MB-OFDM超宽带系统的研究

讨论了基于MB—OFDM方案的超宽带通信系统，在此方案中，整个可用频带被分为多个528MHz的子带，每个子带上采用OFDM技术传输信息，数据通过时频码在不同的子带上传输。主要介绍了频带划分，系统参数，实现结构等问题，同DS—CDMA方案进行了比较。最后展望了UWB无线通信的发展前景。     

一种基于多频段OFDM的超宽带通信系统

针对现行的超宽带(UWB)通信系统抗干扰性较弱的特点,在介绍传统的UWB通信系统的解决方案的基础上,提出了一种基于多频段OFDM技术的超宽带通信系统,建立了系统模型。依据对系统的发射机和接收机工作的原理进行了详细的阐述,并给出了相应的数学模型描述。     

Cross-layer enhanced time scheduling for multi-band OFDM UWB networks

Multi-band Orthogonal Frequency Division multiplexing based Ultra Wide-band (MB-OFDM UWB) technology is one of the strong alternatives for high data rate wireless personal area networks (WPANs) with low power consumption. The capacity of such systems is degraded by multi-path fading, shadowing, multi-user interference and noise. To improve system capacity under these adverse effects, in this paper, we devise cross-layer time scheduling methods, Proportional Time Scheduling with Modiano Algorithm (PTS-MA) and Proportional Time Scheduling with Channel State Information (PTS-CSI), in which scheduling and link adaptation are performed using instantaneous bit error probability (IBEP) estimates obtained through Modiano’s algorithm and our novel estimation technique, respectively. We evaluate the performance of the PTS schemes by using numerical experiments. Simulation results suggest PTS-CSI scheduler as the most promising candidate for practical MB-OFDM UWB WPANs with high capacity and fair throughput distribution.     

基于多带OFDM的超宽带通信系统

根据我国频谱资源分配现状和硬件可实现条件,提出了一种基于多带OFDM的超宽带通信系统设计方案,阐述了频率划分方案、信号发送形式、数据包结构、收发机实现框架等系统设计参数,建立了系统模型;就多址接入、抗干扰、抑制信号峰均功率比、信道估计与均衡等关键技术进行研究,提出了基于二级跳频的正交频分多址、正交扩频与比特交织等解决方案.仿真结果表明,基于这种结构的超宽带通信系统在系统容量、误比特率性能、抗干扰、信号峰均功率比等方面具有诸多的优势.     

一种采用多天线的OFDM超宽带通信系统的性能分析

本文首先研究了在典型室内信道下基于OFDM技术的超宽带（UWB）通信系统的性能，并提出了一种接收能量模型。在此基础上，推广到多天线的情况，得到了基于该系统的误码率表达式。最后，通过仿真验证了分析结果。结果表明本文的分析方法是准确合理的，天线的数目对系统性能有较大的影响     

OFDM发射机设计与FPGA实现

为使OFDM(正交频分复用)技术在宽带无线通信中得到实际运用,提出了基于IEEE 802.11a协议的OFDM发射机的设计方案及关键技术的实现方法。在设计中采用自顶向下的设计思想,通过数字锁相环、乒乓RAM(随机存储器)等方式提高系统运行的可靠性。并利用Altera公司的Cyclone IV E系列FPGA(现场可编程门阵列)器件的特点和灵活的IP Core(知识产权核)功能,实现了OFDM发射机的设计。在Modelsim环境下的仿真结果证明了该设计的有效性,且占用的资源少。     

高速多带NGI-OOFDM传输系统中的非对称发射机与接收机设计

在高速多带无保护间隔(NGI)光正交频分复用(OOFD M)传输系 统中,采用非对称发射机/接收机结构,对接收信号通过多个通用光相干接收机进行部分探 测,可一次完整 接收整个多带NGI-OOFDM信号。发射端采用单个激光源,通过差分马赫曾德尔外调制器产生 8根等频率 间隔为28GHz的光频梳作为光子载波,经112 Gbit/s PDM-QPSK信号调制,波分复用后形成8路宽带的全 光NGI-OOFDM信号。接收端采用非对称发射机/接收机结构,即采用4个接收带宽为 18GHz的通用光相 干接收机,每个接收机接收2路子载波,可以完整接收整个多带NGI-OOFDM信号。采用本文 结构的高速多 带NGI-OOFDM传输系统,误码率(BER)为10－3时, 光信噪比(OSNR)代价较单载波112Gbit/s PDM-QPSK系 统多约9dB。 经16,0ps/nm光纤色散及偏振扰动,在系统接收端通过电色散补偿 后,约有 0.2dB OSNR代价。最后 对传输13×80km的光纤链路进行了仿真,仿真结果表明,与背靠背 情况相比,在进行电色散补偿后,OSNR代价约1.5dB。     

A novel UWB low noise amplifier for multi-band navigation application

Multi-band navigation receivers have been widely applied in mobile communication systems, and the low noise amplifier (LNA) is an important part of navigation receiver. This paper presents a broadband LNA based on balanced amplifier technique in order to get high gain, low noise figure and smaller size. To improve the LNA's stability, we use microstrip lines to replace traditional small inductors and achieve good results. The simulation and measurement results show that the LNA using balanced amplifier technique is absolutely stable with in the band range of 1.1–1.7 GHz, which can include the band of GPS, GLONASS, Galileo and BeiDou satellite navigation systems. Simulation and experimental results are described detailed.     

A highly sustainable multi-band orthogonal wavelet code division multiplexing UWB communication system for underground mine channel

The underground mine channel is highly hostile for communication. A sustainable communication system is required to be integrated as a multipurpose system capable of transferring all types of information such as data, voice and video on identical infrastructure. With its large bandwidth, the Ultra Wide Band (UWB) provides a promising solution to satisfy these requirements. The Multi-Band Orthogonal Frequency Division Multiplexing (MBOFDM) UWB system provides high resilience to Inter-Symbol Interference (ISI) caused by multipath fading channels. This study compares the performance of various existing multi-band UWB systems in the IEEE UWB channel and underground mine channel: MBOFDM, Multi-Band Orthogonal Frequency Code Division Multiplexing (MBOFCDM) and Multi-Band Orthogonal Wavelet Division Multiplexing (MBOWDM). Further, the application of 2D spreading to the MBOWDM UWB system is attempted, and as a result, the Multi-Band Orthogonal Wavelet Code Division Multiplexing (MBOWCDM) UWB system is proposed. The performance of the MBOWCDM system in the IEEE UWB channel and underground mine channel is investigated. The performance of the MBOWCDM UWB system is observed to be superior to those of other multi-band UWB systems. Moreover, the MBOWCDM UWB system supports a higher data rate with low complexity and lower overheads.     

Optimal transmissions for space-time coded OFDM UWB systems

1 Introduction Recently, the high rate short range wireless personal area network (WPAN) is considered. When the inverse of the sampling rate is significantly shorter than the total delay spread, as is the case for most UWB communication systems, OFDM systems are more attractive than a single-carrier system. The multi-band OFDM physical layer proposal has been adopt by IEEE 802.15.3a Task Group[1]。 Combing STC and OFDM have the properties to achieve high data rate and mitigate int…     

Interference suppressing OFDM UWB system with multiple users and MMSE receivers

In this letter we extend the use of interference suppressing (IS) OFDM UWB system from single user to multiuser scenarios. Multiple access capabilities are obtained by employing Multi-Carrier (MC) CDMA in the transmitter along with MMSE multiuser receivers. We illustrate the performance of the multiuser IS-OFDM UWB system with numerical results obtained from simulations.     

A polar modulator transmitter for GSM/EDGE

This 0.5-/spl mu/m SiGe BiCMOS polar modulator IC adds EDGE transmit capability to a GSM transceiver IC without any RF filters. Envelope information is extracted from the transmit IF and applied to the phase-modulated carrier in an RF variable gain amplifier which follows the integrated transmit VCO. The dual-band IC supports all four GSM bands. In EDGE mode, the IC produces more than 1 dBm of output power with more than 6 dB of margin to the transmit spectrum mask and less than 3% rms phase error. In GSM mode, more than 7 dBm of output power is produced with noise in the receive band less than -164 dBc/Hz.     

适用于OFDM UWB 系统的低功耗，大锁定范围注入锁定分频器

This paper describes a divide-by-two injection-locked frequency divider （ILFD） for frequency synthesizers as used in multiband orthogonal frequency division multiplexing （OFDM） ultra-wideband （UWB） systems. By means of dual-injection technique and other conventional tuning techniques, such as DCCA and varactor tuning, the divider demonstrates a wide locking range while consuming much less power. The chip was fabricated in the Jazz 0.18μm RF CMOS process. The measurement results show that the divider achieves a locking range of 4.85 GHz （6.23 to 11.08 GHz） at an input power of 8 dBm. The core circuit without the test buffer consumes only 3.7 mA from a 1.8 V power supply and has a die area of 0.38×0.28 mm^2. The wide locking range combined with low power consumption makes the ILFD suitable for its application in UWB systems.     

OFDM系统的基带自适应预失真器设计

针对OFDM系统中功率放大器的非线性,设计了一种功放自适应预失真器,提出了基于内插环路的同步处理、RASCAL算法的自适应查询表预失真技术。增加同步误差判定模块以及查询表刷新判定模块,保证系统在同步误差波动情况下可靠工作,实现了系统的自适应处理。仿真表明该方法可以在同步误差波动情况下将OFDM系统发射机功率谱泄露改善约17 dB。     

Low-power wide-locking-range injection-locked frequency divider for OFDM UWB systems

This paper describes a divide-by-two injection-locked frequency divider (ILFD) for frequency synthesizers as used in multiband orthogonal frequency division multiplexing (OFDM) ultra-wideband (UWB) systems. By means of dual-injection technique and other conventional tuning techniques, such as DCCA and varactor tuning, the divider demonstrates a wide locking range while consuming much less power. The chip was fabricated in the Jazz 0.18 μm RF CMOS process. The measurement results show that the divider achieves a locking range of 4.85 GHz (6.23 to 11.08 GHz) at an input power of 8 dBm. The core circuit without the test buffer consumes only 3.7 mA from a 1.8 V power supply and has a die area of 0.38 × 0.28 mm2. The wide locking range combined with low power consumption makes the ILFD suitable for its application in UWB systems.     

一种用于短距离无线通信并集成频率合成器的多模式多频带发射机

A reconfigurable multi-mode direct-conversion transmitter(TX) with integrated frequency synthesizer(FS) is presented. The TX as well as the FS is designed with a flexible architecture and frequency plan, which helps to support all the 433/868/915 MHz ISM band signals, with the reconfigurable bandwidth from 250 kHz to 2 MHz. In order to save power and chip area, only one 1.8 GHz VCO is adopted to cover the whole frequency range. All the operation modes can be regulated in real time by configuring the integrated register-bank through an SPI interface. Implemented in 180 nm CMOS, the FS achieves a frequency coverage of 320-460 MHz and 620- 920 MHz. The lowest phase noise can be -107 dBc/Hz at a 100 kHz offset and -126 dBc/Hz at a 1 MHz offset. The transmitter features a C10:2 dBm peak output power with a C9:5 dBm 1-dB-compression point and 250 kHz/500 kHz/1 MHz/2 MHz reconfigurable signal bandwidth.     

基于OFDM的UWB系统研究

UWB无线通信是未来最富有竞争力的无线通信技术之一。介绍了一种基于正交频分复用的超宽带(OFDM-UWB)系统的结构,详细分析了电路的主要构成:模数转换器、低噪声放大器、脉冲发生以及他们和系统功耗的联系;介绍了OFDM-UWB信号的处理过程,并探究了消除接收到的UWB信号中窄带干扰(NBI)信号的方法,该方法有效地提高了OFDM-UWB系统的抗干扰性。     

A sideband-suppressed fast-hopping synthesizer for dual-carrier OFDM UWB transceivers

A sideband-suppressed China UWB Standard synthesizer which is able to generate two carriers simultaneously is presented. An efficient synthesizing technique with a single quadrature phase-locked loop (QPLL) is proposed for fast band switching. To suppress accumulating sidebands at the outputs, a clock buffer with I/Q calibration and distortion cancellation technique is proposed. Fabricated in TSMC 0.13-μm CMOS technology and operated at 1.2 V, the synthesizer measures a maximum sideband rejection of 45 dB and a phase noise of ?105 dBc/Hz at 1-MHz offset. The synthesizer covers frequency range from 6.2 to 9.4 GHz with band switching time less than 1.4 ns.     

IMM-based Kalman filter for channel estimation in UWB OFDM systems

Ultra-wide band (UWB) communication is one of the most promising technologies for high-data rate wireless networks for short-range applications. This paper proposes a blind channel estimation method namely Interactive Multiple Model (IMM)-based Kalman algorithm for UWB OFDM systems. IMM-based Kalman filter is proposed to estimate frequency selective time-varying channel. In the proposed method, two Kalman filters are concurrently estimating channel parameters. The first Kalman filter, namely the Static Model Filter (SMF) gives an accurate result when the user is static while the second Kalman filter namely the Dynamic Model Filter (DMF) gives an accurate result when the receiver is in moving state. The static transition matrix in SMF is assumed as an Identity matrix where as in DMF, it is computed using Yule–Walker equations. The resultant filter estimate is computed as a weighted sum of individual filter estimates. The proposed method is compared with other existing channel estimation methods.     

A complementary codes pilot-based transmitter diversity technique for OFDM systems

This letter presents a complementary codes pilot-based space-time block code/orthogonal frequency division multiplex (STBC/OFDM) system. In this system, a pair of complementary codes transmitted in a pre-defined order with the OFDM data signals is used as the pilot signals in a two-antenna transmitter diversity system, and used to estimate the channels for optimal data detection at the receiver side. A complete receiver architecture has been designed and Monte Carlo simulations have been used to verify the performance of the system in mobile radio fading channels.