Patent Document ID: 6097763
Application ID: 08962046
Patent Flag: 1

Claim One:
1. In a data communication system comprising a multicarrier transmitter which encodes and modulates input data onto a plurality of carriers, generates n samples of a transmit signal, and then appends to the front of the block of N samples a cyclic prefix of L samples before transmitting all (N+L) samples, a channel which severly distorts signals input to it by the transmitter, and a multicarrier receiver which includes an equalizer which partially equalizes the distorted signals it receives from the channel, and means for removing the L samples of the cyclic prefix, and then demodulating and decoding the remaining N samples, a method of calculating a set of M windowed time-domain equalizer parameters t.sub.w of said equalizer, wherein L, M and N are positive integers, said method comprising the steps of: (a) initializing said windowed time-domain equalizer parameters t.sub.w and a set of time-domain channel target response parameters f.sub.u to some predetermined initial values; (b) transforming said windowed time-domain equalizer parameters t.sub.w to obtain windowed frequency-domain equalizer parameters T.sub.w ; (c) transforming said time-domain channel target response parameters f.sub.u to obtain frequency-domain channel target response parameters F.sub.u ; (d) calculating, in said multicarrier transmitter, a set of N frequency-domain samples of a repetitive multicarrier signal X; (e) encoding and transmitting said repetitive multicarrier signal X from said multicarrier transmitter through said channel and into said multicarrier receiver to produce a frequency-domain received signal R; (f) averaging said frequency-domain received signal R to obtain averaged frequency-domain received signal Y; (g) generating, in said multicarrier receiver, a set of N frequency-domain samples of a local replica X' of said repetitive multicarrier signal X; (h) using said windowed frequency-domain equalizer parameters T.sub.w, said averaged frequency-domain received signal Y, and said local replica X' to update said frequency-domain channel target response parameters F.sub.u ; (i) transforming said frequency-domain channel target response parameters F.sub.u to produce a set of time-domain channel target response parameters f.sub.u ; (j) windowing said time-domain channel target response parameters f.sub.u by selecting L consecutive samples of f.sub.u to produce a set of windowed time-domain channel target response parameters f.sub.w ; (k) transforming said windowed time-domain channel target response parameters f.sub.w to produce a set of windowed frequency-domain channel target response parameters F.sub.w ; (l) using said windowed frequency-domain channel target response parameters F.sub.w, said local replica X', said windowed frequency-domain equalizer parameters T.sub.w and said averaged frequency domain received signal Y to obtain an updated set of frequency-domain equalizer parameters T.sub.u ; (m) transforming said frequency-domain equalizer parameters T.sub.u to produce a set of time-domain equalizer parameters t.sub.u ; (n) windowing said time-domain equalizer parameters t.sub.u by selecting M consecutive samples of t.sub.u to produce a set of said windowed time-domain equalizer parameters t.sub.w ; and (o) repeating steps (e) through (n) until a predetermined convergence condition is determined.