Seamless Dynamic Runtime Reconfiguration in a Software-Defined Radio

We discuss implementation aspects of a software-defined radio system that allows for dynamic waveform reconfiguration during runtime without interrupting data-flow processing. Traditional software-defined radio systems execute a waveform statically, exactly as it is programmed. Reconfiguration is provided by executing a different waveform, which requires the system to stop processing data while reconfiguration occurs, and also may incur an unacceptable delay for some applications. Recent research has demonstrated basic reconfiguration by programming multiple branches into a waveform and dynamically switching between branches. This technique requires redundant resources and in general cannot be expanded to encompass all possible waveforms of interest, but, if implemented carefully, could be made to seamlessly process data. We propose a system that allows for dynamic insertion and removal of entire waveforms, individual constituent blocks, and block algorithm implementations tailored to specific processors. Our system performs this reconfiguration while maintaining processing state, seamlessly without interrupting data-processing, and with only the resources necessary for the given waveform and processors. In order to leverage this new level of reconfigurability, we created a new system component: a supervisor. This system supervisor monitors the state of each processor and waveform execution, and moves computations among available processors as their loads, capabilities, and block algorithm implementations allow. An example using a simple supervisor is provided to demonstrate the effectiveness of our system.     

SCA架构软件无线电台设计与实现

为提高数字通信电台的通用性、灵活性和重构性,提出了一种基于软件通信体系结构（SCA）的软件无线电台的设计方案,给出该方案的工程实现方法,并以超短波跳频波形为例讲述了基于该软件无线电台的应用波形和组件的开发过程。该方案可为基于SCA架构的便携式软件无线电台的设计和开发提高参考。     

基于FPGA芯片的机载波形动态重构设计

针对机载综合射频传感器系统高度综合化的实际需求，基于部分可重构技术提出了一种机载传感器功能波形重构设计方法，以实现在现场可编程门阵列（Field Programmable Gate Array，FPGA）芯片局部区域上时分复用机载功能波形。该方法引入一种便于功能波形移植部署的FPGA平台设计，并在此平台上完成机载功能波形在FPGA芯片局部区域的可重构具体设计。工程应用表明，该设计能够灵活有效复用可编程逻辑器件资源，提高了综合射频传感器系统的功能波形集成度，具有较好的实践意义。     

Open Architecture Standard for NASA's Software-Defined Space Telecommunications Radio Systems

NASA is developing an architecture standard for software-defined radios used in space- and ground-based platforms to enable commonality among radio developments to enhance capability and services while reducing mission and programmatic risk. Transceivers (or transponders) with functionality primarily defined in software (e.g., firmware) have the ability to change their functional behavior through software alone. This radio architecture standard offers value by employing common waveform software interfaces, method of instantiation, operation, and testing among different compliant hardware and software products. These common interfaces within the architecture abstract application software from the underlying hardware to enable technology insertion independently at either the software or hardware layer. This paper presents the initial Space Telecommunications Radio System architecture for NASA missions to provide the desired software abstraction and flexibility while minimizing the resources necessary to support the architecture.     

Flexible and efficient hardware platform and architectures for waveform design and proof-of-concept in the context of 5G

Several technical contributions are emerging nowadays to fulfill the new requirements foreseen in the 5th generation (5G) of mobile communication systems. Among these contributions, different variants of waveform design are proposed for the new radio air interface as alternative to orthogonal frequency-division multiplexing (OFDM) adopted in 4G. However, in order to prove the feasibility and the benefits of the proposed waveforms, practical hardware implementations are necessary. This paper presents one of the first flexible and efficient hardware platforms for waveform design and proof-of-concept. The proposed platform constitutes a complete hardware/software development environment, with digital processing, radio frequency boards, and all associated interfaces for control, communication, and display. Furthermore, the proposed platform allows the support of several communication scenarios as foreseen in 5G. Promising waveform candidates are implemented, in addition to OFDM, with careful architectural choices to allow fair comparisons. Particularly, this paper presents novel hardware architectures for the UF-OFDM transmitter and receiver.     

一种新的智能无线技术——认知无线电技术

认知无线电技术(CR——cognitiveradio)是软件无线电技术的演化,是一种新的智能无线通信技术。它可以感知到无线电传输的环境特征,通过无线电知识描述语言与通信网络进行智能交流,来调整其传输参数,使系统的无线规则满足用户通信最佳性能的需求。文章对认知无线电技术进行了较详细介绍,包括其概念、通信特点、工作过程和部分关键技术等,最后指出了未来认知无线电技术的若干重要发展方向。     

A smart software radio: concept development and demonstration

A testbed system was developed for smart networking radio algorithms. The associated modular software environment and Phase I hardware testbed are described. It provides the framework for the development of advanced processing algorithms, adaptive multirate systems, and operational radio algorithms and modules. Modular software radio technology allows for the insertion of new algorithms, the quantitative characterization of waveform performance, and the separation of the waveform definition from the details of the implementation to enhance portability. The testbed is representative of SPEAKeasy II-class open architecture software radios. The FLIPWAVE spread-spectrum modem invented at the US Air Force Research Laboratory (AFRL) was developed and evaluated using this testbed. The waveform is presented with experimental results. A unique feature of this modem is a new single-channel quadraphase differential RAKE receiver processor, which illustrates the contributions of the testbed toward the flexibility and portability of novel modems     

Diagnosis of Inconsistency in Contracts using Design by Contract

Design by contract allows to develop more reliable and robust applications. Software is reliable if it can perform its work as it was specified, and it is robust if it can control abnormal situations. In this paper it is proposed a methodology to diagnose errors (bugs) in software. It is based on the combination of design by contract, model based diagnosis and constraint programming. Contracts are specified in the design by contract using asserts. These asserts with an abstraction of the source code are transformed into constraints, and these constraints compose the system model. A goal function is established according to the constraints of the system model. With this function is possible to detect which asserts or source code blocks are incorrect. It is proposed a typical diagnosis problem with the design by contract and the source code. The originality of this work is based in the transformation of contracts and source code to constraints in order to obtain which asserts and source code blocks are not consistent with the specification. To obtain these results it is proposed a novel methodology that automatize this task using constraint programming.     

软件无线电基带处理系统的DSP实现

给出了一种基于DSP技术实现的软件无线电基带处理系统，包括一个DSB模拟调制系统和一个FSK数字调制系统，并对软件无线电在移动通信领域的应用进行了探讨。     

Component-based waveform development: the Nucleus tool flow for efficient and portable software defined radio

With the advent of multi-processor systems on chip (MPSoCs) and due to the complexity and variety of modern wireless standards, academia and industry are moving towards software defined radio (SDR) solutions. It is the goal of the SDR approach to allow designers to describe a radio standard or waveform by means of a high level language. This allows faster waveform development cycles and makes it easier to migrate waveforms across different platforms. Out of many software paradigms, component-based software engineering (CBSE) is an attractive match for SDR, especially for baseband applications. It abstracts waveforms in the traditional way algorithm designers think of their applications and guarantees a high degree of portability. However, existing CBSE approaches for SDR have not been able to close the gap between specification and implementation so as to achieve the computational performance and the energy efficiency of handcrafted solutions. The main reason for this gap is that these flows rely on traditional compilers to lower the high level specification to the platform. The work presented in this paper builds on the Nucleus Concept (Ramakrishnan et al., IEEE Military Communications Conference (MILCOM 2009) [28]) in which computationally intensive kernels and their implementation characteristics on the target platform are known. This information allows a tool to close the performance gap, and thus enables efficient component-based SDR development. In this paper we present such a flow and its supporting environment, which includes state-of-the-art tools for system level design. The flow is demonstrated on a MIMO OFDM transceiver.     

Design and rapid prototyping of SCA-compliant public safety P25 waveform and P25?CFM3TR?CVoIP bridge

Establishing radio communication between military commanders, soldiers and law enforcement officers is an important enabling capability to facilitate interoperability. The Joint Tactical Radio System (JTRS) program is enabling communications within the military by implementing different military radio waveforms on software defined radio (SDR) platforms. It is logical to include a Project 25 (P25) public safety waveform in the JTRS waveform portfolio. This paper describes the rapid development of a P25 waveform on a surrogate JTRS SDR platform. The development process and methodology, which starts from a platform agnostic executable waveform model in Matlab, through an intermediate implementation using open tools on generic platforms, to the final platform-specific implementation, is introduced and discussed. This paper shows that adopting this methodology can speed up waveform development and porting. Furthermore, this paper presents the design and implementation of a three way voice bridge among P25, the future multiband multiwaveform modular tactical radio (FM3TR), and voice over Internet Protocol (VoIP), with software communication architecture (SCA) compliant implementation for both the P25 and FM3TR waveforms. This paper shows that critical issues such as interoperability can be tackled efficiently by leveraging SDR and SCA.     

北斗系统信号时域波形失真评估

卫星导航信号时域波形是空间信号质量监测和评估(SQM)的重要内容,本文利用大口径天线接收系统采集的离线数据对北斗IGSO-6卫星B1频点信号时域波形进行分析。首先提出利用基于码相位平均方法求取高信噪比的时域波形,在此基础上利用标准码片波形相关技术提取出码元波形。然后建立相关函数和码元波形的统计理论联系,利用码元波形相关函数差分析信号边沿特性,最后在时域波形上计算出所有北斗卫星的数字失真量,详细评估不同卫星数字失真规律。     

时间调制阵列天线的非理想波形调制研究

针对时间调制阵列天线中射频开关的非理想特性,开展了多种波形调制下的谐波特性研究.首先,推导了非对称梯形波/升余弦波周期调制的傅里叶系数,分析两种调制波的非对称性对各次谐波的幅度、相位和能量占比的影响;在此基础上,通过实验获得了一组实验调制波,并运用三角函数多项式拟合真实调制波形的上升沿与下降沿;最后,讨论了各种波调制与实测谐波分量的差异性.结果表明,与已有调制波相比,本文所提出的非对称梯形波、非对称升余弦波和拟合波的调制更接近真实波调制.     

Estimation of the aortic pressure waveform and beat-to-beat relative cardiac output changes from multiple peripheral artery pressure waveforms

We introduce a patient- and time-specific technique to estimate the clinically more relevant aortic pressure (AP) waveform and beat-to-beat relative changes in cardiac output (CO) from multiple peripheral artery pressure (PAP) waveforms distorted by wave reflections. The basic idea of the technique is to first estimate the AP waveform by applying a new multichannel blind system identification method that we have developed (rather than the conventional generalized transfer function) to the PAP waveforms and then estimate the beat-to-beat proportional CO by fitting a Windkessel model to the estimated waveform in which wave distortion should be attenuated. We present an evaluation of the technique with respect to four swine datasets including simultaneous measurements of two peripheral AP waveforms, a reference AP waveform, and reference aortic flow probe CO during diverse hemodynamic interventions. Our results show an overall AP waveform error of 3.5 mmHg and an overall beat-to-beat CO error of 12.9% (after a single CO calibration in each animal). These estimation errors represent substantial improvements compared to those obtained with several alternative PAP waveform analysis techniques. With further successful testing, the new technique may ultimately be employed for automated and less invasive monitoring of central hemodynamics in various cardiovascular patients.     

A software-defined radio FPGA implementation of OFDM-based PHY transceiver for 5G

This paper introduces a software-defined radio implementation of an OFDM-based transceiver for the prototyping and testing of 5G physical layer algorithms. The implementation uses high level abstraction tools to develop and test the algorithms, significantly reducing the time and effort needed to test new features. The proposed architecture adopts interconnecting FIFOs between each functional block, reducing the critical paths and enabling complex designs to be implemented at higher clock rates. The proposed LTE-like transceiver is implemented using COTS FPGA and RF development boards. The real-time over-the-air demonstrator has an on-the-fly scalable bandwidth from 20 to 61.44 MHz, attaining close to 500 Mb/s when using 256-QAM modulation.     

OCDMA and OSTBC based VLC transceiver design using NI cDAQ

Visible light communication (VLC) is a novel technology especially for short-range data communication. IEEE has standardized VLC for 5G systems as a means to short-range wireless communication. In this paper, a complete state-of-the-art VLC software-defined radio is designed using NI cDAQ components tools developed in LabVIEW/MATLAB. The main objectives in designing a VLC transceiver are the suitable envelope for driving LEDs (transmitters) and a high data rate. The current work makes use of optical code division multiple access mainly to achieve the said objectives. It is shown through comparison with existing system that the proposed system is computationally less expensive and provides improved data rate. Finally, simulation programs are also developed and the proposed system is compared with the existing system in terms of bit error rate.     

Phase-Only Matched Filtering of Ultrawideband Arbitrary Microwave Waveforms via Optical Pulse Shaping

We demonstrate compression of ultrawideband (UWB) microwave arbitrary waveforms via phase-only matched filtering implemented in a programmable hyperfine resolution optical pulse shaper. We synthesize spread-time UWB electrical waveforms and utilize programmable microwave photonic phase filters to impose the opposite of a waveform's spectral phase on its spectrum. This enables us to compress an UWB microwave waveform to its corresponding bandwidth-limited pulse duration via phase filtering. As an example, we present compression of a linear frequency-modulated electrical waveform with ${>}15$ GHz frequency content with almost 200% fractional bandwidth with ${sim}733$ ps temporal window to a 40-ps duration pulse with more than 14-dB gain in peak power. Our technique is programmable and we believe it is applicable to a wide range of arbitrary spectral phase modulated UWB radio frequency (RF) waveforms.      

新一代航空数据链端机的SCA架构设计

新一代航空数据链端机发展技术需求和SCA自身技术优势具有高度的一致性,研究SCA技术在设备中的设计实现具有重要意义.通过系统抽象模型构建、SCA设备开发流程分析以及流程中相应的系统构件化建模、域描述文件产生、应用安装部署、波形开发等关键设计,提出了数据链端机设备的SCA架构设计实现方法.     

光电编码器两种精码波形细分方法原理误差对比

光电编码器通常利用细分两路正交的码盘精码信号达到高分辨力的目的,为使细分技术更加完善,对基于三角波和基于正余弦波的两种细分方法进行了专题研究。分别对理想信号中存在直流误差、幅值误差、基波相位误差、高次谐波误差几种典型误差情况进行了分析,比较两种基于不同波形细分方法的抗干扰能力。实验对精码信号介于正余弦波和三角波之间的编码器进行测试,对于同一台编码器,采用正余弦波细分时精度为36,采用三角波细分时精度为42。结果表明:基于正余弦波的细分方法抗干扰能力优于基于三角波的细分方法。对于高精度光电编码器研制和生产时,可利用正余弦波对精码信号进行细分或将实际信号校正至标准正余弦波再细分。