  This paper derives upper and lower bounds on the capacity of the
multiple-input single-output free-space optical intensity channel with
signal-independent additive Gaussian noise subject to both an average-intensity
and a peak-intensity constraint. In the limit where the signal-to-noise ratio
(SNR) tends to infinity, the asymptotic capacity is specified, while in the
limit where the SNR tends to zero, the exact slope of the capacity is also
given.
