This report presents an implementation of the software part in a software definedradio. The radio is not entirely implemented in software and therefore there arecertain limitations on the received signal. The parts implemented are oscillator,decimation filter, carrier synchronization, time synchronization, package detection,and demodulation. Different algorithms were tested for the different partsto measure the power consumption. To understand how the number of bits usedto represent the signal affects the power consumption, the number of bits wasreduced from 20 bits to 10 bits. This reduction reduced the power consumptionfrom 2.57mW to 1.89mW. A small change in the choice of algorithms was thenmade which reduced the power consumption to 1.86mW. Then the clock rate wasreduced for some parts of the system which reduced the power consumption to1.05mW.

Virtualization is becoming more and more popular since the hardware that is available today often has theability to run more than just a single machine. The hardware is too powerful in relation to the requirementsof the software that is supposed to run on the hardware, making it inefficient to run too little software ontoo powerful of machines. With virtualization, the ability exists to run a lot of different software on thesame hardware, thereby increasing the efficiency of hardware usage.Virtualization doesn't stop at just virtualizing operating systems or commodity software, but can also beused to virtualize networking components. These networking components include everything from routersto switches and are possible to set up on any kind of virtulized system.When discussing virtualization of networking components, the experssion “Software Defined Networking”is hard to miss. Software Defined Networking is a definition that contains all of these virtualized networkingcomponents and is the expression that should be used when researching further into this subject. There'san increasing interest in these virtualized networking components now in relation to just a few years ago.This is due to company networking becoming much more complex now in relation to the complexity thatcould be found in a network a few years back. More services need to be up inside of the network and a lotof people believe that Software Defined Networking can help in this regard.This thesis aim is to try to find out what kind of differences there are between multiple different softwarerouters. Finding out things like, which one of the routers that offer the highest network speed for the leastamount of hardware cost, are the kind of things that this thesis will be focused on. It will also look at somedifferent aspects of performance that the routers offer in relation to one another in order to try toestablish if there exists any kind of “best” router in multiple different areas.The idea is to build up a virtualized network that somewhat relates to how a normal network looks insmaller companies today. This network will then be used for different types of testing while having thesoftware based router placed in the middle and having it take care of routing between different local virtualnetworks. All of the routers will be placed on the same server and their configuration will be very basicwhile also making sure that each of the routers get access to the same amount of hardware.After initial testing, all routers that perform bad will be opted out for additional testing. This is done tomake sure that there's no unnecessary testing done on routers that seem to not be able to keep up withthe other ones. The results from these tests will be compared to the results of a hardware router with thesame kind of tests used with it in the middle in relation to the tests the software routers had to go through.The results from the testing were fairly surprising, only having one single router being eliminated early onas the remaining ones continued to “battle” one another with more tests. These tests were compared tothe results of a hardware router and the results here were also quite surprising with a much betterperformance in many different areas from the software routers perspective.

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science in Engineering, 2016 / Data-intensive research computing requires the capability to transfer les over long distances at high throughput. Stateful rewalls introduce su cient packet loss to prevent researchers from fully exploiting high bandwidth-delay network links [25]. To work around this challenge, the science DMZ design [19] trades o stateful packet ltering capability for loss-free forwarding via an ordinary Ethernet switch. We propose a novel extension to the science DMZ design, which uses an SDN-based rewall. This report introduces NFShunt, a rewall based on Linux's Net lter combined with OpenFlow switching. Implemented as an OpenFlow 1.0 controller coupled to Net lter's connection tracking, NFShunt allows the bypass-switching policy to be expressed as part of an iptables rewall rule-set. Our implementation is described in detail, and latency of the control-plane mechanism is reported. TCP throughput and packet loss is shown at various round-trip latencies, with comparisons to pure switching, as well as to a high-end Cisco rewall. Cost, as well as operations and maintenance aspects, are compared and analysed. The results support reported observations regarding rewall introduced packet-loss, and indicate that the SDN design of NFShunt is a technically viable and cost-e ective approach to enhancing a traditional rewall to meet the performance needs of data-intensive researchers / GS2016

A research report submitted to the Faculty of Engineering and the Built Environment of the University of the Witwatersrand in partial fulfilment of the requirements for the degree of Master of Science in Engineering February 2017 / Software-defined networking (SDN) is the physical separation of the control and data planes in networking devices. A logically centralised controller plane which uses a network-wide view data structure to control several data plane devices is another defining attribute of SDN. The centralised controllers and the network-wide view data structure are difficult to scale as the network and the data it carries grow. Solutions which have been proposed to combat this challenge in SDN lack the use of the statistical properties of the workload or network traffic seen by SDN controllers. Hence, the objective of this research is twofold: Firstly, the statistical properties of the controller workload are investigated. Secondly, Autoregressive Integrated Moving Average Models (ARIMA) and Artificial Neural Network (ANN) models are investigated to establish the feasibility of forecasting the controller workload signal. Representations of the state of the controller plane in the network-wide view in the form of forecasts of the controller workload will enable control applications to detect dwindling controller resources and therefore alleviate controller congestion. On the other hand, realistic statistical traffic models of the controller workload variable are sought for the design and evaluation of SDN controllers. A data center network prototype is created by making use of an SDN network emulator called Mininet and an SDN controller called Onos. It was found that 1–2% of flows arrive within 10 s of each other and more than 80% have inter-arrival times in the range of 10 s–10ms. These inter-arrival times were found to follow a beta distribution, which is similar to findings made in Machine Type Communications (MTC). The use of ARIMA and ANN to forecast the controller workload established that it is feasible to forecast the workload seen by SDN controllers. The accuracy of these models was found to be comparable for continuously valued time series signals. The ANN model was found to be applicable even in discretely valued time series data. / MT2017

The introduction of software radio has meant that standards for radio communication can evolve in a much more natural way, changing only a little at a time without making all of the hardware obsolete. It has become apparent that these changes may affect some systems more favourably than others so allowing the software radio to decide how to adapt can actually improve the link quality. This development is known as cognitive radio and can improve the performance of a single radio link. As an extension of this progress is being made on designing cognitive networks where the software radios which make up the network not only optimise their own link but share information about their goals and situation with other nodes in the network, using all of this data together can optimise overall end-to-end performance of the network. These advances in network design and optimisation come at a time where many parts of the world are re-structuring the television broadcast bands. These have been allocated for a long time and are a generous allocation of a valuable resource. With the power of a cognitive network it is possible to design equipment that can automatically avoid the licensed TV transmitters which only take a fraction of the total bandwidth in any one area. This allows many smaller cells to be fitted between the main transmitters. Assessing the availability of bandwidth and generating maps of available spectrum for these new cognitive networks requires a new approach to radio propagation modelling in the TV bands. Previous models use a worst case scenario to make sure that there is at least enough signal to receive the public service broadcasts in the majority of homes. Predicting where the limits of reception are and where it would be safe to broadcast on these channels requires a better, terrain dependent transmission model. In this thesis the Parabolic Equation Model is applied to the problem of predicting TV band occupancy and the results of this modelling is compared to field measurement to get an idea of how accurate the model is in practice.

"A comprehensive analysis of a novel detection scheme for SISO wireless transmission scenarios is presented in this dissertation. The scheme, which is based on Belief-Propagation (BP) detectors, is evaluated in both a computer simulation environment and a custom-built software-defined radio test-bed. In this dissertation, we address the design aspects of BP-based receivers, including several approaches to minimize the bit error rate of MAP detectors. We also present the development of an interface framework for a software defined radio platform that aims to implement complex communication transceivers capable of prototyping the hybrid structure with a pre-filter filter and BP detector. Numerical simulations compared the proposed schemes with an existing approaches and showed significant performance gains without requiring great computational cost at the receiver. Furthermore, experiments using GNU Radio Companion and the FMCOMMS software defined radio hardware platform confirm the correct functionality of the proposed interface, and stress tests are conducted to assess the functionality of the interface and how it deteriorates across a range of operating conditions. Finally, we present several experiments using the FMCOMMS software defined radio platform that implement the proposed BP-based receiver scheme and discuss its capabilities and limitations."

In enterprise networks, all aspects of the network, such as placement of security devices and performance, must be carefully considered. Even with forethought, networks operators are ultimately unaware of intra-subnet traffic. The inability to monitor intra-subnet traffic leads to blind spots in the network where compromised hosts have unfettered access to the network for spreading and reconnaissance. While network security middleboxes help to address compromises, they are limited in only seeing a subset of all network traffic that traverses routed infrastructure, which is where middleboxes are frequently deployed. Furthermore, traditional middleboxes are inherently limited to network-level information when making security decisions. Software-defined networking (SDN) is a networking paradigm that allows logically centralized control of network switches and routers. SDN can help address visibility concerns while providing the benefits of a centralized network control platform, but traditional switch-based SDN leads to concerns of scalability and is ultimately limited in that only network-level information is available to the controller. This dissertation addresses these SDN limitations in the enterprise by pushing the SDN functionality to the end-hosts. In doing so, we address scalability concerns and provide network operators with better situational awareness by incorporating system-level and graphical user interface (GUI) context into network information handled by the controller. By incorporating host-context, our approach shows a modest 16% reduction in flows that can be processed each second compared to switch-based SDN. In comparison to enterprise networks, residential networks are much more constrained. Residential networks are limited in that the operators typically lack the experience necessary to properly secure the network. As a result, devices on home networks are sometimes compromised and, unbeknownst to the home user, perform nefarious acts such as distributed denial of services (DDoS) attacks on the Internet. Even with operator expertise in residential networks, the network infrastructure is limited to a resource-constrained router that is not extensible. Fortunately, SDN has the potential to increase security and network control in residential networks by outsourcing functionality to the cloud where third-party experts can provide proper support. In residential networks, this dissertation uses SDN along with cloud-based resources to introduce enterprise-grade network security solutions where previously infeasible. As part of our residential efforts, we build and evaluate device-agnostic security solutions that are able to better protect the increasing number of Internet of Things (IoT) devices. Our work also shows that the performance of outsourcing residential network control to the cloud is feasible for up to 90% of home networks in the United States.

"As the demand for bandwidth increases, the inefficient use of the spectrum becomes more apparent and limiting. Currently, secondary (unlicensed) users can not use sparsely occupied portions of radio spectrum that are not allocated to them. In prior research, a variant of Orthogonal Frequency Division Multiplex (OFDM) called Non-Contiguous OFDM (NC-OFDM) was found to be a suitable transmission technique for enabling Dynamic Spectrum Access, which allows for multiple secondary users to share the spectrum. This thesis presents an algorithm for the synchronization of NC-OFDM. Moreover, a hardware architecture is proposed for the synchronization, and a pruned FFT/IFFT core is designed. At present, there has been minimal research into synchronization for NC-OFDM systems. As with any modulation scheme, synchronization is an important part for receiving the transmission successfully. The current synchronization scheme is simulated in variety of wireless channels to show that it can successfully communicate in the tested channels. Additionally a hardware architecture is laid out for the practical implementation of the synchronization algorithm. Since NC-OFDM does not use all of the carriers for transmission, the FFT and IFFT can have their computations reduced. Since the FFT and IFFT are important parts to the receiver and the transmitter, a pruned FFT/IFFT in hardware makes the most sense to be able to reduced the computation. The number of butterfly computations is reduced at the expense of a large increase in resource usage. "

In this thesis, three key issues that restrict networks from scaling up so as to be able to cope with the rapid increase in traffic are investigated and series of approaches are proposed and tested for overcoming them. Firstly, scalability limitations owing to the use of a broadcast mechanism in one collision domain are discussed. To address this matter, servers under software-defined network architectures for eliminating discovery messages (SSED) are designed in this thesis and a backbone of floodless packets in an SDN LAN network is introduced. SSED has an innovative mechanism for defining the relationship between the servers and SDN architecture. Experimental results, after constructing and applying an authentic testbed, verify that SSED has the ability to improve upon the scalability of the traditional mechanism in terms of the number of switches and hosts. This is achieved by removing broadcast packets from the data and control planes as well as offering a better response time. Secondly, the scalability restrictions from using routers and the default gateway mechanism are explained. In this thesis, multiple distributed subnets using SDN architecture and servers to eliminate router devices and the default gateway mechanism (MSSERD) are introduced, designed and implemented as the general backbone for scalable multiple LAN-based networks. MSSERD's proposed components handle address resolution protocol (ARP) discovery packets and general IP packets across different subnets. Moreover, a general view of the network is provided through a multi-subnets discovery protocol (MDP). A 23 computers testbed is built and the results verify that MSSERD scales up the number of subnets more than traditional approaches, enhances the efficiency significantly, especially with high load, improves performance 2.3 times over legacy mechanisms and substantially reduces complexity. Finally, most of the available distributed-based architectures for different domains are reviewed and the aggregation discovery mechanism analysed to establish their impact on network scalability. Subsequently, a general distributed-centralised architecture with open-level control plane (OLC) architecture and a dynamic discovery hierarchical protocol (DHP) is introduced to provide better scalability in an SDN network. OLC can scale up the network with high performance even during high traffic.

As computer networks evolve, they become more complex, introducing several challenges in the areas of performance and management. Such problems can lead to stagnation in network innovation. Software Defined Networks (SDN) framework could be one of the best candidates for improving and revolutionising networking by giving the full control to the network administrators to implement new management and performance optimisation techniques. This thesis examines performance issues faced in SDN due to the introduction of the SDN Controller. These issues include the extra delay due to the round-trip time between the switch and the controller as well as the fact that some packets arrive at the destination out-of-order. We propose a novel dynamic flow installation and management algorithm (OFPE) using the SDN protocol OpenFlow, which preserves the controller to a non-overloaded CPU state and allow it to dynamically add and adjust flow table rules to reduce packet delay and out-of-order packets. In addition, we propose OFPEX, an extension to OFPE algorithm that includes techniques for managing multi-switch environments as well as methods that make use of the packets interarrival time in categorising and serving packet flows. Such techniques allow topology awareness, helping the controller to install flow table rules in such a way to form optimal routes for high priority flows thus increasing network performance. For the performance evaluation of the proposed algorithms, both hardware testbed as well as emulation experiments have been conducted. The performance results indicate that OFPE algorithm achieves a significant enhancement in performance in the form of reduced delay by up to 92.56% (depending on the scenario), reduced packet loss by up to 55.32% and reduced out-of-order packets by up to 69.44%. Furthermore, we propose a novel placement algorithm for distributed Mininet implementations which uses weights in order to distribute the experiment components to the appropriately distributed machines. The proposed algorithm uses static code analysis in order to examine the experimental code as well as it measures the capabilities of physical components in order to create a weights table which is then used to distribute the experiment components properly. The performance results of the proposed algorithm evaluation indicated reductions in delay and packet loss of up to 65.51% and 86.35% respectively, as well as a decrease in the standard deviation of CPU usage by up to 88.63%. These results indicate that the proposed algorithm distributes the experiment components evenly across the available resources. Finally, we propose a series of Benchmarking tests that can be used to rate all the available SDN experimental platforms. These tests allow the selection of the appropriate experimental platform according to the scenario needs as well as they indicate the resources needed by each platform.