Detailed OFDM modeling in network simulation of mobile ad hoc networks

Abstract

Abstract : Typical studies of mobile ad hoc networks (MANET) use network simulation for the performance evaluation of protocols running at high layers. The need for developing highly detailed device models for accurate network simulation is clear; detailed models for the device and the wireless channel are crucial for prediction of higher layer network protocol performance. However, current network simulators substitute accurate physical layer models with generic abstract models for simplicity and speed. One approach to bridge this gap is by integrating a MATLAB Simulink OFDM radio and channel model into QualNet, a scalable packet-level simulator. This technique effectively captures the effect of the radio propagation and device while still maintaining reasonable simulation execution time. Also, the results depict that detailed modeling is necessary in studying the performance of higher-level protocols when compared to an abstract physical layer model. For example, the performance of the Auto Rate Fallback algorithm sharply decreases as the network load increases and this effect is more gradual when the transmission data rate is fixed. The detailed model incorporates the effects of different combinations of physical layer variables, e.g., path loss, shadowing, multipath, Doppler fading, and delay spread for each individual transmission in the simulation. Since traditional abstract modeling methods oversimplify the aforementioned variables, this lead to erroneous higher layer results when compared against the detailed model where these effects are modeled and observable. Model detail fidelity and simulation time tradeoff analysis are studied and compared.