Revisiting Lightweight Encryption for IoT Applications: Error Performance and Throughput in Wireless Fading Channels with and without Coding

© 2013 IEEE. Employing heavy conventional encryption algorithms in communications suffers from added overhead and processing time delay; and in wireless communications, in particular, suffers from severe performance deterioration (avalanche effect) due to fading. Consequently, a tremendous reduction in data throughput and increase in complexity and time delay may occur especially when information traverse resource-limited devices as in Internet-of-Things (IoT) applications. To overcome these drawbacks, efficient lightweight encryption algorithms have been recently proposed in literature. One of those, that is of particular interest, requires using conventional encryption only for the first block of data in a given frame being transmitted. All the information in the remaining blocks is transmitted securely without the need for using heavy conventional encryption. Unlike the conventional encryption algorithms, this particular algorithm achieves lower overhead/complexity and higher data throughput. Assuming the additive white Gaussian noise (AWGN) channel, the performance of the lightweight encryption algorithm under study had been evaluated in literature in terms of throughput under the assumption that the first block, that undergoes conventional encryption, is free of error, which is practically unfeasible. In this paper, we consider the AWGN channel with Rayleigh fading and assume that the signal experiences a certain channel bit error probability and investigate the performance of the lightweight encryption algorithm under study in terms of bit error probability and throughput. We derive analytical expressions for these performance metrics considering modulated signals with and without coding. In addition, we propose an extension to the lightweight encryption algorithm under study by further enhancing its security level without significantly affecting the overhead size and processing time. Via numerical results we show the superiority of the lightweight encryption algorithm under study over the conventional encryption algorithms (like the AES) and the lightweight encryption algorithms proposed in literature in terms of error and throughput performance

Accurate Closed-Form Approximations for the BER of Multi-Branch Amplify-and-Forward Cooperative Systems with MRC in Rayleigh Fading Channels

Abstract: -Relay-based cooperative systems have recently attracted significant attention since they enable exploiting the inherent spatial diversity of wireless networks with single antenna terminals. In this paper, the authors address the error performance of a cooperative diversity network consisting of a source, a destination, and multiple dual-hop amplify-and-forward (AF) relays in Rayleigh fading channels, in which the source broadcasts the signal to the relays in the first time slot and the relays simultaneously forward signals to the destination in the second time slot. Analytically studying the error performance of multiple dual-hop AF cooperative networks with maximal ratio combining (MRC) receivers at the destination and deriving closedform expressions has always been a difficult task. Considering an L-Relay nodes AF cooperative network in Rayleigh fading channels employing MRC, closed-form approximate expressions are derived for the bit error rate (BER) of a class of coherent modulation techniques that are easy to calculate, thus circumventing the computational inefficiency of the exact formulation. Exact results obtained using numerical integration are provided to validate the tightness of the proposed expressions. In addition, a slight modification for the amplification gain at the relay-node is proposed, which showed an improvement in the effective signal-to-noise ratio at the destination node

Performance of Selection Combining Diversity in Weibull Fading with Cochannel Interference

We evaluate the performance of selection combining (SC) diversity in cellular systems where binary phase-shift keying (BPSK) is employed and the desired signal as well as the cochannel interferers (CCIs) is subject to Weibull fading. A characteristic function-(CF-) based approach is followed to evaluate the performance in terms of the outage probability. Two selection criteria are adopted at the diversity receiver: maximum desired signal power and maximum output signal-to-interference ratio (SIR). We study the effect of the fading parameters of the desired and interfering signals, the number of diversity branches, as well as the number of interferers on the performance. Numerical results are presented and the validity of our expressions is verified via Monte Carlo simulations