Infrastructure Mode Research Articles

D2D pervasive communication system with out-of-band control autonomous to 5G networks

D2D (device-to-device) communication is one of the developments of 5G networks (5th generation mobile networks) that reduce mobile traffic load, reduce energy consumption and effectively use the available electrical radio spectrum. An increase in the number of mobile devices might, in theory, promote D2D communications to 5G networks; however, in practice, the D2D communications technologies, such as Wi-Fi Ad-Hoc, Bluetooth and Wi-Fi Direct, are not available or require human interaction. To overcome these limitations, a middleware based on Wi-Fi infrastructure mode, which establishes connections and performs data exchange without human interaction, is presented. Practical proofs of the concept demonstrate that the middleware enables transparent D2D communications for 5G applications.

Survey on Load-Balancing Methods in 802.11 Infrastructure Mode Wireless Networks for Improving Quality of Service

Traffic load in any 802.11 infrastructure mode network is typically distributed unevenly between access points (APs), creating hotspots. This is due to the inherent nature of wireless area networks (WLANs), where stations are free to associate to any known AP they desire, and the lack of control by the APs themselves. This imbalance creates a condition where affected APs in the network suffer traffic congestion while others are underutilized, leading to stations experiencing lower throughput, longer latency, and operating below the network potential capacity. To alleviate this problem, some form of load balancing is required to redistribute the work load among other available APs in the wireless network. This article presents a survey of the various works done in performing load balancing in an infrastructure mode wireless network and will cover the common methods including admission control, association management, cell breathing, and association control. Updates to the IEEE standards are also presented that support load-balancing efforts. Finally, software-defined networks are investigated to determine the extent of control integration to support managing and load-balancing WLANs. Trends in load-balancing research are also uncovered that indicate how the introduction of new wireless standards influences the amount of research.

Heuristic Based Power Consumption Minimisation and Optimisation on Smartphones

In the direction of capable save the energy of battery life in Smartphone accurate with sensible influence form of Wi-Fi data communication in infrastructure mode. The network environment parameters like still time in a 3G system the network throughput and the convey pattern have been accepted all through measurement study the collective impact of an issue has not been systematical.

Clock Synchronization Over IEEE 802.11—A Survey of Methodologies and Protocols

Just like Ethernet before, IEEE 802.11 is now transcending the borders of its usage from the office environment toward real-time communication on the factory floor. However, similar to Ethernet, the availability of synchronized clocks to coordinate and control communication and distributed real-time services is not a built-in feature in WLAN. Over the years, this has led to the design and use of a wide variety of customized protocols with varying complexity and precision, both for wired and wireless networks, in accordance with the increasingly demanding requirements from real-time applications. This survey looks into the details of synchronization over IEEE 802.11 with a particular focus on the infrastructure mode which is most relevant for industrial use cases. It highlights the different parameters which affect the performance of clock synchronization over WLAN and compares the performance of existing synchronization methods to analyze their shortcomings. Finally, it identifies new trends and directions for future research as well as features for wireless clock synchronization which will be required by the applications in the near future.

Does private investment in the transport sector mitigate the environmental impact of urbanisation? Evidence from Asia

Urbanisation serves as a pillar for creating prosperous economies, but its impacts on infrastructure and the environment have been a concern for policy makers. There are numerous studies that examine the impact of urbanisation on the environment but no known study has analysed whether the impact of urbanisation on the environment is dependent on the characteristics of available infrastructure. To address this gap, this study uses the STIRPAT model, panel cointegration and fully modified ordinary least square (FMOLS) estimator as well as panel data of eight Asian countries to analyse whether private sector investment in the transport sector and transport infrastructure mode influences the impact of urbanisation on transport CO2 emissions. We find that the effect of urbanisation on transport CO2 emissions depends on the covariates in the model and interactions with other factors. Increase in income and population increases transport CO2 emissions while technological improvements reduces CO2 emissions from the transport sector. Private sector investment in the transport sector and availability of rail infrastructure reduce transport CO2 emissions; and given the same level of urbanisation, Asian countries with more rail infrastructure and private sector investment in the transport sector tend to have lower CO2 emission from the transport sector. Policy makers in Asia should make efforts to boost private sector participation in the transport sector and also promote the construction and improvement of rail infrastructure in order to reduce urbanisation-induced transport CO2 emissions.

On the uplink outage throughput capacity of hybrid wireless networks with Massive MIMO

In this paper, we investigate theoretical transmission capacity limit of the uplink hybrid wireless network under infrastructure mode. Massive MIMO technology is assumed to be equipped on the base station to further increase the whole network throughput. Multi-user MIMO is preferred over Point-to-Point MIMO to achieve improved scalability and simplify UE design. Another perspective of this paper is to include the fading effect on capacity. Under favorable propagation condition, Massive MIMO greatly mitigates small scale fading effect between each user and base station antenna. Then closed-form outage capacity over large scale fading channel is derived in both low SNR and high SNR scenarios.

Lightweight, ECC based RFID Authentication Scheme for WLAN

Wireless local area networks (WLANs), like IEEE 802.11, are right now very common in numerous outdoor or indoor environments for providing wireless communication among WiFi-enabled devices by accessing an Access Point (infrastructure mode) or through peer to peer connections (ad hoc mode). Authentication is one among the most primary research challenges for the realization of the envisioned mobile and wireless Internet. This is mainly due to the latency delay introduced during the authentication process, which are of major concern for real-time applications and media streaming application. In the same way, it is also crucial for WLANs to authenticate clients and build secure channels with them. In the historical researches, the traditional authentication mechanisms frequently adopted the names and passwords of clients as login authentication. However, these Single Factor Authentication mechanisms are proved to be defective. In virtue of enhancing security, recent researches on authentication are built on Two-Factor authentication schemes. In this paper, the authors proposed a two factor, lightweight RFID authentication scheme based on elliptic curve cryptography (ECC) for WLAN. The analytic comparison demonstrates the research not just reduces the expense of proposed authentication schemes, yet gives security similarly as smart card technology. In addition, the performance of the proposed authentication scheme will analyze in terms of computational cost, communications cost, and storage cost.

Context-aware cooperative testbed for energy analysis in beyond 4G networks

The complexity of heterogeneous wireless networks in synergy with battery powered mobile devices is driving new stringent requirements in terms of power efficiency to ensure that battery life, environmental and thermal criteria can be met. Modern mobile devices are equipped with multiple interfaces, which allow them to exploit the benefits offered by heterogeneous networking environments, but on the other hand, drain battery swiftly. In this paper, architecture for a context-based node and a testbed platform for the analysis of energy consumption of heterogeneous cooperative communications are presented. The demonstrative testbed comprises a WiFi Access Point, which provides WiFi coverage in the infrastructure mode, as well as nodes capable of communicating through short-range ultra-wideband WiMedia. The testbed includes a context aware module that provides and stores information related to different nodes in the system. The paper shows how context information can be used to save the energy of mobile devices and extend their battery lifetime using short-range communications. The testbed is used as a proof-of-concept for the practical implementation of the cooperative communications concept. The obtained results show that significant amount of energy can be saved using context information along cooperation among multiple interfaces, in comparison to direct communications.

Throughput Improvement of 802.11 Networks Via Randomization of Transmission Power Levels

Successive interference cancelation can resolve collisions involving multiple packets and, hence, improve the throughput of an 802.11 network. This technique, however, requires packets to be sent with different power levels. In this paper, we first develop a detailed analytical model to determine the throughput of 802.11 networks with this multiple-packet reception capability. We then study the problem of determining the optimal probability distribution associating with these power levels when the network is operated in infrastructure and ad hoc modes, respectively. In the infrastructure mode, the problem is formulated as an optimization problem with a solution to be broadcast to all the nodes by the access point. In the ad hoc mode, the same problem is formulated as a mixed-strategy game, where individual nodes strategically choose the probability distribution of the transmitting power levels to maximize its own throughput. We show that the Nash equilibrium of this game is Pareto optimal and fair. Furthermore, the resulting throughput of the distributed approach is close to the optimal performance of the infrastructure mode.

Energy Efficiency Tradeoff Mechanism Towards Wireless Green Communication: A Survey

Energy efficient (EE) communication has earned tremendous interest in recent years due to ever increasing number of wireless devices operating in shrinking cells, while demanding high data rates with high Quality of Services (QoS) and Quality of Expectation (QoE). To support these objectives, energy is consumed in every protocol layer. Establishing and maintaining a successful wireless communication link to simultaneously achieve all these objectives becomes challenging since the energy consumption requirements of the user and network are different for different objectives. Thus, there is a need for tradeoff techniques to achieve energy efficiency in each protocol layer. In this paper, we provide a survey of different tradeoff mechanisms proposed in the literature. The EE tradeoffs have been classified based on each protocol layer and discussed its affect in the network energy efficiency. These other QoS parameters include spectral efficiency, deployment, delay, routing, scheduling, bandwidth and coding etc. This survey also discusses the various EE techniques to improve energy-efficiency in infrastructure mode. Finally, the work provides an discussion, where impact of EE tradeoffs have been presented based on different wireless architecture towards realizing a green wireless communication network.

Channel Allocation in Multi-radio Multi-channel Wireless Mesh Networks: A Categorized Survey

Wireless mesh networks are a special type of broadcast networks which cover the qualifications of both ad-hoc as well as infrastructure mode networks. These networks offer connectivity to the last mile through hop to hop communication and by comparatively reducing the cost of infrastructure in terms of wire and hardware. Channel assignment has always been the focused area for such networks specifically when using non-overlapping channels and sharing radio frequency spectrum while using multiple radios. It has always been a challenge for mesh network on impartial utilization of the resources (channels), with the increase in users. The rational utilization of multiple channels and multiple radios, not only increases the overall throughput, capacity and scalability, but also creates significant complexities for channel assignment methods. For a better understanding of research challenges, this paper discusses heuristic methods, measurements and channel utilization applications and also examines various researches that yield to overcome this problem. Finally, we highlight prospective directions of research.

Cooperative and cognitive wireless networks for train control systems

With recent advances in wireless networks, communication-based train control (CBTC) has become a popular approach to ensure the safe and efficient operation of railway trains. The requirements for train---ground communication in CBTC systems are stringent. Most existing works about train---ground communication systems consider the infrastructure mode without train---train direct communications. Due to unreliable wireless communications and frequent handovers, existing CBTC systems can severely affect train control efficiency and performance, as well as the utility of railway. In this paper, with recent advances in cooperative and cognitive wireless networks, we propose a CBTC system to enable train---train direct communications. In addition, the proposed cooperative and cognitive CBTC system is optimized with the cognitive control method. Unlike the exiting works on cooperative and cognitive wireless networks, in this paper, train control performance in CBTC systems is explicitly used as the performance measure in the design. Reinforcement learning is applied to obtain the optimal handover decision and adaption policy of communication parameters. Simulation result shows that the performance of train control can be improved significantly in our proposed cooperative and cognitive CBTC system.

Cluster Connectivity Assurance Metrics in Vehicular ad hoc Networks

Many applications introduced by Vehicular Ad-Hoc Networks (VANETs), such as intelligent transportation and roadside advertisement, make VANETs become an important component of metropolitan area networks. In VANETs, mobile nodes are vehicles which are equipped with wireless antennas; and they can communicate with each other by wireless communication on ad-hoc mode or infrastructure mode. Clustering vehicles into different groups can introduce many advantages for VANETs as it can facilitate resource reuse and increase system capacity. The main contribution of our work is a new strategy for clustering a VANET and improvements in many classical clustering metrics. One of the main ideas is the definition of a new optimized selection metric for the clustering of vehicular nodes, in the framework of Next Generation Vehicular ad-hoc Network. These metrics should select clusterheads which provide safe clusters and avoid collisions with adjacent vehicle nodes and intend to create stable clusters by reducing reclustering overhead and prolonging cluster lifetime

AP-Initiated Reservations for Performance Enhancement in 802.11 MAC

In the infrastructure mode of the IEEE 802.11 Wireless Local Area Networks (WLANs), usually an Access Point (AP) requires more transmission opportunities than mobile stations, since the AP relays all the data traffic among mobile stations. However, the current MAC protocol gives AP the same opportunity with mobile stations for channel accessing, and it may introduce unfairness in the infrastructure mode of WLANs. In this paper, aiming at resolving the unfairness problem and enhancing the network performance, we propose an AP-initiated reservation scheme. Our scheme gives a high priority for AP's channel accessing and allows AP to transmit multiple frames at once. We develop an analytical model to study the performance of proposed scheme, and also perform extensive simulations. Both the analytical and simulation results show that proposed scheme significantly enhances the performance of 802.11 MAC.

Proposing of Collisions Free and Secure Network for IEEE 802. 11 WLAN

wireless network contains various problems such as packets delay and drop because of collision due to the heavy traffic. Packets are dropped either by the buffer overflow or by the MAC layer contentions. Such packet losses decrease throughput. Packet delay is also a result of poor utilization of network capacity when it is integrated with routing algorithms. Routing protocol contains very serious security issues in adhoc network. SAODV, SEAR and SEED protocols are used for solutions. But when some security measures are taken it may results in decreasing the throughput. Even network security in infrastructure mode for Wi-Fi point is of great concern where pre-RSNA as well as RSNA methods fail to provide proper security. This paper simulates such problems in NS2 and proposes the model of securing and increasing the throughput with least delay. . + 0.2 0 1 Tcp 40 - 1 0.0 1.0 0 0 - 0.2 0 1 Tcp 40 - 1 0.0 1.0 0 0 r 0.210032 0 1 Tcp 40 - 1 0.0 1.0 0 0 + 0.210032 1 0 Ack 40 - 1 1.0 0.0 0 1 - 0.210032 1 0 Ack 40 - 1 1.0 0.0 0 1 r 0.220064 1 0 Ack 40 - 1 1.0 0.0 0 1 + 0.220064 0 1 Tcp 1040 - 1 0.0 1.0 1 2 - 0.220064 0 1 Tcp 1040 - 1 0.0 1.0 1 2 + 0.220064 0 1 Tcp 1040 - 1 0.0 1.0 2 3 - 0.220896 0 1 Tcp 1040 - 1 0.0 1.0 2 3 r 0.230896 0 1 Tcp 1040 - 1 0.0 1.0 1 2 1. s R send, receive, drop, forwarding - s / r / D / f

Design and Analysis of a Novel Hybrid Wireless Mesh Network Routing Protocol

Wireless mesh network (WMN) operates both in infrastructure and ad-hoc mode. It provides extended network coverage based on heterogeneous wireless technologies through multi-hop communications. In WMNs, the routing mechanisms and network organization need to be improved so that optimal path discovery or different protocols adaptability can be achieved. Hybrid routing is a demanding issue to be discussed these days as need of higher mobility management in the diverse situations and environments. It's required to improve the older schemes for higher data rate and minimum energy consumptions. The proposed work presents a design of a novel routing algorithm for optimal route discovery, congestion reduction, dynamic route selection and scalability in hybrid mesh networks. The authors have focused on Hybrid Routing Protocols to originate a novel routing scheme based on AODV (Ad hoc On-Demand Distance Vector routing protocol) in Ad-Hoc level with clustering scheme and DSDV (Destination Sequence Distance Vector) as proactive routing protocol in Backbone Mesh Router Level to form a new hybrid routing protocol. In this work a Novel Hybrid Distance Vector (NHDV) routing protocol algorithm has been introduced, which is the combination of DSDV (Destination Sequence Distance Vector) and AODV routing protocols. A clustering scheme with the combination of two efficient clustering schemes for Ad-hoc mesh client levels is discussed in detail and a performance metric for DSDV is also discussed which ETX (Expected Transmission Count) is for measuring packet loss ratio at each link for higher throughput. A new performance metric introduced in AODV as Mesh Router Count is used to improve the performance of communication to the Mesh Routers. The proposed work is the design of new algorithm that presents an optimal solution in bringing out a revolutionary change to Hybrid Routing.

Communication-Based Train Control (CBTC) Systems With Cooperative Relaying: Design and Performance Analysis

A communication-based train control (CBTC) system is an automated train control system using bidirectional train-ground communications to ensure the safe operation of rail vehicles. CBTC systems have stringent requirements for communication availability and latency. Most existing CBTC train-ground communication systems work in the infrastructure mode without train-train communications. Due to unreliable wireless communications and frequent handoffs, existing CBTC systems can severely affect train control performance, train operation efficiency, and the utility of the railway. In this paper, we use recent advances in cooperative relaying to enable train-train communications and, consequently, enhance the train control performance of CBTC systems. Trains act not only as end communication points but as relays for other trains as well. Unlike existing works on cooperative relaying, in this paper, linear quadratic cost for the train control performance in CBTC systems is considered as the performance measure. We jointly consider cooperative relaying and handoff decision issues in CBTC systems. Moreover, to mitigate the impacts of handoff latency on the train control performance, we propose an optimal guidance trajectory calculation scheme in the train control procedure that takes full consideration of the tracking error caused by handoff latency. Simulation results show that the train control performance can be substantially improved in our proposed CBTC system with cooperative relaying.

The Impact of Applying Cloud Computing to Archives Informatization

This article expounded the concept and characteristics of cloud computing technology, the influences on archives information infrastructure, archives service and utilization mode brought by cloud computing technology were mainly studied. Based on the present situation of cloud computing technology development, it also elaborated some problems in archives security and standardization.

A Study on Digital Archives Based on Cloud Computing

This article expounded the concept and characteristics of cloud computing technology, the influences on archives information infrastructure, archives service and utilization mode brought by cloud computing technology were mainly studied. Based on the present situation of cloud computing technology development, it also elaborated some problems in archives security and standardization.

Virtual Continuous CWmin Control Scheme of WLAN

In this paper, a priority control problem between uplink and downlink flows in IEEE 802.11 wireless LANs is considered. The minimum contention window size (CWmin) has a nonnegative integer value. CWmin control scheme is one of the solutions for priority control to achieve the fairness between links. However, it has the problem that CWmin control scheme cannot achieve precise priority control when the CWmin values become small. As the solution of this problem, this paper proposes a new CWmin control method called a virtual continuous CWmin control (VCCC) scheme. The key concept of this method is that it involves the use of small and large CWmin values probabilistically. The proposed scheme realizes the expected value of CWmin as a nonnegative real number and solves the precise priority control problem. Moreover, we proposed a theoretical analysis model for the proposed VCCC scheme. Computer simulation results show that the proposed scheme improves the throughput performance and achieves fairness between the uplink and the downlink flows in an infrastructure mode of the IEEE 802.11 based wireless LAN. Throughput of the proposed scheme is 31% higher than that of a conventional scheme when the number of wireless stations is 18. The difference between the theoretical analysis results and computer simulation results of the throughput is within 1% when the number of STAs is less than 10.