The transmitted signals in non-orthogonal multiple access (NOMA) schemes can
have substantial envelope °uctuations, not to mention the inherent high interference levels. This
means that a high price in terms of power e±ciency can be payed to achieve the substantial ca-
pacity gains of NOMA systems. In this paper we consider the use single-carrier signals combined
with NOMA schemes in the downlink transmission. We present a multi-antenna transmission
technique that is compatible with the use of high-e±ciency power ampli¯ers and does not re-
quire any pre-processing and allows the use of power-e±cient ampli¯ers. Moreover, an e±cient
detection is achieved using iterative receivers with joint multi-user detection and equalization.
Our performance results show that the proposed technique allows high power e±ciency, with
bit-error-rate (BER) performance close to the matched ¯lter bound (MFB)