AES and Mixed AES/Gold Spreading Sequences for Satellite Uplink Code Division Multiplexing

Abstract

In this paper we study spreading sequences for Code Division Multiplexing (CDM) generated from the AES algorithm in counter mode. These sequences are robust against jamming because they cannot be reconstructed from one of their segments. Additionally, they are flexible, have a large cardinality, and can be obtained from a small key. We show how their linear complexity profile, error probability, and acquisition performance are aligned with those of random sequences. To further enhance them, we introduce a new family of mixed AES/Gold sequences. First, we demonstrate how we can generate cosets of extended Gold sequences which are perfectly orthogonal for CDM. Then, we combine AES sequences and Gold cosets: the new sequences have better performance in terms of error probability and acquisition, while maintaining protection against jamming. All results are derived analytically and validated through simulation. As a case study, we consider an uplink scenario from a ground station to a constellation of Low Earth Orbit satellites. The proposed mixed sequences allow for a significant increase in the number of satellites that can be served in parallel, while maintaining the same level of performance and protection against jamming.