Picocell base station for wireless telecommunications providing radio coverage lobes, and a method of identifying which subset of the lobes covers a user terminal

A method, in a base station for wireless telecommunications having multiple directional antenna elements each providing a corresponding radio coverage lobe, of identifying which subset of the lobes covers a user terminal,

• wherein the base station is a picocell base station and the method comprising the steps of:
• positioning a user terminal within the coverage area of the base station,
• selecting a subset of the lobes,
• the base station for a period applying an adjusted pilot signal power in respect of the selected subset of the lobes,
• the user terminal detecting received pilot signal power and reporting to the base station information dependent upon the detected signal power,
• the base station determining dependent upon said information whether or not the user terminal is located in the selected subset of lobes, in which further steps are undertaken of:
• selecting a sub-group of the subset of the lobes,
• the base station for a period applying an adjusted pilot signal power in respect of the selected sub-group,
• the user terminal detecting received pilot signal power and reporting to the base station information dependent upon the detected signal power,
• the base station determining dependent upon said information whether or not the user terminal is located in the selected sub-group,
• in which the base station for a period increases pilot signal power in respect of the selected subset of the lobes, then increases signal power for a period in respect of the other subset of the lobes,
• the method including the user terminal detecting received pilot signal power and reporting information to the base station as to which of the subsets provides the greater increase in the detected signal power,
• the base station determining dependent upon said information in which subset of lobes the user terminal is located.