I. Introduction
Energy-efficient multiple access is the goal in many low-power applications. Wireless sensor nodes are supposed to operate on battery power for long times. For connecting them to a mobile network [1], energy-efficient transmission is required. The same holds for multiple access in passive optical networks (PONs) for fiber to the home (FTTH). Multiple user signals are aggregated in a passive fiber coupler and fed jointly to the central office [2]. In the return channel over satellite (RCS), large numbers of users are served in parallel [3]. The received signal is poor due to low-cost transmitters, small dish antennas and large distance to the satellite.