Convolutional Sparse Coding Based Channel Estimation for OTFS-SCMA in Uplink

Orthogonal time frequency space (OTFS) has emerged as the most sought-after modulation technique in a high mobility scenario. Sparse code multiple access (SCMA) is an attractive code-domain non-orthogonal (NOMA) technique. Recently NOMA approach for OTFS, named OTFS-SCMA, proposed. OTFS-SCMA promising framework that meets demands of and massive connectivity. This paper presents channel estimation based on convolutional sparse coding (CSC) uplink. The task formulated CSC problem following careful rearrangement OTFS input-output relation. We use embedded pilot-aided sparse-pilot structure enjoys features both SCMA. existing techniques multi-user scenarios uplink demand extremely overhead pilot guard symbols, proportional to number users. proposed method maintains minimal equivalent single user without compromising error. results show algorithm very efficient bit error rate (BER), normalized mean square (NMSE), spectral efficiency (SE).