Impact Of Velocity Variations Research Articles

A Novel Segment-Based Model for Non-Stationary Vehicle-to-Vehicle Channels With Velocity Variations

By considering the velocity variations of both terminals and moving scatterers, a general segment-based model for non-stationary vehicle-to-vehicle (V2V) channels is proposed in this paper. The time evolving channel parameters, i.e., Doppler frequencies, angles of arrival and departure, path delays, and path powers, are analyzed and simplified by the Taylor series expansions. The proposed model can be applied for realistic V2V communication environments and explicitly reveal the impact of velocity variations on the channels. In addition, the theoretical statistical properties, i.e., the temporal correlation function (TCF), Doppler power spectrum density (DPSD), level-crossing rate (LCR), and average fading duration (AFD) are also analyzed and derived. Simulation results under four typical V2V scenarios show that the theoretical results agree well with the simulated and measured ones, which verifies the effectiveness of both the proposed model and the derivations.

Seawater velocity variations and real-time reservoir monitoring

As industry moves toward exploring and producing in deeper water areas, the impact of velocity variations in the water layer will become more critical. Acquisition crews are very much aware of this phenomenon. For example it is known that large salinity variations caused by salt seabed outcrop or fresh river water dumping can introduce velocity contrasts strong enough to create a reflection in the water column (such as the 3 s brine reflection in the Orca Basin, Gulf of Mexico) or can affect the balance of towed streamers. On the other hand, this problem requires more careful examination than is currently being undertaken by processing geophysicists and interpreters: Only the issue of velocity variations between infill and original acquisitions has been studied (Wombell, 1997 and MacKay and Fried, 2002).