Low Complexity Digital Pre-Distortion (DPD) for Multi-Band Radio over Fiber Transmission Systems

Nonlinear distortion is one of key limiting factors in radio over fiber (RoF) transmission systems. To suppress the nonlinear distortion, digital pre-distortion (DPD) has been investigated considerably. However, for multi-band signals, DPD becomes very complex, which limits the applications. To reduce the complexity, many simplified DPDs have been proposed. In this work, a new multidimensional DPD is proposed, in which in-band and out-of-band distortion are separated and the out-of-band distortion is evaluated by sum and differences of all input signals instead of all individual input signals, thus complexity is reduced. An up to 6-band 64-QAM orthogonal frequency division multiplexing (OFDM) signal with each bandwidth of 200 MHz in simulations and a 5-band 20 MHz 64-QAM OFDM signal in experiments are used to validate the pro-posed DPD. The validation is illustrated in the means of power spectrum, AM/AM and AM/PM distortion, and error vector magnitude (EVM) of the received signal constellations. The average EVM improvement by simulation for 3-band, 4-band, 5-band and 6-band signals is 19.97 dB, 18.65 dB, 16.64 dB and 15.44 dB, respectively. The average EVM improvement by experiments for 5-band signals is 8.1 dB. Considering the ten times of bandwidth difference, experiments and simulation agree well.

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.

Robust Digital Non-Linear Self-Interference Cancellation in Full Duplex Radios with Maximum Correntropy Criterion

Full duplex radio increases the frequency efficiency but its performance is limited by the self-interference （SI）. We first analyze the multiple noises in the full duplex radio system and model such noises as an α - stable distribution. Then we formulate a novel non-Gaussian SI problem. Under the maximum correntropy criterion （MCC）, a robust digital non-linear self-interference cancellation algorithm is proposed for the SI channel estimation. A gradient descent based algorithm is derived to search the optimal solution. Simulation results show that the proposed algorithm can achieve a smaller estimation error and a higher pseudo signal to interference plus noise ratio （PSINR） than the well-known least mean square （LMS） algorithm and least square （LS） algorithm.

DIFFERENTIAL AMPLITUDE PHASE SHIFT KEYING: A NEW MODULATION METHOD FOR TURBO CODE IN DIGITAL RADIO BROADCASTING

The multilevel modulation techniques nf M-Differential Amplitude Phase Shift Keying (DAPSK) have been proposed in combination with Turbo code scheme for digital radio broadcasting bands below 30 MHz radio channel. Comparison of this modulation method with channel coding in an Additive White Gaussian Noise (AWGN) and multi-path fading channels has been presented. The analysis provides an iterative decoding of the Turbo code.

PERFORMANCE IMPROVEMENT FOR A WCDMA RADIO OVER FIBER SYSTEM USING DIGITAL PRE-DISTORTER

In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are applied in the ROF link so as to suppress the out-of-band spurious spectrum and improve the transmission performance.The experimental results show that the out-of-band emission due to existence of the third-order Inter-Modulation Distortion (IMD3) is obviously sup-pressed by these two DPD.An Adjacent Channel Power Ratio (ACPR) improvement of 8 dB is ob-tained for a single-carrier WCDMA signal transmission.These two DPD have equal ability in lin-earization of the ROF system for a three-carrier WCDMA signal transmission.There is no apparent memory effects exist in the ROF link.

PERFORMANCE EVALUATION OF LOW DENSITY PARITY CHECK CODES FOR DIGITAL RADIO MONDIALE (DRM) SYSTEM

In Digital Radio Mondiale （DRM） system, achieving good audio quality becomes a challenge due to its limited band-width of 9 or 10kHz and the very bad lading channels. Therefore, DRM needs highly efficient channel coding schemes. This paper, proposes the schemes which use the Low-Density Parity-Check （LDPC） coded Bit-Interleaved Coded Modulation （BICM） schemes for the implementation of DRM systems. Simulation results show that the proposed system is more efficient than the Rate Compatible Punctured Convolutional （RCPC） coded DRM system on various broadcast channels, and may be recommended as a coding technology for Digital Amplitude Modulation Broadcasting （DAMB） systems of China.

Digital Radio Broadcasting for Community Radios Using Pseudo-random Codes

This paper aims to present a digital radio broadcasting system that explores the advantages of pseudo-random codes. In this context, a transmitter and its dual receiver are able to reuse frequency spectrum bands without interfering on other existing communication systems. It is proposed a communication system that allows radio broadcasting with the following characteristics: lower transmission power, new communication channels and digital signal processing techinques to add positioning services in two dimensions.

Modulation for Digital Radio Broadcasting Using Amplitude Autocorrelation of Pseudo Random Noise Codes to Carry Information

The frequency bands used in mobile communications are allocated according to the type of application. With the need for more channels, the frequency spectrum has become a scarce natural resource. This study shows the results of a proposed modulation using a variation of the autocorrelation of pseudo-random codes to carry information. The work also presents the generation of multiple orthogonal axes to increase the bit rate thus improving the channel efficiency.

Digital broadcast channel estimation with compressive sensing

In order to reduce the pilot number and improve spectral efficiency, recently emerged compressive sensing （CS） is applied to the digital broadcast channel estimation. According to the six channel profiles of the European Telecommunication Standards Institute（ETSI） digital radio mondiale （DRM） standard, the subspace pursuit （SP） algorithm is employed for delay spread and attenuation estimation of each path in the case where the channel profile is identified and the multipath number is known. The stop condition for SP is that the sparsity of the estimation equals the multipath number. For the case where the multipath number is unknown, the orthogonal matching pursuit （OMP） algorithm is employed for channel estimation, while the stop condition is that the estimation achieves the noise variance. Simulation results show that with the same number of pilots, CS algorithms outperform the traditional cubic-spline-interpolation-based least squares （LS） channel estimation. SP is also demonstrated to be better than OMP when the multipath number is known as a priori.

Digital finance and renewable energy consumption:evidence from China

While digital finance and renewable energy consumption(REC)are two timely issues,it remains unclear whether the former affects the latter,especially in developing economies.This paper examines the impact of digital finance on China’s REC between 2011 and 2018 and explores the underlying mechanisms.Results show that digital finance,along with its coverage breadth and usage depth,significantly improved REC in China and that digital finance in the area of credit has had the most significant impact.Additionally,the results show that loan scale and income level are the main mediation variables,through which digital finance affects REC.The findings also suggest that economic growth and technological progress have increased REC in China,while carbon dioxide emissions have had no meaningful effect on this consumption.The results further indicate that policymakers must pay close attention to the role of digital finance when formulating policies on REC.To promote REC and environmental sustainability,developing economies like China should strengthen the breadth and depth of digital finance development,focus on the influence channels of digital finance,and promote economic growth and technological progress.

Digital Dividend： The Path Towards Business and Marketing Development

Wireless radio spectrum is an important resource that allows for increased business development, throtigh the provision of services using wireless networking infrastructures. Since radio spectrum is limited, an optimal utilization of it is required, by adopting advanced spectrum management methods. The current transition from analogue to digital terrestrial television may act as a unique opportunity, in order to reallocate this valuable spectrum resource. After the transition, a part of the traditional analogue television spectrum bands will be completely released, allowing for the use of this spectrum by sophisticated wireless systems. Furthermore, digital terrestrial television interleaves spectrum bands in order to avoid possible interference between adjacent channels used by broadcasting stations, thus leaving spectrum holes exploited by novel wireless networks, namely unlicensed secondary systems. In this context, this article investigates business and marketing development issues, arising by utilizing released and interleaved television spectrum bands

Research on Software Radio Fuze

The functions and characteristics of software radio are discussed. Using techniques and method of software radio, the concept and advantages of a new kind of radio fuze, software radio fuze, are analysed. Several kinds of hardware platform structures of the software radio fuze are studied and the key techniques are analysed. The software radio fuze will become the most promising radio fuze techniques in 21st century.

HD Radio发射与接收系统

在世界范围内,主流的数字声音广播除了DAB和DRM外,近年来HD Radio技术在美国得到了快速发展,其他一些国家和地区也正在进行试验,做应用的准备。HD Radio技术是用在AM和FM中的IBOC(带内同频道)技术的发展与完善,尤其是应用在FM波段的FM HD Radio技术系统,可实现模拟与数字节目同播,可使模拟FM广播平滑过渡到数字广播,设备改造投资少。首先介绍了HD Radio技术的发展现状,着重阐述了发射与接收技术系统的构成与工作原理。

数字身份识别的安全型病历车的研制与应用

目的 探讨针对解决病历存放安全性和病历车使用规范化问题的实用新型专利“一种基于RFID技术的安全型病历车”在临床中的应用。方法 于2024年1月至5月在浙江省嘉兴市第二医院康复科3个病区、ICU病房、外科病房使用该射频识别(RFID)技术的安全型病历车。比较使用前(2023年12月以前)及使用后(2024年1月至5月)的满意度情况。结果 与使用前比较,使用后各科室的使用满意率、安全满意率、与科室沟通满意率均高于使用前(P<0.05)。结论 使用RFID技术的安全型病历车能提高纸质病历管理质量及安全性,完善病房5S管理,显著提高各方面的满意率。

创新的中国数字调频广播技术方案——CDRadio与HD Radio的简介与比较

数字化正对中国广播电视行业产生着深刻的影响,传统的FM音频广播也面临着数字化改造。在DAB,HD Radio,DRM及CDRadio几种先进数字音频广播技术方案中重点比较了HD Radio与CDRadio。中国数字调频广播技术方案CDRadio实现了真正的带内数模混叠同播,并通过使用非规则频谱分配、LDPC纠错编码、时间分片等关键技术,获得了更好的性能增益。CDRadio技术方案创造性地在200 K模拟带宽内同时播出数字信号和模拟信号,使得现有调频电台无需做任何的频率规划更改就可以升级到数字调频广播,同时还能保持原有模拟调频节目播出,因此它是最适合中国国情的方案。

基于GNU Radio&USRP的IEEE802.15.4/6双协议收发系统

随着无线传感网络技术的不断发展,面向不同应用场景的单协议通信系统已满足不了各种应用场景的需求,如远距离或者高速率等。充分利用IEEE802.15.4标准的远距离和IEEE802.15.6标准的高速率特征,采用GNU Radio+USRP软件无线电平台来实现双协议互补无线通信功能,主要工作包括两种协议的媒体访问控制层和物理层的帧结构和数据编解码、前向纠错、误帧检测、帧同步与调制解调等部分的解析与功能实现。在此基础上进行了基于GNU Radio+USRP平台下双协议通信功能的验证,证明了该系统的可行性。

Joint power control and relay selection scheme for cognitive two-way relay networks

A joint power control and relay selection scheme is considered for a cooperative and cognitive radio system where a secondary network shares spectrum with the primary network. In the secondary network, two secondary users （SUs） communicate with each other via an assist relay. The main point is to provide the best system performance to SUs while maintaining the interference power at primary user （PU） under a certain level. Using convex optimization, a closed-form solution is obtained when optimizing the power allocation among the two nodes and relay. Based on this result, a joint power control and relay selection scheme with fewer variable dimensions is proposed to maximize the achievable rate of the secondary system. Simulation results demonstrate that the sum rate of the cognitive two-way relay network increases compared with a random relay selection and fixed power allocation.

Distributed Relay Beamforming in Cognitive Two-Way Networks: SINR Balancing Approach

In this paper, we study the problem of distributed relay beamforming for a bidirectional cognitive relay network which consists of two secondary transceivers and K cognitive relay nodes and a primary network with a transmitter and receiver, using underlay model. For effective use of spectrum, we propose a Multiple Access Broadcasting (MABC) two-way relaying scheme for cognitive networks. The two transceivers transmit their data towards the relays and then relays retransmit the processed form of signal towards the receiver. Our aim is to design the beamforming coefficients to maximize quality of service (QoS) for the secondary network while satisfying tolerable interference constraint for the primary network. We show that this approach yields a closed-form solution. Our simulation results show that the maximum achievable SINR improved while the tolerable interference temperature becomes not strict for primary receiver.

Study of Software Radio Receiver Development Platform

The Paper introduces an IF software radio receiver development Platform based on high-speed monolithic A/D Converter AD6640, Progranunable Digital Down-converter AD6620 and high-speed DSP chip TMSC320C6701. The implementation method is described as well as AD6620 parameter setting analysis. It also presents a flow chart of the on-line programming with the help of PC. The algorithm for demodulation AM signal is discussed.

The Community Radio in Thailand： 2012 Onwards

Radio broadcasting services in Thailand are in transition and face an uncertain future. This situation has arisen from enforcement of the 2010 Frequency Allocation and Telecommunications Business Act and the establishment of the National Broadcasting and Telecommunications Commission （NBTC） as a single, combined regulatory body for broadcasting and telecommunications. The Act brings in significant changes through ＂liberalization＂ in telecoms and broadcasting markets. Key events expected in the future, such as the implementation of AEC in 2015 and the transformation from analog to digital systems will have significant detrimental impact on the Thai broadcasting industry. These changes will affect 524 AM and FM radio stations and around 7,000 community radio operations. This paper gives a picture of radio broadcasting industry, especially of community radio stations, their history, present and future. It also argues that the survival of radio stations in Thailand after 2015 will depend on （l） its social, institutional, financial, and technical abilities; and （2） the ability of NBTC to adopt and enforce policy and regulation for promoting free and fair competition.