LMS Markov model and its use for power control error impact analysis on system capacity

We present a wideband land mobile satellite channel model based on a three-state Markov chain model valid for any kind of satellite constellation and for L, S, and Ka bands. Data from measurement campaigns was used to extract the parameters for the statistical distributions involved in the model. We also present a methodology describing how to use the proposed channel model to interface with system-level analysis. We use the time series generated by the model to parameterize power control (PC) imperfection as a function of the environment and user speed by acting upon the time series through a seven-level PC algorithm. We then apply the obtained parameterization to the analysis of a direct sequence-code division multiple-access scenario with users requiring different quality-of-service (QoS). It is shown that request of different QoS produces an unbalance in the users power distribution and less users can be served with the most demanding QoS. PC error worsens this effect and considerably reduces capacity efficiency which is highly dependent on the environment and mobile speed. Bit-error rate statistics are also investigated through the log-normal characterization obtained by using the channel model obtaining results on the effect of required E/sub b//(N/sub o/+I/sub o/) of a particular user.     

Statistical modeling of the LMS channel

In this paper, a statistical model for the land mobile satellite (LMS) channel is presented. The model is capable of describing both narrow- and wide-band conditions. The other relevant characteristic is that it can be used to study links with geostationary as well as nongeostationary satellites. The model is of the generative type, i.e., it is capable of producing time series of a large number of signal features: amplitudes, phases, instantaneous power-delay profiles, Doppler spectra, etc. Model parameters extracted from a comprehensive experimental data bank are also provided for a number of environments and elevation angles at L-, S-, and Ka-bands     

Availability of systems based on satellites with spatial diversityand HAPS

A new simple analytical procedure to calculate availability of systems based either on satellites or a high altitude platform station (HAPS) is introduced. The method is based on the statistical comparison of the angles involved in the links, elevations provided by the system and the masking angles of the surrounding skyline     

Cross-Layer Design of Dynamic Bandwidth Allocation in DVB-RCS

In this paper, a novel cross-layer framework for optimizing the dynamic bandwidth allocation (DBA) of a digital video broadcast (DVB)-return channel satellite (RCS) system using adaptive coding is proposed. The design of the medium access control (MAC) methods taking into account the adaptive physical layer and higher layers' quality of service (QoS) requirements is cast as an optimization problem by using the network utility maximization (NUM) framework applied within the satellite subnetwork. Hierarchical and global solving procedures fully compliant with the DVB-RCS standard are proposed. They do not only provide minimum bandwidth guarantees but also maximize fairness. Further, they allow a joint optimization of the time slot size and overall system efficiency while minimizing signalling overhead. A reduced computational complexity algorithm to solve the DBA problem is presented. In practical terms, it increases the number of connections with absolute and relative QoS requirements the system can manage and facilitates the interoperability of the satellite network within an Internet protocol (IP) environment.     

S-band LMS propagation channel behaviour for differentenvironments, degrees of shadowing and elevation angles

Experimental land mobile satellite (LMS) propagation data have been processed in order to characterise the behaviour of this channel under narrow-band transmission conditions for different environments, degrees of shadowing and elevation angles. Measurements were carried out at S-band. The transmitter was located on a small plane flying parallel to the road with elevations ranging from 40° to 80°. For the analysis of the received amplitude series, they were classified for each environment and elevation angle, into three different states according to the degree of shadowing experienced. This was done in order to develop a Markov chain based propagation simulator. The global (slow+fast) signal variations within each state are modelled using the Loo distribution (Rice+log-normal). Average distribution parameter values for each state, elevation angle and environment type are reported. The average state probabilities, slow variations' correlation lengths and other parameters are also presented. Finally, a software implementation is described based on a Markov chain+Loo distribution model that is capable of reproducing the complex envelope variations in the received signal due to shadowing and multipath