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Penetration of multimedia communications with mobile Wi-Fi and tethering requires wireless LANs (WLANs) to guarantee a specific bandwidth in densely deployed WLANs. IEEE802.11e (HCCA) with 802.11aa could use inefficiently radio frequency as well as fail to provide each WLAN with enough CFP period in which sending opportunity of a terminal is guaranteed. To guarantee a specific bandwidth even in densely...
In recent years, wireless LAN systems that utilize a wideband channel have been used in many cases, so that the problem of wireless LAN interference often occurs. In order to solve the wireless LAN interference problem, various interference management methods have been proposed. Among them, interference alignment algorithm is the most popular. In order to overcome the limitations of existing interference...
The fifth generation (5G) ultra dense network (UDN) is envisioned as a very dense deployment of low power base stations where heterogeneous radio access technologies are used to satisfy the data rate demand of users employing both licensed and unlicensed spectrum. In UDN scenario, conditions of the channels operating in licensed band may exhibit intermittent characteristics due to the varying level...
In dense wireless deployments, such as Enterprise WLANs (EWLANs) and home WLANs, interference may occur because of neighbouring WLANs sharing the same unlicensed spectrum. Mechanisms to centrally manage WLAN deployments cannot effectively mitigate the interference caused by hidden terminals (HTs) in WLANs that belong to different organisations. Furthermore, the impact of interference is amplified...
In this work, we introduce a powerful hardware-based rogue access point (PrAP), which can relay traffic between a legitimate AP and a wireless station back and forth, and act as a man-in-the-middle attacker. Our PrAP is built of two dedicated wireless routers interconnected physically, and can relay traffic rapidly between a station and a legitimate AP. Through extensive experiments, we demonstrate...
Multi-rate forward erasure correction (FEC)-applied wireless multicast enables reliable and efficient video multicast with intelligent selection of physical (PHY) layer data rate and FEC rate. The optimal PHY/FEC rates depend on the cause of the packet losses. However, previous approaches select the PHY/FEC rates by considering only channel errors even when interference is also a major source of packet...
With increasing demand for wireless connectivity, IEEE 802.11 WLANs have become ubiquitous and continue to grow in number. This leads to high density of basic service sets with the significant co-channel interference (CCI) among them. This paper sheds light on the CCI caused by 802.11 MAC ACK frames, which has been less studied than the CCI caused by data frames. Based on stochastic geometry analysis,...
Lately, ZigBee has been attracting attention as a short-range wireless communication standard. In a ZigBee network, it is necessary to suppress the packet transfer load because ZigBee needs to operate with low power consumption and within narrow communication bandwidth. On the other hand, in typical environments in which ZigBee is utilized, such as a smart home network, it generally coexists with...
This paper proposes an adaptive movable access point (AMAP) system to enhance the system capacity in dense wireless-device environments. In the proposed approach, the positions of access points (APs) are adaptively moved in accordance with clustered user distribution, which is sure to be effective in ununiform user distribution due to dense device environments. In order to derive the appropriate positions...
Densification of access points (APs) in wireless local area networks (WLANs) increases the interference and the contention domains of each AP due to multiple overlapped basic service sets (BSSs). Consequently, high interference from multiple co-channel BSS at the target AP impairs system performance. To improve system performance in the presence of multi-BSSs interference, we propose a decentralized...
The development of the technical devices of today is nearly impossible to follow. From all of these devices, drones received the highest publicity. The results of this fast-paced development is certainly favourable to hobby aviators and professional users as well. However this fast spreading brings up many questions on the technical side, for example the safe and stable communication is concerned...
This paper presents a simple and low-cost array antenna configuration. The proposed antenna configuration was designed to operate at the center frequency of 2.4 GHz for Wireless Local Area Network (WLAN) applications. The antenna consists of 2 couple conductor patches printed on the dielectric substrate placing in parallel and separate by the spacing between patch. The results have shown that the...
Wireless local area network (WLAN) uses carrier sens multiple access with collision avoidance (CSMA/CA) to share wireless medium. However, in dense WLAN environment, it occurs interference between WLAN nodes such as access points (APs) and stations (STAs). For resolving this problem, we propose management of WLAN APs by using open network operating system (ONOS) controller which is one of software...
WLAN can provide access to core network for mobile p hones, laptops and IoT devices. It becomes more necessary in some places such as office, shopping mall and stadium. Wireless devices need to connect with Access Point (AP) to obtain various kinds of service. Therefore, deployment of AP is important to guarantee QoS and user experience of the deployed WLAN. Most former works focus on signal coverage...
In this paper, we proposed a WLAN system interference evaluation model based on received signal power and working channels which reflects the system interference in the current channel configuration. Based on this model, we proposed a simple and effective channel assignment scheme in which a set of channels with minimum system interference values were selected as the APs working channels. Simulation...
Telecommunication has seen distinct upgrade since the innovation of wireless communication. The latest addition is LTE-Advanced. LTE-Advanced requires implementation of femtocell. Spontaneous femtocell deployment introduces cross-tier and co-tier interference as well as further cost for uniform installation. In this paper, we describe outlines to solve the encountered problems and discuss the feasibility...
Abstract-Unlicensed LTE system holds high potential to effectively offload data/video traffic from the crowded licensed band. Previous effort of deploying LTE in the unlicensed band (e.g. license-assisted access LAA) relies on one or more LTE carriers in the licensed band, and may not be desired in certain scenarios. This paper studies a new technology of utilizing LTE directly in an unlicensed band,...
Previously, we proposed the active access-point (AP) configuration algorithm for elastic Wireless Local-Area Network (WLAN) systems using heterogeneous APs. This algorithm activates or deactivates APs depending on traffic demands, assuming that any active AP can use a different channel to avoid interferences among APs. However, the number of non-interfered channels in IEEE 802.11 protocols is limited...
In this paper, QoS characteristics such as TCP throughput is investigated for densely deployed mobile wireless LANs (WLANs). Factors affecting throughput characteristics are discussed and evaluated by using real machines such as smartphones and portable APs. In IEEE 802.11 WLANs, a rate adaptation mechanism controls the transmission rate and one of the dominant factors for QoS. In order to understand...
In this paper, we present the beamforming technologies used for increasing the system capacity at unlicensed band. We investigate the international research trend and the key technology of some companies, such as Wavion, GoNet, and Ruckus Inc. We also introduce the Binary CDMA technologies good at PAPR characteristics. Finally, we analysis the performance of receive beamforming using Compact MIMO...
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