Method and apparatus for performing cell reselection for supporting efficiently hierachical cell structures

Abstract

A method for performing a cell reselection in a system comprised of a hierarchy of cells, wherein cells of one layer of the hierarchy have a size that differs from cells of another layer of the hierarchy. The method includes steps of (a) identifying to a user equipment a layer to which individual cells in a neighbor cell list are associated; (b) when performing neighbor cell measurements for reselection purposes, avoiding a measurement of cells in the list that are larger than a current serving cell unless a Cell Selection (S) parameter falls below a search threshold parameter (Ssearch), and is greater than zero; and (c), if S is less than or equal to zero, and no cell reselection to a better cell is in process, beginning a measurement of neighbor cells without regard for their hierarchical level. If the user equipment has made cell reselection to N different cells on the same hierarchical layer within a time Tmax, the user equipment initiates a reselection procedure for larger neighbor cells. This procedure accommodates user equipment that is moving at a relatively high speed through the cells. If the user equipment locates a larger cell, which fulfills cell reselection criteria Sn > 0 and Qn > Qs+Qoffsets,n+Qhyst for a period of time Treselection, cell reselection to the larger cell is made. Furthermore, if the user equipment performs a cell reselection to the larger cell, the user equipment does not attempt to reselect to a smaller cell within a time X, unless an immediate cell evaluation is triggered, wherein the time X can be pre-specified, or can be set by the network.

Description

Technical field [0001] The present invention generally relates to a wireless telephone system, and more specifically, the present invention relates to a cellular communication system in which a user equipment (UE) works in a cell and has the ability to perform cell selection and reselection operations. Background technique [0002] In a cellular communication system, a plurality of base stations or basic locations are provided, each of which has a surrounding coverage area (cell) in which mobile stations such as cellular phones, personal communication devices, packet data terminals, etc. are located jobs. The various devices are collectively referred to as user equipment (UE). When a UE can move relative to a cell, it can move from cell to cell. This requires a cell-to-cell handover process. One aspect of handover is that the UE generally has the ability to perform periodic (neighboring) cell signal measurement, measurement reporting, and, importantly, selection / reselection. An i...

AI Technical Summary

Problems solved by technology

The specification does not specify some priorities for measurements and cell reselection, but these priorities are not optimal in all respects

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