When Carrier Aggregation and cross-carrier scheduling are applied in LTE-Advanced system, UE may support multiple Component Carriers (CC) and control information on one CC can allocate radio resource on another CC. Search space of all CCs and control information is only transmitted from a chosen CC. In this case, if search spaces of different CCs are not properly defined, high blocking probability of control information will be very harmful to system performance.
My Question is: What is the cause of this blocking, is it deficiency of control channel elements to served, scheduled UE or what?
My guess is not but I have no proof of this. Can any expert help?
For now, I assume either self-overlapping or high mutual over-lapping of the UEs' search spaces as the likely cause of blocking.
UE point of view, one CC would be primary CC to decode PDCCHs of configured CCs. However, eNB point of view or network point of view, eNB can assign different primary CC to indivisual UEs. That means, one CC does not need to transmit all PDCCHs of all UEs. eNB scheduler can control the load of PDCCH between CCs. Then, such high blocking probability may not occur if the operator uses good scheduling algorithm for carrier aggregation.
The main responsible guys behind Blocking users are Available CCEs and the Schedular one design to get the user fit into this If the hash function gives the indices which are already occupied then user can't get scheduled resulting in getting blocked. I hope the mentioned point makes sense to understand the reason for blocking users. Kindly refer to this to understand clearly.
https://ieeexplore.ieee.org/document/7382423
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