I want to determine the number of packets lost due to fading in a wireless, adhoc network. I am using the Nakagami module to add fading into the simulation, and the simulation is using Agent Trace as well as Mac Trace.
The nodes in the simulation broadcast randomly, and the trace file tells me when a broadcast is sent, when a broadcast is received, and when a packet is dropped. My first question is, what does the 'D' dropped tag actually mean? Does dropping a packet mean that a node was attempting to send a message, but it couldn't find an opening on the channel, so it discarded the packet before it was ever sent; or does it mean that a node started to receive a packet and then stopped for some reason? (All of the dropped packets seem to have a 'COL' tag in the 4th field; I am assuming that this stands for collision, but are there other tags that go in this position?) My second question is, what can I tell about packets that disappear from the trace file? The transmission power and reception threshold are set up so that each node has a 500m broadcast range. In some cases every neighboring node in the 500m range receives the broadcast, but in most cases a couple nodes will not receive the message, but they also won't drop the message. Does this mean that the message 'faded', or what other reasons are there why these packs are lost. Are there some other trace file types I can look at that will help? Ideally I would like to be able to run a simulation and then have the statistics calculations spit out the number of packets lost, and be able to tell the percentages of packets lost due to collisions, fading, and any other sources of packet loss. Thank you for your time.
