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中国矿业大学2009届本科生毕业设计（论文）第17页翻译部分英文原文Coal Face Wireless Sensor Network Physical Layer Design Based On UWB TechnologyAbstract In order to guarantee the safety of coal face production, it is necessary to monitor and surveillance face Shearer, scraper transport planes, hydraulic support, transport machines, broken machines etc . At present, it is difficult for the cable transmission mode to adapt to changes in the work site of the coal face. Transmission lines are often damaged and snapped for various factors, we use wireless sensor network (WSN), which is flexible to be placed and extensible, to resolve this problem. This paper discuss the design of the WSN transceiver for coal face with UWB technology. This kind of transceiver has some useful advantage such as low cost, low power consumption, simple structure, easy to implement the design of the hardware, no need to estimate the coal face Channel characteristics. However, detection efficiency is slightly lower, but the error rate can meet the requirement. 1. Introduction Coal face must face the complicated geological conditions and poor working conditions. In order to ensure the safety of production in the coal face, it is necessary to monitor real-time the face Shearer, scraper transport machine, hydraulic support, reprint machine, broken machines and other large equipments. In addition, we must monitor the ground pressure, gas, carbon monoxide, dust and other environmental parameters. At the same time, mobile voice and image communications is required. At present, the signal monitored and derived from the coal face is transmitted by cable. As the face is moving constantly and the going of the coal mining process, all kinds of large-scale iron and steel equipments in the coal face need to be boosted circularly and continually. The shape of the space is constantly changing with the change of the relative position of the equipments. Correspondingly, communication in cable is difficult to be applicable with the working scene changing, so transmission lines is damaged or snapped frequently ,and the coal face mobile voice and image communication is impossible .All these issues cause many latent trouble to the Safety of the production. We think wireless sensor network (WSN) is feasible to implement monitoring and surveillance to the coal face, for it has some useful characters of placing flexibly, expanding simply, moving easily and self-organization. 2. WSN architecture in the coal face The sensor network system structure of the mining Coal face is shown in Figure 1. In this Figure, the sensor nodes send the information of acquistion through one or more jumps to the cluster node, the base station (sink node) is responsible for the collection of data, and transmit them to task management node through up-slot network, task management Node is responsible for the integrated process the data and also issued instruction to sensor networks. The tunnel of coal face is a limited space. Bracket, shearer, transport and other large metal equipments are layout and coal, rocks and other media is a non-uniform restricted space, which all make the transmission channel more complex, fading and multi-path phenomena more serious in the transmission of wireless sensor nodes signal. These are different from sensor networks on the ground. Therefore, the design of transceiver node of it is particularly important. At present, there are three main technologies of the physical layer in wireless sensor networks: narrow-band modulation technology, spread spectrum technology and ultra-wideband (UWB) technology. While UWB technology possesses some attractive advantages such as low power spectrum density, low-complexity system, Low sensitivity to the channel fading, better security and so on. Considering the advantages and the characteristics of coal face naturally, we have adopted Impulse radio ultra-wide band (IR-UWB) technology, and the reasons are followed: 1) UWB technology consumes lower power and has lower power spectrum. Low power consumption, low-cost and small size are the most important feature of wireless sensor network nodes. Narrow-band modulation technology, spread spectrum modulation technology generally use sine carrier , IF and RF circuits exist in the systems, so consuming more power than the UWB technology with no carrier. Transmission medium in the coal face is non-uniform, which leading to more transmission loss than wireless communications systems on the ground. Therefore low power consumption becomes particularly important. In the coal face, as WSN node presents zonal distribution, nodes just need to communicate with neighbor-nodes. The WSN system based on UWB, consuming lower transmission power, can meet the requirements and avoid the interference with each other in the narrow-band communications node. Inaddition, thelow power consumption and high penetrating power help to design safe equipment and transmit disaster relief signal. 2) Strong anti-interference ability. In the coal face, electrical and mechanical equipment has narrow distribution. When equipment starts or stop, electrical sparkle may cause a lot of electromagnetic interference. So good anti-interference capability is strongly required in the wireless communication. 3) Good Anti-interference to multi-path ability. Coal face has some inherent characters, such as narrow space, more types of media, a multi-path intensive channel, while IR-UWB can be applied to this complicated environment with its advantages: narrow Pulse width, small pulse duration ratio, high multi-path resolution, strong anti-multi-path and fading Capacity. 4) Simple structure. The characters of IR-UWB, such as no modulation and up/down conversing frequency, simple transmitter structure, lower power consumption, make it more acceptable. According to the complexity of the node and power consumption into considerations, IR-UWB technology is very applicable to the design of the wireless sensor network physical layer. Therefore, compared to narrow-band modulation technology, spread spectrum technology, the wireless communication system based on the UWB technology present a good performance on the energy consumption, robustness, anti-multi-path and anti-noise, and so on. The modulation of IR-UWB are mainly PAM (OOK), PPM and BPM (Bi-Phase Modulation), but the presence of lines spectrum in PAM and PPM not only make ultra-wideband pulse signal difficult to meet a certain spectrum Requirements, but also reduce the power utilization, thereby it increases energy consumption. Several IR-UWB signals in the frequency spectrum are shown in Figure 2 and Figure 3 . As WSN system requires low power consumption, PAM modulation often use OOK method, which has simple structure. But OOK has poor performance on the BER(Bit Error Rate), anti-noise performance of BPM modulation such as anti-Jitter noise is better. ISI would be intensified if we adopted PPM under the conditions of intensive multi-path environment in the coal face. Therefore, we use BPM forms in the transceiver system of the coal face. A. The design of transmitting system The transmitter which adopts BPM forms is shown in Figure 4. The signal distortion, interference and noise brought by the special environment in coal face need encoded protection through channel coding interweave module. Data rate of the original information is lower, which make it difficult to meet the requirements of FCC in the absence of modulation. We need to use spread spectrum code transform the original information which has a larger duration ratio into a smaller duration ratio (nanosecond). Then we can generate BPM pulse signal through the pulse formation circuit, which can meet the requirement of FCC. Finally use filters to optimize BPM signal further to enlarge the spectrum and send it out from the antenna. The system uses Gaussian pulse to be the form of UWB signal. If a wave transmitted is the first order derivative Rayleigh pulse, the signal after sending out through the antenna is transformed to be the second order derivative of the Gaussian pulse in ideal circumstances. In addition, the lower the order of the Gaussian pulse is, the farther the signal can be sent under the same data rate. Here we select the Gaussian doublet, whose hardware circuit is relatively easy to implement and consume lower energy. Although interference of narrow-band communication system is exist in the ground wireless communications, the higher order of the Gaussian is , the better Gaussian narrow pulse shape. But we do not need to consider interference to the other narrow-band communications in the coal face, for so far, wireless communications systems is basically non-existent in the mines coal face. A second Gaussian pulse shape can be expressed as: Here, is used to express the pulse width, Suppose that the input signal is , each bit is expressed by and its cycle is.After the channel encoder, every bit of the sequence kare repeated by N times. The code duration time is , so each bit is composed by N pulse width. If we suppose the pseudo-random sequence of sensors node k is , the length of the sequence is N, the duration of the code slice is The sequence of can be replaced by and the .The time coordinate of i-th bit in the frame date stream sent by sensor node k is . when when .We can think in practical application.When N=1, the UWB waves and waveform sent are shown in the Figure 5. Waveform in the Figure from the top to the end is the UWB waveform (the waveform of code “0” and the waveform “1”); the waveform generated when several code are send out; UWB waveform when get through band-pass filter. B. The design of receiver system The recerver structure is shown in figure 6. The signal received through the receiving antenna will go through the low noise amplifier and filter. Then the amplitude of the signal will be detected using tunnel diodes peak detector. Then we can get a pulse waveform which own longer code duration time when the signal detected after passing through high-pass filter and pulse stretch circuit. The last step is sample and judge.In this design, we make use of the characters of the negative resistance region of tunnel diode. In this region, the current decreases as the voltage is increased. This negative resistance results in a very fast switching time. After detected by the tunnel and passed through high-pass filter and comparator, the signal can be stretched and delayed by RS latch. We can directly sampling and judge the signal, for the width of the signal we get is wider than we first received .The kind of the receiver is different from the method we previously used. Such as, literature 555 tell the technology about relevant receiver. As we know, the general complexity of the relevant receiver, which own integrator circuit and need precision clock, is much higher. Sometimes, general relevant receiver need matching filter according to channel model parameters, which can be required by channel estimation. Because channel characteristics under the mine well are extremely complex, the possibility to use channel estimation is small. In addition, the receiver does not need ADC conversion devices, for the comparator has fixed the position of the code “0”and”1”.Furthermore, the code stretched has a relative longer duration time, which do not need higher judgment pulse precision. Therefore, in the whole, the receiver does not need complicated channel estimation and ADC conversion devices, which make the energy-consumption and complexity much lower. But we can not ignore the disadvantage of this kind of receiver; it has bigger signal fading, lower detection efficiency. C. Anti-noise performance of BPM The propagation environment of the coal face belongs to dense multi-path. And the theoretical channel model we referred to is proposed by combining Saleh-Valenzu channel model, which is the foundation, and the characteristic of the coal face under the mine. Suppose the discrete pulse response is, r(t) is the signal received by one node. Then , . The distance between receiver and transmitter is about 5-8 meters, which can satisfy the requirement of the distribution of the nodes in the coal face. The code duration time is 25ns, the duration time of GASSION waves is80ps. Under this conditions , we can get the curve, just as shown in the Figure 8.In fact, when we carried out the experiment of BER test, the performance shown in Figure 8 is not easy to be seen because of the complexity of the channel character. According to the research result, the performance of anti-noise became abnormal, such as the fading of the signal is not in proportion to the distance and the amount of the path increase and decrease in a large scale. Because the relevant coefficient of transmitted waves of the BPM is passive relevance when we adopted relevant receiver, the performance of anti-noise of BPM in relevant receiver is superior to PPM and OOK. Take the structure simplification of the receiver and the special character of the coal face into consideration, BPM is preferable in the whole，ever if the receiver we discussed in this paper is not superior to the relevant receiver on the anti-noise performance. 3. Conclusion Because of the limited space of a non-uniform medium and the complicated channel character in the coal face, the choice of the model we send and receive the signal is extremely important. Taking into account that BPM do not have discrete spectrum when “0” and ”1” emerged in a same probability, if not, the amount of discrete spectrum is small, which is attractive to WSN system, for the low energy consumption is strongly required. Therefore, the communication mode can be used in the coal face. The Gaussian doublet, which can meet the requirement of FCC, is used to send the source signal. Take the complexity of the transmission channels, the receiver use non-coherent receiving method, use tunnel diode to detect signal, execute sampling and judgment after the signal go through the comparator and stretch circuit. This Method does not need channel estimation and ADC circuits, higher pulse sampling accuracy, which together decides the probability to simplify the structure of the receiver greatly. However, the method of receiving has a greater attenuation and bad anti-noise performance than the traditional relevant receiver. But lets takes every important factor into consideration, the receiving method is suitable for the special environment of the coal face. 中文译文采煤工作面无线传感器网络物理层设计UWB技术摘要为了保证安全生产的工作面，监测和监视采煤机，刮板运输机，液压支架，运输机械，破碎机等是必要的。目前，它是很难的电缆传输模式，以适应变化的工作场所的采煤工作面。因为各种各样的因素输电线路被损坏和折断，我们使用无线传感器网络（无线传感器网络） ，可以灵活的放置和可扩展性来解决这一问题。本文讨论了设计中的无线传感器网络收发工作面与UWB技术。这种收发器有一些有用的优势，如成本低，能耗低，结构简单，易于实现的设计，硬件，无需估计工作面通道的特点。然而，探测效率略低，但错误率能满足要求。1 、导言采煤工作面必须面对复杂地质条件和工作条件差等问题。为了确保安全生产的工作面，以监测实时面对采煤机，刮板运输机械，液压支架，转载机，破碎机和其他大型设备是必要的。此外，我们必须监测地面的压力、天然气、一氧化碳、灰尘及其他环境参数。同时，移动语音和图像通信是必需的。目前，信号监测来自于采煤工作面的电缆。由于面临正在持续不断的煤炭开采过程中，各种大型钢铁设备的采煤工作面需要推动和不断循环。空间的形状是不断变化在设备相对位置变化的同时。相应地，通讯电缆是难以适用于不断变化的工作场景，使输电线路损坏或终结频繁和使采煤工作面的移动语音和图像通信不可能。所有这些问题都造成许多潜在安全生产的麻烦。我们认为无线传感器网络（无线传感器网络）是可行的实施监测和监督的工作面，因为它有放置灵活，扩展简单，移动方便，自主调节等一些有用的特性。2 、无线传感器网络体系结构中的采煤工作面传感器网络系统结构的采矿工作面是如图1所示。图形中，该传感器节点发送的信息的采集，通过一个或多个跳跃的群集节点，基站（汇节点）负责数据的收集，并传输给任务管理节点，通过了插槽网络，任务管理节点负责综合处理数据，并对传感器网络发出指示。隧道工作面是一个有限的空间。支架，采煤机，运输和其他大型金属设备的布局和煤，岩石和其他媒体是一个非均匀受限制的空间，这一切使传输通道更加复杂，传输无线传感器节点的信号衰退和多路径的现象较为严重。这些是传感器网络在地面上不同的。因此，收发器的设计节点来说尤其重要。目前，有三个主要技术的物理层的无线传感器网络：窄带调制技术，扩频技术和超宽带（ UWB ）技术。虽然UWB技术具有一定吸引力的优势，如低功率谱密度，低复杂系统，低灵敏度的频道衰落，更好的安全性，等等。考虑到工作面的优势和特点，我们已经采用脉冲无线电超宽带公司（ IR - UWB ）技术，原因是： 1 ） UWB技术消耗低功耗和低功率谱。低功耗，低成本和小尺寸是最重要的特点，无线传感器网络节点。窄带调制技术，扩频调制技术，通常使用正弦载波，中频和射频电路中存在的系统，所以消耗更多的功耗比UWB技术。传输介质在采煤工作面是不统一的，这导致比无线通信系统在地面上更多的传输损耗。因此，低功耗变得尤为重要。在采煤工作面，作为无线传感器网络节点呈现带状分布，节点只需要沟通邻近节点。在无线传感器网络系统基础上的UWB ，消费较低的传输能量，能满足要求，并避免干扰对方在窄带通信节点。此外，低功耗和高穿透力帮助设计安全设备和传输救灾信号。 2 ）强大的抗干扰能力。在采煤工作面，电力及机械设备已分布较窄。当设备启动或停止，电器火花可能会导致大量的电磁干扰。因此，良好的抗干扰能力是强烈需要在无线通信中应用。3 ）良好的抗干扰多路径的能力。采煤工作面有一定的内在特征，如狭窄的空间，更多类型的媒体，多路密集的通道，而红外UWB可以适用于这一复杂的环境与发挥自己的优势：窄脉冲宽度，脉冲持续时间的比例小，高多路径决议，较强的抗多径和衰落能力。 4 ）结构简单。红外超宽带，如没有调制和上/下变频频率，发射器结构简单，能耗更低等特征，使其更加可以接受。根据复杂的节点和能耗纳入考虑，红外、UWB技术是非常适用于设计无线传感器网络物理层。因此，相比窄带调制技术，扩频技术，无线通信系统基于UWB技术目前在能源消耗，强度，抗多径和抗噪声等等方面有着良好表现。调节红外UWB的主要是脉冲幅度放大调制（ OOK ） ， PPM和BPM（双相位调制） ，但存在的脉冲幅度放大调制和PPM不仅使超宽带脉冲信号难以满足一定的频谱要求，还减少用电，从而增加能源消耗。几个红外超宽带信号的频谱如图2和图3 所示。由于无线传感器网络系统需要低功耗，脉冲幅度放大调制经常使用OOK调制方法，它结构简单。但是OOK一直表现不佳的误码率（误码率） ，抗噪性能的BPM调制如反抖动噪声更好。工业标准将会加强，如果我们通过手册的情况下，密集多径环境的采煤工作面。因此，我们使用BPM形式收发器系统的工作面。A、传输系统的设计变送器采用的BPM形式如图4所示。信号失真，干扰和噪音所带来的特殊环境工作面需要编码保护信道编码交织模块。数据传输速率的原始资料较低，这使得它在未模块化时难以满足FCC的要求。我们需要利用扩频码转换的原始资料，由较大的时间比转换到一个较小的时间比率（纳秒） 。然后，我们可以通过脉冲形成电路产生脉冲信号的BPM，可满足要
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