SGER: Exploiting Motion in Wireless Networks

Purdue University, West Lafayette IN

Investigators

Abstract

This project focuses on the cross-layer design of wireless systems, at the network protocol, data link, and physical link layers. Mobility, which has traditionally been viewed as an impediment, can be utilized to improve the use of wireless spectrum. Significant gains in performance can be achieved by adding structure to transmitted signals and exploiting the different Doppler shifts of nodes in multi-carrier code-division multiple-access systems. Feedback among the lower three protocol layers offers the opportunity to utilize the frequency shifts that result from the motion of mobile wireless users, thereby alleviating effects of interference and increasing effective utilization. Intellectual Merit. This project introduces a novel way to exploit motion as an additional parameter in wireless systems. By utilizing frequency subbands as in OFDM and adding sufficient structure to transmitted signals for processing, Doppler frequency shifts can be used to reduce the effects of interference. Initial work by the investigators suggests the processing is feasible. The use of motion requires that the physical, data link, and network layer protocols be designed in an integrated fashion, and assumes that computing and location-awareness capabilities will continue to improve. The use of timing relationships between received signals for interference excision, which also requires cross-layer information, is also an increasingly feasible approach. Broader Impacts. This project initiates research into utilization of motion as a possibly beneficial factor in the optimization of wireless spectrum. The potential benefits of exploiting motion, instead of compensating for it, are very significant. This is analogous to the MIMO techniques that have gained such prominence in recent years, in that factors that were previously believed to be detrimental to performance are transformed into positives. Exploiting motion requires a cross-layer approach, as information on movement needs to be passed to lower layers to enhance processing at those layers. This research will help to understand the benefits of integrated design across layers. Further, this work will support graduate education into cross-layer techniques through the student positions included in the project plan.