一种基于FPGA的MSK调制器设计与实现

首先分析了MSK调制信号的特点以及功率谱,然后根据软件无线电的思想,用可编程器件FPGA实现了基带信号的MSK调制,主要包括串并转换、数字频率合成、基带调制与中频调制等部分.     

C-RAN系统中的软件基带信号处理技术

云无线接入网(C-RAN)是融合了集中化处理、协作无线电和实时云计算的无线接入网架构,不同于传统无线通信网络架构,其基带处理单元基于统一开放的软件无线电平台。本文从灵活性、实现复杂度、运算精确度、处理时延、吞吐量、资源利用率、能耗等方面对比C-RAN系统中的软件发送接收技术与传统基带信号处理技术,并以低密度奇偶校验码(LDPC)编码载波传输系统为典型案例,展示软件技术运算精确度高、性能优良,而传统技术处理时延低的特点。     

Bridging dream and reality: programmable baseband processors for software-defined radio - [integrated circuits for communications]

A programmable radio baseband signal processor is one of the essential enablers of software- defined radio. As wireless standards evolve, the processing power needed for baseband processing increases dramatically and the underlying hardware needs to cope with various standards or even simultaneously maintaining several radio links. Meanwhile, the maximum power consumption allowed by mobile terminals is still strictly limited. These challenges require both system and architecture level innovations. This article introduces a design methodology for radio baseband processors discussing the challenges and solutions of radio baseband signal processing. The LeoCore architecture is presented here as an example of a baseband processor design aimed at reducing power and silicon cost while maintaining sufficient flexibility.     

基于BLF时钟的RFID低功耗数字基带设计

提出了一种符合ISO/IEC 18000-6C协议中关于时序规定的射频识别(RFID)无源标签芯片低功耗数字基带处理器的设计.基于采用模拟前端反向散射链路频率(BLF)时钟的方案,将BLF的二倍频设置为基带中的全局时钟,构建BLF和基带数据处理速率之间的联系;同时在设计中采用门控时钟和行波计数器代替传统计数器等低功耗策略.芯片经TSMC 0.18 μmCMOS混合信号工艺流片,实测结果表明,采用该设计的标签最远识别距离为7 m,数字基带动态功耗明显降低,且更加符合RFID协议的要求.     

Design of Reader Baseband Receiver Structure for Demodulating Backscattered Tag Signal in a Passive RFID Environment

In this paper, we present a demodulation structure suitable for a reader baseband receiver in a passive radio frequency identification (RFID) environment. In a passive RFID configuration, an undesirable DC‐offset phenomenon may appear in the baseband of the reader receiver, which can severely degrade the performance of the extraction of valid information from the received tag signal. To eliminate this DC‐offset phenomenon, the primary feature of the proposed demodulation structures for the received FM0 and Miller subcarrier signals is to reconstruct the signal corrupted by the DC‐offset phenomenon by creating peak signals from the corrupted signal. It is shown that the proposed method can successfully detect valid data, even when the received baseband signal is distorted by the DC‐offset phenomenon.     

A complex baseband platform for spatial-temporal mobile radio channel simulations

Joint spatial-temporal signal processing has been recognized as the key to reducing the effects of the intersymbol and cochannel interference seen in very high bit-rate mobile radio communications systems. Developing hardware simulators that can simulate mobile radio propagation scenarios in time and space domains is essential for evaluating the real-time performance of spatial-temporal signal processing schemes. This paper outlines a complex baseband platform developed for spatial-temporal mobile radio channel simulations. The platform consists of a complex baseband fading/array response simulator, a digital signal processor (DSP) board, and a general-purpose parameter estimator that uses systolic array implementation of the recursive least square (RLS) algorithm. Results of experiments conducted using the developed platform are presented to confirm the proper operation of the system.     

基于TMS320VC5402 DSP的无线通信系统中基带DQPSK调制解调器的研制

提出了一种无线通信中基带调制解调器的设计原理和实现方法。阐述了系统实现的关键硬件技术和系统详细工作过程。飞行实验表明，系统达到设计指标。     

Low-clock-speed time-interleaved architecture for a polar delta–sigma modulator transmitter

The polar delta–sigma modulator (DSM) transmitter architecture exhibits good coding efficiency and can be used for software-defined radio applications. However, the necessity of high clock speed is one of the major drawbacks of using this transmitter architecture. This study proposes a low-complexity time-interleaved architecture for the polar DSM transmitter baseband part to reduce the clock speed requirement of the polar DSM transmitter using an upsampling technique. Simulations show that using the proposed four-branch time-interleaved polar DSM transmitter baseband part, the clock speed requirement of the transmitter is reduced by four times without degrading the signal-to-noise-and-distortion ratio.     

Component-based development of radio systems and subsystems: Are we there yet? [Trends in DSP]

The June 2005 "Trends in DSP" column explored the concept of component-based development for radio systems and subsystems. In this model the intermediate frequency (IF) and baseband signal processing associated with each wireless air interface standard on a given radio product are created from encapsulated software, hardware, and firmware intellectual property (IP) that can be reused from product to product.     

Resource-efficiency improvement based on BBU/RRH associated scheduling for C-RAN

Wireless Networks - Cloud radio access network (C-RAN) is an attractive technology to improve power efficiency through providing a novel architecture of baseband unit (BBU) pool to centrally...     

Design of interfaces between high speed data converters and high performance FPGAs for software defined radio applications

Telecommunication Systems - Software defined radio (SDR) is a vast and emerging field that requires the design of various technologies such as antenna, RF, IF, and digital baseband subsystems....     

基于"中国芯"的SCDMA彩屏手机设计

介绍了核心芯片(基带芯片与射频芯片)采用“中国芯”的SCDMA彩屏手机的设计与应用。对彩屏手机的硬件架构电路进行了介绍,对基带处理部分、射频电路部分、多媒体应用部分等一些主要芯片进行了阐述,并提出了应用国产芯片在SCDMA彩屏手机设计中会出现IO处理问题、映射电压问题、32 kHz时钟电路匹配与PCB设计问题、彩屏屏闪问题,介绍了解决这些问题的技巧。     

NAVDAT接收机硬件设计

叙述了一种基于直接采样架构的NAVDAT接收机设计及实现方案,详述了射频及基带的设计重点,并对接收机硬件进行了初步测试。该方案灵活性强,拓展性好,是后续多系统综合航保一体机设计的基础。     

Network Lifetime Enhancement of Wireless Sensor Networks Using EFRP Protocol

This paper presents a novel transceiver architecture for in-band full duplex radio. A transceiver for full duplex radio requires a self-interference (SI) canceler to remove the SI occurring from the transmitter to the receiver, and a full duplex transceiver generally has two SI cancelers: one at the analog RF stage and the other at the baseband stage. The output from the SI canceler at the RF stage includes much residual SI, and it decreases the number of bits allocated to the analog baseband signal at the analog-to-digital converter. A 1-tap analog baseband SI canceler that uses a replica signal including only the direct path component of the residual SI has been presented for preventing degradation. However, the architecture cannot remove the SI well due to the high Ricial K-factor. To address the problem, the presented architecture has an SI canceler at the analog baseband stage, and this canceler employs a replica signal that is output from a digital-to-analog converter. Because the replica signal is generated in the digital domain, the architecture can generate a multipath replica signal, and improved performance can be expected. Numerical and theoretical analyses are shown to validate the effectiveness of the presented architecture.

     

Impact of RF impairments on a DS-CDMA receiver

This letter provides an analysis of the impact of classical radio frequency (RF) front-end impairments (RF mismatch and direct current (dc) offset) on the performance of direct-sequence code-division multiple-access (DS-CDMA) receivers; such issues are of particular importance in the case of zero intermediate-frequency (Zero-IF) receivers. Using a standard expression of the baseband signals as well as basic properties of spreading codes used in DS-CDMA communications, we show that the consequence of such RF mismatch and dc offset is essentially a degradation of the wanted signal's level and an increase of the noise power. We give closed-form expressions (in E/sub b//N/sub 0/ form) for both. The results are then shown to be in accordance with numerical simulations utilizing the codes of the universal terrestrial radio access in the frequency-division duplex mode downlink standard.     

A Technique of PCM Transmission over 2 GHz Microwave Radio

The application of multiplexed PCM channels to a microwave radio system is attractive in areas where geographic terrain limits the practicality of cable plant construction. A technique of interfacing the digital signal with an analog radio baseband is described. The successful Inclusion of a voice-frequency (VF) orderwire at the low frequency end of the digital spectrum without a significant penalty in error-rate performance demonstrates the efficiency of the technique.     

适用于软件无线电基带芯片验证的实时原型平台

随着半导体芯片器件规模急剧增长,对芯片的功能验证以及场景验证提出了更多的挑战。而对于基带SOC芯片,挑战则更加显著。基带SOC芯片的设计验证涉及到大量算法、信号处理专用电路、软硬件协同、实时复杂场景等功能评估与验证。一般通用的芯片验证方法(基于测试用例的服务器离线验证以及FPGA原型验证)无法覆盖对基带芯片评估、验证以及测试的要求。针对基带芯片设计验证需求,本文设计并实现了一个基于软件无线电的通用实时原型平台,可满足不同频段、不同协议的基带芯片的算法评估、功能及场景测试需求。本文基于该通用实时原型平台,成功的对一款GPS/BD导航基带芯片进行了实时原型验证,解决了原有离线仿真不能满足的实时场景验证需求,使得基带芯片的验证环境更加贴近真实环境,从而极大的提高了芯片的成功率。     

UWB short-range radar sensing - The architecture of a baseband, pseudo-noise UWB radar sensor

The pioneers of radio science made their first trials of wireless information transmission and demonstrated localization of a steel vessel by radio waves more than 100 years ago. Back then, the world of radio frequencies was organized in a very simple way. The researchers could use any frequency band. There was no interference by others and no controlling government bodies. Since then, governmental authorities have established tight regulations that have split up the available frequency band into small partitions for exclusive use. This article discusses the architecture of a baseband, pseudo-noise UWB radar and gives some examples of applications     

Centralized vs. distributed algorithms for resilient 5G access networks

Photonic Network Communications - Cloud radio access networks (C-RANs), relying on network function virtualization and software-defined networking (SDN), require a proper placement of baseband...     

Baseband pulse shaping for π/4 FQPSK in nonlinearly amplifiedmobile channels

We apply baseband pulse shaping techniques for π/4 QPSK in order to reduce the spectral regeneration of the bandlimited carrier after nonlinear amplification. These Feher's patented techniques, namely, π/4 FQPSK (superposed QPSK) and π/4 CTPSK (controlled transition PSK), may also be noncoherently demodulated. Application of these techniques is in fast fading, power efficient channels, typical of the mobile radio environment. Computer simulation and experimental studies demonstrate that with these baseband waveshaping techniques, carrier envelope fluctuations are significantly reduced, and the out-of-band power after nonlinear amplification is suppressed by up to 20 dB compared to π/4 QPSK. In frequency noninterleaved land or satellite mobile radio systems operating in a nonlinear, fading and ACI (adjacent channel interference) environment, these techniques may achieve 20%-50% higher spectral efficiency compared to π/4 QPSK. In mobile cellular systems using π/4 QPSK, such as the new North American and the Japanese digital cellular systems, the application of these baseband pulse shapes may allow more convenient and less costly amplifier linearization