Carrier detection and parallel GSM cell search in multimode terminals

A wireless communication apparatus arranged to detect, among a plurality of modulated carrier signals of different frequencies, at least one of the modulated carrier signals modulated with a tone burst having a tone burst duration, wherein the modulated carrier signals are Global System for Mobile Communications (GSM) carrier signals and the tone burst is contained within a GSM Frequency Correction Channel (FCCH), the wireless communication apparatus comprising:

• a receiver adapted to receive signals in accordance with Third Generation Partnership Project Long Term Evolution specifications and arranged to provide a composite signal comprising the plurality of modulated carrier signals received simultaneously;
• an analog-to-digital converter arranged to generate samples of the composite signal;
• a block formation stage arranged to divide the samples of the composite signal into a plurality of blocks, each of the blocks comprising a number of samples corresponding to not more than half of the tone burst duration;
• a transform stage arranged to transform the samples of each block into frequency domain components;
• a group formation stage arranged to divide the frequency domain components of each block into a plurality of groups, each group corresponding to a range of frequencies occupied by a different one of the modulated carrier signals;
• a tone burst detection stage arranged to perform tone burst detection on each group;
• and
• a recording stage arranged to record which of the modulated carrier signals is modulated with the tone burst, according to which of the groups the tone burst is detected in.

A non-transitory machine-readable medium storing computer program code arranged for, when executed on a processor, processing samples of a composite signal comprising a plurality of modulated carrier signals of different frequencies according to the following steps, wherein the modulated carrier signals are Global System for Mobile Communications (GSM) carrier signals and at least one of the carrier signals is modulated with a tone burst having a tone burst duration and contained within a GSM Frequency Correction Channel (FCCH):

• dividing the samples of the composite signal into a plurality of blocks, each of the blocks comprising a number of samples corresponding to not more than half of the tone burst duration;
• transforming the samples of each block into frequency domain components;
• dividing the frequency domain components of each block into a plurality of groups, each group corresponding to a range of frequencies occupied by a different one of the modulated carrier signals;
• performing tone burst detection on each group;
• and
• determining which of the carrier signals is modulated with the tone burst,
• according to which of the groups the tone burst is detected in.