Trellis-Coded Multiple-Access using chirp signalling

This paper introduces a novel Trellis Coded Multiple Access (TCMA) technique which takes advantage of Trellis-Coded Modulation (TCM) and signalling set redundancy to differentiate transmissions from different users. The proposed TCMA scheme exploits modulation with memory principles to provide the flexibility of accommodating an increasing number of users within the fixed time-frequency resource. In the scheme, users are assigned unique, code-based trellises employing distinct subsets of generic signals. This paper focuses on the applicability of chirp signalling to TCMA, even though the proposed system can use other types of narrowband modulations, such as FSK or QAM. Specifically, the MA scheme presented in this paper features the assignment of overlapping, dissimilar signal trellises that efficiently occupy the system bandwidth and allow for (i) user identification and (ii) reliable data recovery. Careful design of a chirp signalling scheme and the trellis arches guiding the frequency hopping patterns is conducted to reduce MAI. An effective demodulation algorithm is developed using the Viterbi decoder incorporated with a parallel, iterative MAI cancellation scheme. It is demonstrated with a theoretical analysis and simulations that the proposed scheme achieves an acceptable bit error rate performance for different system configurations.