[1] A very similar opportunistic routing scheme was also independently proposed by Zhenzhen Ye and Yingbo Hua from University of California, Riverside and presented in a paper in 2005.
The algorithm is designed to convey packets of the Internet Protocol, so that it enables the maximum number of other services.
At the time of invention, digital radios had widely replaced wireline internet services for portable devices.
MIT at that time (2005) was involved with the One Laptop per Child project, an attempt to make an inexpensive low-power computer to help educate impoverished children.
The advantages were thought to be reduced costs for digital copies of books and consumables like paper, with possible pedagogic improvements from the interactivity and flexibility.
A practical but superior network algorithm would directly help educate more children by reducing the cost and power needed by the laptop.
The estimate is calculated based on the number of packets in the batch, and the probabilities of a correct transmission from each intermediate radio.
ExOR uses a conventional routing protocol "RRTc" to collect information about the probability of a successful transmission between each pair of digital radios in the network.
In this way, the information about the progress of the packets flows backward toward the source as radios farther from the destination update their batch maps by eavesdropping on retransmissions.
Some time is wasted by having the receiver broadcast packet information, but this is far less than the normal routing schemes, which can retransmit when an acknowledge message is lost.
Response time in some games might be affected by larger amounts of buffering in high efficiency networks.
ExOR's efficiency estimates are based on a real implementation with a Linux routing toolkit called click.
Experimental versions of the software were both simulated and installed on a rooftop network called "RoofNet" in Cambridge, Massachusetts.