With the rapid development and wide applications of information and communication technologies, human production and life and social governance are evolving in the direction of digitizing, informatization, and intelligence.As one of the most widely applied wireless communication technologies, the wireless local area network (WLAN) needs to make further breakthroughs in the key performance such as data throughput, reliability, and latency and needs to add sensing functions and intelligence.The huge frequency resources of the millimeter wave (mmWave) band have injected new momentum into the development of WLAN.But the mmWave WLAN has also brought new technical challenges and requirements.Firstly, the WLAN development history was reviewed, and network structures, typical applications, development directions, and performance index requirements of WLAN in the future were summarized.Then, the characteristics of wireless channels in the mmWave band were given, and the new requirements and challenges for mmWave WLAN design were analyzed.Finally, some potential key technologies that may meet these challenges and requirements were discussed and prospected.

Passive internet of things (IoT) is the fundamentally enabling technology of promoting digital transformation and upgrading of industries.In recent years, passive IoT communication technology such as radio frequency identification has been widely used in asset management fields due to its advantages of low cost, zero power consumption, and easy deployment.In this context, passive IoT communication technology and the latest research progress were introduced, the potential evolution prospects of passive IoT were analyzed.Based on that, development bottlenecks and challenges of passive IoT communication were given, a novel passive IoT communication system with deep fusion of the cellular system was presented, and the key technology research directions of this field were proposed.It is aimed to inspire new thoughts for the development of passive IoT communication technology.

Passive backscatter communication can free wireless sensors from limited-life batteries and heavy manual maintenance, and will also reduce their hardware cost.Passive backscatter communication is one of the key technologies to realize the passive internet of things (IoT).Due to the limited resources of passive sensor nodes, how to use coding technology to improve system reliability has become a challenging problem for passive IoT.The coding and decoding technologies of passive nodes in the passive IoT were focused on.Firstly, the development history of traditional channel coding and the existing RFID channel coding and decoding schemes were systematically expounded.Then, three suitable coding schemes were selected for passive backscatter communication technology.Finally, the performance of these three encoding schemes were compared by simulation and the advantages and disadvantages were summarized.

The rapid development of wireless local area network technology has brought about new challenges that significantly affect the communication quality of wireless channels.Wireless channel quality is crucial for guiding routers in managing sudden congestion and selecting appropriate channels.A set of solutions using channel available throughput as an indicator was designed.Firstly, invasive data collection methods were used to collect channel data, and an artifical neural network was trained to estimate the available throughput of the channel at the current time.Subsequently, non-invasive data collection methods were utilized to collect channel data, and an improved recurrent neural network model was employed to predict the available throughput of the channel for a future period.Experiments on the real data show that the scheme can effectively estimate and predict the available throughput of the channel, providing guidance for router decisions.

In the multi-link non-simultaneous transmit and receive mode of next-generation Wi-Fi 7 protocol, the transmission ending time of multi-link device (MLD) needs to be aligned on each link, which may require data padding, resulting in the waste of spectrum resources and transmission energy consumption.A high energy efficient MLD transmission algorithm was proposed to improve the total energy efficiency of MLD station (STA) on the premise of meeting the data transmission delay limit.The proposed algorithm was optimized from the following three aspects: link data distribution ratio, communication resource allocation and STA transmission power.Simulation results show that the proposed algorithm can reduce energy consumption by reducing padding data on the premise of guaranteeing the delay limit of data transmission, and the transmission energy efficiency of the system is increased by about 150% compared with that of the baseline scheme.

At present, the importance and commercial value of wireless fidelity (Wi-Fi) technology have been widely recognized.And people are also pursuing better quality of service (QoS).Transmission control protocol (TCP) as a connection-oriented communication protocol that provides end-to-end reliability services, its importance is also increasing, and it is the dominant transmission protocol in the Internet.Besides, since the coverage of a single access point (AP) is limited, it is often necessary to extend the coverage through cascading in many scenarios.However, the current research on cascading scenarios is based on the user datagram protocol (UDP), which means that only downlink traffic exists in the scenario.Actually, uplink and downlink traffic often exist at the same time in many scenarios, which means TCP traffic is running.How to calculate the TCP throughput obtained by users in the cascading scenario has always been an unresolved problem.To solve this problem, firstly, a Wi-Fi throughput model under the condition of saturated TCP traffic was established in the cascading scenario, and the calculation of user throughput was realized through two Markov chains.Secondly, a cascading system was built and actual tests were conducted.The validity of the model is verified by comparing the theoretical simulation results with the actual test results.

In order to solve the problem that overlapping basic service set (OBSS) users are subject to serious co-frequency interference in the dense Wi-Fi network, resulting in low signal to interference plus noise ratio (SINR) of received signals, low data transmission rate or inability to transmit, a multi-access point (AP) joint transmission (JT) scheme based on improved genetic algorithm (IGA) selection of AP coordination set was proposed.Firstly, the SINR threshold method was used to divide all station (STA) in the system into central users and edge users, and the JT scheme was adopted for edge users.Then, with the goal of maximizing the throughput of edge users, IGA was proposed to determine the appropriate coordinated AP for each edge user to form its own AP coordination set, and maximize the potential gain of JT technology.The simulation results show that the proposed scheme can effectively reduce the co-frequency interference between BSS and improve the performance and throughput of BSS edge users in dense network.

Highly accurate and reliable indoor wireless positioning services have been widely used.In order to obtain good positioning accuracy, the design of positioning algorithms needs to be matched with wireless positioning facilities.fiber to the room (FTTR) is an indoor access network solution based on IEEE 802.11 ax, a new generation of wireless local area network (WLAN) standard.Compared with the existing Wi-Fi networks, FTTR has a much larger available band width.However, FTTR WLAN also lacks of a public valid data set to support localization functions, which makes the localization research based on FTTR scenarios face huge obstacles.In order to solve the above problems, firstly, a frequency response-based FTTR scene dataset generation method was proposed, which uses the existing Wi-Fi localization dataset to generate the frequency response matrix within the available band width of FTTR.Then, the parallel path principal component analysis (PCA) method was used to generate the classification matrix.And the generated dataset was trained using a fully connected neural network to improve the accuracy.The experimental results on the real measurement dataset show that the proposed localization algorithm can achieve a localization accuracy of less than 1 m, which is not only more accurate than the traditional location estimation algorithm, but also basically meets the fine-grained localization requirements for practical applications.

High-quality home wireless network with large bandwidth, wide coverage, low latency and anti-interference is the key indicator to ensure user experience of fiber to the room (FTTR) Gigabit optical network.Traditional home network equipment mainly adopts single-beam single-polarized antenna design, which has become increasingly unable to meet the needs of high-quality network products under the background of large attenuation and strong interference.Antenna, as an indispensable component to realize conduction energy and air-interface electromagnetic wave transformation, can realize multiple functions by using its design freedom.High gain can reduce the power consumption of the radio frequency (RF) side to achieve the purpose of energy saving, and multi-beam can maintain high-performance network coverage without dead ends.Therefore, designing a multi-beam antenna with small size, high gain and flexible usage is of great value.Following the practical engineering and current academic research, a multi-beam antenna based on spoof surface plasmon polariton (SSPP) technology, covering the 5.1～5.9 GHz frequency band of Wi-Fi, was designed for home network products.Compared with traditional antennas, the test results of the antenna based on SPSS technology show that the coverage performance of the network in weak signal scenarios such as through-wall and cross-layer scenarios is improved greatly.It has great application prospects in increasingly miniaturized home terminal products.

RAT-dependent is a satellite independent positioning technology of 5G.3GPP gives the Cramer-Rao lower bound (CRLB) of the positioning accuracy under the ideal condition of a single station and the simulation positioning accuracy of multi-station under different network configurations.Based on the actual network conditions, the analysis framework, accuracy range of multi-station positioning accuracy and the corresponding improvement method were proposed.The experimental results show that the RAT-dependent positioning accuracy is closely related to network technologies, and the positioning accuracy of the optimized scheme can be improved by 20%～30% compared with the non-optimized scheme.

As an urban artery and popular means of transportation, the subway is the most sustainable way of transportation.With the increase in operating mileage and passenger volume of subway and other rail transit, it faces greater challenges in operation, maintenance, security, scheduling, and other aspects.There is an urgent need for information technology to improve the level of subway operation services.While the foundation of subway informatization is effective indoor network coverage.At present, there are coverage requirements of multiple scenario such as outdoor wide area, indoor enclosed static scenes, and indoor enclosed high-speed sports scenes.For different coverage scenarios, if the same network method is chosen for coverage, there may be problems of high cost and poor coverage effect.Therefore, for the coverage of the subway network, it is necessary to flexibly combine macro station, micro station, room separation, leakage cable and other methods, combined with resource block (RB) guarantee, automatic handover, automatic login and other guarantee technologies, to meet the requirements of the network’s indicators such as insensitive switching, high data rate, low latency, high capacity, and large-scale connection under the optimal cost conditions, to ensure the normal operation of toB and toC business in subway scenarios.The 5G network stereo coverage scheme was studied in subway scenario, providing important reference for the coverage of other subway specialized networks.