What is Mobile Computing? Wireless Communication Systems Mobile
Communication Systems Architecture Key Technologies of Mobile
Computing Applications
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Heterogeneous Wireless Communication World DAB: Digital Audio
Broadcast VHE: Virtual Home Environment DVB-T: Digital Video
Broadcast Terrestrial UMTS: Universal Mobile Telecommunication
System
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W IRELESS N ETWORKS Wireless communication networks IEEE 802.11
IEEE 802.15 IEEE 802.16 IEEE 802.20 Mobile communication networks
GSM GPRS WCDMA HSPA+ LTE
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IEEE 802 Refers to a family of IEEE standards dealing with
local area networks and metropolitan area networks The services and
protocols specified in IEEE 802 map to the lower two layers Data
Link Logical Link Control (LLC) Media Access Control (MAC) Physical
IEEE 802.11 IEEE 802.15 IEEE 802.16 IEEE 802.20
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IEEE 802 Standards
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WWAN / WMAN / WLAN / WPAN
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Note: NFC (Near Field Communication) A short-range high
frequency wireless communication technology which enables the
exchange of data between devices over about a 10 centimetre (around
4 inches) distance The technology is a simple extension of the
ISO/IEC 14443 proximity-card standard (contactless card, RFID) that
combines the interface of a smartcard and a reader into a single
device
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An NFC device can communicate with both existing ISO/IEC 14443
smartcards and readers, as well as with other NFC devices, and is
thereby compatible with existing contactless infrastructure already
in use for public transportation and payment NFC technology is
currently mainly aimed at being used with mobile phones
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Three main use cases for NFC card emulation: the NFC device
behaves like an existing contactless card reader mode: the NFC
device is active and read a passive RFID tag, for example for
interactive advertising P2P mode: two NFC devices are communicating
together and exchanging information
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Applications Mobile ticketing in public transport an extension
of the existing contactless infrastructure Mobile payment the
device acts as a debit/ credit payment card Smart poster the mobile
phone is used to read RFID tags on outdoor billboards in order to
get info on the move Bluetooth pairing pairing of Bluetooth devices
with NFC bringing them close together and accepting the
pairing
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Other applications Electronic ticketing airline tickets,
concert/event tickets, and others Electronic money Travel cards
Identity documents Mobile commerce Electronic keys car keys,
house/office keys, hotel room keys, etc. NFC can be used to
configure and initiate other wireless network connections such as
Bluetooth, Wi-Fi or Ultra-wideband
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IEEE 802.11 Standard and Amendments IEEE 802.11 - The WLAN
standard was original 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and
infrared [IR] standard (1997), all the others listed below are
Amendments to this standard, except for Recommended Practices
802.11F and 802.11T. IEEE 802.11a - 54 Mbit/s, 5 GHz standard
(1999, shipping products in 2001) IEEE 802.11b - Enhancements to
802.11 to support 5.5 and 11 Mbit/s, 2.4 GHz (1999) IEEE 802.11c
Bridge operation procedures; included in the IEEE 802.1D standard
(2001) IEEE 802.11d - International (country-to-country) roaming
extensions (2001) IEEE 802.11e - Enhancements: QoS, including
packet bursting (2005) IEEE 802.11f - Inter-Access Point Protocol
(2003) Withdrawn February 2006 IEEE 802.11 IEEE 802.15 IEEE 802.16
IEEE 802.20
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IEEE 802.11g - 54 Mbit/s, 2.4 GHz standard (backwards
compatible with b) (2003) IEEE 802.11h - Spectrum Managed 802.11a
(5 GHz) for European compatibility (2004) IEEE 802.11i - Enhanced
security (2004) IEEE 802.11j - Extensions for Japan (2004) IEEE
802.11-2007 - A new release of the standard that includes
amendments a, b, d, e, g, h, i & j. (July 2007) IEEE 802.11k -
Radio resource measurement enhancements (2008) IEEE 802.11n -
Higher throughput improvements using MIMO (multiple input, multiple
output antennas) (September 2009) IEEE 802.11p - WAVE Wireless
Access for the Vehicular Environment (such as ambulances and
passenger cars) (working June 2010) IEEE 802.11r - Fast roaming
Working "Task Group r" - (2008) IEEE 802.11s - Mesh Networking,
Extended Service Set (ESS) (working September 2010)
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IEEE 802.11T Wireless Performance Prediction (WPP) - test
methods and metrics Recommendation cancelled IEEE 802.11u -
Interworking with non-802 networks (for example, cellular) (working
September 2010) IEEE 802.11v - Wireless network management (working
June 2010) IEEE 802.11w - Protected Management Frames (September
2009) IEEE 802.11y - 3650-3700 MHz Operation in the U.S. (2008)
IEEE 802.11z - Extensions to Direct Link Setup (DLS) (August 2007 -
December 2011) IEEE 802.11aa - Robust streaming of Audio Video
Transport Streams (March 2008 - June 2011) IEEE 802.11mb
Maintenance of the standard. Expected to become 802.11-2011.
(ongoing) IEEE 802.11ac - Very High Throughput < 6 GHz
(September 2008 - December 2012) IEEE 802.11ad - Extremely High
Throughput 60 GHz (December 2008 - December 2012)
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IEEE 802.11 / Wi-Fi [/ Wa Fa /] Wireless Fidelity ( ) A
wireless-technology brand owned by the Wi-Fi alliance Promotes
standards with the aim of improving the interoperability of
wireless local area network products based on the IEEE 802.11
standards
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Common applications for Wi-Fi Internet and VoIP phone access,
gaming network connectivity for consumer electronics such as
televisions, DVD players, and digital cameras Wi-Fi Alliance a
consortium of separate and independent companies agrees on a set of
common interoperable products based on the family of IEEE 802.11
standards
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IEEE 802.11 Infrastructure Mode Uses fixed base stations
(infrastructure) which are responsible for coordinating
communication between the mobile hosts (nodes)
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IEEE 802.11 Ad Hoc Mode Mobile nodes communicate with each
other through wireless medium without any fixed infrastructure
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Mobile Ad Hoc Networks (MANET) Host moves frequently Topology
changes frequently No cellular infrastructure Multi-hop wireless
links Data must be routed via intermediate nodes A B A B
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802.11 /11a/11b/11g/11n
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IEEE 802.11n Improve network throughput over 802.11a and
802.11g with a significant increase in the maximum raw data rate
from 54 Mbit/s to 600 Mbit/s with the use of four spatial streams
at a channel width of 40 MHz In spatial multiplexing a high rate
signal is split into multiple lower rate streams each stream is
transmitted from a different transmit antenna in the same frequency
channel
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802.11n uses MIMO (Multiple Input Multiple Output)
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IEEE 802.11p (VANET) Motivation Vehicular Ad hoc NETwork
(VANET) Safety on US highways (2004) 42,800 fatalities, 2.8 million
injuries ~$230.6 billion cost to society Efficiency traffic jams
waste time and fuel in 2003, US drivers lost a total of 3.5 billion
hours and 5.7 billion gallons of fuel to traffic congestion Profit
safety features and high-tech devices have become product
differentiators
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VANET-based Emergency Vehicle Warning System
http://www.youtube.com/watch?v=yqtLvZrz2qE
http://www.youtube.com/watch?v=yqtLvZrz2qE Ford's "Talking"
Vehicles - Car-to-Car Communication Demo
http://www.youtube.com/watch?v=XBqCAVwQv0E
http://www.youtube.com/watch?v=XBqCAVwQv0E BMW Car-to-X
Communication http://www.youtube.com/watch?v=JzgwlXzO6v0
http://www.youtube.com/watch?v=JzgwlXzO6v0 InfoFueling network
http://www.youtube.com/watch?v=Cc19mcnzvpE * Ford Demonstrates
Vehicle-to-Vehicle Communication for Increased Safety
http://www.youtube.com/watch?v=RrCyl6pOAC0
http://www.youtube.com/watch?v=RrCyl6pOAC0
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What is VANET?
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Components in a VANET Moving vehicles with On-Board Unit (OBU)
Road Side Units (RSU) local broadcasting information IEEE 802.11
access point RSU
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On-Board Unit (OBU) Vehicle OBU WinXP devices Windows mobile
PDAs GPS tracker without user interface Text-based OBUs Pedestrian
OBU GPS phone Personal tracker
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Smart Vehicle A modern vehicle is a network of
sensors/actuators on wheels !
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VANET Architecture
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Differences between VANET and MANET VANETsMANETs Highly mobile
nodes moving in the same or opposite directions Nodes move randomly
Network shape can be best described by either a one-dimensional
line or a strip A square or torus shape With location information
and mapWithout location information Rely heavily on broadcast
transmission to disseminate traffic related information to all
reachable nodes (one to all & all to all) A query for a route
to a certain host (one to one & one to all) Energy supported by
carEnergy supported by battery (Energy conservation)
EmergencyNon-emergency Topology changes frequentlyTopology changes
slowly
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Vehicle Communication (VC) VC promises safer roads
I NTER - VEHICLE COMMUNICATION (IVC) S YSTEMS Completely
infrastructure-free Only onboard units (OBUs) are needed
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IVC SYSTEMS SIVC (Single-hop Inter-Vehicle Communication)
applications of short-range communications e.g., lane merging,
automatic cruise control MIVC (Multihop Inter-Vehicle
Communication) applications of long-range communications e.g.,
traffic monitoring (a) SIVC(b) MIVC
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R OADSIDE - TO -V EHICLE C OMMUNICATION (RVC) S YSTEMS
Communication between roadside infrastructure (RSU) and OBU Two
types of infrastructures Sparse RVC (SRVC) system Ubiquitous RVC
(URVC) system
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RVC S YSTEMS - SRVC Provide communication services at hot spots
Examples a busy intersection scheduling its traffic light a gas
station advertising its existence (and prices) parking availability
at an airport
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RVC S YSTEMS - URVC Provide all roads with high-speed
communication Require considerable investments for providing full
(even significant) coverage of existing roadways
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H YBRID V EHICULAR C OMMUNICATION (HVC) S YSTEMS Extend the
transmission range of RVC systems Vehicles communicate with
roadside infrastructure even when they are not in direct wireless
range by using other vehicles as mobile routers
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HVC Adv. & Disadv. Advantage less roadside infrastructure
Disadvantage network connectivity may not be guaranteed in
scenarios with low vehicle density
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Vehicular Ad Hoc Network (VANET) Message propagates to
destination using a number of intermediate links
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If vehicle mobility causes links to break, message rerouted
using a different path
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Challenges Physical layer limited bandwidth Link layer
congestion control, latency, throughput, fairness and scalability
Network (routing) layer rapid topology changes and network
fragmentation
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WAVE (IEEE 1609) / DSRC (802.11 P )
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WAVE (W IRELESS A CCESS IN V EHICULAR E NVIRONMENTS )
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WAVE IEEE 1609 Mode of operation used by IEEE 802.11 devices to
operate in the DSRC band (5.850-5.925 GHz) Defines architecture
communications model management structure security and physical
access Primary architecture components are OBU, RSU, and WAVE
interface
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P1609.1 Resource Manager P1609.2 Security Services for
Applications and Management Messages P1609.3 Networking Services
P1609.4 Multi-Channel Operations VAVE Standard Components
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WAVE (IEEE 1609) / DSRC (802.11 P )
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DSRC (D EDICATED S HORT R ANGE C OMMUNICATIONS ) ASTM Standard
E2213-03, based on IEEE 802.11a Name of the 5.9 GHz Band allocated
for the ITS communications 5.855-5.925 GHz range divided into 7
licensed channels (each 10 MHz) Short range radio 300m (1000m max)
High data rate 6-27 Mbps ASTM: American Society for Testing and
Materials
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Half-duplex station can only send or transmit, but not both at
the same time Latency 200 s Communication modes vehicle to roadside
& vehicle to vehicle DSRC devices IEEE 802.11 systems using the
WAVE mode of operation in the DSRC band
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Based on ASTM Standard E2213-03 IEEE 802.11a PHY: OFDM
modulation IEEE 802.11 MAC: CSMA/CA IEEE 802.11e MAC enhancement:
message prioritization IEEE 802.11p Basis
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Longer ranges of operation (up to ~1000 meters) High speed
vehicles (up to ~500 km/h) Extreme multipath environment (many
reflections with long delays) Need multiple overlapping ad-hoc
networks to operate with extremely high quality of service Support
automotive applications (e.g. reliable broadcast) IEEE 802.11p
Requirements
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Control Channel (CCH) broadcast communication dedicated to
short, high-priority, data and management frames safety-critical
communication with low latencies initialization of two-way
communication on SCH Service Channel (SCH) two-way communication
between RSU and OBU or between OBUs specific applications, e.g.
tolling, internet access different kinds of applications can be
executed in parallel on different service channels IEEE 802.11p
Multi-Channel
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DSRC C HANNEL A LLOCATION 7 licensed channels (each 10
MHz)
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DSRC C HANNEL A LLOCATION
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DSRC
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H OW DSRC W ORKS ? RSU announces to OBUs 10 times per second
the applications it supports OBU listens on channel 172
authenticates RSU digital signature executes safety apps first
then, switches channels executes non-safety apps returns to channel
172 and listens
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IEEE 1609.4 E XTENSION FOR MULTI - CHANNEL COORDINATION
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C HANNEL C OORDINATION Each Universal Time Coordinated (UTC)
second is split into 10 Sync Intervals (each 100ms) Every Sync
Interval is composed of alternating CCH Interval (50ms): all WAVE
devices have to monitor the CCH SCH Interval (50ms): nodes may
switch to a SCH (RX or TX) Synchronization is performed via
GPS
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IEEE 802.11 P M EDIA A CCESS C ONTROL (MAC) Based on
Distributed Control Function (DCF) with CSMA/CA CSMA/CA if the
channel is sensed busy before transmission then the transmission is
deferred for a random interval Basic access mode and RTS/CTS mode
are used on SCH
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DCF: BASIC ACCESS MODE A node transmits a DATA packet if it
senses the channel to be idle The receiver upon receiving an
error-free packet, returns an ACK The sender if the transmitting
node does not get an ACK back, it enters into back-off and
retransmits after the back-off period Basic access mode suffers
from hidden node problem
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ABC H IDDEN N ODE PROBLEM A is sending to B C is ready to
transmit to B it does not detect carrier and thus begins
transmission this produces a collision at B Cs carrier sense did
not provide the necessary information since station A was hidden
from it RTS/CTS solves the hidden terminal problem!
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DCF: RTS/CTS MODE When a node A wants to send a packet to node
B, it initially sends a Request-to-Send (RTS) A
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Upon correctly receiving the RTS, node B responds with
Clear-to-Send (CTS) B
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After receiving the CTS, node A sends the DATA packet to node B
B A
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If node B receives the DATA packet correctly, it sends an
Acknowledgment (ACK) back to node A Any node that hears an RTS or a
CTS is prohibited from transmitting any signal for a period that is
encoded in the duration field of the received RTS or CTS
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The duration fields in RTS and CTS are set such that nodes A
and B will be able to complete their communication within the
prohibited period (Network Allocation Vector, NAV) Finally, if a
node does not get a response to an RTS or a DATA packet, it enters
into an exponential backoff mode
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The dark bars below node C and D indicates their NAV
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B ACKOFF I NTERVAL When channel is busy, choose a backoff
interval in the range [0, cw] Count down the backoff interval when
medium becomes idle Count down is suspended if medium becomes busy
again When backoff interval reaches 0, transmit RTS Binary
exponential backoff in 802.11 DCF when a node fails to receive CTS,
cw is doubled up (up to an upper bound, cw max ) when a data
transfer completes successfully, cw is reset to cw min
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IEEE 802.11 P MAC C HANNEL A CCESS
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IEEE 802.15 The 15 th working group of the IEEE 802 and
specializes in Wireless PAN (Personal Area Network) standards IEEE
802.15.1 IEEE 802.15.1-2002 a Wireless PAN standard based on
Bluetooth v1.1 specifications including a media access control and
physical layer specification IEEE 802.15.1-2005 based upon the
additions incorporated into Bluetooth v1.2 IEEE 802.11 IEEE 802.15
IEEE 802.16 IEEE 802.20
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the IEEE Study Group discontinues their relationship with the
Bluetooth SIG (the later versions of Bluetooth will not become
future IEEE standards) Bluetooth specifications Bluetooth 1.0 and
1.0B Bluetooth 1.1 Bluetooth 1.2 (data rate: 1Mbps) [not IEEE
standard] Bluetooth 2.0 + EDR (Extended Data Rate) Bluetooth 2.1 +
EDR (data rate: 3Mbps) Bluetooth 3.0 + HS (High Speed) (data rate:
perhaps 24Mbps) Bluetooth V4.0 (Ble; Bluetooth low energy) (data
rate: perhaps 24Mbps)
802.16 WiMAX (Worldwide Interoperability for Microwave Access )
WirelessMAN A telecommunications technology aimed at providing
wireless data over long distances in a variety of ways, from
point-to-point links to full mobile cellular type access Enable the
delivery of last mile wireless broadband access as an alternative
to cable and DSL
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Intel WiMAX Vision 82
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WiMAX for Fixed and Mobile Access 83 CPE (Customer Premise
Equipment) /
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WiMAX Consumer Last Mile 84
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WiMAX Backhaul for Business 85
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WiMAX Nomadic / Portable 86
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2008.11.13 HTC Max 4G GSM / WiMAX 88
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IEEE 802.16 Operation Modes / Topologies Point to MultiPoint
(PMP) / star topology Mesh mode / mesh topology Mobile Multihop
Relay (MMR) / tree topology
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IEEE 802.16 Entities BS Base Station central role in PMP mode
coordination role in resource management connection/gateway point
to other networks (backhaul, core IP, Internet) SS Subscriber
Station fixed station MS mobile station MSS - Multiple Subscriber
Station (playing role of an AP for LAN/WLAN) in-door or out-door RS
Relay station used in Mobile Multihop Relay (MMR) 90
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802.16 Relevant Standards 802.16d (2004) basic fixed mode-
standard PMP / mesh modes, 70 Mbps 802.16e (2005) (Mobile WiMAX)
lower data rate, 15 Mbps full nomadic and mobile use including
handover enhancements to 802.16-2004 better support for QoS
scalable OFDMA supports devices : mobile smart phones, PDAs,
notebooks, laptops 91
Slide 92
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802.16j Mobile Multihop Relay (MMR) enhance the normal PMP
frame structure backward compatible with PMP mode new relay
networking protocols multi-hop relay connections between SS/MS and
BS coverage extensions throughput enhancement actually not mesh
mode but tree topology 93
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802.16m amendment for advanced air interface based on IEEE
802.16e-2005 expected data rates 100 Mbps for mobile applications 1
Gbps for fixed applications spectral efficiency, improve voice
capacity, reduce latency support for location-based services
improve multicast broadcast services 94
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IEE 802.16 Relevant Standards Evolution 95
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96 Mobile WiMAX (IEEE 802.16e) To enable low-cost mobile
Internet applications To realize the convergence of mobile and
fixed broadband access in a single air interface and network
architecture
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Mobile WiMAX enabling a variety of usage models in the same
network
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Mobile WiMAX Technology and Network Evolution Roadmap
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WiMAX Network Reference Model
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WiMAX Logical Network Entities Mobile Station (MS) generalized
user equipment set providing wireless connectivity between a single
or multiple hosts and the WiMAX network in this context the term MS
is used more generically to refer to both mobile and fixed device
terminals
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Access Service Network (ASN) a complete set of network
functions required to provide radio access to MS layer 2 (L2)
connectivity with the MS according to IEEE 802.16 standards and
WiMAX system profile transfer of authentication, authorization, and
accounting (AAA) messages to the home network service provider
(HNSP) preferred NSP discovery and selection relay functionality
for establishing layer 3 (L3) connectivity with MS (i.e., IP
address allocation) radio resource management to enable mobility,
the ASN may also support ASN and CSN anchored mobility, paging and
location management, and ASN-CSN tunneling
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Base station (BS) primarily consists of radio related functions
of an ASN interfacing with an MS over-the-air link according to MAC
and PHY specifications ASN gateway (ASN-GW) an aggregation of
centralized functions related to QoS, security, and mobility
management for all the data connections served by its association
with BSs through R6 hosts functions related to IP layer
interactions with CSN through R3 interacts with other ASNs through
R4 in support of mobility
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Connectivity Service Network (CSN) a set of network functions
that provide IP connectivity services to WiMAX subscriber(s) the
CSN may further comprises network elements such as routers, AAA
proxy /servers, home agent, and user databases as well as
interworking gateways or enhanced network servers to support
multicast and broadcast services and location-based services
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key functions IP address management AAA proxy or server QoS
policy and admission control based on user subscription profiles
ASN-CSN tunneling support subscriber billing and interoperator
settlement inter-CSN tunneling for roaming CSN-anchored inter-ASN
mobility connectivity to Internet and managed WiMAX services such
as IP multimedia services (IMS), location-based services,
peer-to-peer services, and broadcast and multicast services
over-the-air activation and provisioning of WiMAX devices
WiMAX Network uses IP Based Simple Protocol Structure SS/MS ASN
CSN BSASN-GW
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MAC / PHY Protocol Structure in Mobile WiMAX Release 1.0
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WiMAX MAC Layer (IEEE Std. 802.16-2004)
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Service Specific Convergence Sublayer (CS) MAC MAC CS (Service
Access Point SAP) IEEE 802.16-2004 sub-layer (SDU) sub-layer (PDU)
Common Part Sublayer (CPS) CPS MAC sublayer CPS MAC SAP CS QoS
802.16 MAC MAC CPS Security Sublayer (SS) Key /
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110 WiMAX Network Architecture and Evolution (Release 1.0) ASN
and CSN mobility (for mobility support) Paging and location
management IPv4 and IPv6 connectivity Preprovisioned/static QoS
Optional radio resource management (RRM) Network
discovery/selection IP/Ethernet CS support Flexible credentials,
pre- and postpaid accounting Roaming (RADIUS only) 3GPP I-WLAN
compatible interworking
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111 Over-the-air (OTA) activation and provisioning
Location-based services (LBS) Multicast broadcast service (MBS) IMS
integration Dynamic QoS and policy and charging (PCC) compatible
with 3GPP Release 7 Telephony VoIP with emergency call services and
lawful interception Full NAP sharing support Handover data
integrity Multihost support Ethernet services, VLAN Enhanced open
Internet services Diameter-based AAA WiMAX Network Architecture and
Evolution (Release 1.5)
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112 Multimedia session continuity 3GPP/2 interworking
(optimized handover ) Network management, including self- organized
/optimized networks (SONs) Seamless WiFi-WiMAX handover Roaming
enhancements Support for multihop relay stations Support for
femto-cells Device reported metrics WiMAX Network Architecture and
Evolution (Release 2.0)
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802.20 MBWA (Mobile Broadband Wireless Access) IEEE 802.20 or
Mobile Broadband Wireless Access (MBWA) an IEEE Standard to enable
worldwide deployment of multi-vendor interoperable mobile broadband
wireless access networks a packet-based air interface designed for
IP-based services low-cost, always-on, and mobile broadband
wireless networks, nicknamed as Mobile-Fi the goals of 802.20 and
802.16e, the so-called "mobile WiMAX", are similar IEEE 802.11 IEEE
802.15 IEEE 802.16 IEEE 802.20
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Technical description IP roaming & handoff (more than 1
Mbps) new MAC and PHY with IP and adaptive antennas optimized for
full mobility up to vehicular speeds of 250 km/h operates in
licensed bands (below 3.5 GHz) utilizes packet architecture low
latency