WiMAX in Depth

WIMAX in Depth – IEEE 802.16Copyright © LEVER Technology Group PLC - http://www.lever.co.uk - All Rights Reserved

Copyright © 2005 LEVER Technology Group PLC - http://www.lever.co.uk1

WiMAX In Depth

IEEE 802.16

Worldwide Interoperability for Microwave Access

V2



Course Instructor

Don Cochrane



Introduction & Objectives

• Overview

– This three-day course is about the IEEE 802.16 Broadband Wireless Access Standard

• Key benefits:

– Understand what has been standardised

– Learn the basic concepts underpinning Fixed Wireless Access

– Appreciate what the 802.16 standard means and how the technology operates

• It assumes:

– A technical background, some telecoms would be useful

Introduction & Objectives

As a general strategy, the course does not reproduce pages of data figures. This is because:1. The figures may change with subsequent releases of the standard - anyone needing them must refer to the latest issue of the standard2. Relatively few people need the actual numbers and overloading everyone with non-essential data is counter-productive3. Trying to remember them is unnecessary and hard work4. Lists of parameters are very boring to both present and to listen to.



Housekeeping

� Start/Finish Time

� Lunch

� Coffee Breaks

� Emergencies

� Toilets

� Mobile Phones

� Questions



Course Agenda

• Overview of IEEE 802.16and WiMAX

• 802.16 Family of Standards

• RF Design and Characteristics

• 802.16 Air Interface - Physical Layer

• 802.16 - MAC layer

• Quality of Service

• WiMAX Security

• Planning a WiMAX Network

• Network Designand Implementation

• Interference

• Delivering Voice over IP Services (VoIP)

• Current trends with WiMAX

Over Three Days



CHAPTER ONE

Overview of WiMAX and 802.16



Something to Remember

• People focus on throughput in bits per second.

• We see claims about 11 Mbps, 100 Mbps, etc.

• Two things:

– This rate is shared between uplink and downlink so, for example, WiFi (802.11b) claims 11 Mbps but the one way rate

is around 5.5 Mbps

– Its SHARED between all the users in the area

• Think of the radio capacity of a cell/Access Point as a cake:

– The cake is the available capacity of the cell.

– If users get a big slice then we have few users

– If users each get a crumb then everybody gets a bit

– But it could be a VERY small bit

Something to Remember

An excellent example is 3G (UMTS) a range of different data rates are available up to 384 kbps per user. However with 384 kbps to a user there may be at most 3 such users taking most of the cell capacity and planning constraints may drop that to just 1 such user.Alternatively there could be 250+ users each with just a few kbps.



System Architecture

• SS – Subscriber Station

• TE – Terminal Equipment (The customer’s stuff)

• RS - Repeater Station

CoreNetwork

BaseStation

Directional Antenna

or

Intercell

Link

SS TE

SS TE

SS TE

SS TE

SS TE

G

RS

RS

~~

~

~

~

~

~~

TE TE

Omnidirectional Antenna

System Architecture

A real system may have all or only some of these, e.g. there may not be Repeaters if there is no mesh.Repeaters are used when the Base Station has no line of sight (LOS) to the SS and also to increase the effective range of the Base StationTraffic may pass through one or more Repeaters to reach an SS.



Fixed Wireless Access

• Replace the local loop between a customer and a local exchange

– Traditionally copper pair used

• Straight telephone service using radio is ‘Wireless Local Loop’

• We are looking to provide a better service than that

– Just like ADSL and Cable Modems do for copper pairs

– Looking for data rates well above 2 Mbps

• Hence ‘Broadband Wireless Access’

• Large coverage distances of up to 50 kilometres under LOS conditions and typical cell radii of up to 5 miles/8 km under NLOS conditions.

LOS = Line of Sight NLOS = Non-Line of Sight

Fixed Wireless Access

LOS doesn’t mean just a really narrow path between buildings from transmitter to receiver but a reasonably wide free space path. Technically, this is defined as 60% of the first Fresnel zone.



The Idea – The First Mile

• Cheaper than cable

• Easy to deploy and withdraw

• High bit rates (several

Mbit/s per customer)

• Frequencies used: 2.4 to 40 GHz, and lower (from

LOS to nLOS solution)

• Associated services :

VoIP, broadband internet, multimedia…

Source: ATDI



NLOS is GOOD!!

• Means the transmit

mast needn’t be the

highest thing around

• This makes planning a

lot easier

• Also installation at

customer site – needn’t be on the roof

NLOS is GOOD!!

In a NLOS link, a signal reaches the receiver through reflections, scattering, and diffractions. The signals arriving at the receiver consists of components from the direct path, multiple reflected paths, scattered energy, and diffracted propagation paths. These signals have different delay spreads, attenuation, polarizations, and stability relative to the direct path. The multi path phenomena can also cause the polarization of the signal to be changed. Thus using polarization as a means of frequency re-use, as is normally done in LOS deployments can be problematic in NLOS applications. How a radio system uses these multi path signals to an advantage is the key to providing service in NLOS conditions. A product that merely increases power to penetrate obstructions (sometimes called “near line of sight”) is not NLOS technology because this approach still relies on a strong direct path without using energy present in the indirect signals. Both LOS and NLOS coverage conditions are governed by the propagation characteristics of their environment, path loss, and radio link budget. There are several advantages that make NLOS deployments desirable. For instance, strict planning requirements and antenna height restrictions often do not allow the antenna to be positioned for LOS. For large-scale contiguous cellular deployments, where frequency re-use is critical, lowering the antenna is advantageous to reduce the co channel interference between adjacent cell sites. This often forces the base stations to operate in NLOS conditions. LOS systems cannot reduce antenna heights because doing so would impact the required direct view path from the CPE to the Base Station. NLOS technology also reduces installation expenses by making under-the-eaves CPE installation a reality and easing the difficulty of locating adequate CPE mounting locations. The NLOS technology and the enhanced features in WiMAX make it possible to use indoor customer premise equipment (CPE). This has two main challenges; firstly overcoming the building penetration losses and secondly, covering reasonable distances with the lower transmit powers and antenna gains that are usually associated with indoor CPEs. WiMAX makes this possible, and the NLOS coverage can be further improved by leveraging some of WiMAX’s optional capabilities.



The Market Place

• Point to Multi-Point is normal

– Needs Line of Sight to Base Station at higher frequencies

– Lower Frequencies can support Non-line of sight

One Base Station

Several thousand customers

in a 4 - 5 km range

Not mobile

Not nomadic

Fixed users

The Market Place



Mesh?

Each user acts as a relay to other users

Solves the line of sight problem

Users may have two antennasWIBNI antennas were steerable remotely to add new users

Mesh?

The provider can use the facilities of Network Management to reconfigure the configuration. This may be necessary when a new building blocks an existing line.



The First Global Standard

• There are local standards and proprietary standards

– ETSI have been working on HiperAccess

– LMDS/MMDS, etc. exist but are analogue and mostly in the US.

• The IEEE Standard first appeared in 1999/2000

– Extra sections followed before they updated the whole thing

in 2004

– Now we have a mobile version

The First Global Standard



Technologies

• Many technologies for the same goal:

– Microwave links

– WLL (LMDS)

– W-MAN (WiFi, WiMAX, WiBRO, Flash-OFDM©) WiFi is very

distance limited and vulnerable to Bluetooth

– Mobile (3G), UMTS already launched commercially. Bit rate

lower than initial expectations. HSDPA being rolled out

– Broadcast (DVB-H, T-DAB,Wi-TV). Studies and tests for DVB-H•MW links require expensive deployment costs

– Mesh networking

WiBRO (Wireless Broadband) is a Korean-developed portable Internet system in the 2.3 GHz band. It offers 30 50 50 MBPS over a range of 1.5 km. It has now allegedly been folded into 802.16



Deployment: WiMAX for Backhaul

• This, like hotspot backhaul is really a niche market

• Insufficient to make a serious business or warrant huge

investment

• Similar to rural access.

• Some pundits predict that the main markets are in urban areas

and the mobile (802.16e) market (IDC)

This in April 2005. Dishnet Wireless plans to spend US$57 million to rollout national Wi-Fi hotspot network in India via WiMax: The firm wants to jumpstart service ahead of rivals which are committed to wireline operations. Dishnet will use WiMax (or pre-WiMax, more likely until certification) to handle backhaul among a potential 6,000 Wi-Fi hotspots. By next March, they will link up 38 cities, starting with Bangalore. The owner of Dishnet Wireless sold a wireline DSL business (Dishnet DSL) to a former government-owned Internet provider. He also has an interest in the Barista coffee chain which will offer Dishnet Wireless service.



Deployment: WIMAX Hotspot Solution

• This from Aradial

WiMAX

Opportunity: A carrier is deploying two new cell towers and a Wi-Fi hotspot in a

rural community within the next two months. They want to be able to connect their cell towers to their core network and the hotspot to

the Internet.

Solution:WiMAX provides the best solution for this challenge because itprovides a cost-effective, rapidly deployable point-to-point

backhaul solution.

Radius Server (AAA) and Radius Billing Solutions.The diagram shows how Aradial Radius server is connected to the network.Hardware (Access clients) : ISP routers, PPPOE, VOIP Gateways and PBX, Hotspots Access points, Hotspots Access gateways, and Mobile AAA (WAP,GPRS,MMS and 3G).Radius server communicates with the radius billing server for authentication and accounting



Deployment: Last Mile

• A WISP wants to expand its service coverage to underserved

markets. QoS is a significant factor for this deployment because

some of the new customers are local government and small and medium businesses requiring a guaranteed level of service for

certain applications. Deployment cost and vendor interoperability

is key because many users within the target-market segment may end up owning their own WiMAX CPE.

• WiMAX provides the best and the most cost-effective broadband

solution to this challenge because the cost of deploying and

providing traditional broadband services is prohibitively

expensive. WiMAX is designed from the ground up to provide a

fast, cost-effective and easy-to-deploy solution with built-in QoS. WiMAX is based on IEEE standards and WiMAX-certified

products are vendor interoperable.

Source: IntelWISP – Wireless Access Service Provider



Operators

• Building and proving a business case should rely on deployment hypothesis

• Established operators:-

– Complement areas where DSL is not already available (rural areas)-

– Wireless alternative to DSL to face the increasing Bit Rate demand for Residential and SoHo areas

• Alternative operators:-

– Offering a wireless solution to the «standard» access to the subscriber (optical fibre, cable, dedicated line, non-modifiable installation…)

• Segmentation of the Market according to customers’precise expectation

• According to the target market one technology or a combination of solutions will best fit the needs

• Whatever the solutions, the technologies will co-exist



Business Plans must cope with

Customers

• Different types of customers want different things

• Different degrees of price sensitivity

– Premium companies

– SMEs

– SoHos

– Residential

– Different revenues

– Target marketing

– Also branding



Operator Needs

Source: Redline Communications



ETSI BRAN

Source: ETSI

• Broadband Radio Access Network initiative

• Addressing more than one area

– Inside buildings - HiperLAN

– LANs to Servers - HiperLink

– Access to public networks - HiperAccess

ETSI BRAN

The work of the ETSI Broadband Radio Access Networks (BRAN) project and its HIPERACCESS family is looking toward a greater symmetry with broadband delivery possible in both uplink and downlink directions supporting ATM and/or IP transport. To this end, the BRAN project has strong links to the ATM-Forum and their wireless ATM group. Additionally, the HIPERACCESS group expects to draw on the expertise of the HIPERLAN standardisation groups, also within the BRAN project, which have drafted standards for Radio LAN short range, licence exempt, equipments also employing ATM transport in the 5GHz spectrum area.HIPERACCESS systems will use fixed bi-directional radio connections to convey broadband services between users‘ premises and a broadband core network. HIPERACCESS is aimed particularly at residential customers and small businesses, where the economic benefits of using the shared radio medium are greatest. Radio access will be particularly useful to allow networks to be built economically by the competing telecommunications service providers of the future.



All the Hipers….

• HIPERLAN/2 – Short range, high speed access (25 Mbit/s typical

data rate) to a variety of networks including the UMTS core

networks, ATM networks and IP based networks. Range 30 to 150 Metres. Connection oriented.

• HIPERACCESS – Long range, point-to-multipoint, high speed

access (25 Mbit/s typical data rate) by residential and small

business users

• HIPERLINK – Short range, very high speed interconnection of

HIPERLANs and HIPERACCESS, e.g. up to 155 Mbit/s over

distances up to 150 m.

W.I.B.N.I. HiperAccess and IEEE 802.16 were, at least, compatible?

ETSI seem to have been working on this for years and years!

All the HIPERS

HIPERACCESS target range is 5 km. Products seem very quiet or non-existent

W.I.B.N.I. Wouldn’t it be nice if…



HIPERAccess

• First HIPERAccess specification approved in 2002

• The first deliverables for the HIPERACCESS broadband radio

access system are out:

– The HIPERACCESS Physical Layer specification (TS 101 999)

HIPERACCESS System Overview (TR 102 003)



Aimed at Europe

• The ETSI work has a much narrower frequency range than the

IEEE work

– That is where we have radio spectrum available in Europe

– Licences already allocated in the 28 GHz band in some

countries

– Mainly targeted at 40.5 to 43.5 GHz band

• Are the IEEE and BRAN efforts aligned?

– Yes, but only just!

– As late as October 26th, 2001, BRAN wrote to IEEE with

a liaison statement and assigning the job to someone

Aimed at Europe

The Liaison statement is document 80216-01_20. The scope of the letter only covered the frequencies, 2 - 11 GHz.



The Industry Group:

• Today every solution is custom and not interoperable. Every piece of WiMAX Forum Certified equipment will be interoperable with otherWiMAX Forum Certified equipment.

• WiMAX Forum Certified means a service provider can buy equipmentfrom more than one company and be confident everything works together.

• WiMAX Forum Certified means a more competitive industry.

• WiMAX Forum Certified means lower costs.

• WiMAX Forum Certified means faster growth for broadband wireless –everywhere around the globe.

• July 2005, in Spain, the WiMAX Forum Certification test lab at Cetecom has opened

Important Word!

Source: WiMAX Forum

The WiMAX Forum™ is working to facilitate the deployment of broadband wireless networks based on the IEEE 802.16 standard by helping to ensure the compatibility and inter-operability of broadband wireless access equipment. The organization is a nonprofit association formed in June of 2001 by equipment and component suppliers to promote the adoption of IEEE 802.16 compliant equipment by operators of broadband wireless access systems.

WiMAX Forum is comprised of industry leaders who are committed to the open interoperability of all products used for broadband wireless access.•Support IEEE 802.16 standard •Propose and promote access profiles for their IEEE 802.16 standard •Certify interoperability levels both in network and the cell •Achieve global acceptance •Promote use of broadband wireless access overall



WiMAX Players

• Main Members – the Board: Airspan Networks, Alvarion, Aperto

Networks, AT&T, BT, Fujitsu, Intel, OFDM Forum, Proxim, WiLAN

• Principal Members (Cheaper!) include Ericsson and Nokia, Cisco, Nortel, etc.

• Mainly targeted at the 2 – 11 GHz band



A Maker’s Problem…

• 802.16 is a very large specification designed to cover the fixed

broadband wireless access needs of a variety of different

situations.

• There are allowances for different physical layers for different

frequency bands

• The system can be IP or ATM centric…….

• An implementer faces a tough decision: build an IEEE 802.16 compliant system implementing every possible feature, even

those features you know will never be used in systems for your

target customers?

• Or, do you build a system with only the subset of features you need for your market, risking accusations of non-compliance and

lack of interoperability?

it is clear that the IEEE 802.16 Air Interface Specification is a very large specification. It was designed to cover the fixed broadband wireless access needs of a variety of different situations. There are allowances for different physical layers for different frequency bands and country-by-country frequency use restrictions. There are features that allow one to build an IP centric system or an ATM centric system depending upon the needs of customers. The specification is designed to cover application to diverse markets from very high bandwidth businesses to SOHO and residential users.Because of the wealth of options available, an implementer currently faces a tough decision. Do you build an IEEE 802.16 compliant system implementing every possible feature, even those features you know will never be used in systems for your target customers? Or, do you build a system with only the subset of features you need for your market, risking accusations of non-compliance and lack of interoperability?



Conformance

• The IEEE standards process stops short of providing fully

comprehensive conformance statements and test specifications.

• In order to ensure interoperability between vendors competing inthe same market, the WiMAX technical working groups were

created.

• The working groups address these issues by developing system

profiles and by producing PICS proforma, Test Suite Structure and Test Purposes specifications and Abstract Test Suite

specifications

• The methods for doing this follow ETSI and the ISO/IEC 9464 series (equivalent to the ITU-T x.290 series) of conformance

testing standards.



Test Specifications

• Test specifications are necessary to:

– Ensure that equipment and systems claiming compliance to

the standard or a profile have been sufficiently tested to demonstrate that compliance.

– Guarantee that equipment from multiple vendors has been

tested the same way, to the same interpretation of the

standard, increasing the interoperability of the equipment.

– Enable independent conformance testing, giving further

credibility to the previous two items.

• ETSI is good at this area and has an official process which is

typically more complete than the IEEE process.

Test specifications are necessary to:•Ensure that equipment and systems claiming compliance to the standard or a profile have been sufficiently tested to demonstrate that compliance. •Guarantee that equipment from multiple vendors has been tested the same way, to the same interpretation of the standard, increasing the interoperability of the equipment. •Enable independent conformance testing, giving further credibility to the previous two items. This test specification initiative is an area where ETSI has an official process and is typically more complete than the IEEE process. ETSI follows the guidelines of the ISO/IEC 9646 series (ITU-T X.29x series). The Test Suite Structure and Test Purposes (TSS & TP) document and the Abstract Test Suite (ATS) specification, both described in ISO/IEC 9646-2 (ITU-T X.291), suit the purpose particularly well.



WiMAX Profiles 10 – 66 GHz

• WiMAX has defined two MAC system profiles that were rolled

back into IEEE 802.16c:

– Basic ATM system MAC profile

– Basic IP system MAC profile

• Two primary PHY system profiles were also defined:

– 25 MHz wide channel for (typically for U.S. deployments) use

in the 10-66 GHz range.

– 28 MHz wide channel for (typically European deployments) use in the 10-66 GHz range.

• The PHY profiles are the same except for their channel width and

their symbol rate, which is proportional to their channel width.Each primary PHY profile has two sub-profiles - FDD and TDD.

Because of the testing missing in the IEEE process, WiMAX created the 10-66 GHz technical working group. The profiles and test specifications are created by the technical working group, but actual testing is done by an authorized, independent laboratory. For each system profile, functions are separated between mandatory and optional feature classes by the PICS proforma document. There can be differences from one equipment manufacturer to another in implementing optional features, but mandatory features will be same in every vendor's product. Implementation of an optional feature is noted when the vendor fills out the PICS proforma.

The technical working has produced the following technical documents and have rolled them back into 802.16. All have been approved and published:•PICS proforma, per ISO/IEC 9646-7, describing mandatory and optional features for each 10-66 GHz system profile, enabling developers to state support for features. •TSS & TP document, per ISO/IEC 9646-2, for the 10-66 GHz system profiles. •RCT specification, specifying radio conformance testing, for the 10-66 GHz system profiles. In addition, the working group may develop an ATS specification, per ISO/IEC 9646-2 for 10-66 GHz.



WiMAX Profiles 2 – 11 GHz

• MAC and PHY System Profiles for IEEE 802.16a and HiperMAN

standards.

• The MAC profiles that are being developed include IP based versions for both WirelessMAN (Licensed) and WirelessHUMAN (License-exempt).

• While the IEEE 802.16a amendment has several physical layer profiles,

the WiMAX forum through its 2-11 GHz TWG is focusing on the 256 point FFT OFDM PHY mode as its initial and primary interoperability mode.

• Various channel rasters covering typical spectrum allocations in both

licenced and licence exempt bands around the globe have been chosen,

all supporting the 256-point FFT OFDM PHY mode of operation.

• In addition to System Profiles other testing and conformance documents

will be produced as part of the task of enabling certification and

interoperability.

– These include the Protocol Implementation Conformance Statement (PICS) Proforma, Test Suite Structure & Test Plan (TSS&TP), and

Abstract Test Suite (ATS).

In early 2003, the IEEE 802.16 standard was expanded with the adoption of the 802.16a amendment, focused on Broadband Wireless Access in the frequencies from 2 to 11GHz. Given the charter of the WiMAX forum, to promote certification and interoperability for Microwave Access around the globe, WiMAX agreed to expand and include the 802.16a standard in terms of addressing testing and conformance issues.The WiMAX 2-11 GHz Technical Working Group (TWG) has the mandate of creating testing and conformance documents as contributions to IEEE and ETSI standards bodies in support of the IEEE 802.16a and ETSI HiperMAN standards. Although WiMAX is actively working on and will produce the actual test documents, an authorized and independent laboratory that has been certified by WiMAX will conduct actual testing.The WiMAX 2-11GHz TWG is currently defining MAC and PHY System Profiles for IEEE 802.16a and HiperMAN standards. The MAC profiles that are being developed include IP based versions for both WirelessMAN (Licensed) and WirelessHUMAN (License-exempt).While the IEEE 802.16a amendment has several physical layer profiles, the WiMAX forum through its 2-11 GHz TWG is focusing on the 256 point FFT OFDM PHY mode as its initial and primary interoperability mode. Various channel rasters covering typical spectrum allocations in both licensed and license exempt bands around the globe have been chosen, all supporting the 256-point FFT OFDM PHY mode of operation.In addition to System Profiles other testing and conformance documents will be produced as part of the task of enabling certification and interoperability. These include the Protocol Implementation Conformance Statement (PICS) Proforma, Test Suite Structure & Test Plan (TSS&TP), and Abstract Test Suite (ATS).The WiMAX 2-11GHz TWG is currently defining MAC and PHY System Profiles for IEEE 802.16a and HiperMAN standards. The MAC profiles that are being developed include IP based versions for both WirelessMAN (Licensed) and WirelessHUMAN (License-exempt).While the IEEE 802.16a amendment has several physical layer profiles, the WiMAX forum through its 2-11 GHz TWG is focusing on the 256 point FFT OFDM PHY mode as its initial and primary interoperability mode. Various channel rasters covering typical spectrum allocations in both licensed and license exempt bands around the globe have been chosen, all supporting the 256-point FFT OFDM PHY mode of operation.In addition to System Profiles other testing and conformance documents will be produced as part of the task of enabling certification and interoperability. These include the Protocol Implementation Conformance Statement (PICS) Proforma, Test Suite Structure & Test Plan (TSS&TP), and Abstract Test Suite (ATS).



The OFDM Forum

• Just in passing:

• Members of the WiMAX Forum

– A nested forum…

• Dedicated to promoting the concept of Orthogonal Wavelength

Division Multiplexing

• In several wireless areas.

• Seen as a good bandwagon to be on

– They may be right…

The OFDM Forum is a voluntary association of hardware manufacturers, software firms and other users of orthogonal frequency division multiplexing (OFDM) technology in wireless applications. The OFDM Forum was created to foster a single, compatible OFDM standard, needed to implement cost-effective, high-speed wireless networks on a variety of devices. OFDM is a cornerstone technology for the next generation of high-speed wireless data products and services for both corporate and consumer use. With the introduction of the IEEE 802.11a, ETSI BRAN, and multimedia applications, the wireless world is ready for products based on OFDM technology.



Relationship between 802.11 (WLANs)

and 802.16 (Wireless Access)

Scope

Speed

Range

Radio Freq

802.16 Wireless Access

Raw rates >120 Mbps

Local Area: 4 - 6 km

Licenced 10 - 60 GHz

Licenced 2 - 11 GHz

Unlicenced 5-6 GHz

802.11 WLAN

11-53 Mbps

Picocell, office,

Starbucks, etc.

10-20 m

Unlicenced 2.4/5.8 GHz

802.15 WPANs

1 – 20 Mbps10 Metres or so

Unlicenced

2.4 GHz

Note that

WiMEDIA is

looking to go to 400 Mbps

Relationship between 802.11 (WLANs) and 802.16 (Wireless Access)

The distinction between WLANs and wireless access is important. The WLAN business is growing very quickly at the moment. Wireless access is for non-moving users, a replacement for a physical connection whilst theWLAN is for nomadic users, i.e. they aren’t mobile when using the system but move between uses. The Starbucks initiative was that you go into a Starbucks, get a cup of coffee and sit and receive email, etc. whilst you drink it. Then you finish the coffee but haven’t finished emailing so you drink more coffee. The really smart deal that Starbucks did (on their side) however, finished off the (dumb) carrier concerned.



A Maker’s View of WiMAX Performance

Environment Typical Sector Channel

Cell Size Throughput

Urban Indoor (NLOS) 1 km 21 Mbit/s 10 MHz

Suburban Indoor (NLOS) 2.5 km 22 Mbit/s 10 MHz

Suburban Outdoor (LOS) 7 km 22 Mbit/s 10 MHz

Rural Indoor (NLOS) 5.1 km 4.5 Mbit/s 3.5 MHz

Rural Outdoor (LOS) 15 km 4.5 Mbit/s 3.5 MHz

Source: Alcatel

Source: Relationship between channel bandwidth, cell size, LOS/NLOS, and throughput. (Source: Laine, Boettle, Boscher, Feijt: Alcatel Strategy White Paper – WiMAX, making ubiquitous high-speed data services a reality, 28 June 2004)



Reported 802.16 Performance

• Two main bands/flavours: 10 – 66 GHz and less than 10 GHz

• For the lower band, vendors report:

– Hawaii, through dense palm trees and rolling hills (complete non-LOS), 3 km (1.86 miles), 26 Mbps

– Ireland, through ancient cathedrals and other landscape ruins

(complete non-LOS), 12 km (7.45 miles), 24 Mbps

– Quebec City, Canada, partial visibility (optical line of sight (OLOS)), 53 km (33 miles), 18 Mbps

– Idaho, USA, 116 km (72 miles) with a local mountain partially

blocking the fresnel zone, 24 Mbps

– Boston, through dense trees (complete non-LOS), 3 km (1.86 miles), 26 Mbps

– Markham, ON, Canada, through a business park (complete

non-LOS), 3 km (1.86 miles), 56 Mbps

Source: Redline

Performance

The 68 members of the WiMax Forum define and test systems that can deliver up to 74 Mbits/s over distances up to 30 miles using spectrum bands that can range from 6 to 11 GHz -- largely in the 5.8 GHz (unlicensed) and 2.5-2.7 GHz (licensed) bands.



So what is WiBRO?

• WiBRO is the South Korean version of mobile WiMAX (The e

standard)

• South Korea has a higher density of broadband than anywhere else on earth

• WiBRO doesn’t have the frequency agility of WIMAX as it uses

the 2.3 GHz band – not generally available or only available with

limited channels (US)

• WiBRO grew out of the Korean HPi (High-speed Portable Internet)

project which originally ignored the IEEE work.

• HPi was also considered to be a portable solution versus a truly

mobile solution.

• HPi was being designed for sub-60km/h with sub-150ms intra-cell

handover versus the more stringent Mobile WiMAX requirements

of 120km/h and sub-50ms, respectively.

• In April 2004, the Koreans moved towards compatibility.

So what is WiBRO?

In February 2002 the South Korean government assigned 100MHz in the 2.3GHz spectrum for a portable Internet service.



WiBRO

• WiBro has two phases:

– WiBro Phase I, completed in March 2005 which still has many

of the “proprietary” elements of the original HPi standard with the network deployments taking place today in South Korea

based on this earlier phase.

– WiBro Phase II, largely complete by late 2005, more closely

aligns WiBro with the Physical and MAC layer requirements defined in IEEE 802.16

– WiBro Phase II products may be available for commercial

deployments in Q2 2008

WiBRO



Specific Differences

• WiBRO has SOFDMA but with the channel bandwidths and the number of associated subchannels different to the WiMAX Forum

version

• WiBro and Mobile WiMAX both use 5ms frames, but the number of symbols in each frame differs.

WiBRO Mobile WiMAX

No MIMO in Phase ISupports incremental

redundancy HARQ

TDD switching gap is differentSo can’t have both in same region

Handover by Fast Base Station

Switching (FBSS)

Architecture well developed:Radio Access Stations connect to

an Access Control Router

MIMO from the startSupports Chase combining

HARQ

TDD, FDD and half-duplex FDD

Hard Handoff (HHO)

Architecture still evolving:“Base Stations” connect to an

Access Services Network –

Gateway

Specific Differences

Outside of South Korea WiBro will eventually support 7MHz (1,024 tones) and 14MHz (2,048 tones).



Several Aspects to the Standard

• The overall scope of the ratified 802.16 covers the frequency

range 10 - 66 GHz

– Line of sight pretty essential

– Little or no multipath problems

– Radio channels are wide - 25 to 28 MHz

• The 2 - 11 GHz bands were dealt with by 802.16a

• The Unlicenced bands are being looked at by 802.16b

– Concentrated on the 5 - 6 GHz range

The goal is to keep the higher layers the same and

just change the physical layer

Now all combined in the 2004 Version of 802.16

Several Aspects to the Standard



Different Flavours

• Designation Frequency Applicability

• WirelessMAN-SC 10 – 66 GHz

• WirelessMAN-SCa Below 11 GHz licenced bands

• WirelessMAN-OFDM Below 11 GHz licenced bands

WirelessMAN-OFDMA Below 11 GHz licenced bands

WirelessHUMAN Below 11 GHz licence exempt bands

SC – Single Carrier

OFDM – Orthogonal Frequency Division MultiplexingOFDMA - Orthogonal Frequency Division Multiple Access

WirelessMAN means Wireless Metropolitan Area Network

WirelessHUMAN is Wireless High-speed Unlicenced Metropolitan Area Network

Different Flavours

The standard says that all implementations between 10 and 66 GHz must have the physical implementation of WirelessMAN-SC.The terms WirelessMAN, WirelessHUMAN and the flavours above are all registered trademarks of the IEEE,



Why so many?

• 10-66 GHz• Line of Sight (LOS) is needed• Little or no multipath interference

• Channels of 25 or 28 MHz

• Point to Multipoint, 120 MBps raw data rates

• Frequencies below 11 GHZ• LOS not required

• More multipath problems• Needs power management and interference strategy

• Licence exempt (probably 5 to 6 GHz)• As above but more interference

• Regulations limit power output

• Dynamic Frequency Selection (DFS) to avoid interferers

Why so Many?

Wireless performance varies with frequency.



Profiles

• This is a BIG standard (895 pages) with lots of options

• Easy to implement systems that comply but are incompatible

• To fix this, we have profiles for each flavour of 802.16

• Included in the standard

• These reference PICS proformas so the implementations can be

tested

– Protocol Implementation Conformance Statements

Profiles



Connection Oriented

• Like the telephone, Connection-Oriented communications needs a call or connection

• Three stages:

1) Call Setup Enter the destination address

2) Communication

3) Call Clearing Generate the billing record

Information always arrives in the right order.

Delays are constant

802.16 and ATM are connection-oriented

Connection Oriented

The telephone is perhaps the best known form of connection-oriented communication. The traditional telecommunications market is based on it.There are three distinct stages:The Call set-up stage where the destination address is entered. It is used just once so that the routing mechanism can find a way through the network(s) to the destination. The necessary resources are allocated to the call This route is remembered and is the one used throughout the communication. If there is a break in the route then the call is broken down and has to be remade.This stage includes ringing the bell and getting the destination to answer. This is the point at which charging starts.The second stage follows answering the call and is a communications session for as long as required. There is no routing required as the path for the call is already set up. As all communications follows the same route, nothing can get overtaken so the information never gets out of order. The end to end delays tend to be very constant.Finally there is call clearing when we hang up the ‘phone. This breaks down the route so that the resources used can be reallocated to another call. In public networks, it also ends charging and causes a call, record to be sent to the billing system.



Connectionless Communications

• Like a letter

• No pre-setup route

• All communications must carry the destination address

• Data can get out of order, lost and duplicated - hence it’s called ‘unreliable communications’

• The Internet Protocol IP is connectionless

Connectionless Communications

When using letters for communication, I have to put the recipient’s address on every letter or else they won’t get there; there is no memory or preset route.Because successive letters can take different routes, they can arrive in a different order to the original one.IP is connectionless and has these characteristics:

• Packets can arrive in the wrong order• Delays between packets can vary• Packets can get lost (lost in the post!)• All packets have to carry the full destination address.


3

Layered Systems

If we try to gather all the different aspects of a communications together in our brains at one instant then it is very difficult to avoid missing something or doing something wrong.Far easier is to consider parts of the problem one at a time. Layers split the task up. Each layer sits on top of the layer below and assumes that it has done its job. Each layer will do its part of the whole problem and pass the result up to the layer above.As each layer has a fixed interface to the layers above and below, it is possible to remove a layer and replace it by a different one which, provided it follows the interface standards, will not be noticed by the layers above or below it.


Layered Systems

• Communications is a complex subject.

• Breaking it down into brain-sized pieces makes things easier.

• This is a standard human approach to big problems

• Layers are a way of doing this

Is everyone happy with the OSI Layers?

At least up to Layer 4?

If so, we’ll miss this bit…


5

Layer 1 – The Physical Layer

The physical medium used to carry data can be any of a large range of possibilities. Many are based on copper conductors but the layer also includes fibre optics (glass), radio waves, infra-red and even wet string.The layer is point to point; between directly connected systems, not across a network. Therefore, between two end users, there may be a number of physical layers in use.A physical layer deals with moving bits as a stream of data; it is not concerned with bytes or data, just moving the bits from one point to another directly connected one.The layer, specified in ISO 8802.3, 4, 5, 7 and X.211, has over 50 different individual specifications including the V series of modems, IEEE 802.1 Ethernet, Token Ring, FDDI, etc.


Layer 1 - The PHYSICAL Layer

• Start at the lowest level - the cable, wire, fibre, etc.

• Provides the transparent transmission of bit streams between

directly connected systems - point-to-point


6

Layer 2 - The LINK Layer

The Link Layer, Layer 2, starts to consider bytes and is about data, not just bit streams. It is still point to point but can allow for the detection of errors in the transmission. Each link layer sits on to one Physical connection and It is still point-to-point with no knowledge at this level, of anything beyond the end points of the link.

Some link layers have error correction mechanisms as well as error detection.

These may use a retransmission technique whereby when the receiver detects that

there is a problem with a block of data, it requests that that block be sent again.

Retransmission takes time and decreases throughput but is essential for some

types of data. Payroll is a good example of one type of data that must get from the

sender to receiver without errors and without any parts missing or duplicated.

Other types of data cannot be retransmitted if there is an error because there is not

time.. An example of this is voice traffic; there is simply not enough time to get a

message back to the sender asking that a block be sent again; this would result in

worse distortion of the resulting sound than if the errored block was used. Video

signals are also in this category.

The service is defined in OSI 8886.


• Between directly connected systems (like the Physical Layer)

• Recognises bytes and blocks of data

• Some Link Layers do error recovery using retransmission

• Adds error detection.

Layer 2 - The LINK Layer


7

Layer 3 - The NETWORK Layer

At the Network Layer, we construct a path across a network which consists of many individual link layers. There are a series of problems which it is the job of the Network Layer to solve:

Finding the destination. Before any data can be delivered, the destination must be located. The address may be on a different network that is reached through a Gateway in which case the correct gateway must be found. The address may need conversion from one format to another, e.g. from a user-friendly text name to a string of numbers.

Finding a route to the destination. Just knowing where a destination is, is not enough, there may be several routes available to get to that destination, each with different capacities, levels of congestion and cost. Picking a suitable route is not always an easy task.

A connection-oriented Network layer will do this once at call Setup time and use that route for the duration of the connection.

A connectionless network will plot a route for every individual message or datagram that has to cross the network

A non-ISO Network Layer protocol is IP, the Internet Protocol which is connectionless.The service is defined in ISO 8348 and X.213. These are both connection-oriented and connection-less network services.


• Finds a path across a network - Routing

• Routing is done once for Connection-oriented communications - call setup and clearing

• Routing for every datagram for Connectionless.

Layer 3 - The NETWORK Layer

X.25, IP are Layer 3s

For this course we

don’t worry about

anything

above 3


18

IEEE 802.1 Structure

The OSI Stack is not the only one that has been developed. The IEEE stack has not come from the OSI standards body but has followed a different development route. It nevertheless does have a layered structure.This architecture introduces a layer, the Media Access Control or MAC, which effectively sits between the OSI layers 1 and 2. It defines how the data is formatted and how the users gain access to the common cable. It also defines error handling.Although it is not an IEEE standard, the IP layer is shown in its appropriate position to indicate where it fits into the scheme.


802.2 Logical Link Control (LLC)

802.3CSMA/CD

MACBus

802.5Token

PassingMACRing

802.11Wireless

LANs)

802.16BWA

OSI Layers

IP (Internet Protocol)3

Network Layer

2 Link

Layer

1 Physical

IEEE 802.1 Structure

802.xetc

The IEEE

standardises

up to the top of

Level 2.


All the Acronyms

ARP Address Resolution ProtocolARQ Automatic Retransmit RequestATDD Adaptive Time Division DuplexingATM Asynchronous Transfer ModeBNI Base Station Network InterfaceBR Bandwidth RequestBS Base StationCCS Common Channel SignalingCG Continuous GrantCID Connection IdentifierCLP Cell Loss PriorityCPS Common Part SublayerCPT CS Pass ThroughCS Convergence SublayerCSI Convergence Subprocess IndicatorChID Channel IDDAMA Demand Assign Multiple AccessDCD Downlink Channel DescriptorDES Data Encryption StandardDIUC Downlink Interval Usage CodeDL Down LinkDSA Dynamic Service AdditionDSC Dynamic Service ChangeDSD Dynamic Service DeletionEC Encryption ControlEKS Encryption Key SequenceEUI Extended Unique IdentifierFBWA Fixed Broadband Wireless AccessFC Fragment ControlFDD Frequency Division DuplexFSN Fragment Sequence NumberGM Grant ManagementGPC Grant Per ConnectionGPT Grant Per TerminalHCS Header Check SequenceHEC Header Error CheckHL-MAA High Level Medium Access ArbitrationHMAC Keyed-Hashing for Message AuthenticationHT Header TypeIE Information ElementIP Internet ProtocolIUC Interval Usage CodeIWF InterWorking FunctionLL-MAA Low Level Medium Access ArbitrationLLC Logical Link ControlLOS Line of SightMAA Medium Access ArbitrationMAC Medium Access ControlMIB Management Information BaseMIC Message Integrity CheckMPEG Moving Pictures Experts GroupMPLS Multi-Protocol Label SwitchingMSDU MAC Service Data UnitMTG Modulation Transition GapNNI Network to Network Interface (or Network Node Interface)

OOB Out of Band or Out of BlockPBR Piggy-Back RequestPCI Protocol Control InformationPDH Plesiochronous Digital HierarchyPDU Protocol Data UnitPHS Payload Header SuppressionPHSF Payload Header Suppression FieldPHSI Payload Header Suppression IndexPHSM Payload Header Suppression MaskPHSR Payload Header Suppression RulePHSS Payload Header Suppression SizePHSV Payload Header Suppression ValidPHY Physical LayerPI PHY Information elementPKM Privacy Key ManagementPM Poll Me BitPMD Physical Media DependantPPP Point-to-Point ProtocolPS Physical SlotPSH Packing Sub-HeaderPSP Packing Sub-Header PresentPTI Payload Type IndicatorPVC Permanent Virtual ConnectionQoS Quality of ServiceRS Reed-SolomonRTG Rx/Tx Transmission GapSA Security AssociationSAID Security Association IDentifierSAP Service Access PointSDH Synchronous Digital HierarchySDU Service Data UnitSF Service FlowSI Slip IndicatorSNI Subscriber Station Network InterfaceSS Subscriber StationSTG SS Transition GapSVC Switched Virtual ConnectionTC Transmission ConvergenceTDD Time Division DuplexTDM Time Division MultiplexTDMA Time Division Multiple AccessTDU TC Data UnitTEK Traffic Encryption KeyTFTP Trivial File Transfer ProtocolTLV Type-Length-ValueTTG Tx/Rx Transmission GapUCD Uplink Channel DescriptorUGS Unsolicited Grant ServiceUGS-AD Unsolicited Grant Service with Activity DetectionUIUC Uplink Interval Usage CodeUL UplinkUNI User to Network InterfaceUTC Coordinated Universal TimeVC Virtual ChannelVCI Virtual Channel IdentifierVP Virtual PathVPI Virtual Path Identifier


Page 1


WiMAX In Depth

IEEE 802.16

EXTRA Slides Used

Worldwide Interoperability for Microwave Access

V2


Page 2


Conditions

Extra Slide


Page 3


Two Options

• Soft Handovers – an MS communicating with more than one BS

is supported.

• Fast BS Switching – The MS is only transmitting and receiving from one BS at any one time but can switch from one BS to

another between frames

Extra Slide


Page 4


Privacy (in the Mobile Spec)

• Has two parts:

– An encapsulation Protocol using any of a set of cryptographic

suites and the rules for applying them

– A key management protocol/scheme for distributing

cryptographic keys

Extra Slide


Page 5


Architecture (Mobile)

Extra Slide


Page 6


WiMAX News

• November 16, 2005: WiBro Demonstrated in South Korea

• KT has shown off the homegrown mobile wireless data standard, WiBro: The standard has aspects of mobile WiMax and cellular technology, and may wind up converging with international mobile standards in the future. KT claims access at speeds of up to 60 kilometers per hour. They have two access devices that can function as WiBro modems and for voice calls. The service will roll out in 2006.

• February 21, 2006: Proxim Wireless Launches 3.5 GHz Products

• Ots Tsunami MP-16 uses the 3.5 MHz licenced band in Europe and Asia. The company says the product is in trials with nine firms. This band is not yet sorted out for use in the US, but is widely expected to lead licensed fixed WiMax deployments in Europe. The product is in queue for certification.

• January 19, 2006: First Certified WiMax Products Announced

• Aperto, Redline, Sequans and Wavesat have passed the first, simple round of testing which covers just a simple air link, and is so limited that a number of companies, including Alvarion, sat this round out.

• The four companies who have WiMax certification will certainly trumpet the fact, but it doesn’t change the dynamics of the industry. These initial certifications work in the 3.5 GHz band

• The press release from the WiMax Forum notes that the Spanish testing lab has 26 reservations for base station and customer premises equipment in the queue, which will be completed over the next two months. Subsequent waves of testing will cover more and more aspects of WiMax performance and interoperability, such as quality of service and advanced radio features.

Extra Slide


Page 7


More NEWS

• Nortel Builds Vast Albertan WiMax Network

• Nortel will roll out 8,000 square miles of WiMax: A governmental group and Nortel will build the network designed for 1 to 3 Mbps of access in heavily underserved areas of the province.

• December 07, 2005: Mobile 802.16e Standard Approved

• The basis for what will be mobile WiMax was approved by the IEEE today: Now that the standard is done, the hard part is developing hardware and replicating cellular infrastructure. All the challenges that faced rolling out 3G networks, land and planning rights for transmitters, etc. equally apply to mobile WiMax. Add to that, that it’s a new standard without the real-world evolution that’s happened in the mobile world, and there’s going to be a long lag between today and real, functioning, interoperable mobile WiMax equipment.

• Over the next two to three years, however, we’ll be reading stories every week in the mainstream press that continue to inflate the abilities of fixed WiMax—something mobile carriers are said to be very interested in for licensed use to backhaul tower traffic—and mobile WiMax. Fixed WiMax doesn’t operate in moving vehicles dozens of miles from a base station running at 72 Mbps. It can run fast, far, and mostly static, and not all three: you get fast when you’re close up and slow when you’re far away.

• TechDirt is saying it will be 2008 before we see anything resembling real mobile WiMax given the timetable that took fixed WiMax from 802.16 standards work to a ratified proposal to the very first stages of certification that don’t offer real interoperable benefits today.

Extra Slide


Page 8


And Lastly…

• November 11, 2005: Intel Makes Global WiMax Investment

• ZDNet reports that Intel released a slew of money around the

world for WiMax development: This includes a $1.12 billion contract for a project in Taiwan, which will agree to provide the

necessary spectrum for the work. The project will be

government-assisted until 2008 to bring businesses into the fold.

• The article says Intel has 13 more Europe and Americas networks up and running, with 10 more they’ve sponsored due to appear

by year’s end. This includes projects in The Dominican Republic

and Austria

Extra Slide


Page 9


The Future for WiMAX

• There are four end-game results for WiMAX:

1. The market share secured by non-WiMAX operators will be so large that WiMAX, in either its fixed or mobile value proposition, will simply not be able to get a foothold to deliver on the scale economics promised and will ultimately die or be relegated to niche applications such as wireless backhaul. This is a multi-standard outcome since multiple non-WiMAX standards might exist. (3G, Flash-OFDM and UMTS-TDD, 802.20)

2. The massive industry support for WiMAX and the technical superiority of the standard over some of the other mBWA technologies will encourage non-WiMAX operators to upgrade gradually to WiMAX, and new operators entering the market will automatically support WiMAX. This is a single standard outcome.

3. The existing non-WiMAX operators will continue to support their mBWA technologies while the new operator entrants will deploy WiMAX. This is a multi-standard outcome.

4. One of the non-WiMAX, proprietary standards sees a high level of early market traction and is able to establish itself as a de facto standard before WiMAX can gain any momentum. This is a single standard outcome.

Extra Slide

The above from IPWireless


Page 10


The WiMAX View

Extra Slide

WiMAX in Depth

Documents

Transcript of WiMAX in Depth