1,515 research outputs found
Satellite-derived Time for Enhanced Telecom Networks Synchronization: the ROOT Project
Satellite-derived timing information plays a determinant role in the provisioning of an absolute time reference to telecommunications networks, as well as in a growing set of other critical infrastructures. In light of the stringent requirements in terms of time, frequency, and phase synchronization foreseen in upcoming access network architectures (i.e., 5G), Global Navigation Satellite System (GNSS) receivers are expected to ensure enhanced accuracy and reliability not only in positioning but also in timing. High-end GNSS timing receivers combined with terrestrial cesium clocks and specific transport protocols can indeed satisfy such synchronization requirements by granting sub-nanosecond accuracy. As a drawback, the network infrastructure can be exposed to accidental interferences and intentional cyber-attacks. Within this framework, the ROOT project investigates the effectiveness and robustness of innovative countermeasures to GNSS and cybersecurity threats within a reference network architecture
A Survey of Clock Synchronization Over Packet-Switched Networks
Clock synchronization is a prerequisite for the realization of emerging applications in various domains such as industrial automation and the intelligent power grid. This paper surveys the standardized protocols and technologies for providing synchronization of devices connected by packet-switched networks. A review of synchronization impairments and the state-of-the-art mechanisms to improve the synchronization accuracy is then presented. Providing microsecond to sub-microsecond synchronization accuracy under the presence of asymmetric delays in a cost-effective manner is a challenging problem, and still an open issue in many application scenarios. Further, security is of significant importance for systems where timing is critical. The security threats and solutions to protect exchanged synchronization messages are also discussed
Improvement of mobile trilateration accuracy with modified geo-location techniques.
Masters Degree. University of KwaZulu-Natal, Durban.Abstract available in pdf
Hybrid Millimeter-Wave Systems: A Novel Paradigm for HetNets
Heterogeneous Networks (HetNets) are known to enhance the bandwidth
efficiency and throughput of wireless networks by more effectively utilizing
the network resources. However, the higher density of users and access points
in HetNets introduces significant inter-user interference that needs to be
mitigated through complex and sophisticated interference cancellation schemes.
Moreover, due to significant channel attenuation and presence of hardware
impairments, e.g., phase noise and amplifier nonlinearities, the vast bandwidth
in the millimeter-wave band has not been fully utilized to date. In order to
enable the development of multi-Gigabit per second wireless networks, we
introduce a novel millimeter-wave HetNet paradigm, termed hybrid HetNet, which
exploits the vast bandwidth and propagation characteristics in the 60 GHz and
70-80 GHz bands to reduce the impact of interference in HetNets. Simulation
results are presented to illustrate the performance advantage of hybrid HetNets
with respect to traditional networks. Next, two specific transceiver structures
that enable hand-offs from the 60 GHz band, i.e., the V-band to the 70-80 GHz
band, i.e., the E-band, and vice versa are proposed. Finally, the practical and
regulatory challenges for establishing a hybrid HetNet are outlined.Comment: 12 pages, 5 Figures, IEEE Communication Magazine. In pres
- …