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Papers by Madhavendra Richharia
Introduction. Satellite Orbits. Frequency and Propagation Considerations. Communication Link Desi... more Introduction. Satellite Orbits. Frequency and Propagation Considerations. Communication Link Design. Modulation. Coding. Baseband Signals. Multiple Access Techniques. Communication Satellites. Earth Stations. Non-Geostationery Orbit Satellite Systems. Future Trends.
ABSTRACT Mobile satellite telecommunications systems have undergone an enormous evolution in the ... more ABSTRACT Mobile satellite telecommunications systems have undergone an enormous evolution in the last decades, with the interest in having advanced telecommunications services available on demand, anywhere and at any time, leading to incredible advances. The demand for braodband data is therefore rapidly gathering pace, but current solutions are finding it increasingly difficult to combine large bandwidth with ubiquitous coverage, reliability and portability. The BGAN (Broadband Global Area Network) system, designed to operate with the Inmarsat-4 satellites, provides breakthrough services that meet all of these requirements. It will enable broadband connection on the move, delivering all the key tools of the modern office. Recognising the great impact that Inmarsat's BGAN system will have on the European satellite communications industry, and the benefits that it will bring to a wide range of European industries, in 2003 ESA initiated the "BGAN Extension" project. Its primary goals are to provide the full range of BGAN services to truly mobile platforms, operating in aeronautical, vehicular and maritime environments, and to introduce a multicast service capability. The project is supported by the ARTES Programme which establishes a collaboration agreement between ESA, Inmarsat and a group of key industrial and academic institutions which includes EMS, Logica, Nera and the University of Surrey (UK).
Concepts and Technology, 2010
Mobile Satellite Communications, 2014
This paper describes an aeronautical propagation model suitable for evaluating the performance of... more This paper describes an aeronautical propagation model suitable for evaluating the performance of wideband mobile satellite systems (MSS), such as Inmarsat’s Broadband Global Area Network (BGAN) system. Geometry of propagation is combined with estimates of scattered power from sea surface, weighted by antenna directivity, to provide a statistical representation of signals received on an aircraft. Due to the variability in scattered signal levels, propagation delays and angles of arrival, the multi-path statistics are multi-dimensional exhibiting an amplitude-delay-Doppler spread. The amplitude and delay contours of the multi-path are dependent on the propagation geometry. The concentric amplitude iso-contours demonstrate that the highest scattered power arrives from a relatively narrow central region, which differs from the specular point. Since the location of maximum scattering region with respect to the specular point has an elevation angle and sea state dependence, the minimum d...
Mobile Satellite Communications
… communications, 1991
It may be that we are now entering the era of LEO constellation satellite communications after th... more It may be that we are now entering the era of LEO constellation satellite communications after thirty years of domination by the GEO systems. This paper heralds the coming of the new era with a tutorial approach to the system design and trade-offs of LEO constellation system ...
13th International Communication Satellite Systems Conference and Exhibit
The current scenario in Europe is of a well defined Pan European digital cellular system together... more The current scenario in Europe is of a well defined Pan European digital cellular system together with several proposals for land-mobile satellite systems.The integration of a satellite system with the terrestrial system has obvious advantages.This paper investigates the possible synergy of a land mobile satellite system with the Pan European terrestrial digital cellular system.A possible integrated system architecture using the main functional blocks of the terrestrial system is proposed.Alternative satellite systems have been examined and a likely implementation scenario. based on the foreseeable development in the region,has been suggested.
IEEE Global Telecommunications Conference, 1989, and Exhibition. 'Communications Technology for the 1990s and Beyond
An effort was made to study whether the increased survivability, true global coverage, and reduce... more An effort was made to study whether the increased survivability, true global coverage, and reduced path loss of a LEO (low Earth orbit) network could be utilized to give a viable mobile communication system. The architecture of such a network is complex, but it is expected that the use of advanced technology can overcome most limitations. An optimum constellation is considered, and the first three layers of a digital network are examined. Under certain simplifying assumptions it is shown that the proposed configuration is viable and compares favorably with a similar geostationary network with regards to the overall space-segment cost. The cost benefit begins to favor the LEONET for simpler spacecraft. It is also noted that it may be possible to scale down the LEO constellation to a small size so as to provide continuous coverage above ≈70° latitude, where geostationary satellites are ineffective. This hybrid architecture is also likely to minimize interference with geostationary satellite systems in the congested mobile bands
Introduction. Satellite Orbits. Frequency and Propagation Considerations. Communication Link Desi... more Introduction. Satellite Orbits. Frequency and Propagation Considerations. Communication Link Design. Modulation. Coding. Baseband Signals. Multiple Access Techniques. Communication Satellites. Earth Stations. Non-Geostationery Orbit Satellite Systems. Future Trends.
ABSTRACT Mobile satellite telecommunications systems have undergone an enormous evolution in the ... more ABSTRACT Mobile satellite telecommunications systems have undergone an enormous evolution in the last decades, with the interest in having advanced telecommunications services available on demand, anywhere and at any time, leading to incredible advances. The demand for braodband data is therefore rapidly gathering pace, but current solutions are finding it increasingly difficult to combine large bandwidth with ubiquitous coverage, reliability and portability. The BGAN (Broadband Global Area Network) system, designed to operate with the Inmarsat-4 satellites, provides breakthrough services that meet all of these requirements. It will enable broadband connection on the move, delivering all the key tools of the modern office. Recognising the great impact that Inmarsat's BGAN system will have on the European satellite communications industry, and the benefits that it will bring to a wide range of European industries, in 2003 ESA initiated the "BGAN Extension" project. Its primary goals are to provide the full range of BGAN services to truly mobile platforms, operating in aeronautical, vehicular and maritime environments, and to introduce a multicast service capability. The project is supported by the ARTES Programme which establishes a collaboration agreement between ESA, Inmarsat and a group of key industrial and academic institutions which includes EMS, Logica, Nera and the University of Surrey (UK).
Concepts and Technology, 2010
Mobile Satellite Communications, 2014
This paper describes an aeronautical propagation model suitable for evaluating the performance of... more This paper describes an aeronautical propagation model suitable for evaluating the performance of wideband mobile satellite systems (MSS), such as Inmarsat’s Broadband Global Area Network (BGAN) system. Geometry of propagation is combined with estimates of scattered power from sea surface, weighted by antenna directivity, to provide a statistical representation of signals received on an aircraft. Due to the variability in scattered signal levels, propagation delays and angles of arrival, the multi-path statistics are multi-dimensional exhibiting an amplitude-delay-Doppler spread. The amplitude and delay contours of the multi-path are dependent on the propagation geometry. The concentric amplitude iso-contours demonstrate that the highest scattered power arrives from a relatively narrow central region, which differs from the specular point. Since the location of maximum scattering region with respect to the specular point has an elevation angle and sea state dependence, the minimum d...
Mobile Satellite Communications
… communications, 1991
It may be that we are now entering the era of LEO constellation satellite communications after th... more It may be that we are now entering the era of LEO constellation satellite communications after thirty years of domination by the GEO systems. This paper heralds the coming of the new era with a tutorial approach to the system design and trade-offs of LEO constellation system ...
13th International Communication Satellite Systems Conference and Exhibit
The current scenario in Europe is of a well defined Pan European digital cellular system together... more The current scenario in Europe is of a well defined Pan European digital cellular system together with several proposals for land-mobile satellite systems.The integration of a satellite system with the terrestrial system has obvious advantages.This paper investigates the possible synergy of a land mobile satellite system with the Pan European terrestrial digital cellular system.A possible integrated system architecture using the main functional blocks of the terrestrial system is proposed.Alternative satellite systems have been examined and a likely implementation scenario. based on the foreseeable development in the region,has been suggested.
IEEE Global Telecommunications Conference, 1989, and Exhibition. 'Communications Technology for the 1990s and Beyond
An effort was made to study whether the increased survivability, true global coverage, and reduce... more An effort was made to study whether the increased survivability, true global coverage, and reduced path loss of a LEO (low Earth orbit) network could be utilized to give a viable mobile communication system. The architecture of such a network is complex, but it is expected that the use of advanced technology can overcome most limitations. An optimum constellation is considered, and the first three layers of a digital network are examined. Under certain simplifying assumptions it is shown that the proposed configuration is viable and compares favorably with a similar geostationary network with regards to the overall space-segment cost. The cost benefit begins to favor the LEONET for simpler spacecraft. It is also noted that it may be possible to scale down the LEO constellation to a small size so as to provide continuous coverage above ≈70° latitude, where geostationary satellites are ineffective. This hybrid architecture is also likely to minimize interference with geostationary satellite systems in the congested mobile bands