Spread Asynchronous Scrambled Coded Multiple Access (SA-SCMA) - A New Efficient Random Access Method

摘要

Asynchronous Scrambled Coded Multiple Access (A-SCMA) has been shown to offer high spectral efficiencies on Random Access (RA) channels. This paper describes a new multiple access scheme, SA-SCMA, that adds spreading. Even modest spreading provides significant gains in spectral efficiency, while the use of large RRC rolloff combined with adjacent channel interference cancellation (ACIC) further enhances performance. Spectral efficiencies achieved are high enough to offer data transfer over RA, eliminating the usual 2-way propagation delay needed to assign resources, lowering latency, an important consideration for geostationary satellite inroutes (return links). Additionally, spreading reduces flux density, enabling smaller antenna apertures needed for lower cost applications. The use of SA-SCMA on a saturated radio to further reduce user terminal cost is also discussed.