Interference measurement in heterogeneous networks

摘要

In a heterogeneous network based on LTE, the random access, RA, procedure triggered in a macrocell produces transmissions from a UE (20) on the physical random access channel, PRACH, which a picocell eNB (12) can attempt to make measurements of for interference coordination purposes over the X2 interface between the macro eNB (10) and the pico eNB (12). 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 (10) to the UE (20), such as the RA preamble it uses and the C-RNTI it is assigned during the procedure. Interpreting these new meanings allows the UE (20) to temporarily re-configure its PRACH transmissions so as to be useful to the pico eNB's (12) 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.

主权项

1. A wireless communication system comprising a terminal, a first base station and a second base station,
the terminal arranged to transmit a first signal to the first base station in accordance with a procedure, the first base station arranged to configure the terminal with one or more characteristics of the procedure including any of:
a preamble carried by the first signal;a particular value of an identifier in a second signal transmitted by the first base station in response to the first signal;timing of the second signal with respect to the first signal; andwhether the timing of the transmission of the first signal is determined by the terminal or by the first base station; the first base station arranged to provide information about the procedure to the second base station; and the second base station arranged to monitor signals transmitted from the terminal on the basis of the information; wherein: the one or more characteristics are predefined as being capable of facilitating interference coordination between the first and second base stations by indicating at least one further characteristic of the procedure which makes the first signal suitable for measurement by the second base station; and the first base station is further arranged to confirm actual use of the one or more characteristics for facilitating interference coordination by providing a notification of such use to the terminal.