Collision Resolution In Near Field Random Multiple Access Wireless Networks Based On UHF FM0 Code

In the Internet of Things,single sensing node versus multi-physical node is usually a kind of wireless near field communication network,among which the radio frequency identification(RFID)communication network is the most common one.This network generally adopts random multiple Access on the Media Access Control(MAC)layer to solve the conflict decomposition problem.However,the communication efficiency of this mechanism which directly resolves the conflict at the MAC layer is not optimal,because once it encounters a conflict,it will immediately re-transmit the signal until there is no conflict.Moreover,with the increase of the number of signal sources,its channel utilization rate will undoubtedly be greatly affected.Such a communication mechanism is not a good way to resolve conflicts in today's instant messaging era.The separation collision decomposition method can reduce signal retransmission and improve communication efficiency.It uses the mechanism of the MAC layer and the physical layer to work together to combat the wireless near-range collisions.In other words,when the MAC layer communication collisions occur,the collision can be separated in the physical layer to decode the correct source.In the separation type of collision decomposition,a good codec technology can effectively improve the performance of collision decomposition.However,these codec technologies usually need to estimate the channel fading coefficient or need to know it.However,in the complex and changeable environment of wireless communication,the channel fading coefficient of the signal cannot be predicted in advance.Moreover,even if the channel fading coefficient can be estimated,its estimation error will have a great impact on the success rate of collision decomposition and the complexity of the algorithm will increase.Therefore,this condition is not always satisfied in NFC.This paper presents a Finite symbol Separation victor than decoding(Finite-symbol Separation Viterbi Decoder,FSVD)collision decomposition methods,this method does not need to know the channel fading coefficient of signal,only by estimating signal matrix cluster formation dictionary can eliminate the uncertainty of signal Separation in order to get more accurate likelihood distance,so as to improve the accuracy of decoding.In particular,compared to MAC protocol collision separation,it does provide another technical route to improve the throughput of the system,namely: one is to improve throughput by reducing collisions,the other is to improve throughput by directly decoding collision signals and avoiding retransmission.And this technology route has been widely concerned,such as cross physical layer protocol,multi-packet reception and other technologies.Of course,the increase in the number of collision source signals and the increase in complexity will inevitably lead to the increase in computing time.However,with the rapid development of electronic technology,FPGA,high-speed computing hardware and parallel computing equipment can reduce the running time of the algorithm.Simulation and experiment,we use software radio built a high-frequency short distance wireless communication networks based on FM0 code,the experimental results show that this article FSVD throughput reached about 0.61,compared with the traditional ALOHA system throughput by about 0.25.In addition,through the software Radio(USRP N210)wireless network system and the parameters and program Settings of GNU Radio software platform,the collision signals of 2,3 and4 sources were collected in this project.Through algorithm experiments,the collision signals of 2 and 3 sources could be separated successfully in this paper.