Delay compensation
First Claim
1. A highly bandwidth-efficient communications method, comprising:
- receiving at a base station during a first time period a first spread signal from a first remote unit, said signal having a first common access channel data signal spread over a first plurality of discrete tones in accordance with a first spreading code assigned to said first remote unit;
receiving at the base station during a second time period a second spread signal from said second remote unit, said signal having a second common access channel data signal spread over a second plurality of discrete tones in accordance with a second spreading code assigned to said second remote unit, said second time period occurring at a different time than said first time period, said second time period occurring at a time expected by said base station;
adaptively despreading said first spread signal received at said base station by using a first despreading code that is based on the characteristics of said received signal;
calculating a delay at said base station, said delay being the time difference between the start of said second time period and said first time period, said delay having a magnitude and a direction; and
transmitting from said base station to said first remote unit a signal that includes said magnitude and said direction of said delay.
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Accused Products
Abstract
In a discrete tone system, a base station receives a transmission burst from a remote unit being installed that includes delay compensation pilot tones that are uniformly spread throughout the transmission bandwidth. The arrival time transmission burst is not synchronized with the other remote units transmitting to the base station. The base station measures the phase delay of each tone and calculates the delay of the remote unit from the slope of the line of phase angle versus tone frequency. The base station transmits a signal to the remote unit that includes the magnitude and direction of the delay, which allows the remote unit to adapt the timing of its transmission to be synchronized with the other remote units.
22 Citations
17 Claims
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1. A highly bandwidth-efficient communications method, comprising:
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receiving at a base station during a first time period a first spread signal from a first remote unit, said signal having a first common access channel data signal spread over a first plurality of discrete tones in accordance with a first spreading code assigned to said first remote unit;
receiving at the base station during a second time period a second spread signal from said second remote unit, said signal having a second common access channel data signal spread over a second plurality of discrete tones in accordance with a second spreading code assigned to said second remote unit, said second time period occurring at a different time than said first time period, said second time period occurring at a time expected by said base station;
adaptively despreading said first spread signal received at said base station by using a first despreading code that is based on the characteristics of said received signal;
calculating a delay at said base station, said delay being the time difference between the start of said second time period and said first time period, said delay having a magnitude and a direction; and
transmitting from said base station to said first remote unit a signal that includes said magnitude and said direction of said delay. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 13, 14, 15, 16, 17)
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Specification