  We enhance the physical-layer security (PLS) of amplify-and-forward relaying
networks with the aid of joint relay and jammer selection (JRJS), despite the
deliterious effect of channel state information (CSI) feedback delays.
Furthermore, we conceive a new outage-based characterization approach for the
JRJS scheme. The traditional best relay selection (TBRS) is also considered as
a benchmark. We first derive closed-form expressions of both the connection
outage probability (COP) and of the secrecy outage probability (SOP) for both
the TBRS and JRJS schemes. Then, a reliable-and-secure connection probability
(RSCP) is defined and analyzed for characterizing the effect of the correlation
between the COP and SOP introduced by the corporate source-relay link. The
reliability-security ratio (RSR) is introduced for characterizing the
relationship between the reliability and security through the asymptotic
analysis. Moreover, the concept of effective secrecy throughput is defined as
the product of the secrecy rate and of the RSCP for the sake of characterizing
the overall efficiency of the system, as determined by the transmit SNR,
secrecy codeword rate and the power sharing ratio between the relay and jammer.
The impact of the direct source-eavesdropper link and additional performance
comparisons with respect to other related selection schemes are further
included. Our numerical results show that the JRJS scheme outperforms the TBRS
method both in terms of the RSCP as well as in terms of its effective secrecy
throughput, but it is more sensitive to the feedback delays. Increasing the
transmit SNR will not always improve the overall throughput. Moreover, the RSR
results demonstrate that upon reducing the CSI feedback delays, the reliability
improves more substantially than the security degrades, implying an overall
improvement in terms of the security-reliability tradeoff.
