Alan Couchman - Academia.edu (original) (raw)
Papers by Alan Couchman
24th AIAA International Communications Satellite Systems Conference, 2006
When considering the inherent uncertainty of the broadband communication market evolution as well... more When considering the inherent uncertainty of the broadband communication market evolution as well as the spatial non-uniform distribution of capacity requests through the satellite coverage, flexibility to adapt to different traffic configurations is a key requirement for future satellite systems to maintain their competitiveness. Beam hopping solutions appear as good candidates to match system offered capacity with traffic demand. Although the introduction of flexible bandwidth and power allocation to beams brings some benefits in terms of demand satisfaction for hot spots with respect to traditional systems with regular frequency reuse and equal power to beam allocation, utilization of beam hopping techniques offers an additional mean to cope with irregular and time variant traffic distributions. In this paper the forward link of a multibeam transparent satellite system for providing broadband Internet access to users sparse over the coverage area is analyzed. The utilization of Adaptive Coding and Modulation (ACM) techniques is considered, according to the recently approved DVB-S2 standard. The advantage in terms of system performance brought by the utilization of beam hopping techniques is assessed. In this type of system, only a few beams of the overall coverage are selected at each time-slot for transmission. This set of illuminated beams changes on a slot-by-slot basis over the duration of a repetition window. This creates a time and spatial transmission plan that repeats periodically with a given duty cycle. In the present contribution the problem of optimizing the beam hopping transmission plan in order to best match the traffic demand is tackled. Genetic algorithms appear as the most suited optimization tool because of their global optimization nature, their capability of working with a large number of optimization parameters and their suitability to accept a discontinuous figure of merit function. Extensive simulations have been carried out to adapt genetic algorithms functions and parameters to the problem under investigation. The target has been optimizing the beam allocation in the transmission plan to maximize system capacity. System performance is assessed considering the traffic demand distribution over Europe foreseen for broadband satellite services in 2015, as derived by recent market analysis studies. A throughput increase of about 30% compared to a system with regular power and bandwidth allocation capabilities is achieved. The impact of a beam hopping type of system at payload level is then investigated. In particular, efficient ways to implement beam hopping combining payload flexibility with affordable complexity are investigated. Both Direct Radiating Array (DRA) and Array Fed Reflector (AFR) solutions are considered.
In order to compete with terrestrial services, satellite systems for broadband access networks mu... more In order to compete with terrestrial services, satellite systems for broadband access networks must maximise the useful capacity provided by each satellite. The High Throughput system has been carefully optimised in terms of capacity as part of an ESA R&D contract. This system provides Kaband links between approximately one hundred user beams and a network of gateway stations over a regional European coverage from geostationary orbit. On-board digital processing is essential in providing the routing and frequency plan flexibility needed to use the resources efficiently across so many spot beams. Despite the large bandwidths involved, recent advances in ASIC, mixed signal conversion and digital interconnect technologies, make a fully processed payload handling up to 50 GHz of processed bandwidth feasible in the relatively near term. As well as fine channel demultiplexing, fully flexible routing and gain control, the digital processor also supports digital beamforming across a 500 MHz...
Method of maintaining isolation within a multiport amplifier for satelitede communications, compr... more Method of maintaining isolation within a multiport amplifier for satelitede communications, comprising multiport amplifier a plurality of deamplificador units microwave power, a plurality of input ports and a plurality of puertosde output being ports input connected to said amplifier units by a dedivision input signal (INET) network, and wherein the output ports connected to said deamplificador units by dividing network output signal (ONET), wherein said network division ingress policer signal (INET) is configured in a matrix and includes a first hybrid column input (J, K, LM), each hybrid input of the first column connected to a pair of deamplificador adjacent first and second units being ( A1 / A2 ... A7 / A8) of said plurality of amplifier units, so that an input signal at any input port amplified by all deamplificador units, and then recombined into an output signal at an output port, elmetodo comprising: providing at least one of said media drives amplifier gain adjustment and ...
This paper presents possible payload / processor architectures, responding to the requirements of... more This paper presents possible payload / processor architectures, responding to the requirements of the next generation of broadband access networks via satellite, targeting throughputs higher than 50 Gbps. First the transparent satellite access system scenario is described and the main payload and processor requirements are identified. Then the main part of the paper trades off different payload and processor architectures taking into account major constraints such as flexibility, scalability, complexity, mass and power consumption. It identifies respectively “beam port processor architectures” where no beam forming is performed inside the processor and “feed port processor architectures”, which involve digital beam forming. The different payload and antenna front-ends likely to accommodate these processors, such as single feed per beam and array fed-reflectors, are also discussed. Finally system capacity analysis is performed to demonstrate the targeted system performances.
24th AIAA International Communications Satellite Systems Conference, 2006
24th AIAA International Communications Satellite Systems Conference, 2006
When considering the inherent uncertainty of the broadband communication market evolution as well... more When considering the inherent uncertainty of the broadband communication market evolution as well as the spatial non-uniform distribution of capacity requests through the satellite coverage, flexibility to adapt to different traffic configurations is a key requirement for future satellite systems to maintain their competitiveness. Beam hopping solutions appear as good candidates to match system offered capacity with traffic demand. Although the introduction of flexible bandwidth and power allocation to beams brings some benefits in terms of demand satisfaction for hot spots with respect to traditional systems with regular frequency reuse and equal power to beam allocation, utilization of beam hopping techniques offers an additional mean to cope with irregular and time variant traffic distributions. In this paper the forward link of a multibeam transparent satellite system for providing broadband Internet access to users sparse over the coverage area is analyzed. The utilization of Adaptive Coding and Modulation (ACM) techniques is considered, according to the recently approved DVB-S2 standard. The advantage in terms of system performance brought by the utilization of beam hopping techniques is assessed. In this type of system, only a few beams of the overall coverage are selected at each time-slot for transmission. This set of illuminated beams changes on a slot-by-slot basis over the duration of a repetition window. This creates a time and spatial transmission plan that repeats periodically with a given duty cycle. In the present contribution the problem of optimizing the beam hopping transmission plan in order to best match the traffic demand is tackled. Genetic algorithms appear as the most suited optimization tool because of their global optimization nature, their capability of working with a large number of optimization parameters and their suitability to accept a discontinuous figure of merit function. Extensive simulations have been carried out to adapt genetic algorithms functions and parameters to the problem under investigation. The target has been optimizing the beam allocation in the transmission plan to maximize system capacity. System performance is assessed considering the traffic demand distribution over Europe foreseen for broadband satellite services in 2015, as derived by recent market analysis studies. A throughput increase of about 30% compared to a system with regular power and bandwidth allocation capabilities is achieved. The impact of a beam hopping type of system at payload level is then investigated. In particular, efficient ways to implement beam hopping combining payload flexibility with affordable complexity are investigated. Both Direct Radiating Array (DRA) and Array Fed Reflector (AFR) solutions are considered.
In order to compete with terrestrial services, satellite systems for broadband access networks mu... more In order to compete with terrestrial services, satellite systems for broadband access networks must maximise the useful capacity provided by each satellite. The High Throughput system has been carefully optimised in terms of capacity as part of an ESA R&D contract. This system provides Kaband links between approximately one hundred user beams and a network of gateway stations over a regional European coverage from geostationary orbit. On-board digital processing is essential in providing the routing and frequency plan flexibility needed to use the resources efficiently across so many spot beams. Despite the large bandwidths involved, recent advances in ASIC, mixed signal conversion and digital interconnect technologies, make a fully processed payload handling up to 50 GHz of processed bandwidth feasible in the relatively near term. As well as fine channel demultiplexing, fully flexible routing and gain control, the digital processor also supports digital beamforming across a 500 MHz...
Method of maintaining isolation within a multiport amplifier for satelitede communications, compr... more Method of maintaining isolation within a multiport amplifier for satelitede communications, comprising multiport amplifier a plurality of deamplificador units microwave power, a plurality of input ports and a plurality of puertosde output being ports input connected to said amplifier units by a dedivision input signal (INET) network, and wherein the output ports connected to said deamplificador units by dividing network output signal (ONET), wherein said network division ingress policer signal (INET) is configured in a matrix and includes a first hybrid column input (J, K, LM), each hybrid input of the first column connected to a pair of deamplificador adjacent first and second units being ( A1 / A2 ... A7 / A8) of said plurality of amplifier units, so that an input signal at any input port amplified by all deamplificador units, and then recombined into an output signal at an output port, elmetodo comprising: providing at least one of said media drives amplifier gain adjustment and ...
This paper presents possible payload / processor architectures, responding to the requirements of... more This paper presents possible payload / processor architectures, responding to the requirements of the next generation of broadband access networks via satellite, targeting throughputs higher than 50 Gbps. First the transparent satellite access system scenario is described and the main payload and processor requirements are identified. Then the main part of the paper trades off different payload and processor architectures taking into account major constraints such as flexibility, scalability, complexity, mass and power consumption. It identifies respectively “beam port processor architectures” where no beam forming is performed inside the processor and “feed port processor architectures”, which involve digital beam forming. The different payload and antenna front-ends likely to accommodate these processors, such as single feed per beam and array fed-reflectors, are also discussed. Finally system capacity analysis is performed to demonstrate the targeted system performances.
24th AIAA International Communications Satellite Systems Conference, 2006