  We analyse the performance of a communication link assisted by an intelligent
reflective surface (IRS) positioned in the far field of both the source and the
destination. A direct link between the transmitting and receiving devices is
assumed to exist. Perfect and imperfect phase adjustments at the IRS are
considered. For the perfect phase configuration, we derive an approximate
expression for the outage probability in closed form. For the imperfect phase
configuration, we assume that each element of the IRS has a one-bit phase
shifter (0{\deg}, 180{\deg}) and an expression for the outage probability is
obtained in the form of an integral. Our formulation admits an exact asymptotic
(high SNR) analysis, from which we obtain the diversity orders for systems with
and without phase errors. We show these are N + 1 and (N + 3)/2, respectively.
Numerical results confirm the theoretical analysis and verify that the reported
results are more accurate than methods based on the central limit theorem
(CLT).
