Why headache using GSM cellular phones?

Many research results on biological effects of cellular phone radiations agree that the main possible hazards are the thermal effects while some other results reveal that the thermal effects due to handsets radiation are negligible. Few can deny the fact and puzzle that some users did suffer from such symptoms as headaches due to cellular phones. This paper provides a potential cause or possible answer to the puzzle through analysis and understanding of GSM standards. We can also reveal that the low power low duty cycle pulsed train amplitude envelop modulation of GSM uplink signals is the main cause of such non-thermal biological effect for non-ionizing radiation.