The EVM is supposed to be measured in an interference-free situation, so that you are only measuring the impact of hardware impairments. If you don’t have any hardware impairments, the EVM should only be determined by the receiver noise.

I don’t know how you are carrying out your simulations, but you can categorize the different components of the received signal and draw a bar diagram to understand the relative size of the different components.

Thank you very much, Prof. Emil Björnson. Yes, I do not have hardware impairments, so it could be that EVM is only dependent on thermal noise. Although I have a follow-up question:

1) If I have two users close by, then I still would get a noisy constellation and high EVM. Hence, I was of the opinion that interference indeed has some effect on the EVM.

2) Could you please explain what did you mean by the components of the received signal?

Your question is very interesting, thank you for taking me into account.

The calculated EVM is sensitive to any noise and signal distortions that are reflected in its amplitude and phase components. As a rule, when calculating the EVM, systematic errors (for example, the shift of the constant component of current or voltage, phase, I/Q or amplitude imbalance, etc.) are not taken into account and require preliminary correction. But such correction is not full. On the other hand, a very important role has the distance between sources of signals in angle coordinates. You can calculate the Lower Cramer-Rao Bound to an estimation of this impact. Of course, need to take into account jammers and multiple path and mirrors of signals

Dear Gopika Sudhakaran , Adding to the respected colleagues:

When you draw the constellation at the receiver then it will be affected by by all impairments in the system. It will be impaired any any communication parameter affecting the causing amplitude and phase distortion in addition to the added noise and interference signals.

In the transmitter the major EVM comes from the nonlinear distortion in the amplifier. Then it comes the signal distortion because of the channel impairments. And finally comes the additional added signal which is the thermal noise of the receiver and interference from the nearby sources.

Best wishes

EVM is basically sought for the distortion associated by the power amplifier of the transmitter. However, it can be extended to the receiver and whole transmission system.

Best Wishes

If you want to model a multi-user system in which its transceiver suffer from radio frequency (RF) imperfections, you can write the baseband equivalent received signal at the i-th user equipment as

y_i = \sum_{n=1}^N h_{i,n} \left(s_n + w^t_n\right) + w^r_i + z_i,

where

N is the number of UEs

h_{i,n} is the channel between the i transmitter and n receiver

w^t_i is a zero-mean complex Gaussian process with variance (k^t_n)^2 P_s that models the distortion noise at the n-th transmitter due to hardware imperfections,

w^r_i is a zero-mean complex Gaussian process with variance (\left|\sum_{n=1}^N h_{i,n}\right| k^r_i)^2 P_s that models the distortion noise at the i-th receiver due to hardware imperfections

and

z_i is the additive white Gaussian noise.

The parameters k^t_n and k^r_i are respectively the EVM at the n-th transmitter and i-th receiver.

For more information, please refer to the following papers:

Preprint Analytical Performance Evaluation of Beamforming Under Trans...

Article Analytical Performance Assessment of THz Wireless Systems

Article Physical Layer Security in the Presence of Interference

Article Energy Detection in Full-Duplex Systems With Residual RF Imp...

Article Spectrum Sensing in Full-Duplex Cognitive Radio Networks Und...

Article Energy Detection Spectrum Sensing Under RF Imperfections

Article Spectrum Sensing With Multiple Primary Users Over Fading Channels

Article Error Analysis of Mixed THz-RF Wireless Systems

Article How Much do Hardware Imperfections Affect the Performance of...

Preprint Cascaded Composite Turbulence and Misalignment: Statistical ...