Energy-efficient wireless communication

In this chapter we present an energy-efficient highly adaptive network interface architecture and a novel data link layer protocol for wireless networks that provides Quality of Service (QoS) support for diverse traffic types. Due to the dynamic nature of wireless networks, adaptations in bandwidth scheduling and error control are necessary to achieve energy efficiency and an acceptable quality of service. In our approach we apply adaptability through all layers of the protocol stack, and provide feedback to the applications. In this way the applications can adapt the data streams, and the network protocols can adapt the communication parameters

Modeling and performance analysis of an alternative to IEEE 802.11e Hybrid Control Function

Modern wireless networks are offering a wide range of applications that require the efficient integration of multimedia and traditional data traffic along with QoS provision. The IEEE 802.11e workgroup has standardized a new QoS enhanced access scheme for wireless LANs, namely Hybrid Control Function (HCF). HCF consists of the Enhanced Distributed Channel Access (EDCA) and the Hybrid Control Channel Access (HCCA) protocols which manage to ensure QoS support. However, they exhibit specific weaknesses that limit network performance. This work analyzes an alternative protocol, called Priority Oriented Adaptive Polling (POAP). POAP is an integrated channel access mechanism, is collision free, it employs priorities to differentiate traffic in a proportional way, it provides fairness, and generally supports QoS for all types of multimedia applications, while efficiently serving background data traffic. POAP is compared to HCF in order to examine the wireless network performance when serving integrated traffic

Priority-Oriented Adaptive Control With QoS Guarantee for Wireless LANs.

In today’s wireless networks there is a great need for QoS, because of the time-bounded voice, audio and video traffic. A new QoS enhanced standard is being standardized by the IEEE 802.11e workgroup. It uses a contention free access mechanism called Hybrid Control Channel Access (HCCA) to guarantee QoS. However, HCCA is not efficient for all types of time-bounded traffic. This work proposes an alternative protocol which could be adapted in HCF (Hybrid Coordination Function). The Priority Oriented Adaptive Control with QoS Guarantee (POAC-QG) is a complete centralized channel access mechanism, it is able to guarantee QoS for all types of multimedia network applications, it enhances the parameterized traffic with priorities, and it supports time division access using slots. Furthermore, it instantly negotiates the quality levels of the traffic streams according to their priorities, supporting multiple streams to the best quality it can achieve. POAC-QG compared to HCCA, provides higher channel utilization, adapts better to the characteristics of the different traffic types, differentiates the traffic streams more efficiently using priorities, and generally exhibits superior performance

QAP: A QoS supportive adaptive polling protocol for wireless LANs

A QoS supportive adaptive polling (QAP) protocol for wireless LANs is introduced. QAP operates under an infrastructure wireless LAN, where an access point (AP) polls the wireless nodes in order to grant them permission to transmit. The polled node sends data directly to the destination node. We consider bursty traffic conditions, under which the protocol operates efficiently. The polling scheme is based on an adaptive algorithm according to which it is most likely that an active node is polled. Also, QAP takes into account packet priorities, so it supports QoS by means of the Highest Priority First packet buffer discipline and the priority distinctive polling scheme. Lastly, the protocol combines efficiency and fairness, since it prohibits a single node to dominate the medium permanently. QAP is compared to the efficient learning automata-based polling (LEAP) protocol, and is shown to have superior performance. © 2005 Elsevier B.V. All rights reserved

A new approach to the, design of MAC Protocols for wireless LANs: Combining QoS guarantee with power saving

An alternative WLAN protocol which could be adapted in the HCF access scheme defined by IEEE 802.11e, in place of the HCCA mechanism, is introduced. LEPOAC-QG (Low Energy Priority Oriented Adaptive Control with QoS Guarantee) is a centralized access mechanism that supports low energy consumption, guarantees QoS for all types of multimedia network applications, enhances the parameterized traffic with priorities, and supports time division access. It instantly negotiates the quality levels of the traffic streams trying to support multiple streams with best possible quality. LEPOAC-QG, compared with HCCA, exhibits generally superior performance

Improving the Performance of Wireless LANs

This book quantifies the key factors of WLAN performance and describes methods for improvement. It provides theoretical background and empirical results for the optimum planning and deployment of indoor WLAN systems, explaining the fundamentals while supplying guidelines for design, modeling, and performance evaluation. It discusses environmental effects on WLAN systems, protocol redesign for routing and MAC, and traffic distribution; examines emerging and future network technologies; and includes radio propagation and site measurements, simulations for various network design scenarios, numerous illustrations, practical examples, and learning aids