Split Architecture Research Articles

5G Wireless Transport in a PON Context: An Overview

The high capacity of future 5G wireless networks must be supported by equivalent high-capacity fixed networks for backhaul and fronthaul (x-haul) transport. Especially the trend toward densification of radio networks, in which many small cells are located next to macrocells, will call for cost-efficient x-haul solutions to meet the overall business case targets. Optical access technologies bear great potential to offer low-cost solutions for these x-haul transport links. Starting from requirements on bandwidth, latency, and other critical parameters of 5G x-haul transport networks, ITU-T Q2/SG15 has elaborated a generic approach on how to employ PON technologies in various functional split architectures of wireless networks. The proposed PON architectures are presented and discussed in the recently released supplementary document G.Sup66, "5G Wireless Fronthaul Requirements in a PON Context," in October 2018. This article provides a high-level summary of the findings in Supplement G.Sup66.

Low electronegativity Mn bulk doping intensifies charge storage of Ni2P redox shuttle for membrane-free water electrolysis

A high efficiency electrochemical energy storage and high areal capacitance solid-state mediator can act as an energy vector to solve the key problem in mixtures of H2 and O2 in electrically driven water splitting architectures.

Energy Management of Low-Pressure Systems Utilizing Pump-Unloading Valve and Accumulator

In the context of improving energy efficiency and fuel consumption of mobile hydraulic equipment, it is important to analyze all the sources of power loss occurring within the hydraulic systems. While plenty of analyses have been performed on the working implements and the main transmission systems, very little attention has been paid to low-pressure (LP) systems until recently. LP systems are required on closed-circuit hydraulic systems to replenish losses, provide cooling flow, and maintain a pilot pressure necessary to operate hydraulic control valves and variable displacement units. It is shown that these circuits, which are often thought to have minimal impact on power consumption, actually cause significant, continuous power loss. A new method of power savings in these circuits is investigated through management of charge pump flow by application of an accumulator-sense pump-unloading (ASPU) valve. This work further proposes the combination of a split LP architecture with an ASPU valve. Three systems are simulated using Simcenter Amesim® and MATLAB/Simulink®. Using realistic duty cycles and unit loss models on a circuit for mobile off-road hydraulic equipment, it is shown that a standard LP system can consume about 5 kW of power. Power savings of up to 65% over a standard LP system are demonstrated by the proposed architecture.

Performance analysis of dual connectivity in control/user-plane split heterogeneous networks

To ensure seamless mobility, logical separation between control plane and data plane has been evolved as a promising solution for the forthcoming fifth generation (5G) cellular networks. Here, macro-cells provide control coverage using a low frequency band signal, whereas small-cells provide high data rates to the mobile terminals (MTs) over high frequency band signals. While performing frequent handovers over small-cells, throughput perceived by an MT may fall below the requested data rate. To deal with the high data rate demand of the forthcoming 5G networks, recently dual connectivity (DC) technology has been proposed for long term evolution (LTE) networks in Release 12. However, analyzing the performance of DC in control/user-plane (C/U) split LTE heterogeneous networks is quite limited in the preceding literature. In this work, we propose an analytical framework to compare the performances of DC with hard handover in C/U split architecture in terms of system throughput and saturation probability, i.e., the probability that the total demand for resources exceeds the total capacity of the serving cells. Our proposed framework explicitly considers the data rate demands of the MTs, traffic arrival pattern and channel conditions. The analytical results have also been validated against simulation results. Our analyses reveal that the performance gain of DC over traditional hard handover is actually conditional on underlying traffic load density and call arrival rates.

Analysis and Design of a Large Dither Injection Circuit for Improving Linearity in Pipelined ADCs

In this paper, a new large dither injection technique is proposed for improving linearity in pipelined analog-to-digital converters (ADCs), without losing the dynamic range of the ADCs and deteriorating the corresponding amplifier’s linearity. First, analyses of a proper pipelined ADC’s architecture are performed for large dither injection. Then, a 9-bit capacitive digital-to-analog converter (DAC) with split architecture is developed to inject the dither ranging from −511/1024 least significant bit (LSB) to 511/1024 LSB of the first stage. To counteract the consumption of the correction range by the capacitive injection dither, the novel 6-bit complementary DACs embedded in the comparator threshold generation circuit are proposed to realize comparator dither injection. In addition, the dither injection amplitude is configurable for investigating different amplitude’s effects on the linearity of the ADC. Finally, the proposed dither injection circuit, together with a 16-bit 150 million samples per second (MSPS) ADC, is implemented in a 0.18- $\mu \text{m}$ CMOS technology. The measured results demonstrate the effectiveness of the proposed techniques. The optimum dither is the 9-bit dither, improving not only the spurious free dynamic range (SFDR) of the small signal by at least 13 dB but also that of the large signal by more than 8 dB compared to the case without dither injection. Moreover, dither injection makes the noise floor clean.

An Efficient Algorithm for mmWave MIMO Systems

Efficient and Symmetry based precoding plays a key role in wireless communications. In order to improve the transmission performance of multi-user millimeter wave Multiple-Input Multiple-Output (MIMO) (MU-mmWave MIMO) systems, this paper proposes an analog precoding scheme for the receiver of mmWave MIMO with split sub-array hybrid analog and digital architecture. Then, we propose a hybrid analog and digital precoding algorithm based on channel reciprocity (APoCR) to maximize the spectral efficiency by utilizing the triple joint optimization problem, which can be divided into the analog and digital part. The analog combination vectors (ACVs) are obtained by the signal-to-interference-and-noise ratio (SINR) reception maximization of each downlink user and the analog precoding vectors (APVs) are obtained by the SINR reception maximization of each uplink antenna array. The digital precoder of the transmitter is designed after the analog part optimization to alleviate the interference between multiple data streams of the users. The simulation results show that the proposed precoding algorithm has a better sum rate, fast convergence, and improved SINR than the other state-of-the-art algorithms.

Optimization issues for data rate in energy harvesting relay-enabled cognitive sensor networks

This paper looks into an energy harvesting (EH) relay-enabled cognitive radio wireless sensor network (CR-WSN) considering power splitting (PS) architecture. More specifically, a relay (RU) harvesting energy from the signals transmitted from a secondary user transmitter (ST,) and using the harvested energy to forward the resulting signals to another sensor node subsequently is being investigated. This scheme can be broken down into two components, i.e., a sensor node physically placed near the transmitter (SPNT) and a sensor node physically placed far from the transmitter (SPFT). The closed-form expressions for the successful transmission probability (STP) and the achievable data rate in both cases can be derived analytically. In order to quantify the energy consumption, the system energy efficiency (EE) is examined. Furthermore, the achievable data rate was optimized in three possible scenarios, i.e., the trade-off between the sum data rate and the sum harvested energy (R-E), the achievable data rate at RU, and the joint optimization of the power allocation and PS ratio in case of SPNT. A Monte Carlo simulation has been performed to verify the theoretical analysis obtained, and to show the impact of different parameters on system performance.

A Split-Based Digital Background Calibration of Pipelined Analog-to-Digital Converters by Cubic Spline Interpolation Filtering

In this paper, a digital background calibration technique for pipelined analog-to-digital converter (ADC) based on the concept of split architecture is proposed to address finite dc gain and nonlinearity of the residue amplifier. In the proposed method, the pipelined ADC divided into two channels where each channel included the first stage followed by an ideal backend ADC. A 1.5 bit per stage is chosen for the first stage of each channel where a pseudorandom sequence is injected before one of the channels. The difference between the digital outputs of two channels is used to drive an interpolation filter to correct the mentioned errors. Since splines modeled high nonlinearity with weakly nonlinear functions, it selected for interpolation filtering which results in low computational overhead and fast convergence time. Behavioral simulations of a 12-bit 100 MS/s pipelined ADC show that the convergence time of the algorithm is approximately 4 × 104 clock cycles and the signal-to-noise and distortion ratio and the spurious free dynamic range improved from 32 dB/35 dB to 70 dB/75 dB.

A 78.5-dB SNDR Radiation- and Metastability-Tolerant Two-Step Split SAR ADC Operating Up to 75 MS/s With 24.9-mW Power Consumption in 65-nm CMOS

This paper presents a 14-bit radiation- and metastability-tolerant two-step split successive-approximation register (SAR) analog-to-digital converter (ADC) that achieves a 78.5-dB peak signal-to-noise-and-distortion ratio (SNDR) and a 103-dB peak spurious-free dynamic range (SFDR) at 35 MS/s. The prototype operates up to 75 MS/s with less than 25-mW power consumption. To tolerate errors originating from radiations and/or metastability, multiple redundancy techniques are implemented hierarchically from the system level to the circuit level. At the system level, the deployment of the split architecture plus a few additional error detection techniques not only identify but also correct the errors, leading to a p to p <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> error rate reduction. These detection techniques include a residue over- and under (OU)-flow detection using the second-stage digital codes, an extra bit (EB)-cycle error detection with LSB repeating using a larger digital-to-analog converter (DAC) capacitor, and a parity bit (PB) error detection for on-the-fly SAR data latch protection. Sub-radix-2 DAC and reference voltage scaling also create circuit-level intra- and inter-stage redundancy, further improving the robustness of the conversion process. Preamplifier sharing and offset digital calibration alleviate the offset problem between the residue amplifier (RA) and the first-stage comparator. Two reference buffers are implemented on chip with a 1.8-V supply. Fabricated in a 65-nm CMOS process, the ADC core occupies an active area of 0.342 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Transceiver Design for Downlink SWIPT NOMA Systems With Cooperative Full-Duplex Relaying

This paper studies the application of simultaneous wireless information and power transfer (SWIPT) to downlink non-orthogonal multiple access (NOMA) system. A novel cooperative NOMA protocol for high communication reliability and user fairness is proposed, where a near NOMA user acts as a full-duplex (FD) energy-harvesting relay to help transmission from the source node S to the far NOMA user. The power splitting (PS) architecture is adopted at the relay to perform the SWIPT. The aim is to maximize the data rate of the near NOMA user while satisfying the QoS requirement of the far NOMA user and the energy causality condition of the near NOMA user. The formulated problem is a non-convex fractional programming. By jointly optimizing the power allocation factor, the PS ratio, the receiver filter, and the transmit beamforming, we propose alternative optimization (AO)-based algorithm to obtain an optimal solution. In addition, a low-complexity suboptimal scheme is proposed and the semi-closed form solution is derived to characterize the performance of our proposed design. The simulation results verify the correctness of theoretical analysis and show performance gain of our proposed protocol over the existing transmission protocols.

Robust Beamforming Design in a NOMA Cognitive Radio Network Relying on SWIPT

This paper studies a multiple-input single-output non-orthogonal multiple access cognitive radio network relying on simultaneous wireless information and power transfer. A realistic non-linear energy harvesting model is applied and a power splitting architecture is adopted at each secondary user (SU). Since it is difficult to obtain perfect channel state information (CSI) in practice, instead either a bounded or Gaussian CSI error model is considered. Our robust beamforming and power splitting ratio are jointly designed for two problems with different objectives, namely, that of minimizing the transmission power of the cognitive base station and that of maximizing the total harvested energy of the SUs, respectively. The optimization problems are challenging to solve, mainly because of the non-linear structure of the energy harvesting and CSI errors models. We converted them into convex forms by using semi-definite relaxation. For the minimum transmission power problem, we obtain the rank-2 solution under the bounded CSI error model, while for the maximum energy harvesting problem, a two-loop procedure using a 1-D search is proposed. Our simulation results show that the proposed scheme significantly outperforms its traditional orthogonal multiple access counterpart. Furthermore, the performance using the Gaussian CSI error model is generally better than that using the bounded CSI error model.

Energy Efficiency Maximization Design for Full-Duplex Cooperative NOMA Systems With SWIPT

This paper investigates non-orthogonal multiple access (NOMA) system, where the near NOMA user is able to communicate with a base station (BS) directly while the far NOMA user needs to resort to a full-duplex (FD) relay. Wireless power transfer is applied to our system where the FD relay integrated with power splitting architecture can be powered wirelessly by the ambient radio signals simultaneously. Moreover, we assume that self-interference cancellation at the relay and inter-user interference cancellation at the near NOMA user are imperfect. For the purpose of maximizing the energy efficiency of the NOMA system, the power splitting ratio and transmit beamforming vectors are researched for the BS and relay with the guarantee of QoS requirements for two users. The formulated problem appears to be nonlinear fractional programming, which is highly nonconvex and the global optimality is hard to obtain. By introducing Charnes-Cooper's transformation and inner approximation method, we develop an iterative algorithm to gain the near optimal solution. The simulation results show that the proposed joint optimizing algorithm outperforms the existing scheme in terms of energy efficiency as well as the effect of SI cancellation on performance gain.

Designing security of personal data in distributed health care platform

The object of research is the design of EHR system capable for both patient-physician communication and secure and privacy preserving cross-organisational analytical collaboration. Constant patient monitoring and amount of quality data available for further analysis is crucial for more accurate medical recommendations and therefore general wellbeing. On the other hand, most of the current architectural approaches are subject to different vulnerabilities to data integrity and can’t provide multi-party computations (MPC) proof from sensitive information leakage resulting in very fragmented datasets available for each clinic or health organisation. Another improvement area is edge level sensor network communication security.In this paper it is proposed to split architecture into layers with dedicated security zones. This fragmentation allows to effectively segment infrastructure, allowing each element to apply to its own authentication and authorization requirements as well as secure data individually. Side effect of this approach is reducing network load and eliminating security and privacy issues by minimising sensitive data transfer (e. g. basic data gathering and processing is being performed on the smart sensors). Usage of Hyperledger is suggested for maintaining data integrity with off-chain database for optimizing transactions storage and speed. Utilization of MPC allows to share records between akin organisations for joint calculations and ml-models training without revealing actual data.Suggested approaches allow building robust and flexible yet secure platform for sensitive data gathering, analysis and multi-party processing without revealing users’ identities leveraging advantages of edge computing, Hyperledger and joint data calculations.

Energy efficiency optimization for SWIPT in K-user MIMO interference channels

In this paper, we investigate the energy efficiency (EE) for K-user multiple-input multiple-output (MIMO) interference channels with simultaneous wireless information and power transfer (SWIPT) and interference alignment (IA). Specifically, power splitting architecture is leveraged at each receiver for information decoding (ID) and energy harvesting simultaneously. Taking the quality of service (Qos) requirement and harvested power constraints into consideration, we maximize the system EE by jointly designing transmit beamformers, transmit power, power splitters and receive filters. To solve the nonconvex EE optimization problem, we first eliminate the interference among users for ID via the maximal signal to interference plus noise ratio (Max-SINR) IA method, which yields a two-dimensional EE optimization problem. And then, we propose an EE-Max algorithm coupled with the Max-SINR, nonlinear fraction programming and one dimension searching to solve the reformulated problem. Simulation results show the effectiveness of the proposed EE optimization algorithm and reveal the influence of the maximum transmit power constraint and the QoS requirement on the system EE.

The Performance Analysis of Multi-Layer Split-Protocol

The growing need for high-performance networking is achieved with parallel processing; several networking functions are processed concurrently in order to accomplish a performance Networking Architecture. Open systems interconnection (OSI) model is an example of multi-layering structure, and each layer performs definite function unique to that layer. OSI model works on pass it on principle, and it is divided in two stacks lower stack and upper stack. Layers 4 - 7 represent upper stack and responsible for data applications. The remaining 1 - 3 layers represent the lower stack and mostly involve in data movement. There are many techniques are available for server optimization enhancing the availability by distributing the load among peer servers. According to our knowledge, nobody has implemented such splitting architecture across the entire OSI model. In this paper, we present multilayer Split-protocol (MLSP) a high performance, reliable and secure technique for spiting an application or network protocol across OSI model, and we present the design, implementation, and empirical performance evaluation of MLSP. It is the ideal choice for Cloud services where each functional component is considered an independent of each other.

Discrete Power Control and Transmission Duration Allocation for Self-Backhauling Dense mmWave Cellular Networks

Wireless self-backhauling is a promising solution for dense millimeter wave (mmWave) small cell networks, the system efficiency of which, however, depends upon the balance of resources between the backhaul link and access links of each small cell. In this paper, we address the discrete power control and non-unified transmission duration allocation problem for self-backhauling mmWave cellular networks, in which each small cell is allowed to adopt individual transmission duration allocation ratio according to its own channel and load conditions. We first formulate the considered problem as a non-cooperative game ${\mathcal {G}}$ with a common utility function. We prove the feasibility and existence of the pure strategy Nash equilibrium (NE) of game $ {\mathcal {G}}$ under some mild conditions. Then, we design a centralized resource allocation algorithm based on the best response dynamic and a decentralized resource allocation algorithm (DRA) based on control-plane/user-plane split architecture and log-linear learning to obtain a feasible pure strategy NE of game ${\mathcal {G}}$ . For speeding up convergence and reducing signaling overheads, we reformulate the considered problem as a non-cooperative game ${{\mathcal {G}}'}$ with local interaction, in which only local information exchange is required. Based on DRA, we design a concurrent DRA to obtain the best feasible pure strategy NE of game ${\mathcal {G}'}$ . Furthermore, we extend the proposed algorithms to the discrete power control and unified transmission duration allocation optimization problem. Extensive simulations are conducted with different system configurations to demonstrate the convergence and effectiveness of the proposed algorithms.

A Split Architecture Approach to Terabyte-Scale Caching in a Protocol-Oblivious Forwarding Switch

Research has proven that in-network caching is an effective way of eliminating redundant network traffic. For a larger cache that scales up to terabytes, a network element must utilize block storage devices. Nevertheless, accessing block devices in packet forwarding paths could be a major performance bottleneck because storage devices are prone to be much slower than memory devices concerning bandwidth and latency. Software-defined networking (SDN) has entered into all aspects of network architecture by separating the control and forwarding plane to make it more programmable and application-aware. Protocol-oblivious forwarding (POF), which is an enhancement to current OpenFlow-based SDN forwarding architecture, enhances the network programmability further. In this paper, we proposed a novel split architecture to cope with the problem of speed mismatch between high-speed packet forwarding and low-speed block I/O operation over POF switches. The issues raised by this split architecture were first explored and could be summarized as packet dependency and protocol conversion. Then, we focused on solving these two problems and proposed an efficient and scalable design. Finally, we conducted extensive experiments to evaluate the split architecture along with the proposed approaches for packet dependency and protocol conversion.

A Statistical Design Approach Using Fixed and Variable Width Transconductors for Positive-Feedback Gain-Enhancement OTAs

The positive-feedback gain-enhancement operational transconductance amplifier (OTA) design is a promising architecture to scale into deep submicron CMOS. Ever smaller CMOS process nodes require analog circuit designs that can overcome the area–power-matching relation. We introduce a Nauta OTA with a split architecture consisting of fixed width and digitally programmable variable width transconductors utilizing the minimum grid-spacing of the CMOS process enabling an active mismatch cancelation technique. A variation-aware statistical design practice is introduced to analyze the sizing of transconductors, computing code-word solutions for statistically likely solutions, and estimating average maximum dc gain over the entire code-space of many simulated OTAs. Prototypes of a 8-bit differential OTA in 180-nm CMOS designed using the Nauta structure fixed width and digitally programmable variable width architecture achieves an average maximum dc gain of 60 dB, simulated unity gain frequency of 4.6 GHz, and a figure-of-merit of 1 GHz/mW.

Co-channel Interference Energy Harvesting for Decode-and-Forward Relaying

In this paper, co-channel interferences are exploited for energy harvesting in a Cooperative Network (CICN) in which a power constrained relay uses a power splitting architecture (CICN-PS) and a time switching architecture (CICN-TS) to harvest energy from the radio-frequency signals received from a source node and co-channel interferences. In the proposed CICN-PS and CICN-TS protocols, the relay applies decode-and-forward technology to decode the information of the source node, and then forwards the recoded information to a destination with the overall harvested energies. The system performance of the proposed protocols is discussed and evaluated using the exact throughput analyses and is then checked using Monte Carlo simulations over Rayleigh fading channels. The optimal power splitting ratio and energy harvesting time are derived by the Golden Section Search method, and throughput performance evaluations are performed. Our numerical and simulation results show distributions as follows. Firstly, the CICN-PS protocol outperforms the CICN-TS protocol. Secondly, the proposed protocols strictly depend on the location, amount and power of the co-channel interferences. Thirdly, when signal-to-noise ratio increases, the proposed CICN-PS protocol achieves the perfect throughputs where the cooperative relay applies the ideal receiver and co-channel interferences do not affect the destination. Finally, the numerical analyses agree well with the simulation results.

Secrecy outage of SWIPT in the presence of cooperating eavesdroppers

This work investigates the secrecy performance of a simultaneous wireless information and power transfer system that operates in the presence of cooperating eavesdroppers. The multi-antenna access point’s transmission is used for information-decoding by a multi-antenna node and for energy-harvesting (EH) by multiple single-antenna nodes. However, some of the nodes authorized for EH only attempt to eavesdrop on the ongoing information transmission by utilizing a generalized on–off power splitting architecture. We derive a closed-form expression for the secrecy outage probability of the considered Multiple-Input-Multiple-Output Multiple-Eavesdroppers system. Theoretical and simulation results are provided to validate the derived results.