Beamforming OFDM Performance Under Joint Phase Noise and I/Q Imbalance

Uplink Multiuser MIMO‐OFDM System in the Presence of Phase Noises, Power Imbalance, and Correlation

“…Note that (1) only holds approximately since the PN in the CP and the end of the time-domain OFDM symbol are different. Nevertheless, it is a good approximation [11,15,17]. By separating the CPE and ICI terms (1) can be rewritten as…”

“…For simplicity, we assume the Wiener PN model for the free-running oscillator, whose discrete-time expression is given as follows [11,[13][14][15]:…”

“…Unfortunately, MIMO-OFDM systems are sensitive to oscillator phase noises [11][12][13][14][15][16][17][18][19][20][21][22][23], which cause common phase error (CPE) and intercarrier interference (ICI). While the CPE is a common phase rotation for all the subcarriers (of one OFDM symbol), the ICI represents the interferences caused by nonorthogonal subcarriers.…”

“…While the CPE is a common phase rotation for all the subcarriers (of one OFDM symbol), the ICI represents the interferences caused by nonorthogonal subcarriers. The PN effect on single-user MIMO-OFDM (SU-MIMO-OFDM) systems has been well studied in the literature [11][12][13][14][15][16][17][18][19]. Most of the works assume a common oscillator for all the antennas at the transceiver [11][12][13][14][15][16], whereas the case of an independent oscillator for each antenna has been studied in [17][18][19].…”

“…Specifically, we derive a closed-form expression of the mean square error (MSE) performance of the uplink MU-MIMO-OFDM system with and without power imbalance and correlation, assuming the CPEs of different PNs can be perfectly estimated. (Given the fact that the CPE is just the time average of the PN over one OFDM symbol, the CPE can usually be estimated accurately [11,14,15]. The effect of imperfect CPE estimation is included in simulations.)…”