Method, apparatus and computer program to efficiently acquire signals in a cognitive radio environment

A method comprising:

• detecting signal instances from within a received radiofrequency RF signal envelope, wherein detecting the signal instances is by a plurality of detectors in parallel that detect signal levels across the entire RF signal envelope and a plurality of comparators each having a threshold for a unique signal level such that an output of the plurality of comparators is a digital word which is stored in a local memory for determining the periodicities;
• grouping the signal instances according to signal level;
• determining periodicities among the grouped signal instances;
• matching a periodicity of one of the groups of signal instances to a known periodicity;
• estimating a frequency domain spectrum at a time instance derived from the matched periodicity;
• if an expected frequency pattern that occupies the derived time instance is found in the estimated frequency domain spectrum, synchronizing to a candidate signal that lies within the frequency pattern;
• and
• decoding content of the candidate signal and thereafter accessing a cognitive radio system based on the decoded content.

An apparatus comprising:

• at least one signal detector configured to detect signal instances within a received radiofrequency RF signal envelope;
• coupled to an output of each of the at least one signal detector, at least two comparators coupled in parallel to one another;
• a processor configured to:
• group the signal instances according to signal level,
• determine periodicities among the grouped signal instances, where the periodicities comprise symbol or frame repetition patterns within thresholds set by the at least one signal level detector in at least two different wireless systems,
• match a periodicity of one of the grouped signal instances to a known periodicity,
• estimate a frequency domain spectrum at a time instance derived from the matched periodicity,
• and if an expected frequency pattern is found in the estimated frequency domain that occupies the derived time instance the processor is configured to synchronize a receiver of the apparatus to a candidate signal that lies within the frequency pattern;
• and
• the receiver is configured, with the processor, to decode content of the candidate signal and to access a cognitive radio system based on the decoded content.

A memory embodying a program of machine-readable instructions executable by a digital data processor to perform actions directed toward determining a traffic channel, the actions comprising:

• detecting signal instances within a received radiofrequency RF signal envelope;
• grouping the signal instances according to signal level;
• determining periodicities among the grouped signal instances;
• matching a periodicity of one of the groups of signal instances to a known periodicity, wherein matching the periodicity comprises finding a position of a wanted signal in the frequency domain using the determined periodicities as time domain results and detecting features of the wanted signal in the frequency domain with a receiver powered on;
• estimating a frequency domain spectrum at a time instance derived from the matched periodicity;
• if an expected frequency pattern that occupies the derived time instance is found in the estimated frequency domain spectrum, synchronizing to a candidate signal that lies within the frequency pattern;
• and
• decoding content of the candidate signal and thereafter accessing a cognitive radio system based on the decoded content.