Ernst Eberlein

State modelling of the land mobile propagation channel for dual-satellite systems

The quality of service of mobile satellite reception can be improved by using multi-satellite diversity (angle diversity). The recently finalised MiLADY project targeted therefore on the evaluation and modelling of the multi-satellite propagation channel for land mobile users with focus on broadcasting applications. The narrowband model combines the parameters from two measurement campaigns: In the U.S. the power levels of the Satellite Digital Audio Radio Services were recorded with a high sample rate to analyse fast and slow fading effects in great detail. In a complementary campaign signals of Global Navigation Satellite Systems (GNSS) were analysed to obtain information about the slow fading correlation for almost any satellite constellation. The new channel model can be used to generate time series for various satellite constellations in different environments. This article focuses on realistic state sequence modelling for angle diversity, confining on two satellites. For this purpose, different state modelling methods providing a joint generation of the states ‘good good’, ‘good bad’, ‘bad good’ and ‘bad bad’ are compared. Measurements and re-simulated data are analysed for various elevation combinations and azimuth separations in terms of the state probabilities, state duration statistics, and correlation coefficients. The finally proposed state model is based on semi-Markov chains assuming a log-normal state duration distribution.

Channel Modeling for Multiple Satellite Broadcasting Systems

In this contribution we present the results of a study on land mobile satellite channel models for satellite systems with multiple satellites. The slow fading of our channel model for several satellites is based on a Markov channel state model for joint processes while the probability density function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The correlation between two satellite channels and the channel spatial autocorrelation have also been studied. We show that a channel state model that uses a Markov state model of order one or of a fixed higher order is not appropriate if the state duration is of very high importance, which can be the case in the process of system planning. Therefore, we propose a dynamic higher order Markov state model for joint processes that depends on the current state duration. This approach models precisely any PDF of the channel state duration for both single and multiple satellite broadcasting systems while having a significantly lower computational complexity than a fixed higher order Markov model. It models the channel states of the whole system correctly, as well as the channel states of each satellite observed independently. It is able to capture the state correlation between multiple satellites. We also study possible approximations of the proposed models in order to reduce their computational complexity while having a good PDF match. Our channel state models are validated by measurements.

Mobile satellite broadcasting with angle diversity - performance evaluation based on measurements

This paper focuses on the achievable angle diversity gain in mobile satellite broadcasting in various environments. Multiple satellite signals within the S-band were recorded simultaneously along the east coast of the U.S. over a traveling distance of 3700 km. The first-order statistical data analysis shows that the required C/N margin for a certain service availability can be significantly decreased by combining two satellite signals. Depending on their elevation angles, the diversity combining gain is analyzed in terms of cumulative distribution functions (CDFs) for various environments. The results for angle diversity are compared to time diversity using an interleaver of variable length. Combining angle diversity and time interleaving results in a further improvement of the service availability.

MIMOSA–a dual approach to detailed land mobile satellite channel modeling

SUMMARY As multiple-input-multiple-output (MIMO) transmission technologies are common in terrestrial mobile communications and getting attention for mobile broadcasting satellite systems, the need for a comprehensive MIMO channel model for the dual-polarized land mobile satellite (LMS) channel arises. In the course of the Characterisation of the MIMO Channel for Mobile Satellite Systems (MIMOSA) project, two complementary modeling approaches have been developed that form a dual model. They provide a scalable modeling solution, which permits a user selectable level of simulation complexity and detail. The models have been evaluated by comparing their results with data gathered from the extensive field trials carried out within the MIMOSA project. This paper describes the dual wideband-modeling and narrowband-modeling approaches, provides examples of the usage and provides some evaluation results. Copyright

MIMOSA --Analysis of the MIMO channel for LMS systems

MIMO systems are already state-of-the-art in terrestrial systems. With the availability of satellites with higher EIRP the high spectrum efficiency offered by MIMO systems becomes applicable to satellite-based systems, too. The MIMOSA project covers the evaluation of the satellite MIMO channel characteristics by field measurements. In particular, the estimated capacity increase for mobile reception is evaluated. The measurements have been completed, but the analysis is still ongoing. This paper describes the measurement setup and includes selected results from the statistical analysis.

Choice of physical layer code rate and modulation for DVB-SH

This paper assesses the spectral efficiencies that can be achieved in theory and simulation for several channel models, and where the same spectral efficiencies can result from different combinations of the signal constellation and channel code rate. A trade-off analysis is presented both for satellite and terrestrial channels for the impact on the spectral efficiency G of increasing the modulation order and at the same time reducing the code rate.

Channel state modeling for single and multiple satellite broadcasting systems

In this contribution, we present the results of a study of the Probability Density Function (PDF) of the state durations in satellite broadcasting systems. We show that a channel state model that uses a Markov state model of order one is not appropriate if the state duration is of high importance, which can be the case in the process of system planning. In this case, a dynamic higher order Markov state model can be used. We study the modeling of the channel state duration for both single and multiple satellite broadcasting systems. In case of multiple satellite systems the channel state modeling is performed based on a dynamic higher order Markov channel state model for joint processes that depends on the current state duration. This approach is able to model the channel states of the whole system correctly, as well as the channel states of each satellite observed independently, showing the ability of capturing the state correlation between multiple satellites. Moreover, we introduce a reduced complexity channel state generation algorithm based on the PDF of the state duration. Our channel state models are validated with measurements of the Satellite Digital Audio Radio Services (S-DARS) system XM Radio carried out on various locations in the USA and Canada.

Adding different levels of QoS to the DVB-SH standard

We propose and analyze two strategies to provide different levels of quality of service (QoS) to the DVB-SH standard. An extension of the interleaving scheme is investigated to support low latency service requirements for interactive services based on short messages. The first approach is a straightforward extension of the DVB-SH interleaver scheme based on an early-uniform interleaver profile, and the second one is the introduction of a super short interleaver, referred to as molded interleaver, which is embedded inside the standard DVB-SH interleaver. An exhaustive analysis, based on laboratory measurements, shows the benefits of the molded interleaver. Finally a comparison between the modified interleaving strategy and the use of hierarchical modulation is presented.

State Modelling of the Land Mobile Propagation Channel with Multiple Satellites

We evaluate a new approach for multisatellite state modelling: the Master-Slave approach. By this concept slave satellites are modelled according to an existing master, whereas the correlation between multiple slaves is omitted. Master-Slave is therefore a generic name for a state modelling concept, for which different realisations are possible. As a possible realisation we present the Conditional Assembling Method. For modelling of only two satellites (one master and one slave), the Conditional Assembling Method enables an accurate resimulation of the correlation coefficient between the satellites and the probabilities of single and combined states. Based on this condition, the performance of Master-Slave for three, four, and five satellites is evaluated in terms of state probability modelling. Therefore, the correlation coefficients and the all bad-state probabilities with Master-Slave are compared with the measurements for different elevation angles and azimuth angle separations of the multisatellite system. Master-Slave has a high modelling error in case of small azimuth separation between the slave satellites (except that one slave has a small azimuth separation to the master). Furthermore, a master satellite with a high elevation provides a lower probability error compared to a master with low elevation.

QoS prediction for mobile satellite broadcasting with angle diversity based on measurements

To meet the high quality of service requirements for mobile satellite applications, diversity combining techniques are used to mitigate fading effects in the satellite propagation channel. In this paper the performance of multi-satellite diversity (or angle diversity) in combination with time diversity is presented. The achievable diversity gain depends on the environmental conditions, the satellite elevation and the angular separation of the satellites. To assess the performance of multi-satellite systems, high-power broadcasting signals in the S-band from HEO and GEO satellites of the Sirius XM Radio system were recorded simultaneously along the east coast of the USA. Based on the measured signal power levels, the ESR(5) fulfillment criteria are predicted for various configurations incorporating different margins, time interleaver lengths, and satellite constellations. The results are presented for six different environments: urban, suburban, commercial, forest, intermediate tree shadowed, and highway.