New Multipath & Co-Channel Interference Suppe\ression Techniques for Digital Data

Co-channel interference (CCI, i.e. interference from like-modulated signals), is rapidly emerging as one of the greatest impacts to new digital data communications systems, both military and commercial. Multiple users in the same frequency band and overlapping geographic locations often impact performance of communications equipment more than noise or more conventional interference. Multipath and dispersive channels firther exacerbate this impact. A new approach to mitigating Co-channel interference in a dispersive environment, applying Per Survivor Processing (PSP), offers the opportunity to achieve large performance improvements (e.g. improved acquisition, &/or interference rejection) over conventional design techniques when a large number of users, difficult dynamics and/or large channel uncertainties are present. Further, PSP excels when the channel characteristics, the number of interferers or reflections, & other key signal parameters are unknown. ViaSat proposes to develop CCI suppression concepts for multipath environments based on PSP techniques, both scalar and vecton Performance will be analyzed and implementation complexity sized and optimized. Comparisons will be made to conventional approaches. Strawman architectures will also be derived. If the Phase I program is successful ViaSat will clearly show that a PSP based CCI suppression scheme is practical and that it can take full advantage of existing commercial technology. BENEFITS: These PSP CCI suppression techniques offer the potential to greatly enhance the number of users and/or cell packing density through improved frequency reuse on commercial TDMA cellular systems. These same techniques can reduce in-band interference for many emerging military communications systems as well as enhance signal collection schemes.