BER Evaluation of Linear Detectors in Massive MIMO Systems Under Imperfect Channel Estimation Effects

• Published in: IEEE access Vol. 7; pp. 174482 - 174494
• Main Authors: Altamirano, Carlos Daniel, Minango, Juan, Mora, Henry Carvajal, De Almeida, Celso
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antennas; BER; Bit error rate; Channel estimation; Detectors; Error analysis; Fading channels; imperfect channel estimation; massive MIMO; maximal-ratio combining; MIMO (control systems); MIMO communication; minimum-mean-square error; Quadrature amplitude modulation; Sensors; Signal to noise ratio; Symbols; Tightness; Wireless communications; zero-forcing
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2019.2956828

New perspectives for wireless communications have brought new techniques, such as a very large number of antennas at a base station (BS) serving multiple user terminals (UTs) with a single antenna each, known as massive MIMO (M-MIMO). M-MIMO linear detectors, such as maximal-ratio combining (MRC), zero-forcing (ZF) or minimum-mean-square error (MMSE) can achieve excellent performance with low complexity due to the channel hardening property. However, imperfect channel estimation produces a penalty in the performance. An average bit error rate (BER) performance analysis over time-invariant channel is presented for M-MIMO systems under imperfect channel estimation in contrast with most of M-MIMO literature that uses the ergodic capacity approach. Closed-form expressions and bounds to evaluate the average BER are derived for MRC, ZF and MMSE detectors in a unicellular environment considering M-QAM modulation. Furthermore, an expression to evaluate the normalized signal-to-noise ratio (E b /N 0 ) penalty due to the imperfect channel estimation is presented. Montecarlo numerical simulations are used to verify the tightness of the derived equations which are a function of the number of BS antennas, number of users, coherence time interval, number of pilot symbols and the E b /N 0 of pilot and data symbols used for channel estimation and data detection.