Abstract: A system providing passive intermodulation (PIM) interference cancellation in dual-band wireless network by utilizing a regular Tx and Rx as inputs for cancellation modeling. The system doesn't require an additional feedback circuit for modelling, making the circuits simple, cost-effective, and stable performance. It is proposed to use dual band modeling to apply separate dual-band PIM nonlinearity modeling, avoiding dealing with extremely high sampling rate with the conventional solution, where the dual bands are treated as a single band. The proposed approach makes the dual band PIM cancellation feasible. The system performing PIMI and PIMC filtering only on the UL band and decimates the cancellation sampling rate, the system performing: UL band modeling and cancellation by filtering out the unwanted spectrum, such as the transition band, and DL bands; and down-sampling on the filtered signal to further reduce the complexity and resource utilization.

Abstract: In an arrangement for transmitting traffic in asynchronous transfer mode (ATM) cells in downstream and upstream frames between an out station and a base station, upstream traffic cells are queued in each outstation in sequential order for subsequent transmission in upstream frames to the base station. Each outstation sends requests for allocation of timeslots to the base station, each said allocation request being transmitted to the base station in a respective time slot of a said upstream frame. The base station includes means for performing a periodic ranging measurement with each outstation whereby to determine a corresponding timing offset between the base station and that outstation and for communicating that timing offset to the outstation. Each outstation controls the timing of its cell allocation requests such that the cell allocation requests received by the base station in each upstream frame are each in a respective predetermined time slot of that frame.