Abstract: An automatic gain control and its method are disclosed. An average power computing unit computes the power of a received signal. A power range monitoring unit monitors its change. If the signal power fluctuates around a threshold, the system enters an acquisition mode and the gain is tuned back to a default value. If the signal power is above an upper limit of a tracking range, a gain decreasing unit reduces the gain. If the signal power goes below a lower limit of the tracking range, a gain increasing unit raises the gain. Once the power falls in the tracking range, the system enters a tracking mode to make immediate responses toward the gain of the received signal.

Abstract: This specification discloses a packet type arbitrator in a wireless local area network (WLAN) and its arbitrating method. The arbitrator contains at least two packet type detectors and a packet type decider. The packet type detector is installed with a false alarm checking module and a timer according to the strength of the packet for delaying the decision from the packet type decider. Through the checking mechanism of the false alarm checking module and the timer, erroneous decision can be avoided when determining the packet type.

Abstract: A system and method for channel estimation in a wireless local area network. A corresponding channel estimation method includes the steps of: receiving a preamble message and despreading the preamble message into several symbol signals, each symbol signal containing several discrete signals; determining for each symbol signal a peak sign assignment; establishing several data windows for the symbol signals at the starting points of the discrete signals; multiplying the discrete value of each discrete signal of each data window by the corresponding peak sign assignment and accumulating the product in the first data frame; repeating the above steps for the next discrete signal and accumulating them in the second data frame, . . . , the Nth data frame; computing the accumulated value in the data frames and obtaining the data frame with the maximum value; estimating a channel signal from the previously determined data frame.