ENHANCED PRACH FOR STANDALONE CONTENTION-BASED COMMUNICATIONS INCLUDING UNLICENSED SPECTRUM

摘要

Additional improvements to the design of enhanced physical random access channel (ePRACH) procedures are disclosed for communications systems having contention-based shared spectrum including unlicensed frequency bands. The additional improvements address the uncertainty of transmission in listen before talk (LBT) -based communications and cooperation with other radio access technologies competing for the same frequency spectrum. An extended clear channel Assessment over multiple subframes is performed by the UE, during which in particular the presence of channel reserving signals, such as CUBS, is monitored. In case of eCCA/CCA success,, the actual type 2 random access preamble is transmitted, before the subframe resync boundary, or else on the following subframe if does not fit anymore.