Interference measurement in heterogeneous networks

Abstract

In a heterogeneous network based on LTE, the random access, RA, procedure triggered in a macrocell produces transmissions from a UE () on the physical random access channel, PRACH, which a picocell eNB () can attempt to make measurements of for interference coordination purposes over the X2 interface between the macro eNB () and the pico eNB (). By reconfiguring the UE's behavior during principally the contention-free RA procedure, its transmissions on PRACH are made different to the default such as to be suitable for heterogeneous network interference measurements. This is done by assigning new meanings to certain of the characteristic parameters provided by the macro eNB () to the UE (), such as the RA preamble it uses and the C-RNTI it is assigned during the procedure. Interpreting these new meanings allows the UE () to temporarily re-configure its PRACH transmissions so as to be useful to the pico eNB's () interference measurement needs without disrupting the UE's existing configuration within the macrocell, and without the UE needing to know the purpose of its transmissions.