Starting from the first years of this century wireless sensor networks (WSNs) have been envisaged as stand-alone networks that will allow us to collect and control information from our surroundings. However, only a decade later, they have turned into one of the main pillars of ubiquitous communications and today they have come to exhibit variety, complexity and numbers never envisaged before. From exotic applications, they have turned into commodities, and recently with the introduction of machine-to-machine (M2M) communications they are seen as one of the underlying technologies that will make the new reality. Because of the different operational paradigm and strongly application-oriented characteristics, WSN mandate the development of new network protocols quite different from the traditional open systems interconnection layered protocols. Furthermore, their enormous variety, continuously emerging new application possibilities and the need to optimize their performance have given rise to different sub-divisions of WSN - underground WSN, underwater WSN, etc. One newly defined area is WSN with linear topology. Since this topology presents both new challenges and new advantages network and medium access control (MAC) layer protocol design for these networks has become a hot research topic. In the light of these and taking into consideration the fact that many of the proposed M2M applications require linear topologies and this chapter introduces the details on linear wireless sensor networks (LWSNs) and specifically concentrates on the MAC protocols which play the most important role in optimizing their performance from energy and delay point of view. The chapter is organized as follows: first, the concept and terminology related to LWSN is introduced, and then their communication model and specifics are discussed, followed by a detailed overview of the most recent MAC protocols designed specifically for LWSN. The chapter is concluded with some open research issues.

Chapter Contents:

• Abstract
• 10.1 Introduction
• 10.2 Linear wireless sensor networks
• 10.2.1 Network model
• 10.2.2 Variations of LWSNs
• 10.2.2.1 Single line
• 10.2.2.2 Chain type
• 10.2.2.3 Chain tree
• 10.2.2.4 Hierarchical
• 10.2.3 Objectives and challenges of LWSNs
• 10.3 MAC protocols for LWSNs
• 10.4 Open research issues
• 10.5 Conclusion
• References
• Further reading
• List of abbreviations
• Glossary
• Biographies

Inspec keywords: access protocols; wireless sensor networks; telecommunication network topology; next generation networks

Other keywords: application-oriented characteristics; next-generation networks; M2M communications; LWSNs; ubiquitous communications; open systems interconnection layered protocols; network protocols; MAC layer protocol design; linear wireless sensor networks; medium access control layer protocol design; linear topology; machine-to-machine communications

Subjects: Wireless sensor networks; Protocols; Communication network design, planning and routing