Reconfigurable OFDM Receiver for Next Generation Wireless Mesh

Date The final copy of this thesis has been examined by the signatories, and we find that both the content and the form meet acceptable presentation standards of scholarly work in the above mentioned discipline. Performance of current mesh networks suffer due to the lack of an intelligent physical layer. Research and development in higher layer protocols alone cannot reduce the latency and performance of next generation wireless networks. If such a physical layer was designed so that it minimizes the involvement of higher layer protocols when it comes to routing, then latency in wireless networks can be reduced significantly. The transceiver for such a physical layer should have the ability to selectively switch the incoming packets " on-the-fly " to a different part of the spectrum so that a full-duplex transmit-receive chain is possible. This is also facilitated by the use of orthogonal modulation techniques either using orthogonal codes (OCDM) or orthogonal frequencies (OFDM) for transmission. An intelligent PHY like the one mentioned above will also play an integral part when it comes to cooperative transport of packets using MIMO systems and exploiting the spatial diversity of multiple antenna systems. In this thesis a convincing solution to the above problem is presented which will open new avenues in the search for ultra low-latency mesh networks. A design and implementation of a 802.11a/g compatible physical layer transceiver has been proposed which also supports OFDMA and physical layer routing or Wormhole Routing by using decode-amplify-forward relaying. The thesis is comprised of three parts, (i) Design and implementation of 802.11a/g OFDM receiver in FPGA, (ii) Optimizing the receiver chain to include adaptation to frequency agile transmitters and (iii) Incorporating additional design features that enables the existing transceiver to work as intermediate relay with spectrum switching in a multi-hop wireless mesh network.