The relationship between choice of spectrum sensing device and secondary-user intrusion in database-driven cognitive radio systems

As radios in future wireless systems become more flexible and reconfigurable whilst available radio spectrum becomes scarce, the possibility of using TV White Space devices (WSD) as secondary users in the TV Broadcast Bands (without causing harmful interference to licensed incumbents) becomes ever more attractive. Cognitive Radio encompasses a number of technologies which enable adaptive self-programming of systems at different levels to provide more effective use of the increasingly congested radio spectrum. Cognitive Radio has the potential to use spectrum allocated to TV services, which is not actually being used by these services, without causing disruptive interference to licensed users by using channel selection aided by use of appropriate propagation modelling in TV White Spaces.The main purpose of this thesis is to explore the potential of the Cognitive Radio concept to provide additional bandwidth and improved efficiency to help accelerate the development and acceptance of Cognitive Radio technology. Specifically, firstly: three main classes of spectrum sensing techniques (Energy Detection, Matched Filtering and Cyclostationary Feature Detection) have compare in terms of time and spectrum resources consumed, required prior knowledge and complexity, ranking the three classes according to accuracy and performance. Secondly, investigate spectrum occupancy of the UHF TV band in the frequency range from 470 to 862 MHz by undertaking spectrum occupancy measurements in different locations around the Hull area in the UK, using two different receiver devices; a low cost Software-Defined Radio device and a laboratory-quality spectrum analyser. Thirdly, investigate the best propagation model among three propagation models (Extended-Hata, Davidson-Hata and Egli) for use in the TV band, whilst also finding the optimum terrain data resolution to use (1000, 100 or 30 m). it compares modelled results with the previously-mentioned practical measurements and then describe how such models can be integrated into a database-driven tool for Cognitive Radio channel selection within the TV White Space environment. Fourthly, create a flexible simulation system for creating a TV White Space database by using different propagation models. Finally, design a flexible system which uses a combination of Geolocation Database and Spectrum Sensing in the TV band, comparing the performance of two spectrum analysers (Agilent E4407B and Agilent EXA N9010A) with that of a low cost Software-Defined Radio in the real radio environment. The results shows that white space devices can be designed using SDRs based on the Realtek RTL2832U chip (RTL-SDR), combined with a geolocation database for identifying the primary user in the specific location in a cost-effective manner. Furthermore it is shown that improving the sensitivity of RTL-SDR will affect the accuracy and performance of the WSD

Secure Cloud Controlled Software Defined Radio Network For Bandwidth Allocation

The purpose of this research is to investigate the impact of mobility of wireless devices for opportunistic spectrum access and communications using National Instrument Universal Software Radio Peripherals devices. The overall system utilizes software defined radio networks for frequency allocation, cloud connectivity to maintain up-to-date information, and moving target defense as a security mechanism. Each USRP device sends its geolocation to query the spectrum database for idle channels. The cloud cluster was designed for complex data storage and allocation using a smart load balancer to offer ultra-security to users. This project also explores the advantages of data protection and security through moving target defense. To achieve this, the system would use an array of antennas to split the data into different parts and transmit them across separate antennas. This research provides the design to each of the mentioned projects for the implementation of a fully developed system

Improved Resource Allocation for TV White Space Network Based on Modified Firefly Algorithm

There is continued increased demand for dynamic spectrum access of TV White Spaces (TVWS) due to growing need for wireless broadband. Some of the use cases such as cellular (2G/3G/4G/5G) access to TVWS may have a high density of users that want to make use of TVWS. When there is a high density of secondary users (SUs) in a TVWS network, there is possibility of high interference among SUs that exceeds the desired threshold and also harmful interference to primary users (PUs). Optimization of resource allocation (power and spectrum allocation) is therefore necessary so as to protect PUs against harmful interference and to reduce the level of interference among SUs. Existing resource allocation optimization algorithms for a TVWS network ignore adjacent channel interference, interference among SUs or apply greedy algorithms which result in sub-optimal resource allocation. In this paper we propose an improved resource allocation algorithm based on continuous-binary firefly algorithm. Simulation is done using Matlab. Simulation results show that the proposed algorithm improves the SU sum throughput and SU signal to interference noise(SINR) ratio in the secondary network

Malawi's TV white space regulations : a review and comparison with FCC and Ofcom regulations

Regulators are in the process of framing regulations to allow secondary use of vacant TV channels while protecting TV broadcast services from harmful interference. While the US and UK regulators have already passed such regulations in 2008 and 2015 respectively, other countries are still in drafting stages and the underlying circumstances in these countries could be different from those of the US and UK. Malawi released its final draft regulations in 2016. While the US and UK legislate for dynamic spectrum access and licence-exemption for secondary users, Malawi’s draft regulations require such users to apply for a licence for assigned TV white space spectrum. This paper provides an analytical review of Malawi’s regulations and a comparison with FCC and Ofcom regulations, which new regulations can build on. This analysis will also inform future work on network management tools that can enable practical deployment and coexistence of large-scale TV white space networks in a dynamic spectrum access environment in Africa

GEOLOCATION AWARE RESOURCE ALLOCATION IN CELLULAR BASED COGNITIVE RADIO NETWORKS WITH GREEN COMMUNICATION PERSPECTIVE

This paper puts forward a Geolocation aware spectrum and power allocation scheme for cellular-based cognitive radio network using the principle of sensing free spectrum access. The problem formulation to test the feasibility of deploying the secondary system within Terrestrial Trunked Radio (TETRA) based cellular primary system is carried out to maximize the served Secondary Users (SU) while keeping the interference to Primary Users (PU) under a predefined threshold. A novel model called Primary Mobility Contour (PMC) for the avoidance of harmful interference to PU is proposed, which will consider the velocity of PU, the time taken by the secondary base station for transmission and Geolocation information. Using this model sensing free spectrum and power allocation algorithm is developed for cellular-based cognitive radio network to maximize the served SU to enhance system throughput and achieve an enhanced energy efficiency of the system to attain green communication. Simulation results confirm that the proposed scheme maximizes the served SUs per cell, throughput and energy efficiency