  Multi-replicA decoding using corRelation baSed LocALisAtion (MARSALA) is a
recent random access technique designed for satellite return links. It follows
the multiple transmission and interference cancellation scheme of Contention
Resolution Diversity Slotted Aloha (CRDSA). In addition, at the receiver side,
MARSALA uses autocorrelation to localise replicas of a same packet so as to
coherently combine them. Previous work has shown good performance of MARSALA
with an assumption of ideal channel state information and perfectly coherent
combining of the different replicas of a given packet. However, in a real
system, synchronisation errors such as timing offsets and phase shifts between
the replicas on separate timeslots will result in less constructive combining
of the received signals. This paper describes a method to estimate and
compensate the timing and phase differences between the replicas, prior to
their combination. Then, the impact of signal misalignment in terms of residual
timing offsets and phase shifts, is modeled and evaluated analytically.
Finally, the performance of MARSALA in realistic channel conditions is assessed
through simulations, and compared to CRDSA in various scenarios.
