Full-duplex hybrid PON/RoF link with the 10 Gbit/s 16-QAM signal for alternative wired and 60 GHz millimeter-wave wireless accesses

A novel full-duplex hybrid access link with 10 Gbit/s 16-ary quadrature amplitude modulation (16-QAM) wired and wireless converged signal is proposed, which can provide PON access or RoF-based wireless access alternately with centralized lightwave source. The converged signal, consisting of the 10 Gbit/s 16-QAM baseband optical signal and two optical local oscillators (OLOs), is generated by central station and can be decomposed in different patterns at remote base station. For the wired PON access, the identical frequency OLO is used to coherently demodulate the 16-QAM signal; while for the RoF-based wireless access, the 16-QAM signal and its parallel polarized OLO are abstracted as optical millimeter wave by a polarization beam splitter; the other OLO is used as the uplink optical carrier to carry wired or wireless uplink signal. Since the three tones come from the same source, they maintain high coherency even after transmitted over fiber link. The proposed hybrid wired/wireless full-duplex fiber link suffers little from fiber chromatic dispersion. These are verified by simulations for both wired and wireless access applications.     

100 Gbit/s Nyquist-WDM PDM 16-QAM Transmission over 1200 km SMF-28 with Ultrahigh Spectrum Efficiency

Nyquist wavelength-division multiplexing (N-WDM) allows high spectral efficiency (SE) in long-haul transmission systems.Compared to polarization-division multiplexing quadrature phase-shift keying (PDM-QPSK),multilevel modulation,such as PDM 16 quadrature-amplitude modulation (16-QAM),is much more sensitive to intrachannel noise and interchannel linear crosstalk caused by N-WDM.We experimentally generate and transmit a 6 × 128 Gbit/s N-WDM PDM 16-QAM signal over 1200 km single-mode fiber (SMF)-28 with amplification provided by an erbium-doped fiber amplifier (EDFA) only.The net SE is 7.47 bit/s/Hz,which to the best of our knowledge is the highest SE for a signal with a bit rate beyond 100 Gbit/s using the PDM 16-QAM.Such SE was achieved by DSP pre-equalization of transmitter-side impairments and DSP post-equalization of channel and receiver-side impairments.Nyquist-band can be used in pre-equalization to enhance the tolerance of PDM 16-QAM to aggressive spectral shaping.The bit-error ratio (BER) for each of the 6 channels is smaller than the forward error correction (FEC) limit of 3.8 × 10-3 after 1200 km SMF-28 transmission.     

Optically Powered Remote Units for Radio-Over-Fiber Systems

Optically powered radio-over-fiber remote units have been designed and constructed for distributed antenna system applications using separate fibers for power and signal transmission. The feasibility of this approach has been investigated through a series of transmission measurements, based on the IEEE 802.11g wireless local area networking standard at a frequency of 2.5 GHz using 64-QAM OFDM modulation at 54 Mb/s. These measurements show that high-quality multilevel signal transmission is possible with modest levels of optical power at the central unit. For example, an EVM of around 3% has been achieved for an RF output power of 0 dBm using a central unit optical power of 250 mW over a link length of 300 m.      

Corona Based Optimal Node Deployment Distribution in Wireless Sensor Networks

This paper shows the trade off between different modulation techniques such as multi level quadrature amplitude modulation, multi level phase shift keying, and multi level differential phase shift keying for upgrading direct detection optical orthogonal frequency division multiplexing systems with possible transmission distance up to 15,000 km and total bit rate of 2.56 Tb/s. The 2.56 Tb/s signal is generated by multiplexing 64 OFDM signals with 40 Gb/s for each OFDM. Variations of optical signal to noise ratio (OSNR), signal to noise ratio (SNR), and bit error rate (BER) are studied with the variations of transmission distance. Maximum radio frequency power spectrum, and output electrical power after decoder are measured for different multi level modulation techniques with carrier frequency. It is observed that multi level QAM has presented better performance than multi level PSK and finally multi level DPSK in optical OFDM systems. Maximum output power after decoder is enhanced with both 32-PSK, and 64-QAM. Quadrature signal amplitude level at encoder is upgraded with 64-QAM. It is noticed that OSNR, SNR, and BER are improved using 4-QAM OFDM system than either QPSK or 4-DPSK.     

Millimetre-wave electro-optical upconverter for wireless digitalcommunications

A millimetre-wave optical upconverter using a semiconductor laser diode and high-speed external optical modulator is described. Upconversion and transmission of 16-QAM and 64-QAM digital subcarriers over a 38 GHz optical fibre-wireless link are demonstrated     

Fiber-optic transmissions of microwave 8-phase-PSK and 16-aryquadrature-amplitude-modulated signals at the 1.3-μm wavelengthregion

Transmissions of a 6-GHz 8-phase phase-shift-keyed (8φ-PSK) signal over a 12.5-km single-mode fiber with a 5-dB power margin and bit-error-rate (BER) of 10^-10 and a 6-GHz 16-ary quadrature-amplitude-modulated (QAM) signal over the same distance with a 2-dB power margin and BER of 10^-12 were demonstrated. The 8φ-PSK digital modem operated at 78Mb/s and the 16-QAM digital modem operated at 90 Mb/s. A high-speed multimode InGaAsP laser diode and a high-speed p-i-n diode were used in both fiber-optic transmission systems. Floor characteristics and power penalties observed in the BER performances of both systems were found to be caused by the intensity noise of the laser diode, particularly the reflection-induced intensity noise     

Millimeter-wave broad-band fiber-wireless system incorporating baseband data transmission over fiber and remote LO delivery

We present the first demonstration of a millimeter-wave (mm-wave) broadband fiber-wireless system which incorporates baseband data transmission in both the downstream (622 Mb/s) and upstream (155 Mb/s) directions. The local oscillator (LO) required at the remote antenna base station for up- and downconversion to/from the mm-wave radio frequency (RF) is delivered remotely via a modulation scheme that is tolerant to the effects of fiber chromatic dispersion on the detected LO carrier power. The technique employs a single dual electrode modulator located at the central office (CO) and the data and an RF signal at a frequency equal to half the LO frequency, are applied simultaneously to the device. The modulation scheme was optimized as a function of the modulator operating conditions. Simultaneous bidirectional radio transmission in the mm-wave fiber-wireless network was implemented using specially designed mm-wave diplexers located at the base station (BS) and customer unit, and a single Ka-band printed antenna array at the BS operating simultaneously in transmit and receive mode. Error-free data transmission was demonstrated for both down(34.8 GHz) and uplinks (37.5 GHz) after 20 km of single-mode optical fiber and a bit error rate (BER) of 10/sup -6/ was achieved after the inclusion of a 2-m radio link.     

16-QAM相干光纤通信系统星座图的优化与选择

基于16-QAM的相干光纤通信系统其抗噪声能力与调制格式的星座图特征密切相关。文章分析了Star 16-QAM的星座图在各种圈比下受噪声影响的特性,通过数值计算获得了在不同噪声条件下星座图的最佳圈比。研究了Square和Star两种16-QAM对激光相位噪声的要求,分析结果表明,获得相同的BER性能时,Star 16-QAM由激光相位噪声引起的光信噪比代价更小。     

光接入网络中的数字信号处理技术

采用先进的数字信号处理(DSP)技术,在发射机和接收机分别引入预处理和后处理,以提高光接入网络的频谱效率并延长传输距离。研究了一种基于光超奈奎斯特(Super-Nyquist)滤波的类9状态正交振幅调制(9QAM)信号多模均衡(MMEQ)后端DSP算法,使用这种方案,能够有效提高频谱效率,实现了频谱效率高达4 bps/Hz的正交移相键控(QPSK)信号传输;还研究了一种基于数字SuperNyquist信号前端预处理的方案,此方案的优点是不需要光预滤波即可达到相同的频谱效率。使用一个采用直接调制激光器(DML)、直接探测和数字均衡技术的高速无载波幅度相位-64状态正交振幅调制(CAP-64QAM)系统,在20 km标准单模光纤(SSMF)上实现了创纪录的60 Gbit/s CAP-64QAM信号传输;使用相干探测,实现了速率高达100 Gbit/s的64状态正交振幅调制-正交频分复用(16QAM-OFDM)实时传输系统,解决了实时OFDM信号处理中的关键问题。     

基于雷达组网远程监控系统设计与实现

针对雷达组网系统对远端雷达站监控的需要,提出了一种雷达远程监控系统设计方法。采用高性能TMS320DM642处理器作为系统硬件平台,应用其高速处理性能和片上集成外设端口功能,实现对雷达状态视频信号采集及数据压缩处理,利用其IP端口完成远程数据传输。该系统嵌入远端雷达站,以视频方式收集雷达工作状态信息并上传;雷达组网系统接收并显示各雷达视频信息,实现了远程监控。     

Comparison of coherent optical single-carrier and multi-carrier superchannel with FDM and FDE

Optical superchannel employing single-carrier (SC) and multi-carrier (MC) subband modulation techniques have been widely discussed for high-speed coherent optical transmission and networks. In this paper, we establish uniform system design based on frequency-domain equalization (FDE) and carry out a thorough study on orthogonal frequency division multiplexing (OFDM) superchannel versus SC frequency division multiplexing (SCFDM, also named as DFT-spread-OFDM) superchannel. The baseband signal characteristics of SCFDM and OFDM are analyzed. SCFDM and OFDM superchannel systems with 4-, 16-, 64- and 256-QAM formats and polarization division multiplexing (PDM) are numerically investigated against various impairments. The results show that SCFDM superchannel outperforms its MC counterpart against finite DAC&ADC resolution and fiber nonlinearities, while suffers more penalty when very large dispersion or laser phase noise exists.     

基于智能复合天馈线的室内覆盖系统故障处理维护策略研究

本文对目前移动通信中常用的天馈线模式和室内分布系统维护情况进行了分析,针对造成通信质量下降的重要因素：天馈线系统的维护问题进行探究,提出了基于智能复合天馈线远程供电传输模式下对室内分布系统的故障处理和维护方式,建立了新的故障监控和维护方式。在原有移动通信基站智能复合信号源和直流电源合路进天馈线远程传输供电系统的基础上通过增加室内分布天馈系统故障监测模块和功分器自动控制增益模块内置定向耦合器。并与天馈线驻波比或回损的值和隔离度及电压/电流标准数据库数学模型配合共同来实现室内分布系统天馈线的安装质量和网络运行情况的好坏判断。     

McBSP技术在数据传输中的应用

在嵌入式数据传输系统中经常会遇到DSP芯片与模/数转换器接口的问题,为提高信号的采样、传输速度与精度,增强系统可靠性,给出了基于DSP芯片的多通道缓冲串口(McBSP)在数据传输中作为接收器的原理、硬件与软件设计方法。选用TI公司的C5000系列定点DSP TMS320VC5502芯片与TI公司的10位高速串行逐次逼进型转换器模/数转换芯片TLV1572进行无缝连接,通过TLV1572对模拟数据进行采样,后经A/D转换为数字信号,DSP的McBSP串口进行接收,实现了不经任何转换的实时数据传输。该系统设计方案电路简单,可靠性好,易于实现,具有一定的通用性。     

Fiber optic microcellular radio

A distributed antenna system consisting of optical fiber connected canisters is proposed to replace or supplement the base station antennas required for cell splitting of growing cellular mobile radio systems. The end-to-end linear transmission of RF signal voltage can be maintained over the wide dynamic range of mobile radio. The technical feasibility of multiplexed subcarrier transmission using available lightwave components has been verified by signal-to-noise ratio and intermodulation distortion measurements. Measurements of a two-way audio link over both simulated and real radio paths have demonstrated the compatibility of a prototype lightwave transceiver, designed for the canister, with the existing base station and mobile equipment     

偏振复用QPSK相干光数字通信系统实验研究

建立了偏振复用正交相移键控(QPSK)传输及相干检测的数字通信实验系统,并分析系统的性能。40Gbit/s的偏振复用QPSK信号在单模光纤(SMF)中传输了100km;信号光与本振光在接收端进行混频并下变频,最后用数字信号处理(DSP)算法对接收信号离线处理。比较了光纤传输前后不同的光信噪比(OSNR)下的误码率(BER),实验结果表明,所使用的DSP算法能克服光纤信道对信号的主要损伤,对高速的相干检测信号进行有效的恢复。     

Transporting CDMA signals over an analog optical link

We have investigated transmitting wireless code division multiple-access (CDMA) signals from a remote antenna to a centralized base station over an analog optical link. We present specifications for transmission of standard (IS.95) CDMA signals and demonstrate that unisolated uncooled lasers can meet these requirements. Tests were conducted using both a 1.3-μm Fabry-Perot laser and a 1.55-μm distributed-feedback laser (DFB)     

Impact of noise and nonlinear distortion due to clipping on the BERperformance of a 64-QAM signal in hybrid AM-VSB/QAM optical fibertransmission system

Experimental BER measurements of a 64-QAM signal in a hybrid AM-VSB/QAM optical fiber transmission system are shown to be in good agreement with a corrected and reinterpreted theory of impulsive and Gaussian noise based on Middleton's class B impulsive noise model. Fiber dispersion induced distortion of the chirped laser output is also shown to adversely affect the QAM signal     

64-Gb/s highly reliable network switch (RHiNET-2/SW) using paralleloptical interconnection

RHiNET-2/SW is a network switch that enables high-performance optical network based parallel computing system in a distributed environment. The switch used in such a computing system must provide high-speed, low-latency packet switching with high reliability. Our switch allows high-speed 8-Gb/s/port optical data transmission over a distance of up to 100 m, and the aggregate throughput is 64 Gb/s. In RHiNET-2/SW, eight pairs of 800-Mb/s×12-channel optical interconnection modules and a one-chip CMOS ASIC switch LSI (a 784-pin BGA package) are mounted on a single compact board. To enable high-performance parallel computing, this switch must provide high-speed, highly reliable node-to-node data transmission. To evaluate the reliability of the switch, we measured the bit error rate (BER) and skew between the data channels. The BER of the signal transmission through one I/O port was better than 10^-11 at a data rate of 800 Mb/s ×10 b with a large timing-budget margin (870 ps) and skew of less than 140 ps. This shows that RHiNET-2/SW can provide high-throughput, highly reliable optical data transmission between the nodes of a network-based parallel computing system     

Channel Capacity Between Antenna Arrays— Part II: Amplifier Noise Dominates

In this paper (Part II of two), we continue examining the use of space-time coding techniques to achieve very-high spectral efficiencies in highly scattering environments, using multiple transmit and receive antennas. The goal is to increase as much as possible the number of antenna elements, which is particularly difficult at the remote station, which usually has a more limited space allotted to the antenna array than at the base station. Under the assumption that sky noise was the dominant noise source, Part I addressed the channel-capacity effects of mutual impedance between antenna elements in the remote array, and the correlation between the signal and noise fields received by these elements. In Part II, we consider the same effects under the assumption that amplifier noise is the dominant noise source. The question of how closely the receiving array elements can be spaced depends on how precisely the channel can be estimated. This is related to the high-precision requirement experienced with supergain antenna arrays. The supergain connection is made explicit by showing that the optimum channel capacity for the case of a single transmitting element is achieved by using the supergain weights for the receiving array. To indicate the effect of noisy channel estimation, the loss in receiver antenna gain due to noise in weight estimates is computed with a simple simulation model of scattered propagation for the single-transmitting-antenna element case     

光伏发电通信基站电源远程监测系统的设计

基于对处于偏远地区的光伏发电基站电源运行情况进行远程控制和检测的目的,设计了针对性的监测系统,基站电源发电的电压、电流值每5 s采集一次,通过GPRS模块无线高速传输到总站计算机进行检测和控制。进行串口通信实时数据采集、存储、查询,并完成对上位机串行口接收数据设置、上位机对下位机工作情况的检测和系统功能的设定。探讨了GPRS模块进行数据传输的过程,MC35i驱动及AT指令的编写和数据传输协议的制定。在实验的基础上,采集到日光强度改变时基站电源运行情况的数据,为提高太阳能电池的利用率提供了实践依据。