Unified Tensor Modeling for Blind Receivers in Multiuser Uplink Cooperative Systems

In this letter, we present new blind receivers for uplink multiuser cooperative diversity systems. Considering amplify-and-forward (AF), fixed decode-and-forward (FDF), and selective decode-and-forward (SDF) relaying protocols, the proposed receivers exploits a unified formulation of the received signal as a CANDECOMP/PARAFAC (CP) model with dimensions
$receive\ antenna\times cooperative\ branch\times symbol\ period$
. Under the assumption that channel state information (CSI) is not available neither at the relays nor at the base station, the proposed receiver jointly and blindly estimates the transmitted symbols and channel parameters. In addition to avoiding the use of pilots symbols, the CP-based receiver can operate with less base station antennas than users or, alternatively, with a single relay per user.