Device Symbiosis       


 Chandrasekhar (Chandra) Narayanaswami photo

Device Symbiosis - Symbiosis Examples

Audio Symbiosis - 2005

Mobile devices offer a private audio channel. A user can view a video shown on a public display such as a train and listen to the corresponding audio on his headset attached to his headphone. This division of media ensures that passengers who are not interested in the program do not have to put up with the sound.

The audio quality of personal headsets is generally acceptable for large sections of the population. However, large speakers in varying spatial configurations are able to deliver a broader range of experiences. For example, audio from a mobile device can be listened to on a high fidelity audio system.

We believe that the Session Initiation Protocol (SIP) can play an important role in audio symbiosis. An interesting feature of SIP is the ability to separate the control and media portions of a connection. In fact, they may take place at different devices. Thus SIP allows a level of indirection and late binding of the media device. This is a powerful concept and has the potential to do for communications what pointers did for programming by separating data from addresses and virtual memory did for large programs by creating virtual addresses to overcome limits of real addresses.

More details on audio symbiosis are available from our experience with SIP and following publications

Unleashing the power of wearable devices in a SIP infrastructure, Arup Acharya, Stefan Berger, Chandra Narayanaswami, Proc of IEEE PerCom 2005, pp. 159-168. Extended version invited for publication in Elsevier Pervasive and Mobile Computing Journal.

Display Symbiosis 2004-2005

The below table shows that limits of human visual acuity constrain the amount of information that can be shown on direct view displays of small portable devices. Until flexible displays or portable projection displays for small devices become practical, we will be limited by the size of the device. Though wearable eye mounted displays are already available, they have not been adopted in large numbers due to social concerns. Display symbiosis provides a way to overcome this inherent limitation of mobile devices.

Display Type User Distance (inches) Typical Width (inches) Typical Width (pixels Typical Resolution (dpi) Maximum Resolution (dpi) Maximum Width (pixels)
Cell phone panel 10 1 100 100 350 350
PDA Display 12 2 300 150 291 582
Laptop Display 16 10 1200 120 218 2180
Desktop Monitor 20 15 2000 133 175 2625
Meeting Room Screen 230 80 1200 15 15 1200

Typical resolution of displays and maximum possible resolution according to limitations on human visual acuity, using 20/20 human visual acuity.

Personal devices can also offer a private display. The private display can be used to show personalized information such as a special frequent visitor price that is offered to the user while watching a commercial on a public display such as a television on a train. Another example is one where speaker notes are shown on the small private display while a presentation is being shown on a large screen. Close captions for movies and television shows is another example.

More details on display symbiosis are available from following publications

Fostering a Symbiotic Handheld Environment, Mandayam Raghunath, Chandra Narayanaswami, Claudio Pinhanez, IEEE Computer, Sept 2003, pp. 55-65.

Using Symbiotic Displays to View Sensitive Information in Public, Stefan Berger, Rick Kjeldsen, Claudio Pinhanez, Mark Podlaseck, Chandra Narayanaswami, Mandayam Raghunath, Proc of IEEE PerCom 2005, pp 139-148.

Expanding the Digital Camera's Reach, Chandra Narayanaswami, M.T. Raghunath, IEEE Computer, Vol 37, No 12, Dec 2004, pp. 65-73.

Energy Symbiosis - 2004

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.