Method and system of reducing collisions in an asynchronous communication system

A method of reducing collisions in an asynchronous communication system, comprising the steps of:

• receiving at least one preamble waveform among a set of different preamble waveforms which toggle between two symbol frequencies, the different preamble waveforms being distinguishable by at least having one among a different symbol frequency spacing and a different symbol toggling duty cycle;
• selecting to decode a preamble waveform among the set of different preamble waveforms based on at least one among the different symbol frequency spacing and the different symbol toggling duty cycle;
• and
• basing a desired preamble waveform on a receiver's call types and identifiers associated with each of the receiver's call types that are available.

A mobile device having a wireless transmitter arranged to transmit a preamble signal to wake up specified target receivers, the wireless transmitters comprising:

• a signal generator for generating a set of known preamble waveforms;
• a signal source that alters at least one of the preamble waveforms in the set of preamble waveforms to provide a distinguishable preamble waveform from a remaining set of preamble waveforms;
• and
• a transmitter apparatus coupled and responsive to the signal source to transmit to another mobile unit in an asynchronous communication system at least one among the set of preamble waveforms made distinguishable based on an association with a call type and a target identifier.

A wireless receiver arranged to detect a preamble signal among a set of known preamble waveforms to exit a standby mode, the wireless receiver comprising:

• a receiver for scanning, asynchronously and sequentially during a wakeup time, a plurality of communication resources;
• a sampler, coupled to the receiver, for collecting a plurality of received sample sequences, one sample sequence collected at each of the plurality of communication resources;
• and
• a controller coupled to the receiver and sampler, programmed to calculate, for each of the plurality of communication resources, a correlation between a received signal and an undistorted version of a transmitted preamble waveform, for every known preamble waveform within the set;
• and wherein a desired preamble signal is based on a call type and a receiver ID associated with the call type.