High speed modem for a communication network

Abstract

The present invention relates to a receiver at the head-end or a centralizing unit side in a communications system or network for signals in the upstream direction which is the direction from user to head-end or a centralizing unit that is linked to a number of users, the number being equal to or larger than one. The receiver of the invention is suited for the reception of burst-mode signals. The receiver performs a channel estimation on a per-burst basis in real time or essentially immediate. The channel estimation is necessary to do successful data detection of modulated data. The receiver of the invention performs the channel estimation and data detection in one compact all-digital mechanism that has no tuning parts. The reception method works in an aspect according to the principle of a matched filter receiver, but stores no local copy of the required matched waveform. Rather, a copy of the matched waveform is included in the preamble of the signals.

What is claimed is:  
     
         1 . A telecommunication system with an upstream communication system for communication from a user to a head-end over a channel, said upstream communication system having a head-end receiver comprising a detect unit configured in a feed-forward data-driven architecture.  
     
     
         2 . The telecommunication system as recited in  claim 1 , wherein said detect unit is adapted to receive a burst-mode signal, said burst-mode signal having a preamble with at least one training portion and at least one timing alignment portion.  
     
     
         3 . The telecommunication system as recited in  claim 2 , wherein said at least one training portion is positioned at the beginning of a communication burst and is followed by said at least one timing alignment portion.  
     
     
         4 . The system as recited in  claim 3 , wherein said burst-mode signal further comprises a user message.  
     
     
         5 . The system as recited in  claim 3 , wherein said user message comprises error correcting codes.  
     
     
         6 . The communications system as recited in  claim 4 , said upstream communication system having a transmitter for said user message, said user message being a first sequence of data, said transmitter comprising a preamble insertion unit configured to insert a predetermined sequence of data to said first sequence of data, said predetermined sequence having said training portion at the beginning of the predetermined sequence followed by said timing alignment portion.  
     
     
         7 . The communication system as recited in  claim 6 , wherein said preamble insertion unit is configured to prepend said predetermined sequence of data to said first sequence of data.  
     
     
         8 . The system as recited in  claim 6 , wherein the training portion comprises a step signal.  
     
     
         9 . The system as recited in  claim 8 , wherein the length of said user message is an algorithm parameter.  
     
     
         10 . The system as recited in  claim 8 , wherein the length of said user message is variable.