Frequency And Data Collision Detection And Fixing For Short Distance Transmission Of The Internet Of Things

The Internet of things (IoT) is a very popular topic in the world currently, and has beenincorporated into China’s12th five-year developing schemes, belong to one of the keynational strategic emerging industries. Internet of things simply refers to objects and objectsconnecting by virtue of the Internet; it’s one kind of network that some objects who is goingto transfer information must according to the relevant agreement to form a network throughinformation sensing device. Its main function is to sense and control the object in real-time.With the rapid development of Internet of things, the wireless sensor networks (WSNs) playa critical role. WSNs link the physical world and virtual world, perceive the change of thephysical environment around them. Therefore, we need to use modeling method to correctlydescribe the characteristics of WSNs and adapt to changing application environment. Ifconsidering the characteristics of the Internet of things “big data”, this model will need to beable to adapt to the large-scale WSNs network. At the same time, a very important challengeis the integration of Internet and WSNs. Therefore, this paper designed a kind of integrationof Internet and WSNs method and a modeling method for WSNs firstly, in this paper, thedesigned model can better adapt to the dynamic change of network and has the ability ofsearching for multiple optimal path. And proposed Extension Header Compression (EHC)method can compress the IPv6global address header and achieve the automatic allocationof IPv6address. In addition, in view of the dynamic change of network topology, themultipath data transmission mechanism and energy overflow problems etc, a cellularautomata model is put forward, based on the cell transmission model, this paper putsforward the information multipath transmission strategy in WSNs. The simulation resultsindicate that compared with6LoWPAN, the proposed EHC scheme has improvedthroughput obviously and reduced the energy consumption, and EHC scheme is moresuitable for the large-scale Internet of things environment; The experiment also simulatethree kinds of model: service centered model, cluster model and cellular automata model which is proposed in this paper, the experimental results show that compared with the othertwo models, cellular automata model has spent less time when transferred data and couldfind more paths.The Internet of things needs to adopt wireless technology to sense its front-end data. Inthe numerous wireless technologies, Bluetooth and Radio Frequency Identificationtechnology become to the key technical backbone of IoT depends on their characteristicssuch as low power, high speed, and environment adaptable stand out.Bluetooth works in a global unified open2.4GHz ISM band and it is susceptible tointerference with other device in the same spectrum. Because the Bluetooth piconet isindependent of each other, so the probability of using the same frequency will increasewhen in indoor environment which has more piconets. Because the FM series can be usedfor the piconet is also independent of each other, and information interaction also won’tproceed between piconets, therefore the piconet doesn’t know the frequency point which isused by other piconet at the same time, if several piconets have used the same frequency atthe same time then “frequency collision” will be occurred, namely the co-channelinterference, that will seriously impact on the performance of Bluetooth network and reducethe network throughput. This “frequency collision” needs the following three conditions:1)reference piconet and interference piconet to transmit data at the same time;2) the distancebetween interference piconet’s transmitting equipment and reference piconet’s receivingdevice is not more than10m;3) the same frequency carrier interference ratio (C/I) ofreference and interference piconet is less than11dB. The paper puts forward a frequencycollision repair method on channel switching for Bluetooth piconets. The method uses MSKmodulation instead of GFSK, and proceeds channel switching when retransmitting. In orderto analyze more completely, the method used the C/I value to judge whether the co-channelinterference accrued or not, and analyzed the co-channel probability between multipleBluetooth piconets by considering the return packets, frequency hopping guard time, threekinds of data packets coexistence etc, and analyzed the packet error rate (PER) andthroughput further. Simulation experiments show that using the frequency collision fixingmethods, when the distance of master-slave equipment is within10m in the referencepiconet, the C/I has improved obviously, at the same time, the PER has also reducedsignificantly; and the method also has good results when transmitting the mixed typegrouping. Therefore, the proposed method effectively reduced the PER, improved the C/Ivalue and throughput of reference piconet, increased the master-slave equipment’smaximum transmission distance free of co-channel interference, this is largely reduced therange with co-channel interference.Radio Frequency Identification (RFID) is a non-contact automatic identificationtechnology and playing a more and more important role in production, life, health and otherfields, multiple tags identification is the most outstanding character of RFID. But there will always be multiple tags around reader at the same time, when two or more tags send data tothe reader at the same time, it will be produce data conflict, namely “data collisions”,therefore the data anti-collision algorithm arises at the historic moment. Now the mainsolution to tag data collision are Binary Search algorithm and the ALOHA algorithm, thetwo algorithm ideas are tag active way, readers need according to the rules to read tags oneby one within its recognition scope, and the complexity of the two algorithm are all higher,and the overhead and time delay will increase with the tag number increasing. Therefore,how to reduce the system overhead and time delay, improve the system throughput is theproblem of RFID. Aiming at the shortcomings of the traditional anti-collision algorithm, toimprove the efficiency of reading tags, the paper puts forward a way of tag reading—UIDlisted reading mode, the reader reads tags initiatively, With putting the UID of tags to beidentified into the address list of a RFID reader，which was formed in advance，the addresslist would be tracked and searched until all of the tags were identified one by one，accordingto certain rules．The paper expounds on three reading modes of UID-listed reading: secondread mode, circulation mode and nested mode. To prove the strong points of the UID-listedreading mode proposed，query times，transmission delay and system efficiency weresimulated. Compared with the binary search algorithm, the method has relatively stablepaging number, the lower transmission delay and constant system efficiency. Theconsequences of simulation indicate that the UID-listed reading mode turns out to be betterthan the classical Binary Search algorithm．In addition, the proposed method also has activelookup function, so UID-listed reading mode has more advantages.