Propagation Loss Measurement of Wireless Body Area Network at 2.4 GHz and 3.35 GHz Bands

The main purpose of this work is to measure and analyze the propagation loss of the Wireless Body Area Network (WBAN) in frequency and time domain at two frequency bands, namely 2.4 GHz band with 80 MHz bandwidth and 3.35 GHz band with 500 MHz bandwidth. Four different scenarios (front to front, front to back, front to off-body node and back to off-body node) using many antenna´s locations on the body are used to investigate the channel response (path loss) of WBAN. It is found that the front to front channels and the front to off-body node channels have a low fading. The front to back channels and the back to off-body node channels have a high fading that can be approximated by the Distorted Rayleigh fading. Thus the WBAN range for the front to off-body node scenario is more than the range of the back to off-body node scenario.

     

1.8 V–3 GHz CMOS limiting amplifier with efficient frequency compensation

A compact robust CMOS limiting amplifier (LA) for high data traffic optical links is presented in this work. The core considers two different blocks. First, four common-source inverter amplifiers are included, which optimize the gain-bandwidth product of the structure. And second, two additional compensation stages are placed strategically between the gain stages alleviating the pernicious load effect. These stages develop two different compensation techniques simultaneously thus increasing the bandwidth. The proposed design consumes 113 mW with a single 1.8 V supply. It achieves a cut-off frequency up to 3 GHz and provides a gain of 21 dB. The circuit is packaged in a QFN24 and mounted on a commercial FR4 PCB.     

Performance Analysis of Path Loss Models at 1.8 GHz in an Indoor/Outdoor Environment to Verify Network Capacity and Coverage

Wireless Personal Communications - Cloud is an environment where the resources are outsourced as service to the cloud consumers based on their demand. The cloud providers follows pay as you go...     

Human Body Shadowing at 28 GHz

Wireless Personal Communications - It is well known that human body shadowing is a significant propagation effect in indoor communications especially at frequencies higher than 10 GHz....     

LTE网络覆盖规划技术研究

为了保障高质量的网络部署,LTE系统的覆盖规划对网络的建设成本及质量发挥着至关重要的作用。文章基于LTE实际组网的规划需求,结合系统化的理论及仿真分析,对LTE无线接入的链路及网络特征进行了深入的研究。在此基础上,开发形成一套完整的LTE蜂窝网络覆盖规划理论及应用方法,为LTE无线网络规划提供了基础性的技术指导。     

Research on LTE Network Coverage Planning

When deploying an LTE network,coverage planning is critical to reduce construction costs and ensure network quality.This paper considers actual network planning requirements and combines theory with simulation analysis to study LTE wireless access link and network characteristics.A theory for LTE cellular coverage planning and application methods is proposed that lays the basic foundation for LTE cellular networks.     

Current source load for HBT low-noise-amplifier linearisation at 1.8 GHz

A novel method employing a current source load lineariser is introduced to enhance the nonlinear performance of an HBT low-noise amplifier. This load compensates for the nonlinear behaviour of the amplifying transistor; obtaining a highly linear amplifier, achieving an IIP3 close to 20 dB and showing an independent test tone spacing behaviour.     

SBT (Sense Before Transmit) Based LTE Licenced Assisted Access for 5 GHz Unlicensed Spectrum

Utilization of unlicensed spectrum under licensed assisted access ensuring fair co-existence with Wi-Fi networks is a good solution to address immense usage of mobile data. Radio communication operation of LTE in unlicensed frequency band is referred as LTE-unlicensed (LTE-U) or LTE-licensed assisted access. In this paper, we consider a HGNW in which coverage area of Wireless-Fidelity (Wi-Fi)’s Access Point is integrated within the LTE-U small base station’s cellular network coverage area. To overcome the disadvantages of existing LTE-U technics like carrier sense adaptive transmission and listen before talk, we proposed a new methodology i.e., sense before transmit in this paper by adopting a transmit power control mechanisms using reciprocity theorem based on the channel state information to assign the secondary carriers in the uplink as well as in the downlink directions in the unlicensed spectrum to carry the traffic. In our proposal, LTE-U users are allowed to use the unlicensed spectrum provided that the interference produced at Wi-Fi users due to LTE-U activities is remained below a certain threshold. We evaluated the performance of proposed network model in terms of outage probability and achievable throughputs.

     

Analysis and design of a 1.8-2.7 GHz tunable 8-band TDD LTE receiver front-end

This paper describes the analysis and design of a 0.13μm CMOS tunable receiver front-end that supports 8 TDD LTE bands,covering the 1.8-2.7 GHz frequency band and supporting the 5/10/15/20 MHz bandwidth and QPSK/16QAM/64QAM modulation schemes.The novel zero-IF receiver core consists of a tunable narrowband variable gain low-noise amplifier(LNA),a current commutating passive down-conversion mixer with a 2nd order low pass trans-impedance amplifier,an LO divider,a rough gain step variable gain pre-amplifier,a tunable 4th order Chebyshev channel select active-RC low pass filter with cutoff frequency calibration circuit and a fine gain step variable gain amplifier.The LNA can be tuned by reconfiguring the output parallel LC tank to the responding frequency band,eliminating the fixed center frequency multiple LNA array for a multi-mode receiver. The large various gain range and bandwidth of the analog baseband can also be tuned by digital configuration to satisfy the specification requirement of various bandwidth and modulation schemes.The test chip is implemented in an SMIC 0.13μm 1P8M CMOS process.The full receiver achieves 4.6 dB NF,-14.5 dBm out of band IIP3, 30-94 dB gain range and consumes 54 mA with a 1.2 V power supply.     

LTE/Wi-Fi Coexistence in 5 GHz ISM Spectrum: Issues,Solutions and Perspectives

Wireless Personal Communications - The introduction of a high number of small cells in cellular networks and the complementary adoption of WLAN technologies in unlicensed spectrum are interesting...     

TD-LTE无线网络规划研究

本文主要从覆盖规划上简述了TD-LTE系统的规划特点,并比较了TD-LTE系统与TD-SCDMA系统的异同,并就TD-LTE的无线链路预算进行了讨论。     

无人机飞行过程中信号弱区的分析

无人机在实际飞行过程中，在某些区域总会出现通信误码率较高甚至失锁的现象。通过分析无人机链路的信道特点，利用两径传播模型分析了信号电平衰落的分布和深衰落担度，并用MATLAB对此模型进行了仿真。仿真数据与工程经验数据进行了比较，结果表明此模型能够很好的解释飞行弱区这种现象，也进一步验证了该模型的适用性。     

Optimization of a Novel Rectenna for RF Energy Harvesting at 2.45 GHz

In this work, the different elements of a rectenna were optimized for the energy harvesting from Wi-Fi at 2.45 GHz, using the particle swarm optimization method with real or hybrid dimensions depending on the element. The antenna was optimized in different steps and for each one the effect on its performance was determined. For the rectifier, several commercial diodes were compared for evaluating the best selection for this application. Additionally, a low pass filter and an impedance matching of L-section were implemented as coupling elements. The antenna from the novel rectenna had a gain equal to 4.42 dBi due to the incorporation of a pixeled metasurface structure in the ground layer, and a maximum conversion efficiency of 73% with the diode SMS-7630. In this sense, the optimized rectenna presented a better performance than others from the literature for RF energy harvesting at 2.45 GHz. Therefore, the proposed rectenna can be a good alternative as a power supply in nodes of wireless sensor networks with the addition of the DC–DC boost converter LTC3105.

     

部署LTE对3G网络规划的挑战

随着物联网和移动宽带时代的到来,移动数据业务呈现爆炸式增长,现有的移动网承载技术将很难满足未来数据业务需求,移动业务市场需求和竞争是LTE技术产生与发展的源动力。本文分析了LTE演进的必然性及目前的发展情况;并从频段使用、承载网、核心网等方面讨论了在引入LTE时,网络规划应重点处理好的问题。     

射线跟踪模型在LTE无线网络规划中的应用

随着LTE的部署与发展,传统的无线传播模型已无法满足LTE实际规划的需要。文章首先分析了射线跟踪模型在LTE无线仿真的准确性,并在实际网络规划中加以应用。测试结果证明,基于射线跟踪模型的仿真对LTE试验网基站布局的影响及其指导意义。     

Tailoring of Electromagnetic Absorption in Substituted Hexaferrites from 8.2 GHz to 12.4 GHz

Journal of Electronic Materials - Microwave absorbers are an important topic of interest to mitigate electromagnetic interference. Here, we have investigated electromagnetic absorption properties...     

1.8 GHz class E power amplifier for wireless communications

The authors present a 1.8 GHz class E power amplifier for wireless communications. A fully integrated class E power amplifier module was designed, fabricated and tested. The circuit was implemented in a self-aligned-gate, depletion mode 0.8 μm GaAs MESFET process. The amplifier delivers 23 dBm of power to the 50Ω load, with a power added efficiency of 57% at a supply voltage of 2.4 V