Topology Building for Multi-hop Wireless Networks Based on 802.11Ext Physical Layer in NS2

Transmission range, carrier sense range and packet loss are crucial problem in multi-hop wireless network simulations. We introduce the physical layer specification of 802.11 protocols and the energy-aware-based carrier sense model implemented by the physical layer in 802.11Ext of NS2. Especially we summarize the relationship between network simulation parameters and wireless multi-hop network topology to guide topology building work. To overcome the shortcomings of the existing threshold-based packet error model of the 802.11Ext module, we implement a SNR-based bit error model to simulate the real wireless signal propagation better. We verify the topology building method and the bit error model by simulations and trace file analysis.