Apparatus and method for communication

1. An apparatus comprising at least one processor configured to cause the apparatus to:

obtain as an input a sampled signal;

determine a parameter for a group of samples of the input signal corresponding to the length of one or two frames of a Global System for Mobile communication (GSM) signal, the parameter describing the shape of the group of samples;

determine peak to average power and peak to average power variance for the group of samples of the input signal corresponding to a length of one or two frames of a GSM signal;

compare the determined parameter to predetermined thresholds and the obtained peak to average power and peak to average power variance to predetermined thresholds; and

determine whether the input signal is a GSM-type signal on the basis of the comparisons.

2. The apparatus of claim 1 , at least one processor further configured to cause the apparatus to:

determine inverse magnitude of signal energy over a number of samples, the number of samples corresponding to a given number of GSM slots;

determine a peak value in the inverse magnitude of signal energy;

determine signal energy using a sample window centered over a peak value;

determine average energy outside the sample window;

calculate signal to noise ratio on the basis of the determined signal energy and average energy; and

determine whether the input signal is a GSM-type signal on the basis of the comparisons.

3. The apparatus of claim 1 , the apparatus being configured to determine received signal strength indicator for the group of samples of the input signal corresponding to the length of one or two frames of a GSM signal prior determining the parameter for the group of samples.

4. The apparatus of claim 3 , the apparatus being configured to compare the determined received signal strength indicator to a given threshold, and

determine whether the input signal is a GSM-type signal on the basis of the comparison, and output the determined received signal strength indicator and start analysing next group of samples.

5. An apparatus, comprising:

means for obtaining as an input a sampled signal;

means for determining a parameter for a group of samples of the input signal corresponding to the length of one or two frames of a Global System for Mobile communication (GSM) signal, the parameter describing the shape of the group of samples;

means for determining peak to average power and peak to average power variance for the group of samples of the input signal corresponding to a length of one or two frames of a GSM signal;

means for comparing the determined parameter to predetermined thresholds and the obtained peak to average power and peak to average power variance to predetermined thresholds; and

means for determining whether the input signal is a GSM-type signal on the basis of the comparisons.

6. A method for recognizing Global System for Mobile communication (GSM) signals, the method comprising:

obtaining as an input a sampled signal;

determining a parameter for a group of samples of the input signal corresponding to the length of one or two frames of a GSM signal, the parameter describing the shape of the group of samples;

determining peak to average power and peak to average power variance for the group of samples of the input signal corresponding to a length of one or two frames of a GSM signal;

comparing the determined parameter to predetermined thresholds and the obtained peak to average power and peak to average power variance to predetermined thresholds; and

determining whether the input signal is a GSM-type signal on the basis of the comparisons.

7. The method of claim 6 , further comprising:

determining inverse magnitude of signal energy over a number of samples, the number of samples corresponding to a given number of GSM slots;

determining a peak value in the inverse magnitude of signal energy;

determining signal energy using a sample window centered over a peak value;

determining average energy outside the sample window;

calculating signal to noise ratio on the basis of the determined signal energy and average energy; and

determining whether the input signal is a GSM-type signal on the basis of the comparisons.

8. The method of claim 6 , further comprising:

determining received signal strength indicator for the group of samples of the input signal corresponding to the length of one or two frames of a GSM signal prior determining the parameter for the group of samples.

9. The method of claim 8 , further comprising:

comparing the determined received signal strength indicator to a given threshold;

determining whether the input signal is a GSM-type signal on the basis of the comparison, and output the determined received signal strength indicator and start analysing next group of samples.

10. A computer program product embodied on a non-transitory distribution medium readable by a computer and comprising program instructions which, when loaded into an apparatus, execute a computer process comprising:

obtaining as an input a sampled signal;

determining a parameter for a group of samples of the input signal corresponding to the length of one or two frames of a GSM signal, the parameter describing the shape of the group of samples;

determining peak to average power and peak to average power variance for the group of samples of the input signal corresponding to a length of one or two frames of a GSM signal;

comparing the determined parameter to predetermined thresholds and the obtained peak to average power and peak to average power variance to predetermined thresholds; and

determining whether the input signal is a GSM-type signal on the basis of the comparisons.