Speaker: Dr. Alexander Fish (Sydney) http://www.maths.usyd.edu.au/u/afish/ Time: Friday, Oct. 26, 2:30--3:30PM Room: OMB-149, Old Main Building, UNSW Lunch with speaker: meet around 1PM at the entrance to the East Wing of Red Centre Building. One choice of commuting from Sydney: meet at Carslaw 620 around 12:25PM and share taxi to UNSW. The round trip is covered by school colloquium fund. ----------------------------------------------- Title: Heisenberg-Weil Representation and Delay-Doppler Channel Estimation in Wireless Communication. Abstract: A fundamental task in wireless communication is channel estimation: Compute the channel parameters a signal undergoes while travelling from a transmitter to a receiver. In the case of delay-Doppler channel, a widely used method is the matched filter algorithm. It uses a pseudo-random waveform of length N; and, in case of non-trivial relative velocity between transmitter and receiver, its arithmetic complexity is O(N^2 log(N)). We introduce a novel approach of designing waveforms that allow much faster channel estimation. Using Heisenberg-Weil representation we construct waveforms, which enable us to introduce a new algorithm, called the flag method, that significantly improves the matched filter algorithm. The flag method finds the channel parameters in O(mN log(N)) operations (In certain applications N >> 1000), for channel of sparsity m. We discuss applications of the flag method to mobile communication of fast moving users, and GPS. This is a joint work with Gurevich (UW-Madison),Hadani (UT-Austin), Sayeed (UW-Madison), and Schwartz (UC-Berkeley). ----------------------------------------------- Joint Colloquium web site: http://www.maths.usyd.edu.au/u/SemConf/JointColloquium/index.html