An enhanced Markov chain based model for the narrowband LMS channel in built-up areas

Abstract

SUMMARYIn this paper, a technique to derive the transition probabilities for a Markov chain model for the land mobile satellite (LMS) channel in built-up areas is presented. This technique contributes to improving empirically derived parameters in that it can account for elevation and street orientation effects as well as building density. Physical-statistical or 'virtual city' techniques are used to relate observed edification statistics to signal attenuation statistics. This methodology can also be applied to generating correlated time-series for simultaneous links to a constellation of satellites from the same mobile terminal. The proposed approach also allows the generation of enhanced time-series which take into account diffuse multipath and diffraction effects.

Hybrid propagation channel modelling for city area land mobile satellite communications

“…The NLOS severe state is largely distributed from -240 to 187 dBW, indicating severe fading and rapid signal fluctuations. These observations are conform to previous studies like [7,11] and lead to the studies of the next section.…”

“…For example, instead of generating virtual environments, we use some of the environment characteristics in [6,12] in order to classify our deterministic city environments. Different receiving states, as proposed in [7,10,11] are also observed in our simulated deterministic signals. Here, the novelty of our study lies in the deterministic state-locating method.…”

“…Using a ray tracing technique (deterministic), Rician parameters (statistical) were proved to be related to building height, street width and other terrain parameters. In [7][8][9], virtual propagation environments can be generated according to physical-statistical environment classification. This study, as well as [10], shows that different receiving states related to Line-Of-Sight (LOS) and Non-Line-OfSight (NLOS) may exist and can be modelled by a Markov chain simulator, whereas the global signal variations within each state was predicted by the Loo distribution [3].…”

“…Here, the novelty of our study lies in the deterministic state-locating method. Moreover, the NLOS severe state ("blocked"), which was not considered in specific applications like [7,11], is taken into account and thus makes the model general. Statistical parameters are estimated and validated according to different environment classes and satellite positions.…”

Simplifying the propagation environment representation for LMS channel modelling

“…The future channel simulator shall be able to generate synthetic time-series for simulation needs with a specific attention on the wideband representation of the channel for Global Navigation Satellite Systems (GNSS) studies. A hybrid approach associating a virtual city [1] and a simplified physical ElectroMagnetic (EM) model has been retained. To extract such simplified EM model, numerical tools are to be used instead of extensive measurements campaigns.…”