Prof Mari Kobayashi - TU Munich and Centrale-SUPELEC Communication systems
Date: December 12th 2019 Location: Eurecom - Eurecom
We consider a communication setup where transmitters wish to simultaneously sense network states and convey messages to intended receivers. First, we present a theoretical framework to characterize the fundamental limits of such a setup for memoryless channels with i.i.d. state sequences. Inspired by its potential gain demonstrated in this theoretical framework, we consider a joint radar and communication system using Orthogonal Time Frequency Space (OTFS) in a point-to-point communication setup over multi-path time-frequency selective channels. We propose an efficient approximated Maximum Likelihood (ML) algorithm and the corresponding Cramer-Rao lower bound (CRLB) for range and velocity estimation. Our numerical examples demonstrated that OTFS provides as accurate radar estimation as Frequency Modulated Continuous Waveform (FMCW), a typical automotive radar waveform, while providing a non-negligible communication rate for free. We address the OTFS symbol detection at the receiver side. In particular, we consider a message-passing algorithm that efficiently exploits the channel sparsity in the Doppler-delay domain. The detection performance in terms of pragmatic capacity, i.e. the achievable rate of the equivalent channel whose input and output are the signal constellation and the detector soft output, respectively, shows that the proposed scheme outperforms the state-of-art. The talk is mainly based on our recent work https://arxiv.org/abs/1910.01896.