  This letter investigates joint power control and user clustering for downlink
non-orthogonal multiple access systems. Our aim is to minimize the total power
consumption by taking into account not only the conventional transmission power
but also the decoding power of the users. To solve this optimization problem,
it is firstly transformed into an equivalent problem with tractable
constraints. Then, an efficient algorithm is proposed to tackle the equivalent
problem by using the techniques of reweighted 1-norm minimization and
majorization-minimization. Numerical results validate the superiority of the
proposed algorithm over the conventional algorithms including the popular
matching-based algorithm.
