Interference control, SINR optimization and signaling enhancements to improve the performance of OTDOA measurements
View Patent ↗A wireless terminal receives signaling information, pertaining to a reference signal transmission in at least one specifically designated sub frame, the signaling information including a list, the list including base station identities. The terminal determines, from at least one of the base station identities in the list, the time-frequency resources associated with a reference signal transmission intended for observed time difference of arrival (OTDOA) measurements from a transmitting base station associated with said one base station identity. The time of arrival of a transmission from the transmitting base station, relative to reference timing, is measured. The wireless terminal can receive a command from a serving cell to start performing inter-frequency OTDOA measurement on a frequency layer containing reference signals, the frequency layer distinct from the serving frequency layer, the serving frequency layer not containing positioning reference signals. The wireless terminal can perform OTDOA measurements subsequent to the reception of the command on a carrier frequency different from the serving cell carrier frequency. A base station transmitter can jointly schedule a reference signal transmission from a plurality of base station transmitters for the purpose of OTD estimation enhancement, and transmit identical reference signals from the plurality of base station transmitters, the reference signals being identical both in the signal sequence and time-frequency resources used for transmission.
1. A method in a wireless terminal including;
receiving by the wireless terminal from a first base station signaling information, pertaining to a reference signal transmission in at least one specifically designated sub frame, the signaling information including a list, the list including for at least one other base station information including an identity and a reference signal offset for the at least one other base station reference signal;
determining by the wireless terminal, from the at least one other base station information including the reference signal offset, a window for detecting the time-frequency resources associated with a reference signal transmission intended for observed time difference of arrival (OTDOA) measurements from the at least one other base station; and
measuring time of arrival of a transmission received during the window from the at least one other base station relative to a reference timing.
2. The method of claim 1 further including receiving signaling information on reference signal patterns corresponding to a serving cell and neighbor cells.
3. The method of claim 1 further including receiving a neighbor cell list together with the relationship between a base station identity of a neighbor cell and a measurement pattern.
4. The method of claim 1 wherein the measurement pattern follows a predetermined time-frequency re-use pattern.
5. The method of claim 1 further including receiving frequency layer information corresponding to said serving cell base station and at least one neighbor cell base station.
6. The method of claim 1 further including receiving a minimum measurement bandwidth associated with reference signal transmissions for the purpose of OTDOA measurements applicable to neighbor cells.
7. The method of claim 1 further including receiving deployment type information pertaining to whether the OTDOA sub frame transmissions from a serving cell and neighbor cells are aligned, partially aligned or unsynchronized, the deployment type information directly indicating one of aligned, partially aligned, unsynchronized, or search window size.
8. The method of claim 1 further including receiving system timing of a neighbor cell relative to a serving cell, the system timing corresponding to a system frame number time difference for each neighbor cell relative to said serving cell.
9. The method of claim 1 further including receiving an indication to use cell-specific reference symbols (CRS) for OTDOA measurements; and receiving information pertaining to at least one sub frame over which the wireless terminal is expected to perform neighbor cell OTDOA measurements.
10. The method of claim 1 further including
receiving subframe-subframe timing difference for neighbor cells relative to serving cell.
11. The method of claim 1 wherein the base station identity is one of at least physical cell identity (PCID) or site identity.
12. A method in a wireless terminal including
receiving a command from a serving cell to start performing inter-frequency OTDOA measurement on an other frequency layer containing reference signals, the other frequency layer distinct from a frequency layer of the serving cell;
receiving by the wireless terminal an offset between a reference signal from the serving cell and a reference signal from a neighbor cell; and
performing by the wireless terminal OTDOA measurements subsequent to the reception of the command, the wireless terminal searching for the reference signal from the neighbor cell on the distinct carrier frequency within a window determined at least in part from the offset.
13. The method of claim 12 further including receiving information regarding times when transmission gaps from the serving cell are enabled.
14. The method of claim 12 further including receiving information regarding times when transmission gaps from the serving cell are disabled.