I've been looking for a technical explanation as well. The best I've found so far are a host of the patents ostensibly associated with pCell implementation [1], [2], [3], etc.

[1] System and method for DIDO precoding interpolation in multicarrier systems https://www.google.com/patents/US8571086

[2] System and method for adjusting DIDO interference cancellation based on signal strength measurements http://www.google.com/patents/US20110002371

[3] Systems and methods to coordinate transmissions in distributed wireless systems via user clustering http://www.google.com/patents/US20110002371