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AsWireless Local Area Networks (WLANs) become denser and denser recently, the contention-based MAC protocol such as the IEEE 802.11 DCF, the de facto standard for the WLAN, should be modified to handle such dense WLANs. To this end, we consider a recently proposed novel MAC protocol called the Renewal Access Protocol (RAP) in this paper. With the RAP, we consider two strategies for resolving collisions...
The proliferation of broadband wireless accesses has enabled the provisioning of multimedia communication services. Yet, the increasing demand for group-based multimedia services requires the development of new architectures capable of seamlessly delivering multi-party content and overcoming the prevailing heterogeneity and dynamics of current and next generation communication networks. In order to...
In this paper, we investigate the performance of an ALOHA random access wireless network consisting of nodes with and without RF energy harvesting capability. We develop and analyze a Markov model for the system when nodes with RF energy harvesting capability are infinitely backlogged. Our results indicate that the network throughput is improved when the conventional nodes are underloaded. On the...
Interference management (RF management) remains one of the main challenges facing the design and deployment of large-scale WLAN. RF management involves the detection, estimation and control of power level, channel allocations and link schedules, to improve the performance of the wireless network. Among interfering links, one can find different types of dependencies. While some of these types can be...
In mature wireless LAN (WLAN) deployments, we show that introducing 802.11ac could have little benefit compared to existing 802.11n deployments. Using a testbed with common characteristics for a WLAN deployment, we compare throughput for 802.11ac and 802.11n (in both 5GHz and 2.4GHz bands). We find that 802.11ac has lower throughput than for 802.11n for our testbed configuration. We also provide an...
The evolution of wireless networks and the low cost of WiFi technology, have enabled a promising scenario for deployment of these kind of networks in rural areas, as an effective alternative to interconnect distanced sites above tens kilometers. This work presents the results of the performance evaluation of a network with WiLD technology, based on simulation and a deployment in the Andean region...
Recently, wireless local area networks (WLANs) have become ubiquitous. In high density WLANs, interference resulting from neighbor cells is a challenging problem which would affect the network performance. To get higher throughput, it is important to improve spatial reuse of the channels. Since transmit power control (TPC) may cause asymmetric links unless carefully designed, we demonstrate that dynamic...
WiMAX (World Wide Interoperability for Microwave Access) is a standard based technology based on IEEE 802.16 Air Interface. This standard is the future mode of mobile communication. Therefore, it is important to evaluate the performance of WiMAX in different scenarios. In this paper we have presented performance analysis of WiMAX for the CBR (Constant Bit Rate) traffic with and without mobility. Two...
Currently, mobile devices can process large amounts of data for watching high-definition video, browsing the Web, and downloading software. Wireless communication devices have become necessary because mobile devices such as smartphones enable people to retrieve data anywhere. Such a high level of convenience is accessible when quality of service is excellent, particularly when wireless network traffic...
Handheld and non-handheld devices, which are simultaneously online, constitute the regular clients of the campus wireless local area networks (WLAN). It is necessary to understand the patterns of the user distribution and the user behavior, and adopt better strategies to optimize the service, as well as to understand the students' daily life. This paper introduces a approach of understanding how campus...
In this paper we introduced two enhancement modifications to the well-known TCP Westwood fast retransmission and fast recovery mechanisms. Firstly, a new modification is introduced to fasten the fast retransmission procedure by preventing the TCP sender side from waiting the third duplicate ACKs to retransmit lost packets. Secondly, further modification is presented to achieve better recovery for...
This work aims to improve the performance of cooperative relaying in interference-limited multihop networks. The multihop network nodes are equipped with multi-rate and continuous power control capabilities. The existing technique does not yield significant performance gains with multi-rate and power control capabilities. To obtain the achievable throughput rates, a cross-layer flow-based framework...
To fully utilize the spectrum resources, dynamic spectrum access is found to be very helpful. In this paper, a continuous time Markov chain (CTMC) based dynamic spectrum access (DSA) scheme is proposed for interaction between primary and secondary users along with the imperfect sensing environment (false alarm and misdetection). Since, collision occurs between primary and secondary users because of...
As a widely used over-the-top (OTT) video technique, adaptive bitrate video streaming has attracted considerable research attention and efforts. Traditional bitrate adaptation schemes rely on quality of service (QoS) to assess video delivery quality. However, in this paper, we argue that QoS may not accurately reflect the user-perceived video quality, especially in time-varying wireless networks....
Video transmission over the heterogeneous networks faces many challenges due to available bandwidth, link delay, frame lost, throughput, reliability, network congestion. In video streaming it is important that the video stream must reach the users within allocated time and also without errors in video frames which leads to packet loss. Hence to avoid the packet loss and to enhance the Packet Delivery...
It is important to measure network performance in the whole network life cycle. In the development phase network architects can estimate how the network will work for desired number of users and their needs more accurately. In the implementation and testing phases network engineers can conduct a site survey and thus measure network performance in any given location. Spots with poor performance can...
Transmission Control Protocol (TCP) congestion control algorithm works well for the wired networks where most of the timeouts and 3-dupacks are the result of congestion. In the wireless networks, where random segment loss due to bit errors is a dominant concern, the arrival of duplicate acknowledgements or even the retransmission timeouts do not necessarily denote congestion. In those cases, throttling...
In this paper we present a framework for evaluating wireless network performance through emulation. The framework uses a hybrid design in which the PHY layer is represented by a probabilistic model, whereas the MAC layer is executed as a functional module. Actual network applications and protocols are employed in order to create realistic test conditions. We use WiMAX as a case study to show the feasibility...
Multicasting is one of the fast and simple ways of transmitting a same data to multiple people at the same time in the network which saves the transmission time. Since multicasting is taking part of transmitting to multiple people there are chances for creating vulnerability against various attacks. In the existing system, MKMP — Multicast Key Management protocol is used in which the session information...
In recent years, wireless networks have been utilized in many situations. However, further increase in network capacity is essential in order to transfer large volume of traffic demanded by many and various clients and applications. By introducing multi-channel environment, network capacity is increased. However, in cases that packet generation rates from wireless stations to a base station are different...
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