An energy efficient CDMA scheme for in-situ communications on Mars

To extend the battery life of a Martian surface unit it is desired to minimize the energy consumed by the surface to orbit communications transceiver. The performance of three different transmission schemes are evaluated in terms of the energy-per-bit required by the transmit power amplifier to achieve a desired energy-per-bit at the receiver. A fixed-power variable-rate transmission scheme is shown to provide the largest savings in energy. Using this as the basis for selecting a multiple access system, a code division multiple access system is presented and its performance is analyzed.