18. Radio Propagation Models

This chapter describes the radio propagation models implemented in ns. These models are used to predict the received signal power of each packet. At the physical layer of each wireless node, there is a receiving threshold. When a packet is received, if its signal power is below the receiving threshold, it is marked as error and dropped by the MAC layer.

Up to now there are three propagation models in ns, which are the free space model^18.1, two-ray ground reflection model^18.2 and the shadowing model^18.3. Their implementation can be found in ~ns/propagation.{cc,h}, ~ns/tworayground.{cc,h} and ~ns/shadowing.{cc,h}. This documentation reflects the APIs in ns-2.1b7.