Overview:

Wireless Sensor Networks convey sensed information over the wireless channel to a remote server for different applications such as weather monitoring and video surveillance. Such networks are characterized by limited computing, communication and energy resources. In this project, we develop the algorithms and systems to realize wireless sensors networks with high energy-efficiency and high performance sustainability.

Impact:

Wireless Sensor Networks are now garnering increased attention for many resource monitoring applications. One of the key challenges in such networks is to achieve high performance while maximizing the lifetime of the network, since the sensor nodes are typically battery powered and resource limited.

The key contributions of this work are novel approaches to enhance the sustainability and longevity of wireless sensor networks using cooperative transmission. We design a new paradigm for communication called Communication through Silence (CtS) [1], that improves the energy efficiency by leveraging a new dimension 'time' combined with minimal energy to deliver information efficiently. We also design an adaptive diversity routing protocol called Proteus [2] that decides how physical layer cooperation can be leveraged to achieve the right rate and range improvements of wireless links. Finally, we use wireless sensor networks to generate cues about user behavior in homes and optimize the delivery of video over IP networks using a solution called Cue- Based Networking (CBN)[3].

Concept:

A wireless sensor network architecture is illustrated in Figure 1, where sensors are connected together and communicate to a remote monitoring station. CtS is a new communication strategy that conveys information using silent periods in tandem with small amount of energy. The start and stop of the information is conveyed using short packets and the receiver counts the intermediate duration to infer the information. Similarly, Proteus leverages cooperation among nearby nodes in a sensor network, models the rate and range of cooperative links and incorporates them into a simple routing metric to decide the correct cluster size, rate and range of links on each path. Finally, sensors in CBN provide additional information about the user such as his presence or channel switching to inform the video server in a proactive manner.

Results:

In simulations and in real-life experiments, CtS significantly enhances the energy performance compared to traditional paradigms as illustrated in Figure 2. Similarly, Figure 3 illustrates how Proteus improves the scalability of performance with increasing number of hops. Figure 4 illustrates the improvement in video performance using the CBN solution.

Figure 1: Sensor Network Architecture

Figure 2: CtS improves energy performance

Figure 3: Proteus improves scalability

Figure 4: CBN optimizes video performance

Publications:

1. Y. Zhu and R. Sivakumar, "Challenges: Communication through Silence in Wireless Sensor Networks," ACM International Conference on Mobile Computing and Networking (MOBICOM), Cologne, Germany, August 2005.
2. S. Lakshmanan and R. Sivakumar, "Diversity Routing for Multi-hop Wireless Networks with Cooperative Transmissions," IEEE Communications Society Conference on Sensor, Mesh and Ad hoc Communications and Networks (SECON), Rome, Italy, June 22-26, 2009.
3. Y. Jeong, S. Lakshmanan, S. Kakumanu, and R. Sivakumar, "Cue-based networking using wireless sensor networks", ACM/Springer Wireless Networks Journal (WINET), vol. 17, no. 3, pp. 567-582, 2011.
4. Y. Jeong, S. Lakshmanan, S. Kakumanu, and R. Sivakumar, "Cue-based Networking using Wireless Sensor Networks: A Video-over-IP Application," IEEE Communications Society Conference on Sensor, Mesh and Ad hoc Communications and Networks (SECON), San Francisco, CA, June 16-20, 2008.

People:

• Sriram Lakshmanan (Student)
• Sandeep Kakumanu (Student)
• Raghupathy Sivakumar (Professor)