Similarities and Differences between LTE, UMB & WiMax

1
Similarities and Differences between LTE, UMB
WiMax

• Presented By Brandt Elster

2
Outline

• WiMax News
• Definitions
• Background History
• Motivations and Objectives
• Deterrents
• Services and QoS
• Network Architecture
• Physical Layer MAC Protocols
• Comparison of the Technologies
• Future of the Technology

3
WiMax News Today

• Today there was a large announcement regarding
  the future of mobile WiMax
• Since Dan Hesse became the new Sprint CEO there
  were doubts he would continue Sprints future in
  their WiMax venture named XOHM.
• Immediately upon becoming CEO he terminated an
  existing agreement to work along side Clearwire
  and collaborate on separate WiMax networks that
  were able to roam on each others to increase
  coverage
• Today Sprint and Clearwire put out a joint press
  release stating they had formed a joint venture
  that would be named Clearwire to build one WiMax
  network.
• This new company has received investments from
  the following companies Google, Intel, Comcast,
  Time Warner Cable, and Bright House networks
• These companies have combined together for a
  total investment of 3.2 billion
• They will receive an estimated 22 ownership of
  the company
• Sprint will maintain the largest share at 51 and
  Clearwire will control 27
• The deal is estimated to be worth a total of
  14.5 billion

4
Definitions - LTE

• Long Term Evolution is more commonly referred to
  as LTE
• LTE is the 4th generation network that was
  designed through the Third Generation Partnership
  Project (3GPP).
• It is an all IP network
• Its primary goals were to improve efficiency,
  lower infrastructure costs, create a higher QoS,
  all while making use of new spectrum
  opportunities, and better integrating with other
  open standards
• Predominantly created by Ericsson, Nortel and
  Nokia-Siemens
• Should result in release 8 of the UMTS standard

5
Definitions - UMB

• Ultra Mobile Broadband is commonly referred to as
  UMB
• UMB is the 4th Generation wireless broadband
  access network developed through the CDMA
  Development Group (CDG)
• It is an all IP network
• It was designed from the ground up to provide the
  type of access required in the modern mobile
  world, with great flexibility and
  interoperability
• Standardized by the 3rd Generation Partnership
  Project 2 (3GPP2)
• Proprietary technology developed by Qualcomm

6
Definitions - WiMax

• Mobile WiMax is short for Wireless
  Interoperability for Microwave Access
• There is actually a difference between mobile
  WiMax and fixed WiMax
• Today we are only going to talk about the mobile
  version of WiMax
• WiMax is the 4th Generation wireless broadband
  access network developed by the IEEE
• It is the 802.16e or upcoming 802.16m standards
• It is an all IP network
• Many hardware manufacturers are already
  supporting WiMax due to its open standards.
  Some of the larger ones include Samsung, Motorola
  and Intel.

7
Background History

• Analogy for the differences between TDMA, FDMA,
  SDMA, CDMA
• Take a large room with a decent number of people
  in it. There are multiple different
  conversations going on throughout the room.
• TDMA Everyone in the room would take turns
  speaking. Each group of people would be assigned
  a specific time slot.
• FDMA Each group in the room would speak at a
  different pitch (frequency) far enough apart that
  they can be differentiated.
• SDMA Each groups speaker would talk in a
  specific direction, only people in front of them
  would be able to hear. If the room is big enough
  you could have multiple people speaking in the
  same direction as long as they were far enough
  apart.
• CDMA Each group would be assigned a specific
  language to communicate with. They would be able
  to easily discern their specific language and all
  others would be small and ignorable background
  noise.

8
Background History

• OFDMA
• Basically an enhanced version of FDMA
• Allows for the elimination of guard bands by
  using orthogonal signals.
• Signals are considered to be orthogonal if their
  dot products are equal to 0
• Signals are able to overlap without causing
  interference to the other
• Signals are modulated and demodulated using the
  Fast Fourier Transform
• SC-OFDM
• This is a single carrier equivalent of OFDMA
• Each transmission is given only one carrier
• This allows the peak-to-average power to be lower
  thus increasing the capable average power of the
  power amplifier
• This is helpful because the user terminal is
  generally battery powered and this includes both
  battery life and range

9
Background History - LTE

• Part of the 3GPP standard
• Essentially it is HSPA rev 8
• It was given the name Long Term Evolution by the
  3GPP
• The name follows their generally naming scheme.
  They try to make their name represent their
  monopoly over the wireless arena
• GSM stands for Global Standard for Mobile UMTS
  stands for Universal Mobile Telephone Standard
• Originally started as GSM
• Capable of virtually no data communications
• Pioneered the first short messaging service (SMS)
• Supports handoffs with all UMTS and GSM networks
• There is discussion to build in the ability to
  support handoffs with CDMA networks

10
Background History - LTE

• GSM was the 2G technology that both GPRS and EDGE
  are based on
• GPRS was the first step
• Stands for General Packet Radio Service
• It is considered to be a 2.5G
• Capable of speeds from 56 up to 114 kbit/s
• Supports a very robust voice channel and low
  bandwidth data options.
• Main data use was text internet downloading of
  reduced size pictures and music

11
Background History - LTE

• EDGE was the next step
• Stands for Enhanced Data rates for GSM Evolution
• It is considered to be a 2.75G
• Capable of speeds from 1 Mbit/s
• Reduced latency to 100 ms
• However just like GPRS, the main data use was
  text internet downloading of reduced size
  pictures and music

12
Background History - LTE

• Following EDGE came UMTS
• Stands for Universal Mobile Telephone Standard
• UMTS was the first truly 3G technology to come
  from 3GPP
• UMTS is a completely different technology than
  GSM.
• It required a completely new network be built
  over the top of any existing networks
• UMTS uses W-CDMA instead of the TMDA that powered
  GSM
• The primary difference between W-CDMA and
  CDMA2000 is that W-CDMA uses 5 MHz blocks of
  spectrum and CDMA2000 uses only 1.25 MHz blocks,
  hence where the wide came from
• The first revision of UMTS was capable of speeds
  up to 2 MB/s

13
Background History - LTE

• HSPA was the final step for W-CDMA
• HSPA stands for High Speed Packet Access
• There are three different enhancements to HSPA,
  HSDPA, HSUPA and HSOPA
• HSDPA stands for High Speed Downlink Packet
  Access
• It predominantly increases the download speed of
  the network.
• HSUPA stands for High Speed Uplink Packet Access
• It predominantly increases the upload speed of
  the network
• HSOPA stands for High Speed OFDM Packet Access
• This technology replaces the entire
  infrastructure of UMTS and replaces it with a new
  OFDM infrastructure
• It is a separate technology from LTE but is part
  of the overall picture. Most likely it will
  never be implemented but its technologies will
  be morphed into LTE

14
Background History - LTE

• Table of different UMTS Technologies and their
  specifications

15
Background History - UMB

• Part of the CDMA 2000 standard
• First named EV-DO rev C
• Renamed to Ultra Mobile Broadband by the CDMA
  Development Group (CDG)
• Originally started as cdmaOne
• A 2G Qualcomm technology
• Capable of virtually no data communications
• Will be capable of call handoffs with all legacy
  CDMA2000 networks

16
Background History - UMB

• cdmaOne was the 2G technology that both 1xRTT,
  1xEV-DO, and 1xEV-DV are based on
• 1xRTT was the first step
• It is considered to be a 2.5G
• Capable of speeds up to 144 kbit/s
• Also referred to as just 1x
• Supports a very robust voice channel and low
  bandwidth data options.
• Main data use was text internet downloading of
  reduced size pictures and music

17
Background History - UMB

• The next step was 1xEV-DO (Evolution Data Only)
• Later renamed Evolution Data Optimized to remove
  the negative connotation
• Most commonly referred to as just EVDO, or simply
  EV
• First truly 3G technology and first real wireless
  broadband technology.
• An alternative to EVDO was 1xEV-DV (Evolution
  Data Voice)
• The standard was not completed in time so it was
  ultimately passed up
• Theoretical speeds of 3.1 Mbit/s downlink and 1.8
  Mbit/s uplink.

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Background History - UMB

• EVDO began as Rel 0.
• Significant speed improvements over 1x
• 2.4 Mbit/s downlink
• 153 kbps uplink
• Includes the following protocols and more
• Hybrid ARQ
• Incremental Redundancy Feedback in the Downlink
• Downlink and Uplink Rate Controls

• Supports the following applications
• broadband Internet
• MP3 music downloads
• 3D gaming
• TV broadcasts
• Video and audio downloads

19
Background History - UMB

• The current and most up to date standard of the
  CDMA2000 protocol is EVDO Rev A
• It is currently being deployed over Rel 0
• Capable of producing speeds of 3.1 Mbit/s
  downlink and 1.8 Mbit/s uplink
• Uses enhanced access channel MAC
• Controls who sends and who receives and when
• Advanced QoS support
• Increased spectral efficiency
• 1.2 times Rel 0 forward link sector capacity and
  3.4 times reverse link sector capacity
• Low latency, below 50 ms
• Supports all the services of Rel 0 but adds
  higher quality video and faster loading times for
  streaming services

20
Background History - UMB

• Rev B would be the next upgrade
• It is likely to be skipped for Rev C in 2009
  similar to how EVDV was bypassed
• Speeds of up to 14.7 Mbit/s downlink
• Utilizes statistical multiplexing
• Hybrid frequency reuse
• Supports OFDM
• Adds multi carrier support
• Rev A uses 1.25 MHz carriers, most likely 3 per
  user would be used for Rev B, or 3.75 MHz
• This is unique from HSPA because the carriers do
  not need to be adjacent
• This allows operators to combine spectrum from
  multiple blocks
• Adds the ability to do High Definition video
  streaming, multiplayer online gaming, and
  replacement of home HSI and hotspots

21
Background History - WiMax

• It evolved from the WiFi standards in an effort
  to create a technology that could cover a larger
  footprint.
• Example, if WiMax is a cell phone, then WiFi
  would be a cordless phone.
• Fixed WiMax was designed as a technology that
  could be used to blanket a city with mobile
  internet to replace building costly short range
  WiFi networks.
• Mobile WiMax took the same technology and evolved
  it into version that could work with devices that
  are no longer stationary
• WiMax comes from the IEEE 802 set of standards.
• The IEE 802 standards are a family of standards
  that deal with Local Area Networks (LANs) and
  Metropolitan Area Networks (MANs)
• WiMax is the 802.16 standard.

22
Background History - WiMax

• History of the IEEE 802 standard
• IEEE 802.3 is collection of IEEE standards that
  define the Media Access Control Layer, Physical
  Layer and Data Link Layer of the wired Ethernet
  standard
• IEEE 802.11 is Wireless LAN Mesh a.k.a. WiFi
• It is a group of standards for wireless local
  area networks (WLAN)
• These typically operate in unlicensed spectrum
  bands located near 2.4 GHz and 5 GHz.
• Maximum range of WiFi is roughly 70m indoors
  using the 802.11n standard and is capable of
  producing 74 Mbit/s
• IEEE 802.15 is Wireless Person Area Networks
  (PAN)
• This standard includes Bluetooth and ZigBee

23
Background History - WiMax

• Brief Discussion of 802.11 Wifi
• Wifi is predominantly used in the 2.4 GHz range
  due to range limitations with the 5GHz frequency
  band
• It divides these frequency bands into channels
  that are 22 MHz wide with 5 MHz spacing in
  between.
• WiFi networks consist of two main components.
  The Access Points (APs) and the clients. The AP
  continuously broadcasts its SSID or name every
  100 ms at 1 Mb/s. Sending at 1 Mb/s ensures that
  all users are at least capable of sending at that
  speed.
• WiFi is not capable of collision detection. It
  instead does collision avoidance using RTS/CTS.
  It also uses acknowledgements to make sure that
  the packet is received.
• Generally WiFi networks connect back to a 802.3
  Ethernet connection, but they can connect 2
  devices to one another (AdHoc Networks) or
  connect a computer directly to the internet.

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Background History - WiMax

• Brief Discussion of 802.11 Wifi

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Motivations - LTE

• Chosen European standard likely to be used
  throughout the world
• Large companies have committed to it
• Vodaphone (part owner Verizon Wireless)
• ATT
• High speed data throughputs
• 100 Mbps Downlink
• 50 Mbps Uplink
• Cost effective compared to UMTS based
  technologies
• Backwards compatible with all UMTS/GSM
  technologies
• High QoS for a wide range of applications

26
Motivations - LTE

• Can be deployed within existing GSM UMTS
  frequency bands along side existing networks
• Can use only a portion of the frequency band in
  the beginning and then can take more existing
  spectrum as old networks are phased out.
• Designed for high mobility
• Optimized for 0 15 km/h
• High performance still achievable for less than
  150 km/h
• Will still support anything up to 500 km/h

27
Motivations - UMB

• Motivations for EVDO Rev C (UMB)
• Backwards compatible with all CDMA 2000 Networks
• High speed data throughputs
• 280 Mbps Downlink
• 75 Mbps Uplink
• Low latency connections
• An average of 16 ms (32-byte, RTT) end-to-end
  network latency
• High QoS for a wide range of applications
• Seamless mobility
• Efficient frequency re-use deployment

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Motivations - WiMax

• Time to market
• Has already seen a small launch in the United
  States Clearwire
• Has seen similar deployments around the world.
• Large companies have committed to it
• Sprint-Nextel (XOHM)
• SK Telecom (WiBro is a variant of WiMax and has
  been launched in South Korea)
• There have been discussions to morph WiMax into
  the LTE Umbrella and make it a stepping stone to
  LTE
• This may be a play simply to discredit WiMax and
  make it sound inferior
• The newest revision of Mobile WiMax (802.16m) is
  expected from the IEEE sometime this year and
  should bring the theoretical speeds for a mobile
  application up to a level of those expected from
  LTE UMB.

29
Deterrents

• Long Term Evolution (LTE)
• Time to market
• Not expected to have a widespread deployment
  until 2012
• Components not available until late 2009
• 4 years behind Mobile WiMax
• Ultra Mobile Broadband (UMB)
• Time to market Components first available in
  late 2009 to 2010.
• No corporate commitments throughout world
• Even the majority of current CDMA carriers have
  chosen other platforms
• Mobile WiMax
• Speeds are not up to the level of UMB LTE
• Downlink capable of 46 Mb/s (without MIMO)
• Less than half that of UMB LTE
• note that 802.16m is expected to raise these
  figures to 100 Mb/s and should be out sometime
  this year and available around 2010. Note this
  is still 2 years before LTE is expected to widely
  deployed.
• Not officially classified as 4G by European
  standards due in part to insufficient speeds
• Unproven, a lot is riding on the success of
  Sprints consumer launch (XOHM)
• Success could lead to more build outs worldwide
  turning it into a global standard

30
Deterrents

• All three technologies face another crucial
  issue. Backhaul
• As speed increase the need for more and more
  leased lines increases. Fiber alleviates some
  pressure but is limited in roll outs and is
  relatively expensive.
• Alternative options include but are not limited
  to
• Microwave
• Fixed WiFi or WiMax
• Dark Fiber
• ADSL or SHDSL
• PDH or SDH/SONET infrastructures
• E1/T1, E3, T3, STM-1/OC-3
• Cable Coaxial lines
• None of these options is widely available in the
  U.S., Especially in the mass rural parts of the
  county.
• Sprint is supposedly using Microwave to provide
  the backhaul to their WiMax towers where fiber is
  not yet available.

31
Spectrum Allocations

• Long Term Evolution (LTE)
• 1.25 MHz to 20 MHz chunks
• Can operate in all 3GPP frequency bands in paired
  and unpaired spectrum allocations
• Can sit in the same band as existing 3GPP
  networks. Allows for LTE to be phased in while
  older technologies are phased out.
• Ultra Mobile Broadband (UMB)
• 1.25 MHz up to 20 MHz
• Mobile WiMax
• Any frequency below 66 GHz
• Fixed channel sizes of 3.5 MHz, 5 MHz, 7 MHz, 10
  MHz, and 20 MHz.
• Mobile channel sizes of 5 MHz, 8.75 MHz and 10
  MHz.
• This does not phase Sprint or Clearwire as both
  have almost 120 MHz of spectrum in their areas,
  but smaller companies could face issues when only
  operating in 10 or 20 MHz blocks.

32
Services and QoS

• Streaming of high quality video and audio
• Video calling
• VOIP for phone calls
• Provide enhanced data speeds for both handheld
  devices and laptop connect cards
• Could replace the traditional wired networks as
  they are much cheaper than fiber to the curb, and
  speeds look to be the same if not higher than
  those offered via wired today
• This would be for the following services
• HSI to replace DSL/Cable Modems
• Digital Phone for the Home
• IPTV or TV over IP to replace standard cable or
  satellite provider
• This would give previously only mobile operators
  the ability to sell the very lucrative triple
  play that, up until now, only existing LEC and
  cable operators have been able to.

33
Services and QoS
Category Current Environment 4G
Possibilities
Source UMTS Forum, "Standardising the future of
mobile communications with LTE (Long Term
Evolution)." Towards Global Mobile Broadband
(2008)
34
Services and QoS

• Companies are also looking to build 4G chips into
  more electronic devices than just cell phones and
  laptops
• Looking for every electronic device to have a 4G
  connection to the internet
• Fridge could download recipes and auto update
  shopping list with what you need
• Digital cameras would be able to instantly
  upload photos to photo sharing and social
  networking sites, as well as having the ability
  to send them via email directly from the camera
• MP3 players could download songs from anywhere,
  similar to the Apple iPod Touch but without the
  need for a WiFi connection
• Cars would be able to auto diagnose issues and
  email the mechanic to notify them of issues
• These are just a couple of the endless
  possibilities that 4th generation networks are
  trying to tap into

35
Network Architecture
Source Dahlman, Erik. 3G Evolution HSPA and LTE
for Mobile Broadband. First. London ELSEVIER,
2007.
36
Network Architecture - LTE

• LTE combines the following network protocols into
  a single air interface, utilizing the individual
  advantages of each one
• OFDMA
• MIMO (2x2 or 2x4)
• ARQ within the RLC sub layer and HARQ within the
  MAC sub layer
• FDD TDD
• SC-FDMA
• Up to 64 QAM DL and 16 QAM UL
• Turbo Coding (rate 1/3, 2 8 state constituent
  encoders and a contention-free internal
  interleaver)

37
Network Architecture - LTE

• The core network architecture of LTE has been
  given its own name. It is called System
  Architecture Evolution (SAE)
• SAE is relatively similar to the GPRS Core
  Network that includes some basic modifications.
• Most notably a simplified architecture
• Spectrum allocations from 1.25 MHz up to 20 MHz
• Can support 200 simultaneous VOIP users across a
  cell consisting of 5 MHz
• Provides interference reduction through power
  control and link adaptation techniques
• A common node B. Acts as a common gateway for
  all of the access technologies that access the
  network
• Can support handoffs between both 3GPP networks
  and non-3GPP networks
• This should allow legacy CDMA2000 operators to
  interface their old networks with LTE

38
Network Architecture - LTE
Source Myung, Hyung G.. "Technical Overview of
3GPP Long Term Evolution (LTE)."2007.
39
Network Architecture - UMB

• UMB is a proprietary technology to Qualcomm Inc.
  
• There is only a limited amount of information
  available regarding the actual architecture and
  physical properties of the technology.
• This a summary of the available information
  available from Qualcomm white papers.

40
Network Architecture - UMB

• According to the CDG UMB combines the following
  network protocols into a single air interface,
  utilizing the individual advantages of each one
• CDMA
• OFDMA
• MIMO
• SDMA
• FDD

41
Network Architecture - UMB

• Spectrum allocations from 1.25 MHz up to 20 MHz
• Can support 1000 simultaneous VOIP users across
  20 MHz FDD
• A flat network architecture
• Simplifies core network design
• Eliminates the need for centralized base station
  controllers (BSCs)
• A converged-access network (CAN) design that
  enables seamless mobility
• A multi-route feature that enables fast switching
  between base stations and provides requisite
  support for latency-sensitive applications
• Layer 2 and layer 3 tunneling mechanisms to
  simplify the network interface
• Adaptive interference management

42
Network Architecture - UMB
Source "UMB Network Architecture." Qualcomm Inc
Dec 2007 02 Apr 2008 lt7. http//www.qualcomm.com/c
ommon/documents/white_papers/UMB_Network_Achitectu
re.pdfgt.
43
Network Architecture - WiMax

• Mobile WiMax combines the following network
  protocols into a single air interface, utilizing
  the individual advantages of each one
• TDM access with variable frame sizes (2 - 20 ms)
• OFDM
• MIMO
• Adaptive Antenna System (AAS)
• QPSK, 16 QAM, 64 QAM
• Convolutional Codes, Convolutional Turbo Codes,
  Block Turbo Codes, and Low-Density Parity Check
  (LDPC) Codes
• Hybrid ARQ
• TDD, FDD H-FDD

44
Network Architecture - WiMax

• The following channel bandwidths are supported
• 5 MHz, 7 MHz, 8.75 MHz, 10 MHz and 20 MHz
• These spectrum allocations can be anywhere within
  the following licensed spectrum bands
• 2.3 GHz, 2.5 GHz, 3.3GHz, 3.5GHz
• While WiMax can support both TDD and FDD, it is
  only truly supporting TDD at this point. The
  ability to do FDD should be built into a later
  revision.

45
Network Architecture - WiMax
"Network Architecture." HiperMAX-micro. Airspan.
7 May 2008 lthttp//www.airspan.com/products_wimax_
microcell_hipermax.aspxgt.
46
Physical Layer MAC Protocols - LTE

• The physical layer was defined with the bandwidth
  constraints of LTE in mind.
• This is important in allowing it to easily adapt
  to various spectrum allocations
• It is also important to get as much data
  throughput as possible through the connection
• LTE uses up to 64 QAM for the downlink and up to
  16 QAM for the uplink. In contrast, its
  broadcast only channel uses on BPSK.
• LTE also uses turbo coding for all transport
  blocks
• It uses a rate 1/3 code
• It also has 2 8-state constituent encoders as
  well as a contention-free QPP internal
  interleaver
• The turbo coding scheme uses a trellis
  termination technique.
• Before the turbo coding, transport blocks are
  segmented into byte aligned segments with a
  maximum information block size of 6144 bits.
• Error detection is supported by the use of 24 bit
  CRC.

47
Physical Layer MAC Protocols - LTE

• Both the downlink and the uplink share the same
  frame structure.
• Both can use either a FDD or TDD mode of
  operation.
• LTE frames are defined as 10 ms
• The frames are divided into 10 subframes
• Each subframe is further divided into two slots
• Each .5 ms slot can consist of either 6 or 7 ODFM
  symbols
• This structure is shown below

Source Myung, Hyung G.. "Technical Overview of
3GPP Long Term Evolution (LTE)."2007.
48
Physical Layer MAC Protocols - LTE

• LTE has three access procedures
• Cell Search
• Cell search is the protocol for when the mobile
  handset (terminal) finds a cell tower (cell) that
  it potentially would like to communicate with
• The mobile handset needs to identify the cell
  tower and needs to estimate the frame timing of
  that cell tower.
• There are three main steps in performing a cell
  search
• To assist in these steps the cell tower
  broadcasts a primary and secondary synch bit in
  the downlink
• The mobile handset uses the primary synch bit to
  find the primary timing of the tower during a 5
  ms slot
• The mobile handset needs to detect the
  cell-identity information and determine the frame
  timing. This can be done by checking the pairs
  of slots where the secondary synch but should be
  transmitted
• The cell tower now broadcasts the system
  information so that the mobile handset can
  determine the remaining parameters.

49
Physical Layer MAC Protocols - LTE

• LTE has three access procedures
• Random Access
• This is when the terminal requests a
• connection setup
• There are 4 steps to the random access
• procedure
• The terminal first sends a random-access
  preamble. This allows the eNodeB to estimate the
  transmission timing of the terminal
• The network then sends a timing advance command
  if the terminals transmission timing is off.
  This also assigns uplink resources to the
  terminal
• The mobile-terminal then sends its identity to
  the network. This is sent using the
  UL-Scheduling protocols specific to the network.

• The network then sends a contention-resolution
  message to the terminal. This resolves and
  conflicts of multiple terminals attempting to
  access the same resources.

Source Dahlman, Erik. 3G Evolution HSPA and LTE
for Mobile Broadband. First. London ELSEVIER,
2007.
50
Physical Layer MAC Protocols - LTE

• LTE has three access procedures
• Paging
• When the mobile device is not in use it is
  allowed to go to sleep
• Paging sets the protocols for a network-initiated
  connection setup
• When the mobile device goes to sleep it
  automatically wakes up at pre-defined intervals
• These pre-defined intervals are set up to
  coincide exactly with the L1/L2 control signaling
  to prevent the need for a dedicated channel like
  what is used in UMTS

Source Dahlman, Erik. 3G Evolution HSPA and LTE
for Mobile Broadband. First. London ELSEVIER,
2007.
51
Physical Layer MAC Protocols - WiMax

• WiMax uses QPSK, 16 QAM and 64 QAM in the
  downlink and QPSK and 16 QAM in the uplink
• WiMax also uses the following coding schemes
• Tail-Biting Convolutional Code
• Convolutional Turbo Code
• Block Turbo Code (optional)
• Low-Densitiy Parity Check Code (LDPC) (optional)
• Zero Tailed Convolutional Code (optional)
• WiMax also uses a scheduling algorithm
• Each mobile handset competes for a slot only once
  (for initial entry into the network).
• Once it has won an access slot from the base
  station it cannot lose it unless it disconnects
  from the tower.
• The tower can enlarge and contract the individual
  time slots, but no matter what, it remains
  assigned to the specific subscriber station

52
Physical Layer MAC Protocols - WiMax

• The mobility versions of WiMax have three basic
  handover methods defined. They are
• Hard Handover (HHO)
• The mobile handset scans the nearby base stations
  and gathers a list of all the possible base
  stations.
• It uses this information to determine if a
  handoff is necessary. Both the base station and
  mobile handset can decide to start the handoff
• Once this decision is made the handset
  immediately starts communicating with the new
  base station

53
Physical Layer MAC Protocols - WiMax

• The mobility versions of WiMax have three basic
  handover methods defined. They are
• Fast Base-Station Switching (FBSS)
• The mobile handset maintains a set of multiple
  suitable base stations
• One base station is selected as the anchor and
  is where all the communications will take place.
• The mobile handset will continuously choose which
  ever base station has the best connection from
  its list.
• The mobile handset can change the anchor at any
  time without any handover signaling
• Macro-Diversity Handover (MDHO)
• Just like in FBSS the mobile handset keeps an
  anchor and a list of base stations
• However this time the mobile handset communicates
  with all base stations

54
Comparison of the Technologies
UMB simply states the use of the technologies.
There is no mention on specifics for DL or
U Includes latest release of 802.16M not
currently available
Source Scheim, Jacob. "A comparison of two
fourth generation technologies WiMax and
3GPP-LTE."Comsys. 2006.
55
Future of the Technology

• Long Term Evolution (LTE)
• Should see deployments throughout Europe, US and
  Asia
• Vodaphone, China Mobile, Verizon Wireless, ATT,
  T-Mobile (Europe Australia), Orange, NTT DoCoMo
• Estimates put 450 Million worldwide subscriber
  base by 2015
• Ultra Mobile Broadband (UMB)
• Looks to be a dead technology on arrival
• Qualcomm is now supporting LTE
• Mobile WiMax
• Currently deployed in US under brand XOHM
• On line in Chicago, Baltimore, Washington DC
• Consumer launch 2H 2008
• Deployed commercially in South Korea
• SK Telecom under the name WiBro

56
References

• Dahlman, Erik. 3G Evolution HSPA and LTE for
  Mobile Broadband. First. London ELSEVIER, 2007.
• TIA, "cdma2000 High Rate Packet Data Air
  Interface Specification." TIA-856-A Apr 2004 Apr
  2 2004 lthttp//www.tiaonline.org/standards/technol
  ogy/cdma2000/documents/TIA-856-A.pdfgt.
• Gozalvez, J. "1. Ultra Mobile Broadband Mobile
  Radio." Vehicular Technology Magazine, IEEE Mar
  2007
• "3G - Ultra Mobile Broadband." CDG Technology.
  2008. CDG. 2 Apr 2008 lthttp//www.cdg.org/technolo
  gy/3g_umb.aspgt.
• ABI Research, " A Poor Market Outlook for Ultra
  Mobile Broadband (UMB) Says ABI Research, but
  Qualcomms Future Still Secure." Business Wire 28
  Dec 2007
• "UMB Network Architecture." Qualcomm Inc Dec 2007
  02 Apr 2008 lt7. http//www.qualcomm.com/common/doc
  uments/white_papers/UMB_Network_Achitecture.pdfgt.
  
• " ULTRA MOBILE BROADBAND (UMB) SPECIFICATION IS
  PUBLISHED." CDG Mews Events. CDG. 2 Apr 2008
  lthttp//www.cdg.org/news/press/2007/Sep24_07.aspgt.
  
• "CDMA Buzz-Words EV-DO Rev C as UMB."
  PhoneNews.com 05 Dec 2006 02 Apr 2008
  lthttp//www.phonenews.com/cdma-buzz-words-ev-do-re
  v-c-as-umb-1615/gt.

57
References

• "What Is cdma2000?." cdma2000 Technology Family
  1xRTT, EVDO, UMB, and EVDV 02 Apr 2008
  lthttp//eogogics.com/talkgogics/tutorials/cdma2000
  gt.
• UMTS Forum, "Standardising the future of mobile
  communications with LTE (Long Term Evolution)."
  Towards Global Mobile Broadband (2008)
• Wikipedia. 2 Apr 2008 lthttp//wikipedia.org/gt.
• Scheim, Jacob. "A comparison of two fourth
  generation technologies WiMax and
  3GPP-LTE."Comsys. 2006.
• Litwin, Louis. "The principles of OFDM."RF Signal
  Processing. 2001.
• Myung, Hyung G.. "Technical Overview of 3GPP Long
  Term Evolution (LTE)."2007.
• Li, Bo. "A Survey on Mobile WiMAX."Wireless
  Broadband Access. 2007.
• Scrase, Adriane. "Overview of the Current Status
  of 3GPP LTE."ETSI. 2008.
• Collins, Gerry. "The Business Case for
  LTE."Nortel. 2007.
• Laine, Michael Steve Stanley . "3GPP LTE (Long
  Term Evolution)."University of Kansas. 2008.

58
Questions?