Improving Routing Performance Under the Fading Environment by Utilizing Position Information

Performance of mobile ad hoc networks (MANET) routing protocols may be greatly degraded due to involvement of weak links in the routes. One solution is to use directional antenna to improve link quality. The other is to less prefer weak links. In the experiments we found that even with the two methods the system performance is still limited in the presence of mobility and multipath fading due to the following facts: (1) beam scanning overhead and frequent beam variations, (2) route instability due to metric variation and false link breaks. Then we improve it by three schemes: (i) Calculate the antenna beam by position information, (ii) Calculate a stable link metric from the expectation value of received signal strength indication (RSSI). (iii) Avoid false link breaks. These schemes are suitable for the scenarios where both line of sight path and multipath fading exist. The experiment and simulation results indicate that the schemes can effectively reduces PER and improve throughput of AODV in the Rician fading situations.