An Analysis of the Design and Implementation of QoS over IEEE 802.16 file:///X:/www-docs/cse574-06/ftp/wimax_qos/index.html1 of 18 5/9/2006 6:56 PMAn Analysis of the Design and Implementation of QoS over IEEE 802.16Mark C. WoodAbstractThis paper gives an overview of the QoS mechanisms built into the IEEE 802.16 standard (also known by thename of its vendor interoperability organization, WiMAX). The PHY and MAC layers of 802.16 are described in detail with regards to their QoS aspects. And the relations and interactions of these QoS mechanisms are described to give an understanding of how QoS can be achieved over 802.16. This paper willalso provide some factors that make 802.16 distinct in its QoS methods. A comparison of the QoS mechanisms in competing technologies (i.e. 802.11, 3G) will be given. Also, this paper will explore some of the current research being done with 802.16 on developing its QoS performance. Keywords: IEEE 802.16, WiMAX, QoS, BWA, WMAN, WirelessMAN, multimedia networkingTable of Contents1.0 Introduction1.1 Background1.2 IEEE 802.16 History and Future Potential2.0 IEEE 802.16 QoS - General2.1 The Need for QoS2.2 IEEE 802.16 QoS Mechanisms2.3 Adaptive Burst Profiles3.0 IEEE 802.16 QoS Provisioning3.1 Service Flow Classification3.2 Dynamic Service Establishment3.3 Two-Phase Activation Model4.0 IEEE 802.16 MAC Layer5.0 Bandwidth Requests and Grants5.1 Bandwidth Requests5.2 Bandwidth Grants6.0 Comparison with Competitor’s QoS6.1 IEEE 802.116.2 3G6.3 Advantages of QoS over IEEE 802.167.0 Suggestions for Improvement8.0 SummaryReferencesList of Acronyms1.0 IntroductionAn Analysis of the Design and Implementation of QoS over IEEE 802.16 file:///X:/www-docs/cse574-06/ftp/wimax_qos/index.html2 of 18 5/9/2006 6:56 PM1.1 BackgroundWireless networking has the potential for use in broadband Internet services, video and audio streaming, andas an alternative to the PSTN for voice service. WiMAX phones and PDAs are already being developed bycompanies like Motorola and Samsung. And, they are already in use in Korea, with WiMAX’s cousintechnology, WiBro. Soon WiMAX adapters will be built into most laptops. You will not have trouble findinga hot spot. With WiMAX coverage, everywhere will be hot. There has been some struggle to popularize Broadband Wireless Access (BWA). Most of the delays in theuse of BWA up to this point have been caused by legal or political obstructions in the US. Wireless technology is being introduced rapidly in places like China and India that lack the copper wire and fiber cable infrastructures. However, there have been some legitimate concerns over the use of wireless in broadband networking from atechnical standpoint. Some of the primary concerns have been packet loss, atmospheric interference, and contention with other wireless services. The 802.16 standard addresses these concerns with QoS. In short, applying more bandwidth to the right channels at the right time can reduce latency and jitter [Ohrtman05]. 1.2 IEEE 802.16 History and Future PotentialThe IEEE 802.16 standard, which includes MAC and PHY layer specifications, was developed for Internetservices over wireless metropolitan area networks (WMANS), and as an alternative to traditional wired networks, such as DSL and cable-modem. 802.16 has two modes: point-to-multipoint (PMP) mode and mesh mode [Cao05]. One of things that distinguishes 802.16 in the PHY layer is Orthogonal Frequency Division Multiplexing(OFDM), which is a multicarrier modulation scheme. The 802.16 standard has two OFDM-based modes: OFDM and Orthogonal Frequency Division Multiplexing Access (OFDMA). Both of these technologies allow subcarriers to be adaptively modulated (QPSK, 16-QAM, 64-QAM), depending on distance and noise. OFDMA also has scalability options that provide higher efficiency in bandwidth use [Intel04]. The MAC layer of 802.16 was originally designed for point-to-multipoint (PMP) broadband wireless accessapplications, but later amendments of 802.16a and 802.16d also allow for mesh network architecture [Ghosh05]. And, newly adopted in 802.16a was OFDM, which provides greater spectral efficiency and bettermitigation of interference. 802.16b covers most of the QoS aspects of the standard. 802.16TGe introduced scalable OFDMA into the standard. 802.16-2004 revised and replaced previous versions and completed the essential fixed wireless standard. And 802.16e was an enhancement for supporting mobile communications; ahandoff mechanism was added, making it possible to support mobile communications at vehicular speeds. A summary of the history of the 802.16 standard, with regard to the QoS aspects of it, is shown in Table 1.An Analysis of the Design and Implementation of QoS over IEEE 802.16 file:///X:/www-docs/cse574-06/ftp/wimax_qos/index.html3 of 18 5/9/2006 6:56 PMTable 1: History of IEEE 802.16 standards, QoS aspectsThe WiMAX forum (http://www.wimaxforum.org/home) was formed in June of 2001 to ensureinteroperability among products by different vendors. And the IEEE 802.16 Working Group on BroadbandWireless Access Standards (www.wirelessman.org/) is the group developing the IEEE 802.16 WirelessMANStandard for WMANs. These groups, and a few others, may help popularize WiMAX by bringing vendorstogether on it. As Vint Cerf, TCP/IP co-developer and Internet pioneer, said “People often take the view thatstandardization is the enemy of creativity. But I think that standards help make creativity possible -- byallowing for the establishment of an infrastructure, which then leads to enormous entrepreneurialism,creativity, and competitiveness.” [Fast Company, April 2000] A separate technology known as softswitch offers a technology bypass of the PSTN switches. And, 802.16has a non line-of-site (NLOS) range of 4 miles. The combination of softswitch and 802.16 as a wireless “lastmile” makes a viable alternative to the PSTN for voice services. With another technology known as TVoIP,802.16 can also serve as a cable or satellite TV bypass. And, with the 802.16 standard’s ability to transmit 72Mbps over 30 miles point-to-point, it can also serve as a backhaul bypass. A strong business case can bemade for using WiMAX as an alternative to the telephone company’s T1 and DS3 data circuits to save theenterprise the monthly local loop charges [Ohrtman05]. And the combination of throughput, power, range and versatility give 802.16 some technological advantages over competing technologies, such as 802.11 and 3G. There are a
View Full Document
Unlocking...