Performance analysis of discrete rate adaptation in OFDM under transceiver impairments

Practical orthogonal frequency division multiplexing (OFDM) based transmitters and receivers suffer from non linearity due to power amplifier at transmitter, and carrier frequency offset (CFO) and symbol timing offset (STO) at receiver. Link adaptation (LA) which matches power and data rate with instantaneous channel condition gets adversely affected due to these transmitter and receiver imperfections. In this paper we have analyzed the impact of these transceiver impairments on power adaptation and rate adaptation. It is seen from LA under transceiver impairments that less power can be pumped ultimately resulting into lesser data rate as compared with ideal transmitter and receiver. Further, it is also seen that for lower SNR region (poorer channel condition) the effect of non-ideality is less on average spectral efficiency (ASE) bits/sec/Hz, where as for higher SNR region (better channel condition) the impact of non-ideality is more, leading to degradation in ASE.