Evaluation of MIMO systems with respect to front‐end imperfections

Abstract

In multiuser multiple-input multiple-output (MIMO) systems the performance of joint detection and joint predistortion techniques highly depends on the quality of radio-frequency (RF) components. Therefore, the focus of this paper is on front-end imperfections. We demonstrate the influence of erroneous calibration (which is essential for downlink predistortion), phase noise and nonlinear amplifiers. For all issues we elaborate on the different disturbances that arise, analyse the impact on symbol estimation and evaluate system performance in terms of coded bit error ratio (BER). A general result for all examined front-end imperfections is that their influence increases with the number of spatially multiplexed data streams culminating in unacceptable performance degradation in fully loaded systems. Moreover, Wiener-based detection and predistortion reduces the degradation due to front-end imperfections in low SNR regimes compared to zero forcing

SABA: A Testbed for a Real-Time MIMO System

“…For notational convenience, the description of the permutation matrices is neglected at this point. Furthermore, note that joint detection in (7) and (8) only holds if the previously assumed covariance matrices R d and R n are temporally white. The whole single-carrier transmission scheme is depicted in Figure 5.…”

“…Compared to SISO systems, there are higher requirements for linearity, dynamic range, LO phase noise, and return loss suppression between antennas and transmitter outputs and receiver inputs, respectively. Some downlink predistortion schemes based on channel uplink matrix estimation require transceiver calibration in order to provide a reciprocal channel matrix [8]. The large number of adjustable parameters, for example, uplink, downlink, calibration mode, attenuation, antenna polarization, and the transceiver state monitoring demands an efficient controlling procedure.…”

“…Phase noise is introduced during the up-and down-conversion of the signal. It was shown by simulations in [8], that the main degradation is caused at the base station. However, when the phase noise at the base station is coherent, which means that the T/R branches share one common LO, less interference is introduced.…”

A Hybrid Framework for Incorporating Analog Front-End Effects in MIMO OFDM Design

“…frequency offset and phase noise [2]. When OFDM is further integrated with MIMO technology, the sensitivity to these impairments requires further investigation [3], [4], [5]. In [4] an OFDM-MIMO communication system and the impact of its front-end non-idealities have been investigated.…”