Wireless user equipment for use in reducing cross cell interference

#The invention generally relates to wireless time division duplex (TDD) communication systems using code division multiple access (CDMA). In particular, the invention relates to reducing cross cell user equipment interference in such systems.

#FIG. 1 is an illustration of a wireless TDD/CDMA communication system 10. The communication system 10 has base stations 12l to 12n (12) which communicate with user equipments (UEs) 14l to 14n (14). Each base station 12 has an associated operational area or cell. The base station communicates with UEs 14 in its cell.

#In CDMA communication systems, multiple communications are sent over the same frequency spectrum. These communications are distinguished by their channelization codes. To more efficiently use the frequency spectrum, TDD/CDMA communication systems use repeating frames divided into timeslots, such as fifteen timeslots, for communication. In TDD, each cells' timeslots are used solely for either the uplink or downlink at a time. A communication sent in such a system has one or multiple associated code(s) or timeslot(s) assigned to it. The use of one code in one timeslot with spreading factor of sixteen is referred to as a resource unit.

#FIG. 1 is an illustration of a wireless TDD/CDMA communication system.

#FIG. 2 is an illustration of cross interference between UEs.

#FIG. 3 is a flow chart for UE cross cell interference reduction.

#Although the UE cross cell interference reduction is explained in the context of unsectorized cells, the approach is extendable to any UE operating area division, such as sectors of a cell. In such an extension, each operating area, such as a sector, is treated as a separate cell in the analysis.

#FIG. 3 is a flow chart for UE cross cell interference reduction. For each cell, the cell's base station 12 measures the interference level in each timeslot, such as by using ISCP, step 22. The measured interference in each timeslot is compared to a threshold. If the measured interference in a timeslot exceeds the threshold, that timeslot is eliminated as a timeslot for any additional uplink communications in that cell, step 23. The threshold level is typically set by the system operator.

#Each UE 14 measures the interference level in each timeslot, such as by ISCP, step 24. To determine available downlink timeslots for a particular UE 14, the measured interference in each timeslot is compared to a threshold. The threshold level is typically set by the system operator. If the measured interference exceeds the threshold, that timeslot is eliminated for the downlink for that particular UE 14, step 25.