Secrecy Performance of Short-Packet Communications in MultiHop IoT Networks With Imperfect CSI

This letter proposes a best node and random jammer (bN-rJ) scheme for multi-hop Internet-of-Things (IoT) networks under imperfect channel state information (CSI) and non-colluding eavesdroppers. Approximate and asymptotic closed-form expressions for the secrecy block-error rate (SBLER) and secrecy throughput (STP) of the bN-rJ scheme are derived, thereby guiding useful insights into system designs. Numerical results reveal that: 1) For perfect CSI cases, the bN-rJ scheme offers better secrecy improvement than the benchmark ones, especially saving over 10 dB power for SBLER transmission and increasing at least 0.5 bit per channel use in STP performance; 2) For imperfect CSI (iCSI), SBLER can be reduced significantly when using node selection strategy, for example, on average reduction of
$2\times 10^{-1}$
with 10 nodes at an iCSI level of 0.6; 3) The optimal transmission hop of the bN-rJ scheme under perfect CSI is always larger than its counterpart under iCSI at least 1 hop in STP evaluation.