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Interference Suppression in Bandwidth Hopping Spread Spectrum Communications
Get PDFBandwidth hopping spread spectrum (BHSS) has recently been proposed as a spectrum-efficient technique to combat jamming. In BHSS, the transmitter is randomly hopping the signal bandwidth in order to make it unpredictable to an attacker. When the signal bandwidth is unpredictable, the attacker cannot match its interference bandwidth to the signal bandwidth of the transmitter, and the receiver can filter out the interference power (or parts of it) prior
demodulation, and thus increase decoding performance. The main challenge in BHSS is that the bandwidth must be hopping very rapidly at the symbol level in order to prevent a reactive jammer from following the hopping pattern by simple tracking techniques. Existing receiver filtering techniques as proposed in prior work require a long time to estimate the filter parameters and are thus
unable to suppress the interference from the jammer when the bandwidth is hopping at the symbol level. In this paper, we propose a new filtering approach adapted for BHSS which is able to suppress arbitrary jamming interference even when the signal bandwidth is hopping after every symbol. Our approach is based on a filter bank which applies different filters in parallel and dynamically selects the best filter for every symbol according to the soft-state output of the demodulator. We evaluate the improvement of our method over classical filtering techniques in experiments using software-defined radios. Our results show a gain in interference suppression above 30 dB with respect to state-of-the-art solutions. We further implement frequency hopping for a BHSS system, and demonstrate the superiority of a system combining hopping in bandwidth, code and frequency against jamming attacks.TRUEpu
Studying TLS Usage in Android Apps
No full textFirst standardized by the IETF in the 1990's, SSL/TLS is the most widely-used encryption protocol on the Internet. This makes it imperative to study its usage across different platforms and applications to ensure proper usage and robustness against attacks and vulnerabilities. While previous efforts have focused on the usage of TLS in the desktop ecosystem, there have been no studies of TLS usage by mobile apps at scale. In our study, we use anonymized data collected by the Lumen mobile measurement app to analyze TLS usage by Android apps in the wild. We analyze and fingerprint handshake messages to characterize the TLS APIs and libraries that apps use, and evaluate their weaknesses. We find that 84% of apps use the default TLS libraries provided by the operating system, and the remaining apps use other TLS libraries for various reasons such as using TLS extensions and features that are not supported by the Android TLS libraries, some of which are also not standardized by the IETF. Our analysis reveals the strengths and weaknesses of each approach, demonstrating that the path to improving TLS security in the mobile platform is not straightforward.
Based on work published at: Abbas Razaghpanah, Arian Akhavan Niaki, Narseo Vallina-Rodriguez, Srikanth Sundaresan, Johanna Amann, and Phillipa Gill. 2017. Studying TLS Usage in Android Apps. In Proceedings of CoNEXT ’17. ACM, New York, NY, USA, 13 pages. https://doi.org/10.1145/3143361.3143400TRUEpu
Modeling resource allocation in cellular networks
No full textAfter cellular network resources are used for a service, they remain allocated to the end user for some time before release, so that if a new service request is generated by the same user, they are immediately available, with no risk of blocking. This behavior differs from the one captured by normal queuing models (for example an M/M/K/0 queue), but it can nevertheless be described with simple networks of queues that yield a closed form expression for the blocking probability. This talk discusses the model development and solution, and compares the model performance predictions to traditional queueing models results, such as the Erlang B formula iteratively applied to the resources that are not blocked by potentially returning users.FALSEpu
The Vertical Slicer: Verticals’ Entry Point to 5G Networks
Get PDFNetwork slicing is the emerging framework for the support of services offered by vertical industries in 5G networks. In order to ensure that the service characteristics required by a vertical are met, it is of paramount importance to adequately interpret the vertical’s requirements and map them onto specifications that the system orchestrator can use to deploy the service. In this paper, we take this challenge and present a new entity, called Vertical Slicer, to be incorporated within the OSS/BSS of 5G networks. We describe the architecture of the Vertical Slicer, as well as its main functional blocks and the algorithms therein.TRUEpu
Unsupervised Scalable Statistical Method for Identifying Influential Users in Online Social Networks
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Arbitration Among Vertical Services
No full textA 5G network provides several service types, tailored to specific needs such as high bandwidth or low latency. On top of these communication services, verticals are enabled to deploy their own vertical services. These vertical service instances compete for the resources of the underlying common infrastructure. We present a resource arbitration approach that allows to handle such resource conflicts on a high level and to provide guidance to lower-level orchestration components.TRUEpu