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Analytical models of the Distributed Coordination Function (DCF) have numerous applications in the performance analysis of IEEE 802.11 networks. The model proposed in this paper distinguishes itself from existing approaches in that it allows throughput, delay, and frame loss ratio analysis under both saturation and non-saturation network conditions. It combines the Markov chain and the queuing theory...
Traditional Medium Access Control (MAC) algorithms for Distributed Co-ordination Function (DCF) in IEEE 802.11 extend window ranges after each packet collision in the next stage. As these window ranges intersect with window ranges of other stages, the system is collision prone. This paper proposes a class of collision resolution schemes for 802.11 contention window control with multistep distribution...
IEEE 802.16 (WiMAX) and IEEE 802.11 (WiFi) are different wireless access technologies with the former being used in Metropolitan Area Networks and the latter used in Local Area Networks. With the increase in popularity of WiMAX and WiFi networks, it is expected that mobile devices in future will be equipped with these radios for data access. Such a scenario presents us with an opportunity to utilize...
The evolution of wireless access technologies, the increasing demand of users and services, and the evolution of terminals (which have the ability to connect to different access technologies), strengthened the need to use all the available resources in an optimal way. This paper presents a new approach that uses the combination of multihoming and network coding to improve the allocation of network...
For vehicular users, mobile data offloading through WiFi has proven its feasibility in reducing the data burden on the cellular networks. By delaying the data request for a while before resorting to the cellular network, the vehicular user can utilize the opportunistically available WiFi connections during the delay to serve its request An important question here is: how long should the user wait...
In wireless multi-hop networks, broadcasting by flooding generates frequent retransmissions of unnecessary packets that participate heavily in increasing contention and collision probability. These problems become increasingly likely in a wireless mesh network which can interface to other external networks, thus leading to a significant increase in broadcast traffic. In this paper we have focused...
Wireless Mesh Networks (WMNs) are currently attracting a lot of attention due to their ability to provide cost-efficient broadband wireless connectivity. In this paper, we evaluate the performance of a WMN by simulations considering packet delivery ratio (PDR), throughput and delay. For simulations, we used ns-3 simulator and Hybrid Wireless Mesh Protocol (HWMP). We evaluate the performance of the...
The Virtual Coordinate Multiple Access (VCMA) protocol is introduced and analyzed. VCMA is a medium access control protocol that defines transmissions schedules dynamically based on the assignment and exchange of virtual coordinates relative to an elected root node in a mesh network. VCMA is shown to attain feasible transmission schedules within a finite time, and its channel access delay properties...
Delay is a critical QoS performance metric for Multi-hop Wireless Network (MHWN). It is well known that schemes that give a higher data rate to the link with larger queue length can achieve high throughput performance. However, this queue-length-based approach may potentially suffer from large (even infinite) packet delays due to the subsequent contention problem caused by the next-hop arriving packets...
The IEEE 802.11v defines the Directed Multicast Service (DMS) in order to enhance the reliability of the multicast transport. This service converts multicast traffic into several unicast streams. Therefore DMS can be used to serve a limited number of receivers. In this paper, we show that using DMS, losses caused by queue rejections may exceed the packet loss rate of the legacy multicast. To resolve...
3GPP Release 9 has introduced a proximity detection feature where the User Equipment (UE) when so configured is able to determine its proximity to a Closed Subscriber Group (CSG) or hybrid cell. The proximity is determined for CSG or hybrid cells whose CSG Identity (CSG ID) is in the UE's CSG whitelist. The UE sends an “entering” or “leaving” proximity indication to the Serving Radio Network Controller...
Recent advancements in PHY data rates of communication technologies require efficient MAC mechanisms. IEEE 802.11 MAC compels nodes to defer transmissions to avoid collisions and maintain random and fair channel access. Contention time degrades network performance in terms of bandwidth and delays; this problem exaggerates at higher data rates. In this paper, we propose a frequency-domain backoff scheme,...
The spread of the Internet has given rise to strong demands for real-time services such as voice and streaming video. Since these services require guarantees that may include transmission rate, delay, and delay variance, the network, including the wireless access networks, must offer quality of service (QoS) guarantees. However, no radio access system fully supports QoS controls. In this paper, we...
The IEEE 802.11ai is an upcoming fast initial link setup (FILS) amendment that could enable a STA to achieve secure link setup in less than 100 ms. A successful link setup process will then allow the STA to send IP traffic with a valid IP address through the AP. In this paper, we first present a performance analysis on how well the legacy 802.11 can support FILS. We then demonstrate that the rate...
We exploit helper-to-helper (h-2-h) cooperation using the broadcast nature of wireless sensor networks. The potential helpers overhear the packet from the transmission of previous hop and the helper transmits the packet in the current hop on behalf of the assigned node (sender). We call it friendship relaying cooperative medium access control (FRC-MAC) protocol. This mechanism eliminates the sender...
Transport layer performance in IEEE 802.11 mul-tihop wireless networks (MHWNs) has been greatly challenged by wireless medium characteristics and multihop nature which are the sources of several types of packet loss including collision, random channel errors and route failures. Rate control transport protocols, the candidates for multimedia streaming applications suffer from high loss rates and end-to-end...
With an increase in number of vehicles on road, applications and services offered by Intelligent Transportation System are growing in demand. However, there are still coverage and capacity limitation of wireless links that support such services. In this work, we address a new and novel concept that leverages 4G network for vehicle-to-infrastructure communications. Instead of considering on-board units...
Vast majority of the services running on the smart phone today are networked in that significant amount of communication is required. Smart phone energy expenditure due to Wi-Fi communications constitutes significant portion of the battery discharge. In this paper, we first investigate the key factors influencing Wi-Fi energy consumption, and propose three energy management schemes: 1) Dynamic control...
In this paper we discuss the architecture of MStack, a data-centric communications stack specifically designed for mobile intermittent networking environments. MStack contains native support for delay tolerant connections, it is resilient to disconnections, and solves other problems associated with mobile devices. The architecture and its main protocols are discussed, together with some examples of...
Road maps are important for several applications in vehicular networks. As a consequence, an updated map is essential for a proper behavior of such applications. In this paper, we focus on a map update application based on an infrastructure-to-vehicle communication with a high mobility. In order to understand the application's behavior, we analyze different performance criteria: System Goodput, Packet...
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