  A non-orthogonal multiple access (NOMA)-aided joint communication, sensing,
and multi-tier computing (JCSMC) framework is proposed. In this framework, a
multi-functional base station (BS) carries out target sensing, while providing
edge computing services to the nearby users. To enhance the computation
efficiency, the multi-tier computing structure is exploited, where the BS can
further offload the computation tasks to a powerful Cloud server (CS). The
potential benefits of employing NOMA in the proposed JCSMC framework are
investigated, which can maximize the computation offloading capacity and
suppress the inter-function interference. Based on the proposed framework, the
transmit beamformer of the BS and computation resource allocation at the BS and
the CS are jointly optimized to maximize the computation rate subject to the
communication-computation causality and the sensing quality constraints. Both
partial and binary computation offloading modes are considered: 1) For the
partial offloading mode, a weighted minimum mean square error based alternating
optimization algorithm is proposed to solve the corresponding non-convex
optimization problem. It is proved that a KKT optimal solution can be obtained;
2) For the binary offloading mode, the resultant highly-coupled mixed-integer
optimization problem is first transformed to an equivalent but more tractable
form. Then, the reformulated problem is solved by utilizing the alternating
direction method of multipliers approach to obtain a nearly optimal solution.
Finally, numerical results verify the effectiveness of the proposed algorithms
and the proposed NOMA-aided JCSMC framework
