Wimax 2

WiMAX 2.0

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Agenda

What is WiMAX?

Standards and Specifications

Reasons for WiMAX 2.0

Key features of WiMAX 2.0

Quality of Service in WiMAX 2.0

References

Research papers reviewed

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What is WiMAX?

Worldwide Interoperability for Microwave Access

It is intended to provide a standardized BWA

solution to provide “broad-band wireless to the

masses’

“WiMAX is not a standard”.

WiMAX is a marketing term trademarked by the

WiMAX Forum to describe 802.16-based

technology.

802.16 is the technology standard.

WiMAX™ technology is based upon the

IEEE 802.16 standard enabling the delivery of

wireless broadband services anytime, anywhere.

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Standards and Specifications

What IEEE 802.16 standard?802.16 standard frequency range

10-66 GHz requires Line of sight and is single carrier

2-11GHz requires non line of sight and is both single and multiple

carrier

Describes Wireless MANs

Broadband access up to 30 miles for fixed stations and 3-10 miles for

mobile stations.

Connection oriented

Point to multi-point architecture with roof top or tower mounted

antennas.

The IEEE 802.16m standard used by WiMAX 2.0Goal: To provide an advanced air interface for operation in the licensed

bands while mmaintaining support for legacy devices based on ealier variants

and provide significant performance increases for new devices.

Devices categories include:

Advanced Mobile Stations (AMS), Advanced Base Stations (ABS), and

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Reasons for WiMAX 2.0

WiMAX 1.0Suffered from latencies because of big frame

size of 5ms.

Customers' demand for data servicesHigh speed data rates

Operators quest for a timely and cost

effective service to meet customers' high

expectations.5

WiMAX response

WiMAX responded by:•Providing an advanced air interface for operation in the

licensed band.•Worked on the PHY and MAC Layer specications

•Maintain support for legacy devices

•Provide siginificant performance for new devices•Advanced Mobile Stations (AMS)

•Advanced Base Stations (ABS)

•Advanced Relay Stations (ARS)

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WiMAX response

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PHY and MAC layer

specifications

•PHY layer•New frequencies introduced (450-470MHz, 1710-2025MHz,

2110-2200MHz).

•İntroduction of FDD in addition to TDD

•Uses OFDMA as opposed to OFDM in WiMAX 1.0

•Support for heterogeneous users•Low data rates but reliable link

•High data rates even if delays in transimissions occur

•Use of Adaptive Modulation and Coding schemes•16QAM due to fading signal changes to QPSK

•16QAM due to improved signal gain changes to 64QAM

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PHY and MAC layer

specifications

•MAC Layer•Quality of service

•Uses 3-message request intsead of 5-message request used by

WiMAX 1.0.

•Four cases of Handover•R1 to R1 base station uses legacy protocol

•ABS to R1 and R1 to ABS uses legacy handover in ABS

•ABS to ABS uses new protocol with three stages i.e initiation,

preparation and execution.

•Hybrid Automatic Repeat Request (HARQ)•Ensures that packets are sent and recieved correctly

•Based on stop and wait for acknowlegment

•Channels can run in parallel (up to 16 channels) to avoid delay

of waiting for acknowlegement this increases the performance.

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Date ratesWiMAX 2.0 increases the transmission

bandwidth to up to 100MHzSub-carriers over multiple frequency bands (carrier

aggregation)

LatenciesIntroduced a 20ms super frame to reduce

framing overhead and control bits.

WiMAX 2.0 divided this frame into 8 sub-

frames, but kept the 5ms for compatibility with

1.0

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Increased Coverage and Spectral Efficiency

20-30% increase in cell coverage area in a typical

non line-of-sight environment.

Support for more advanced antenna systems

(Adaptive antenna systems).

Beam forming techniques to focus on the

wireless beam between the base station and the

subscriber

Frequency band support

FDD and TDD frequency bands for deployment of

systems.11


Support for heterogeneous usersLow data rates but reliable links

High data rates even if delays from transmissions

occur.

Higher order Multiple Input Multiple Output

(MIMO)Single User MIMO

Improve the link performance, by providing robust

transmissions with spatial diversity,

Multi User MIMOEnable resource allocation to communicate data to two

or more MSs . MU-MIMO enhances the system

throughput.

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Key features of WiMAX 2.0 cont’d

•Femto cells•Short range ABS used in

SOHO environments

•Support high throughput

over small cells

•Three subscriber groups

of femto cells•CSG-closed- only

members

•CSG-Open- anyone but

members have priority

•OSG- anyone can

connect

•Self organizing

networks which reduce

the costs of operation

and maintenance•

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ITM advanced features

defined in IEEE802.16m

(WiMAX 2.0)Relay modes to improve coverage and efficiency

Transparent mode increase through put with in the base

station’s covergae area.

Non transparent mode increase the coverage extension

of a base station.

Increased Capacity for Data and VoIP100Mbps for mobile and 1Gbps for fixed staions.

Inter-working with other Wireless Networks

Ensures backwards compatibility with WiMAX 1.0

based on 802.16e-2009 and improves coexistence and

enhances inter-working with other Radio Access

Technologies (RAT)

Multi carrier aggregation

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Quality of Service in WiMAX 2.0

WiMAX 2.0 achieves QoS at both the PHY

and MAC layersAt the PHY layer the focus is on optimising the

use of the radio resources

At the MAC layer QoS is about efficient

schedulling and allocation of bandwidth to meet

the need QoS requiremnts of IP sessions.

Parameters are defined per service flow

include:Traffic priority

Maximum sustained traffic rate

Minimum reserved traffic rate

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QoS classes defined in WiMAX 2.0

Unrestricted grant service (UGS)

Real time service for fixed size data packets

Real time Polling service (rtPS)

Intended for variable size data packets on a periodic basis e.g MPEG

video

Extended rtPS

Uses both UGS and rtPS

Allocations are dynamic

Non-real time Polling service

Unicast polls on a regular basis

Service flow recieves request opportunities even during network

congenstion

Best effort

For best effot traffic.16

Comparision of QoS classes

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References

WiMAX and the IEEE 802.16m Air Interface

Standard-April 2010. WiMAX Forum.

http://www.wimaxforum.org/sites/wimaxforum.or

g/files/document_library/802.16e_enhanced_next_

step_wimax_roadmap_v2.2_attribution.pd

http://www.comsocscv.org/docs/Talk_032509_Wi

MAXUpdate.pdf

http://www.wimaxforum.org/resources/technical-

specifications

http://www.wimaxforum.org/sites/wimaxforum.or

g/files/document_library/wimax_802.16m.pdf

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Research Paper 1

•Next Generation 4G WiMAX Networks•Written by

•Shantanu Pathak and Shagun Batra, Department of

Telecommunication, SRM University, Chennai, India

•Discusses•Various PHY and MAC layer specifications for WiMAX as a 4G

technology

•ITM advanced specifications and how WiMAX achieves these

specifications.

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Research Paper 2

•Interference Management for 4G Cellular Standards•Authors

•Nagen Himayat and Shilp Talwar from Intel cooperation

•Anil Rao and Robert Soni from Alcatel Lucent

•Compare the interference management solutions across

IEEE 802.16m (WiMAX 2.0) and 3GPP-LTE

•Increase in system capacity degrades the performance

experienced by cell edge users because of the increased

interference from out of cell transmission.

•Proposed management schemes •Semi-static radio resource management (RRM) through adaptive

fraction frequency reuse, Power Control and Smart Antenna

techniques to null interference from other cells/ 20

Questions

•Describe the key features of WiMAX 2.0.

•Compare and contrast the QoS classes used in

WiMAX 2.0.

•Describe briefly the concept of adaptive modulation in

WiMAX 2.0

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Thank you

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Technology

Wimax 2