13,615 research outputs found
Wi-Fi Teeter-Totter: Overclocking OFDM for Internet of Things
The conventional high-speed Wi-Fi has recently become a contender for
low-power Internet-of-Things (IoT) communications. OFDM continues its adoption
in the new IoT Wi-Fi standard due to its spectrum efficiency that can support
the demand of massive IoT connectivity. While the IoT Wi-Fi standard offers
many new features to improve power and spectrum efficiency, the basic physical
layer (PHY) structure of transceiver design still conforms to its conventional
design rationale where access points (AP) and clients employ the same OFDM PHY.
In this paper, we argue that current Wi-Fi PHY design does not take full
advantage of the inherent asymmetry between AP and IoT. To fill the gap, we
propose an asymmetric design where IoT devices transmit uplink packets using
the lowest power while pushing all the decoding burdens to the AP side. Such a
design utilizes the sufficient power and computational resources at AP to trade
for the transmission (TX) power of IoT devices. The core technique enabling
this asymmetric design is that the AP takes full power of its high clock rate
to boost the decoding ability. We provide an implementation of our design and
show that it can reduce the IoT's TX power by boosting the decoding capability
at the receivers
Advancing the Standards for Unmanned Air System Communications, Navigation and Surveillance
Under NASA program NNA16BD84C, new architectures were identified and developed for supporting reliable and secure Communications, Navigation and Surveillance (CNS) needs for Unmanned Air Systems (UAS) operating in both controlled and uncontrolled airspace. An analysis of architectures for the two categories of airspace and an implementation technology readiness analysis were performed. These studies produced NASA reports that have been made available in the public domain and have been briefed in previous conferences. We now consider how the products of the study are influencing emerging directions in the aviation standards communities. The International Civil Aviation Organization (ICAO) Communications Panel (CP), Working Group I (WG-I) is currently developing a communications network architecture known as the Aeronautical Telecommunications Network with Internet Protocol Services (ATN/IPS). The target use case for this service is secure and reliable Air Traffic Management (ATM) for manned aircraft operating in controlled airspace. However, the work is more and more also considering the emerging class of airspace users known as Remotely Piloted Aircraft Systems (RPAS), which refers to certain UAS classes. In addition, two Special Committees (SCs) in the Radio Technical Commission for Aeronautics (RTCA) are developing Minimum Aviation System Performance Standards (MASPS) and Minimum Operational Performance Standards (MOPS) for UAS. RTCA SC-223 is investigating an Internet Protocol Suite (IPS) and AeroMACS aviation data link for interoperable (INTEROP) UAS communications. Meanwhile, RTCA SC-228 is working to develop Detect And Avoid (DAA) equipment and a Command and Control (C2) Data Link MOPS establishing LBand and C-Band solutions. These RTCA Special Committees along with ICAO CP WG/I are therefore overlapping in terms of the Communication, Navigation and Surveillance (CNS) alternatives they are seeking to provide for an integrated manned- and unmanned air traffic management service as well as remote pilot command and control. This paper presents UAS CNS architecture concepts developed under the NASA program that apply to all three of the aforementioned committees. It discusses the similarities and differences in the problem spaces under consideration in each committee, and considers the application of a common set of CNS alternatives that can be widely applied. As the works of these committees progress, it is clear that the overlap will need to be addressed to ensure a consistent and safe framework for worldwide aviation. In this study, we discuss similarities and differences in the various operational models and show how the CNS architectures developed under the NASA program apply
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
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Adaptive authentication and key agreement mechanism for future cellular systems
Since the radio medium can be accessed by anyone, authentication of users is a very important element of a mobile network. Nowadays, in GSM/GPRS a challenge response protocol is used to authenticate the user to the mobile network. Similarly, in third generation mobile systems [3] a challenge response protocol was chosen in such a way as to achieve maximum compatibility with the current GSM security architecture. Both authentication mechanisms use symmetric key cryptography because of the limited processing power of the mobile devices. However, recent research [6] has shown that asymmetric, or public, key cryptography can be enabled successfully in future mobile terminals. In this paper, we propose a new adaptive authentication and key agreement protocol (AAKA) for future mobile communication systems. The novelty of AAKA and its main advantage over other challenge response protocols is that can be adaptive to the mobile environment and use symmetric and/or public key cryptography for user and network authentication
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