2013 Poster Sessions : Null Space Learning In MIMO Cooperative Cellular Networks Using Interference Level Feedback

Student Name : Alexandros Manolakos
Advisor : Andrea Goldsmith
Research Areas: Information Systems
Cooperative Multi-Point (CoMP) is a technology for improved spectrum utilization where a group of neighboring Base Stations (BSs) coordinate their transmission to form a virtual BS. However, the performance gain is severely degraded due to Out of Group interference (OGI). The major challenge in designing an Interference Suppression (IS) mechanism between different Base Station Groups (BSG) is to obtain and exchange Channel State Information (CSI) between the groups. This difficulty is due to network limited-capacity backhaul, synchronization problems, transmission latency, signaling overhead and the desire to not burden battery-based User Equipment (UE) with extra computations. In this paper, we propose simple OGI IS schemes that utilizes existing network information, i.e. the interference levels at the UE. In the proposed schemes, the interfering BSG transmits a sequence of learning signals which inflict low interference on a UE of a neighboring BSG. The schemes utilize the fact that each UE normally measures its interference levels and feed them back to its serving BSs. Then, the serving BSG distributes this information to the interfering BSG, from which it learns the null space of the interfering channel. The proposed algorithms do not affect the transmission protocol between the UE and the serving BSG, and do not add any signaling to the control channel between them. Each UE communicates only with its serving BSG and treats the learning signals of interfering BSG as noise.

Alexandros Manolakos is currently pursuing a Ph.D. degree in the Electrical Engineering department at Stanford University under the supervision of Prof. Andrea Goldsmith. In June 2010, he received with honors a Diploma Degree in Electrical and Computer Engineering from the National Technical University of Athens in Greece and in June 2012 a Master of Science in Electrical Engineering from Stanford University. In 2012, as the team leader of the "Underlay MIMO" Team, together with Dr. Yair Noam and Prof. Goldsmith, he won the 3rd place in the Interdigital's Innovation Challenge (I2C). Also, the same year, he was awarded the Roberto Padovani Scholarship award for stellar internship performance in Corporate R&D, Qualcomm, San Diego.