Synchronization preamble method for OFDM waveforms in a communications system

A highly bandwidth-efficient communications system, comprising:

• means for forming a synchronization burst at an antenna element of a base station, including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• means for transmitting the synchronization burst from the antenna element at a base station reference instant of time;
• means for receiving the synchronization burst at a remote station during a remote station receive time window which begins at a remote station reference instant of time established by a remote station clock;
• means for recognizing the pattern of the plurality of tone frequencies as having the base station as the source of the synchronization burst;
• means for transmitting an error signal back to the base station at an instant referenced with respect to the remote station reference instant of time, in response to the recognizing means;
• means for deriving from the error signal a correction value related to a relative time error between the base station reference instant of time and the remote station reference instant of time;
• and
• means for transmitting the correction value to the remote station to correct the remote station clock.

A highly bandwidth-efficient communications method, comprising:

• forming a synchronization burst at a terrestrial base station, wherein the synchronization burst includes a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• transmitting the synchronization burst at a base station reference instant of time, wherein the synchronization burst uniquely identifies the base station to a remote station;
• receiving an error signal back from the remote station at an instant referenced with respect to a remote station reference instant of time;
• deriving a correction value from the error signal, related to a relative time error between the base station reference instant of time and the remote station reference instant of time;
• and
• transmitting the correction value to the remote station to correct timing at the remote station.

A highly bandwidth-efficient communications system, comprising:

• means for forming a synchronization burst at a terrestrial base station, wherein the synchronization burst includes a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• means for transmitting the synchronization burst at a base station reference instant of time, wherein the synchronization burst uniquely identifies the base station to a remote station;
• means for receiving an error signal back from the remote station at an instant referenced with respect to a remote station reference instant of time;
• means for deriving a correction value from the error signal, related to a relative time error between the base station reference instant of time and the remote station reference instant of time;
• and
• means for transmitting the correction value to the remote station to correct timing at the remote station.

A highly bandwidth-efficient communications method, comprising:

• receiving at a base station a signal on a reverse link from a remote station, having significant interference;
• forming a forward synchronization burst at the base station, including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• selectively forming at the base station a request signal requesting the remote station to respond with a reverse synchronization burst, including a plurality of tone frequencies arranged in the distinctive orthogonal frequency division multiplexed pattern;
• transmitting the forward synchronization burst and the request signal at a base station reference instant of time to the remote station;
• receiving at the base station a signal on the reverse link from the remote station the reverse synchronization burst and an error signal at an instant referenced with respect to a remote station reference instant of time;
• recognizing at the base station the reverse synchronization burst and deriving a correction value from the error signal, related to a relative time error between the base station reference instant of time and the remote station reference instant of time;
• and
• transmitting the correction value to the remote station to correct the remote station.

A highly bandwidth-efficient communications system, comprising:

• means for receiving at a base station a signal on a reverse link from a remote station, having significant interference;
• means for forming a forward synchronization burst at the base station, including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• means for selectively forming at the base station a request signal requesting the remote station to respond with a reverse synchronization burst, including a plurality of tone frequencies arranged in the distinctive orthogonal frequency division multiplexed pattern;
• means for transmitting the forward synchronization burst and the request signal at a base station reference instant of time to the remote station;
• means for receiving at the base station a signal on the reverse link from the remote station the reverse synchronization burst and an error signal at an instant referenced with respect to a remote station reference instant of time;
• means for recognizing at the base station the reverse synchronization burst and deriving a correction value from the error signal, related to a relative time error between the base station reference instant of time and the remote station reference instant of time;
• and
• means for transmitting the correction value to the remote station to correct the remote station.

A highly bandwidth-efficient communications method, comprising:

• forming a synchronization burst at an antenna element of a base station, including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed code pattern unique to the base station;
• transmitting the synchronization burst from the antenna element at a base station reference instant of time;
• receiving the synchronization burst at a remote station;
• recognizing the code pattern of the plurality of tone frequencies as having the base station as the source of the synchronization burst;
• transmitting an error signal back to the base station;
• deriving from the error signal a correction value;
• and
• transmitting the correction value to the remote station to synchronize the remote station.

A highly bandwidth-efficient communications method, comprising:

• receiving at a base station a signal on a reverse link from a remote station, having significant interference;
• forming a forward synchronization burst at the base station, including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• selectively forming at the base station a request signal requesting the remote station to respond with a reverse synchronization burst, including a plurality of tone frequencies arranged in the distinctive orthogonal frequency division multiplexed pattern;
• transmitting the forward synchronization burst and the request signal to the remote station;
• receiving at the base station a signal on the reverse link from the remote station the reverse synchronization burst;
• and
• recognizing at the base station the reverse synchronization burst.

A wireless communications method to enable a base station and its remote station to synchronize in a noisy environment, comprising:

• receiving at a base station a signal on a reverse link from a remote station, accompanied by significant interference;
• forming at the base station a request signal in response to the significant interference, the request signal requesting the remote station to respond with a reverse synchronization burst;
• transmitting from the base station a forward synchronization burst and the request signal to the remote station;
• preparing a reverse synchronization signal at the remote station in response to the request;
• and
• preemptively transmitting the reverse synchronization signal from the remote station during a time slot in a transmission frame from the remote station to the base station, that would otherwise be occupied by control or traffic signals.

A wireless communications method to enable a base station and its remote station to synchronize in a noisy environment, comprising:

• receiving at a base station a signal on a reverse link from a remote, accompanied by significant interference,
• forming at the base station a request signal in response to the significant interference, the request signal requesting the remote station to respond with a reverse synchronization burst;
• transmitting from the base station a forward synchronization burst and the request signal to the remote station;
• preparing a reverse synchronization signal at the remote station in response to the request;
• preemptively transmitting the reverse synchronization signal from the remote station during a time slot in a transmission frame from the remote station to the base station, that would otherwise be occupied by control or traffic signals, the reverse synchronization signal having an error;
• receiving at the base station the reverse synchronization signal having the error;
• deriving a correction value from the error at the base station;
• and
• transmitting the correction value from the base station to the remote station to correct the remote station.

A wireless communications method to enable a base station and its remote station to synchronize in a noisy environment, comprising:

• receiving at a base station a signal on a reverse link from a remote, accompanied by significant interference,
• forming at the base station a request signal in response to the significant interference, the request signal requesting the remote station to respond with a reverse synchronization burst;
• transmitting from the base station a forward synchronization burst and the request signal to the remote station, the synchronization burst including a plurality of tone frequencies arranged in a distinctive orthogonal frequency division multiplexed pattern unique to the base station;
• preparing a reverse synchronization signal at the remote station in response to the request;
• preemptively transmitting the reverse synchronization signal from the remote station during a time slot in a transmission frame from the remote station to the base station, that would otherwise be occupied by control or traffic signals, the reverse synchronization signal having an error;
• the reverse synchronization burst includes a plurality of tone frequencies arranged in the distinctive orthogonal frequency division multiplexed pattern used by the base station in the forward synchronization burst;
• receiving at the base station the reverse synchronization signal having the error;
• deriving a correction value from the error at the base station;
• and
• transmitting the correction value from the base station to the remote station to correct the remote station.