WiMAX. 2 Topics WiMAX Protocol About WiMAX Physical layer MAC layer Fixed / Mobile WiMAX WiMAX vs Wi-Fi WiMAX applications.

WiMAX

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Topics

WiMAX ProtocolAbout WiMAXPhysical layerMAC layer

Fixed / Mobile WiMAX WiMAX vs Wi-Fi WiMAX applications

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What is WiMAX

Worldwide Interoperability for Microwave Access

a "last mile" broadband wireless access (BWA) alternative to cable modem, Digital Subscriber Line (DSL) or T1/E1 service.

Wireless Metropolitan Area Network (WMAN) Based on IEEE 802.16

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IEEE 802.16 Standards 802.16.1-2001 (10-63 GHz, line-of-sight, up to 134Mbit/s) 802.16.2 (minimising interference between coexisting

WMANs.) 802.16a-2003 (2-11 Ghz, Mesh, non-line-of-sight) 802.16b-2004 (5-6 Ghz) 802.16c (detailed system profiles) 802.16e-2005 (Mobile Wireless MAN) – called Mobile

WiMAX 802.16m-2011, data rates of 100 Mbit/s mobile & 1 Gbit/s

fixed (4G) 802.16-2012, 16p, 16n, current

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Standard

FamilyPrimary Use

Radio Tech

Downlink (Mbit/s)

Uplink (Mbit/s)

Notes

WiMAX 802.16Mobile Internet

MIMO-SOFDMA

128 (in 20MHz bandwidth)

56 (in 20MHz bandwidth)

IEEE 802.16m expected to offer peak rates of at least 1 Gbit/s fixed speeds and 100Mbit/s to mobile users.

LTEUMTS/GSM

General 4G

OFDMA/MIMO/SC-FDMA

100 (in 20MHz bandwidth)

50 (in 20 MHz bandwidth)

LTE-Advanced expected to offer peak rates up to 1 Gbit/s fixed speeds and 100 Mb/s to mobile users.

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Purpose of WiMAX Providing mobile broadband connectivity across

cities and countries through a variety of devices. Providing a wireless alternative to cable and

DSL for "last mile" broadband access. Providing data, telecommunications (VoIP) and

IPTV services. Providing a source of Internet connectivity as

part of a business continuity plan.

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Fixed and Mobile WiMAX

Fixed WiMAX is optimised for home/office networks

Mobile WiMAX is optimised for mobiles

8http://www.conniq.com/InternetAccess_WiMAX-02.htm

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Fixed WiMAX Architecture

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WiMAX as cellular alternative

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WiMAX as a mobile voice and data network is potentially exponentially more efficient (profitable) than the legacy cellular infrastructure

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WiMAX Architecture

MIB – Management Information Base

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802.16 protocol

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802.16 protocol stack

802.16 covers data link and physical layer

802.16 MAC Sublayer Protocol

Classes of service

1. Constant bit rate service.

2. Real-time variable bit rate service.

3. Non-real-time variable bit rate service.

4. Best-effort service.

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Physical layer (PHY)

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PHY cont. BPSK: 1 bit/baud QPSK: 2 bits/baud QAM-16: 4 bits/baud QAM-64: 6 bits/baud Example: a 25 MHz bandwidth, QPSK can

deliver 50 Mbps, QAM-16 100 Mbps, QAM-64 150 Mbps

Baud (Bd): measure of the symbol rate; the number of distinct symbolic changes (signalling event) made to the transmission medium per second in a digitally modulated signal

25 Bd means that 25 symbols are transmitted per second.

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PHY cont. TDD (time-division duplex)

- use same bandwidth for uplink and downlink- controlled by timing

FDD (frequency-division duplex)- use different frequency for uplink and downlink

OFDM (orthogonal frequency-division multiplexing)- enhancement of frequency division multiplexing (FDM)- maximise use of bandwidth

Also Adaptive Antenna Support (AAS) and MIMO

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TDD and FDD

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Figure 16.5: Frame structure at the physical layer (TDD)

In each time slot, a frame is in the air. The base station fills the data to send to substation in the downstream subframe; the substations fill the data to send to the base station in the upstream subframe.

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OFDM

FDM OFDM

OFDM uses bandwidth which is not available for use in FDM

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WiMAX Antennas

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Omni directional antennaOmni directional antennas are used for point-to-multipoint configurations.

its energy is greatly diffused in broad-casting 360 degrees

This limits its range and ultimately signal strength

good for situations where there are a lot of subscribers located very close to the base station

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Sector antennasfocusing the beam in a more focused area

offers greater range and throughput with less energy

Many operators will use sector antennas to cover a 360-degree service area rather than use an omni directional antenna

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Panel antennas

a flat panel of about one foot square

often used for point-to-point applications

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Frequency Plan

By reusing frequencies at different base stations, a WiMAX operator can avoid interference from their own network

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WiMAX vs Wi-Fi

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WiMAX vs Wi-Fi cont.

WiMAX is designed to cover large area (multiple homes/buildings), while Wi-Fi is to cover small area (a home/building)

30Comparison of WiMAX, WiFi and 3G technology

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WiMAX applications

Broadband Internet Multimedia IP multimedia subsystem (IMS) Cellular Alternative A clear alternative to connect areas without pre-

existing physical cable or telephone networks or just areas without BB access

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Broadband Internet

• Fixed WiMAX is substitute for T1

• Mobile WiMAX has larger coverage than WiFi

WiMax in UK

UK Broadband, a subsidiary of PCCW (owned by Hong Kong Telecom)  Freedom4 (formerly Pipex Wireless) had the necessary spectrum to launch these wireless networks in the UK, but only Freedom4 opted to do so with a WiMax network in Milton Keynes and Stratford Upon Avon. These WiMax networks were up and running in real world situations years before LTE arrived on the scene.

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Freedom4′s WiMAX Licence Sold For £12.5m.  June 29, 2010.

http://www.europa-network.com/wimax/

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Why did LTE beat WiMax

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Most WiMax backers, including Clearwire in the United States (which has already built WiMax networks in many US cities), have signalled their intent to move across to LTE. It was never cost effective for WiMax networks to compete effectively against fixed-line broadband networks.

What happened was that LTE came along early enough so that all operators adopted it,” said James. “No one adopted 16m because there were no economies of scale. Indeed, all WiMax operators have signalled they will move to LTE.

WiMax is dead as a mobile technology but it is not dead as a fixed technology.

UK Broadband brought Freedom4′s spectrum, because it is adjacent to UKB’s spectrum. “We now have 124MHz of LTE”

UK Broadband’s chief executive, Nicholas James

http://www.ukbroadband.com/

Sprint will KILL OFF WiMax in 2015

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http://www.theregister.co.uk/2014/10/06/sprint_wimax_to_close_in_2015/

Third-ranked US mobile network Sprint appears to be poised to kill off its implementation of its less-regarded 4G technology, WiMax. The spectrum it frees up will all move to LTE.

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Number of WiMAX subscriber worldwide from 2010 to 2014 (in millions)

http://www.statista.com/statistics/277656/number-of-wimax-subscriber-worldwide-since-2010/

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Reference Tannenbaum “Computer Networks” Stallings “wireless communications &

Networks” Frank Ohrtman: “Wimax overview”:

http://www.wimax.com/education/wimax/wimax_overview

“The 802.16 WirelessMAN™ MAC: It’s Done, but What Is It?” (2001-11-12)