Lecture 1: Course Overview

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Southern Methodist University EETS 8315 /
TC752-N Advanced Topics in Wireless
Communications Spring2005 http//engr.smu.edu/eets
/8315 Lecture 11 WIMAX Instructor Dr. Hossam
Hmimy, Ericsson Inc. hossam.hmimy_at_engr.smu.edu (9
72) 583-0155
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Announcement
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WiMAX forum

• The WiMAX mission is to make the 802.16
  interoperable. Just like WiFi did for 802.11.
• No WiMAX compliant products today, foreseen
  during 2005. The first WiMAX products will be
  based on 802.16d.
• Intel is the most powerful player in WiMAX forum
• Architecture specification work initiated in a
  new sub-group

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WiMAX forum ..

• FDD as well as TDD
• Licensed as well as unlicensed spectrum
• Licensed needed to guarantee wide area service
• No single global spectrum assigned, possibilites
• 5.8 GHz
• 3.5 GHz
• 2.5 GHz, (IMT-2000 more likely in this band)
• 2.3 GHz

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38 of US households are interested in a Portable
Broadband Service...
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Broadband Technologies
3G Evolved
802.16
DSL/Fiber

• Fixed
• Triple Play (Video)
• IP Telephony
• Internet

• Fixed
• Nomadic
• IP Telephony
• Internet

• Full mobility
• Full roaming
• All over the world
• POMS
• IP Telephony
• Internet

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WiMAX Standards Roadmap
WiMAX interoperable subset of this (lt 6 GHz)
Some Mobility 2005 ?
802.16e
2 11 GHz NLOS Jan 2003
802.16a
802.16
10 66 GHz LOS Sep 2000
NOTE IEEE 802.16 specifies only layer 1 2
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802.16 for Broadband Wireless Access

• DSL complement
• DSL is not available, e.g. poor copper
  infrastructure
• DSL OPEX too high, e.g. low population density
• Central Office is too far away for DSL
• CLEC bypassing incumbent
• DSL competition
• If DSL is available, hard to beat

802.16
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WiMAX segments, High level pros and cons

• Backhaul, Fixed, point to point LOS
• High Bitrate
• Low Interference
• Clear Signal No multipath fading
• Relatively Low Cost
• DSL, Fixed up to portable, Point to point, point
  to multipoint NLOS
• Relative high bitrate, but lower
• One cell
• Still relative cheap
• Low to moderate interference-gt Static radio
  environment
• WAN and Mobile environment
• Significantly lower bitrate
• High interference. More multipath fading and
  dopplershift effects

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IEEE 802.16 Standard
WiMAX
802.16 802.16d/HiperMAN 802.16e
Completed December 2001 June 2004 (802.16d) Estimate 2005
Spectrum 10 - 66 GHz lt 11 GHz lt 6 GHz
Channel Conditions Line of Sight Only Non Line of Sight Non Line of Sight
Bit Rate 32 134 Mbps in 28MHz channel bandwidth Up to 75 Mbps in 20MHz channel bandwidth Up to 15 Mbps in 5MHz channel bandwidth
Modulation QPSK, 16QAM and 64QAM OFDM 256 FFT QPSK, 16QAM, 64QAM Scalable OFDMA 128 to 2048 FFT
Mobility Fixed Fixed Portable
Channel Bandwidths 20, 25 and 28 MHz 1.75 to 20 MHz 1.75 to 20 MHz
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WIMAX Features
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WiMAX Modulation and Coding
The further the subscriber is from the base
station, the greater the likelihood of a lower
form of modulation and a higher amount of coding
and thus a lower bit-rate
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Fit with Other Technologies

• Whether 802.16a will complement or clash with
  certain other technologies remains to be seen.
  For a while, at least, it will certainly be
  complementary to 802.11a, enabling Wi-Fi users to
  dramatically extend their distance from wired
  networks.

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Theoretical WiMAX Raw Bandwidth (Mbit/s)
OFDM 256 FFT. Includes MAC and preamble overhead
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Theoretical Coverage (Km)
Type of Area
Rooftop Antenna
Window/Fixed Antenna
Indoor/Portable Antenna
lt20 Km using NLOS
Rural
lt8 Km
lt4 Km
Suburban
lt4 Km
lt2 Km
N/A
Urban
N/A
lt2 Km
lt1 Km
Approximate distances only, depends heavily on
geographical area
lt50 Km is the theoretical maximum for LOS.
Assumption is a NLOS base station and a rooftop
antenna for better reception and maximum uplink
power
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Portability (Mobility) in 802.16e

• New network reference model
• New BS-BS interface (IB) and BS-server interface
  (A) defined
• Authentication and service authorization (ASA)
  servers provide authorization, authentication,
  billing, management, provisioning and other
  services. EAP is defined for SIM cards, and other
  means of Authentication.

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Enhancements for mobility in 802.16e Layer 2

• Handover (HO) process defined in MAC including
• cell reselection
• target BS scanning
• network re-entry
• HO decision and initiation and HO cancellation.
• MAC messages for each of the handover functions
  defined.
• Broadcast paging message defined.
• Neighbor topology advertisement messages defined.
• Option of using mobile IP provided. To be defined
  in May-05. WG active.
• Full QoS supported. All four GSM/WCDMA classes.

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Enhancements for mobility in 802.16e Layer 1

• Sleep mode, paging enabled.
• Fast time alignment (ranging) mechanism
• Flexible FFT sizes depending on channel bandwidth
  to ensure OFDM symbol duration is compatible with
  mobility requirements
• Soft handover, i.e., transmit/receive from
  multiple BS
• Fast channel feedback
• Fast BSS handover involving maintenance of sync
  to multiple BS while transmitting/receiving from
  anchor BS
• New MIMO, STC modes
• MIMO soft-handoff based macro-diversity
  transmission
• Space-time codes for 3 antenna configurations.
  Fixed version has 2 and 4 antenna modes.

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some differences

• MAC
• 802.11 Contention-based MAC (CSMA/CA), basically
  wireless Ethernet.
• 802.16 Dynamic TDMA-based MAC with on-demand
  bandwidth allocation.
• OFDM
• 802.11a 64 FTTs
• 802.16d 256 FFTs
• Spectrum
• 802.11 limited channels in Un-license spectrum
• 802.16 multiple channels in licensed
  Un-license spectrum

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Comparison 802.11 and 802.16
802.11 lt 300 feet Optimized for indoor short
range 2.7 bps/Hz peak. lt 54Mbps in 20MHz
1-10 CPE CSMA/CA No QOS
Technology Range Coverage Data
rate Scalability QOS
802.16 lt 30 Mile ( typical 34) Outdoor LOS
NLOS 5bps/Hz peak, lt100Mbps in 20 MHz 1-
hundreds CPE TDMA On demand BW ? voice Video,
data
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Broadband Wireless systems

• WiMAX
• Wireless Broadband
• Laptop centric
• Fixed ? Portability
• Line-of-Sight Non Line-of-Sight
• IEEE Layer 1 2 standard
• Data optimized
• Optimized for Fixed High data rate
• Evolution towards mobility
• Drivers
• Data optimized network (simple)
• DSL complement

• 3G Evolved
• Mobile Broadband
• Phone laptop
• Full mobility
• Non line-of-sight
• 3GPP and 3GPP2 standard
• Voice/data optimized
• Optimized for Mobility
• Evolution towards Higher Data
• Drivers
• Mobile Broadband for incremental investment
• National global roaming networks

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Peak Bit Rates Comparison
Channel Bandwidth
Peak bit-rate DL
Peak Bit-rate UL
FDD/TDD
Standards compliant
GSM/GPRS
3GPP
160 kbps
160 kbps
FDD
200KHz
EDGE
480 kbps
480 kbps
FDD
3GPP
WCDMA
2 Mbps
2 Mbps
FDD/TDD
3GPP
5Mhz
HSDPA
14.4 Mbps
7.68 Mbps
FDD
3GPP
CDMA2000 1x
640 kbps
450 kbps
FDD
3GPP2
1xEV-DO
1.25 MHz
3.1 Mbps
1.8 Mbps
FDD
3GPP2
1xEV-DV
3.1 Mbps
1.8 Mbps
FDD
3GPP2
IEEE 802.16d
-20 MHz
- 75 Mbps
- 75 Mbps
FDD/TDD
IEEE
_
Flarion
FDD
1.25 MHz
3.2 Mbps
900 kbps
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User data rates
WCDMA CDMA2000 Flash-OFDM WCDMA Release
99 1xEV-DO (Proprietary) Evolved (HSDPA)
Peak data rateaccording to Specification(Mbps)
Average data rate in the Field(Mbps)
2.0
2.5 - 3.1
3.0
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0.3
0.3-0.6
0.3-0.6
2 - 4
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• Propagation difference between 1900MHz and other
  frequencies ( H-O Model)
• 2100MHz ( Delta 1.1dB)
• 2400MHz ( Delta 2.6dB)
• 3500MHz ( Delta 7dB)
• 850 MHz ( Delta -12 dB)

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WiMax IEEE802.16a, e

• Understanding WiMax
• http//www.intel.com/netcomms/technologies/downloa
  ds/305150.pdf
• http//www.intel.com/netcomms/technologies/wimax/3
  04471.pdf
• http//www.wimaxforum.org/certification/White_Pape
  rs/
• OFDM
• http//www.intel.com/netcomms/technologies/wimax/3
  03787.pdf
• Adaptive modulation
• http//www.intel.com/netcomms/technologies/wimax/3
  03788.pdf