Abstract-Physical transceivers have hardware impairments that create distortions which degrade the performance of communication systems. The vast majority of technical contributions in the area of relaying neglect hardware impairments and, thus, assumes ideal hardware. Such approximations make sense in low-rate systems, but can lead to very misleading results when analyzing future high-rate systems. This paper quantifies the impact of hardware impairments on dual-hop relaying, for both amplify-and-forward and decode-and-forward protocols. The outage probability (OP) in these practical scenarios is a function of the effective end-to-end signal-to-noise-and-distortion ratio (SNDR). This paper derives new closed-form expressions for the exact and asymptotic OPs, accounting for hardware impairments at the source, relay, and destination. A similar analysis for the ergodic capacity is also pursued, resulting in new upper bounds. We assume that both hops are subject to independent but non-identically distributed Nakagami-m fading. This paper validates that the performance loss is small at low rates, but otherwise can be very substantial. In particular, it is proved that for high signal-to-noise ratio (SNR), the end-toend SNDR converges to a deterministic constant, coined the SNDR ceiling, which is inversely proportional to the level of impairments. This stands in contrast to the ideal hardware case in which the end-to-end SNDR grows without bound in the high-SNR regime. Finally, we provide fundamental design guidelines for selecting hardware that satisfies the requirements of a practical relaying system. Index Terms-Amplify-and-forward, decode-and-forward, dual-hop relaying, ergodic capacity, Nakagami-m fading, outage probability, transceiver hardware impairments.
Moreover, Björnson et al. quantified the impact of additive hardware distortions on the outage probability and suggested design guidelines for optimal performance of dual-hop relaying systems REF .
A New Look at Dual-Hop Relaying: Performance Limits with Hardware Impairments
IEEE Transactions on Communications, vol. 61, no. 11, pp. 4512-4525, November 2013
Computer Science Mathematics