Generalized Spatial Modulation in Large-Scale Multiuser MIMO Systems

Generalized spatial modulation (GSM) uses $n_t$ transmit antenna elements but fewer transmit radio frequency (RF) chains, $n_{rf}$. Spatial modulation (SM) and spatial multiplexing are special cases of GSM with $n_{rf}=1$ and $n_{rf}=n_t$, respectively. In GSM, in addition to conveying information bits through $n_{rf}$ conventional modulation symbols (for example, QAM), the indices of the $n_{rf}$ active transmit antennas also convey information bits. In this paper, we investigate {\em GSM for large-scale multiuser MIMO communications on the uplink}. Our contributions in this paper include: ($i$) an average bit error probability (ABEP) analysis for maximum-likelihood detection in multiuser GSM-MIMO on the uplink, where we derive an upper bound on the ABEP, and ($ii$) low-complexity algorithms for GSM-MIMO signal detection and channel estimation at the base station receiver based on message passing. The analytical upper bounds on the ABEP are found to be tight at moderate to high signal-to-noise ratios (SNR). The proposed receiver algorithms are found to scale very well in complexity while achieving near-optimal performance in large dimensions. Simulation results show that, for the same spectral efficiency, multiuser GSM-MIMO can outperform multiuser SM-MIMO as well as conventional multiuser MIMO, by about 2 to 9 dB at a bit error rate of $10^{-3}$. Such SNR gains in GSM-MIMO compared to SM-MIMO and conventional MIMO can be attributed to the fact that, because of a larger number of spatial index bits, GSM-MIMO can use a lower-order QAM alphabet which is more power efficient.Comment: IEEE Trans. on Wireless Communications, accepte

Low-Complexity Iterative Detection for Orthogonal Time Frequency Space Modulation

We elaborate on the recently proposed orthogonal time frequency space (OTFS) modulation technique, which provides significant advantages over orthogonal frequency division multiplexing (OFDM) in Doppler channels. We first derive the input--output relation describing OTFS modulation and demodulation (mod/demod) for delay--Doppler channels with arbitrary number of paths, with given delay and Doppler values. We then propose a low-complexity message passing (MP) detection algorithm, which is suitable for large-scale OTFS taking advantage of the inherent channel sparsity. Since the fractional Doppler paths (i.e., not exactly aligned with the Doppler taps) produce the inter Doppler interference (IDI), we adapt the MP detection algorithm to compensate for the effect of IDI in order to further improve performance. Simulations results illustrate the superior performance gains of OTFS over OFDM under various channel conditions.Comment: 6 pages, 7 figure

PACLITAXEL DISPOSITION STUDIES USING P-GP INHIBTOR & INDUCER BY SINGLE PASS INTESTINAL PERFUSION IN RATS

Objective: The present research work aims to study the intestinal transport of Paclitaxel and to predict its human intestinal permeability and fraction absorbed using SPIP Permeability Coefficient and the effect of P-gp modulators on Paclitaxel were observed in anaesthetized rats. Methods: Jejunal segment was used for performing Single Pass Intestinal Perfusion. The rationale for the selection of jejenum is due to the overexpression of P-glycoprotein when compared with other segments. Drug solution (150µg/ml) in phosphate buffer saline was perfused at a flow rate of 0.2ml/min.Besides,P-gp inhibitor verapamil(200 µg/ml) and inducer Rifampicin (60mg/ml) were coperfused with Paclitaxel to detect its disposition characteristics affected by P-gp .Drug concentrations in samples were analyzed using HPLC. Stability studies were conducted to ensure the loss of Paclitaxel due to absorption. Results: The effective permeability value of Paclitaxel (150µg/ml) in the jejunal segment was found to be lower due to the efflux mediated by P-gp.When coperfused with verapamil its permeability significantly enhanced as it is a P-gp inhibitor and vice versa with Rifampicin which is a P-gp inducer. Subsequently the human intestinal permeability was estimated considering Peff(human) =1.04 Peff(rat)-0.0003. Conclusion: P-Glycoprotein mediated drug resistance is one of the serious limitations of Paclitaxel efficacy and jejunal segment is found to have major MDR expression. The Peff value of Paclitaxel was found to be increased upon the Coperfusion with verapamil and similarly reduced with Rifampicin which are inhibitors & inducers respectively indicating Paclitaxel is efficiently transported by P-gp. Hence, Paclitaxel satisfies all the prerequisites to be a P-gp substrate.   Keywords: Paclitaxel, Intestinal permeability, Single pass intestinal perfusion, P-glycoprotein, RP-HPLC

A Cost-Effective Fault Tolerance Technique for Functional TSV in 3-D ICs

Regular and redundant through-silicon via (TSV) interconnects are used in fault tolerance techniques of 3-D IC. However, the fabrication process of TSVs results in defects that reduce the yield and reliability of TSVs. On the other hand, each TSV is associated with a significant amount of on-chip area overhead. Therefore, unlike the state-of-the-art fault tolerance architectures, here we propose the time division multiplexing access (TDMA)-based fault tolerance technique without using any redundant TSVs, which reduces the area overhead and enhances the yield. In the proposed technique, by means of TDMA, we reroute the signal through defect-free TSV. Subsequently, an architecture based on the proposed technique has been designed, evaluated, and validated on logic-on-logic 3-D IWLS'05 benchmark circuits using 130-nm technology node. The proposed technique is found to reduce the area overhead by 28.70%-40.60%, compared to the state-of-the-art architectures and results in a yield of 98.9%-99.8%

Statistical experiment analysis of wear and mechanical behaviour of abaca/sisal fiber-based hybrid composites under liquid nitrogen environment

Ice accretion on various onshore and offshore infrastructures imparts hazardous effects sometimes beyond repair, which may be life-threatening. Therefore, it has become necessary to look for ways to detect and mitigate ice. Some ice mitigation techniques have been tested or in use in aviation and railway sectors, however, their applicability to other sectors/systems is still in the research phase. To make such systems autonomous, ice protection systems need to be accompanied by reliable ice detection systems, which include electronic, mechatronics, mechanical, and optical techniques. Comparing the benefits and limitations of all available methodologies, Infrared Thermography (IRT) appears to be one of the useful, non-destructive, and emerging techniques as it offers wide area monitoring instead of just point-based ice monitoring. This paper reviews the applications of IRT in the field of icing on various subject areas to provide valuable insights into the existing development of an intelligent and autonomous ice mitigation system for general applications