What is phase noise in OFDM?
MIMO OFDM receivers are very sensitive to the phase noise coming from the difference between the carrier frequency and the local oscillator (LO). High order modulations such as 256 QAM are also severely affected by phase noise. Phase noise is typically modeled as a multiplicative noise.
What is common phase error OFDM?
The effect of PHN can be split into two: the rotation of all the sub carriers by a certain angle called the common phase error and the leakage of neighboring sub carriers resulting in inter carrier interference (ICI). CPE is the average of the PHN sequence spanning an OFDM symbol.
What is the main objective of time synchronization for OFDM?
When using OFDM it is necessary to ensure that the synchronisation for both timing and frequency is accurate. By ensuring accurate synchronisation, it is possible to perform the optimum demodulation of the signal. Any misalignment causes the receiver to start to pick up the unwanted interference signals.
What issue is caused by phase noise in OFDM system?
One drawback of OFDM is its sensitivity to phase noise. It has been shown that even small phase noise leads to significant performance loss of OFDM. Therefore, phase noise effects on OFDM systems need to be analyzed and methods be provided to its mitigation.
What is common phase?
the phase noise is resolved into two components, namely the Common Phase. Error (CPE), which affects all the subchannels equally and the Inter Car- rier Interference (ICI), which is caused by the loss of orthogonality of the. subcarriers.
How is OFDM calculated?
Thus the bandwidth of the OFDM baseband signal is N/2*delta_f,delta_f is the sub-carrier frequency spacing. The sub-carrier frequency spacing delta_f =1/Ts= 1/(Td * N), Ts is the OFDM symbol duration,Td is the sampling symbol duration and equal to the smapling time interval。 Thus Td=1/fs, fs is the DAC sampling rate.