the scope of various embodiments of the invention is not limited in this respect fig4 shows a flow chart of a method of operation which may be performed by a mobile device according to an embodiment of the invention in flow chart 400 at 410 a multicast poll may be received containing the address or other identifier of this mobile device at 420 the timing indicator associated with this mobile device may be extracted from the multicast poll and a time delay may be determined from the timing indicator at 430 the mobile device may wait until the time delay determined at 420 has expired the time delay may be measured from any feasible staring point as previously described upon expiration of the time delay the mobile device may transmit its own response at 440 embodiments of the invention may be implemented in one or a combination of hardware firmware and software embodiments of the invention may also be implemented as instructions stored on a machine readable medium which may be read and executed by a processing platform to perform the operations described herein a machine readable medium may include any mechanism for storing or transmitting information in a form readable by a machine e g a computer for example a machine readable medium may include read only memory rom random access memory ram magnetic disk storage media optical storage media flash memory devices electrical optical.