Patent ID: 7596112

Claim:
A method for use in facilitating rate compatible dirty paper coding (DPC) for a plurality of wireless transmit/receive units (WTRUs) in a broadcast channel, the method comprising: computing an achievable rate region based on a total transmit power limit and a channel gain of each WTRU; selecting an order of DPC among the WTRUs; selecting a rate set for use in transmitting to the WTRUs, said rate set being within the achievable rate region; and performing DPC on a plurality of data streams intended for the WTRUs, wherein the performing DPC step is implemented via nested lattice coding, and the performing DPC step further comprises: establishing a fine lattice; defining a group of nested sub-lattices of the fine lattice, wherein each sub-lattice represents a nesting ratio associated with an achievable data rate; selecting a least one sub-lattice to achieve the selected rate set; modulating a least a first data stream using a selected sub-lattice; modulating at lease one other data stream using any desired modulation scheme; pre-cancelling the modulated at least one other data stream from the modulated at least first data stream and combining them into a single signal vector; and quantizing the single signal vector onto a fine lattice for transmission to the plurality of WTRUs.