Collaborative spectrum sensing optimisation algorithms for cognitive radio networks

The main challenge for a cognitive radio is to detect the existence of primary users reliably in order to minimise the interference to licensed communications. Hence, spectrum sensing is a most important requirement of a cognitive radio. However, due to the channel uncertainties, local observations are not reliable and collaboration among users is required. Selection of fusion rule at a common receiver has a direct impact on the overall spectrum sensing performance. In this paper, optimisation of collaborative spectrum sensing in terms of optimum decision fusion is studied for hard and soft decision combining. It is concluded that for optimum fusion, the fusion centre must incorporate signal-to-noise ratio values of cognitive users and the channel conditions. A genetic algorithm-based weighted optimisation strategy is presented for the case of soft decision combining. Numerical results show that the proposed optimised collaborative spectrum sensing schemes give better spectrum sensing performance

Distributed storage manager system for synchronized and scalable AV services across networks

This article has been made available through the Brunel Open Access Publishing Fund - Copyright @ 2011 Hindawi Publishing CorporationThis paper provides an innovative solution, namely, the distributed storage manager that opens a new path for highly interactive and personalized services. The distributed storage manager provides an enhancement to the MHP storage management functionality acting as a value added middleware distributed across the network. The distributed storage manager system provides multiple protocol support for initializing and downloading both streamed and file-based content and provides optimum control mechanisms to organize the storing and retrieval of content that are remained accessible to other multiple heterogeneous devices

Delivery of broadband services to SubSaharan Africa via Nigerian communications satellite

Africa is the least wired continent in the world in terms of robust telecommunications infrastructure and systems to cater for its more than one billion people. African nations are mostly still in the early stages of Information Communications Technology (ICT) development as verified by the relatively low ICT Development Index (IDI) values of all countries in the African region. In developing nations, mobile broadband subscriptions and penetration between 2000-2009 was increasingly more popular than fixed broadband subscriptions. To achieve the goal of universal access, with rapid implementation of ICT infrastructure to complement the sparsely distributed terrestrial networks in the hinterlands and leveraging the adequate submarine cables along the African coastline, African nations and their stakeholders are promoting and implementing Communication Satellite systems, particularly in Nigeria, to help bridge the digital hiatus. This paper examines the effectiveness of communication satellites in delivering broadband-based services

No-reference bitstream-based visual quality impairment detection for high definition H.264/AVC encoded video sequences

Ensuring and maintaining adequate Quality of Experience towards end-users are key objectives for video service providers, not only for increasing customer satisfaction but also as service differentiator. However, in the case of High Definition video streaming over IP-based networks, network impairments such as packet loss can severely degrade the perceived visual quality. Several standard organizations have established a minimum set of performance objectives which should be achieved for obtaining satisfactory quality. Therefore, video service providers should continuously monitor the network and the quality of the received video streams in order to detect visual degradations. Objective video quality metrics enable automatic measurement of perceived quality. Unfortunately, the most reliable metrics require access to both the original and the received video streams which makes them inappropriate for real-time monitoring. In this article, we present a novel no-reference bitstream-based visual quality impairment detector which enables real-time detection of visual degradations caused by network impairments. By only incorporating information extracted from the encoded bitstream, network impairments are classified as visible or invisible to the end-user. Our results show that impairment visibility can be classified with a high accuracy which enables real-time validation of the existing performance objectives

From television to multi-platform: less from more or more for less?

This article examines economic aspects of convergence and of multi-platform expansion in the media sector. Focusing on television broadcasters in the UK, it analyses the recent migration of conventional media towards multi-platform strategies and asks whether digitization is making content delivery more resource–intensive than before or whether it is facilitating greater efficiency. Findings suggest that adaptation to a multi-platform outlook on the part of conventional media requires investment in staffing and re-versioning of content. Funding this, especially in a period of economic downturn, has encouraged a more selective approach towards content, with concomitant implications for diversity. Notwithstanding generally low commercial returns from online activities so far, the potential economic advantages to be had from multi-platform are significant. The experience of UK broadcasters suggests a well-executed ‘360-degree’ approach to commissioning and distribution will increase the value that can be realized from any given universe of content, partly because of extended opportunities for consumption of that content, but also because modes of engagement in a digital multi-platform context allow for an improved audience experience and for better signalling of audience preferences back to suppliers

New communication practices on the radio and in the audiosphere

For the past decade or so, internet radio, podcasts, mobile sound apps, and digital libraries of audio content have enjoyed increasing popularity among researchers and receivers of culture. Radio, similarly to other traditional media, often experiments with the opportunities offered by the new media technologies enabling the emergence of new communicational practices. As a starting point, I consider the contemporary audiosphere, which constitutes the auditory part of the audio-visual culture, and the influence of technological changes on radio communications, artists, and receivers. I attempt to answer the question, what happens at genre fringes? What are the characteristic features of the emerging forms? How, when one is faced with new technology, the multimedia world, and virtual reality, can one reach a reflection on the fiction and non-fiction genres on the radio? The expansive character of new technologies is often the source of inspiration for that which is traditional, thus renewing the object of its study. The inclusion of new phenomena within the widely understood auditoriness has a rescuing nature for traditional forms, and, at the same time, offers new opportunities for creators, and thus an area of research for literary scientists, media scientists and literary critics

On Content-centric Wireless Delivery Networks

The flux of social media and the convenience of mobile connectivity has created a mobile data phenomenon that is expected to overwhelm the mobile cellular networks in the foreseeable future. Despite the advent of 4G/LTE, the growth rate of wireless data has far exceeded the capacity increase of the mobile networks. A fundamentally new design paradigm is required to tackle the ever-growing wireless data challenge. In this article, we investigate the problem of massive content delivery over wireless networks and present a systematic view on content-centric network design and its underlying challenges. Towards this end, we first review some of the recent advancements in Information Centric Networking (ICN) which provides the basis on how media contents can be labeled, distributed, and placed across the networks. We then formulate the content delivery task into a content rate maximization problem over a share wireless channel, which, contrasting the conventional wisdom that attempts to increase the bit-rate of a unicast system, maximizes the content delivery capability with a fixed amount of wireless resources. This conceptually simple change enables us to exploit the "content diversity" and the "network diversity" by leveraging the abundant computation sources (through application-layer encoding, pushing and caching, etc.) within the existing wireless networks. A network architecture that enables wireless network crowdsourcing for content delivery is then described, followed by an exemplary campus wireless network that encompasses the above concepts.Comment: 20 pages, 7 figures,accepted by IEEE Wireless Communications,Sept.201