This paper presents Codecast, a many-to-many communication protocol for low-power sensor networks that provide high throughput and reliable data sharing from multiple sources to multiple destinations of a network. Codecast uses physical layer capture on concurrent transmissions for high spatial reuse and a network-assisted network coding for high throughput as the core techniques. Our extensive evaluation in two large-scale testbed deployments (Indriya and Flocklab) shows that Codecast provides up to 4x the throughput of Chaos and 1.8x the throughput of LWB for many-to-many data communication. Finally, we demonstrate the utility of Codecast through a distributed channel selection mechanism and a link state based routing protocol.

Synchronous transmission has been exploited recently for accelerating fundamental operations of wireless sensor networks like data dissemination, data collection, and network-wide agreement by an order of magnitude. Although these protocols (e.g., Glossy) have shown to be highly reliable for small packet sizes, the use of large packet sizes coupled with an excessive number of simultaneous transmissions can reduce reliability significantly. Our work is motivated by the observation that capture effect can improve the reliability of synchronous transmission. We experimentally study the effect of physical layer capture and identify guidelines in which it can be exploited to enhance reliability. Based on these observations, we propose Syncast, a data dissemination protocol that improves over Glossy by exploiting capture effect over multichannels. The evaluation shows that Syncast provides a robust, reliable, and scalable data dissemination of large packets with lower end-to-end delay and up to 92% reduced radio-on-time.

Time synchronization is an enabling service that allows devices to share a consistent notion of time and thus makes it easier to build efficient and robust collaborative services. However, existing synchronization protocols based on wireless packet transmissions are not energy efficient because powering the radio often consumes a significant fraction of the energy budget. In this paper, we propose PSync, a visible light-based time synchronization protocol that relies on an LED light source and is highly energy efficient for the receivers. The key novelty in our protocol is the use of a De Bruijn sequence to provide a rough estimate of time using a minimum amount of information. Experiments show that our scheme achieves an average synchronization error of 1.3 timer ticks (32 μs per clock tick). In addition, the additional energy consumed for one round of synchronization based on PSync can be as low as 19% of the energy needed to receive a small packet (1 byte) using IEEE 802.15.4 radio.

It is widely known that cross-technology interference (CTI) adversely affects the reliability of 802.15.4 (ZigBee) communications. With the 2.4 GHz ISM band getting increasingly congested because of multiple wireless technologies like IEEE 802.11 (WiFi), 802.16 (WiMax), and Bluetooth and common appliances like a microwave and a cordless phone sharing it, data collection becomes exceedingly challenging especially in unplanned CTI prevalent in urban environments. This demonstration presents Oppcast, a robust and energy-efficient data collection protocol which carefully exploits a combination of spatial and channel diversity to eliminate the need for performing expensive channel estimation in advance. By exploiting multiple routes over multiple channels, packets can be reliably communicated to the sink even in severely interfered environments.

Experimental research in low-power wireless networking lacks a reference benchmark. While other communities such as databases or machine learning have standardized benchmarks, our community still uses ad-hoc setups for its experiments and struggles to provide a fair comparison between communication protocols. Reasons for this include the diversity of network scenarios and the stochastic nature of wireless experiments. Leveraging on the excellent testbeds and tools that have been built to support experimental validation, we make the case for a reference benchmark to promote a fair comparison and reproducibility of results. This abstract describes early design elements and a benchmarking methodology with the goal to gather feedback from the community rather than propose a definite solution.

Recently with a push towards "IoTification", the world foresees a sharp rise in the number of devices with wireless networking capabilities. It is inevitable to anticipate an enormous increase in both self and cross-technology interference leaving a very challenging wireless communication medium at one's disposal. Maintaining robust data transmission in this increasingly hostile 2.4GHz band without incurring significant additional energy consumption is a basic concern. Towards this end we propose a suite of protocols (Syncast and Oppcast) exploiting capture effect over multi-channels and a careful knit of spatio-temporal and channel diversity to provide robust data transmission for multiple communication paradigms (Collection and Dissemination).