Spectral sharing in hybrid spot and area coverage satellite systems via channel coding techniques

Multiple spot-beam switching satellites employing frequency reuse are considered, and a method for incorporating an area coverage beam to provide service to those regions not covered by the footprint of any spot beam is proposed here. The method consists of employing a convolutional code for the area beam transmission to enable sharing of a common spectral band among the spot and area beams on a noninterfering basis and with no sacrifice in the capacity of the spot beams. A maximum-likelihood algorithm for this purpose is derived, and bounds on the bit error rate performance of all beams are found. Results show that excessive performance degradation arising from cochannel interference is limited to a thin annular ring surrounding each spot beam.