Ultra‐wideband Coexistence with WiBro

Interference effects of ultra‐wideband devices using the frequency band from 3.1 to 10.6 GHz on wireless broadband are evaluated. The ultra‐wideband emission power spectral density that would be necessary to protect a wireless broadband station is considered. Also, an analytic scheme based on a system level simulation of a WiBro system is proposed.     

10‐Gbit/s Wireless Communication System at 300 GHz

A 10‐Gbit/s wireless communication system operating at a carrier frequency of 300 GHz is presented. The modulation scheme is amplitude shift keying in incoherent mode with a high intermediate frequency (IF) of 30 GHz and a bandwidth of 20 GHz for transmitting a 10‐Gbit/s baseband (BB) data signal. A single sideband transmission is implemented using a waveguide‐tapered 270‐GHz highpass filter with a lower sideband rejection of around 60 dB. This paper presents an all‐electronic design of a terahertz communication system, including the major modules of the BB and IF band as well as the RF modules. The wireless link shows that, aided by a clock and data recovery circuit, it can receive 2⁷?1 pseudorandom binary sequence data without error at up to 10 Gbit/s for over 1.2 m using collimating lenses, where the transmitted power is 10 μW.     

A New Automatic Compensation Network for System‐on‐Chip Transceivers

This paper proposes a new automatic compensation network (ACN) for a system‐on‐chip (SoC) transceiver. We built a 5 GHz low noise amplifier (LNA) with an on‐chip ACN using 0.18 µm SiGe technology. This network is extremely useful for today's radio frequency (RF) integrated circuit devices in a complete RF transceiver environment. The network comprises an RF design‐for‐testability (DFT) circuit, capacitor mirror banks, and a digital signal processor. The RF DFT circuit consists of a test amplifier and RF peak detectors. The RF DFT circuit helps the network to provide DC output voltages, which makes the compensation network automatic. The proposed technique utilizes output DC voltage measurements and these measured values are translated into the LNA specifications such as input impedance, gain, and noise figure using the developed mathematical equations. The ACN automatically adjusts the performance of the 5 GHz LNA with the processor in the SoC transceiver when the LNA goes out of the normal range of operation. The ACN compensates abnormal operation due to unusual thermal variation or unusual process variation. The ACN is simple, inexpensive and suitable for a complete RF transceiver environment.     

Co‐simulation‐based modeling and performance analysis of hybrid fiber–wireless links

We present a new approach for the performance analysis of hybrid fiber/wireless communication systems. This approach is based on a co‐simulation using two types of dedicated software: the first is used for RF/wireless systems whereas the second is devoted to optical communication systems. The proposed method enables simultaneous simulation of all elements of the radio‐over‐fiber link with accurate modeling. A low‐cost wireless local area network over a fiber distribution system is implemented in order to validate the results experimentally. Simulation results are in good agreement with experimental measurements in terms of EVM evolution for different link element configurations. Copyright © 2011 John Wiley & Sons, Ltd.     

基于GP2010的移动GPS射频前端设计

对GPS射频前端进行了研究与设计,实现了GPS信号射频到数字中频的转化过程。应用GP2010芯片设计出了符合要求的GPS射频前端,包括前端滤波器、低噪声放大器,以及中频滤波器。介绍测试系统的搭建,对实际制作的电路板进行调试,并得出测试结果,为后期基于FPGA实现GPS基带数字信号处理提供GPS数字中频信号,为自主设计GPS接收机奠定了基础。     

Binary Power Amplifier with 2‐Bit Sigma‐Delta Modulation Method for EER Transmitter

A novel power amplifier for a polar transmitter is proposed to achieve better spectral performance for a wideband envelope signal. In the proposed scheme, 2‐bit sigma‐delta (ΣΔ) modulation of the envelope signal is introduced, and the power amplifier configuration is modified in a binary form to accommodate the 2‐bit digitized envelope signals. The 2‐bit ΣΔ modulator lowers the noise of the envelope signal by fine quantization and thus enhances the spectral property of the RF signal. The Ptolemy simulation results of the proposed structure show that the spectral noise is reduced by 10 dB in a full transmit band of the EDGE system. The dynamic range is also enhanced. Since the performance is improved without increasing the over‐sampling ratio, this technique is best suited for wireless communication with high data rates.     

RF Band‐Pass Sampling Frontend for Multiband Access CR/SDR Receiver

Radio frequency (RF) subsampling can be used by radio receivers to directly down‐convert and digitize RF signals. A goal of a cognitive radio/software defined ratio (CR/SDR) receiver design is to place the analog‐to‐digital converter (ADC) as near the antenna as possible. Based on this, a band‐pass sampling (BPS) frontend for CR/SDR is proposed and verified. We present a receiver architecture based second‐order BPS and signal processing techniques for a digital RF frontend. This paper is focused on the benefits of the second‐order BPS architecture in spectrum sensing over a wide frequency band range and in multiband receiving without modification of the RF hardware. Methods to manipulate the spectra are described, and reconstruction filter designs are provided. On the basis of this concept, second‐order BPS frontends for CR/SDR systems are designed and verified using a hardware platform.     

Integrated load‐based power saving for real‐time and nonreal‐time traffic in LTE‐TDD

Long‐Term Evolution (LTE) is a 4G wireless broadband technology developed by the Third Generation Partnership Project. Two duplex modes, namely, frequency division duplex and time division duplex (TDD), are defined in LTE for transmission in both downlink and uplink directions simultaneously. Power saving mechanisms for LTE‐frequency division duplex were proposed in the authors' previous work. Applicability of the previously proposed mechanisms to LTE‐TDD is investigated in this paper, and the idea of “virtual time” associated with the mapping mechanism from the virtual time domain to the actual time domain for different TDD configurations is proposed. With the help of the mapping mechanism, 3 revised power saving schemes are proposed to support real‐time user equipments and nonreal‐time user equipments in LTE‐TDD. Simulation study demonstrates the effectiveness of the mapping mechanism as well as the benefit of the proposed schemes in power saving efficiency and real‐time support in comparing with the standard‐based mechanism.     

An anti‐repeater‐jamming approach based on blind source separation for the downlink of satellite communication systems

In this paper, an anti‐jamming approach is proposed for the downlink of satellite communication systems when encountering a hostile repeater‐jamming. Based on blind source separation, this approach can eliminate repeater‐jamming by separating the mixtures of the communication signals and the repeater‐jamming. Meanwhile, oversampling method is employed to transform the underdetermined mixing of signals into a determined mixing for facilitating the separation. In the simulations, the symbol error ratio (SER) of the separated communication signals can approximate the theory SER, and the anti‐repeater‐jamming capacity can arrive to nearly 28 dB.     

一种低功耗数字式人工关节无线监视系统

提出了一种由压电陶瓷和射频电路供电的低功耗数字式人工关节无线监视系统。该系统监视人工关节的工作情况,通过传感器得到人工关节的异常压力、磨损情况等数据,经过数模转换、存储后,通过射频信号,以无线方式发送至体外电路。对系统的各个部分进行了详细描述。部分电路已经得到流片验证或仿真,测试结果符合系统要求。     

Performance analysis of smart antenna test-bed operating in awide-band CDMA channel

In this paper, we present a performance analysis of a smart antenna system operating in a wide-band CDMA wireless-local-loop channel using a beam-forming module (BFM) that has been implemented on a digital signal processor (TMS320C6701) board. We first show the results of computer simulations obtained from the modeled received (RX) signals through a test-bed system consisting solely of baseband signal processing parts, i.e., modeled RX data-generating PC, BFM for computing the optimal weight vector and interfacing module. A test-bed system of the entire base station is then implemented to evaluate the adaptive beam-forming function with the actual wireless signals. This test-bed system includes several subscribers, as well as the array antenna, RF modules, and other receiving parts required at the cell site     

Partial EBG Structure with DeCap for Ultra‐wideband Suppression of Simultaneous Switching Noise in a High‐Speed System

To supply a power distribution network with stable power in a high‐speed mixed mode system, simultaneous switching noise caused at the multilayer PCB and package structures needs to be sufficiently suppressed. The uniplanar compact electromagnetic bandgap (UC‐EBG) structure is well known as a promising solution to suppress the power noise and isolate noise‐sensitive analog/RF circuits from a noisy digital circuit. However, a typical UC‐EBG structure has several severe problems, such as a limitation in the stop band's lower cutoff frequency and signal quality degradation. To make up for the defects of a conventional EBG structure, a partially located EBG structure with decoupling capacitors is proposed in this paper as a means of both suppressing the power noise propagation and minimizing the effects of the perforated reference plane on the signal quality. The proposed structure is validated and investigated through simulation and measurement in both frequency and time domains.     

3G系统中AGC的FPGA设计实现

详细介绍了数字AGC的基本原理,3G接收机需要采用AGC电路处理输入的无线信号,从而给无线环路中的可变增益放大器或数控衰减器提供外部控制信号,使得无线链路输出基本恒定且与输入信号电平无关的信号给基带部分处理,同时在很宽的范围内保持线性。RF输入电压经IF放大后,检波器检测出该电压的包络。该包络电压经AGC处理后,产生增益可变器件的控制电压,从而减小IF的输入和增益。     

韩国WiBro技术分析

WiBro是当前最新的移动宽带无线接入技术之一,它是由韩国业界开发的一项本土技术。WiBro可看作是移动WiMAX,虽然其技术与标准尚处于不断变化之中。给出了WiBro技术的发展历程和技术定位,提出了WiBro系统的基本构成,详细分析了WiBro系统性能(包括频谱范围、数据速率、QoS、双工模式和调制方法),最后阐述了WiBro技术的应用现状。     

A POMDP‐based long‐term transmission rate maximization for cognitive radio networks with wireless‐powered ambient backscatter

Wireless energy harvesting enables wireless‐powered communications to accommodate data services in a self‐sustainable manner over a long operational time. Along with energy harvesting, an ambient backscatter technique helps a secondary transmitter reflect existing radio frequency (RF) signal sources to communicate with a secondary receiver when the primary channel (PC) is utilized. However, secondary system performance is significantly affected by factors such as the availability of the primary channel, imperfect spectrum sensing, and energy‐constrained problems. Therefore, we propose a novel approach for wireless‐powered cognitive radio networks (CRNs) to improve the transmission performance of secondary systems. To reduce the dependence of the secondary system on RF sources, in the paper, we provide a new paradigm by integrating ambient backscattering with both RF and non‐RF wireless‐powered communications to facilitate secondary communications. On the basis of the sensing result in a time slot, the secondary transmitter can dynamically select the operational action: (a) backscattering, (b) harvesting, or (c) transmitting to maximize the long‐term achievable data transmission rate at the secondary receiver. In addition, the optimal action set for CRNs with wireless‐powered ambient backscatter is selected by the partially observable Markov decision process (POMDP), which maximizes an expected transmission rate calculated over a number of subsequent time slots. The proposed scheme aims to improve long‐term transmission rate of CRNs with wireless‐powered ambient backscatter in comparison with conventional schemes where an action is taken only to maximize the immediate reward in every single time slot.     

Novel Equalization On‐Channel Repeater with Feedback Interference Canceller in Terrestrial Digital Multimedia Broadcasting System

In this paper, we propose a novel equalization on‐channel repeater (OCR) with a feedback interference canceller (FIC) to relay terrestrial digital multimedia broadcasting signals in single frequency networks. The proposed OCR not only has high output power by cancelling the feedback signals caused by insufficient antenna isolation through the FIC, but also shows better output signal quality than the conventional OCR by removing multipath signals existing between the main transmitter and the OCR through an equalizer. In addition, computer simulations and laboratory test results demonstrate that the proposed OCR successfully cancels feedback signals and compensates channel distortions and provides a higher quality transmitting signal with higher output power than conventional OCRs.     

A dual-antenna phase-array ultra-wideband CMOS transceiver

Ultra-wideband (UWB) systems use high-bandwidth signals to enable a new generation of ultra-high-data-rate wireless applications. Implementation of a high-bandwidth RF system in the 3-5 GHz band presents challenges that can be solved by circuit and system techniques. This article looks at the motivation and requirements for a WiMedia-compliant UWB system implemented for a target application in wireless video transmission. It explores the circuit-level trade-offs in CMOS radio and some of the system-level methods, such as selection diversity and equal-gain combining, used to increase robustness in multipath and interference environments. The radio (S. Lo, 2006) is part of a two-chip solution that includes a digital baseband chip that implements the WiMedia-compliant PHY and MAC. The measured results of the 0.18 /spl mu/m CMOS UWB transceiver demonstrate the efficacy of these techniques in the final RF and system performance.     

Cross‐layer optimization for CDMA/TDD wireless mesh networks

This paper proposes a new cross‐layer optimization algorithm for wireless mesh networks (WMNs). CDMA/TDD (code division multiple access/time division duplex) is utilized and a couple of TDD timeslot scheduling schemes are proposed for the mesh network backbone. Cross‐layer optimization involves simultaneous consideration of the signal to interference‐plus‐noise ratio (SINR) at the physical layer, traffic load estimation and allocation at medium access control (MAC) layer, and routing decision at the network layer. Adaptive antennas are utilized by the wireless mesh routers to take advantage of directional beamforming. The optimization formulation is subject to routing constraints and can be solved by general nonlinear optimization techniques. Comparisons are made with respect to the classic shortest‐path routing algorithm in the network layer. The results reveal that the average end‐to‐end successful packet rate (SPR) can be significantly improved by the cross‐layer approach. The corresponding optimized routing decisions are able to reduce the traffic congestion. Copyright © 2010 John Wiley & Sons, Ltd.     

Beamforming‐based feature extraction and RVM‐based method for attacker node classification in CRN

Cognitive radio is a promising technology for the future wireless spectrum allocation to improve the utilization rate of the licensed bands. However, the cognitive radio network is susceptible to various attacks. Hence, there arises a need to develop a highly efficient security measure against the attacks. This paper presents a beamforming‐based feature extraction and relevance vector machine (RVM)‐based method for the classification of the attacker nodes in the cognitive radio network. Initially, the allocation of the Rayleigh channel is performed for the communication. The quaternary phase shift keying method is used for modulating the signals. After obtaining the modulated signal, the extraction of the beamforming‐based features is performed. The RVM classifier is used for predicting the normal nodes and attacker nodes. If the node is detected as an attacker node, then communication with that node is neglected. Particle swarm optimization is applied for predicting the optimal channel, based on the beamforming feature values. Then, signal communication with the normal nodes is started. Finally, the signal is demodulated. The signal‐to‐noise ratio and bit‐error rate values are computed to evaluate the performance of the proposed approach. The accuracy, sensitivity, and specificity of the RVM classifier method are higher than the support vector machine classifier. The proposed method achieves better performance in terms of throughput, channel sensing/probing rate, and channel access delay. Copyright © 2016 John Wiley & Sons, Ltd.     

16‐QAM‐Based Highly Spectral‐Efficient E‐band Communication System with Bit Rate up to 10 Gbps

This paper presents a novel 16‐quadrature‐amplitude‐modulation (QAM) E‐band communication system. The system can deliver 10 Gbps through eight channels with a bandwidth of 5 GHz (71‐76 GHz/81‐86 GHz). Each channel occupies 390 MHz and delivers 1.25 Gbps using a 16‐QAM. Thus, this system can achieve a bandwidth efficiency of 3.2 bit/s/Hz. To implement the system, a driver amplifier and an RF up‐/down‐conversion mixer are implemented using a 0.1 µm gallium arsenide pseudomorphic high‐electron‐mobility transistor (GaAs pHEMT) process. A single‐IF architecture is chosen for the RF receiver. In the digital modem, 24 square root raised cosine filters and four (255, 239) Reed‐Solomon forward error correction codecs are used in parallel. The modem can compensate for a carrier‐frequency offset of up to 50 ppm and a symbol rate offset of up to 1 ppm. Experiment results show that the system can achieve a bit error rate of 10^?5 at a signal‐to‐noise ratio of about 21.5 dB.