Marie-Paule Uwase

QoS-aware cross-layer mechanism for multiple instances RPL

In Low power and Lossy Networks (LNNs), routing has been considered as a main design and development challenge. This has led to the open design of the IPv6 routing protocol for LLNs called RPL. The protocol allows creating groups (instances) of multiple loop-free routing topologies over a physical network. The purpose of forming an optimized tree routing topology is to drive packets from the nodes to the collection point or sink which is the root of the tree. In this paper, we take advantage of extracted routing information to support high performance transmission of priority packets by proposing a QoS-aware cross-layer mechanism. The mechanism is explained and its performance is evaluated through simulation experiments. Simulation results show that the proposed mechanism provides high Packet Reception Ratio with low Packet Delivery Latency for priority traffic.

Poster Abstract: Outdoors Range Measurements with Zolertia Z1 Motes and Contiki

Practically useful outdoor transmission ranges have been determined experimentally for Zolertia Z1 motes running Contiki. Both internal and external antennas were tested. The analog and digital quality of the received signal as well as the packet delivery rate have been measured. The influence of transmission power, bushes and weather conditions have been explored. Internal antennas were excessively sensitive to orientation, while external antennas allowed reliable and rather stable communications over distances between motes of up to 150 m. Radio duty cycling was responsible for some, still partially unexplained, packet losses.

Demonstrating the Versatility of a Low Cost Measurement Testbed for Wireless Sensor Networks with a Case Study on Radio Duty Cycling Protocols

Today, Wireless Sensor Networks (WSNs) with open source operating systems still need many efforts to guarantee that the protocol stack succeeds in delivering its expected performance. This is due to subtle implementation problems and unexpected interactions between protocol layers. The subtleties are often related to the judicious choice of parameters, in particular those related to timing issues. As these issues are often not visible in simulation studies, this paper proposes a low-cost versatile measurement testbed and demonstrates its usefulness in measuring the performance of RDC protocols. We demonstrate how the testbed helped to identify bugs in the implementation of an RDC protocol.

Experimental Comparison of Radio Duty Cycling Protocols for Wireless Sensor Networks

The performances of three different asynchronous radio duty cycling protocols available in the Contiki lightweight operating system have been compared experimentally in view of their adoption in medium sized wireless sensor networks integrated in the Internet of Things. This study unveils some of the subtleties of those protocols, allowing an improved tuning of their parameters, as well as the identification of overlooked shortcomings and implementation flaws. To ensure fair comparisons default options have been unified and small implementation and design problems have been tackled. Besides the previously mentioned interventions, default values for parameters were kept. The results of the comparison can help designers of wireless sensor networks with their choices and guide designers of protocols to overcome some critical issues.

Experimental evaluation of message latency and power usage in WSNs

Different techniques for measuring packet delivery ratio, packet latency and power usage on single hop radio links have been developed. These techniques were tested with Zolertia Z1 motes running Contiki by measuring the performances of different radio duty cycling protocols using a range of radio wake-up rates and various levels of global radio traffic. Advantages and disadvantages of the different techniques are discussed and the feasibility of enhancing them for multihop networks is explored.