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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...
A typical home network environment has been built to assess and optimize WiFi antenna design for residential gateways. The measurement process is described and some examples illustrate interactions between antennas and their environment.
In this paper, we model power consumption of a heterogeneous network consisting of overlapped cellular and WiFi networks. Then, we propose a novel WiFi offloading model for maximizing per-user energy effciency in terms of bps per Joule. In the proposed WiFi offloading model, the heterogeneous network gathers user information and decides which portion of generated per-user traffic should be transmitted...
This paper presents a strategy to choose WiFi channels in urban areas. We consider (i) inter-channel interference where adjacent channels interfere with each other in WiFi systems and (ii) urban situations where many APs in different systems are deployed in an uncoordinated way. As it is often hard to identify the channel with less interference in such a situation, we present a channel scoring function...
In this paper the authors extend the tests and model verification related to the partially overlapped channel interference in Wi-Fi communications. Recently more and more papers have investigated the side effects of the channel interference on the throughput parameter. The paper proposes a theoretical model and an experimental approach to obtain useful information regarding channel allocation and...
Power-line communications are becoming a key component in home networking. The dominant MAC protocol for high data-rate power-line communications, IEEE 1901, employs a CSMA/CA mechanism similar to the back off process of 802.11. Existing performance evaluation studies of this protocol assume that the back off processes of the stations are independent (the so-called decoupling assumption). However,...
In this paper, we propose "Virtual Duplex, " a wireless architecture which, like Frequency Division Duplex (FDD), divides spectrum resources into two sub-bands. However, in contrast to FDD, both bands in Virtual Duplex are physically bidirectional, and transmissions are allocated to the bands according to whether they correspond to download or upload traffic. The "download data channel"...
IEEE 802.11aa amendment introduces several protocols to increase the robustness of multimedia traffic delivery for multicast destinations. According to the recent investigations Block ACK protocol is the most efficient among them. However, it requires polling to each of the multicast group member which may cause significant overhead in the scenarios with large group size. Compared to the polling based...
In Wireless Local Area Networks (WLANs), providing seamless mobility and balancing load among Access Points (APs) are challenging issues due to simple signal strength based association and hand-off mechanisms employed at wireless clients. Extensions to Software Defined Networking (SDN) framework for wireless networks could help to address theses issues in an efficient and cost-effective manner with...
Contention-based MAC protocols are adaptive to network changes but are inefficient due to frame collisions. On the other hand, reservation-based MAC protocols have advantage of collisions-free transmissions but lack flexibility. In this paper, we propose a novel hybrid contention/reservation-based MAC protocol in WLANs, called IO-MAC, which allows the coexistence of variable reservation period and...
As the contention resolution scheme in IEEE 802.11, binary exponential back off (BEB) has long been criticized for its high collision probability in saturation situation. In this paper, a novel contention resolution algorithm is designed to overcome its disadvantage. The cause of BEB's poor performance is identified as the overlapped back off intervals of stations and the restoration of contention...
This paper evaluates the quality of service (QoS) in Wi-Fi networks considering medium access control algorithms. It provides the wireless local area networks (WLAN) traffic analysis based on hotspot statistics. It also studies the distribution of physical layer frame arrival time and channel utilization time. The results show the presence of self-similar distribution dramatically influencing the...
This paper evaluates throughput characteristics of a multi-hop network, where a relay node itself has own traffic as well as relays transit traffic. In addition, it also has an individual per-flow scheduling such as weighted round-robin scheme to send transit and own data farther. The best route is determined in terms of various QoS criteria such as total throughput and relay node throughput. Novelty...
Extending battery life for smartphones while using wireless networks is important. In this paper, we propose Comfort Route for Energy Saving (CRFES), which helps users extend the battery life of their smartphones by navigating to their destinations via Quality of Service (QoS)-compliant energy-efficient spots such as Wi-Fi spots. To create CRFES, we construct maps of Wi-Fi spots using logging software...
In this paper, we consider the cross-layer design of a cooperative medium access control (MAC) protocol for wireless ad hoc networks. In particular, we propose a cooperative MAC protocol which can work either in the cooperative transmission mode for unidirectional traffic or physical-layer network coding (PNC) mode for bidirectional traffic. By designing a suitable control frame exchange the proposed...
The connectivity of the user equipment is one of the important thing that must be keep by the operator. To maintain this connectivity, operator should be smart to determine the network infrastructure that is low cost, easy, and fast to be implemented. To solve those connectivity problem, in this study will be designed an ad hoc mobile phone network. In an ad hoc network mobile phone which is built...
Performance evaluation of IEEE 802.11 multi-hop wireless networks has been drawing significant attention in recent years whereas most studies ignore the interfering noise far away. However, since the packets may overlap in time in multi-hop wireless networks, the cumulative energy of the noise coming from far away can be high enough to affect the performance of the network. In this paper, we investigate...
In home networks, a variety of smart devices are connected to a WiFi access point (AP) and the oversized buffer of the AP causes high latency/delay jitter and reduced network throughput (known as the bufferbloat problem). To mitigate this problem, appropriate active queue management (AQM) algorithms should be implemented at the AP. In this paper, we conduct extensive simulation study on the performance...
With the fast development of modern society, intelligent terminals, such as smart phones, are going to be a part of our life. How to support these terminals with excellent network service is a serious problem and needs to be solved quickly. In all the solutions, mobile integration network which integrates fixed network and mobile network and can make full use of these two networks is a hot topic....
In ad hoc networks, radio interference and terminal' mobility can cause frame losses. When the frame losses occur continuously, general datalink layer protocols regard it as a link failure and then notify it to network layer protocols. In conventional routing protocols, a source terminal initiates route discovery process to recover from the link failures on receiving the notifications even if the...
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