Patent ID: 7848277
Filing Date: 2010-12-07
Classification: H04W,Y02D

Abstract:
1. A power management method for use in a first station and a second station in an ad hoc wireless local area network, the method comprising: the second station entering a NBI (Normal Beacon Interval) every certain number of BIs (Beacon Intervals), called an LI (Listen interval), for power saving and data receptions, wherein the LI comprises one NBI, some SBI (Sleep Beacon Intervals) and some BBIs (Beacon-Window-Only Beacon Intervals), wherein the NBI comprises an AW (ATIM Window) comprising a BW (Beacon Window), where the second station transmits and the first station receives beacon frames within the BW, the first station transmits and the second station receives ATIM frames within the AW, the second station returns an ATIM ACK (acknowledgement) to the first station that transmitted the ATIM frame and the second station remains awake after the AW ends to wait for the reception of data frames when having received the ATIM frame within the AW, and the first station returns a data ACK if a data frame is received, and each of the BBIs comprises the BW, where the second station broadcasts its beacon frame within the BW of the BBIs, and enters a doze state after the end of the BW in the BBI, and remains the doze state during the whole SBI, wherein the second station is disable from receiving and transmitting frames in the doze state, determining a number and the positions of the BBIs within the LI, wherein the number of the BBIs in the LI is no more than the half of the total number of BIs in the LI, and the positions of those respective BBIs are randomly selected, and the second station broadcasts a beacon frame within the BW of the BBIs, and enters the doze state in the BBI, wherein the second station is disabled from receiving and transmitting frames in the doze state, and the beacon frame comprises a RBI (Remaining number of BIs) representing the remaining number of BIs between the BBI where the beacon frame is transmitted and the NBI; the first station receiving the beacon frame from the second station via the ad hoc wireless local area network, recording the RBI corresponding to the second station, predicting the NBI of the second station according to the RBI, and transmitting a data frame to the second station at the NBI of the second station via the ad hoc wireless local area network; the second station transmitting the beacon frame comprising the LI value to the first station; the first station reducing the RBI by 1 when one of the BI passes; and setting the RBI as the LI value when the RBI equals 0.