一种宽频段软件无线电平台的设计与实现

针对现代战术通信中背负式或手持电台体积小、功耗小和对不同频段信号兼容性好的应用需求,结合零中频采样和射频直接采样技术,设计了一种可覆盖较宽通信频段的软件无线电平台。通过将模数和数模转换模块与数字信号处理模块集成在一块印制板上,大大减小了该平台的体积。通过平台软件架构的设计,保证不同通信波形体制的实现。最后,通过调频(Frequency Modulation, FM)和正交相移键控(Quadrature Phase Shift Keying, QPSK)波形测试验证了该平台整个频段信号通信性能良好。该平台具有通信频道宽、结构简单、可靠性高等优点,满足小型化、低功耗和对不同频段信号具有高兼容性的使用需求。     

The implementation of channel diversity in mobile software radio receivers

A novel channel diversity concept is proposed and demonstrated, which avoids receiving signal deterioration due to multipath fading in mobile receivers. The system is based on coherent superposition of the signals received from several transmitters supplying the same information at different frequencies. Based on a software radio architecture this concept may increase the quality of mobile reception in modern car receivers considerably. Compared with multiantenna-receivers which overcome the multipath fading problem by simultaneously receiving the same program with several antennas, the proposed solution is advantageous, since it requires only a single antenna.     

一种可植于软件无线电的低功耗可编程增益放大器

本文提出了一种新的技术,用于优化可编程增益放大器的带宽和功耗的关系。这个可编程增益放大器由三级级联的放大器组成,每一级放大器包括可变增益放大器和直流失调电压消除电路。在消除直流失调的电路中,高通的截止频率可从4 kHz到80 kHz变化。可编程增益放大器芯片使用0.13微米的工艺加工,测试结果表明增益可以从-5dB到60dB连续可调。在 60dB增益模式下,当带宽可从1MHz到10MHz变换,电路消耗的功耗为0.85mA到3.2mA,电源电压为1.2V。它的带内OIP3值为14dBm。     

Design and implementation of UWB CMOS LC filters LNA for carrier less impulse radio receivers

The design and the implementation of Ultra-wide-band (UWB) CMOS LC filter LNA for Ultra Wide Band carrier less Impulse Radio receivers is presented. Architectures for both single ended and differential ended LNA are proposed for small fractional bandwidths such as the ECC frequency band and for large fractional bandwidths such as FCC frequency band. Simple guidelines to achieve large voltage gain and low noise figure are given. The implementation in standard CMOS technologies in the context of integrated receivers is discussed and simple layout rules allowing reliable designs are proposed. Several LNA prototypes for different fractional bandwidths have been fabricated in a 0.13 μm CMOS technology. Measurement results agree well with the simulations.     

Advances in software defined radio

Progress in software defined radio has been rapid, since the term was first coined in the mid 1990s. In this brief overview we summarise some of the recent advances in software defined radio from a range of technology perspectives — radio frequency design, baseband reconfigurability, reconfigurable applications and protocols and regulatory (and related network) aspects. Our frame of reference for this article is commercial mobile telecommunications, although many of the technology advances are of relevance and application in other arenas, such as defence, satellite communications and broadcasting. Software defined radio has come a long way very quickly, but in reality is still in its infancy — the next decade will see substantially further advances. This paper draws heavily upon two books on this subject recently edited by the author — the contributors to those books are listed at the end of this article and the work of these pioneers of software radio is fully and most gratefully acknowledged. Additional detail on issues covered in this article may be found in specific chapters of these books, referenced as [Name] within the text.     

A current-mode continuous-time filter for software defined radio solutions

A 3rd-order continuous-time current-mode filter in 65 nm CMOS technology is presented. The filter has a switchable cut-off frequency between 1.1 and 4.4 MHz and is designed for software defined radio on chip (SDR) solutions. An innovative extension to structures in literature is proposed, that allows saving chip area at low cut-off frequencies. Furthermore a mathematical estimation is presented to show the usability of the structure. The realized chip has an active area of 350 μm × 220 μm and consumes 12.3 mW at 1.2 V. The dynamic range for a bandwidth of 1.1 MHz is 77.2 dB, the in-band output current noise is \(31.16\,\hbox{pA}/\sqrt{\hbox{Hz}}\) and the IIP3 is 1.8 mA_p.     

Design of high-speed digital filters suitable for multi-DSP implementation

A multipath signal processing scheme is proposed to overcome the limitation on throughput rate of present-day LSI devices using a number of digital signal processors. Two methods are proposed to realize a given transfer function H(z) for a digital filter with a throughput rate speed that is N times higher than in conventional methods. The first method, the delayed multipath approach, uses an N-path structure as a building element. These N elements are connected successively with increasing delay units to realize a given transfer function. The second method preprocesses the input signal sequence with an FFT processor and follows it up by N of constituent transfer functions derived from H(z) having real coefficients. The output of these N constituent transfer functions is finally post processed by an inverse FFT processor to obtain the desired output signal. The number of the constituent transfer functions is double for a special case when the transfer function to be implemented has complex valued coefficients.     

软件无线电跳频电台接收机射频前端设计

基于软件无线电的基本要求和发展趋势,提出了一种应用在软件无线电跳频电台中接收机射频前端电路结构,分析了接收机射频前端的总体设计方案,包括前端各部分增益的分配、动态范围的分配、噪声系数及灵敏度的计算,讨论了对器件选择的考虑.实际测试结果表明,该射频前端性能指标满足设计要求.     

Jitter requirements of the sampling clock in software radio receivers

The effective number of bits of an analog-to-digital converter (ADC) is not only limited by the quantization step inaccuracy but also by sampling time uncertainty. According to a commonly used model, the error caused by timing jitter, integrated over the whole bandwidth, should not be bigger than the quantization noise, for a full swing input signals at the maximum input frequency. This results in unfeasible phase noise requirements for the sampling clock in software radio receivers with direct RF sampling. However, for a radio receiver not the total integrated error is relevant, but only the error signal in the channel bandwidth. This paper explores the clock jitter requirements for a software radio application, using a more realistic model and taking into account the power spectrum of both the input signal and the spectrum of the sampling clock jitter. Using this model, we show that the clock jitter requirements are very similar to reciprocal mixing requirements of superheterodyne receivers.     

Mode switching and software download for software defined radio:the SDR Forum approach

The proliferation of air interfaces has created the need for a standard way of switching services supported by a wireless system and downloading new code to systems in the field. Both conventional and software defined systems need this capability. This article describes the work of the SDR Forum in developing such a switcher/downloader standard     

Adaptive prediction and cancellation digitization method for wideband multistandard software radio base-station receivers

In this study, a new method for digitizing a combination of different analog signals occupying significantly different bandwidths and having a very high dynamic range is proposed and analyzed. Since it is based upon signal-prediction/cancellation principles, it is referred to as adaptive prediction and cancellation digitization (APCD) method and is applied to various families of signals simultaneously received by a multistandard software radio (SWR) base-station receiver. It is shown theoretically and by means of computer simulations that the APCD method can effectively reduce the high dynamic range of the signals before digitization takes place. Hence, the stringent analog-to-digital-converter (ADC) resolution requirements imposed by the operation of such SWR base-station receivers can be significant relaxed. The signal dynamic-range reduction is achieved by applying appropriate signal processing techniques, e.g., autoregressive (AR) and periodic autoregressive (PAR) prediction. Such techniques allow accurate prediction and subsequent cancellation of high-power narrowband signals present among the composite received analog signal. As these signals usually have cyclostationary statistical characteristics, analysis and performance evaluation of AR and PAR predictors, when used to predict cyclostationary signals, were presented. A new adaptive algorithm for implementing the PAR predictor is also proposed, and its validity is justified by theoretical analysis as well as by various performance evaluation results obtained by means of computer simulations.     

A software defined radio modeling framework for enabling cognitive applications

The rapid advances in software defined radio (SDR) technologies over the past decade encouraged their transition from the lab to field deployment, and shifted the usage from disparate communication devices to the creation of large resilient wireless networks capable of adapting to highly variable environment conditions in a cognitive manner. Simulation models capable of accurately representing the behavior and properties of SDR devices operating in a networked environment thus become a prerequisite for both the evaluation of such networks as well as for providing a development platform for creating new cognitive capabilities. This paper describes our work in creating a network simulation model framework for software defined radios that takes into account some of the unique behaviors and requirements of SDRs not previously seen in purely hardware devices. Factors such as large and variable communication delays between software modules, contention to shared resources, such as CPU or memory, as well as continuous tuning and environment awareness functionality essential to SDR demand a different modeling approach as well as novel techniques that enable accurate scale testing.     

RF direct orthogonal phase under-sampling technique for software defined radio

A novel under-sampling technique that has the same effect as using RF direct sampling is proposed. Simulation and an experiment to prove its validity have been carried out.     

Real-time spectrum sensing using software defined radio platforms

As the lack of frequency resources became a critical problem in recent years, solutions had to be found in order to use the available spectrum in a more efficient way. Cognitive radio (CR) technology is a possible answer to this, by proposing a dynamic spectrum access approach, which allows unlicensed users to access unused licensed frequency bands. In order to detect the presence of licensed users, any CR equipment has to perform a spectrum sensing process. This paper presents a practical solution for building this essential part of a frequency agile device. The implementation of the proposed real-time spectrum sensing solution is based on commercial software defined radio platforms. Hardware and software details regarding the described prototype are given, together with aspects related to the optimal configuration of the used platforms for such an application. Moreover, the performance that can be obtained using the proposed solution is evaluated through measurements performed in several different scenarios.     

Evolution and standardization of the smart antenna system for software defined radio

Transitioning proprietary or legacy software defined radio networks to open architectures, while often complicated, is increasingly critical to improve the interoperability and compatibility among SDR networks and the subsystems within those networks as well. With this in mind, two consortia, the SDR Forum and the Object Management Group, have teamed to define an open Smart Antenna specification. This specification defines a model (including an API) that simplifies the integration of an SA subsystem into a traditional SDR network. The specification is called the "Platform Independent Model (PIM) and Platform Specific Model (PSM) for the Smart Antenna" or "SA API specification." This article introduces the SA API, which provides a standard model and standard service of the SA system operating in SDR networks.     

一种软件无线电与认知引擎的接口实现方法

该文主要讨论在基于软件无线电的认知系统中,软件无线电平台和认知引擎的接口实现。文中提出了一种基于XML语言描述的接口实现方法,并简单举例说明了如何对软件无线电平台处理能力和认知引擎配置参数进行描述,进而又阐述了软件定义无线电平台与认知引擎间的信息传递方式。文章为在软件定义无线电台上构建认知无线电提供了一种简单,可行的实现方法,同时提高了认知无线通信系统的开放性。     

Submillimeter receivers for radio astronomy

The state of development of receivers for submillimeter-wave radio astronomy is reviewed. Bolometers for continuum observation, hot-electron mixer receivers for narrowband spectral line observation, and heterodyne receivers, both Schottky diode and superconducting tunnel junction, are presented. At the lower frequency end of the submillimeter band, standard waveguide techniques, scaled from millimeter wavelengths, prevail. At wavelengths shorter than about 0.5 mm, quasioptical designs are preferred. In the case of Schottky diode receivers, corner cube designs are used almost exclusively, whereas integrated mixer designs are the focal point of research for superconductor-insulator-superconductor (SIS) receivers at these wavelengths. Although such designs are extensively reviewed, it is nevertheless the Schottky diode mixer remains the element of choice at the shortest submillimeter wavelengths     

Roaming times of multi‐wireless systems for software defined radio

In this paper, we evaluate the roaming time performance for a reconfigurable multi‐mode mobile station (MS) that experiences possible transition from one kind of wireless system standard to another. In future software defined radio systems (SDR) (IEEE Commun Mag 2000; 138–143, IEE 1998; 1–6, IEEE 1999; 1212–1216, IEEE Commun Mag 1995; 33 ), reconfigurability of the MS is achieved by downloading the system configuration software code over the wireless channel. For evaluation of the roaming times, a generalized state diagram of the multi‐mode MS is presented. We focus on evaluating the times for sensing the universal pilot channel, classic base station pilot channel, association and connection establishment signaling are included. We investigate the effects of packet successful transmission probability over the wireless channel. We also consider the effects of the system resource blocking probability, MS resource blocking probability, and signaling bit rate over the universal base station channel for different cases and design scenarios. Such evaluations are important for prior design of SDR mobile terminal and universal base station in global roaming situations. We include some analysis results from many obtained. These show the feasibility of wireless software download, and switching between different wireless standard as the mobile station roams. Copyright © 2003 John Wiley & Sons, Ltd.     

The design and multiplier-less realization of software radio receivers with reduced system delay

This work studies the design and multiplier-less realization of a new software radio receiver (SRR) with reduced system delay. It employs low-delay finite-impulse response (FIR) and digital allpass filters to effectively reduce the system delay of the multistage decimators in SRRs. The optimal least-square and minimax designs of these low-delay FIR and allpass-based filters are formulated as a semi-definite programming (SDP) problem, which allows zero magnitude constraint at /spl omega/=/spl pi/ to be incorporated readily as additional linear matrix inequalities (LMIs). By implementing the sampling rate converter (SRC) using a variable digital filter (VDF) immediately after the integer decimators, the needs for an expensive programmable FIR filter in the traditional SRR is avoided. A new method for the optimal minimax design of this VDF-based SRC using SDP is also proposed and compared with traditional weight least squares method. Other implementation issues including the multiplier-less and digital signal processor (DSP) realizations of the SRR and the generation of the clock signal in the SRC are also studied. Design results show that the system delay and implementation complexities (especially in terms of high-speed variable multipliers) of the proposed architecture are considerably reduced as compared with conventional approaches.     

软件无线电标准符合性测试系统设计

随着软件无线电技术的迅速发展,越来越多厂家开展了基于软件无线电标准的技术研究和产品研制.由于各厂家对标准的理解不一致,研制软件产品的实现存在差异,导致未经符合性测试的软件之间不能相互兼容,需花费大量时间来进行波形移植开发和系统集成.针对该问题,提出了一种软件无线电系统标准符合性测试系统的实现方式,给出了系统测试内容、测...