WMTP - Wireless Modular Transport Protocol

Project Description: WMTP is a modular transport layer architecture for Wireless Sensor Networks (WSNs) that not only integrates and enhances the most common features but also adds new ones that are not commonly found in WSN transport protocols. Our current work aims to provide the following functions: data reliability, congestion control, weighted fairness, flow control, Quality-of-Service (QoS), throttling, and service discovery awareness.

Active Period: 2006-2007

Project Funding: EU IST CRUISE project

Project Motivation: Traditionally, WSNs were powered by application specific protocols that were designed, built, and used with the needs of a certain specific application in mind. But, with the recent surge in applications that rely on these networks, came a demand for new protocols that could fulfill the needs of a broader range of applications, thus relieving the application developers of the additional effort of developing the underlying network layers. Most of the currently existing protocols suffer from an ailment all too common in WSNs: most of these protocols were designed with the needs of a specific class of applications in mind, and are either not suitable or inefficient for most other purposes. Given the special constraints that define these networks, conventional network protocols tend to be either inefficient or impractical to implement, thus the need for a new variety of alternative protocols, tailored specifically for these networks.
Additionally, most transport protocols designed for reliability do not offer congestion control and vice-versa. The few protocols that do offer both of these features, in turn, come short in performance, when compared to other protocols that either just implement reliability or just congestion control. Fairness, on the other hand, is mostly associated with congestion control, but the protocols that follow this path don’t generally provide any reliability semantics.

GEMS contribution: This quick overview emphasizes the need for a new protocol that would seamlessly integrate all of the above mentioned functionality, alongside some new features not commonly found in this area, such as optionally integrated Service Discovery and Quality-of-Service (QoS). In order to fulfill this need we are developing a new transport protocol: WMTP – Wireless Modular Transport Protocol.
Through WMTP we are designing a modular architecture that not only integrates and enhances the most common features but also adds new ones that are not commonly found in WSN transport protocols. Our current work aims to provide the following functions:

  • Data reliability: a packet may be retransmitted in case of loss, thus providing an additional level of assurance that a packet will reach its destination;
  • Congestion control: Packet forwarding and generation is delayed in order to avoid congestion on bottleneck nodes;
  • Weighted fairness: All connections that are transmitting to a common sink share the available network resources, either in an equitable fashion, or using a weighted differentiation algorithm;
  • Flow control: A simple mechanism where the receiving node may regulate the rate at which the sending node generates data;
  • Quality-of-Service (QoS): WMTP allows the establishment and operation of connections with guaranteed service levels (e.g. maximum end-to-end delay, minimum throughput, etc.). WMTP proposes a QoS model where applications may specify not only the minimum but also the desired service levels, when applicable (e.g. a connection that requires at least 10 packets per second but would ideally use 20);
  • Throttling: The application may specify a maximum packet generation rate;
  • Service Discovery: WMTP provides a specialized interface for service discovery modules, thus enabling this kind of semantic during connection establishment.

GEMS team: Luis David Pedrosa


  • Luis Pedrosa; "WMTP: Wireless Modular Transport Protocol", Master's Thesis, Instituto Superior Técnico / Technical University of Lisbon, November, 2007 (Awarded the Professor Luís Vidigal Award 2006 / 2007, for the best M.Sc. Thesis within the Electrical Engineering and Computer Science scientific areas at the Instituto Superior Técnico / Technical University of Lisbon)

Source code for TinyOS 2.x: TinyOS 2.x Contributions CVS Repository

Source code for TinyOS 1.1.x: WMTP-1.0.tar.gz