Average SER Analysis for Layered Division Multiplexing System with Index Modulation

Performance study of wavelength diversity serial relay OFDM FSO system over exponentiated Weibull channels

Orthogonal frequency-division multiplexing (OFDM) with index modulation has been emerged as a promising technique for next-generation networks, where the specific activation pattern of the OFDM subcarriers is capable of conveying additional information implicitly without additional energy consumption, hence improving the system energy efficiency. In this paper, zero-padded tri-mode OFDM with index modulation (ZTM-OFDM-IM) is proposed, which is capable of achieving high spectral and energy efficiency. In ZTM-OFDM-IM, subcarriers are partitioned into subblocks. In each OFDM subblock, only a fraction of subcarriers are modulated by two distinguishable constellation alphabets, while the others remain empty, which reduces the energy consumption. With such an arrangement, extra information bits can be carried by the subcarrier activation pattern. At the receiver, a maximum-likelihood (ML) detector as well as a reduced-complexity two-stage log-likelihood ratio (LLR) detector are developed for signal demodulation. Theoretical performance analysis based on Euclidean distance metric and pairwise error probability are conducted. Besides, in order to attain better BER performance, the design strategies for the two distinguishable constellation alphabets are investigated, which is followed by brief discussions on generalization methods for the proposed ZTM-OFDM-IM. It is demonstrated via Monte Carlo simulations that ZTM-OFDM-IM is capable of enhancing the BER performance compared with the conventional OFDM and other conventional index-modulated OFDM benchmarks, which provides high-rate data transmission with low energy consumption. Moreover, the LLR detection of ZTM-OFDM-IM only suffers from slight performance loss in comparison with the ML detection and achieves significant complexity reduction.

This paper presents Layered Division Multiplexing (LDM), a technology that may be used to provide a flexible multi-layer system transmission by means of spectrum overlay. This technology can be used to simultaneously deliver multiple program streams with different characteristics and robustness for different services (mobile TV, HDTV and UHDTV) in one RF channel. — In Layer Division Multiplex (LDM) the signal to be transmitted consists of a number of different independent signals superimposed together at different injection levels to form a multi-layer signal. Each layer can have its own characteristics. The top layer is the most robust one, which has a negative Signal to Noise Ratio (SNR) system threshold value, and can be used for robust mobile service. The lower layer(s) can be used to provide fixed high data rate services, such as multiple High Definition Television (HDTV) and Ultra High Definition Television (UHDTV). For example, DVB-T2, or an alternative design of a high data rate transmission system can be used for the second layer. The upper layer signal can be a separate program, or be used for delivering supplementary bit rate to be combined with the lower layer signal to provide additional features or achieve higher quality of service (e.g., scalable video coding and placing audio on upper layer for extra robustness).

The recommended bit rate (RBR) is assigned by gNodeB to the user equipment (UE) using MAC control element (CE) entity to provide bit rate information in 5G New Radio (NR). At the UE, the bit rate information is passed on to the upper layers; i.e., transport or application, for a specific logical channel either in uplink or downlink. However, based on specific application rate of target, UE does not know how to efficiently utilize and distribute RBR/throughput in lower and upper layer, respectively considering the specific logical channel. To address these problems, we propose a cross layer rate adaptation (CLRA) mechanism for UE. CLRA consists of two parts. In the first part, CLRA utilizes RBR received from gNodeB to compute throughput at lower layer. In the second part, CLRA distributes the throughput in upper layer received from lower layer based on specific applications rate of target. CLRA provides an intelligent mechanism to distribute throughput among foreground/ background applications and voice over internet protocol (VoIP) application considering a learning based codec adaptation. We conduct experiments with Samsung Galaxy S8 device and simulations to validate CLRA mechanism for applications in 5G NR.

Toner charge distributions in corona charged toner layers on a grounded metal plate were investigated. The charge distributions were measured through image analysis of the toner particles displaced onto a filter, depending on their charge to diameter ratio, after being blown off from the toner inlet into an electric field and dispersed. It has been confirmed that the toner charge distributions became broader by corona charging. In order to clarify the cause, dual toner layers have been formed by using different color toners, and the charge distributions at the upper and lower layers have been measured separately. The results show that the lower toner layer has a wider charge distribution than that of the upper layer. This result is attributable to the fact that the lower parts of the toner layer are covered with the upper toner layer and difficult to corona charge. The toner particles in the lower layer located at the opening of the overlapped upper layer tend to be highly corona charged, while the toner particles around the opening in the upper layer receive only a small amount of the corona charge. It has thus been shown that difference in charge distribution between the upper and lower parts of the toner layer is caused by the following mechanisms: 1) The toner particles at the lower part of the layer are shielded from corona charging ions by the upper layer; 2) The toner particles in the lower layer, which are located at the opening of the charged particles in the upper layer, receive more charging ions by concentration of the electric field; 3) The toner particles at the upper layer receive fewer charging ions because of higher electric potential owing to a longer distance from the grounded plate.

On days with clear skies in late August 2002 diurnal changes in the within-branch heterogeneity of photosynthetic photon flux density at the leaf surface (PPFDs) and leaf temperature (T leaf) were measured at natural leaf orientations in the upper and lower layers of a Fagus crenata crown. The PPFDs and T leaf measurements were converted to branch photosynthesis rates (P B; μmol s−1) using a photosynthetic model proposed by Farquhar et al. (Planta 149:78–90, 1980), an empirical stomatal conductance model suggested by Leuning et al. (Plant Cell Environ 18:339–335, 1995), and the total leaf area of the branches. To evaluate the importance of the variation in PPFDs and T leaf on photosynthesis calculations, P B calculated with the observed variation in PPFDs and T leaf was compared with estimates, based on the average (variation-free) values of PPFDs and T leaf, respectively. In both the layers, daily total P B values obtained with T leaf averaging were very close to those obtained with no averaging because of the weak inflection of the net photosynthesis rate (P n) to T leaf curves in the observed T leaf ranges (24.4–36.5 and 21.9–29.1°C in the upper and lower layers, respectively) and relatively small variation in within-branch T leaf at each time of day. This finding applied across potential climate conditions on fine days in August (T leaf range of 19.4–41.5 and 16.9–34.1°C in the upper and lower layers, respectively) and when the spatial scale was increased from branch to leaf layer, which increased the maximum variation in within-branch T leaf from 7.8 to 9.5°C and 4.5 to 5.5°C in the upper and lower layers, respectively. In contrast, averaging PPFDs caused 25–50% and 41–90% overestimation of daily total P B in the upper and lower layers, respectively, due to the sharp curvature in the PPFDs response curve to P n, and relatively large variation in within-branch PPFDs. Further, it led to overestimation of midday depression of P B in the upper layer, possibly because branch structural acclimation to incident light was neglected. Our results indicate that averaged values of T leaf could be used for the estimation of carbon gain at layer scale throughout August, but spatial variations in PPFDs need to be considered in detail for reliable estimates of carbon gain.

Early visual experience is essential for the maturation of visual functions in which the primary visual cortex plays crucial roles. The extraction of visual features based on response selectivity of individual neurons, a fundamental process in the cortex, is basically established by eye opening in rodents, suggesting that visual experience is required for the development of neural functions other than feature extraction. Here, we show that synchronized firing, which is important for visual information processing, occurs selectively in adjacent neurons sharing similar orientation or spatial frequency preferences in layers 2-4 (upper layer) of rat visual cortex. This feature-selective spike synchrony was rudimentary when the eyes opened and became prominent during the first few weeks after eye opening only in the presence of pattern vision. In contrast, synchronization in layers 5-6 (lower layer) was almost independent of orientation similarity and more weakly dependent on spatial frequency similarity compared with upper layer synchrony. Lower layer synchronization was strengthened during development after eye opening independently of visual experience as a whole. However, the feature selectivity of synchronization was regulated by visual inputs, whereas the inputs without contours were sufficient for this regulation. Therefore, we speculate that feature-selective synchronization in the upper layer may convey detailed information on visual objects to the higher-order cortex, whereas weakly feature-selective synchronization in the lower layer may covey rather rough visual information to the subcortical areas or higher-order cortex. A major role of visual experience may be to establish the specific neural circuits underlying highly feature-selective synchronization.SIGNIFICANCE STATEMENT The neuronal mechanisms underlying experience-dependent improvement of visual functions still remain unresolved. In this study, we investigated whether early visual experience contributes to the development of synchronized neural firing in the primary visual cortex, which plays important roles in visual information processing. We found that synchronized firing depends more remarkably on the similarity of preferred visual stimuli in the upper than lower layer neurons. Pattern vision during development was required for the establishment of spike synchrony in the upper but not the lower layer. These findings provide a new view regarding the role of sensory experience in the functional development of the cortex and the differences in the modes of information processing in the upper and lower cortical layers.

Solubility of magnesium hydrogen l-aspartate was examined. This salt is very easily soluble in water but hardly dissolves in organic solvents. In a mixture of water and organic solvents miscible with water, such as methanol, ethanol, propanol, and acetone, the salt distributes between the two layers, forming a dilute solution of the salt in the upper layer and a concentrated solution in the lower layer. The solubility of the slat in the upper layer increases exponentially with the molar fraction of water in the upper layer and the solubility is not affected by temperature. Analysis was carried out on the propanol-water-aspartate system in the upper and lower layers, three-componental phase diagram was prepared, and the Plait point, at which the upper and lower layers agreed, was calculated. It was also found that the exponential function established between the solubility in the upper layer and molar fraction of water thereof is also applicable to the lower layer.

In this paper, a group pre-coding scheme is proposed for multimedia broadcast multicast service (MBMS) downlink transmission in distributed multiple input multiple output (D-MIMO) antenna system. The ideal channel state information (CSI) is assumed to know at both transmitters and receivers. In order to evaluate the performance of the group pre-coding, the average symbol error rate (SER) of the Block Diagonalization - Minimum Mean Square Error (BD-MMSE) and Block Diagonalization - Zero forcing (BD-ZF) algorithms with group pre-coding in both D-MIMO and centralized MIMO (C-MIMO) system are investigated through Monte Carlo simulation. The SER performance of conventional pre-coding schemes with BD-MMSE is also given for comparison. The simulation results show that the degradation in SER performance of group pre-coding proposed is slightly comparing with that of the conventional pre-coding scheme, but the computational complexity of group pre-coding scheme is reduced significantly.

This paper analyzes the performance of a low complexity detector for orthogonal frequency multiplexing (OFDM) with index modulation (IM) over generalized fading channels. Novel closed-form expressions for the exact and approximate average pairwise error probability (PEP) and symbol error rate (SER) for OFDM-IM with greedy detector (GD) over κ−μ fading are derived. The moment generating function (MGF) approach is used to develop an accurate framework for a unified error performance analysis of OFDM-IM over a wide range of fading channels that describe fading conditions within classical and non-conventional propagation environments. The presented results provide a useful insight into the performance of OFDM-IM for a variety of emerging wireless machine type communication (MTC) systems including device-to-device (D2D), vehicle-to-vehicle (V2V), and body centric communication systems.

A two‐layer model with a rigid lid and a flat bottom on an f plane is employed to study a flow field driven by a density flux through the sea surface or the coast; for example, freshwater discharged from a river. The negative (positive) density flux into the upper layer is represented by the water beneath (over) the interface changing from the lower (upper) layer to the upper (lower) layer, that is, entrainment of the lower (upper) layer by the upper (lower) layer. The subinertial flow pattern constrained by the coast has two components: one is a baroclinic eddy nearby that matches the entrainment region, and the other is a forced, internal Kelvin wave along the appropriate half of the coast.

Due to its low out‐of‐band emission and high spectral efficiency, the generalized frequency division multiplexing (GFDM) has been adopted as one of the most prominent waveform techniques for the 5G networks. To further combat the deep fading, the space time coding (STC) can be integrated with the GFDM system which provide high diversity gain that results into low symbol error rate at the receiver. In this article, a generalized model of space time coded GFDM system (STC‐GFDM) has been proposed. More precisely, a comprehensive analytical framework to compute the average symbol error rate (ASER) is introduced, which can be used for any MIMO configuration, code rate, and arbitrary fading channel. The proposed framework has wider applicability over generalized fading channels and having more accurate exact solution along with easy to evaluate approximate solution. Thus, the proposed framework extends the horizon of performance analysis of STC‐GFDM system over any fading scenario, that is not covered so far in the literature. In general, the closed from expressions of exact and approximate along with asymptotic ASER are derived for different fading channels using moment generating function (MGF) approach. Particularly, the ASER analysis has been performed analytically using derived expression over Rayleigh, TWDP, Nakagami‐q, and Nakagami‐m fading channels for‐ary quadrature amplitude modulation (‐QAM). This analysis confirms that with the increase in transmit and receive antenna and decrease in modulation order, the ASER performance improves for all fading channels. Also, the improvement in ASER is observed as the power of specular components (ie, LOS paths) increases. Furthermore, these analytical results are validated using Monte‐Carlo simulation.

<p>Anisotropy in the Earth’s upper mantle is a signature of past and present deformation. Sri Lanka comprises four main lithological units, viz. the Highland Complex (HC), the Wanni Complex (WC), the Vijayan complex (VC) and the Kadugannawa complex (KC). To calculate the upper mantle anisotropy, we have collected the earthquake data from IRIS (Incorporated Research Institutions for Seismology) network. The upper mantle anisotropy beneath Sri Lanka is measured in the frequency band 0.01–0.15 Hz, with magnitude (Mw) of six or more and within the epicentral distance of 90°-140°. We have analyzed (the fast direction and delay time) shear wave splitting of SKS/SKKS phases at 3 stations, namely, MALK (WC), HALK (HC) and PALK (KC) in Sri Lanka. In this study, shear wave splitting measurements were done using high-quality seismograms (~30) of many earthquakes occurring in the region. We have used rotational correlation (RC) , minimum energy (SC) and eigenvalue techniques. The result of the shear-wave splitting measurement shows the presence of two anisotropic layers in the upper mantle. The upper and lower layer’s fast-polarization direction is found to be NE-SW and NW-SE, has the delay time varies from 0.4-0.5s in the upper layer, and 0.6-0.8s in the lower layer. We found two major fast directions in the upper and lower layers, viz. NE-SW in the upper layer of MALK and PALK and NW-SE for the HALK stations, and NNE-SSW in the lower layer beneath MALK and HALK stations and NW-SE in the PALK station. Overall, Fast direction for Sri Lanka region is found to be NE-SW in the lower layer and NW-SE in the upper layer. Our study suggests that fast axis direction of lower layer with an average delay time of 0.6 s depicts a ~67 km thick anisotropic layer with 4% anisotropy (from previous studies) beneath Sri Lanka region. However, if we assume an anisotropy range of 3–5%, then the calculated delay time of 0.6 s would correspond to thickness variation of 89.3 to 53.59 km, respectively, for the inferred anisotropic layer. Comparing from APM (Absolute Plate Motion) direction with our fast directions, we infer that the SAF(Simple Asthenospheric Flow) model prevails in this region and secondly, when S<sub>hmax </sub>(Maximum Horizontal stress) and the GPS (Global Positioning System) data compared with the fast direction we infer that there is partial contribution from lithospheric mantle. So, we confirmed that anisotropy in the region is mainly governed by asthenospheric flow and partially due to lithospheric mantle.</p>

Priming effect is one of the important mechanisms regulating soil organic matter decomposition. However, the variation of priming effects in different soil layers remains unclear. In this study, we conducted a 30-day incubation experiment using no-tillage black soil from northeastern China. 13C-glucose and dynamic CO2 trapping methods were employed to investigate soil organic carbon (SOC) mineralization rates and the priming effect of the added 13C-glucose in the upper soil layer (0-10 cm) and the lower soil layer (30-40 cm). Our results showed that the cumulative SOC-specific mineralization rate in the upper layer was similar to that in the lower layer soil without glucose addition. Glucose addition significantly altered the mineralization rates in both layers, resulting in a positive priming effect (36.7%) in the upper layer but a negative priming effect (-12.4%) in the lower layer. The cumulative priming effect during the 30-day incubation was 3.24 mg C·g-1 SOC for the upper layer soil and -1.24 mg C·g-1 SOC for the lower layer soil. There was still a net SOC increase, even with positive priming effects in the upper layer soil. This was due to considerable amount of added glucose-C remained un-mineralized in the soil which would compensate the carbon loss from priming effects. Overall, our results demonstrated that the magnitude and direction of priming effects might differ between soil layers. Our findings contribute to a better understanding of the effects of conservation tillage practices (no-tillage and straw incorporation) on soil organic matter dynamics in agroecosystems.

We have succeeded in generating B cell colonies from freshly separated human peripheral blood by the double agar layer technique and expanding them in liquid culture for several weeks. Populations of cells enriched in B cells were placed into the upper layer with or without bacterial LPS. Although B cell colonies were observed without LPS, the addition of LPS to the cells in the upper agar layer increased the number of colonies. Also necessary for optimal B cell colony formation was the presence in the lower agar layer of either culture supernatant of PHA-stimulated mononuclear cells or purified T cells and PHA. Without such helper factors in the lower layer, only a few B cell colonies were observed in the upper layer. By using these techniques, peripheral blood lymphocytes from normal individuals and patients with active systemic lupus erythematosus (SLE) were studied for the generation of B cell colonies. Significantly more B cell colonies were observed in patients with SLE, using either kind of "helper" factor. In addition, T cells from normal individuals and patients were tested for their ability to help B cell colony formation. The SLE T cells were found to be defective in this function relative to normal T cells. Thus, although patients with SLE were hyperactive in forming B cell colonies, thier T cells were defective in supporting the formation of B cell colonies from normal individuals.