  An intelligent omni-surface (IOS) assisted holographic multiple-input and
multiple-output architecture is conceived for $360^\circ$ full-space coverage
at a low energy consumption. The theoretical ergodic rate lower bound of our
non-orthogonal multiple access (NOMA) scheme is derived based on the moment
matching approximation method, while considering the signal distortion at
transceivers imposed by hardware impairments (HWIs). Furthermore, the
asymptotically ergodic rate lower bound is derived both for an infinite number
of IOS elements and for continuous aperture surfaces. Both the theoretical
analysis and the simulation results show that the achievable rate of the NOMA
scheme is higher than that of its orthogonal multiple access counterpart.
Furthermore, owing to the HWIs at the transceivers, the achievable rate
saturates at high signal-to-noise ratio region, instead of reaching its
theoretical maximum.
