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Mobile/wireless virtual reality (VR) services, especially immersive 360∘ VR videos, have advanced unprecedentedly in recent years. However, the high bandwidth requirement of VR services has compounded the burden on wireless networks. Multicast is a high potential technique for alleviating the bandwidth requirement of 360∘ VR video streaming, but the multicast capacity is still constrained by the users with poor channel conditions, and it vanishes when the number of users increases while the number of base station (BS) antennas is fixed. To overcome the drawbacks of multicast, sidelink, which is an adaptation of the core LTE standard that allows the device-to-device (D2D) communications without going through a BS, can be utilized. In this paper, two sidelink-aided multicast scenarios (i.e., independent decoding and joint decoding) are studied for multi-quality tiled 360∘ VR video transmission. We propose a utility model for each scenario, and quality level selection, sidelink sender/receiver selection, and transmission resource allocation are optimized to maximize the total utility of all users under the bandwidth constraints as well as the quality smoothness constraints for multi-quality tiles. We then develop an iterative two-stage algorithm to obtain sub-optimal solutions to the formulated Mixed-Integer Nonlinear Programming (MINLP) problems. Simulation results demonstrate the advantage of the proposed solutions over several baseline schemes.

With the development of virtual reality (VR) technology, the future of VR systems is evolving from single-user wired connections to multi-user wireless connections. However, wireless online rendering and transmission incur extra processing and transmission latency, as well as higher bandwidth requirements. To meet the requirements of wireless VR applications and enhance the quality of the VR user experience, this paper designs a view synthesis-based 360° VR caching system over Cloud Radio Access Network (C-RAN), where both mobile edge computing (MEC) and hierarchical caching are supported. In the system, an MEC-Cache Server is deployed in the pooled Base band Units (BBU pool) and used for view synthesis and caching. In addition, the remote radio heads (RRHs) can also cache some video contents. If the requested content of a specific view is cached in the BBU pool or RRHs, or can be synthesized with the aid of the cached adjacent views, it is unnecessary to request the content from the remote VR video source server. Therefore, the transmission latency and backhaul traffic load for VR services can be decreased. We formulate a hierarchical collaborative caching problem aiming to minimize the transmission latency, which is proved NP-hard. To address the impractical expenses of the offline optimal method, an online MaxMinDistance caching algorithm with low complexity is proposed. Numerical simulation results demonstrate that the proposed caching strategy provides significantly improved cache hit rate, backhaul traffic load, transmission latency, and Quality of Experience (QoE) performances relative to conventional caching strategies.

In communications, innovative paradigm shifts have emerged in integrating various devices into the network to provide advanced and intelligent services. However, various security threats may occur that may not always be detected using traditional cryptographic techniques. Secure authentication is of paramount importance in modern wireless systems. This paper focusses on robust authentication in a time-varying communication environment where conventional authentication mechanisms are severely limited. We propose an Adaptive Neural Network (ANN) as an intelligent authentication process to improve detection accuracy. Specifically, a Data-Adaptive Matrix (DAM) is designed to track time-varying channel features. By utilizing a convolutional neural network as an intelligent authenticator, the proposed approach integrates deep feature extraction and attack detection, hence, leading to effective physical layer security. To evaluate the system, the ANN is prototyped on a universal software radio peripheral (USRP) and its authentication performance is evaluated in a conference room environment. Experimental results show that the ANN is effective in tackling the challenges of physical layer authentication under interference conditions, and is effective in time-varying environments.

Batman-adv (Better Approach to Mobile Ad-hoc Networking Advanced) routing protocol is a rapidly developing wireless Mesh network routing protocol in recent years. Due to its good portability, open source code, high dynamic organization and high security, More suitable for use in disaster relief, plateau shooting range and other places. When the routing criteria of the protocol are deeply studied, it is found that the protocol has a single criterion and is prone to instability when sending large-capacity data, causing frequent switching of routes, which in turn leads to packet loss. Aiming at this problem, the signal strength is introduced and the routing criteria are redesigned. The experimental results show that the new routing criteria can improve the stability of the routing protocol.

Batman-adv (Better Approach to Mobile Ad-hoc Networking Advanced) routing protocol is a Layer 2 routing protocol designed for wireless Mesh networks. It has been studied because of its open source code, good portability and stable performance. Scholars have a wide range of concerns. Aiming at the fierce channel competition problem of the Batman-adv routing protocol, a packet aggregation method is proposed. The protocol is applied to the OGM (Originator Message) packet discovered by the neighboring node, and the aggregation wait, aggregation judgment, and aggregation forwarding are performed on the basis of the direct forwarding of the protocol. Modification and implementation on the source code, and finally verified by experiments that the method has a great improvement on the channel competition of the protocol.

the mesh network has the characteristics of fast networking, flexibility, and controllable operation. The MAC layer protocol is the main factor determining the performance of the wireless mesh network. In the TDMA architecture, the MAC layer protocol mainly studies the slot allocation strategy. This paper mainly studies the current mainstream slot allocation protocols. Firstly, several strategies for time slot allocation are analyzed. Then, typical time slot allocation protocols are elaborated, and the advantages and disadvantages of the protocol are compared and analyzed. Thereafter, the key technology to the design of time slot allocation protocol is analyzed, and finally, the future development of the time slot allocation protocol is prospected.

Keywords: WiFi-MESH;802.11;CSMA/CA;TDMA;HWMP;BATMAN-adv Abstract. WiFi-MESH wireless network which are mainly based on the 802.11 protocols are developed quickly in recent years. The principle features, difficulties, directions and application schemes of the key technologies of WiFi-MESH systems, including MAC mechanisms and routing protocols, are analyzed and discussed. It can be concluded in the paper that the TDMA mechanisms based on 802.11 should be developed further for avoiding the collisions in essence, and the new BATMAN-adv routing protocol based on OSI architecture layer two may raise the performance of the systems more significantly than the HWMP routing protocol. Finally, some new technologies which could be used in WiFi-MESH are discussed.

Military professional education plays a key role in training high qualified military officer, the traditional education ideas has not been meet the requirement of the new military revolution. The problems such as traditional education values, role of teacher and students and teaching content system existing in the military professional education is concluded, the constructive teaching method is elaborated, and the approach to implement the constructive teaching in military professional education is discussed. Index Terms - Constructive Teaching, Military Professional Education, Problem, Implementation

The transmit control protocol is used more and more widely as the development of mobile wireless network IP based and the need of high reliable data transmission in the unstable environment, but it has a poor performance due to the complex wireless channel and the variable network structure. Two TCP enhancement modules named unilateral TCP-accelerate module and parallel TCP-accelerate module were designed and imported to a test wireless network and a 3G system after analyzing the shortcoming of standard TCP and summarizing the popular TCP enhancement technologies. It proved that the modules designed which are easy to employ and flexible can improve the performance of TCP significant and can be used for reliable and burst transmission of broadband data in the mobile wireless network IP based. KeywordsMobile wireless network; Unilateral TCPaccelerate; Parallel TCP-accelerate