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In this paper, we consider the operation of the Long Term Evolution (LTE) systems in the unlicensed spectrum. Given the lack of the exclusive use of the spectrum, the operation in the unlicensed band is fundamentally limited by interference from other technologies using the same frequency band. By noting that the unlicensed spectrum is heavily used by Wireless Local Area Networks (WLAN), here we focus...
Two evolutionary algorithms are proposed in this paper to handle with access point channel assignment in Wireless Local Area Network. The objective considered is to minimize the maximum level of interference experienced by the users. Two deterministic heuristics, commonly employed in the considered problem, are used as benchmark. The paper is focused on the IEEE 802.11ac standard, which operates exclusively...
The rate control mechanism is an effective way to improve the overall system performance in IEEE 802.11 multi-rate networks. However, in dense environments, due to the large number of contending nodes, the packet collisions trigger unfairly the rate control mechanism to decrease the transmission data rate. In this work, we address the performance degradation problem of rate control caused by these...
The demand for wireless communication in enterprise network has been increasing with the advent of "smart working environment." In enterprise wireless network, high density of access points (APs) and limited frequency resources raise the significance of radio resource management. In this paper, we propose a centralized algorithm, named JACPoT, for jointly executable transmission power control...
Access Point (AP) selection is important in WLANs as it affects the throughput of the joining station (STA). In this paper, we propose a class of AP selection algorithms to maximize the joining STA's expected throughput by considering interference at STAs, and transmit opportunities (TXOPs) at APs. Specifically, we collect a binary-valued local channel occupancy signal, called busy-idle (BI) signal,...
The IEEE 802.11 Distributed Coordination Function (DCF) is based on the Carrier Sense Multiple Access (CSMA) algorithm for avoiding collisions of frames. In CSMA, spatial reuse can be improved by suitably changing the carrier sense threshold (CST). If the increased CST does not incur collisions and helps concurrent transmissions from multiple devices, this improves the throughput of the wireless LAN...
IEEE 802.19.1 coexistence system provide two types of coexistence service: information service vs. management service. Information service provides radio environment information that enables 802.11af APs to facilitate channels with its neighbor APs. Each AP determines its operating parameters by itself to mitigate interference using the information. On the other hands, with management service, coexistence...
We describe an empirical study findings on the impact of throughput performance when transmission power is adjusted among access points in close-proximity network devices. The experiment was conducted in an office environment to emulate a dense wireless LAN network. We introduce a power adjustment mechanism based on cognitive learning one of the attributes which then triggers the power selection....
This paper investigates Quality of Service (QoS) of personal mobile wireless LANs (m-WLANs). QoS characteristics in densely located WLAN are found to be significantly different from that in traditional WLANs. The channel assignment method is proposed and evaluated by using real devices to accurately evaluate the interferences for the total throughput of the densely located m-WLANs.
With the increase of wireless communication, the possibility to measure Over-the-Air receiver performance under the influence of an interfering signal becomes more and more important. Different devices and base stations are interfering with each other, but interference can also be internally within one device, for example between LTE and Wireless LAN. In this paper, measured results on LTE, WLAN and...
In this paper, theoretical analysis of network throughput of IEEE 802.15.4 enabled wireless sensor networks under WLAN interference shall be introduced. Analysis of achievable network throughputs is presented under multiple network configurations and WLAN interference scenarios.
Inserting attenuators between transceivers and antennas is proposed to improve spatial channel reuse in carrier sense multiple access with collision avoidance based WLANs. Using attenuators enables the access points or stations to decrease the powers of transmission signals and received signals, which equivalently results in the increase of the carrier sense threshold. Thus, the attenuation value...
In a dense WLAN deployment, the interfering wireless access points (APs) need to efficiently share the spectrum, and hence, avoid low-performance experience of users due to high collision rates and long backoff overheads. In this paper, we aim to propose a channel assignment scheme in which APs can self-configure their channel choices to mitigate interference and thereby maximize network throughput...
Since wireless local area network (WLAN) can support high transmission rate with low cost, the use of WLAN is increasing rapidly. The WLAN has become very congested, and in the dense environment, Overlapping BSS (basic set service) problem may be introduced, which will severely degrade the performance of the network. Transmission power control (TPC) of AP (Access Point) is considered as one of the...
Sensor networks using ZigBee are vulnerable to interference with Wi-Fi because ZigBee and Wi-Fi use the same frequency band. Other studies have measured the performance in an environment where Wi-Fi and ZigBee coexist, and some methods have been proposed to reduce the effect of interference by changing the timing of ACK and MAC parameters. However, conventional methods are not easy to implement. In...
In WLAN systems, distributed coordination function (DCF) is used to avoid transmission collision. When an error occurs, the transmitter extends its contention window for the next retransmission to avoid more errors. But this may cause an unfairness problem; in noisy conditions MTs may find it difficult to get transmission opportunities, especially in a heterogeneous network with a large number of...
The first giga-bit class wireless local area network (wireless LAN) below 6 GHz frequency (the IEEE 802.11ac standard) is attracting attention due to its capability of handling much more of the rapidly growing data traffic. The increased density of wireless LAN access points (APs), however, has induced inter-cell interference that severely degrades system performance. This problem seems to be getting...
Using unlicensed spectrums is a key factor in popularity of WLANs. Meanwhile, the interference is becoming severer in coming time because of network expansion. Assigning channels for AP in distributed way only reduce interference around single AP rather than reducing system interference. However systematic optimizations usually require real-time information which increase complexity for applying....
The increased use of wireless local area networks has led to an increased interference and a reduced performance, as a high amount of access points are often operating on the same frequency channel. This paper presents a network planning algorithm that minimizes the number of access points required for a certain throughput and optimizes the frequency allocated to each AP, leading to reduced interference...
Nowadays, the request for wireless services is greatly exploded to receive a good services from internet. So, many APs for WLAN are thoughtlessly deployed in various places. At this environments, inter-basic service set (BSS) interference might be happened. If the APs locating in same overlapped region are operated in the same channel, the CSMA/CA is well worked, that is multiple APs are operated...
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