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Radar Waveforms
Published in Hai Deng, Zhe Geng, Radar Networks, 2020
The orthogonal transmit signals for co-located MIMO radar may be designed with binary-coding, polyphase coding, or frequency-hopping coding. Considering that polyphase sequences have better autocorrelation properties than the binary sequences and the frequency-coded sequences, a novel algorithm was proposed in Deng (2004) to numerically optimize the orthogonal polyphase code sets by using the simulated annealing algorithm. The simulation results show that the optimized polyphase sequences obtained in Deng (2004) have low aperiodic autocorrelation sidelobe peaks and low aperiodic cross-correlation energies. Later, a new set of polyphase sequences was presented in Khan et al. (2006) with the Doppler-shift effect taken into consideration. However, as pointed out in Deng (2012), since the Doppler-shift tolerant orthogonal coding signals are achieved by imposing additional structural constraints on the optimization problem, it may result in increased autocorrelation sidelobe levels and the cross-correlation energies as a performance trade-off. In Maio and Lops (2007), space-time coding (STC) for co-located MIMO radar was considered, and the codes were optimized under two different criteria: (1) the Chernoff bound and (2) the maximization of the mutual information between received signals. In Li and Stoica (2007), the probing signal for co-located MIMO radar was designed to (1) approximate a desired transmit beampattern and (2) minimize the cross-correlation of probing signals at a number of directions of interest. In Liu et al. (2014), sequential optimization was employed in to jointly design the transmit beamforming correlation matrix and the receive beamforming vector to suppress the interferences and maximize the signal-to-interference-plus-noise ratio (SINR). The sequential optimization approach proposed in Liu et al. (2014) was later modified and applied to the active–passive radar in Gao et al. (2017), which consists of a co-located MIMO radar and multiple illuminators of opportunity.
Evaluation of SINR Prediction in Cellular Networks
Published in IETE Technical Review, 2018
Enrique R. Bastidas-Puga, Guillermo Galaviz, Ángel G. Andrade
In cellular networks, the signal-to-interference-plus-noise ratio (SINR) is a quantity that indicates if a given frequency resource is suitable to properly maintain a communication link. This is why the level of SINR is used by the network to monitor the occurrence of radio link failures and handover failures [1]. Additionally, the SINR restricts the maximum data rate that can be achieved in a certain bandwidth for a given error rate [2]. Hence, in systems that use multiple access technology based on frequency division, the level of SINR can be considered by the scheduler in order to allocate frequency resources [3].