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Internet of Medical Things (IoMT) connects different medical devices, health sensors and hospital records to data platforms using wireless communications. Federated Learning (FL) is an emerging collaborative learning technique that can be beneficial for IoMT due to reduced communication overhead and enhanced security. This paper provides an overview of different architectures used in FL and potential approaches for FL based IoMT. We also discuss how Physical Layer Security (PLS) can be used for efficient privacy preservation of data in FL based IoMT. We highlight the recent work in this area and major research challenges related to PLS assisted FL in IoMT. We also provide a case study demonstrating that clustering of IoMT devices (such that a single device in each cluster acts as a cluster head) enhances the secrecy rate of the FL based IoMT network as compared to its non-clustered counterpart. Finally, we also discuss future opportunities and open research questions related to PLS assisted FL in IoMT.

A multi-hop free space optical link based on all-optical relays is presented. All-optical relays are either composed of simple optical amplifiers or optical regenerators. It has been shown that after a certain number of hops, the amplifier based relay cannot extend the range of the free space optical link. Therefore, we have investigated the use of a self phase modulation based regenerator as a substitute for simple amplifier based relay. By employing the regenerative relay, a 10 Gbps optical signal having pulse width of 7 ps is transmitted over a distance of 8 km of free space optical link. The free space optical link is modeled on the basis of Gamma-Gamma channel model in the strong turbulence regime. The performance of the link is observed on the basis of bit error rate analysis. It has been shown that under strong turbulence and accumulation of amplifier noise, the range of the link can only be extended by employing an optical regenerator.

In this paper, we report the performance evaluation of praseodymium doped fiber amplifier (PDFA) operating in 1.25–1.35 μm band of wavelengths based on theoretical simulation. The performance of the PDFA is evaluated by considering an optimized length of Pr $$^{3+}$$ doped fiber, concentration of Pr $$^{3+}$$ ions and pump power. Moreover, the impact of input signal wavelength on gain, amplified spontaneous emission (ASE) noise and noise figure (NF) of the amplifier is also investigated. A small signal peak gain of around 22.7 dB is achieved at 1.3 μm for Pr $$^{3+}$$ doped fiber having short length of 15.7 m at an optimized pump power of 300 mW. A minimum NF of 4 dB is observed at 1.284 μm.

Broadband amplification in the O+E-band is very desirable nowadays as a way of coping with increasing bandwidth demands. The main issue with doped fiber amplifiers working in this band such as the bismuth-doped fiber amplifier is that they are costly and not widely available. Therefore, a wideband and flat-gain hybrid optical amplifier (HOA) covering the O+E-band based on a parallel combination of a praseodymium-doped fiber amplifier (PDFA) and a semiconductor optical amplifier (SOA) is proposed and demonstrated through numerical simulations. The praseodymium-doped fiber (PDF) core is pumped using a laser diode with a power of 500 mW that is centered at a wavelength of 1030 nm. The SOA is driven by an injection current of 60 mA. The performance of the HOA is analyzed by the optimization of various parameters such as the PDF length, Pr3+ concentration, pump wavelength, and injection current. A flat average gain of 24 dB with a flatness of 1 dB and an output power of 9.6 dBm is observed over a wavelength range of 1270–1450 nm. The noise figure (NF) varies from a minimum of 4 dB to a maximum of 5.9 dB for a signal power of 0 dBm. A gain reduction of around 4 dB is observed for an O-band signal at a wavelength of 1290 nm by considering the up-conversion effect. The transmission performance of the designed HOA as a pre-amplifier is evaluated based on the bit-error rate (BER) analysis for a coarse wavelength-division multiplexing (CWDM) system of eight on-off keying (OOK)-modulated channels, each having a data rate of 10 Gbps. An error-free transmission over 60 km of standard single-mode fiber (SMF) is achieved for different data rates of 5 Gbps, 7.5 Gbps, and 10 Gbps.

The performance of doped fiber amplifiers can be enhanced significantly with the help of multi-stage pumping technique provided that various critical parameters of pumps including their optical power and wavelength are optimized. We report the performance enhancement of a ytterbium doped fiber amplifier (YDFA) for a 1.02–1.08 μm spectral region with an optimized design based on a novel dual-stage in-band asymmetrical pumping scheme. By accurately adjusting the optical power and wavelength of pumps in both the stages, a record peak gain of around 62.5 dB and output power of 4.5 W are achieved for a signal wavelength of 1.0329 μm at an optimized length of Ytterbium-doped silica fiber and optimized doping concentration of Yb3+. Moreover, a minimum noise figure (NF) of 4 dB is observed for a signal wavelength of 1.0329 μm at the optimized parameters. Similarly, the effect of using high and low pump powers at the first and the second stage, respectively, on NF of the amplifier is also investigated at different values of signal powers. It is observed that the value of NF increases significantly by using high pump power at the first stage and low pump power at the second stage.

Nodes in a body area network (BAN) are miniature wearable or implantable battery-powered wireless sensors which continuously transmit real-time vital physiological data of a patient to remote health-care center while remaining in close proximity to the human body. Therefore, BAN nodes should have the features of high data rates and low transmit powers to protect the human body, environment and bio-medical equipment from harmful exposure of electromagnetic radiations and electromagnetic interference (EMI). Ultra-wideband (UWB) signals have low allowable transmission power and high data rates. Therefore, we propose a low cost, low powered and secure optical body area network (OBAN) composed of four UWB-BAN nodes each transmitting at a data rate of 30 Mbps. At the control node, UWB signals from UWB-BAN nodes are encoded using spectral amplitude coding-optical code division multiple access (SAC-OCDMA) scheme and the combined signal is transmitted over free space optics (FSO) channel towards remote health-care center. At the health-care center, the combined signal is decoded and UWB signal of each UWB-BAN node is photo-detected for analysis of patient’s data. Log-normal channel model is considered between control node and the health-care center. The signal received from each UWB-BAN after propagation through the FSO channel is analyzed through Bit error rate (BER) results. Similarly, cost efficiency of the proposed architecture is also evaluated through a detailed cost analysis. It was observed that the proposed architecture requires the UWB-BAN nodes to have low receiver sensitivities with the added benefits of cost-efficiency and data security.

In this letter, we present an intelligent reflecting surface (IRS) selection strategy for multiple IRSs aided multiuser multiple-input single-output (MISO) systems. In particular, we pose the IRS selection problem as a stable matching problem. A two stage user-IRS assignment algorithm is proposed, where the main objective is to carry out a stable user-IRS matching, such that the sum rate of the system is improved. The first stage of the proposed algorithm employs a well-known Gale Shapley matching designed for the stable marriage problem. However, due to interference in multiuser systems, the matching obtained after the first stage may not be stable. To overcome this issue, one-sided (i.e., only IRSs) blocking pairs (BPs) are identified in the second stage of the proposed algorithm, where the BP is a pair of IRSs which are better off after exchanging their partners. Thus, the second stage validates the stable matching in the proposed algorithm. Numerical results show that the proposed assignment achieves better sum rate performance compared to distance-based and random matching algorithms., Comment: 5 pages and 4 figures, submitted for publication

A free space optics based ring topology that transmits full‐duplex data to four different nodes in the ring is proposed. The link is designed such that the four nodes do not require a local optical source to transmit the uplink data. A wavelength division multiplexed signal composed of four different wavelengths each modulated by the downlink baseband data using differential phase shift keying is transmitted towards the nodes. At each node, the downlink baseband data is extracted and the received optical pulses are remodulated by the uplink baseband data using on‐off keying modulation format. Each node has a data rate of 10 Gbps and is at a distance of 400 m from the consecutive node. The free space optical link is modelled on the basis of Gamma‐Gamma channel model under different turbulence conditions by considering the refractive index structure parameter values of 5×10−15, 5×10−13 and 5×10−12m−2/3. Bit error rate results are obtained for both the downlink and uplink channels. Finally, power budget analysis is presented to demonstrate the robustness of the link under different weather conditions.

Optical signal regenerators are required at regular intervals in a long-haul optical link to re-amplify, re-shape and in some cases re-time the signal that has been distorted by the impairments of the link. A major benefit of all-optical regenerators is that they do not require the optical signal to be converted into the electrical domain for performing the above-mentioned tasks. This study analyzes the performance of our previously proposed optical signal regenerator along with two other regenerators that are based upon cross-phase modulation (XPM) and four wave mixing (FWM), respectively. The aim of the study is to determine the most suitable regenerator for a specific optical link based on its characteristics. The characteristics of the regenerators that are analyzed in this study include capability to reject noise, extinction ratio, reduction in timing jitter, chirp induced over the regenerated signal and energy yield of the regenerator. The analysis shows that each of the three regenerators have different capabilities that make them suitable for different optical links.

In this paper, we investigate channel estimation for a large intelligent surface (LIS) aided multiple-input multiple-output (MIMO) communication system. Due to the close proximity of communication devices and LIS terminal, the desired channels can be modeled as line-of-sight channels which are ill-conditioned. To estimate these channel matrices with high quality, we propose a two-stage channel estimation method. In particular, we employ the conventional time-division duplexing based MIMO channel estimation technique in the first stage to estimate the direct MIMO channel between the end terminals. In the second stage, we propose to use a recently developed bilinear adaptive vector approximate message passing (BAdVAMP) algorithm to estimate ill-conditioned LIS channels. The BAdVAMP method has been shown to be accurate and robust for ill-conditioned dictionary learning problems in compressed sensing. We also propose a phase shift design for the LIS using the estimated channels. Specifically, we formulate an optimization problem that maximizes the total channel gain at the user. A closed-form expression to obtain the phase shift of each passive element in the LIS is also derived. Numerical results show that the proposed BAdVAMP based LIS channel estimation performs better than its counterpart scheme bilinear generalized AMP (BiGAMP), especially when channel matrices are ill-conditioned., 10 pages, 7 figures

In this paper, we propose a cost-efficient single mode fiber-free space optics (SMF-FSO) based hybrid $$32 \times 2~\text{Gbps}$$ wavelength division multiplexed passive optical network (WDM-PON) employing optical frequency comb (OFC) source and polarization multiplexing. OFC source is realized at optical line terminal (OLT) by modulating a single continuous wave (CW) laser source with radio frequency (RF) sinusoidal signal and dual-drive Mach–Zehnder modulator (DD-MZM). 16 coherent optical carriers are used to split into 32 x and y-orthogonal polarization states which are used to transmit the on-off keying (OOK) data of 32 channels to remotely located optical network units (ONUs). The performance of the channels is analyzed with bit error rate (BER) plots employing Gamma–Gamma (GG) FSO channel model at different turbulence regimes and lengths of FSO link. Moreover, the effect of varying the polarization mode dispersion (PMD) on BER is also evaluated. The cost of the proposed architecture is analyzed and compared with conventional PON architecture. The cost efficiency of the proposed architecture is demonstrated by the use of a single CW laser source to transmit the data of 32 users between remote node (RN) and ONUs through FSO links having reduced installation and maintenance costs.

A reconfigurable and application-specific tunable microwave photonic filter having finite impulse response is proposed. The filter exploits the differential mode group delays of linearly polarized modes in a multi-mode fiber to achieve single and multiple high-frequency passband response. The filter taps are realized using a single continuous wave laser source and differential delays among modes that are propagated through a single spool of graded index multi-mode fiber. Depending upon the application requirement, different values of free spectral range of the microwave photonic filter are obtained by employing fiber spools of different lengths. The reconfigurability of the microwave photonic filter is achieved by varying the number of linearly polarized modes. It has been shown that the passband ripple can be reduced by employing higher order spatial modes and unequal power ratio among different modes. The proposed filter enables application-specific free spectra range tunability and reconfigurability along with added advantages of easy implementation and passband optimization.

We propose a novel technique to regenerate the optical signal in a relay-based free space optical link. Our proposed regenerator is based on an Electro-absorption modulator whose optical input is the signal to be regenerated, while the electrical input is extracted by processing a part of the optical input signal. The signal at the output of the proposed regenerator based relay has lower intensity fluctuations compared to a conventional optical amplifier based relay. We have tested our proposed regenerator-based relay under medium and strong turbulence conditions by choosing the refractive index structure parameters as $5\times 10^{-15}\,\,m^{-2/3}$ and $5\times 10^{-10}\,\,m^{-2/3}$ , respectively. Our simulation results show that the proposed regenerator-based relay reduces the received power penalty by $3.5~dB$ compared to the conventional amplifier-based relay, under strong turbulence conditions.

A cost efficient and reliable single mode fiber and free space optics based hybrid 32 × 5 Gbps ultra dense wavelength division multiplexed-passive optical network architecture employing optical comb and polarization multiplexing is proposed. The proposed architecture is a step forward towards shifting the next generation wireless network traffic over existing passive optical network to achieve the optimum bandwidth, capacity, quality of service and cost efficiency for mobile subscribers. Self-restorable passive optical networks having fiber based feeder and distribution paths are widely researched in various studies in the past. However, to the best of our knowledge, a self-restorable passive optical network architecture employing free space optics based protection path has not been proposed so-far. The effect of varying polarization mode dispersion from 0.02 to 0.06 ps . km - 0.5 and the refractive index structure parameter of the Gamma-Gamma channel model from 5 × 10 - 16 to 5 × 10 - 12 m - 2 / 3 is evaluated. A techno-economic performance analysis of the architecture for downstream is performed by considering both the distribution and protection paths. It has been shown that the receiver sensitivity for a polarization mode dispersion of 0.06 ps . km - 0.5 is around - 22 dBm and for strong turbulence is around - 20 dBm .

According to World Health Organization, 5—18% births around the world are premature, and this rate is on its rise. Recent trend has been to develop computational tools which could support obstetricians in their daily practice. This work is aimed at extracting novel diagnostic features for term vs. preterm births classification based on the dynamics of contraction and non-contractions (dummy) intervals. To achieve this, 26 uterine records of 18 pregnant women, resulting in 13 term and 13 preterm deliveries, were analyzed in this study. Each record was of 30-min duration, and comprised three electrohysterographic (EHG) and one externally recorded tocographic (Toco) signal. Granger causal analysis of contraction and dummy intervals of recorded signals was performed to extract potential features. These include coupling strength and directionality indices, and were subsequently utilized by a quadratic discriminator to classify between term and preterm births. The extracted features achieved high discriminatory power of 94%, 95%, 91%, and 97% for sensitivity, specificity, classification accuracy, and area under the ROC curve, respectively. These findings show that Granger causal analysis might be adopted as a computational tool to quantify EHG-Toco dynamics for the risk-assessment of the preterm delivery.

Glaucoma is an eye disease that can cause loss of vision by damaging the optic nerve. It is the world's second leading cause of blindness after cataracts. Early diagnosis of glaucoma is a key to prevent permanent blindness as it has no noticeable symptoms in its early stages. Color fundus photography is used for examining the optic disc (OD) which is an important step in the diagnoses of glaucoma. This is done by estimating the cup-to-disc ratio (CDR). In this paper, we proposed a Cup Disc Encoder Decoder Network (CDED-Net) for the joint segmentation of optic disc (OD) and optic cup (OC). We have eradicated the pre-processing and post-processing steps to reduce the computational cost of the overall system. Segmentation of (OD) and OC is modeled as a semantic pixel-wise labeling problem. The model was trained on the DRISHTI-GS, RIM-ONE and REFUGE datasets. Experiments show that our CDED-Net system achieves state-of-the-art OD and OC segmentation results on these datasets.

In this letter, we investigate the optimization of uplink (UL) channel state information (CSI) training in the full-duplex (FD) based multiuser (MU) multiple-input multiple-output (MIMO) systems. Here, an FD-assisted BS performs simultaneous UL CSI training and downlink data transmission that produces self interference (SI). Following the UL training stage, the BS uses the conventional half-duplex (HD) MU MIMO transmission with zero-forcing precoding. To find an optimal UL CSI training length that achieves a balance between the training overhead and CSI quality, we formulate an optimization problem that maximizes the sum spectral efficiency of the network. To ease the analysis, we derive a lower bound on the user rate in the FD phase, which is then used together with the HD user rate to obtain the sub-optimal solution. We also provide a closed-form expression to approximate the UL training length. Numerical results show that the performance of the proposed UL training outperforms the fixed length training and it closely matches the performance with an exhaustive search.

Efficient data dissemination is a key challenge for IoT applications. In this paper, we present an ergodic achievable rate analysis of the non-orthogonal multiple access (NOMA)-based cooperative transmission scheme in spectrum-sharing cognitive radio networks (CRNs). The transmission scheme consists of two phases, where the NOMA transmission strategy is employed at the secondary transmitter (ST) in the second phase to serve the primary receiver (PR) and secondary receivers (SRs). This cooperative spectrum-sharing transmission is favourable when the ST-PR link is strong and the ST faces a spectrum scarcity issue. To evaluate the performance of the network over Nakagami-m channels, ergodic achievable rates at PR and SRs are derived in closed forms, which can be used for any integer or non-integer value of fading index m. Finally, we compare the results of the analytical expressions with simulated results for validation.

This paper investigates relay selection policies in a full-duplex (FD) based underlay cooperative cognitive radio network. We consider a scenario consisting of multiple pairs of primary users (PUs) with access to the spectrum, and the multiple pairs of secondary users (SUs) with no dedicated spectrum access. Each pair (PU or SU) comprises of a unique set of transmitter and receiver. The secondary transmitter (ST) supports the FD transmission with the simultaneous transmission of the information to its own receiver and reception of the designated PU signal for relaying. First, we formulate an optimization problem to maximize the PU rate by optimizing the transmission power at the relay (i.e., ST), keeping the SU rate fixed. Second, we propose two low-complexity relay selection schemes based on the sum rate maximization, namely, centralized successive and distributed prioritized matching schemes. Numerical results show that the proposed schemes perform close to the exhaustive selection schemes.

We demonstrate all-optical generation of width-tunable mono-cycle pulses for ultra-wideband communication. It has been shown that the width of the mono-cycle pulses can be tuned dynamically by simply varying the power of the optical signal. We also investigate the regenerative property of the nonlinear medium-based technique for the generation of mono-cycle pulses. For the purpose of comparison, ultra-wideband mono-cycle pulses are also generated through the optical delay line-based technique. It has been demonstrated through numerical simulations that the nonlinear medium-based technique is highly resilient to amplified spontaneous emission noise that is induced over the optical signal. Furthermore, we have shown that the highly nonlinear fiber-based nonlinear medium performs better than the semiconductor optical amplifier-based medium. Bit error rate measurements are taken for different values of optical signal-to-noise ratios in order to elaborate our work.

In this paper, we propose a full duplex architecture based on a hybrid link composed of free space optics (FSO) and multimode plastic optical fiber (MMPOF) for short-range wireless access networks. The proposed architecture employs mode group division multiplexing (MGDM) and wavelength reuse techniques to transmit data between central unit (CU) and radio access units (RAUs). An optical frequency comb source to generate multiple optical sidebands is realized using a single laser source to provide 60 GHz millimeter-wave (mm-wave) signals at each RAU by simultaneously transmitting PAM-4 signal on linearly polarized (LP) modes of each optical sideband. Data rate of 2$$\times$$ × 12 Gbps at mm-wave frequency of 60 GHz is achieved for both downlink (DL) and uplink (UL) transmissions. The transmission of 2$$\times$$ × 12 Gbps PAM-4 signal over hybrid FSO-MMPOF link is investigated at different values of refractive index structure parameter ($$C_n^2$$ C n 2 ) by employing log-normal (LN) FSO channel model to support three RAUs in a ring topology. The acceptable receiver sensitivities below −5 and −0.6 dBm for DL and UL transmissions are achieved, respectively. The proposed hybrid architecture can be a potential candidate for future communication networks.

We demonstrate a high data rate and low-cost OM4 multimode fiber (MMF) and free-space optics (FSO)-based self-restorable 2 × 100 Gbps per wavelength intra data center interconnect between two pairs of servers. This transmission system is based on two vertical cavity surface-emitting lasers that are directly modulated with PAM-4 data at the rate of 100 Gbps and multiplexed using mode division multiplexing of two linearly polarized modes. In case a fault occurs in the MMF-based primary path, the traffic is shifted to FSO-based protection path through a specially designed triggering and switching mechanism. Offline digital signal processing is used at the receiver to process the received PAM-4 signal for compensating the effects of channel impairments. The performance of the proposed architecture is evaluated at link lengths of 35 and 70 m under normal and faulty scenarios. The effect of varying the refractive index structure parameter of the log-normal channel model and the effect of mode coupling between linearly polarized (LP) modes on the bit-error-rate performance is also analyzed under different conditions. We observe that the performance of the FSO-based protection path is better than the OM4-based primary path at a forward error correction limit of 3.8 × 10 − 3 bit-error-rate.

Nodes in a body area network (BAN) are miniature wearable or implantable battery-powered wireless sensors which continuously transmit real time vital physiological data of a patient to remote health-care center while remaining in close proximity to the human body. Therefore, BAN nodes should have the features of high data rates and low transmit powers in order to protect the human body, environment and bio-medical equipment from harmful exposure of electromagnetic radiations and electromagnetic interference (EMI). Ultra-wideband (UWB) signals have low allowable transmission power and high data rates. Therefore, we propose a low cost, low powered and secure optical body area network (OBAN) composed of four UWB-BAN nodes each transmitting at a data rate of 30 Mbps. At the control node, UWB signals from UWB-BAN nodes are encoded using spectral amplitude coding-optical code division multiple access (SAC-OCDMA) scheme and the combined signal is transmitted over free space optics (FSO) channel towards remote health-care center. At the health-care center, the combined signal is decoded and UWB signal of each UWB-BAN node is photodetected for analysis of patient's data. Log-Normal channel model is considered between control node and the health-care center. The signal received from each UWB-BAN after propagation through the FSO channel is analyzed through Bit error rate (BER) results. It was observed that the proposed architecture requires the UWB-BAN nodes to have low receiver sensitivities with the added benefits of cost-efficiency and data security.

In this paper, we address the performance optimization of Holmium doped fiber amplifier (HDFA) for optical communications in 2–2.15 μm wavelength range based on a single in-band forward pump source. The performance of the HDFA is analyzed with the help of theoretical simulations by considering an optimized length of Holmium doped fiber (HDF), doping concentration of Ho3+, and pump power. The impact of signal wavelength and power on gain, amplified spontaneous emission (ASE) noise, and noise figure (NF) of the amplifier is investigated. Furthermore, we investigate the variations in the gain of the amplifier, its output power, and NF by varying the power and wavelength of the pump source. After optimizing the parameters of the amplifier, the peak gain observed is around 56.5 dB, the 3 dB saturated output power obtained is 33.3 dBm, and the output power is 3 W at signal wavelength of 2.0321 μm for HDF having an optimized length of 12 m and pump power of 3.5 W. Minimum NF of around 8.2 dB is observed at 2.0321 μm for signal power of −5 dBm. The impact of ion-ion interaction on the performance of HDFA is also investigated. A reduction of 24.2 dB and 0.051 W is observed in peak gain and output power of HDFA, respectively by considering the ion-ion interaction.

In this paper, we propose and demonstrate through numerical simulations a novel, to the best of our knowledge, widely tunable and switchable multiwavelength erbium-doped fiber laser (EDFL) operating in the 1524–1650 nm wavelength range covering the C-, L-, and U-bands. The EDFL is based on a single ring cavity and a single forward pump source operating at 980 nm wavelength. The length of the erbium-doped fiber and pumping configuration is optimized, enabling a wide tuning of 126 nm with an average lasing power of 15 dBm. Switchable multiple wavelengths are generated from the EDFL through an intracavity tunable optical filter (TOF) and a specially designed out-of-cavity comb filter (CF). Forty-nine wavelengths having average optical power and linewidth of around −10 dBm and 0.01 nm, respectively, are obtained at the output of the CF. Moreover, the free spectral range among the multiple wavelengths is adjusted easily by simply varying the frequency of sinusoidal radio frequency signal used to modulate the lasing signal obtained by tuning the intracavity TOF at a particular wavelength with the help of a dual-drive Mach–Zehnder modulator. The proposed EDFL is low cost, efficient, and highly stable with an average output power of around 15 dBm for 10% output coupling ratio over a 126 nm wide tuning range covering C-, L- and U-bands.

This paper undertakes the ancillary topic of relation between the transmission capacity of two dimensional optical code division multiple (2D-OCDMA) systems and its economic aspects. A new code called 2D double weight zero cross-correlation (2D-DZCC) is developed and implemented in both spectral-spatial and spectral-temporal 2D-OCDMA systems for a comprehensive techno-economic analysis. In order to determine the most efficient network architecture in terms of system capacity and cost, both models are evaluated for allowed bandwidth in terms of data, and reach. The technological analysis is followed by investigation of capital expenditure (CAPEX) for both architectures in terms of the cost incurred on network components between the transmitter and receiver modules. Evaluation of both models demonstrates that spectral-temporal OCDMA system tends to provide relatively same transmission capacity with $$\approx 70 \%$$ reduced cost of implementation in comparison with the spectral-spatial system. Consequently, making spectral-spatial systems most suitable for the deployment of passive optical network (PON) at the low cost access domain.

With many applications in high level scene understanding, salient object detection is an important objective. In addition, this topic has received significant attention recently. This work proposes techniques that exploit the role of color spaces for addressing two important challenges in relation to salient object detection. The autonomous identification of a color space by which to carry out the processing has always been of prime importance to most image analysis tasks and this is equally so in relation to saliency detection. To address this challenge, a new adaptive color space selection method is proposed, here, which autonomously identifies the color space that is locally the most appropriate for saliency detection on an image by image basis. The color channels within this identified local color space are aggregated using joint l2, 1-norm minimization in order to determine feature importance and also to achieve feature selection leaning. A process relevant to saliency detection is multi-modality feature fusion, in which multiple features and color spaces are used in combination to capture the saliency aspects of an image/region. To implement this second process, a new technique for the region based optimal combination of feature modalities is introduced. The results of the rigorous experimental evaluations demonstrate the effectiveness of the adaptive color space selection and also for the region based optimal combination methods in comparison to 13 other state-of-the-art saliency methods and all in relation to three benchmark datasets. The efficacy of the proposed color space selection and region based combination methods is further validated by examining their ability to select appropriate color spaces for, and successfully aggregate the results of, up to five benchmark methods.

The baroreflex being a key modulator of cardiovascular control ensures adequate blood pressure regulation under orthostatic stress which otherwise may cause severe hypotension. Contrary to conventional baroreflex sensitivity indices derived across a-priori traditional frequency bands, the present study is aimed at proposing new indices for the assessment of baroreflex drive which follows active (supine to stand-up) and passive (supine to head-up tilt) postural changes. To achieve this, a novel system identification approach of principal dynamic modes (PDM) was utilized to extract data-adaptive frequency components of closed-loop interactions between beat-to-beat interval and systolic blood pressure recorded from 10 healthy humans. We observed that the gain of low-pass global PDM of cardiac arm (:feedback reflex loop, mediated by pressure sensors to adjust heart rate in response to arterial blood pressure), and 0.2 Hz global PDM of mechanical arm (:feed-forward pathways, originating changes in arterial blood pressure in response to heart rate variations) may function as potential markers to distinguish active and passive orthostatic tests in healthy subjects.

Musculoskeletal tuberculosis constitutes 3 percent of extra pulmonary secondary tuberculosis predominantly involving the spine. The variations in its presentation and unclear symptoms make diagnosis difficult in early period. The normal lab values like ESR, TLC, DLC and no clear history of previous pulmonary infection makes the picture unclear and delays the diagnosis. Present work is the overview of the presentation of various musculoskeletal presentations, efficacy of BCG vaccination, time delay in diagnosis, laboratory parameters, x rays and other radiological changes etc. The reliability of the various lab procedures like AFB stain, histopathology, tuberculosis bacteria culture and cartridge-based nucleic acid amplification test (CBNAAT) has also been overviewed.