Network-Assisted Widely Linear Receivers for LTE

In order to improve cell-edge performance in LTE downlink, several techniques (e.g., Coordinated multi-point transmission) are investigated in the literature which rely on coordination of transmitting nodes without further optimization of receiver algorithms. This paper introduces a new coordination method where the radio network coordinates its transmitted modulation alphabet to assist a widely-linear MMSE (WL-MMSE) receiver to mitigate more effectively the received interference. Assistance from the network ensures that a WL-MMSE receiver is exposed to PAM-type interference which is afterwards mitigated. The technique exploits the fact that complex-valued baseband received samples are split in in-phase (I) and quadrature-phase (Q) parts. These I-Q samples are filtered independently using widely-linear processing. Consequently, better signal estimation is achieved under conditions of PAM-type interference as it is shown by the available literature in widely linear filtering. Finally, simulation results for the introduced scheme show up to 88% coverage gain.