Fast deployable and reliable mission-critical communication networks are fundamental requirements to guarantee the successful operations of public safety officers during disaster recovery and crisis management preparedness. The ABSOLUTE project focused on designing, prototyping and demonstrating a high-capacity IP mobile data network with low latency and large coverage suitable for many forms of multimedia delivery including public safety scenarios. The ABSOLUTE project combines aerial, terrestrial and satellites communication networks for providing an robust standalone system able to delivering resilience communication systems. This article focuses on describing the main outcomes of the ABSOLUTE project in terms of network and system architecture, regulations and implementation of the Aerial Base Stations, Portable Land Mobile Units, Satellite Backhauling, S-MIM Satellite Messaging and Multimode User Equipment.
This paper introduces a rapidly deployable wireless network based on Low Altitude Platforms and portable land units to support disaster-relief activities, and to extend capacity during temporary mass events. The system integrates an amalgam of radio technologies such as LTE, WLAN and TETRA to provide heterogeneous communications in the deployment location. Cognitive radio is used for autonomous network configuration. Sensor networks monitor the environment in real-time during relief activities and provide distributed spectrum sensing capacities. Finally, remote communications are supported via S-band satellite links.
Within this paper we examine a non-geostationary satellite constellation network with inter-satellite links (ISLs) for global air traffic control (ATC) and air passenger communication (APC). More specifically, an analysis is done to investigate the impacts of different routing policies on the end-to-end delay, and a general model describing the delays is developed. All considerations are based on a Galileo-like satellite constellation network and real global flight data of all commercial flights during one day
RObust Header Compression (ROHC) has been successfully included in some wireless standards in order to reduce the excessive IP overhead for small packets, for instance Voice over IP frames. So far, there is limited understanding on how the ROHC performance depends on the design parameters and the characteristics of the wireless channel. In this paper we propose an analytical model that provides simple expressions for the probability of losing synchronization as a function of the mentioned parameters, and also yields insightful relationships between the design variables and the desired system performance. The results are validated against sophisticated and realistic models of ROHC. I. INTRODUCTIONThe importance of ROHC for wireless systems is undisputed [1] [6], since it enables to compress many IP headers by over an order of magnitude with respect to their original size. Such scheme can be very important for instance for Voice over IP wireless systems, whose payloads are small and thus large IP/UDP/RTP headers would generate an intolerable overhead.The key property of ROHC is the capability to resist to larger packet error rates than classic header compression schemes, which is a necessary virtue in wireless links. The main trick is the capability to recover the transmitted header even if up to W consecutive packets have been lost.There is a quite large amount of simulation studies on the effectiveness of ROHC in literature [1] [3], which extensively investigates the performance of ROHC with respect to many metrics of interest (delay, jitter, error probability, etc.). There has been some work that attempted to explore from an analytical point of view the performance of ROHC [3] [5]. These analytical studies have shed some light into the behavior of ROHC, but rarely do they provide simple mathematical expressions and hence it is hard to infer the qualitative dependence between important design parameters (like W or the timeouts that govern ROHC) to the characteristics of the wireless channels. Moreover, previous work [3] [5] focused on channels which cause independent losses. While a memoryless channel is a useful starting point, wireless channels are often correlated and therefore a problem analysis for correlated channels is just as necessary.In this work we address the previous points with a focus on the ROHC U-mode that is the most relevant for short packets (e.g., VoIP). After an introduction on ROHC in Section II, we provide in Section III an analytical model that, under some simpli cations, enables to get insightful, rst order, closedform expressions for the probability that the decompressor may lose synchronization with the compressor, which will be denoted as out-of-synchronization probability and will be
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