Patent ID: 6097763
Filing Date: 2000-08-01
Classification: H04L

Abstract:
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.