28 resultados para Radio relay systems


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In this chapter the authors discuss the physical insight of the role of wireless communication in RFID systems. In this respect, this chapter gives a brief introduction on the wireless communication model followed by various communication schemes. The chapter also discusses various channel impairments and the statistical modeling of fading channels based on the environment in which the RFID tag and reader may be present. The chapter deals with the fact that the signal attenuations can be dealt with up to some level by using multiple antennas at the reader transmitter and receiver to improve the performance. Thus, this chapter discusses the use of transmit diversity at the reader transmitter to transmit multiple copies of the signal. Following the above, the use of receiver combining techniques are discussed, which shows how the multiple copies of the signal arriving at the reader receiver from the tag are combined to reduce the effects of fading. The chapter then discusses various modulation techniques required to modulate the signal before transmitting over the channel. It then presents a few channel estimation algorithms, according to which, by estimating the channel state information of the channel paths through which transmission takes place, performance of the wireless system can be further increased. Finally, the Antenna selection techniques are presented, which further helps in improving the system performance.


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Foundational to both the operation and legitimation of our traditional media is the idea of representation: in some sense the images of television, the sounds of radio, the narratives of film, and the various public personalities stand in or in place of ourselves. Likewise our contemporary political system function as an elaborate representational system, where regions, "seats", electorates, the nation, and the nationstate are represented by individuals, parties and symbols. Although, there are differences between and among modern nation-states as clearly different political and cultural agendas are at play, the interplay of contemporary media, culture and politics has produced what can be called a 'representational regime' that more or less operates globally, albeit fragmented into national and regional groupings.

This paper explores the initial stages in the breakdown of this system of representation that has allowed a certain organization of culture and politics to expand and develop over the last two centuries. It acknowledges that central to this regime is something Nick Couldry has identified as "the myth of the mediated centre" (Couldry, 2003). What the paper argues, and therefore differs from Couldry's conclusion, is that there are cracks in the glue that holds the system together and they are emerging in the uses of new media. Through an exploration of presentational media - that is, media that is more involved with the presentation of the self for public/private and networked consumption than traditional media's effort to embody their audience in its narratives - the paper reaches for conclusions that identify a more elaborate legitimation crisis looming in our political and cultural worlds.

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Radio Frequency Identification Technology (RFIO) has been explored for various process enhancements in clinical contexts, particularly hospitals, for asset tracking. The technology has been accepted in such environments, as it is inexpensive and, in principle, uncomplicated to integrate with other clinical support systems. It is perceived to offer many benefits to currently resource critical/strained clinical environments. This research investigation focuses on the exploitation of the potential of the technology, to enhance processes in clinical environments. In this paper, the researchers aimed to uncover if the technology, as presently deployed, has been able to achieve its potential and, in particular, if it has been fully integrated into processes in a way that maximises the benefits that were perceived. This research is part of a larger investigation that aims to develop a meta-model for integration of RFIO into processes in a form that will maximise benefits that may be achievable in clinical environments. As the first phase of the investigation, the key learning from a clinical context (hospital), which has deployed RFIO and attempted to integrate it into the processes, to enable better efficiencies, is presented in this paper. The case method has been used as a methodological framework. Two clinical contexts (hospitals) are involved in the larger project, which constitutes two phases. In Phase 1, semi structured interviews were conducted with a selected number of participants involved with the RFIO deployment project, before and after, in clinical context 1 (hereinafter named as CCl). The results were then synthesised drawing a set of key learning, from different viewpoints (implementers and users), as reported in this paper. These results outline a linear conduit for a new proposed implementation (CC2). On completion of the phase II, the researchers aim to construct a meta-model for maximising the potential of RFIO in clinical contexts. This paper is limited to the first phase that aims to draw key learning to inform the linear conduit.

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The 3rd generation partnership project (3GPP) long term evolution (LTE) standard uses single carrier frequency division multiple access (SCFDMA) scheme for the uplink transmissions and orthogonal frequency division multiplexing access (OFDMA) in downlink. SCFDMA uses DFT spreading prior to OFDMA modulation to map the signal from each user to a subset of the available subcarriers i.e., single carrier modulation. The efficiency of a power amplifier is determined by the peak to average power ratio (PAPR) of the modulated signal. In this paper, we analyze the PAPR in 3GPP LTE systems using root raised cosine based filter. Simulation results show that the SCFDMA subcarrier mapping has a significantly lower PAPR compared to OFDMA. Also comparing the three forms of SCFDMA subcarrier mapping, results show that interleave FDMA (IFDMA) subcarrier mapping with proposed root raised cosine filter reduced PAPR significantly than localized FDMA (LFDMA) and distributed (DFDMA) mapping. This improves its radio frequency (RF) power amplifier efficiency and also the mean power output from a battery driven mobile terminal.

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The use of emerging technologies ( such as RFID - Radio Frequency Identification and remote sensing) can be employed to reduce health care costs and also to facilitate the automatic streamlining of infectious disease outbreak detection and monitoring processes in local health departments. It can assist medical practitioners with fast and accurate diagnosis and treatments. In this paper we outline the design and application of a real-time RFID and sensor-base Early Infectious (e.g., cholera) Outbreak Detection and Monitoring (IODM) system for health care.

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Long term evolution (LTE) is the final step toward the 4th generation (4G) of radio technologies designed to increase the capacity and speed of mobile networks. LTE uses orthogonal frequency division multiple access (OFDMA) for the downlink transmission and single carrier-frequency division multiple access (SC-FDMA) for uplink. OFDMA meets the 4G requirement for spectrum flexibility and enables cost-efficient solutions for very wide carriers with high peak rates. However, the potentially large peak-to-average power ratio (PAPR) of the transmitting signals has limited its application. This high PAPR causes interference when the OFDM signals are passed through an amplifier which does not have enough linear range. In this article, we investigate a clipping based PAPR reduction method for LTE OFDMA systems. Simulation results show that the clipping method is reduced PAPR significantly which decreases as the number of clip and filtering level is increased. As a results, increase the mean transmit power, and improve the power amplifier efficiency. This comes at the outlay of complexity, efficiency as well as cost.

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The use of RFID (Radio Frequency Identification) technology can be employed for tracking and detecting each container, pallet, case, and product uniquely in the supply chain. It connects the supply chain stakeholders (i.e.; suppliers, manufacturers, wholesalers/distributors, retailers and customers) and allows them to exchange data and product information. Despite these potential benefits, security issues are the key factor in the deployment of a RFID-enabled system in the global supply chain. This paper proposes a hybrid approach to secure RFID transmission in Supply Chain Management (SCM) systems using modified Wired Equivalent Encryption (WEP) and Rivest, Shamir and Adleman (RSA) cryptosystem. The proposed system also addresses the common loop hole of WEP key algorithm and makes it more secure compare to the existing modified WEP key process.

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The Radio frequency identification (RFID) system is a new technology which uses the open air to transmit information. RFID technology is one of the most promising technologies in the field of ubiquitous computing which is revolutionizing the supply chain. It has already been applied by many major retail chains such as Target, Wal-Mart, etc. The networked RFID system such as supply chain has very unique and special business needs which lead to special sets of RFID security requirements and security models. However, very little work has been done to analyze RFID security parameters in relation to networked RFID systems business needs. This paper presents a critical analysis of the networked application's security requirements in relation to their business needs. It then presents a comparative study of existing literature and the ability of various models to protect the security of the supply chain in a RFID deployment.

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Radio Frequency Identification (RFID) system is anemerging technology for automating object identification. TheNetworked RFID System (NRS) is a component of a distributedobject identification network which facilitates automated supplychain management. It also makes the Internet of Things (IoT)concept a reality. To increase the business feasibility of NRSimplementation, the system should be able to ensure the visibilityand traceability of the object throughout the chain using achecker protocol. By doing so, the protocol will check thegenuineness of the object and the genuineness of the object’sprevious travel path on-site. While doing so, the protocol needs toensure the security requirement of the system. To this end, wepropose a secure checker protocol for NRS which will use a PUF(Physically Unclonable Function) and simple cryptographicprimitives. The protocol provides security (protect privacy of thepartners, injection of fake objects, non-repudiation, andunclonability), visibility and traceability for NRS. It is alsosuitable for passive tags.

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Networked systems have adapted Radio Frequency identification technology (RFID) to automate their business process. The Networked RFID Systems (NRS) has some unique characteristics which raise new privacy and security concerns for organizations and their NRS systems. The businesses are always having new realization of business needs using NRS. One of the most recent business realization of NRS implementation on large scale distributed systems (such as Internet of Things (IoT), supply chain) is to ensure visibility and traceability of the object throughout the chain. However, this requires assurance of security and privacy to ensure lawful business operation. In this paper, we are proposing a secure tracker protocol that will ensure not only visibility and traceability of the object but also genuineness of the object and its travel path on-site. The proposed protocol is using Physically Unclonable Function (PUF), Diffie-Hellman algorithm and simple cryptographic primitives to protect privacy of the partners, injection of fake objects, non-repudiation, and unclonability. The tag only performs a simple mathematical computation (such as combination, PUF and division) that makes the proposed protocol suitable to passive tags. To verify our security claims, we performed experiment on Security Protocol Description Language (SPDL) model of the proposed protocol using automated claim verification tool Scyther. Our experiment not only verified our claims but also helped us to eliminate possible attacks identified by Scyther.

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In space-based networks, the data relay satellites can assist low-earth-orbit satellites in relaying data to other satellites or the ground station and improve the real time system throughput. To take full advantage of transmission resource of the cooperative relays, this paper proposes a multiple access and resource allocation strategy, in which relays can receive and transmit simultaneously according to channel characteristics of space-based systems. Based on the queueing theoretic formulation, the stability of the proposed protocol is analyzed and the maximum stable throughput region is derived, which would provide the appropriate guidance for the design of the system optimal control. Simulation results exhibit multiple factors that affect the stable throughput and verify the theoretical analysis.

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Many algorithms have been introduced to deterministically authenticate Radio Frequency Identification (RFID) tags, while little work has been done to address scalability issue in batch authentications. Deterministic approaches verify tags one by one, and the communication overhead and time cost grow linearly with increasing size of tags. We design a fast and scalable counterfeits estimation scheme, INformative Counting (INC), which achieves sublinear authentication time and communication cost in batch verifications. The key novelty of INC builds on an FM-Sketch variant authentication synopsis that can capture key counting information using only sublinear space. With the help of this well-designed data structure, INC is able to provide authentication results with accurate estimates of the number of counterfeiting tags and genuine tags, while previous batch authentication methods merely provide 0/1 results indicating the existence of counterfeits. We conduct detailed theoretical analysis and extensive experiments to examine this design and the results show that INC significantly outperforms previous work in terms of effectiveness and efficiency.