Example devices described herein include endpoint devices which may communicate with an access point device by modulating a channel associated with the wireless communication to encode transmit data. The channel modulation may be performed by utilizing a switch to control an impedance of an antenna at the endpoint device to either reflect or absorb wireless network communication signals received by the endpoint device. The access point device may extract the transmit data by decoding changes in the channel caused, at least in part, by the modulation. Access point devices may transmit a pattern of packetsthe presence or absence of which may correspond with transmit data. Endpoint devices may decode this data by using an energy detector to differentiate between the presence or absence of a packet.

A system and method for tracking a group of individuals comprising: a wireless tracking device provided to at least one or more individuals within a group, wherein the wireless tracking device is configured for bi-directional communications with a monitoring center that establishes dynamic geo-fencing limitations in real-time for all group members provided with the wireless tracking device based on the group's center of gravity as they travel, whereby the geo-fence is in constant motion, and the wireless tracking device is adapted to determine and store absolute location information of each wireless tracking device provided to group members; and viewing device configured for displaying identification information concerning each individual wireless tracking device within the group on a rotating map display oriented relative to the group leader's location information.

A wireless battery management system includes a computing device and first and second battery unit monitoring modules. The computing device includes an output data request port and an input data port. In response to a data request from the output data request port of the computing device, a first battery unit monitoring module transmits data of the first battery unit to the input data port of the computing device wirelessly and may transmits a data request to the second battery unit monitoring module. In response, the second battery unit monitoring module may transmit data of the second battery unit to the input data port of the computing device wirelessly or transmit data of the second battery to the first module for wireless transmission. In addition, each battery unit monitoring module may communicate wirelessly and independently with the computing device.