Patent ID: 7020165
Filing Date: 2006-03-28
Classification: H03M,H04B,H04H,H04J,H04L,H04N,H04W

Abstract:
1. A ranging process carried out to achieve frame synchronization in any digital data communication system having a plurality of physically distributed remote transceivers transmitting frames of the same size on the same frequency on a shared medium to a headend transceiver, comprising the steps: (a) iteratively transmitting a ranging signal that has correlation properties such that it can be found in the presence of noise, and conducting a trial and error adjustment of a transmit frame timing delay value prior to each transmission of said ranging signal until receiving a message from said headend transceiver that a ranging signal has been found in a gap surrounding a reference time in an upstream payload data channel, said gap being an interval during upstream transmissions on said upstream payload data channel from said plurality of distributed remote transceivers to said headend transceiver when transmissions of anything other than ranging signals by said remote transceivers is not permitted; (b) when said message is received by the remote transceiver that transmitted said ranging signal, holding said transmit frame timing delay at the same value it had just before receiving said message, and transmitting identifying information to said headend transceiver to identify said remote transceiver; and (c) receiving a message from said headend transceiver transmitted on a downstream payload data channel and directed to said remote transceiver which transmitted said identifying information indicating by how much to adjust said transmit frame timing delay such that frames transmitted from said remote transceiver will have their frame boundaries exactly or almost exactly aligned in time at the location of said headend transceiver with the frame boundaries of frames transmitted from other said remote transceivers.