A Conflict-Free Radio Network Temporary Identity Allocation Algorithm for User Equipments

摘要

In order to distinguish among the messages transmitting to different User Equipments (UEs), each UE will be allocated one or more Radio Network Temporary Identifiers (RNTIs) by the eNodeB in Long Term Evolution (LTE) releases and 5G Release 15. The allocated RNTI of a UE is used to map the position of its UE-specific Physical Downlink Control Channel Search Spaces (PDCCH SSs) in systems and the RNTIs of multiple UEs mapping to the same UE-specific PDCCH SS in a subframe may cause a RNTI allocation conflict. Reasonable RNTIs and RNTI allocation schemes can reduce RNTI allocation conflicts and increase the Control Channel Element (CCE) utilization, which improves the online UE capacity of systems. The Conflict-Free RNTI Allocation Algorithm (CFRAA) that calculates the RNTIs for UEs reasonably to avoid RNTI allocation conflicts was proposed by us. It contains two calculations of RNTI-to-SS mapping and SS-to-RNTI mapping owning high computational complexity. We further proposed the Simple Method of RNTI-to-SS Mapping (SMRSM) and the Reverse Mapping Method Based on Inverse Element (RMMBIE) respectively to simplify the two calculations. With the help of the two methods, the CFRAA reduces the time consumption dramatically up to 86.1% and improves the CCE utilization rate by 15.3% compared with the common random allocation scheme, continuous allocation scheme and interval allocation scheme through simulation.