Software radio architecture: a mathematical perspective

As the software radio makes its transition from research to practice, it becomes increasingly important to establish provable properties of the software radio architecture on which product developers and service providers can base technology insertion decisions. Establishing provable properties requires a mathematical perspective on the software radio architecture. This paper contributes to that perspective by critically reviewing the fundamental concept of the software radio, using mathematical models to characterize this rapidly emerging technology in the context of similar technologies like programmable digital radios. The software radio delivers dynamically defined services through programmable processing capacity that has the mathematical structure of the Turing machine. The bounded recursive functions, a subset of the total recursive functions, are shown to be the largest class of Turing-computable functions for which software radios exhibit provable stability in plug-and-play scenarios. Understanding the topological properties of the software radio architecture promotes plug-and-play applications and cost-effective reuse. Analysis of these topological properties yields a layered distributed virtual machine reference model and a set of architecture design principles for the software radio. These criteria may be useful in defining interfaces among hardware, middleware, and higher level software components that are needed for cost-effective software reuse     

软件无线电分层体系结构

介绍一种用来设计可重构平台的软件无线电体系结构,叫做软件无线电分层体系结构。这种结构引入了软件无线电的所有特征,并使复杂的问题简单化,是一个开放的、统一的、正式的体系结构,适合于软件无线电系统的标准化,有利于软件无线电体系结构的统一。     

Adaptability and Configurability in Cognitive Radio Design on Small Form Factor Software Radio Platform

The recent advances in cognitive radio technology based on software defined radio platforms have extended the capabilities of wireless communication systems. The unique ability of cognitive radios to alter their communication protocols to meet changing system demands make them great candidates for wireless applications that are difficult to implement using conventional wireless terminals. Small form factor platforms make cognitive radio portable and easy to deploy. This paper discusses the design and implementation methodology to build a cognitive radio on small form factor platform with heterogeneous processing architecture. The result of this discussion is a configurable wireless transceiver that features two important concepts of cognitive radio, namely configurability and adaptability.     

An overview of configurable computing machines for software radio handsets

The advent of software radios has brought a paradigm shift to radio design. A multimode handset with dynamic reconfigurability has the promise of integrated services and global roaming capabilities. However, most of the work to date has been focused on software radio base stations, which do not have as tight constraints on area and power as handsets. Base station software radio technology progressed dramatically with advances in system design, adaptive modulation and coding techniques, reconfigurable hardware, A/D converters, RF design, and rapid prototyping systems, and has helped bring software radio handsets a step closer to reality. However, supporting multimode radios on a small handset still remains a design challenge. A configurable computing machine, which is an optimized FPGA with application-specific capabilities, show promise for software radio handsets in optimizing hardware implementations for heterogeneous systems. In this article contemporary CCM architectures that allow dynamic hardware reconfiguration with maximum flexibility are reviewed and assessed. This is followed by design recommendations for CCM architectures for use in software radio handsets.     

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.     

电台软件架构发展及其向SCA4．0演进的途径分析

使用标准的软件架构能够实现波形应用的硬件无关设计,也便于电台软件走向分层开放的合作设计。采用软件通信体系结构SCA,能够实现电台软件的标准化、平台化、智能化。首先对SCA在国内外的发展与应用现状进行了介绍,在基于主流的SCA2．2规范进行的SCA电台软件开发经验的基础上,探讨了SCA4．0架构的特点,提出了把核心框架、平台、波形从SCA2．2架构升级到SCA4．0架构的途径,思考了基于SCA架构的电台软件未来发展趋势。     

Enabling Components for Multi-Standard Software Radio Base Stations

Receiver and transmitter technology is an enablingfactor for the software radio concept, with analogueto digital conversion being the limiting performancefactor. The requirement for common hardware forseveral different systems leads to parameterizedmodules and higher integration levels. Moduledefinition is closely related to the architecturalchallenges of receiver design. Emerging multi-mode base stations favour larger hardware granularity. Thesoftware radio approach reduces the hardwarecomplexity of a cell site from several racks ofdiscrete single-channel radios to one or two shelvesof open architecture modules.This paper presents critical functional blocks forwide-band multi-mode base stations based on thesoftware radio concept. Major component specificationsare reviewed showing the implications on systemdesign. Functional and performance parameters foranalogue to digital converters (ADCs), digital toanalogue converters (DACs), digital down and upconverters are illustrated using specific products.Applications are presented by revisiting existingtransceiver architectures in the framework of nextgeneration wireless standards.     

Broadband RF stage architecture for software-defined radio inhandheld terminal applications

Broadband RF is a general-purpose common RF stage for every standard within a set of RF bands. The RF stage architecture presented in this article is suitable for software-defined radios. This article first defines the conceptual scheme of a handheld software defined radio (SDR) terminal, and then describes how the direct conversion principle is applied to the SDR. The discussion focuses on receiver hardware implementation and systematic control     

Applications of Machine Learning to Cognitive Radio Networks

Cognitive radio offers the promise of intelligent radios that can learn from and adapt to their environment. To date, most cognitive radio research has focused on policy-based radios that are hard-coded with a list of rules on how the radio should behave in certain scenarios. Some work has been done on radios with learning engines tailored for very specific applications. This article describes a concrete model for a generic cognitive radio to utilize a learning engine. The goal is to incorporate the results of the learning engine into a predicate calculus-based reasoning engine so that radios can remember lessons learned in the past and act quickly in the future. We also investigate the differences between reasoning and learning, and the fundamentals of when a particular application requires learning, and when simple reasoning is sufficient. The basic architecture is consistent with cognitive engines seen in AI research. The focus of this article is not to propose new machine learning algorithms, but rather to formalize their application to cognitive radio and develop a framework from within which they can be useful. We describe how our generic cognitive engine can tackle problems such as capacity maximization and dynamic spectrum access.     

COGNITIVE RADIOS FOR DYNAMIC SPECTRUM ACCESS - An Agile Radio for Wireless Innovation

We present the details of a portable, powerful, and flexible software-defined radio development platform called the Kansas University Agile Radio (KUAR). The primary purpose of the KUAR is to enable advanced research in the areas of wireless radio networks, dynamic spectrum access, and cognitive radios. We describe the KUAR hardware implementation and software architecture and present example application of the KUAR to modulation, spectrum measurement, channel estimation, and rapid configuration and adaptation. We outline research directions enabled by the KUAR     

Software radios for airborne platforms

Defense contributions to the Programmable Modular Communications System (PMCS) Integrated Product Team (IPT) included designs for an RF module based on software radio configurations useful in airborne systems. Several configurations were examined, analyzers were consolidated, and concepts of operation (CONOPS) were evaluated. Geographic separation of platforms and on-board separation of radio modules have consequences for the remote control of reconfigurable radios. This paper identifies organizational roles in software radio development, characterizes the need for software radios in airborne applications, and highlights those configurations found to be attractive. The methodology, CONOPS, and conclusions are summarized     

小型化低功耗数字平台设计关键技术

对于使用电池供电的背负式或手持电台,电台的平均功率消耗决 定了电台在战场的可运作时间。因此,数字平台的硬件设计和软件设计都必须把电台的大小 、重量和电源（SWAP）的设计作为首要的考虑事项。从动态时钟调整、电源供应调整、操作 模式、工作周期影响、静态和动态电源对比、硬件电源的小型化考虑以及可编程逻辑和ASIC 的设计对比等多方面进行了研究,为构建灵活的软件无线电平台体系结构提供了参考。     

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     

一种软件电台的基带处理架构及频偏估计设计

论述了一种基于DSP的软件无线电台的基带处理架构及频偏估计设计方法。首先介绍了系统硬件方案,然后对DSP软件架构进行了论述,包括帧结构、EDMA通道中断和串口中断处理流程。最后重点介绍了频偏估计的原理和具体实现方法,并给出了测试结果。     

The rapidly deployable radio network

The rapidly deployable radio network (RDRN) is an architecture and experimental system to develop and evaluate hardware and software components suitable for implementing mobile, rapidly deployable, and adaptive wireless communications systems. The driving application for the RDRN is the need to quickly establish a communications infrastructure following a natural disaster, during a law enforcement activity, or rapid deployment of military force. The RDRN project incorporates digitally controlled antenna beams, programmable radios, adaptive protocols at the link layer, and mobile node management. This paper describes the architecture for the RDRN and a prototype system built to evaluate key system components     

基于交换网络分层结构的软件无线电方案

提出的软件无线电方案采用了基于交换网络的分层结构,这种结构使得硬件的配置、可重配置和模块的扩展变得开放、灵活。最后,通过具体的智能天线下行波束形成方案验证这一基于交换网络分层结构的思想。     

Viral Radio

This paper defines a domain of study, some experiments and a research agenda to explore a topic we term viral radio. The premise is that we can make energy- and spectrum-efficient radio communications systems that scale (almost) without bound. We do this by treating the RF signals in a given space as a distributed optimisation process whereby each radio uses the presence of other radios to assist and cooperate in the delivery of messages. Any relaying that occurs is done in the RF domain; we thus eliminate delays normally associated with multi-hop ad hoc networks. Further, we embed the routing decision in the RF processing and view it as a matter of 'flux-propagation' rather than path definition — data is delivered from a source transmitter to the ultimate recipient with some RF amplification provided by any radios that are in the propagation path. Our goal is to develop a simple radio networking architecture organised on an end-to-end design basis. We expect that we can build scalable and efficient real-time telecommunications and broadcast systems that rely on no central radiator or suite of cell towers.     

Virtual radios

Conventional software radios take advantage of vastly improved analog to digital converters (ADCs) and digital signal processing (DSP) hardware. Our approach, which we refer to as virtual radios, also depends upon high performance ADCs. However, rather than use DSPs, we have chosen to ride the curve of rapidly improving workstation hardware. We use wideband digitization and then perform all of the digital signal processing in user space on a general purpose workstation. This approach allows us to experiment with new approaches to signal processing that exploit the hardware and software resources of the workstation. Furthermore, it allows us to experiment with different ways of structuring systems in which the radio component of communication devices is integrated with higher-level applications. This paper describes the design and performance of an environment we have constructed that facilitates building virtual radios and of two applications built using that environment. The environment consists of an input/output (I/O) subsystem that provides high bandwidth low latency user-level access to digitized signals and a programming environment that provides an infrastructure for building applications. The applications, which exemplify some of the benefits of virtual radios, are a software cellular receiver and a novel wireless network interface     

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。     

Direct downconversion of multiband RF signals using bandpass sampling

Abstract-Bandpass sampling can be used by radio receivers to directly digitize the radio frequency (RF) signals. Although the bandpass sampling theory for single-band RF signals is well established, its counterpart for multiband RF signals is relatively immature. In this paper, we propose a novel and efficient method to find the ranges of valid bandpass sampling frequency for direct downconverting multiband RF signals. Simple formulas for the ranges of valid bandpass sampling frequency in terms of the frequency locations of the multiple RF bands are derived. The result can be used to design a multiband receiver for software defined radios.