Directional radio response of a 802.11b device guided by radiolocation

This is the fourth in a series of articles describing fast radiolocation in 802.11b wireless networking. This work was motivated by two significant problems in radio communication: unknown location of sources, and rapid loss of signal strength with distance. Radiolocation described in this series of articles addresses these problems, both of which are fundamentally caused by the omnidirectional nature of radio transmission. First, the sourcepsilas bearing is obtained for every received packet, making it possible to determine the location of wireless nodes even from sparse traffic. Second, per-packet directional information is acquired in real time, before the arrival of the next packet. This information is used to guide the directional response to interlocutor nodes with negligible delay, switching the transmission between the directional elements of the same antenna array that is used for radiolocation. Previous articles focused on the radiolocation methodology, and on the issue of integrating radiolocation with networking. The result of this development is a functioning laboratory prototype, capable of bidirectional communication with standard wi-fi equipment, and using radiolocation to guide its directional response. This article describes the prototypepsilas architecture, and the implementation of the directional response.