This paper compares performance of index modulation (IM) based OFDM to a more flexible version of OFDM, known as OFDM with multiple constellations (OFDM-MConst). To deliver the same spectral efficiency as in the IM-based OFDM, the OFDM-MConst employs different constellations in different subcarriers. The performance comparison between IM-based OFDM and OFDM-MConst is done for both cases of "no precoding" and "with precoding" of data symbols. Thanks to the multipath diversity gain achieved with precoding and enjoyed by all the information bits, the precoded-OFDM-MConst is shown to significantly outperform precoded-IM-based-OFDM systems over frequency-selective Rayleigh fading channels. References [1] Z. Liu, Y. Xin, and G. B. Giannakis, "Linear constellation precoding for ofdm with maximum multipath diversity and coding gains," IEEE Trans. grouping for OFDM with linear constellation precoding over multipath fading channels," IEEE Trans. Veh.

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Abstract-We wish to minimize the resources used for network coding while achieving the desired throughput in a multicast scenario. We employ evolutionary approaches, based on a genetic algorithm, that avoid the computational complexity that makes the problem NP-hard. Our experiments show great improvements over the sub-optimal solutions of prior methods. Our new algorithms improve over our previously proposed algorithm in three ways. First, whereas the previous algorithm can be applied only to acyclic networks, our new method works also with networks with cycles. Second, we enrich the set of components used in the genetic algorithm, which improves the performance. Third, we develop a novel distributed framework. Combining distributed random network coding with our distributed optimization yields a network coding protocol where the resources used for coding are optimized in the setup phase by running our evolutionary algorithm at each node of the network. We demonstrate the effectiveness of our approach by carrying out simulations on a number of different sets of network topologies.

For 0.95(Na0.5K0.5)NbO3–0.05BaTiO3 (0.95NKN-0.05BT) ceramics sintered at 1040–1075°C, abnormal grain growth occurred but the grain size decreased when the sintering temperature exceeded 1075°C. The dielectric constant (ϵ3T∕ϵ3), electromechanical coupling factor (kp), and piezoelectric constant (d33) were considerably increased with increasing relative density and grain size. Evaporation of Na2O deteriorated the piezoelectric properties by decreasing the resistivity. To minimize Na2O evaporation, specimens were muffled with 0.95NKN-0.05BT powders during the sintering. Improved piezoelectric properties of d33=225pC∕N, kp=36%, and ϵ3T∕ϵ3=1058 were obtained for specimen sintered at 1060°C for 2h with muffling.