Creating wireless multi-hop topologies on space-constrained indoor testbeds through noise injection

To evaluate routing protocols on a controlled indoor wireless testbed, the radio range must be compressed so that larger multi-hop topologies can be mapped into a laboratory-size area. We propose noise injection as a more flexible option than hardware attenuation and consider methods for mapping real world wireless network topologies onto the testbed. Our experimental results show that additive white Gaussian noise effectively reduces the radio range, without the need for hardware attenuation and careful shielding of wireless cards. We performed experiments for a free space propagation environment. By selecting node positions through an automated procedure, we were able to create a 5-node/4-hop string topology and a random partially connected 6-node topology in a 8m by 8m area with off-the-shelf IEEE 802.11 hardware.