Prototyping a Highly Flexible Wireless Node for Cross-Layer Research

With funding and other assistance from the National Science Foundation, National Instruments, and Texas Instruments, three WNCG professors, Jeff Andrews, Robert Heath, and Scott Nettles along with Professor Kapil Dandekar of Drexel University and 11 of their students are constructing a prototype of a highly flexible wireless node for cross layer research.

It has become increasingly clear that the strict layering of current network architectures does not allow full exploitation of wireless communication. This has inspired a wealth of research into designs that cross the traditional network layers. Unfortunately, much of this research has depended on simulation to demonstrate the usefulness of the proposed approaches. Accurate cross layer simulations are very difficult to perform, especially with respect to wireless channel modeling. This new research endeavor aims to build a set of working wireless nodes that incorporate cutting edge physical layer techniques with a highly flexible network implementation, allowing the exploration of cross-layer designs with real hardware.

The implementation of the new prototype is divided into three chief components: the RF front-end, the PHY, and the MAC and higher-level networking services. The RF front-end work is lead by Professor Dandekar and is based on an 802.11abg front-end donated by TI. Analog baseband signals are converted to and from the digital domain by ADA boards from NI and become the inputs to or outputs from the PHY. Work on the PHY is lead by Professor Heath with assistance from Professor Andrews. The PHY itself is implemented in Labview running on a dedicated processor. The PHY will implement both Multiple Input Multiple Output (MIMO) antenna communications and Orthogonal Frequency Division Multiplexing (OFDM). Using MIMO/OFDM will provide a highly flexible physical layer that will allow maximum cross-layer experimentation. The implementation of the MAC and higher-level networking services is being lead by Professor Nettles, who is also coordinating the overall effort. The MAC runs on a separate node and communicates with the PHY via gigabit Ethernet. Its implementation is based on the Click Modular Router, which will provide the prototype with a "plug-and-play" framework for MAC and higher layer experimentation.