Experience with a wireless network testbed based on signal propagation emulation

Abstract

The evaluation of wireless research is challenging because signals traveling through the ether are affected by the physical environment, including movement by people and objects. As a result, testbed experiments are hard to control and are non-repeatable. We have developed a wireless networking testbed based on digital signal propagation emulation that provides control over the signal propagation environment. The testbed has been in regular use for research and education since early 2007. In this paper we present measurements illustrating the properties of the emulator testbed. We also compare the results of various experiments on the emulator with simulation results to shed some light on when the increased accuracy of the emulator testbed is important. Finally, we use the experience gained on the emulator to identify classes of experiments for which the emulator is well suited, compared with other evaluation platforms.

FPGA-Based Wireless Link Emulator for Wireless Sensor Network

“…The work presented in [18] is comparable to our work in the sense that they also use FPGA to replace the wireless media. However, there are three major differences: first at hardware level, they actually intercept the analog RF signal at the antenna port, while in our system, the data is never modulated into RF signal; secondly, in their work the FPGA is used to perform digital signal processing(DSP) based on a certain channel model, while in our system it is used to implement the radio interface and ring transceiver; Finally in essence, our system relies on the relationship between SNR and BER to achieve topology and interference control, while they rely on the physical layer channel model and DSP.…”

“…While for our system it is achieved by specifying parameters such as pathloss and noise level directly. The work presented in [18] is more suitable to emulate certain physical layer phenomena, while our system focuses more on general network performance. Also we believe our system is more userfriendly for researchers without DSP and physical layer background.…”

A Test Methodology for Evaluating Cognitive Radio Systems

“…The goal of this research is to investigate how real wireless devices behave in a controlled environment; therefore, the use of a hardware-based channel emulator (the second approach) is most appropriate. Existing hardware-based channel emulator testbeds include the CMU Emulator [15], WHYNET [14], BEE2 [12], and the DYSE [16].…”

Realistic Modeling of Wireless Network Environments

“…A first version of wireless emulator testbed was in regular use by both CMU and external users from 2007 until 2011 [7,8]. It supported the full 2.4 GHz ISM band and had 15 nodes.…”