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Wireless local networks (WLANs) that contain a high-density of access points (APs) are being deployed rapidly all around the world, where large numbers of idle APs exist. In this paper, a optimization for the deployment and transmitting power of AP is proposed in order to save energy and reduce frequency interference. It includes green AP clustering where Fuzzy K-mean algorithm is used, AP's second...
With the rapid growth of the Internet, deploying energy-efficient networking technology is an urgent matter. In particular, wireless LAN (WLAN), which is widely used due to its ease of deployment and low cost of installation, is also required to be energy efficient. For this purpose, R & D activities for Radio-On-Demand-Networks (ROD) have been proposed. In ROD networks, access points (APs) have...
In this paper we study the problem of throughput maximization, with fairness guarantee, in multi-cell WLANs with hidden terminals. In such a scenario, the throughput gained by each flow is generally determined by the four major control mechanisms that make the basis of WLAN control protocols - viz., radio frequency channel assignment, association control, intra-AP airtime sharing between the associated...
IEEE 802.11 WLANs are currently one of the most popular wireless technologies, but their immediate success results in dense deployments and high demand of user traffic. This in turn leads to decrease in throughput and poor spectrum utilization. Especially in the 2.4 GHz ISM band, where the spectrum is a very scarce resource, all available WLAN channels should be exploited in the best possible way...
In this paper we propose an algorithm to address the emergency case of an access point (AP) failure by adjusting a radio parameter of the neighboring APs. The goal is to minimize the coverage gap while at the same time: a) restrain imposed interference as much as possible and b) provide adequate load fairness among the APs. We assume an 802.11 infrastructure network where initially every mobile terminal...
Over the last few years, mobile wireless LANs (m-WLANs), which are characterized by portable access points (APs) and a small number of connected clients, are becoming popular. When a large number of such personal mobile APs operate close to each other, for example in crowded urban areas and conference venues, the quality of service (QoS) of the connected clients can be severely degraded due to co-channel...
The packet delivery ratio (PDR) performance of a wireless communication network interfered by a coexisting network is determined by the collision-time. In this paper, we propose a stochastic collision-time model for coexisting wireless networks, and analyze it in particular for coexisting low-rate wireless personal area network (LR-WPAN) and WLAN. Although, the packet collision-time of the interfered...
The low-power, low-rate ZigBee/IEEE 802.15.4 wireless sensor network (WSN) is vulnerable to the interference from a collocated wireless local area network (WLAN), which operates with considerably higher power in the same 2.4GHz Industrial, Scientific, and Medical (ISM) band. In this paper, a novel and effective Interference Aware Adaptive Clear Channel Assessment (IAACCA) technique is proposed to...
In this paper, we study the performance of successive interference cancellation (SIC) technique for random access based wireless local area networks (WLANs). We consider an IEEE 802.11 based carrier sense multiple access with collision avoidance (CSMA/CA) medium access control (MAC) protocol for MAC layer and a SIC technique at the physical layer. Via extensive simulation campaign, we investigate...
Wireless local area networks (WLANs) adopted IEEE 802.11 based carrier sense multiple access with collision avoidance (CSMA/CA) multiple access control (MAC) protocol. Throughput in a WLAN significantly depends on the minimum contention window (CW) parameter of CSMA/CA MAC protocol. Without considering the capture effect, i.e., by using a protocol model, G. Bianchi models the optimal value of the...
As the latest IEEE 802.11 standard, 802.11n allows a maximum physical data rate as high as 600Mbps, making it a desirable candidate for wireless local area network (WLAN) deployment. In WLANs, access points (APs) are often densely deployed, and thus neighboring APs should be assigned with orthogonal channels to avoid performance degradation caused by interference. It is challenging to find the optimal...
This paper presents the system performance analysis of 3GPP Long-Term Evolution (LTE) and IEEE 802.11 Wireless Local Area Networks (WLAN) in a situation where LTE downlink (DL) has been expanded over to unlicensed frequency band usually used by WLAN. Simple fractional bandwidth sharing mechanism is used to allow both technologies to transmit. The system performance is evaluated by means of fully dynamic...
Device-to-Device communication has been regarded as a promising technology to improve the cellular system efficiency, which allows mobile devices communicate directly with each other on the licensed frequency resources under the control of a base station (or eNB). However, the benefits of D2D using license exempt bands, such as ISM bands, have not been sufficiently taken into account yet. The main...
Flexible channels enable Access Points (AP) and clients to determine channel widths and their center frequencies. The key challenge in flexible channels is how to determine proper channel width and center frequency for each link demands such that the overall system throughput could be improved. In this work, we introduce a distributed flexible channel assignment algorithm, DFCA. Different from prior...
Enterprise WLAN consists of many APs connected to wired backbone network. Conventional DCF mechanism can not completely prevent conflicts between APs which cause large quantities of transmission failure and retransmission overhead. However, to keep compatible with 802.11-compliant clients, it is difficult to discard DCF. In this paper, we proposed a framework called DPS, which incorporates centralized...
Data rate adaptation (RA) schemes are the key means by which WLAN adapters adjust their operation to the variable quality of wireless channels. The IEEE 802.11 standard does not specify any RA preferences allowing for a competition in performance among vendors, thus numerous proprietary solutions coexist. While the RA schemes implemented in individual user terminals are unknown to the AP of a hotspot,...
This paper proposes an interference detection method in MIMO transmission, which utilizes periodical preamble signals in a frequency domain. In this paper, we assume the collision between the short preamble signal in WLAN system and interfering signal like a microwave oven. In the propose method, second antenna receives the signals while first antenna transmits the preamble signals. Hence, the interference...
Techniques for coordinated use of WiFi and LTE radio links are developed for operator-managed multi-radio heterogeneous networks. In particular, we consider deployments based on integrated small cells with co-located WiFi and LTE interfaces, which allow for tighter coordination between the two interfaces especially when used together with WiFi/LTE capable client devices. The paper develops a utility...
As the demand for high-throughput communications in wireless LANs increases, the need for expanding channel bandwidth also increases. However, the use of wider band channels results in the decrease of the number of channels available. Therefore, if multiple access points (APs) are in proximity and the cells overlap, it is difficult for each AP to use an orthogonal channel, and competitions thus increase...
IEEE 802.15.4, the basic standard behind ZigBee, is a low-power communication standard mostly operating in the free 2.4 GHz Industrial, Scientific and Medical (ISM) frequency band. This band is heavily used by many technologies sending with more power, therefore avoiding interference is an important task and knowledge of the spectrum is essential. This paper presents an algorithm and its actual implementation...
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