The Wideband Global Satellite (WGS) offers new wideband MILSATCOM capabilities, especially at Ka-band. Unfortunately, Ka-band is subject to deep rain fades. The WGS satellite offers simultaneous X-band as a potential Ka-band rain fade mitigation path. Antennas are available today which support simultaneous X/Ka-band for rain fade mitigation via frequency diversity. Yet, few operational concepts exist for exploiting this capability. This paper will present network protocol concepts that leverage WGs' advanced X/Ka capabilities and requirements for terminal designs that use frequency diversity rain fade mitigation.

Protocols for rain fade mitigation using simultaneous X/Ka communications

Some Fields of Lens Array Applications

RF and Optical Communications for Small Satellites

This report provides a review and evaluation of rain fade measurement and compensation techniques for Ka-band satellite systems. This report includes a description of and cost estimates for performing three rain fade measurement and compensation experiments. The first experiment deals with rain fade measurement techniques while the second one covers the rain fade compensation techniques. The third experiment addresses a feedback flow control technique for the ABR service (for ATM-based traffic). The following conclusions were observed in this report; a sufficient system signal margin should be allocated for all carriers in a network, that is a fixed clear-sky margin should be typically in the range of 4-5 dB and should be more like 15 dB in the up link for moderate and heavy rain zones; to obtain a higher system margin it is desirable to combine the uplink power control technique with the technique that implements the source information rate and FEC code rate changes resulting in a 4-5 dB increase in the dynamic part of the system margin. The experiments would assess the feasibility of the fade measurements and compensation techniques, and ABR feedback control technique.

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W. Carl Mitchell

Papers

Rain Fade Compensation for Ka-Band Communications Satellites