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In DVB-T Single Frequency Networks (SFN) different emitters simultaneously transmit the same signal on the same frequency. These signals can be used for positioning, or to integrate GNSS in hostile environments, but SFN characteristics may induce a path ambiguity problem. This paper demonstrates two solutions for solving this problem: pseudorange comparison and Doppler aiding decision. Both methods...
While the frequency-selectivity of underwater acoustic channels motivates the use of orthogonal frequency division multiplexing (OFDM), the time-selectivity leads to large pilot overhead for channel estimation and Doppler effects that cause intercarrier interference (ICI). ICI can be estimated and mitigated using an appropriate channel model, but in turn leads to even further increased demand on pilot...
Although time-domain oversampling of the received baseband signal is common for single-carrier transmissions, the counterpart of frequency-domain oversampling is rarely used for multicarrier transmissions. In this paper, we explore frequency-domain oversampling to improve the system performance of zero-padded OFDM transmissions over underwater acoustic channels with large Doppler spread. We use a...
MIMO-OFDM has been actively studied for high data rate communications over the bandwidth-limited underwater acoustic (UWA) channels. Unlike existing receivers that treat the intercarrier interference (ICI) as additive noise, in this paper we deal with ICI explicitly together with the co-channel interference (CCI) due to parallel transmissions in MIMO-OFDM. The proposed receiver has the following components:...
Recently it has been shown that sparse channel estimation, implemented with orthogonal matching pursuit (OMP) and basis pursuit (BP) algorithms, has impressive performance gains over alternatives that do not take advantage of the channel sparsity, for underwater acoustic (UWA) communications. We in this paper compare the performance and complexity of three popular BP algorithms, namely l1_ls, SpaRSA,...
In this paper we propose a progressive receiver for orthogonal-frequency-division-multiplexing (OFDM) transmission over time-varying underwater acoustic (UWA) channels. The progressive receiver is in nature an iterative receiver. However, it distinguishes itself from existing iterative receivers in that the system model for channel estimation and data detection is itself continually updated during...
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