Design of BPS digital frontend for software defined radio receiver

In radio receivers,complete implementation of the software defined radio(SDR) concept is mainly limited by frontend.Based on bandpass sampling(BPS) theory,a flexible digital frontend(DFE) platform for SDR receiver is designed.In order to increase the processing speed,Gigabit Ethernet was applied in the platform at speed of 5×10~8 bit/s.By appropriate design of interpolant according to the position of input RF signals,multi-band receiving can be realized in the platform with suppression more than 35 d B without changing hardware.

Experimental approach for seeing through walls using Wi-Fi enabled software defined radio technology

Modern handheld target detection methods are typically restricted to line of sight （LOS） techniques. The design of a new method to detect moving targets through non-transparent surfaces could greatly aid the safety of hazardous military and government operations. In this paper, we develop through-wall virtual imaging using Wi-Fi enabled software defined radio to see moving objects and their relative locations. We use LabVIEW and NI Universal Software Radio Peripheral （NI USRP2921 radios with Ettus Research LP0965 directive antennas） devices to detect moving objects behind walls by sending and receiving a signal with respect to the USRP＇s location. Based on the signal-to-interference ratio of our signal （rather than the traditional signal-to-noise method）, we could determine the target object behind the wall. The two major applications for this project are： detecting an active shooter that is standing on the other side of the wall and detecting abnormalities in the human body such as breast cancer with more sensitive antennas. Likewise, firefighters, law enforcement officers, and military men would find more practical purposes for the use of this system in their fields. We evaluate the proposed model using experimental results.

Universal Band Pass Sampling Algorithm for Integration of Multiple Wireless Technologies Using Software Defined Radio Platform

Software Defined Radio (SDR) architecture allows us to integrate different mobile technologies using common hardware but with different software modules. To achieve this, we need to keep the signal in digital form for as much portion of the circuitry as possible, so that the implementation could be carried out by programmable digital processors. For this purpose, the incoming radio frequency (RF) signal is down converted to baseband spectrum using band pass sampling method. Research works carried out so far in this field have developed a few algorithms for band pass sampling. But, these algorithms are not much useful for most of the mobile communication systems and they use complex methodology for computing the sampling frequency values. In order to use the SDR platform to integrate all current wireless technologies, an efficient, cost effective and less complex algorithm that can be labelled as universal band pass sampling algorithm is developed in this paper for multiple mobile systems. This algorithm is based on a novel idea of inserting guard bands between the signals which reduces the design complexities of perfect ADC and sharp cut off filters. Using this algorithm, valid sampling frequency ranges and corresponding IF values are calculated for down converting RF signals. The algorithm is tested for six RF signals of different wireless technologies which are integrated and simultaneously down converted using SDR based front end receiver and thus the system multiplies the base station capacity by a factor of six. The simulation results are obtained and shown in this paper which proves that the algorithm developed works well for most of the wireless technologies.

A Software Defined Open Wi-Fi Platform

Wireless local area network(WLAN) is an indivisible part of the next generation wireless system. In this paper, an open Wi-Fi platform is designed and developed with special consideration of real-time signal processing. Such system can help accelerate research and development of future wireless network, especially in the case of cellular/Wi-Fi co-existing networks. This platform is based on the Intel general-purpose processor and the universal software radio peripheral(USRP) radio front end. The design including the physical layer implementations is purely software and is optimized for real-time signal processing on the general purpose processor. In the lab experiment, this platform supports baseband rate up to 700 Mbps with 2 transmitters in 80 MHz bandwidth. A cellular-Wi-Fi signaling interface between the Wi-Fi access point(AP) and the 5G core network is also developed and validated as an example for wireless resource allocation.

Software Radio: A Review of Design Considerations and Digital Hardware Choices

This paper reviews the requirements for Software Defi ned Radio (SDR) systems for high-speed wireless applications and compares how well the different technology choices available-from ASICs, FPGAs to digital signal processors (DSPs) and general purpose processors (GPPs) - meet them.

5G New Radio Prototype Implementation Based on SDR

The fifth generation (5G) New Radio (NR) has been developed to provide significant improvements in scalability, flexibility, and efficiency in terms of power usage and spectrum as well. To meet the 5G vision, service and performance requirements, various candidate technologies have been proposed in 5G new radio;some are extensions of 4G and, some are developed explicitly for 5G. These candidate technologies include non-Orthogonal Multiple Access (NOMA), and Low Density Parity Check (LDPC) channel coding. In addition, deploying software defined radio (SDR) instead of traditional hardware modules. In this paper we build an open source SDR-based platform to realize the transceiver of the physical downlink shared channel (PDSCH) of 5G NR according to Third Generation Partnership Project (3GPP) standard. We provide a prototype for pairing between two 5G users using NOMA technique. In addition, a suitable design for LDPC channel coding is performed. The intermediate stage of segmentation, rate matching and interleaving are also carried out in order to realize a standard NR frame. Finally, experiments are carried out in both simulation and real time scenario on the designed 5G NR for the purpose of system performance evaluation, and to demonstrate its potential in meeting future 5G mobile network challenges.

基于SDR的探测雷达反演树干分层介电参数仿真

为有效检测树干分层介质厚度和相对介电常数,该研究提出一种基于雷达探测的树干分层结构介电参数反演方法。基于斯涅耳定律结合树干生理结构特点,构建雷达信号在树干分层结构中的传播模型。利用软件定义无线电平台(software defined radio,SDR)搭建树干探测雷达。然后采用稀疏分解算法、K-SVD字典训练以及层剥离算法对探测雷达回波信号进行参数反演,并对不同的稀疏分解算法反演结果进行了对比。试验表明在回波混叠和无混叠的情况下,该方法均能够对树干分层介质厚度和相对介电常数进行估算;无混叠时相对介电常数和厚度的反演误差分别在2.93%和3.5%以内,混叠时相对介电常数和厚度的反演误差分别在7.52%和7.61%以内。综合试验结果表明,在5种反演算法中,SAMP算法在未知信号稀疏度的条件下表现最佳,具有较高的反演准确率和鲁棒性。

基于SDR的FPGA加速MIMO通信系统设计

重点研究基于软件定义无线电(Software Defined Radio,SDR)和现场可编程逻辑门阵列(Field Programmable Gate Array,FPGA)的多进多出(Multiple Input Multiple Output,MIMO)通信系统设计。利用SDR技术建立具有灵活性和可配置性的通信平台,以适应不同通信标准和应用场景。深入研究基于SDR的信号转换与处理方法,包括数字信号处理(Digital Signal Process,DSP)和MIMO信号处理算法。在此基础上,引入FPGA加速技术高效执行MIMO信号处理算法,提高系统的实时性和处理速度。最后,通过对比实验,验证所提出方法的性能优势。

Efficient Time Synchronization Approach for Wireless Communication Systems on GPP-Based Software-Defined Radio Platform

General purpose processer （GPP） based software-defined radio （SDR） platforms provide wireless communication system engineers with maximal architecture flexibility and versatility to construct a wideband wireless communication system. Nevertheless, the lack of hardware real-time timing control makes it difficult to achieve time synchronization between the base station and the terminals. In this paper, a software-based time synchronization （STS） method is proposed to realize the time synchronization of time division multiple access （TDMA） based wireless communication systems. A high precision software clock source is firstly constructed to measure the elapse of processing time. The Round-Trip Delay （RTD） algorithm is then presented to calculate timing advance values and achieve time synchronization. An example TDMA system is implemented on Microsoft Sora platforms to evaluate is effective to enable time synchronization for wideband the performance. Experiments show that the proposed mechanism wireless communication systems on GPP-based SDR platforms.

基于GNU Radio和USRP的宽频带并行感知平台设计

针对当前宽带频谱感知机制在感知精度和感知效率方面的不足,提出了一种基于滤波器组的宽频带并行感知方法,通过将多个相邻子带灵活组合实现非等带宽信道的频谱感知,对多个子带进行并行检测实现对宽带频谱的高效感知。同时,利用GNU Radio和USRP软件无线电构建了宽频带感知平台,验证了该感知方法的性能和有效性。实验结果表明,该感知平台能够在较低SNR和较少感知时间的情况下获得更高的感知性能,适用于非等带宽多信道频谱感知。

基于GNU Radio的230MHz多通道主站电台的设计

采用GNU Radio技术及与其配套的硬件前端USRP设计和实现了230 MHz软件无线电多通道主站电台。该主站电台在调制方式上与现有无线电台设备全面兼容,覆盖了整个电力系统230 MHz全双工频段,可以同时在多个频点以不同的速率和调制方式与不同制式的从站电台进行双工通信。所提出的方案可以充分利用230 MHz无线频率资源,增加终端接入数量,提高通信系统组网的灵活性和可靠性,同时有效降低维护和升级的成本。

A low power flexible PGA for software defined radio systems

This paper proposes a new low power structure to improve the trade-off between the bandwidth and the power consumption of a programmable gain amplifier（PGA）.The PGA consists of three-stage amplifiers, which includes a variable gain amplifier and DC offset cancellation circuits.The cutoff frequency of the DC offset cancellation circuits can be changed from 4 to 80 kHz.The chip was fabricated in 0.13μm CMOS technology. Measurement results showed that the gain of the PGA can be programmed from -5 to 60 dB.At the gain setting of 60 dB,the bandwidth can be tuned from 1 to 10 MHz,while the power consumption can be programmed from 850μA to 3.2 mA at a supply voltage of 1.2 V.Its in-band OIP3 result is at 14 dBm.

A 4th-order reconfigurable analog baseband filter for software-defined radio applications

This paper presents a 4th-order reconfigurable analog baseband filter for software-defined radios.The design exploits an active-RC low pass filter（LPF） structure with digital assistant,which is flexible for tunability of filter characteristics,such as cut-off frequency,selectivity,type,noise,gain and power.A novel reconfigurable operational amplifier is proposed to realize the optimization of noise and scalability of power dissipation.The chip was fabricated in an SMIC 0.13μm CMOS process.The main filter and frequency calibration circuit occupy 1.8×0.8 mm;and 0.48×0.25 mm;areas,respectively.The measurement results indicate that the filter provides Butterworth and Chebyshev responses with a wide frequency tuning range from 280 kHz to 15 MHz and a gain range from 0 to 18 dB.An IIP3 of 29 dBm is achieved under a 1.2 V power supply.The input inferred noise density varies from 41 to 133 nV/（Hz）;according to a given standard,and the power consumptions are 5.46 mW for low band（from 280 kHz to 3 MHz） and 8.74 mW for high band（from 3 to 15 MHz） mode.

基于GNURadio的频谱分析仪设计

设计了一种基于软件无线电(SDR)平台GNURadio便携式频谱分析仪,给出了完整的设计方案。频谱分析仪由天线、收发转换开关、射频前端、中频接收、ADC、混频器、抽取滤波、DSP、移动客户端显示、云端存储组成,采用HackRF One作为信号处理模块的射频中频硬件平台。该分析仪具有频率分辨率可调、频带宽、便携性好、灵活性强等特点,可广泛用于实验教学。

面向SDR应用的多核DSP低功耗设计

多核DSP已成为软件无线电技术(SDR)的重要组成部分,主要负责通信系统中的基带数字信号处理。通信系统对于功耗有严格要求,使得面向软件无线电应用的多核DSP低功耗研究变得越来越重要。根据基带数字信号的处理特点,设计了基于数据和任务驱动门控时钟的特殊指令及相关硬件功能部件。多核DSP通过执行特殊指令调用时钟控制单元,适时开启和关闭DSP核,从而降低多核DSP的功耗。针对目标多核DSP的实验表明,采用该设计方法能有效地降低多核DSP的平均功耗。

基于SDR的快跳频通信系统方案及实验

为解决现有快跳频通信系统依赖卫星授时的问题,提出一种基于软件定义无线电(SDR)的快跳频方案。首先,采用真随机序列对调制信号执行跳频运算,并通过信道下变频、低通滤波和幅度峰值检测运算获得跳频表;其次,根据解跳后基带信号正交解调幅度峰峰值分布特性搜索精确起跳点;最后,对信号执行下变频并检查正交解调幅度峰峰值是否超过阈值,从而实现解跳。实验使用两台通用SDR设备,按照每个符号周期4跳的跳速,在有其他连续信号的实际信道中进行通信实验,验证了所提方案的有效性和适应性。

基于GNU Radio的ADS-B信号收发系统设计

针对高集成度ADS-B系统不易开展创新性研究的问题,基于软件无线电设计了一套ADS-B信号收发系统;首先以可修改形式实现ADS-B报文编码、基带信号生成、前导脉冲检测、信号解调以及ADS-B信息解码等自定义GNU Radio模块的编写;然后创建ADS-B发射机和接收机流图,驱动硬件外设HackRF实现ADS-B信号的发射与接收;最后通过实验对各模块功能及数据接口进行测试;实验结果表明,该系统设计方案可行,ADS-B信号格式及报文广播速率符合Do-260B标准,且ADS-B接收机接收灵敏度为-68 dBm,信号检测率达89%。

SDR基站在网络升级改造中的应用

围绕SDR基站的特有技术特点、现有设备支持能力和部署中需注意的问题,针对运营商面临的网络发展环境和运营状况,提出了SDR基站的主要应用场景,并提出在市区、县城等场景中探索利用GL1800构建轻型态网络的思路。

信道均衡在PlutoSDR上的实现

针对软件无线电技术作为当今通信系统和通信技术的发展趋势,在一款便携的零中频软件无线电平台PlutoSDR上开展的信道均衡研究,使得将贴合实际的通信系统引入实验教学成为可能。以无线通信中的信道均衡为研究内容,基于PlutoSDR软件无线电平台完成了LMS均衡算法和MMA均衡算法的具体实现;在2台PlutoSDR搭建的无线通信收发系统中对2种均衡算法做了验证和性能分析,通过星座图直观体现了信道均衡对减小码间串扰的有效性,误差向量幅度和误码率减小进一步表明了信道均衡有效提高了系统的传输可靠性。将通信中的关键技术在PlutoSDR搭建的复杂通信系统中实现和应用,对于通信原理实验教学有重要意义。

基于Gnuradio与Hackrf的无线通信收发系统实现

随着无线通信技术的高速发展,需要对大量的信号及数据进行高效、快速、可操作性更高并且相对低成本的处理,这便对无线通信系统提出了更高的要求。Gnuradio是一种免费的开源软件无线电开发平台工具,在其图形化操作界面中集成了丰富的信号源与信号处理模块,通过功能强大的信号处理模块可以在PC端对无线通信中发送与接收端的信号进行编解码、调制与解调,时域和频域同步等处理。以Hackrf作为硬件平台,通过搭建GRC流图在射频段与PC端对信号及数据进行处理并发送与接收,实现了基于软件无线电平台的无线通信收发系统。