Research On Key Techniques Of Indoor Hybrid Network Based On Visible Light Communication And Wi-Fi

Visible light communication(VLC)is a novel wireless optical communication technology,using LED rapid flashing to transmit data,which has 300 THz bandwidth utilized for high speed data transmission.Due to advantages of no electromagnetic interference,both illumination and communication,VLC becomes a powerful supplement for indoor wireless network access.However,the process of VLC technology is primary stage of situation,where VLC networking research should be improved and developed,for example that upward link access and optical link directivity are still not solved.Therefore,in this paper,a hybrid network solution based on VLC and existing indoor Wi-Fi technique is discussed to meet the user demand of high density and data rate,in that current indoor Wi-Fi network alone can neither reach the high transmission rate nor avoid the frequency interference.And this hybrid network will provide more access points and greater data bandwidth to accommodate more equipment and higher quality access.Detailedly,this paper explores the research on hybrid network system architecture,optimal relationship between the number of optical APs and LED lamps,channel resource allocation,and handover between VLC APs and Wi-Fi APs when user is moving or be sheltered.The relevant research results are summarized as follows:1.According to requirement of indoor illumination and communication in typical application scenarios such as home and office,the system architecture of VLC and Wi-Fi hybrid network is designed,and the arrangement of optical APs and the LED lamps are optimized for the throughput maximization.In this section,in order to meet the scalability of the optical AP number and minimality of the Wi-Fi system modification,the system architecture of hybrid network is designed,and the process of service transmission is described in details.At the same time,in the condition of typical square lamp layout,taking 10m*10m*3m's room as an example,a lighting layout optimization method based on the number of VLC APs is given,which covers an integrated optimization on lamp numbers,VLC APs and half power angles of luminescent to improve the optical link throughput performance.The simulation results show that the optimized optical link throughput is 16.7 times as that of a Wi-Fi AP while ensuring the effective lighting area and communication area.Compared to general layout of a lamp as a hot spot,the system throughput has been improved,which greatly improves the quality of service of users.2.Aiming at multi-user downlink channel allocations in a VLC and Wi-Fi hybrid network,a resource allocate algorithm combined with the power distribution of optical signals isproposed.Two different business types are considered: Delay-Constraint service(DC)and Best-Effort service(BE).In order to ensure the fairness of DC users' average throughput and maximize the minimum rate requirement of BE service users,the signal power of different optical APs is dynamically allocated by the distribution of users,then the Lagrangian multiplier method for iterative is utilized.Finally,the optimal channel allocation scheme for users can be derived from the unity function of system throughput.The simulation results show that our optical signal power dynamic allocation algorithm ensures a small amount of DC service user demand while BE business users of the total throughput and users' fairness have been significantly improved,compared to uniform distribution conditions combined with different channel selection algorithms(e.g.,iterative algorithm,maximum SINR principle and minimum distance principle).Moreover,the combination of optical signal power dynamic allocation and iterative algorithm has better throughput between user fairness and system performance balance.3.Aiming at downlink handover between VLC APs and Wi-Fi AP in the case of user moving or being blocked,a vertical switching algorithm for optical link based on fuzzy logic theory is proposed.Considering the four parameters including user current optical link SINR,statistical average SINR,user moving speed and user service minimum rate demand,the handover rules of downlink access is designed by the change of these parameters.According to the user data rate,average user switching times and user satisfaction,the simulation results show that our algorithm can achieve better performance compared to the existing method considering the SINR or identify the interrupt types alone.