Broadband Satellites: Defining Efficiency and Flexibility to Drive 5G (Part 11)

By Andrew Aroh

USING KA-BAND BROADBAND SATELLITE FOR HIGH EFFICIENCIES AND FLEXIBILITY REQUIRED FOR 5G

• To obtain on-orbit flexibility as required for 5G there are certain stringent constraints that are required for commercial communications satellite payloads:
  • Size
  • Mass
  • Cost
  • Power consumption
  • Reliability
  • Technical risk
  • In digital realization of the payload, we are looking at high-speed/low power characteristics while having radiation hardness.
• Microwave capabilities for SATCOM upper Microwave assemblies are advancing as designers have developed a number of integrated converters for frequencies up to 100GHz and more.
• Thus, the topology of a LEO-based Network has become very dynamic and uses fast-packet switching suitable for 5G
• For the Ka-band as well as the V-band systems, there are four main features required for high efficiency operations:
  • Higher beam power
  • Higher bandwidths
  • Conduction cooling
  • An enabling technology including AIS and ACM
• AIS (Automatic in route Selection) and ACM (Adaptive Code Modulation) enables a dynamic process through which the hub assess how much power the remote site needs to receive and send information in unfavourable weather conditions, enabling the highest efficiency of operations possible, all the time.

SPECIAL FEATURES OF ADVANCED COMMUNICATIONS SATELLITE PAYLOADS:

• Flexible multiple spot-beam combinations made possible by the large digital processor which provides.
  • Switching and beam forming network with reconfigurable coverage
  • Power flexibility between beams; a key technology for advanced Global Mobile Personal Communications (GMPCS); Broadcast and Military Mission.
• Multibeam active Antennas and onboard processing and switching make an ideal combination to provide the required full crossbeam connectivity and flexible traffic routing to drive 5G broadband LEO Satellites.

SUMMARY:

SATELLITE SWITCHING

Modern satellite systems frequently require multibeam operation to meet the link budget requirements. in these systems there is of course no guarantee that traffic originating in one uplink beam will be destined for the same downlink beam. The satellite transponder must provide interconnections between beams.

These connections must be selectable to allow for varying traffic patterns. In a TDMA system the time of arrival of an uplink signal at the satellite transponder determines its eventual destination; if the routing is defined on the satellite (i.e. satellite switched TDMA) the transponder must also perform a time-dependant beam switching.

ON-BOARD PROCESSING

The most advanced transponder types currently being designed may require additional forms of processing, for example, the so-called ‘switch-board in the sky’ systems move the central switching node of a communication system from the ground into space. In such a transponder, signals are demodulated prior to switching in complex time and space matrices.

When on-board processing is employed, it is possible to separately optimized up-and downlinks, by demodulating and then re-modulating in the transponder. Military transponders may require special forms of on-board processing to reject deliberate jamming by hostile forces.

Andrew Aroh is President SSPI Nigeria