Energy Symbiosis

The energy density of batteries is not keeping up with improvements in other areas such as processor speed, memory, and bandwidth. Already, the energy density in many batteries used in mobile devices is so high that several design precautions are necessary to prevent accidental leakage and explosion. Thus, energy conservation is an important challenge that will be relevant for several years.

Device symbiosis can help reduce the energy consumed in mobile devices by offloading some work from mobile devices and sensors to larger devices with better energy sources. For example, the Personal Mobile Hub offloads some of the computation and long range wireless communication from sensors. Bosdy worn biometric sensors need only a short range wireless interface that can reach the mobile hub worn on a belt that can then relay the message over longer distances.

Proxies on the network, such as the Power-Aware Streaming Proxy (PAWP) allow a mobile device to reduce the amount of energy it spends to receive web content. The PAWP architecture designed to schedule incoming web traffic into intervals of high and no communication. This traffic pattern allows WLAN interfaces to switch to a low power state after very short idle intervals. PAWP uses a collection of HTTP-level techniques to compensate any negative impact that traffic scheduling may have. PAWP does not require any client or web server modifications. The figure below shows that with PAWP, the mobile device can transition its wireless interface to a lower power mode after a burst of data is received instead of keeping it on for longer intervals.

More details on energy symbiosis are available from following publications

Personal Mobile Hub, Dirk Husemann, Chandra Narayanaswami, Michael Nidd, Proc of 8th Intl Symposium on Wearable Computers (ISWC) 2004, pp. 85-91.

The Power-Aware Streaming Proxy Architecture, (Invited Paper) M. Rosu, C. Olsen, L. Luo, C. Narayanaswami, Workshop on Broadband Wireless Multimedia (associated with BroadNets 2004), Oct 2004.

PAWP: A Power Aware Web Proxy for Wireless LAN Clients, Marcel Rosu, C Michael Olsen, Chandra Narayanaswami, Annie Luo, Proceedings of the Sixth IEEE Workshop on Mobile Computing Systems and Applications (WMCSA) 2004, pp 206-215.

Page was last updated in May, 2005.