Effects of RF Impairments in Communications over Cascaded Fading Channels



Direct-conversion architectures can offer highly integrated low-cost hardware solutions to communication transceivers. However, it has been demonstrated that radio frequency (RF) impairments such as amplifier nonlinearities, phase noise and in-phase/quadrature-phase imbalances (IQI) can lead to a severe degradation in the performance of such systems. Motivated by this, the present work is devoted to the quantification and evaluation of the effects of RF IQI on wireless communications in the context of cascaded fading channels for both single-carrier and multi-carrier systems. To this end, closed form expressions are firstly derived for the outage probability (OP) over N*Nakagami−m channels for the cases of ideal transmitter (TX) and receiver (RX), ideal TX and IQI RX, IQI TX and ideal RX, and joint TX/RX IQI. The offered expressions along with several deduced corresponding special cases are subsequently employed in the context of vehicular-to- vehicular (V2V) communications to justify their importance and practical usefulness in the context of emerging communication systems. We demonstrate that considering non-ideal RF front- ends at the TX and/or RX, introduces non-negligible errors in the OP performance that can exceed 20% in several communication scenarios. We further demonstrate that the effects by cascaded multipath fading conditions are particularly detrimental, as they typically result in considerable performance losses of around or over an order of magnitude.

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