This paper presents a novel Long Term Evolution (LTE) mobile wireless testbed for streaming multimedia Quality of Experience (QoE) experimentation. The software-radio based design of the testbed provides an extremely flexible architecture which offers detailed insights into all elements of the entire LTE network protocol stack from physical to application layer. With the testbed, we aim to bridge the gap between video content providers such as YouTube and commercial LTE operators by identifying and testing viable approaches to enhance end-user quality of experience (QoE). In this work, we focus on the design and implementation of the automated and instrumented testbed, and share results from our initial experiments.

Current wireless research is dominated by the need to satisfy ever-increasing demands for high-speed mobile wireless data. To satisfy these demands, researchers employ flexible, agile software-based radio systems which efficiently use the resources available to them. Dynamic Spectrum Access (DSA) and cognitive radio are key concepts for achieving these research goals. This paper presents Spectrum Wars, a game designed to inform about DSA and cognitive radio but which has also proven to be an effective tool in educating about many of the basic principles of wireless telecommunications. The game pits two teams of players against each other to create and maintain wireless connections in a dynamic environment in order to transfer data as quickly as possible between a transmitter and receiver. Built upon Iris, an open-source framework for software radio, Spectrum Wars is freely available to be recreated, reused, expanded and improved. The paper explains the background of DSA and cognitive radio and gives an overview of the Iris framework. It discusses related work including the MANIAC challenge and the DARPA spectrum challenge before presenting the game itself, examining the feedback of players and exploring the possibilities for future work and improvement.

This paper suggests that the regulatory tool known as the Block Edge Mask (BEM), which is used to define the technical conditions governing a spectrum license, can be used as an instrument to jointly drive spectrum and energy efficiency in a network. The paper explores this concept and goes on to show how networks can generate waveforms which comply with the energy limits of the BEM and at the same time make best use of the spectral resources available to them. The focus of the paper is on orthogonal frequency division multiplexing (OFDM) waveforms. The spectrum- and energy-efficient BEM-compliant waveforms are generated using a process that optimally combines symbol shaping and subcarrier-power loading to create a waveform that minimizes the difference between the transmitted wave and BEM. Practical considerations relating to peak-to-average-power-ratio (PAPR) reduction and time and frequency synchronization issues are explored to ensure the BEM-compliant waveforms can be transmitted with minimal changes to the transceiver. It is envisaged that these techniques will be used by transmitters that change their frequency of operation and in doing so need to shape their transmitted waveforms to comply with the different BEMs governing the use of the different spectrum blocks they wish to access.

The emergence of cognitive radio and software defined networks are signs of a network world that is much more dynamic. These kinds of systems support reconfiguration of the radio or the network to suit user demands and prevailing conditions so that bandwidth and other resources can be directed to where they are needed. As communication systems become ever more sophisticated, achieving high computational capacity while supporting a high level of flexibility becomes more of a challenge. In this paper we focus on the computational complexity and flexibility that will be required of future cognitive radios. The challenge is to achieve sufficient computational capacity, in particular for processing wide-band high-bitrate waveforms, within acceptable size, weight and power consumption limits while supporting significant flexibility. One method of addressing this problem is through the use of hybrid processing architectures that provide both programmability and performance. In particular we focus on a cognitive radio framework called Iris and explore how Xilinx's Zynq system-on-chip (SoC) can deliver the kind of performance that is needed of future cognitive radio systems. The Zynq SoC has the flexibility offered by an ARM based processing system (PS), while also having performance-orientated programmable logic (PL). The challenges of multi-core programming on embedded platforms and the difficulties of accelerating the cognitive radio functionality in the PL are discussed.

We define a cyclostationary signature as a feature which may be intentionally embedded in a digital communications signal, detected through cyclostationary analysis and used as a unique identifier. The purpose of this paper is to demonstrate how cyclostationary signatures can be exploited to overcome a number of the challenges associated with network coordination in emerging cognitive radio applications and spectrum sharing regimes. In particular we show their uses for signal detection, network identification and rendezvous and discuss these in the context of dynamic spectrum access. We present a theoretical discussion followed by application-oriented examples of the cyclostationary signatures used in practical cognitive radio and dynamic spectrum usage scenarios. We focus on orthogonal frequency division multiplexing (OFDM) based systems and present an analysis of a transceiver implementation employing these techniques developed on a cognitive radio test platform.

The Centre for Telecommunications Value-Chain Research (CTVR) and the Center for Wireless Telecommunications (CWT) are undertaking a joint collaborative research project investigating the potential of different software-defined radio (SDR) and cognitive radio (CR) systems that can interoperate and co-exist in common frequency bands.This paper presents some key results from this experience so far, including an over-the-air interoperability analysis of two different SDR architectures in the same frequency band.An initial analysis of actual co-existence experiences involving primary users and secondary opportunistic spectrum users in a common frequency band is also presented.

The ever increasing demands for access to frequency spectrum and more efficient methods of using this spectrum involving multi-carrier techniques are driving the development of reconfigurable and cognitive wireless devices. The potential for, and the need to accommodate the potentially time-varying entropy in these wireless systems presents several design and implementation challenges. However, significant opportunities for innovation extending from the wireless terminal implementation to the business and market models also exist. This paper focuses on the physical (PHY) and medium-access control (MAC) layer issues of these emerging systems, highlighting the following three main contributions: An introduction to reconfigurable multi-carrier code division multiple access (MC-CDMA), an exploration of the use of reconfigurable MC-CDMA and its impact on the design of the physical (PHY) and medium access control (MAC) layers in a cognitive radio context and overview of the practical design and development considerations of this novel system which is being implemented on a real cognitive radio development testbed.