Chapter 7: Joint Spatial Division and Multiplexing (JSDM)

Learning Objectives

• Understand how spatial correlation structure enables user grouping by angle-of-arrival
• Master the two-stage JSDM precoding architecture: pre-beamforming plus inner MU-MIMO precoder
• Derive the dimensionality reduction from $N_t$ to $r_g$ per group and quantify the CSI overhead savings
• Analyze sum-rate performance and asymptotic optimality of JSDM in the large-array regime
• Connect JSDM to practical FDD massive MIMO and the 5G NR Type II codebook