BER Analysis of Reconfigurable Intelligent Surface Assisted Downlink Power Domain NOMA

The use of software controlled passive Reconfigurable Intelligent Surface (RIS) in wireless communications has attracted many researchers in recent years. RIS has a certain degree of control over the scattering and reflection characteristics of the electromagnetic waves, compared to the conventional communications in which the received signal is degraded due to the uncontrollable scattering of the transmitted signal and its interaction with the objects in propagating medium. Further, in RIS assisted communications, the phases of the multiple incoming signals can be controlled to enable constructive addition of multiple signals from different channel paths to improve Signal to Noise Ratio (SNR). On the other hand, Non-Orthogonal Multiple Access (NOMA) provides massive connectivity and low latency. The power domain variant NOMA uses superposition coded symbols with different powers for different user symbols. In this paper, a novel RIS assisted downlink NOMA system is proposed by combining the merits of both RIS and NOMA to improve the reliability of the system. Analytical expressions are derived for the Bit Error Rate (BER) performance of the proposed RIS assisted power domain NOMA system. The BER performance of the proposed system is analyzed using the numerical simulation results. It is observed that the proposed system has better performance than the conventional NOMA system.Comment: 4 pages, 5 figures, accepted manuscript for a conference, peer reviewe

Experience with Generic Pegylated L-asparaginase in Children with Acute Lymphoblastic Leukemia from a Tertiary Care Oncology Center in South India

Abstract Dhaarani Jayaraman Background Acute lymphoblastic leukemia (ALL) is a common type of leukemia in children. The innovator pegylated L-asparaginase has several advantages over native L-asparaginase; however, its use in India is limited due to availability and cost. Therefore, a generic pegylated L-asparaginase can be considered as an alternative to the innovator molecule. Methods A retrospective study was conducted to assess the outcome (minimal residual disease [MRD]) and toxicity of a generic pegylated L-asparaginase (Hamsyl) at the end of induction therapy. Results Eighty-eight (80.7%) and 21 (19.3%) patients had received generic pegylated L-asparaginase and conventional asparaginase, respectively, as a part of their treatment protocol. Nearly 82% of patients had B-type ALL. Eight-one percent of children had a white blood cell count of fewer than 50,000/mm3. At the end of induction, 80.7% (88) of children were minimal residual disease (MRD)-negative, and at the end of augmented consolidation therapy, 20.2% were MRD-negative. Ten percent of patients exhibited allergic reactions. Two children had pancreatitis, and one child had central venous thrombosis. Conclusion The generic pegylated L-asparaginase (Hamsyl) was effective and safe for use in pediatric ALL

Performance Analysis of Full Duplex Bidirectional Machine Type Communication System Using IRS with Discrete Phase Shifter

In this paper, passive Intelligent Reflecting Surface (IRS) is used to enhance the performance of a Full Duplex (FD) bidirectional Machine Type Communication (MTC) system with two source nodes. Each node is equipped with two antennas to operate in FD mode. In reality, self-interference and discrete phase shifting are two major impairments in FD and IRS-assisted communication, respectively. The self-interference at source nodes operating in FD mode is mitigated by increasing the number of meta-surface elements at the IRS. Bit Error Rate (BER) and outage performances are analyzed with continuous phase shifting and discrete phase shifting in IRS. Closed-form analytical expressions are derived for the outage probability and BER performances of the IRS-assisted bidirectional FD-MTC system with a continuous phase shifter. The outage and BER performances of the IRS-assisted bidirectional MTC system in the FD mode have Signal-to-Noise Ratio (SNR) improvement compared with the IRS-assisted bidirectional MTC system in Half Duplex (HD) mode, as the number of reflecting elements in IRS is doubled in the FD mode. The outage and BER performances are degraded by a discrete phase shifter. Hence, performance degradation of the proposed IRS-assisted bidirectional FD-MTC is examined for 1-bit shifter (0, π), 2-bit shifter (0, π/2, π, 3π/2), and for 3-bit shifter (0, π/4, π/2, 3π/4, π, 5π/4, 3π/2, 7π/4). The performance degradation when a discrete phase shifter is employed in IRS is compared with the ideal continuous phase shifter in IRS. Further, achievable rate analysis is carried out for finding the best location of the IRS in a bidirectional FD-MTC system

Outage Probability Analysis and Transmit Power Optimization for Blind-Reconfigurable Intelligent Surface-Assisted Non-Orthogonal Multiple Access Uplink

Fifth-generation (5G) advancements improve transmitter and receiver functionalities, but the propagation environment remains uncontrolled. By changing the phase of impinging waves, reconfigurable intelligent surfaces (RIS) have the potential to regulate radio propagation environments. RIS-assisted non-orthogonal multiple access (NOMA) improves spectrum efficiency while enabling massive connectivity. The uplink outage probability expressions for blind-RIS-NOMA are derived in this work using RIS as a smart reflector (SR) and RIS as an access point (AP). Extensive Monte-Carlo simulations are performed to validate the derived closed-form expressions. The optimal powers to be allocated to the users are also derived in order to maximize the uplink sum capacity. In comparison to the sub-optimal power allocation, the optimal power allocation enhances the sum capacity. In terms of sum capacity for 20 dB signal-to-noise ratio (SNR) and 32 reflecting elements, it is demonstrated that the blind-RIS-NOMA surpasses the conventional NOMA by ≈38%. The sum capacity and outage performances are enhanced by the addition of RIS elements