On uplink-downlink sum-MSE duality of multi-hop MIMO relay channel
Ali Çağatay Cırık, Muhammad R. A. Khandaker, Yue Rong, Yingbo Hua · 2014
The uplink and downlink sum mean-squared error (MSE) duality for multi-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relay channels is established, which is a generalization of several sum-MSE duality results. Unlike the previous results that prove the duality by computing the MSEs for each stream directly, we introduce an interesting perspective to the relation of the uplink-downlink duality based on the Karush-Kuhn-Tucker (KKT) conditions associated with uplink and downlink transceiver design optimization problems.