Patent ID: 7821915

Claim:
An apparatus comprising: a receiver configured to wirelessly receive a packet of information that includes a known transmitted part and to digitize the received signal, the known transmitted part having subcarriers with known values; a signal-to-tone transformer to determine the modulated subcarriers of a received signal corresponding to the received packet; a channel storage unit coupled to the signal-to-tone transformer including: an initial channel calculator to calculate a function of the initial channel response of subcarriers from the known part of the received packet; a memory subsystem configured to at a first time store a function of an initial channel response corresponding to the known part of the received packet, and at later times to store additionally or instead updates to or of previous version or versions of the channel response; a channel corrector coupled to the channel storage unit and to the signal-to-tone transformer configured to correct the modulated subcarriers of the received signal for the respective channel using the contents of the memory subsystem; the channel corrector configured to form channel corrected constellation values for the received signal; a decision and channel drift circuit coupled to the channel corrector to form post-decision constellation values corresponding to the channel corrected constellation values and to form a measure of the channel drift from the post decision constellation values and the pre-decision constellation values; and an updating circuit coupled to the channel storage unit to update the memory subsystem with an updated value determined from previous contents of the memory subsystem and an update, the update determined from the memory subsystem contents and the measure of the channel drift between symbols, such that drift of the channel response is tracked.