Reliable Communication And Localization In Industrial Wireless Networks

Industrial wireless network(IWN)as one of the information interactive and gathering technology has gain a lot of attentions in the industry and academia society.The advantages of industrial wireless technology are low cost,easy to deployment and maintenance.In this paper,we focus on the hot rolling process industry,monitoring the equipments and collecting more process data.Industrial applications has a high requirement about the reliability,timeliness of wireless communications.Moreover,autonomous and reliable localization of wireless node in the industrial site is necessary for the effective deployment of IWN.In the 2.4 GHz ISM band,co-channel interference is very serious because of multi-radio coexistence.Moreover,the physical environment is complex and the channel is in deep fading and frequency selective fading because of lots of metal devices in the industry site.In this paper,we conduct research on reliable communication and positioning from physical and data link layer to solve the problems and challenges bringing by complex electromagnetic and physical environments in the industrial field.First,for the reliable communication of FieldNet of IWN,we design an CognitiveOFDM based industrial wireless network to improve spectrum utilization,allocate the spectrum based on demand and circumvent the ISM band interference to improve communication reliability.The Cognitive-OFDM network implements a periodic schedule,which includes interference detection,beacon transmission and data transmission.In the interference detection stage,we design a double windows difference edge detection method from frequency domain to detect the used subband of OFDM channel.In the beacon transmission stage,two different beacons are adaptively used to resist different interference situations.Without using a control channel,we design the preamble of beacon to help the receiver to identify the transmitted beacon.We implement the Cognitive-OFDM network in the software radio platform and evaluate its performance under interference,the beacon detection and decoding reliability can reach close to 100% with reasonable SNR.Moreover,we implement a Cognitive-OFDM demonstration platform,which can detect the interference and allocate available spectrum on demand.Second,for the real-time and reliable transmission from FieldNet AP to control system,we design an efficient and reliable wireless link to improve communication efficiency and reliability.There are three technologies,including:(1)based on the traditional stop and wait ARQ strategy,we propose packets pipelining transmission and accumulate acknowledgement strategy to improve the communication efficiency,(2)based on cognitive radio idea,we design an adaptive channel switching mechanism to avoid dynamic and unpredictable channel interference,(3)three different kinds of control information are integrated into a single acknowledgement packet to reduce communication overhead.We implement the wireless link in the software radio platform,in contrast to traditional communication links,communication efficiency increases by 3 times,the effective throughput increases by 4 times.Furthermore,we design a mobile monitoring system based on the designed wireless link,which can be used for environment monitoring and automatic inspection of industrial field.Third,for the localization demand of large scale IWN,we adopt dual-tone radio interferometric positioning technology and design two localization systems.Dual-Tone Radio Interferometric Positioning System(DRIPS)requires a few spectrum resource,and it is effective to combat the frequency selective fading in the industrial field.It is a low-cost and high accuracy localization technology.For the synchronized multiple anchors scenario,we design a Dual-Tone Radio Interferometric Positioning System using undersampling technique(uDRIPS).Moreover,we design a DRPIS for multi-target localization using a single mobile anchor(mDRIPS).Without using multiple synchronized anchors,mDRIPS can locate multiple targets at the same time.We evaluate the ranging feasibility of DRIPS in the software radio platform,which reaches centimeter level positioning accuracy,and we also verify the centimeter level positioning accuracy of the system through extensive simulations.