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It is heterogeneous wireless Networks (HWN) aggregation foundation for vertical handoff (VHO), and that is key characters of core technology for multi-network aggregation. The currently mechanism handoff trigger is analyzed, a best network selected (BNS) framework is designed, the parameters of network terminal and user terminal of effecting VHO algorithm, and which also include norm of capable parameters,...
Future wireless access will involve a variety of integrated and interworking technologies. Depending on the conditions (e.g., the specific application, the quality of service requirements, the user mobility) each session will be served through the most suited access network; following some event, there will be a variation of the access technology, which is called vertical handover. Although the use...
In this paper, we propose a novel channel selection algorithm for a cognitive radio system that coexists with legacy wireless LAN systems operating in the ISM bands. The cognitive system is capable of scanning its environment to measure ISM channel occupancy in terms of WLAN channel utilization. The system takes the opportunity of spectrum availability to facilitate its communication to the cognitive...
Due to the license-exempt nature of the cognitive radio (CR), multiple CR networks may operate (coexist) on the same channel. In this paper, we first discuss some techniques for self-coexistence of CR local and personal area networks, where the self-coexistence means the coexistence of homogeneous CR networks using the same PHY/MAC protocol. Then, we propose a self-coexistence etiquette for the ECMA...
This paper introduces a technology convergence adaptor for a previously presented Inter-MAC architecture for heterogeneous home area networks. Its main task is to translate technology-dependent link metrics into a machine readable common language. This language allows for the description of various service and application classes and provides means to describe link metrics of underlying MAC protocols...
For ad-hoc home networks without central coordinator, IEEE 802.11 systems merely support service differentiation. In many usage scenarios of a typical home network with applications requiring a strict quality of service (QoS), this MAC functionality is not sufficient. In order to counteract this problem, we developed in previous works a modified MAC scheme based on the IEEE 802.11 enhanced distributed...
The seamless integration of heterogeneous wireless access networks is currently one of the issues of major interest in the field of telecommunication systems. In an early future technologies like UMTS, WLAN and WiMAX will give broadband access to users that perform their voice/video calls or data sessions without knowledge of the specific technology their terminals are using, following the paradigm...
In this paper, we propose a QoS tracking algorithm to support different QoS requirements to accommodate delay-sensitive and throughput-sensitive traffics in wireless mesh networks. The proposed scheme is carried out in a totally distributed manner by adjusting the minimum contention window size. Moreover, we investigate whether we can satisfy all QoS requirements in a stable manner through stability...
The massively growing demand for bandwidth-consuming real-time applications such as voice and video, added to the need of QoS being guaranteed are the main motivation of this work. In this paper we propose a new medium access mechanism that improves the performance of IEEE 802.11e EDCA wireless networks by minimizing the collision probability while maintaining high transmission probability. This was...
IEEE 802.15.4 defines the physical layer and medium access control sub-layer specifications for low-data-rate wireless connectivity devices with very limited battery consumption requirements typically operating in the personal operating space. Unlike traditional wireless networks, its unique characteristics, such as low-data-rate and guaranteed time slots (GTS), have brought unprecedented challenges...
This revision specifies technical corrections and clarifications to IEEE Std 802.11 for wireless local area networks (WLANS) as well as enhancements to the existing medium access control (MAC) and physical layer (PHY) functions. It also incorporates Amendments 1, 2, 3, 4, and 5
Recently, the demanding requirements and use for wireless communication are increased and continue to grow. WiBro is trying to compete with Wi-Fi in coverage and data rate, while the inexpensive Wi-Fi still very popular in both personal and business use. This paper designs and implements Fixed Mobile Convergence (FMC) terminal system supported IEEE802.11 b/g/n Wi-Fi and WiBro. Terminal system of this...
This revision specifies technical corrections and clarifications to IEEE Std 802.11 for wireless local area networks (WLANS) as well as enhancements to the existing medium access control (MAC) and physical layer (PHY) functions. It also incorporates Amendments 1, 2, 3, 4, and 5
This simple and scalable Differentiated Services (DiffServ) QoS control model is acceptable for the core of the network. However, more explicit and stringent admission and reservation based QoS mechanisms are required in the wireless access segment of the network, where available resources are severely limited and the degree of traffic aggregation is not significant, thus rendering the DiffServ principles...
The cognitive radio (CR) based IEEE 802.22 is a standard for wireless regional area networks (WRANs), which is allowed to utilize TV bands when no interference is present to incumbents (i.e. TV receivers and microphones). Compared to other existing networks, it has larger coverage range and provides broadband access in rural and remote areas with performance comparable to DSL and cable modems. It...
This paper presents a comparative analysis, set in Vanet scenarios and based on simulations, between the well-known IEEE 802.11p standard and an efficient slotted protocol based on RR-Aloha (MS-Aloha). Notably the chosen slotted protocol is completely distributed and based on reservation, and has been specifically designed to face issues typical of mobility, while preserving quality of service guarantee...
High concentration of users in a cell of a wireless LAN leads to an unsustainable traffic load at the access point (AP). An unsuitable solution to the problem will cause poor connectivity for users, severe performance degradation, and possible collapse of the wireless LAN. In this paper, we present a scheduler based on queue length at the AP and a congestion control scheme based on the channel utilization...
TCP, the facto standard used in today's Internet, has been found to perform poorly in Mobile Ad Hoc Networks (MANETs). This is exacerbated by contention with increasing UDP-based high priority multimedia traffic and the class differentiation introduced in current QoS protocols, which results into TCP starvation and increased spurious timeouts. In this paper, we propose a cross-layer TCP enhancement...
Services utilizing wireless LANs as communication infrastructure are drawing much attention these days. However, access points (APs) of existing wireless LANs are in most cases connected with wires and it is fairly expensive to install APs. Wireless mesh network is one of the ways to solve this problem. In this paper, we propose a new method to improve the communication quality of wireless mesh network...
HCF controlled channel access (HCCA), defined in the IEEE 802.11e document, provides a sample scheduler to allocate transmission opportunity (TXOP) to QoS-aware stations (QSTAs). Since the calculation of TXOP duration is based on mean data rate, it is efficient for constant bit rate (CBR) traffic. For variable bit rate (VBR) traffic, however, delay bound of some admitted traffic flows may be violated...
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