Broadband Wireless Access:
A Brief Introduction to
IEEE 802.16 and WiMAX
Prof. Dave Michelson
[email protected]
UBC Radio Science Lab
26 April 2006
1
Introduction
• The IEEE 802.16/WiMAX standard promises to
revolutionize wireless delivery of broadband services:
– an alternative to DSL and cable modems
– backhaul for access points and base stations
– long-range connections for private networks
• With standards, development, and certification welladvanced, the next major challenge is deployment.
• Now is a good time for wireless professionals to
become familiar with WiMAX wireless technology
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Introduction - 2
• What is IEEE 802.16/WiMAX?
– a wide area alternative to IEEE 802.11/WiFi?
– a threat to cellular telephony (voice and data)?
– a method for breaking wireline monopolies?
– a method for providing backhaul to IEEE
802.11/WiFi access points?
– a single standard or a family of standards?
– a universal solution for broadband wireless access?
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Introduction - 3
• How is IEEE 802.16/WiMAX different from (or better
than) other wide area wireless standards?
– use of OFDM with provision for OFDMA and
MIMO?
– support for a wide range of channel bandwidths
(and, as a result, performance levels)?
– implementation of differentiated QoS?
– support for multiple usage models?
– use of system profiles to manage design options?
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Objective
This presentation introduces IEEE 802.16/WiMAX by:
1. Briefly reviewing its history
2. Summarizing its key features (and the key
players)
3. Reviewing alternative use cases and deployment
scenarios
4. Suggesting sources of additional information
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1. A Brief History of IEEE 802.16/WiMAX
• In the mid-1990’s, various groups began to promote
“last-mile” fixed wireless access solutions.
• Multiple goals:
– Provide the capacity and reliability of wireline
but with the flexibility and ease of deployment
of wireless
– Provide a versatile system for corporate or
institutional backhaul/distribution networks
– Break the monopolies of incumbent carriers
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A Brief History of IEEE 802.16/WiMAX - 2
Interest soon focused in two approaches.
• LMDS (in Canada, LMCS)
– operates in mm-wave spectrum under LoS conditions
– uses conventional QAM modulation with ATMderived upper layers to provide high speed service
• MMDS (and other nearby bands)
– operates near 2 GHz, usually under LoS conditions
– may use any of various PHY, MAC, and NET layers
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A Brief History of IEEE 802.16 and WiMAX - 3
• High costs, lack of standards and fear of vendor
lock-in drove off potential LMDS customers.
• In 1999, IEEE 802.16 was formed to address these
issues by developing open standards for LMDS.
• In 2001, the IEEE 802.16 standard for BWA systems
operating in the 10-66 GHz range was released!
• Since then, however, interest has shifted to a new
version of the IEEE 802.16 standard for BWA
systems operating in the range 2-11 GHz
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A Brief History of IEEE 802.16 and WiMAX - 4
• Early BWA concepts were based on early WLAN
technology and had limited capability.
• In the mid-1990’s, AT&T developed a proprietary
“last-mile” access solution (Project Angel) that:
– operated near 2 GHz under either LoS or NLoS
conditions
– used OFDM and other advanced concepts
– delivered high capacity, throughput, and QoS.
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A Brief History of IEEE 802.16 and WiMAX - 5
• By the late 1990’s, many other manufacturers began
to pursue development of similar products.
• In response, IEEE 802.16 formed a subgroup to
extend the LMDS standard to the range 2-11 GHz.
• Our work at AT&T led to the propagation and
channel models adopted by IEEE 802.16.
• IEEE 802.16a was published in 2003.
• IEEE 802.16a/b/c and various updates were
incorporated into IEEE 802.16-2004.
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A Brief History of IEEE 802.16 and WiMAX - 6
• IEEE 802.16e seeks to provide the additional
features required to serve mobility users.
• Use of Scalable OFDMA, MIMO, etc. permits 63
Mbps DL and 28 Mbps UL in a 10 MHz channel.
• Optimized handover ensures latency < 50 ms.
• Flexible key management ensures security.
• South Korea’s WiBro is based upon IEEE 802.16e.
• IEEE 802.16e was ratified in December 2005
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A Brief History of IEEE 802.16 and WiMAX - 7
• IEEE 802.16’s approach is being used by many other
groups including IEEE 802.20, 802.22, 3GPP - LT
• For example, IEEE 802.20 (Mobile Broadband
Wireless Access) was established on 11 Dec 2002.
• Aim – specify an air interface designed for IP-based
services operating in bands below 3.5 GHz with peak
data rates of over 1 Mbit/s.
• A draft IEEE 802.20 specification was balloted and
approved on 18 Jan 2006.
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A Brief History of IEEE 802.16 and WiMAX - 8
• In 2001, the WiMAX Forum was formed to address
issues beyond standards development, e.g.,
– marketing and promotion
– development of system profiles
– development of certification procedures
– government lobbying
• In January 2005, the WiMAX Forum selected
Cetecom Spain as its official certification laboratory.
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A Brief History of IEEE 802.16 and WiMAX - 9
• Many pre-WiMAX and WiMAX networks have been
trialed and deployed in recent months.
• Pre-WiMAX has several meanings:
– compliant but not yet certified
– compliance is possible after a firmware upgrade
– mostly compliant, but not completely
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A Brief History of IEEE 802.16 and WiMAX - 10
The WiMAX Value Chain
•
•
•
•
•
•
•
IEEE 802.16 – Standards Working Group
WiMAX forum – Industry Advocacy Group
Chip Vendors
• Certification Labs
Equipment Vendors
• Consultants
System Integrators/VARs
• Information Providers
Carriers/Service Providers
End Users
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2. Key Features of WiMAX
• Major goal of IEEE 802.16 (2-11 GHz): provide a
“universal” solution for broadband wireless access
– point-to-multipoint, LoS or NLoS
– ranges of “several” km; urban, suburban, rural
• Problem: Can one size really fit all? Different
applications have different requirements and
constraints for spectrum and performance!
• Solution: Allow choice of options within a consistent
framework. Offer a limited set of standard profiles.
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Key Features of WiMAX - 2
•
•
•
•
Operating Frequency: 2 – 11 GHz***
Allocations: Licenced and Unlicenced**
Channel Bandwidth: 1.25 – 20 MHz
Modulation: Single carrier*, 256 OFDM, 2048 OFDMA
– BPSK*, QPSK, 16-QAM, 64-QAM, 256-QAM*
• Antenna system support: Diversity, MIMO, SDMA
• Duplexing: FDD, H-FDD, TDD**
• Data Rates: From T1 (1.5 MB/s) to over 70 Mb/s
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Key Features of WiMAX - 3
• WiMAX supports flexible frequency allocation and
use of system profiles
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Key Features of WiMAX - 4
52 carriers,
312.5 kHz
spacing
4 BPSK Pilots
BPSK, QPSK, 16QAM, 64QAM
802.11a (18 MHz)
200 carriers,
90 kHz
spacing
.
8 BPSK Pilots
BPSK, QPSK, 16QAM, 64QAM
.
.
200 carriers,
6.7 kHz
spacing
.
.
.
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802.16 (20 MHz)
:
10 MHz
7.0 MHz
3.5 MHz
:
1.5 MHz
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Key Features of WiMAX - 5
• An estimate of the maximum data rate of a WiMAX
system operating in the 5 GHz band using OFDM
• System parameters
– BW = 20 MHz
– SCM = 64-QAM (1 symbol = 6 bits)
– No. of data subcarriers = 192
– Raw data rate = 100 Mb/s
– After accounting for coding/MAC/TDD overhead,
the effective data rate is closer to 70 Mb/s
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Key Features of WiMAX - 6
The IEEE 802.16 MAC layer supports
• OFDM and OFDMA
• ARQ (Automatic Repeat Request)
• Dynamic Frequency Selection
• Mesh Networking
• Advanced Antenna Systems
• Differentiated Quality of Service
• Enhanced Security
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3. Key Deployment Scenarios
•
•
•
•
•
•
Links from carriers to major customers
Backhaul for access points and cellular base stations
Long-range connections for private networks
Supervisory control and data acquisition
An alternative to DSL and cable modems
An alternative to cellular data services
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4. Our Research Interest in Fixed Wireless
• As systems move to higher frequencies, are deployed in
more challenging environments, or become more
complex, models must be updated and extended
• Past work has shown that the fixed wireless channel can
range be extremely harsh.
Transmitted Signal
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Our Research Interest in Fixed Wireless - 2
• Existing channel models do not completely capture the
dynamics of fixed wireless channels
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Our Research Interest in Fixed Wireless - 3
• Fixed wireless channel dynamics is concerned with the
measurement and simulation of the time-varying
properties of the channel over the long and short-term.
• Issues include:
– physical-statistical description of the channel,
– effect of alternative antenna configurations,
– development of impairment mitigation strategies,
– development of more effective radio resource
management schemes.
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Our Research Interest in Fixed Wireless - 3
• Current Sponsors
• Graduate Students:
– Joy Zhang, Jin Ng, Howard Huang, Anthony Liou
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5. Probing Further
• IEEE 802.16 - www.ieee802.org/16/
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Probing Further - 2
• WiMAX Forum - www.wimaxforum.org
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Probing Further - 3
• WiMAX @ Intel - www.intel.com/go/wimax
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Probing Further - 4
• Other industry portals, e.g.,
– www.wimaxpro.com
– www.wimax-industry.com
– www.wimax.com
• Booksellers, e.g.,
– www.chaptersindigo.ca
– www.amazon.ca
• WiMAX conferences
• Vendors (white papers, etc.)
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Summary
• IEEE 802.16/WiMAX broadband wireless access
supports:
– channel bandwidths between 1.5 and 20MHz
– data rates ranging from 1.5Mbps to over 70Mbps
– the available spectrum and channel widths in
different countries or licensed to different providers
– advanced quality-of-service features that ensure
high performance for data, voice and video
– system profiles that permit a certain degree of
customization within the IEEE 802.16 framework
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Summary - 2
• The IEEE 802.16/WiMAX community has already
achieved several significant milestones:
– the IEEE 802.16 standard has been released and
refined.
– the WiMAX forum is addressing the needs of
industry for promotion, certification, etc.
– vendors have developed silicon and equipment.
• As rollout begins, operators will begin addressing
issues that arise during deployment and operation.
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Summary - 3
What will it take for WiMAX to be successful?
• Equipment must perform as advertised:
– Coverage, reliability, and interoperability
– Quality of service, throughput and capacity
• Deployment must be straightforward; design rules
should reduce the need for network tuning
• WiMAX must return value (e.g., performance/cost)
that is an order of magnitude higher than existing
technology can.
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Next….
• Andrew Tsui (Bell Canada) will describe one of the
largest pre-WiMAX rollouts to date
• Angela Choi (Industry Canada) will summarize
spectrum allocation and regulatory issues
After a break…
• Ben Zarlingo (Agilent Technologies) will describe
WiMAX test and measurement solutions
• Angela Ikemoto and Michael Fite (Agilent) will
demonstrate measurement of actual WiMAX signals
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