Interference-free Transmission for the Cellular Downlink in LTE-Advanced

Abstract

Collaborative MIMO is shown with two base stations per forming coherent data transmission to two terminals in the downlink while the interference is cancelled crosswise. The demonstration illustrates the effect of both advanced receiver algorithms using optimum combining and advanced transmitter optimization using distributed precoding. The downlink transmission can be demonstrated over the air as well as using a MIMO channel emulator.

Technical Background

• Multi-cell channel estimation is done by cell-specific pilots sent from each base station
• Channel state information (CSI) feedback is provided over the air to the serving base station
• Base stations jointly precode messages for both users
• Crosswise interstream interference vanishes due to channel matched spatial precoding
  
  

Benefits

• Significantly reduced interference between cells
• Enhanced performance for cell-edge users fading algorithms
• Better spatial reuse of resources
• Distributed approach can be easily introduced into 3GPP-LTE transmission chain

Acknowledgments

This work was supported in part by the Federal Ministry Germany of Educational and Research (BMBF) in the projects ScaleNet and EASY-C.

References

• L. Thiele, T. Wirth, M. Schellmann, Y. Hadisusanto, and V. Jungnickel, "MU-MIMO with Localized Downlink Base Station Cooperation and Downtilted Antennas", IEEE International Workshop on LTE Evolution, Dresden, Germany, June 2009.
• L. Thiele, T. Wirth, T. Haustein, V. Jungnickel, E. Schulz, and W. Zirwas,
  "A Unified Feedback Scheme for Distributed Interference Management in Cellular Systems: Benefits and Challenges for Real-Time Implementation", 17th Euopean Signal Processing Conference (EUSIPCO2009), Glasgow, Scotland, Aug. 2009, invited.
• V. Jungnickel, L. Thiele, M. Schellmann, T. Wirth, W. Zirwas, T. Haustein, and E. Schulz, "Implementation Concepts for Distributed Cooperative Transmission", 42nd Asilomar Conference on Signals, Systems and Computers, Monterey, USA, Oct. 2008.
• L. Thiele, M. Schellmann, T. Wirth, and V. Jungnickel, "Cooperative Multi-User MIMO based on Reduced Feedback in Downlink OFDM Systems", 42nd Asilomar Conference on Signals, Systems and Computers, Monterey, USA, Oct. 2008.