Multi-carrier network-centric satellite communications modem design

The paper presents concepts for network-centric communications that are matched to the planned wideband gapfiller satellite system (WGSS) and other transponder based satellite communications. Gapfiller satellites will digitally transpond uplinks and downlinks between X- and Ka-band beams using multiple 125 MHz transponders that can be subchannelized into as many as forty-eight 2.6 MHz band segments. The proposed concept is a multi-carrier network-centric (MC-Net) modem design, dubbed the "McNet" modem. One of several key design features is a simplified method of matching the dynamic traffic variations of IP networks to the digital transponder operations (DTO) planned as part the WGSS; the implications of the design are also applicable for analog transponder based satellite systems. The McNet modem is intended to match the needs of the more network-centric terrestrial segments of the DoD global information grid (GIG). The basic premise of the McNet modem is to use an IP LAN and select a simple modulation format, such as QPSK or 8PSK, with multiple carriers, each at a single fixed rate of nominally 3.3 Mbps based on 155 Mbps/47 subchannels within the 125 MHz band segments of the WGSS (one subchannel is reserved for control functions). In addition to providing the capability to increase or decrease bandwidth quickly between X- and Ka-band terminals, the McNet modem provides additional flexibility for remote control operations. Finally, the McNet modem is also consistent with other concepts for a more flexible Ka-band (or any band) terminal design.