Green handover — A new handover mechanism that minimizes radiation from mobile devices

In recent years, cellular technology has become very widespread, with over 4 billion users worldwide. The increase in usage has been accompanied by a growing concern related to the possible adverse effects of the cellular radiation on human health. The radiation from the cellular phone, which is in close proximity to the user, is of special interest for this matter. In this paper we propose a new handover mechanism for cellular networks, aiming at minimal emission from mobile phones. The criterion for handover in common cellular systems is based on the received downlink signal strength or signal quality. This criterion makes sense when the uplink and downlink are symmetric. However, the advent of MIMO technology changes this assumption since MIMO transmission and reception techniques may significantly alter the uplink and downlink characteristics. For example, the number of transmit antennas may differ from the number of receive antennas. Alternatively, the techniques may significantly differ, such as when the transmitter broadcasts the downlink signal whereas the receiver performs beamforming. Consequently a mobile phone may receive Cell A with best quality, whereas Cell B may receive the mobile at better quality than Cell A, and hence Cell B requires minimal emission from the mobile phone. The new handover mechanism uses this concept and chooses, among neighboring cells with sufficient downlink, the cell for which the emission from the mobile phone is minimized. This mechanism requires methods to estimate the expected uplink emission. We propose several such methods. These include procedures where cells broadcast their uplink reception capabilities or request mobiles to perform test transmissions. Finally, we discuss the application of the proposed handover mechanism to create a new bidding procedure aiming at minimal uplink transmission power and minimal exposure to radiation.