Relevant Logics Obeying Component Homogeneity

This paper discusses three relevant logics that obey Component Homogeneity - a principle that Goddard and Routley introduce in their project of a logic of significance. The paper establishes two main results. First, it establishes a general characterization result for two families of logic that obey Component Homogeneity - that is, we provide a set of necessary and sufficient conditions for their consequence relations. From this, we derive characterization results for S*fde, dS*fde, crossS*fde. Second, the paper establishes complete sequent calculi for S*fde, dS*fde, crossS*fde. Among the other accomplishments of the paper, we generalize the semantics from Bochvar, Hallden, Deutsch and Daniels, we provide a general recipe to define containment logics, we explore the single-premise/single-conclusion fragment of S*fde, dS*fde, crossS*fdeand the connections between crossS*fde and the logic Eq of equality by Epstein. Also, we present S*fde as a relevant logic of meaninglessness that follows the main philosophical tenets of Goddard and Routley, and we briefly examine three further systems that are closely related to our main logics. Finally, we discuss Routley's criticism to containment logic in light of our results, and overview some open issues

FDE-vdW: A van der Waals Inclusive Subsystem Density-Functional Theory

We present a formally exact van der Waals inclusive electronic structure theory, called FDE-vdW, based on the Frozen Density Embedding formulation of subsystem Density-Functional Theory. In subsystem DFT, the energy functional is composed of subsystem additive and non-additive terms. We show that an appropriate definition of the long-range correlation energy is given by the value of the non-additive correlation functional. This functional is evaluated using the Fluctuation-Dissipation Theorem aided by a formally exact decomposition of the response functions into subsystem contributions. FDE-vdW is derived in detail and several approximate schemes are proposed, which lead to practical implementations of the method. We show that FDE-vdW is Casimir-Polder consistent, i.e. it reduces to the generalized Casimir-Polder formula for asymptotic inter-subsystems separations. Pilot calculations of binding energies of 13 weakly bound complexes singled out from the S22 set show a dramatic improvement upon semilocal subsystem DFT, provided that an appropriate exchange functional is employed. The convergence of FDE-vdW with basis set size is discussed, as well as its dependence on the choice of associated density functional approximant

Flexible Multi-Group Single-Carrier Modulation: Optimal Subcarrier Grouping and Rate Maximization

Orthogonal frequency division multiplexing (OFDM) and single-carrier frequency domain equalization (SC-FDE) are two commonly adopted modulation schemes for frequency-selective channels. Compared to SC-FDE, OFDM generally achieves higher data rate, but at the cost of higher transmit signal peak-to-average power ratio (PAPR) that leads to lower power amplifier efficiency. This paper proposes a new modulation scheme, called flexible multi-group single-carrier (FMG-SC), which encapsulates both OFDM and SC-FDE as special cases, thus achieving more flexible rate-PAPR trade-offs between them. Specifically, a set of frequency subcarriers are flexibly divided into orthogonal groups based on their channel gains, and SC-FDE is applied over each of the groups to send different data streams in parallel. We aim to maximize the achievable sum-rate of all groups by optimizing the subcarrier-group mapping. We propose two low-complexity subcarrier grouping methods and show via simulation that they perform very close to the optimal grouping by exhaustive search. Simulation results also show the effectiveness of the proposed FMG-SC modulation scheme with optimized subcarrier grouping in improving the rate-PAPR trade-off over conventional OFDM and SC-FDE.Comment: Submitted for possible conference publicatio

Enhanced MMSE FDE to Mitigate Multiuser Interference in MC-CDMA System

Carrier Frequency Offset (CFO) occurs due to asynchrony between transmitter and receiver local oscillator, and/or due to Doppler Effect that is caused by high mobility. Due to CFO, the orthogonality between subcarriers can be disrupted. In the uplink system, different carrier frequency offsets of different users at the receiver resulting multiuser interference (MUI), thus degrade the performance of MC-CDMA system. In the previous study, Modified Minimum Mean Square Error Frequency Domain Equalization (Modified MMSE FDE) has been proposed by Agnihotri which results in a better performance than the conventional MMSE. However, the achieved Bit Error Rate (BER) is not smaller than 10-2 for Signal to Noise Ratio (SNR) below 20. This research design a new algorithm in Multi-carrier Code Division Multiple Access (MC-CDMA) receiver side to mitigate MUI, that is called Enhanced MMSE FDE. Enhanced MMSE FDE is a modification of Modified MMSE-FDE to improve the system performance. Enhanced MMSE FDE takes into account the rest of MUI as well as Modified MMSE FDE to design FDE coefficient, but Enhanced MMSE FDE use CFO estimation that is not on Modified MMSE FDE. The value of CFO is estimated and regenerated in the receiver and then used to estimate MUI. MUI is assumed to be reconstructed and eliminated from the received signal. In order to get signal processing more efficient, Enhanced MMSE FDE takes only the real trace of FDE matrix. The simulation result shows that MC-CDMA with Enhanced MMSE FDE using Binary Phase Shift Keying (BPSK) and 64 subcarriers with 4 users gives better performance than MC-CDMA with Conventional MMSE and Modified MMSE FDE that have been performed by Agnihotri. However, the complexity of Enhanced MMSE FDE that takes the whole of FDE coefficient matrix is higher than Modified MMSE FDE. By taking only the real trace of FDE coefficient matrix, complexity of Enhanced MMSE FDE is getting simpler than taking the whole of FDE coefficient matrix. Furthermore, Enhanced MMSE FDE that takes only the real trace of FDE coefficient matrix is 2.93 % more efficient than Enhanced MMSE FDE that takes the whole of FDE coefficient matrix. Keyword-multiuser interference, Enhanced MMSE FDE, MC-CDMA