  In this paper, two-hop communication between a source and a destination with
the aid of an intermediate relay node is considered. Both the source and
intermediate relay node are assumed to operate under statistical quality of
service (QoS) constraints imposed as limitations on the buffer overflow
probabilities. It is further assumed that the nodes send the information at
fixed power levels and have perfect channel side information. In this scenario,
the maximum constant arrival rates that can be supported by this two-hop link
are characterized by finding the effective capacity. Through this analysis, the
impact upon the throughput of having buffer constraints at the source and
intermediate-hop nodes is identified.
