Coordinated Multi-Point (CoMP): Unresolved problems

I have blogged about CoMP in quite some detail in the past. Someone recently pointed out an interesting video from Fraunhofer Heinrich Hertz Institut which is embedded below:

CoMP may be not as practical as we may think. One of the things pointed out by Dr. Ariela Zeira, InterDigital's Vice-President of Advanced Air Interfaces in the LTE World Summit was that there exists a gap between the theoretical and the practical gains of CoMP.

She went on to suggest the following as way forward for the Coordinated Multipoint acceptance in future:

• Address root causes of gaps between academia and current feedback schemes
• Need for improved Channel State Information (CSI) feedback resolution
• Need for improved frequency domain precoding granularity
• Apply CoMP where most needed and/or theoretical gains can be approached
• Heterogeneous networks
• Interference problem is more severe than in macro-only deployment
• Especially for Femto Closed Subscriber Group and Pico Cells employing large cell extension
• Lower delay spread and low mobility can be expected in Femto and Pico cells and reduce performance loss from feedback impairments
• Relay Backhaul Channel (RBC)
• More accurate CSI feedback from stationary relay station is possible enabling advanced non-linear precoding schemes.
• High rank MIMO transmission will not be effective due to higher probability of Line of Sight (LOS) channel from Macro to Relay

CoMP is still probably the most promising spectral efficiency solution but need to focus on closing the gap between gains predicted by theory and those achievable with current LTE Release 8 Feedback Schemes