Unsuitable cell exclusion in wireless communication systems
AssigneeInterDigital Technology Corporation
InventorsAlpaslan Demir, Donald M. Grieco, John W. Haim, Andrew F. Bednarz
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Abstract
A method for performing initial cell search in wireless communication system wherein unsuitable cells includes searching stored frequencies exhaustively and initial frequencies non-exhaustively. Initial frequencies may be searched exhaustively in certain circumstances. When performing exhaustive initial cell searches, primary synchronization codes that lead to unsuitable cells are excluded from subsequent initial cell searches performed on the same frequency.
Claims6
A method for performing initial cell search, the method comprising:
- performing an exhaustive initial cell search on stored frequencies wherein the exhaustive initial cell search includes:
- maintaining a list of any chin-offset locations that lead to unsuitable cells characterized as step 1 of the initial cell search, wherein step 1 of the initial cell search includes a wireless transmit/receive unit (WTRU) looking for a primary synchronization code (PSC) correlator peak location with the highest power;
- generating a mask for said chip-offset locations, characterized as step 2 of the initial cell search, so that subsequent step 1 of the initial cell search will not detect any PSCs in the masked chip-offset locations;
- performing a non-exhaustive initial cell search on initial frequencies on a condition that no cell is found from the exhaustive initial cell search on stored frequencies;
- and
- performing an exhaustive initial cell search on initial frequencies on a condition that no cell is found or an unsuitable cell is detected from the non-exhaustive initial cell search on initial frequencies.
A method for performing an exhaustive initial cell search, the method comprising the steps of:
- performing a step 1 of an initial cell search, wherein any rejected chip-offsets are masked so that any primary synchronization codes (PSCs) located within the rejected chip-offsets are excluded, wherein step 1 of the initial cell search includes a wireless transmit/receive unit (WTRU) looking for a PSC correlator peak location with the highest power;
- decreasing the gain setting where no detection is made while performing step 1 initial cell search;
- running a step 2 of the initial cell search where there is a detection while performing step 1 of initial cell search, wherein step 2 of the initial cell search includes determining the timeslot offset of the detected PSC location and the code group using secondary synchronization codes (SSCs) transmitted along with the detected PSC;
- running a step 3 of the initial cell search where there is a detection while performing step 2 of initial cell search, wherein step 3 of the initial cell search includes determining the scrambling code and unique midamble base identification number;
- reading the broadcast channel of a cell to obtain the public land mobile network identifier (PLMN ID) detected while performing step 3 of the initial cell search;
- determining whether the detected cell is unsuitable based on the PLMN ID of the detected cell;
- and
- adding to a rejected chip-offset list, the chip-offset of the detected PSC wherein the detected PSC led to the detected cell and the detected cell ID is unsuitable.
Dependencies are inferred from the claim text.