Apparatus and method for timing synchronization in OFDM-based wireless systems

Apparatus for use in adjusting timing in a wireless communication system including a base station and at least one mobile station comprising:

• in said base station, a receiver for receiving a signal including a plurality of tones from at least one mobile station,
• a first prescribed processor supplied with said received tones for generating a corresponding plurality of complex scalars of the mobile user transmission channel, and
• an estimate processor supplied with said plurality of complex scalars for generating a single prescribed parameter representative of delay characteristics of said mobile user transmission channel and for utilizing said single prescribed parameter representative of delay characteristics in accordance with prescribed criteria to generate said timing control signal;
• and
• in said mobile station, an adjustable time transmit symbol clock responsive to said timing control signal received from said base station for controllably delaying or advancing said transmit symbol clock,
• wherein proper positioning of a transmitted mobile signal is ensured in the optimum sampling window at a base station by being responsive to said timing control signal to controllably delay or advance said transmit symbol clock.

Apparatus for use in a wireless communications system for generating a timing control signal comprising:

• means for receiving a signal including a plurality of tones from at least one mobile station;
• first means supplied with said received tones for generating a corresponding plurality of complex scalars of the mobile user transmission channel;
• and
• second means supplied with said plurality of complex scalars for generating a single prescribed parameter representative of delay characteristics of said mobile user transmission channel and for utilizing said single prescribed parameter representative of delay characteristics in accordance with prescribed criteria to generate said timing control signal,
• wherein said timing control signal is to be trasmitted to said mobile unit where it ensures proper positioning of a transmitted mobile signal in the optimum sampling window at a base station by being responsive to said timing control signal to controllably delay or advance a transmit symbol clock in said mobile unit.

A method for use in a wireless communications system for generating a timing control signal comprising the steps of:

• receiving a signal including a plurality of tones from at least one mobile station;
• in response to said received tones, generating a corresponding plurality of complex scalars of the mobile user transmission channel;
• and
• in response to said plurality of complex scalars, generating a single prescribed parameter representative of delay characteristics of said mobile user transmission channel and for utilizing said single prescribed parameter representative of delay characteristics in accordance with prescribed criteria to generate said timing control signal,
• wherein said timing control signal is to be transmitted to said mobile unit where it ensures proper positioning of a transmitted mobile signal in the optimum sampling window at a base station by being responsive to said timing control signal to controllably delay or advance a transmit symbol clock in said unit.