Medium Access Control Protocols for Wireless Sensor Networks: Design Space, Challenges, and Future Directions

Introduction

The pervasiveness, self-autonomy, and self-organization of low-cost, low-power, and long-lived WSNs (Karl & Willig, 2006; Ilyas & Mahgoub, 2006; Li X. Y., 2008; Misra, Woungang, & Misra, 2009; Sohraby, Minoli, & Znati, 2007; Tubaishat & Madria, 2003; Akyildiz & Varun, 2010) have brought a new perspective to the world of wireless communication. This domain is destined to play a vital role to our future ubiquitous world as it extends the reach of cyberspace into physical and biological systems. Coupled with sensing, computation, and communication into a single tiny device, WSNs are emerging as an ideal candidate for several daily-life applications, particularly in monitoring and controlling domains. Demands placed on these networks are expending exponentially with the increase in their dimensions. The development of new hardware, software, and communication technology, and continuous refinements of current approaches is also pushing this domain even further. Besides the development of new algorithms and protocols, many commercial hardware vendors are also engaged designing novel and efficient architectures for sensor nodes¹. Figure 1 shows some of the sensor nodes used for deployment, experiment, and evaluation of different WSN related applications, whereas Table 1 gives hardware details in terms of microcontroller, radio chip, and memory available to these platforms.

Figure 1.

Some of the common sensor platforms used by industrial and research organizations for several WSN related applications and testbed implementations. They differ from each other in processing, storage, and communication capabilities and are suitable for an application or the other.