Assessing and Modeling the Effect of RF Impairments on UTRA LTE Uplink Performance

Radio Frequency Aspects

“…2 It has also been shown [10] that when EVM is less than 8%, it provides a good metric to predict the link level performance loss arising from transmitter impairments; for example, an EVM of 8% corresponds to an SNR loss of 0.5 dB with 16QAM rate 3/4.…”

“…The SINR requirement plus implementation margin is assumed to be 1.5 dB. The wanted signal is 7 dB above REFSENS at −88.2 dBm, so it can be calculated that the IM3 products must be 0.97 dB 10 Table 22.12.…”

“…For example, an OFDM-based systems are particularly sensitive to any distortion which may remove the orthogonality between the subcarriers, resulting in Inter-Carrier Interference (ICI), as discussed in Section 5.2.3. The RF impairments can have a non-negligible impact on BER, as shown for example in [10,18] and references therein, where some compensation algorithms are also discussed.…”

“…Often, a simple additive white Gaussian model can be considered to simplify the analysis of the impact of the RF impairments on link performance (see, for example, [10]). In fact the distortion generated by any non-linear device present for example in the downlink transmitter 13 can be modelled using Bussgang's theorem [19] as follows:…”

“…The received baseband signal, in the presence of only phase noise can be written as (22.19) where the transmitted signal is multiplied by a noisy carrier e jθ(t) . In [10] it is shown that the single-sideband phase noise power follows a Lorentzian spectrum [10,24]: (22.20) where f 3dB is the two-sided 3 dB bandwidth of phase noise. The power spectrum given in Equation (22.20) can be considered as an approximation to practical oscillator spectra.…”