Minimization of radiation exposure from mobile phone base stations by power controlling and coordinated multipoint joint transmission

Abstract

Radiation hazard from rapidly increasing BSs of cellular communication network is a burning issue of the day. A significant number of studies have been done on the effect of electromagnetic radiation. The number of research work on measuring the power density from mobile phone BSs is also notable whereas the research on the reduction of radiation from mobile phone BSs is insignificant. There are few ideas available to reduce radiation i.e., power control, use of distributed antenna system (DAS) and coordinated multi point joint transmission (CoMP-JT). However, there is hardly any study on how to use these techniques and how much radiation can be reduced by applying these techniques. In this thesis, the problem of reduction of radiation from mobile phone BSs is considered. For the study, a hexagonal cellular system with downlink traffic and frequency division duplex (FDD) technique is considered. First, the traditional cellular system is considered where all the BSs use the same transmission power. An analytical model is used to determine radiation exposure to the cell phone users. Applying this model in a typical cellular network, it is found that the radiation exposure from mobile phone BSs is significant. The effects of antenna height and traffic intensity on the radiation exposure are also studied. The safe distances under various standards are also determined for a given BS transmit power. Next, power control and user scheduling problems are considered for the reduction of radiation exposure to the users. An algorithm is developed for configuring the transmit power and user scheduling to reduce the power density to the users by satisfying the required downlink traffic of the users. The performance of the algorithm is evaluated and demonstrated that the algorithm is very effective in reducing power density to the mobile phone users. It is found that the radiation density under proposed algorithm is approximately 1/106 times of that of the traditional system. Finally, CoMP-JT technique is considered to reduce radiation exposure from mobile phone BSs. An algorithm is developed to configure the transmit power and CoMP-JT scheduling to reduce radiation exposure to the mobile phone users by satisfying the traffic requirement of the users. The performance of the developed algorithm is evaluated and found to be effective. It is also found that the developed algorithm can help in the reduction of a significant amount of radiation exposure when the edge users are located at equidistance from the BSs.