Dual-wavelength transmission system using double micro-resonator system for EMI healthcare applications

Microsystem Technologies - To meet the 5G requirements for higher bandwidth, the focus has been shifted to millimeter waves paving the way to radio over fiber (RoF) in order to minimize radio...     

RFID Transponder Collision Control Algorithm

Transponder collision problem can be significant when a large number of RFID (radio frequency identification) transponders exist in field. Most existing anti-collision algorithms can solve this problem. However, problem arises when all or part of these transponders are having identical UID (unique identification). This paper proposes a new transponder collision control algorithm to overcome overlapping that occurs among transponders with identical UID in RFID large scale deployment (e.g., in a large warehouse), so that the RFID reader can successfully identify the quantity of transponders for each particular UID with high identification accuracy. The proposed anti-collision algorithm adopts a modified version of frequency domain method by adding stochastic delays in time domain. The obtained results show that the proposed method can achieve optimum frequency bandwidth utilization and at the same time poses high identification accuracy (almost 100%) with low identification delay.     

Power-domain non orthogonal multiple access (PD-NOMA) in cooperative networks: an overview

Wireless Networks - Non-orthogonal multiple access (NOMA) scheme is emerging as a favourable multiple access scheme for future 5G networks. Compared to orthogonal multiple access techniques, NOMA...     

Performance of All-Optical Multicasting Via Dual-Stage XGM in SOA for Grid Networking

The letter presents a study on the performance of an all-optical multicasting technique utilizing the nonlinearity of semiconductor optical amplifier (SOA) technology for all-optical grid computing network. The technique not only has the capability to optically control the degree of multicasting but also performs all-optical switching simultaneously. Experimental results show the design's capability to multicast an incoming 10-Gb/s optical signal onto 16 outgoing signals using cross-gain modulation in a single SOA. A second SOA is also included in the design as a 2R regenerator     

Utilization Model for HCCA EDCA Mixed Mode in IEEE 802.11e

This letter proposes an analytical model to characterize medium utilization in IEEE 802.11e operating in HCCA‐EDCA mixed mode (HEMM). In contrast to existing works which model the backoff process in individual stations, we consider the channel occupancy pattern. Additionally, our work considers the operation of HEMM, which is not widely documented. We show that the proposed model accurately characterizes medium utilization with no more than 5% error.     

DABPR: a large-scale internet of things-based data aggregation back pressure routing for disaster management

In this paper, we propose a data aggregation back pressure routing (DABPR) scheme, which aims to simultaneously aggregate overlapping routes for efficient data transmission and prolong the lifetime of the network. The DABPR routing algorithm is structured into five phases in which event data is sent from the event areas to the sink nodes. These include cluster-head selection, maximization of event detection reliability, data aggregation, scheduling, and route selection with multi attributes decision making metrics phases. The scheme performs data aggregation on redundant data at relay nodes in order to decrease both the size and rate of message exchanges to minimize communication overhead and energy consumption. The proposed scheme is assessed in terms of packet delivery, network lifetime, ratio, energy consumption, and throughput, and compared with two other well-known protocols, namely “information-fusion-based role assignment (InFRA)” and “data routing for in-network aggregation (DRINA)”, which intrinsically are cluster and tree-based routing schemes designed to improve data aggregation efficiency by maximizing the overlapping routes. Meticulous analysis of the simulated data showed that DABPR achieved overall superior proficiency and more reliable performance in all the evaluated performance metrics, above the others. The proposed DABPR routing scheme outperformed its counterparts in the average energy consumption metric by 64.78% and 51.41%, packet delivery ratio by 28.76% and 16.89% and network lifetime by 42.72% and 20.76% compared with InFRA and DRINA, respectively.

     

Training size optimization with reduced complexity in cell-free massive MIMO system

Training sequence is used in multiple antenna systems to estimate channel state information and mitigate channel distortion between transmitter and receiver. However, the training sequence or pilot must be limited to a certain size in order to reduce the impact of overhead loss due to limited channel coherence length in mobile users. In this paper, we proposed to use training size optimization in cell-free massive MIMO system. In addition, we proposed and compared the performance of different training size optimization algorithms, namely exhaustive search optimization, bisection optimization and min–max optimization, with each method has different level of calculation complexities. The results showed that in general, all of the 3 training length optimization methods improved the downlink rate compared to the conventional pilot length method. We also showed that the training optimization methods are more effective when the coherence length is small or the number of users is very large. In the case of large number of users or small coherence length, the exhaustive search has the best median downlink rate, followed closely by min–max optimum and finally the bisection method. Even though the exhaustive search optimization has the best downlink rate, we showed that the proposed reduce optimization complexity methods has significantly less calculation complexity. In addition, the median downlink rate performance of min–max optimization method is only slightly less than that of the exhaustive search method for various number of users and coherence length.

     

Analytical and experimental studies on asymmetric bundle fiber displacement sensors

A fiber-optic displacement sensor (FODS) is theoretically and experimentally studied using an asymmetrical bundled fiber. The bundled fiber consists of two parallel fibers with different core radial ratios (CRRs) to achieve different sensitivity and dynamic range for displacement measurements. Both analytical modeling and experimental observations show that the linear range and sensitivity can be adjusted by controlling the CRR between transmitting and receiving fibers. This increases the flexibility of the sensor, which can be used for precise non-contact sensing applications.     

First-order PMD compensation using optical FIR filter

We present a synthesis algorithm to design an optical finite impulse response (FIR) filter for compensating a first-order polarization mode dispersion (PMD) by minimizing the differential group delay (DGD). The desired frequency response was approximated using two widely used methods in designing digital FIR filters: the Fourier series expansion method and the frequency sampling method. A numerical simulation was performed for an eighth-order filter to demonstrate the difference between the two methods. The simulation results produced a sharper cutoff for the Fourier series expansion and higher stopband attenuation for the frequency sampling method. The Fourier series method produced better results in reducing the DGD.