Effective transceiver selection for mobile multi-directional free-space-optical modules

Abstract

Demand for wireless data has increased significantly with the adoption of smartphones. To satisfy this huge demand, mobile operators are investing money and upgrading their infrastructure from 3G to 4G. However, it is expected that the demand will always stay hungry for more capacity and energy. This demand drives the need for alternate and complementary technologies in wireless communication. Free-space-optical (FSO) communication has the potential to serve as a complementary technology to RF for the future wireless networking. As a promising approach, multi-element spherical modules covered with multiple highly directional FSO transceivers has been shown to work well to handle mobility for FSO communication. Among other issues, the directionality of FSO communication necessitates a key problem to be solved in such modules: Maintaining the line-of-sight (LOS) among the mobile modules during an ongoing transmission. For FSO modules with many transceivers, reducing the modules' energy consumption becomes a crucial issue for the practicality multi-element FSO designs targeting mobile and ad- hoc settings. Although activating more transceivers on a module makes it easier to maintain LOS alignments between mobiles, it clearly uses more energy. In order to address explore tradeoff, this paper presents energy efficient mechanisms that aim to select an optimal subset of the directional transceivers in FSO modules. Index Terms—Free-space-optics; mobile ad-hoc networks; spherical FSO modules; channel selection algorithms