Simple Methods for Estimating Required SNR in Dual-Polarized MIMO Systems Under Limited XPD

This paper presents simple semi-analytical methods for estimating the required carrier-to-noise ratio (CNR) in multi-input multi-output (MIMO) broadcasting systems. The estimates are derived according to cross-polarization discrimination (XPD) level of the transmission channel, thereby evaluating the impact of cross-polarization interference. The proposed models convert known single-input single-output (SISO) system performance, e.g., CNR threshold measurements in ATSC A/327 [AnnexA,1], into the CNR required in MIMO transmission. Two classes of estimation are developed: one assuming perfect channel knowledge (Class P), and the other accounting for channel estimation errors and pilot boosting (Class E). In addition to the conventional single-layer configuration, estimations under layered division multiplexing (LDM) configurations are also addressed, where every layer is assumed to use MIMO. Closed-form expressions are provided for both layered and non-layered MIMO scenarios. The models offer a lightweight alternative to full-system simulations, enabling early-stage design evaluation and practical system planning in cross-polarized environments.