirement for central switch fabric. Hence, the switch architecture is scalable to any large size. We propose a distributed round robin (RR) scheduling algorithm which provides fairness and has very low arbitration complexity. Switch I can achieve good performance under uniform traffic. However, Switch I does not perform well for non-uniform traffic. Switch II, as a modified switch design, employs link sharing as well as a token ring to pursue a solution to overcome the drawback of Switch 1. We propose a round robin prioritized link reservation (RR+POLR) algorithm which results in an improved performance especially under non-uniform traffic. However, RR+POLR algorithm is not flexible enough to adapt to the input traffic. In Switch II, the link reservation rate has a great impact on switch performance. Finally, Switch III is proposed as an enhanced switch design using link sharing and dual round robin rings. Packet forwarding is based on link reservation. We propose a queue occupancy based dynamic link reservation (QOBDLR) algorithm which can adapt to the input traffic to provide a fast and fair link resource allocation. QOBDLR algorithm is a distributed resource allocation scheme in the sense that dynamic link reservation is carried out according to local available information. Arbitration complexity is very low. Compared to the output queued (OQ) switch which is known to offer the best performance under any traffic pattern, Switch III not only achieves performance as good as the OQ switch, but also overcomes speedup problem which seriously limits the OQ switch to be a scalable switch design. Hence, Switch III would be a good choice for high performance, scalable, large-capacity core switches

Optically-Connected Memory: Architectures and Experimental Characterizations

Growing demands on future data centers and high-performance computing systems are driving the development of processor-memory interconnects with greater performance and flexibility than can be provided by existing electronic interconnects. A redesign of the systems' memory devices and architectures will be essential to enabling high-bandwidth, low-latency, resilient, energy-efficient memory systems that can meet the challenges of exascale systems and beyond. By leveraging an optics-based approach, this thesis presents the design and implementation of an optically-connected memory system that exploits both the bandwidth density and distance-independent energy dissipation of photonic transceivers, in combination with the flexibility and scalability offered by optical networks. By replacing the electronic memory bus with an optical interconnection network, novel memory architectures can be created that are otherwise infeasible. With remote optically-connected memory nodes accessible to processors as if they are local, programming models can be designed to utilize and efficiently share greater amounts of data. Processors that would otherwise be idle, being starved for data while waiting for scarce memory resources, can instead operate at high utilizations, leading to drastic improvements in the overall system performance. This work presents a prototype optically-connected memory module and a custom processor-based optical-network-aware memory controller that communicate transparently and all-optically across an optical interconnection network. The memory modules and controller are optimized to facilitate memory accesses across the optical network using a packet-switched, circuit-switched, or hybrid packet-and-circuit-switched approach. The novel memory controller is experimentally demonstrated to be compatible with existing processor-memory access protocols, with the memory controller acting as the optics-computing interface to render the optical network transparent. Additionally, the flexibility of the optical network enables additional performance benefits including increased memory bandwidth through optical multicasting. This optically-connected architecture can further enable more resilient memory system realizations by expanding on current error dectection and correction memory protocols. The integration of optics with memory technology constitutes a critical step for both optics and computing. The scalability challenges facing main memory systems today, especially concerning bandwidth and power consumption, complement well with the strengths of optical communications-based systems. Additionally, ongoing efforts focused on developing low-cost optical components and subsystems that are suitable for computing environments may benefit from the high-volume memory market. This work therefore takes the first step in merging the areas of optics and memory, developing the necessary architectures and protocols to interface the two technologies, and demonstrating potential benefits while identifying areas for future work. Future computing systems will undoubtedly benefit from this work through the deployment of high-performance, flexible, energy-efficient optically-connected memory architectures

Analysis and implementation of the Large Scale Video-on-Demand System

Next Generation Network (NGN) provides multimedia services over broadband based networks, which supports high definition TV (HDTV), and DVD quality video-on-demand content. The video services are thus seen as merging mainly three areas such as computing, communication, and broadcasting. It has numerous advantages and more exploration for the large-scale deployment of video-on-demand system is still needed. This is due to its economic and design constraints. It's need significant initial investments for full service provision. This paper presents different estimation for the different topologies and it require efficient planning for a VOD system network. The methodology investigates the network bandwidth requirements of a VOD system based on centralized servers, and distributed local proxies. Network traffic models are developed to evaluate the VOD system's operational bandwidth requirements for these two network architectures. This paper present an efficient estimation of the of the bandwidth requirement for the different architectures.Comment: 9 pages, 8 figure

Neural networks-on-chip for hybrid bio-electronic systems

PhD ThesisBy modelling the brains computation we can further our understanding of its function and develop novel treatments for neurological disorders. The brain is incredibly powerful and energy e cient, but its computation does not t well with the traditional computer architecture developed over the previous 70 years. Therefore, there is growing research focus in developing alternative computing technologies to enhance our neural modelling capability, with the expectation that the technology in itself will also bene t from increased awareness of neural computational paradigms. This thesis focuses upon developing a methodology to study the design of neural computing systems, with an emphasis on studying systems suitable for biomedical experiments. The methodology allows for the design to be optimized according to the application. For example, di erent case studies highlight how to reduce energy consumption, reduce silicon area, or to increase network throughput. High performance processing cores are presented for both Hodgkin-Huxley and Izhikevich neurons incorporating novel design features. Further, a complete energy/area model for a neural-network-on-chip is derived, which is used in two exemplar case-studies: a cortical neural circuit to benchmark typical system performance, illustrating how a 65,000 neuron network could be processed in real-time within a 100mW power budget; and a scalable highperformance processing platform for a cerebellar neural prosthesis. From these case-studies, the contribution of network granularity towards optimal neural-network-on-chip performance is explored