Impact of polar transmitter imperfections on UTRA LTE uplink performance

The polar transmitter is an alternative RF transmitter architecture solution to achieve a high-efficiency power amplifier. In this paper the impact of polar transmitter imperfections on the UTRA long term evolution (LTE) link level performance is investigated. The most common imperfections in a polar transmitter are modelled, such as timing delay alignment and power amplifier non-idealities. Our approach is to analyze the relation between error vector magnitude (EVM) and link performance loss due to each imperfection. The results obtained are based on LTE uplink parameter settings and show that the most severe polar transmitter problem in LTE uplink is the timing delay alignment, especially for higher order modulation and coding scheme. Results also show that the EVM is a good direct measure to estimate the link level performance loss for various imperfections in the anticipated EVM range. For 16 QAM rate 3/4, an SNR loss of approximately 0.5 dB can be estimated by an EVM value of 8%.