User detection at the base station in a GSM 900 mobile phone system

Abstract

Typically mobile handsets are used in close proximity to the users head, hand and shoulder. The radio frequency energy received and produced by the handset interacts with biological tissue causing severe perturbations to the radio channel. Human tissue is both dispersive and lossy therefore both the frequency and amplitude of any wave interacting with a user either in the uplink or the downlink will be changed. Identification of the presence of humans can be achieved by comparisons between the channel impulse response with and without a human user. This paper presents measurements and analytical framework for the determination of human presence in a cellular communication system over the air channel comprising a human, a handset and base station. For this analysis the chosen bearer is GSM.