A Novel M‐ary Code‐Selected Direct Sequence BPAM UWB Communication System

In this letter, a novel M‐ary code‐selected direct sequence (DS) ultra‐wideband (UWB) communication system is presented. Our purpose is to achieve a high data rate by an M‐ary code‐selected direct sequence bipolar pulse amplitude modulation (MCSDS‐BPAM) scheme. In this system, a particular DS code sequence is selected by the log₂M/2 bits from the DS gold code set. This scheme can accomplish both a high data rate without increasing the system bandwidth or changing the pulse shape and improve the BER with an increase of modulation level M even at a lower signal‐to‐noise ratio (SNR). The receiver signal processing algorithm is given for an MCSDS‐BPAM UWB system over an ideal AWGN channel and correlation receivers.     

基于光纤光栅的超宽带信号产生与传输

针对现有方法功率利用率低与调制实现困难的问题,采用基于光纤光栅（FBG）的超宽带（UWB）调制信号产生方法,建立了UWB信号产生系统。不仅可以实现UWB信号的调制,而且提高了产生信号的信噪比。实现了二进制相位调制（BPM）、脉冲幅度调制（PAM）和脉冲位置调制（PPM）等UWB信号产生。分析了光纤传输对产生信号的影响,...     

Combined Pulse Shape and Pulse Position Modulation for High Data Rate Transmissions in Ultra-Wideband Communications

In this paper we present a novel method for high data rate transmissions in ultra-wideband (UWB) communications systems. This is achieved through the combination of conventional pulse position modulation and pulse shape modulation schemes. The result is a pulse shape and position modulation that allows transmission of more bits of information in the same amount of time and using the same number of pulses as the conventional schemes. A feature of the proposed system is that the allowable alphabet is limited so as to ensure equal power in transmission of all symbols. Symbol size can also be easily changed without significantly changing the hardware of the system. Theoretical error performance analysis of this system is also provided.     

CAP-DPIM可见光混合调制方案

针对可见光通信系统传输性能问题,文章提出了一种无载波幅度相位(CAP)调制与数字脉冲间隔调制(DPIM)结合的混合调制方案。该方案分别利用两者频谱效率和功率效率较高的特点,发送端在脉冲间隔调制的脉冲时隙加载直流偏置光CAP(DCO-CAP)信号,实现混合调制信号的并行生成,接收端通过门限检测和最大似然检测完成混合调制信号的串行解调。推导了室内可见光高斯信道下混合调制方案的误码率(BER)及误帧率(FER)解析表达式。此外,从频谱效率和FER两方面对比分析了该混合调制方案与传统DPIM及DCO-CAP方案的性能优劣。数值仿真结果表明:当频谱效率相同时,混合调制方案较单一调制有更高的可靠性。     

A novel self-pilot-based transmit-receive architecture for multipath-impaired UWB systems

In the last few years, ultra-wideband (UWB) systems became an appealing technology for wireless communication applications. Unfortunately, when the transmission channel is affected by intersymbol interference (ISI), system performance of UWB systems equipped with receivers based on conventional matched filters presents error-floor phenomena. Aimed by these considerations, in this letter, we present a novel transmit-receive scheme allowing blind channel estimation and minimum mean-square error linear channel equalization. Essentially, the proposed scheme exploits a very short duration of the UWB pulse for achieving reliable blind deconvolution of the received signal. A nice feature of the resulting system is that blind deconvolution of the received signal is achieved without power and throughput losses. Simulation results support the effectiveness of the proposed scheme, and show that it is able to gain about 8 dB over current UWB receivers based on matched filtering on several test channels impaired by ISI.     

A novel multi-antenna impulse radio UWB transceiver for broadband high-throughput 4G WLANs

In the last years, a lot of attention has been devoted to both multi-antenna systems with space-time orthogonal block coding (STOBC) and ultra wideband (UWB) transceivers based on impulse-radio (IR) technologies. In this short contribution we anticipate the architecture of a novel transceiver merging both multi-antenna and pulse position modulation (PPM) IR-UWB techniques and then we test the performance in flat-faded application scenarios typical of emerging broadband 4G WLANs. Three main appealing features are retained by the sketched transceiver scheme. First, it allows to equip the UWB receiver with reliable estimates of the (possibly time-varying) underlying multiple-input multiple-output (MIMO) UWB without reducing the overall information throughput conveyed by the system. Second, the performance confirms that the proposed transceiver is able to achieve "full diversity" even at SNRs as low as 1.5-2 dB. As a consequence, the resulting BERs outperform those of current Single-Input Single-Output (SISO) IR-UWB transceivers over two orders of magnitude even at SNR's as low as 3-4 dB. Third, at target BER's below 10/sup -2/ and radiated powers around 250 /spl mu/W, the coverage ranges allowed by the proposed MIMO IR-UWB scheme typically outperform those of conventional SISO IR-UWB ones of about two orders of magnitude.     

一种新的基于磁感应技术无线地下传感网收发器设计

针对无线地下传感器网络（Wireless Underground Sensor Network,WUSN）中的信道高路径损耗、信道条件动态变化大和天线尺寸过大等问题,提出一种基于磁感应技术的WUSN收发节点的硬件设计方案。设计了通信系统节点的硬件结构及主控制器和线圈的选型,以及包括天线发射电路、接收电路、程控放大电路和高速A/D采样电路的收发器外围电路,并给出了相关关键参数设计性能指标,搭建了收发通信和性能测试平台。实验结果表明：经FIR滤波器和希尔伯特检波后低频干扰被滤除,降低了误包率,硬件节点满足要求,验证了设计的可行性和可靠性。     

Non‐Data‐Aided Weighted Non‐Coherent Receiver for IR‐UWB PPM Signals

This letter proposes an energy‐detection‐based non‐data‐aided weighted non‐coherent receiver (NDA‐WNCR) scheme for impulse radio ultra‐wideband (IR‐UWB) pulse‐position modulated signals. Compared to the conventional WNCR, the optimal weights of the proposed NDA‐WNCR are tremendously simplified as the maximum eigenvector of the IR‐UWB signal energy sample autocorrelation matrix. The NDA‐WNCR serves to blindly obtain the optimal weights and entirely circumvent the transmission of training symbols or channel estimation in practice. Analysis and simulation results verify that the bit error rate (BER) performance of the NDA‐WNCR closely approaches the ideal BER of the conventional WNCRs.     

M‐ary Bi‐orthogonal Modulation UWB with Narrowband Interference Suppression Capability

An M‐ary bi‐orthogonal modulation scheme for ultra‐wideband (UWB) systems capable of narrowband interference (NBI) suppression is proposed in this letter. We utilize a set of bi‐orthogonal pulse series to achieve NBI suppression. Through analysis and simulation, we verify that the proposed scheme can suppress NBIs effectively.     

Pulse Position Amplitude Modulation for Time-Hopping Multiple-Access UWB Communications

In this letter, we propose a new modulation scheme called pulse position amplitude modulation (PPAM) for ultra-wideband (UWB) communication systems. PPAM combines pulse position modulation and pulse amplitude modulation to provide good system performance and low computational complexity. The channel capacity of PPAM is determined for a time-hopping multiple-access UWB communication system. The error probability and performance bounds are derived for a multiuser environment.     

A low‐complexity MSK‐based M‐ary cyclic‐shift keying transceiver for direct sequence spread spectrum system over multipath fading channels

In this paper, a low‐complexity spread spectrum system with M‐ary cyclic‐shift keying (MCSK) symbol spreading is proposed. In addition, by using the minimum‐shift‐keying (MSK) as the chip‐level modulation, we obtain a high‐rate QPSK‐MCSK transceiver scheme which not only provides a constant‐envelop and continuous‐phase transmitted signal, but can also achieve a better performance than the conventional direct sequence spread spectrum (DSSS) system. At the transmitter, the data stream is first mapped into QPSK‐MCSK symbols in terms of orthogonal Gold code sequences, then followed by the cyclic prefix (CP) insertion for combating the interblock interference, and finally applying the MSK scheme to maintain the constant‐envelope property. The receiver first performs MSK demodulation, then CP removal, and finally the channel‐included MCSK despreading and symbol demapping. Furthermore, the single input single output (SISO) QPSK‐MCSK transceiver can be easily extended to the multiple input single output (MISO) case by incorporating the space–time block coding for high‐link quality. Simulation results show that the proposed SISO and MISO QPSK‐MCSK systems significantly outperform the conventional DSSS counterparts under the AWGN channel, and attain a more robust performance under the multipath fading channel. Copyright © 2011 John Wiley & Sons, Ltd.     

超宽带系统的脉位调制技术研究

超宽带是一种与传统无线通信技术有所区别的通信,针对影响超宽带脉位调制技术的因素进行了研究,简要介绍了超宽带的技术特征、调制解调原理和技术优点,重点分析了无载波的TH-PPM信号调制与解调的原理,最后通过理论研究,结合脉位调制的matlab仿真实验,得出跳时码周期对脉位调制的影响。     

Performance analysis of a rate adaptive multi-band ultra-wideband system based on quadrature fractal modulation scheme

1 Introduction Wornell and Oppenheim[1,2] first proposed a modulation technique as an interesting potential application of dy-homogeneous signals. Due to the fractal properties of the homogeneous signals, this technique is called fractal modulation afterwards. This class of homogeneous signals remains invariant under scaling of the time axis. Dy-homogeneous signals satisfy the dyadic self-similarity property[3] s (t ) = 2 kH s (2 kt) (1) For all integers k and a constant H, termed the degree…     

Adaptive coding and modulation scheme for satellite‐UMTS TDD systems based on a photogrammetric channel estimation method

The conventional wireless communication systems are designed to overcome the worst‐case channel, using the huge amount of redundant bits to assure communications performance and quality of services. Those systems cannot achieve the optimum spectrum and power efficiency. This paper presents an adaptive coding and modulation scheme used in the user terminals of the third‐generation satellite communication system. A three‐state photogrammetric channel estimation method is introduced for tracing the variations of large‐scale environments. The mobile user terminal dynamically switches the suitable coding and modulation schemes according to the result of photogrammetric channel estimator in order to maximize the power efficiency and data throughput. The real measurement data were used to validate our proposed method. The results show that the proposed method not only reduces the system complexity, but also mitigates the power control requirements and increases the data throughput for the land mobile satellite personal communication systems. Copyright © 2006 John Wiley & Sons, Ltd.     

On the UWB system coexistence with GSM900, UMTS/WCDMA, and GPS

This paper evaluates the level of interference caused by different ultra-wideband (UWB) signals to other various radio systems, as well as the performance degradation of UWB systems in the presence of narrowband interference and pulsed jamming. The in-band interference caused by a selection of UWB signals is calculated at GSM900, UMTS/wideband code-division multiple-access (WCDMA), and Global Position System (GPS) frequency bands as a function of the UWB pulsewidth. Several short-pulse waveforms, based on the Gaussian pulse, can be used to generate UWB transmission. The two UWB system concepts studied here are time hopping and direct sequence spread spectrum. Baseband binary pulse amplitude modulation is used as the data modulation scheme. Proper selection of pulse waveform and pulsewidth allows one to avoid some rejected frequency bands up to a certain limit. However, the pulse shape is also intertwined with the data rate demands. If short-pulses are used in UWB communication the high-pass filtered waveforms are preferred according to the results. The use of long pulses, however, favors the generic Gaussian waveform instead. An UWB system suffers most from narrowband systems if the narrowband interference and the nominal center frequency of the UWB signal overlap. This is proved by bit-error rate simulations in an additive white Gaussian noise (AWGN) channel with interference at global system for mobile communication (GSM) and UMTS/WCDMA frequencies.     

基于一阶统计量信道盲估计空时分集TH-PPM UWB系统

首先利用一种空时分集结构提出一种多入多出超宽带系统收发信机模型,并给出相应的信号检测方法.然后,利用脉位调制信号结构导致的接收信号一阶统计量循环平稳特性,提出一种适用于系统且没有估计模糊度问题的低复杂度盲信道估计方法.仿真结果表明,提出的盲信道估计方法由于复杂度低且没有估计模糊度,给接收机的信号检测提供了准确的信道状态...     

Superimposed Pilot Aided Multiuser Channel Estimation for MIMO‐OFDM Uplinks

This letter addresses the superimposed pilot aided multiuser channel estimation for the uplinks of multi‐input multi‐output orthogonal frequency‐division multiplexing systems. To mitigate the embedded‐data effects on the performance of channel estimation, a novel combining algorithm is proposed. Optimal pilot symbols are developed with respect to the least square channel estimate's mean square error. The averaged sum‐capacity lower bound is derived and simulated. Simulation results show that on a low signal‐to‐noise ratio regime, our proposed scheme achieves better performance and higher capacity than the conventional pilot aided approach.     

Performance of transmitted reference pulse cluster ultra‐wideband systems with forward error correction

Recently, an improved transmitted reference (TR) signaling scheme, referred to as transmitted reference pulse cluster (TRPC), was proposed for low‐rate ultra‐wideband (UWB) communications. Compared with conventional TR, TRPC has a more compact and uniform spacing for the reference and data pulses and therefore addresses the implementation problems posed by the long delay line requirement, as well as provides better bit error rate (BER) performance. In this paper, a TRPC‐UWB system, which includes practical forward error correction (FEC) coding such as that specified in the IEEE 802.15.4a standard, as well as more powerful convolutional codes, is developed. A performance analysis, which highlights the importance of selecting appropriate FEC codes, is presented. Results show that with a suitable FEC code, the TRPC‐UWB system is a promising candidate for low‐rate wireless personal area networks. Copyright © 2012 John Wiley & Sons, Ltd.     

满足FCC辐射掩模的UWB信号设计算法及性能分析

脉冲波形设计是超宽带无线通信技术研究中的重要内容。以满足联邦通信委员会(FCC)辐射掩模为前提,采用两次迭代的算法逐步对脉冲波形参数进行优化,设计了一种低复杂度、能够最大限度提高UWB系统的辐射功率的UWB信号。同时,研究了经过加性高斯白噪声(AWGN)信道,在跳时扩频脉位调制(TH-PPM)UWB系统中使用该窄脉冲的系统性能。仿真结果表明,该UWB通信系统比通常使用Manchester窄脉冲或Scholtz窄脉冲的UWB系统误码性能更优。这对于UWB系统的实际运用有很好的指导意义。     

基于空间分集的TH-UWB系统性能分析

为了提高UWB系统在低信噪比下的性能,利用IEEE 802.15.3a工作组建议的标准UWB室内信道模型,采用多个接收天线分析了二进制TH-PPM超宽带系统性能的改善。在理想功率控制下,分别采用不同数目的接收天线和不同SRake接收机选择路径数,对2PPM-TH-UWB系统性能进行了分析和仿真。仿真结果表明,随着天线数和选择路径数的增加,系统性能均明显提高,并且空间分集比路径分集对系统性能有更好的改善。