don't know why they waited 3 months since the agreement to arbitrate, but at least it started.
Pursuant to their agreement, on April 9, 2014, InterDigital and Huawei initiated an arbitration with the International Court of Arbitration of the International Chamber of Commerce (ICC) jointly seeking a determination by an arbitral tribunal of FRAND royalty terms and conditions to be included in a binding worldwide patent license agreement to take effect upon issuance of the arbitration award. This arbitration is expected to be completed by early 2015.