Tactical Wireless Communications and Networks: Design Concepts and Challenges

4.1 MAC Layer and Multiple Access Techniques

As you will see in Chapter 5 onwards, legacy tactical radios were (non-IP) implemented with static resource allocation techniques in order to manage access to the physical layer resources. Each node was designated a specific configuration, delineating when and how to use the physical layer resources, such that no interference occurred. The problem with static configuration is the poor utilization of the physical layer resources. This is especially problematic when traffic demand between nodes in the same subnet is dynamic and can vary drastically. With the move to IP-based tactical radios, dynamic resource allocation techniques for sharing the physical layers' resources had to be implemented at the MAC layer. While this chapter presents some of the challenges facing the design of MAC layer protocols, Chapter 5 onwards further explains the fundamentals of managing physical layer resources for tactical radios.

The protocol stack layering presented in Chapter 1, Figure 1.1, showed the MAC layer as a stand-alone layer (although some communications and networking books show the MAC layer as a DLL sub-layer). In tactical wireless networks, the MAC layer plays an important role in satellite communications and multiple access radio, where the physical layer resources are shared between multiple nodes. The separation of functions between the MAC, data link, and network layers is not as clear cut when it comes to multiple access tactical radios ...