Relaying Strategies and Asymptotic Analysis for Half-Duplex Buffer-Aided Serial Relaying Systems

In this letter, we investigate the problem of buffer-aided relaying in multi-hop systems that comprise a source, destination and
$K$
relays equipped with buffers of size
$L$
. We propose three relaying strategies and compare their performances. The three strategies account for the channel and buffer states at every time slot. The first strategy considers only the state of the previous relay buffer, the second accounts for the next relay whereas the third scheme accounts for the previous and next relays’ states. We evaluate the asymptotic performance of the three schemes and we derive closed-form expressions of the diversity order (DO) and average packet delay (APD) for all values of
$K$
and
$L$
. Results show the ability of the three schemes to achieve multiple levels of tradeoff between the performance metrics.