Distributed control in synchronizing remote units to host unit

Abstract

A method for an orthogonal frequency division multiplexing multipoint-to-point communications system is provided. The method includes establishing communication between a first remote unit of a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration, transmitting up to a plurality of tones from the first remote unit, the up to a plurality of tones modulated with upstream information using orthogonal frequency division multiplexing, and receiving information from the host unit to adjust transmission of the up to a plurality of tones from the first remote unit such that when any tones are transmitted from the first remote unit and at least one other remote unit of the plurality of remote units, all of the tones are substantially orthogonal when received at the host unit.

1 . A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising: 
 establishing communication between a first remote unit of a plurality of remote units and a host unit, the plurality of remote units communicatively coupled to the host unit in a multipoint-to-point configuration;    transmitting up to a plurality of tones from the first remote unit, the up to a plurality of tones modulated with upstream information using orthogonal frequency division multiplexing; and    receiving information from the host unit to adjust transmission of the up to a plurality of tones from the first remote unit such that when any tones are transmitted from the first remote unit and at least one other remote unit of the plurality of remote units, all of the tones are substantially orthogonal when received at the host unit.    
     
     
         2 . The method of  claim 1 , wherein transmitting up to a plurality of tones from the first remote unit comprises transmitting the up to a plurality of tones over a distribution network.  
     
     
         3 . The method of  claim 2 , wherein transmitting over a distribution network comprises transmitting over one of a hybrid fiber/coax network and a wireless system.  
     
     
         4 . The method of  claim 1 , wherein receiving information from the host unit comprises receiving information from the host that was generated by the host unit based on prior transmissions from the first remote unit.  
     
     
         5 . The method of  claim 1 , wherein receiving information comprises receiving a command to adjust one or more of carrier frequency, power amplitude, and timing of the transmissions of the up to a plurality of tones from the first remote unit.  
     
     
         6 . A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising: 
 receiving an orthogonal frequency division multiplexing waveform at a multipoint-to-point host unit, the orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by the plurality of remote units; and    transmitting information from the multipoint-to-point host unit to at least one of the plurality of remote units, the information directing the at least one of the plurality of remote units to make a transmission adjustment to improve the orthogonal nature of the tones in the orthogonal frequency division multiplexing waveform.    
     
     
         7 . The method of  claim 6 , wherein receiving the orthogonal frequency division multiplexing waveform at the multipoint-to-point host unit further comprises receiving a plurality of tones from more than one of the plurality of remote units.  
     
     
         8 . The method of  claim 6 , wherein receiving the orthogonal frequency division multiplexing waveform at the multipoint-to-point host unit further comprises receiving a plurality of tones from one of the plurality of remote units.  
     
     
         9 . The method of  claim 6 , further comprising adjusting each of the plurality of remote units to achieve alignment within a predefined margin at the host unit of any upstream transmissions by the plurality of remote units.  
     
     
         10 . A method for an orthogonal frequency division multiplexing multipoint-to-point communications system, the method comprising: 
 receiving an orthogonal frequency division multiplexing waveform at a multipoint-to-point host unit, the orthogonal frequency division multiplexing waveform comprising a plurality of tones transmitted by a plurality of remote units; and    adjusting transmissions from at least one of the plurality of remote units based on the orthogonal frequency division multiplexing waveform so that the plurality of tones transmitted by the plurality of remote units are substantially orthogonal when received at the multipoint-to-point host unit.    
     
     
         11 . The method of  claim 10 , further comprising: 
 adjusting transmissions from the at least one of the plurality of remote units such that when any tones are transmitted from the at least one of the plurality of remote units and at least one other remote unit of the plurality of remote units, the tones are substantially orthogonal when received at the multipoint-to-point host unit.    
     
     
         12 . The method of  claim 10 , wherein receiving the orthogonal frequency division multiplexing waveform at the multipoint-to-point host unit further comprises receiving a plurality of tones from more than one of the plurality of remote units.  
     
     
         13 . The method of  claim 10 , wherein receiving the orthogonal frequency division multiplexing waveform at the multipoint-to-point host unit further comprises receiving a plurality of tones from one of the plurality of remote units.  
     
     
         14 . The method of  claim 10 , further comprising adjusting each of the plurality of remote units to achieve alignment within a predefined margin at the host unit of any upstream transmissions by the plurality of remote units.