Multi-set space-time shift keying and space-frequency space-time shift keying for millimeter-wave communications

In this paper, we introduce a novel OFDM-aided multifunctional multiple-input multiple-output scheme based on multi-set space-time shift keying (MS-STSK), where the information transmitted over each subcarrier is divided into two parts: STSK codeword and the implicit antenna combination (AC) index. In MS-STSK, a unique combination of antennas can be activated at each subcarrier to convey extra information over the AC index while additionally transmitting the STSK codeword. Furthermore, inspired by the MS-STSK concept, this scheme is extended also to the frequency domain in the novel context of our multi-space-frequency STSK (MSF-STSK), where the total number of subcarriers is partitioned into blocks to implicitly carry the block's frequency index. The proposed MSF-STSK scheme benefits from the huge bandwidths available at mmWaves for partitioning the total number of OFDM subcarriers into blocks to convey more information over the frequency domain. Both proposed systems use STSK codewords as the basic transmission block, and they can achieve higher data throughput and better BER performance than STSK. Moreover, given that the system is meant to operate at mmWaves, antenna arrays relying on several antenna elements are employed at both the transmitter and receiver for analogue beamforming with the aid of phase shifters and power amplifiers to overcome the effect of high path loss

Multi-user steered multi-set space-time shift-keying for millimeter-wave communications

The recently proposed concept of multiset space-time shift keying (MS-STSK) is intrinsically amalgamated with the multiple-input multiple-output (MIMO) philosophy for the sake of enhancing the attainable system throughput. Explicitly, we propose a multiuser steered MS-STSK (MU-SMS-STSK) scheme for the downlink of millimeter-wave (mmWave) communications, which is combined with analogue beamforming (BF) that relies on phase shifters and power amplifiers to overcome the high attenuation of mmWaves. Hence, our MU-SMS-STSK system combines the concepts of MU-MIMO, MS-STSK, BF, and orthogonal frequency-division multiplexing for communicating with multiple users relying on the same time and frequency resources

Layered multi-group steered space-time shift-keying for millimeter-wave communications

We propose a novel multi-user Multiple-Input Multiple-Output (MIMO) technique termed as the Layered Multi-Group Steered Space-Time Shift Keying (LMG-SSTSK) for the downlink of millimeter wave (mmWave) communications, which combines the concepts of Multi-User MIMO (MU-MIMO), Space-Time Shift Keying (STSK), beamforming and Orthogonal Frequency-Division Multiplexing (OFDM) to simultaneously convey information to multiple users. The LMG-SSTSK tackles the propagation challenges of the high-attenuation mmWave frequencies by sub-dividing the users into multiple groups. The proposed system allows more users to be served simultaneously in the downlink over the same time-and frequency-resources than a system dispensing with the proposed grouping technique

Low-Complexity Expectation Propagation Detection for Uplink MIMO-SCMA Systems

We consider uplink sparse code multiple access (SCMA) systems associated with multiple input multiple output (MIMO), where the transmitters and the receiver are equipped with multiple antennas, for enhanced reliability (diversity gain) or improved data rate (multiplexing gain). For each diversity or multiplexing based MIMO scheme combined with SCMA, we develop low-complexity iterative detection algorithms based on the message passing algorithm (MPA) and the expectation propagation algorithm (EPA). We show that the MIMO-SCMA under EPA enjoys the salient advantage of linear complexity (in comparison to the MPA counterpart with exponential complexity) as well as enhanced error rate performances due to the MIMO transmission. We also show that the performance of EPA depends on the codebook size and the number of antennas

Multi-set space-time shift-keying with reduced detection complexity

In this treatise, we propose a novel Multi-Set Space-Time Shift Keying (MS-STSK) technique, where the source bits are conveyed over two components, namely by activating one out of MQ dispersion matrices of Space-Time Shift Keying (STSK) and M Antenna Combination (AC) of the Nt available antennas, in a similar fashion to Spatial Modulation (SM) but activating multiple antennas rather than a single antenna. This system requires a smaller number of RF chains than Antenna Elements (AEs) to achieve an improved throughput. We opt for STSK as the main building block of our proposed MS-STSK as a benefit of its design flexibility, where STSK is capable of providing the system with both diversity and multiplexing gains. The proposed MS-STSK system achieves both higher data rates and a lower Bit Error Rate (BER) than the conventional STSK scheme, which is attained at the cost of increased number of antenna elements and a high-speed antenna switch. Furthermore, as the symbol rate of the MS-STSK system increases, its performance compared to the STSK scheme is significantly improved, because of the enhanced diversity introduced by the additional antenna elements. Furthermore, we propose a reduced complexity detector for QAM/PSK constellations, which - despite its reduced complexity - is capable of achieving the same performance as the optimal Maximum Likelihood (ML) detector

The impact of accreditation of primary healthcare centers: successes, challenges and policy implications as perceived by healthcare providers and directors in Lebanon

BACKGROUND: In 2009, the Lebanese Ministry of Public Health (MOPH) launched the Primary Healthcare (PHC) accreditation program to improve quality across the continuum of care. The MOPH, with the support of Accreditation Canada, conducted the accreditation survey in 25 PHC centers in 2012. This paper aims to gain a better understanding of the impact of accreditation on quality of care as perceived by PHC staff members and directors; how accreditation affected staff and patient satisfaction; key enablers, challenges and strategies to improve implementation of accreditation in PHC. METHODS: The study was conducted in 25 PHC centers using a cross-sectional mixed methods approach; all staff members were surveyed using a self-administered questionnaire whereas semi-structured interviews were conducted with directors. RESULTS: The scales measuring Management and Leadership had the highest mean score followed by Accreditation Impact, Human Resource Utilization, and Customer Satisfaction. Regression analysis showed that Strategic Quality Planning, Customer Satisfaction and Staff Involvement were associated with a perception of higher Quality Results. Directors emphasized the benefits of accreditation with regards to documentation, reinforcement of quality standards, strengthened relationships between PHC centers and multiple stakeholders and improved staff and patient satisfaction. Challenges encountered included limited financial resources, poor infrastructure, and staff shortages. CONCLUSIONS: To better respond to population health needs, accreditation is an important first step towards improving the quality of PHC delivery arrangement system. While there is a need to expand the implementation of accreditation to cover all PHC centers in Lebanon, considerations should be given to strengthening their financial arrangements as well

MIMO Evolution Beyond 5G Through Reconfigurable Intelligent Surfaces and Fluid Antenna Systems

With massive deployment, multiple-input-multiple-output (MIMO) systems continue to take mobile communications to new heights, but the ever-increasing demands mean that there is a need to look beyond MIMO and pursue the next disruptive wireless technologies. Reconfigurable intelligent surface (RIS) is widely considered a key candidate technology block to provide the next generational leap. The first part of this article provides an updated overview of the conventional reflection-based RIS technology, which complements the existing literature to include active and semiactive RIS, and the synergies with cell-free massive MIMO (CF mMIMO). Then, we widen the scope to discuss the surface-wave-assisted RIS that represents a different design dimension in utilizing metasurface technologies. This goes beyond being a passive reflector and can use the surface as an intelligent propagation medium for superb radio propagation efficiency. The third part of this article turns the attention to the fluid antenna, a novel antenna technology that enables a diverse form of reconfigurability that can combine with RIS for ultrahigh capacity, power efficiency, and scalability. This article concludes with a discussion of the potential synergies that can be exploited between MIMO, RIS, and fluid antennas

Predictors and outcomes of patient safety culture in hospitals

<p>Abstract</p> <p>Background</p> <p>Developing a patient safety culture was one of the recommendations made by the Institute of Medicine to assist hospitals in improving patient safety. In recent years, a multitude of evidence, mostly originating from developed countries, has been published on patient safety culture. One of the first efforts to assess the culture of safety in the Eastern Mediterranean Region was by El-Jardali et al. (2010) in Lebanon. The study entitled "The Current State of Patient Safety Culture: a study at baseline" assessed the culture of safety in Lebanese hospitals. Based on study findings, the objective of this paper is to explore the association between patient safety culture predictors and outcomes, taking into consideration respondent and hospital characteristics. In addition, it will examine the correlation between patient safety culture composites.</p> <p>Methods</p> <p>Sixty-eight hospitals and 6,807 respondents participated in the study. The study which adopted a cross sectional research design utilized an Arabic-translated version of the Hospital Survey on Patient Safety Culture (HSOPSC). The HSOPSC measures 12 patient safety composites. Two of the composites, in addition to a patient safety grade and the number of events reported, represented the four outcome variables. Bivariate and mixed model regression analyses were used to examine the association between the patient safety culture predictors and outcomes.</p> <p>Results</p> <p>Significant correlations were observed among all patient safety culture composites but with differences in the strength of the correlation. Generalized Estimating Equations for the patient safety composite scores and respondent and hospital characteristics against the patient safety grade and the number of events reported revealed significant correlations. Significant correlations were also observed by linear mixed models of the same variables against the frequency of events reported and the overall perception of safety.</p> <p>Conclusion</p> <p>Event reporting, communication, patient safety leadership and management, staffing, and accreditation were identified as major patient safety culture predictors. Investing in practices that tackle these issues and prioritizing patient safety is essential in Lebanese hospitals in order to improve patient safety. In addition, further research is needed to understand the association between patient safety culture and clinical outcomes.</p

Therapeutic potential of active components of saffron in post-surgical adhesion band formation

Background Abdominal adhesions are common and often develop after abdominal surgery. There are currently no useful targeted pharmacotherapies for adhesive disease. Saffron and its active constituents, Crocin and Crocetin, are wildly used in traditional medicine for alleviating the severity of inflammatory or malignant disease. Purpose The aim of this study was to investigate the therapeutic potential of the pharmacological active component of saffron in attenuating the formation of post-operative adhesion bands using different administration methods in a murine model. Material method saffron extract (100 mg/kg), Crocin (100 mg/kg), and Crocetin (100 mg/kg) were administered intraperitoneally and by gavage in various groups of male Wistar rat post-surgery. Also three groups were first treated intra-peritoneally by saffron extract, Crocin, and Crocetin (100 mg/kg) for 10 days and then had surgery. At the end of the experiments, animals sacrificed for biological assessment. Result A hydro-alcoholic extract of saffron and crocin but not crocetin potently reduced the adhesion band frequency in treatment and pre-treatment groups in the mice given intra-peritoneal (i.p) injections. Following the saffron or crocin administration, histological evaluation and quantitative analysis represented less inflammatory cell infiltration and less collagen composition, compared to control group. Moreover, the oxidative stress was significantly reduced in treatment groups. Conclusion These findings suggest that a hydro-alcoholic extract of saffron or its active compound, crocin, is a potentially novel therapeutic strategy for the prevention of adhesions formation and might be used as beneficial anti-inflammatory or anti-fibrosis agents in clinical trials. Taxonomy Abdominal surgeries/post-surgical adhesions

Transceiver design for millimetre-wave communications: a space-time-frequency multi-functional processing approach

In this thesis, we investigate a suite of transceiver designs for transmission over millimetre wave (mmWave) channels. Furthermore, we conceive the philosophy of Layered Multi-Group (LMG) arrangements relying on the concept of Multi-Functional Multiple- Input Multi-Output (MF-MIMO) systems. More specifically, we propose an amalgam of various MIMO techniques, namely diversity, multiplexing and beamforming techniques as well as Multi-User MIMO (MU-MIMO), user grouping and antenna layering methods, which are capable of simultaneously gleaning various MIMO advantages for the sake of overcoming the unfavourable propagation characteristics of mmWave signals. The mm- Wave channel suffers both from high path loss and sparse scattering, which results in reduced receiver diversity.To mitigate these problems, we propose the LMG Steered Space-Time Shift Keying (LMG-SSTSK) system. More specifically, the LMG-SSTSK system is capable of achieving an enhanced multiplexing gain and an improved diversity gain by relying on STSK, and a beamforming gain with the aid of analogue beamforming. Additionally, LMG-SSTSK is capable of supporting multi-user communication using MU Transmit Precoding (MUTPC) as well as an increased number of served users with the aid of sophisticated antenna layering and user grouping. We opt for STSK as the main transmission scheme, since it is an MF-MIMO, which is capable striking a design trade-off between the achievable throughput and the attainable diversity gain. Additionally, the system employs Orthogonal Frequency-Division Multiplexing (OFDM) for transmitting over the mmWave wideband channel, which imposes frequency selective fading due to its high bandwidth, where time dispersion is imposed by the delay of the sparse multipath components. The above-mentioned antenna grouping and user grouping concepts were introduced into the LMG-SSTSK system in order to overcome the restrictions imposed by the mmWave channel in MU scenarios, where due to the high path loss and the beamforming employed, the system cannot simultaneously support angularly dispersed users. Hence, the users are partitioned into groups and the proposed MF-MIMO communicates with all users by conceiving antenna layering.On the other hand, in order to enhance the LMG-SSTSK’s achievable throughput, we propose the novel Multi-Set Space-Time Shift Keying (MS-STSK) scheme. The MSSTSK system constitutes an improved version of STSK and has the potential of outperforming other MIMO arrangements by appropriately choosing the MS-STSK’s parameters. In MS-STSK, a single dispersion matrix is activated using a classical PSK/QAM symbol and transmitted by activating a single Antenna Combination (AC), where an AC is defined as a unique set of multiple antenna elements out of those available at the transmitter. The achievable throughput of MS-STSK depends on the AC allocation technique employed. Hence, the Distinct Antenna Allocation (DAC) technique and the Shared Antenna Allocation (SAC) technique are conceived. The DAC technique requires a distinct set of antenna elements in each antenna combination, while the antenna elements are shared among the available ACs with the aid of SAC, hence MS-STSK associated with DAC achieves an enhanced performance at the cost of a reduced throughput compared to its SAC counterpart, which strikes a design trade-off between them. Furthermore, in order to transmit over the mmWave channel, we intrinsically amalgamate both OFDM and analogue beamforming with MS-STSK using our OFDM-aided MS-STSK system, leading to our OFDM-MS-STSK system. We further exploit the frequency dimension for enhancing the achievable throughput of the OFMD-aided MS-STSK system by introducing the Multi-Space-Frequency STSK (MSF-STSK) system. Accordingly, we introduce our MU Steered MS-STSK (MU-SMS-STSK) system by employing MU-TPC in OFDMMS- STSK for simultaneously supporting multiple users. Finally, to mitigate the angular selectivity of the beamforming-aided mmWave channel, we reintroduce the LMG structure in the LMG-SMS-STSK arrangement. Additionally, in order to achieve near-capacity performance using the classical MSSTSK scheme, we conceive a serially-concatenated channel coding assisted MS-STSK scheme. More specifically, we devise a soft-decision-aided MS-STSK decoder associated with an iterative two-stage serially-concatenated inner detector and outer decoder, which is designed by relying on EXtrinsic Information Transfer (EXIT) charts. Finally, in order to transmit over the mmWave channel, our soft-decision-aided scheme is combined with wideband techniques, such as OFDM and Single-Carrier Frequency Division Equalisation (SC-FDE), as well as beamforming, where due to the DFT and IDFT mismatch introduced by OFDM, we opt for SC-FDE to retain the advantage of MS-STSK having to rely on a reduced number of RF-chains