1. Wireless Application Protocol

2. Outline Mobile applications
How are mobile/wireless environments different?
What is WAP?
WAP Architecture
WAE (WML/WMLScript)
WTA Framework
WAP Push Services
WAP Protocol Stack
Hype v/s Reality
References and Resources

3. Mobile Applications - 1 Vehicles Emergencies Traveling salesmen
transmission of news, road condition etc
ad-hoc network with near vehicles to prevent accidents
Emergencies
early transmission of patient data to the hospital
ad-hoc network in case of earthquakes, cyclones
military ...
Traveling salesmen
direct access to central customer files
consistent databases for all agents
mobile office

4. Mobile Applications - 2 Web access Information services
outdoor Internet access
intelligent travel guide with up-to-date location dependent information
Information services
push: stock quotes; pull: nearest cash ATM
Disconnected operations
file-system caching for off-line work
mobile agents, e.g., shopping
Entertainment
games, etc

5. Variability of the Mobile Environment
Mobility
stationary
nomadic (pedestrian speed)
mobile (vehicular speed)
roaming (mobile across networks)
Connectivity
connected
semi-connected
(asymmetric)
weakly connected
disconnected
Mobile Device Capability
form factor
GUI
multimedia
real-time multimedia

6. World Wide Web and Mobility
HTTP/HTML have not been designed for mobile applications/devices
HTTP 1.0 characteristics
designed for large bandwidth, low delay
stateless, client/server, request/response communication
connection oriented, one connection per request
TCP 3-way handshake, DNS lookup overheads
big protocol headers, uncompressed content transfer
primitive caching (often disabled, dynamic objects)
security problems (using SSL/TLS with proxies)
HTML characteristics
designed for computers with “high” performance, color high-resolution display, mouse, hard disk
typically, web pages optimized for design, not for communication; ignore end-system characteristics

7. System Support for Mobile WWW
Enhanced browsers
client-aware support for mobility
Proxies
Client proxy: pre-fetching, caching, off-line use
Network proxy: adaptive content transformation for connections
Client and network proxy
Enhanced servers
server-aware support for mobility
serve the content in multiple ways, depending on client capabilities
New protocols/languages
WAP/WML

8. Wireless Application Protocol (WAP)
Empowers mobile users with wireless devices to easily access and interact with information and services.
A “standard” created by wireless and Internet companies to enable Internet access from a cellular phone
wapforum.org:
co-founded by Ericsson, Motorola, Nokia, Phone.com
450 members in 2000, comprise of Handset manufacturers, Wireless service providers, ISPs, Software companies in the wireless industry
Goals
deliver Internet services to mobile devices
enable applications to scale across a variety of transport options and device types
independence from wireless network standards
GSM, CDMA IS-95, TDMA IS-136, 3G systems (UMTS, W-CDMA)

9. WAP: Main Features Browser Markup language Script language Gateway
“Micro browser”, similar to existing web browsers
Markup language
Similar to HTML, adapted to mobile devices
Script language
Similar to Javascript, adapted to mobile devices
Gateway
Transition from wireless to wired world
Server
“Wap/Origin server”, similar to existing web servers
Protocol layers
Transport layer, security layer, session layer etc.
Telephony application interface
Access to telephony functions

10. Internet Model
HTML
HTTP
TLS/SSL
TCP/IP

11. WAP Architecture Web Server WAP Gateway Client HTTP WSP/WTP
Content
CGI
Scripts
etc.
with WML-Script
WML Decks
WAP Gateway
WML Encoder
WMLScript
Compiler
Protocol Adapters
Client
WML
WML-Script
WTAI
Etc.
HTTP
WSP/WTP
Source: WAP Forum

12. WAP Application Server
Client
WML
WML-Script
WTAI
Etc.
WAP Application Server
WML Encoder
WMLScript
Compiler
Protocol Adapters
Application
Logic
WSP/WTP
with WML-Script
WML Decks
Content
Source: WAP Forum

13. WAP Architecture Key Components Another look Origin/Web Server
WAP Gateway/Proxy
WAP Protocol Stack
Micro Browser
WML/WML Script
Transcoders
WTA
Source: WAP Forum

14. WAP: Network Elements fixed network wireless network Internet WAP
proxy
WML
Binary WML
HTML
filter
WML
HTML
HTML
filter/
WAP
proxy
Binary WML
web
server
HTML
WTA
server
Binary WML
PSTN
Binary WML: binary file format for clients
Source: Schiller

15. WAP Specifies Wireless Application Environment Wireless Protocol Stack
WML Microbrowser
WMLScript Virtual Machine
WMLScript Standard Library
Wireless Telephony Application Interface (WTAI)
WAP content types
Wireless Protocol Stack
Wireless Session Protocol (WSP)
Wireless Transport Layer Security (WTLS)
Wireless Transaction Protocol (WTP)
Wireless Datagram Protocol (WDP)
Wireless network interface definitions

16. WAP Stack Source: WAP Forum Runs on top of WDP
Provided lightweight X-oriented service
Unreliable 1-way request
Reliable 1-way/2-way req./response
MicroBrowser (WML, WMLScript, WTA, WTAI)
Lightweight SSL
Uses WIM/PKI-Cards
Datagram service on different bearers
Convergence between bearer services
Different Wireless Tech.
Source: WAP Forum

17. WAP Stack WAE (Wireless Application Environment):
Architecture: application model, browser, gateway, server
WML: XML-Syntax, based on card stacks, variables, ...
WTA: telephone services, such as call control, phone book etc.
WSP (Wireless Session Protocol):
Provides HTTP 1.1 functionality
Supports session management, security, etc.
WTP (Wireless Transaction Protocol):
Provides reliable message transfer mechanisms
Based on ideas from TCP/RPC
WTLS (Wireless Transport Layer Security):
Provides data integrity, privacy, authentication functions
Based on ideas from TLS/SSL
WDP (Wireless Datagram Protocol):
Provides transport layer functions
Based on ideas from UDP
Content encoding, optimized for low-bandwidth channels, simple devices

18. WHY WAP? Wireless networks and phones WAP
have specific needs and requirements
not addressed by existing Internet technologies
WAP
Enables any data transport
TCP/IP, UDP/IP, GUTS (IS-135/6), SMS, or USSD.
Optimizes the content and air-link protocols
Utilizes plain Web HTTP 1.1 servers
leverages existing development methodologies
utilizes standard Internet markup language technology (XML)
all WML content is accessed via HTTP 1.1 requests
WML UI components map well onto existing mobile phone user interfaces
no re-education of the end-users
leveraging market penetration of mobile devices
Several modular entities together form a fully compliant Internet entity

19. Why is HTTP/HTML not enough?
Big pipe - small pipe syndrome
Wireless network
<HTML>
<HEAD>
<TITLE>NNN Interactive</TITLE>
<META HTTP-EQUIV="Refresh" CONTENT="1800, URL=/index.html">
</HEAD>
<BODY BGCOLOR="#FFFFFF" BACKGROUND="/images/9607/bgbar5.gif" LINK="#0A3990" ALINK="#FF0000" VLINK="#FF0000" TEXT="000000" ONLOAD="if(parent.frames.length!=0)top.location='
<A NAME="#top"></A>
<TABLE WIDTH=599 BORDER="0">
<TR ALIGN=LEFT>
<TD WIDTH=117 VALIGN=TOP ALIGN=LEFT>
Internet
<WML>
<CARD>
<DO TYPE="ACCEPT">
<GO URL="/submit?Name=$N"/>
</DO>
Enter name:
<INPUT TYPE="TEXT" KEY="N"/>
</CARD>
</WML>
Content encoding
HTTP/HTML
WAP
Source: WAP Forum

20. WAP: “Killer” Applications
Location-based services
Real-time traffic reporting, Event/restaurant recommendation
Enterprise solutions
access, Database access, “global” intranet access
Information updates “pushed” to WAP devices
Financial services
Banking, Bill-paying, Stock trading, Funds transfers
Travel services
Schedules and rescheduling, Reservations
Gaming and Entertainment
Online, real-time, multi-player games
Downloadable horoscopes, cartoons, quotes, advice
M-Commerce
Shopping on the go
Instant comparison shopping
Location-based special offers and sales

21. Wireless Application Environment (WAE)
Goals
device and network independent application environment
for low-bandwidth, wireless devices
considerations of slow links, limited memory, low computing power, small display, simple user interface (compared to desktops)
integrated Internet/WWW programming model
high interoperability

22. WAE Components Architecture User Agents WML WMLScript WTA
Application model, Microbrowser, Gateway, Server
User Agents
WML/WTA/Others
content formats: vCard, vCalendar, Wireless Bitmap, WML, ...
WML
XML-Syntax, based on card stacks, variables, ...
WMLScript
procedural, loops, conditions, ... (similar to JavaScript)
WTA
telephone services, such as call control, text messages, phone book, ... (accessible from WML/WMLScript)
Proxy (Method/Push)

23. WAE: Logical Model Origin Servers Gateway Client Method proxy WTA
user agent
web
server
response
with
content
encoded
response
with
content
Push proxy
WML
user agent
other content
server
push
content
encoded
push
content
encoders
&
decoders
other
WAE
user agents
request
encoded
request

24. WAP Microbrowser Optimized for wireless devices
Minimal RAM, ROM, Display, CPU and keys
Provides consistent service UI across devices
Provides Internet compatibility
Enables wide array of available content and applications

25. WML: Wireless Markup Language
Tag-based browsing language:
Screen management (text, images)
Data input (text, selection lists, etc.)
Hyperlinks & navigation support
Takes into account limited display, navigation capabilities of devices
XML-based language
describes only intent of interaction in an abstract manner
presentation depends upon device capabilities
Cards and Decks
document consists of many cards
User interactions are split into cards
Explicit navigation between cards
cards are grouped to decks
deck is similar to HTML page, unit of content transmission
Events, variables and state mgmt
Content (XML)
XSL Processor
WML Browsers
WML Stylesheet
HTTP Browser
HTML StyleSheet

26. WML WML File Structure <?xml version="1.0"?>
The basic unit is a card. Cards are grouped together into Decks Document ~ Deck (unit of transfer)
All decks must contain
Document prologue
XML & document type declaration
<WML> element
Must contain one or more cards
WML File Structure
<?xml version="1.0"?>
<!DOCTYPE WML PUBLIC "-//WAPFORUM//DTD WML 1.0//EN"
"
<WML>
...
</WML>

27. WML Example Deck Card Navigation Variables Input Elements <WML>
<DO TYPE=“ACCEPT”>
<GO URL=“#eCard”/>
</DO
Welcome!
</CARD>
<CARD NAME=“eCard”>
<GO URL=“/submit?N=$(N)&S=$(S)”/>
</DO>
Enter name: <INPUT KEY=“N”/>
Choose speed:
<SELECT KEY=“S”>
<OPTION VALUE=“0”>Fast</OPTION>
<OPTION VALUE=“1”>Slow</OPTION>
<SELECT>
</WML>
Deck
Card
Navigation
Variables
Input
Elements

28. A Deck of Cards Acme Inc. Directory _____________ Next Services
<WML>
<CARD>
<DO TYPE="ACCEPT" LABEL="Next">
<GO URL="#card2"/>
</DO>
Acme Inc.<BR/>Directory
</CARD>
<CARD NAME="card2">
<DO TYPE="ACCEPT">
<GO URL="?send=$type"/>
Services
<SELECT KEY="type">
<OPTION VALUE="em"> </OPTION>
<OPTION VALUE="ph">Phone</OPTION>
<OPTION VALUE="fx">Fax</OPTION>
</SELECT>
</WML>
Acme Inc.
Directory
_____________
Next
Services
1>
2 Phone
____________ OK
Source: WAP Forum

29. The DO Element Binds a task to a user action
Action type: ACCEPT, OPTIONS, HELP PREV, DELETE, RESET
Label: Text string or image (optional)
Task: GO PREV, REFRESH, NOOP
Destination: URL
Post data: if METHOD=POST
<DO TYPE="ACCEPT" LABEL="Next">
<GO URL="
</DO>
Source: WAP Forum

30. Anchored Links
Bind a task to the ACCEPT action, when cursor points to a link
TITLE= sets the label string (default = “Link”)
Links are not allowed in select list options
<CARD>
Please visit our <A TITLE="Visit">
<GO URL="home.wml"/>home page</A>
for details.
</CARD>
Please visit our home page for
____________
Visit
Source: WAP Forum

31. The TEMPLATE Element Defines actions & events for all cards in a deck
<WML>
<TEMPLATE>
<DO TYPE="OPTIONS" LABEL="Main">
<GO URL="main_menu.wml"/>
</DO>
</TEMPLATE>
<CARD NAME="msg1">
<DO TYPE="ACCEPT" LABEL="Next">
<GO URL="#msg2"/>
First story
</CARD>
<CARD NAME="msg2">
Second story
</WML>
First story …
_____________
Next Main
Second story
...
_____________
OK Main
Source: WAP Forum

32. Handling User Input Select lists Input fields KEY variables
Choose from a list of options
Input fields
Enter a string of text or numbers
KEY variables
Set by SELECT and INPUT elements
How user input is passed to other cards and the application server
Source: WAP Forum

33. The SELECT Element Display a list of options
Each option may set the KEY variable and/or bind a task to the ACCEPT key
TITLE= dynamically sets the label string
MULTIPLE=“TRUE”: Allows user to pick multiple items
<CARD>
<DO TYPE="ACCEPT" LABEL="View">
<GO URL="getcity.cgi?location=$city"/>
</DO>
Forecast
<SELECT KEY="city">
<OPTION VALUE="ber">Berlin</OPTION>
<OPTION VALUE="rom">Rome</OPTION>
<OPTION TITLE="Find" ONCLICK="find.cgi">New City</OPTION>
</SELECT>
</CARD>
Forecast
1 Berlin
2 Rome
3>New City
____________
Find
Source: WAP Forum

34. The INPUT Element Prompts user to enter a string of text
DEFAULT=key_value; Default KEY variable (displayed to user)
FORMAT=format_specifier; If omitted, free-form entry is allowed
EMPTYOK="TRUE“; Browser will accept null input
TYPE="PASSWORD“; Special entry mode handled by the browser
MAXLENGTH=number; Maximum number of allowed characters
Soc. Security: _
____________
NUM
<CARD>
<DO TYPE="ACCEPT">
<GO URL="?get=person"
METHOD="POST" POSTDATA="userid=$ssn"/>
</DO>
Soc Security:
<INPUT KEY="ssn" FORMAT="NNN\-NN\-NNNN"/>
</CARD>
Soc. Security:
____________ OK
Source: WAP Forum

35. WML Content Formats Common interchange formats, for interoperability
Business cards: IMC vCard standard
Calendar: IMC vCalendar standard
Images: WBMP (Wireless BitMaP)
Compiled WML, WMLScript
Newly defined formats:
WML text and tokenized format
WMLScript text and bytecode format
WBMP image format
Binary format for size reduction
Bytecodes/tokens for common values and operators
Compressed headers
Data compression (e.g. images)
General-purpose transport compression can still be applied

36. Displaying Images Insert app images or local icons within display text
1-bit BMP format
Images are ignored by non-bitmapped devices
Check HTTP_ACCEPT for “image/bmp”
<CARD>
<DO TYPE="ACCEPT">
<GO URL="#c2"/>
</DO>
Continue <IMG LOCALSRC="righthand"
ALT="forward..."/>
</CARD>
<CARD NAME="c2">
<IMG SRC="../images/logo.wbmp"
ALT="Unwired Planet"/>
<BR/>Welcome!
Source: WAP Forum

37. WML (other features) Setting card styles to create forms
Using variables to cache user data
Using card intrinsic events to trigger transparent tasks
Using timers
Securing WML decks
Bookmarking decks

38. WMLScript Complement to WML Provides general scripting capabilities
Derived from JavaScript™
Provides general scripting capabilities
Procedural logic, loops, conditionals, etc.
Optimized for small-memory, small-cpu devices
Features
local user interaction, validity check of user input
access to device facilities (phone call, address book etc.)
extensions to the device software
configure device, download new functionality after deployment
Bytecode-based virtual machine
Stack-oriented design, ROM-able
Designed for simple, low-impact implementation
WMLScript compiler resides in the network

39. WMLScript Libraries
Lang - VM constants, general-purpose math functionality, etc.
String - string processing functions
URL - URL processing
Browser - WML browser interface
Dialog - simple user interface
Float - floating point functions

40. WMLScript Example Functions Variables Programming Constructs
function currencyConvertor(currency, exchRate) {
return currency*exchangeRate; }
function myDay(sunShines) {
var myDay;
if (sunShines) {
myDay = “Good”;
} else {
myDay = “Not so good”; };
return myDay;
Variables
Programming
Constructs
Source: WAP Forum

41. Wireless Telephony Application (WTA)
Collection of telephony specific extensions
designed primarily for network operators
Example
calling a number (WML) wtai://wp/mc;
calling a number (WMLScript) WTAPublic.makeCall(" ");
Implementation
Extension of basic WAE application model
Extensions added to standard WML/WMLScript browser
Exposes additional API (WTAI)

42. WTA Features Extension of basic WAE application model WTAI includes:
network model for interaction
client requests to server
event signaling: server can push content to the client
event handling
table indicating how to react on certain events from the network
client may now be able to handle unknown events
telephony functions
some application on the client may access telephony functions
WTAI includes:
Call control
Network text messaging
Phone book interface
Event processing
Security model: segregation
Separate WTA browser
Separate WTA port

43. WTA Example (WML) Placing an outgoing call with WTAI: WTAI Call
<CARD>
<DO TYPE=“ACCEPT”>
<GO URL=“wtai:cc/mc;$(N)”/>
</DO>
Enter phone number:
<INPUT TYPE=“TEXT” KEY=“N”/>
</CARD>
</WML>
WTAI Call
Input Element
Source: WAP Forum

44. WTA Example (WMLScript)
Placing an outgoing call with WTAI:
function checkNumber(N) {
if (Lang.isInt(N))
WTAI.makeCall(N);
else
Dialog.alert(“Bad phone number”); }
WTAI Call
Source: WAP Forum

45. WTA Logical Architecture
other telephone networks
WTA Origin Server
WTA & WML
server
WML Scripts
WML
decks
WTA
services
Client
WAE
services
WTA
user agent
mobile
network
WAP Gateway
encoders
&
decoders
network operator
trusted domain
other WTA
servers
third party origin servers
firewall
Source: Schiller

46. WTA Framework Components
Source: Heijden

47. WTA User Agent WTA User Agent WTA User Agent Context
WML User agent with extended functionality
can access mobile device’s telephony functions through WTAI
can store WTA service content persistently in a repository
handles events originating in the mobile network
WTA User Agent Context
Abstraction of execution space
Holds current parameters, navigation history, state of user agent
Similar to activation record in a process address space
Uses connection-mode and connectionless services offered by WSP
Specific, secure WDP ports on the WAP gateway

48. WTA Events and Repository
Network notifies device of event (such as incoming call)
WTA events map to device’s native events
WTA services are aware of and able to act on these events
example: incoming call indication, call cleared, call connected
WTA Repository
local store for content related to WTA services (minimize network traffic)
Channels: define the service
content format defining a WTA service stored in repository
XML document specifying eventid, title, abstract, and resources that implement a service
Resources: execution scripts for a service
could be WML decks, WML Scripts, WBMP images..
downloaded from WTA server and stored in repository before service is referenced
Server can also initiate download of a channel

49. WTA Channels and Resources
Source: Heijden

50. WTA Interface (public)
generic, high-level interface to mobile’s telephony functions
setting up phone calls, reading and writing entries in phonebook..
Public WTAI
for third party WML content providers
restricted set of telephony functions available to any WAE User Agent
library functions
make call: allows application to setup call to a valid tel number
send DTMF tones: send DTMF tones through the setup call
user notified to grant permission for service execution
cannot be triggered by network events
example: Yellow pages service with “make call” feature

51. WTA Interface (network)
Network Common WTAI
WTA service provider is in operator’s domain
all WTAI features are accessible, including the interface to WTA events
library functions
Voice-call control: setup call, accept, release, send DTMF tones
Network text: send text, read text, remove text (SMS)
Phonebook: write, read, remove phonebook entry
Call logs: last dialed numbers, missed calls, received calls
Miscellaneous: terminate WTA user agent, protect context
user can give blanket permission to invoke a function
example: Voice mail service
Network Specific WTAI
specific to type of bearer network
example:
GSM: call reject, call hold, call transfer, join multiparty, send USSD

52. WTA Event Handling Event occurrence Event handling Event binding
WTA user agent could be executing and expecting the event
WTA user agent could be executing and a different event occurs
No service is executing
Event handling
channel for each event defines the content to be processed upon reception of that event
Event binding
association of an event with the corresponding handler (channel)
Global binding:
channel corresponding to the event is stored in the repository
event causes execution of resources defined by the channel
example: voice mail service
Temporary binding:
resources to be executed are defined by the already executing service
example: yellow pages lookup and call establishment

53. Event Handling (no service in execution)
Source: Heijden

54. Event Handling (service already execution)
1: Temporary binding exists 2. No temporary binding and context is protected 3: No temporary binding and context is not protected
Source: Heijden

55. WTA: Voice mail Example
push deck
WTA client
WTA server
mobile network
voice mail server
incoming voice
message
generate
new deck
display deck;
user selects
translate
setup call
wait for call
accept call
voice connection
indicate new voice message
request
play requested voice message
call indication
Source: Schiller

56. WTA Application: Example (using WML)
<CARD>
<DO TYPE="ACCEPT" TASK="GO" URL="#voteChamp"/>
Please vote for your champion!
</CARD>
<CARD NAME="voteChamp">
<DO TYPE="ACCEPT" TASK="GO" URL="wtai://cc/sc;$voteNo;1"/>
Please choose:
<SELECT KEY="voteNo">
<OPTION VALUE=" ">Mickey</OPTION>
<OPTION VALUE=" ">Donald</OPTION>
<OPTION VALUE=" ">Pluto</OPTION>
</SELECT>
</WML>
Source: Schiller

57. WTA: Example with WML and WMLScript
function voteCall(Nr) {
var j = WTACallControl.setup(Nr,1);
if (j>=0) {
WMLBrowser.setVar("Message", "Called");
WMLBrowser.setVar("No", Nr); }
else {
WMLBrowser.setVar("Message", "Error!");
WMLBrowser.setVar("No", j);
WMLBrowser.go("showResult");
Source: Schiller

58. WTA: Example with WML and WMLScript
<CARD>
<DO TYPE="ACCEPT" TASK="GO" URL="#voteChamp"/>
Please vote for your champion!
</CARD>
<CARD NAME="voteChamp">
<DO TYPE="ACCEPT" TASK="GO" URL="/script#voteCall($voteNo)"/>
Please choose:
<SELECT KEY="voteNo">
<OPTION VALUE=" ">Mickey</OPTION>
<OPTION VALUE=" ">Donald</OPTION>
<OPTION VALUE=" ">Pluto</OPTION>
</SELECT>
<CARD NAME="showResult">
Status of your call: $Message $No
</WML>
Source: Schiller

59. WAP Push Services Web push Wireless push WAP push
Scheduled pull by client (browser)
example: Active Channels
no real-time alerting/response
example: stock quotes
Wireless push
accomplished by using the network itself
example: SMS
limited to simple text, cannot be used as starting point for service
example: if SMS contains news, user cannot request specific news item
WAP push
Network supported push of WML content
example: Alerts or service indications
Pre-caching of data (channels/resources)

60. WAP Push Framework
Source: Heijden

61. Push Access Protocol Based on request/response model
Push initiator is the client
Push proxy is the server
Initiator uses HTTP POST to send push message to proxy
Initiator sends control information as an XML document, and content for mobile (as WML)
Proxy sends XML entity in response indicating submission status
Initiator can
cancel previous push
query status of push
query status/capabilities of device

62. Push Proxy Gateway WAP stack (communication with mobile device)
TCP/IP stack (communication with Internet push initiator)
Proxy layer does
control information parsing
content transformation
session management
client capabilities
store and forward
prioritization
address resolution
management function

63. Over the Air (OTA) Protocol
Extends WSP with push-specific functionality
Application ID uniquely identifies a particular application in the client (referenced as a URI)
Connection-oriented mode
client informs proxy of application IDs in a session
Connectionless mode
well known ports, one for secure and other for non-secure push
Session Initiation Application (SIA)
unconfirmed push from proxy to client
request to create a session for a specific user agent and bearer

64. WAE Summary WML WMLScript WTA Push
analogous to HTML (optimized for wireless)
event based, microbrowser user agent
WMLScript
analogous to JavaScript
features of compiler in the network
WTA
WTAI: different access rights for different applications/agents
WTA User Agent (analogy with operating systems)
Context – Activation Record
Channel – Interrupt Handler
Resource – Shared routines invoked by interrupt handlers
Repository – Library of interrupt handlers
feature of dynamically pushing the interrupt handler before the event
Push
no analogy in Internet

65. WAP Gateway Summary Encoders Filters Method Proxy Push Proxy
translate between binary (WML) and text (HTML/WML)
Filters
transcoding between WML (wireless) and HTML (wired)
Method Proxy
similar to standard proxy services
WAP stack on wireless interface and TCP/IP stack on Internet interface
Push Proxy
Push Access Protocol with Internet Push Initiator (Web Server)
Over the Air Protocol with mobile device (and WAP Push Initiator)
Performs necessary filtering, translation etc.

66. WAP Servers Summary Origin Server WAP Server WTA Server
Web server with HTML/WML contents
Runs TCP/IP stack, needs PAP protocol for push, no end-to-end security
WAP Server
Serves WML content
Runs WAP stack, uses OTA protocol for push, end-to-end security possible
WTA Server
Specialized for telephony applications (runs WAP stack, uses push extensively)
Client initiated (make call “hyperlink” from a Yellow pages service)
Server intiated (incoming call from a Voice mail service)

67. WAP: Protocol Stack Bearers (GSM, CDPD, ...) Security Layer (WTLS)
Session Layer (WSP)
Application Layer (WAE)
Transport Layer (WDP)
TCP/IP,
UDP/IP,
media
SSL/TLS
HTML, Java
HTTP
Internet
WAP
WAE comprises WML (Wireless Markup Language), WML Script, WTAI etc.
Transaction Layer (WTP)
additional services and applications
WCMP
A-SAP
S-SAP
TR-SAP
SEC-SAP
T-SAP
Source: Schiller

68. WDP: Wireless Datagram Protocol
Goals
create a worldwide interoperable transport system by adapting WDP to the different underlying technologies
transmission services, such as SMS in GSM might change, new services can replace the old ones
WDP
Transport layer protocol within the WAP architecture
uses the Service Primitive
T-UnitData.req .ind
uses transport mechanisms of different bearer technologies
offers a common interface for higher layer protocols
allows for transparent communication despite different technologies
addressing uses port numbers
WDP over IP is UDP/IP

69. WDP: Service Primitives
T-SAP
T-DUnitdata.req (DA, DP, SA, SP, UD)
T-DUnitdata.ind (SA, SP, UD)
T-DError.ind (EC)
SAP: Service Access Point
DA: Destination Address
DP: Destination Port
SA: Source Address
SP: Source Port
UD: User Data
EC: Error Code
Source: Schiller

70. Service, Protocol, and Bearer Example
WAP Over GSM Circuit-Switched
RAS - Remote Access Server
IWF - InterWorking Function
WSP
WAE
Subnetwork IP
Apps on
Other Servers
WAP Proxy/Server
CSD-RF
PPP
Mobile
IWF
PSTN
Circuit
ISP/RAS
WTP
UDP
Any bearer which supports IP will be able to support WTP since WTP/T and in future WTP/C is defined for operation over UDP. The WTP/D service is UDP/IP.
Note: UDP will require a new port number to be issued/reserved by IANA for WAP. After which the suite of WAP protocols will be distinguished by port numbers or protocol identifiers defined by the WAP Forum within the WAP UDP port number issued by IANA.
Source: WAP Forum

71. Service, Protocol, and Bearer Example
WAP Over GSM Short Message Service
WAP Proxy/Server
Mobile
WAE
WAE
Apps on
other servers
WSP
WSP
SMSC
WTP
WTP
WDP
WDP
SMS
SMS
WDP Tunnel Protocol
WDP Tunnel
Protocol
Subnetwork
Subnetwork
under development
Source: WAP Forum

72. WTLS:Wireless Transport Layer Security
Goals
Provide mechanisms for secure transfer of content, for applications needing privacy, identification, message integrity and non-repudiation
Provide support for protection against denial-of-service attacks
WTLS
is based on the TLS/SSL (Transport Layer Security) protocol
optimized for low-bandwidth communication channels
provides
privacy (encryption)
data integrity (MACs)
authentication (public-key and symmetric)
Employs special adapted mechanisms for wireless usage
Long lived secure sessions
Optimised handshake procedures
Provides simple data reliability for operation over datagram bearers

73. WTLS Internal Architecture
Record Protocol
Handshake Protocol
Alert Protocol
Application Protocol
Change Cipher Spec Protocol
Transaction Protocol (WTP)
Datagram Protocol (WDP/UDP)
Bearer networks
WTLS
Record protocol
Note to translator:
Here I am going to explain and talk about each of the protocol elements in the WTLS layer
Source: WAP Forum

74. WTLS: Secure session, Full handshake
SEC-Create.req
(SA, SP, DA, DP, KES, CS, CM)
SEC-Create.ind
originator
SEC-SAP
peer
SEC-Create.cnf
(SNM, KR, SID, KES‘, CS‘, CM‘)
SEC-Create.res
SEC-Exchange.req
SEC-Exchange.ind
SEC-Exchange.res
(CC)
SEC-Commit.req
SEC-Exchange.cnf
SEC-Commit.ind
SEC-Commit.cnf
KES: Key Exchange Suite
CS: Cipher Suite
CM: Compression Mode
SNM: Sequence Number Mode
KR: Key Refresh Cycle
SID: Session Identifier
CC: Client Certificate
Source: Schiller

75. WTLS: Transferring Datagrams
sender
SEC-SAP
receiver
SEC-SAP
SEC-Unitdata.req
(SA, SP, DA, DP, UD)
SEC-Unitdata.ind
(SA, SP, DA, DP, UD)
Source: Schiller

76. WTP: Wireless Transaction Protocol
Goals
different transaction services that enable applications to select reliability, efficiency levels
low memory requirements, suited to simple devices (< 10kbyte )
efficiency for wireless transmission
WTP
supports peer-to-peer, client/server and multicast applications
efficient for wireless transmission
support for different communication scenarios
class 0: unreliable message transfer
unconfirmed Invoke message with no Result message
a datagram that can be sent within the context of an existing Session
class 1: reliable message transfer without result message
confirmed Invoke message with no Result message
used for data push, where no response from the destination is expected
class 2: reliable message transfer with exactly one reliable result message
confirmed Invoke message with one confirmed Result message
a single request produces a single reply

77. WTP Services and Protocols
WTP (Transaction)
provides reliable data transfer based on request/reply paradigm
no explicit connection setup or tear down
optimized setup (data carried in first packet of protocol exchange)
seeks to reduce 3-way handshake on initial request
supports
header compression
segmentation /re-assembly
retransmission of lost packets
selective-retransmission
port number addressing (UDP ports numbers)
flow control
message oriented (not stream)
supports an Abort function for outstanding requests
supports concatenation of PDUs
supports User acknowledgement or Stack acknowledgement option
acks may be forced from the WTP user (upper layer)
default is stack ack
Since there is no connection setup phase there is no mechanism to negotiate parameters (actually some things can be negotiated but not in the full sense that a connection-oriented call setup would allow) to be used during the message exchange, such as packet size or window size (packet group). Therefore using WTP/T requires an a priori agreement between the mobile and server as to the default parameters to be used during a message exchange.
Packet versus Streams
-a packet interface allows the application more control over a partial transmission. It requires the application (Session layer) to segment its transmission data to fixed length packets, this allows the restarting of a failed transmission at the place of the last successful transmission - checkpointing.
-a stream interface is what is most commonly implemented for TCP (sockets) and is widely used by TCP applications.

78. WTP Services and Protocols
uses the service primitives
T-TRInvoke.req .cnf. .ind .res
T-TRResult.req .cnf .ind .res
T-Abort.req .ind
Client
Server
Invoke
Ack
Result
T-TRInvoke.req
T-TRResult.ind
T-TRInvoke.cnf
T-TRResult.res
(PDUs)
T-TRInvoke.ind
T-TRResult.req
T-TRInvoke.res
T-TRResult.cnf
Ack may be piggybacked on a Result packet, therefore the Ack is shown with a dotted line.

79. WTP Class 0 Transaction initiator TR-SAP responder TR-SAP
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=0, H)
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=0, H‘)
Invoke PDU
A: Acknowledgement Type (WTP/User)
C: Class (0,1,2)
H: Handle (socket alias)
Source: Schiller

80. WTP Class 1 Transaction, no user ack & user ack
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=1, H)
Invoke PDU
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=1, H‘)
initiator
TR-SAP
responder
Ack PDU
TR-Invoke.cnf
(H)
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=1, H)
Invoke PDU
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=1, H‘)
initiator
TR-SAP
responder
Ack PDU
TR-Invoke.res
(H‘)
TR-Invoke.cnf
(H)
Source: Schiller

81. WTP Class 2 Transaction, no user ack, no hold on
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=2, H)
Invoke PDU
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=2, H‘)
initiator
TR-SAP
responder
Result PDU
TR-Result.req
(UD*, H‘)
TR-Result.ind
(UD*, H)
Ack PDU
TR-Invoke.cnf
(H)
TR-Result.res
TR-Result.cnf
(H‘)
Source: Schiller

82. WTP Class 2 Transaction, user ack
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=2, H)
Invoke PDU
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=2, H‘)
initiator
TR-SAP
responder
Result PDU
TR-Result.ind
(UD*, H)
Ack PDU
TR-Invoke.res
(H‘)
TR-Invoke.cnf
(H)
TR-Result.req
(UD*, H‘)
TR-Result.res
TR-Result.cnf
Source: Schiller

83. WTP Class 2 Transaction, hold on, no user ack
TR-Invoke.req
(SA, SP, DA, DP, A, UD, C=2, H)
Invoke PDU
TR-Invoke.ind
(SA, SP, DA, DP, A, UD, C=2, H‘)
initiator
TR-SAP
responder
Result PDU
TR-Result.req
(UD*, H‘)
TR-Result.ind
(UD*, H)
Ack PDU
TR-Invoke.cnf
(H)
TR-Result.res
TR-Result.cnf
(H‘)
Source: Schiller

84. WSP - Wireless Session Protocol
Goals
HTTP 1.1 functionality
Request/reply, content type negotiation, ...
support of client/server transactions, push technology
key management, authentication, Internet security services
WSP Services
provides shared state between client and server, optimizes content transfer
session management (establish, release, suspend, resume)
efficient capability negotiation
content encoding
push
WSP/B (Browsing)
HTTP/1.1 functionality - but binary encoded
exchange of session headers
push and pull data transfer
asynchronous requests

85. HTTP 1.1 and WSP HTTP 1.1 WSP enhancements beyond HTTP Why Not HTTP?
extensible request/reply methods
extensible request/reply headers
content typing
composite objects
asynchronous requests
WSP enhancements beyond HTTP
binary header encoding
session headers
confirmed and non-confirmed data push
capability negotiation
suspend and resume
fully asynchronous requests
connectionless service
Why Not HTTP?
encoding not compact enough, inefficient capability negotiation
no push facility

86. WSP Overview Header Encoding Capabilities (are defined for):
compact binary encoding of headers, content type identifiers and other well-known textual or structured values
reduces the data actually sent over the network
Capabilities (are defined for):
message size, client and server
protocol options: Confirmed Push Facility, Push Facility, Session Suspend Facility, Acknowledgement headers
maximum outstanding requests
extended methods
header code pages
Suspend and Resume
server knows when client can accept a push
multi-bearer devices
dynamic addressing
allows the release of underlying bearer resources

87. WSP Sessions Session Context and Push Connection-mode
push can take advantage of session headers
server knows when client can accept a push
Connection-mode
long-lived communication, benefits of the session state, reliability
Connectionless-mode
stateless applications, no session creation overhead, no reliability overhead

88. WSP/B session establishment
client
S-SAP
server
S-SAP
S-Connect.req
(SA, CA, CH, RC)
S-Connect.ind
(SA, CA, CH, RC)
Connect PDU
S-Connect.res
(SH, NC)
S-Connect.cnf
(SH, NC)
ConnReply PDU
CH: Client Header
RC: Requested Capabilities
SH: Server Header
NC: Negotiated Capabilities
WTP Class 2
transaction
Source: Schiller

89. WSP/B session suspend/resume
client
S-SAP
server
S-SAP
S-Suspend.req
S-Suspend.ind
(R)
Suspend PDU
S-Suspend.ind
(R)
WTP Class 0
transaction ~ ~
R: Reason for disconnection
S-Resume.req
(SA, CA)
S-Resume.ind
(SA, CA)
Resume PDU
S-Resume.res
Reply PDU
S-Resume.cnf
WTP Class 2
transaction
Source: Schiller

90. WSP/B session termination
client
S-SAP
server
S-SAP
S-Disconnect.req
(R)
S-Disconnect.ind
(R)
Disconnect PDU
S-Disconnect.ind
(R)
WTP Class 0
transaction
Source: Schiller

91. WSP/B method invoke client S-SAP server S-SAP S-MethodInvoke.req
(CTID, M, RU)
S-MethodInvoke.ind
(STID, M, RU)
Method PDU
S-MethodInvoke.res
(STID)
S-MethodInvoke.cnf
(CTID)
S-MethodResult.req
(STID, S, RH, RB)
S-MethodResult.ind
(CTID, S, RH, RB)
Reply PDU
S-MethodResult.res
(CTID)
S-MethodResult.cnf
(STID)
CTID: Client Transaction ID
M: Method Invoked
RU: Request URI
STID: Server Transaction ID
S: Response Status
RH: Response Header
RB: Response Body
WTP Class 2
transaction
Source: Schiller

92. WSP/B over WTP - method invocation
client
S-SAP
initiator
TR-SAP
responder
TR-SAP
server
S-SAP
S-MethodInvoke.req
TR-Invoke.req
Invoke(Method)
TR-Invoke.ind
S-MethodInvoke.ind
TR-Invoke.res
S-MethodInvoke.res
Ack PDU
S-MethodInvoke.cnf
TR-Invoke.cnf
TR-Result.req
S-MethodResult.req
Result(Reply)
S-MethodResult.ind
TR-Result.ind
S-MethodResult.res
TR-Result.res
Ack PDU
TR-Result.cnf
S-MethodResult.cnf
Source: Schiller

93. WSP/B over WTP - asynchronous, unordered requests
client
S-SAP
server
S-SAP
S-MethodInvoke_1.req
S-MethodInvoke_2.req
S-MethodInvoke_2.ind
S-MethodInvoke_1.ind
S-MethodInvoke_3.req
S-MethodResult_1.req
S-MethodInvoke_3.ind
S-MethodResult_1.ind
S-MethodResult_3.req
S-MethodResult_3.ind
S-MethodResult_2.req
S-MethodInvoke_4.req
S-MethodInvoke_4.ind
S-MethodResult_4.req
S-MethodResult_4.ind
S-MethodResult_2.ind
Source: Schiller

94. WSP/B - confirmed/non-confirmed push
client
S-SAP
server
S-SAP
S-Push.req
(PH, PB)
S-Push.ind
(PH, PB)
Push PDU
WTP Class 0
transaction
PH: Push Header
PB: Push Body
SPID: Server Push ID
CPID: Client Push ID
client
S-SAP
server
S-SAP
S-ConfirmedPush.req
(SPID, PH, PB)
S-ConfirmedPush.ind
(CPID, PH, PB)
ConfPush PDU
S-ConfirmedPush.res
(CPID)
S-ConfirmedPush.cnf
(SPID)
WTP Class 1
transaction
Source: Schiller

95. WSP/B over WDP client S-SAP server S-SAP S-Unit-MethodInvoke.req
(SA, CA, TID, M, RU)
S-Unit-MethodInvoke.ind
(SA, CA, TID, M, RU)
Method PDU
S-Unit-MethodResult.req
(CA, SA, TID, S, RH, RB)
S-Unit-MethodResult.ind
(CA, SA, TID, S, RH, RB)
Reply PDU
S-Unit-Push.req
(CA, SA, PID, PH, PB)
S-Unit-Push.ind
(CA, SA, PID, PH, PB)
Push PDU
WDP Unitdata
service
Source: Schiller

96. WAP Stack Summary WDP WTLS WTP WSP
functionality similar to UDP in IP networks
WTLS
functionality similar to SSL/TLS (optimized for wireless)
WTP
Class 0: analogous to UDP
Class 1: analogous to TCP (without connection setup overheads)
Class 2: analogous to RPC (optimized for wireless)
features of “user acknowledgement”, “hold on”
WSP
WSP/B: analogous to http 1.1 (add features of suspend/resume)
method: analogous to RPC/RMI
features of asynchronous invocations, push (confirmed/unconfirmed)

97. WAP: Ongoing Work WDP WTLS WTP WSP WAE
Tunnel to support WAP where no (end-to-end) IP bearer available
WTLS
support for end-to-end security (extending WTLS endpoint beyond WAP Gateway)
interoperable between WAP and Internet (public key infrastructure)
integrating Smart Cards for security functions
WTP
efficient transport over wireless links (wireless TCP)
bearer selection/switching
quality of service definitions
WSP
quality of service parameters
multicast data, multimedia support
WAE
User agent profiles: personalize for device characteristics, preferences etc
Push architecture, asynchronous applications
Billing

98. WAP: Hype vs Reality Low-bandwidth wireless links
tcp/ip over wireless can also address these problems
encoding in http can also reduce data transfer on wireless links
Limited device capabilities
Microbrowser is appropriate to address this problem
WTAI features are not present in tcp/ip domain
Challenges in WAP
adapting to applications rich in content and interaction
service guarantees
interface design and usability
Other approaches for WWW access through mobiles
i-Mode (from NTT DoCoMo)
WAP is a TRAP (

99. References and Resources
Books
Mobile communications: Jochen Schiller, Addison Wesley 2000
Understanding WAP:
Official Website (specifications)
Technical/Developer Info and tools
Major players
phone.com
OpenSource effort
(Kannel WAP gateway project)

100. Thank You This presentation is available online from
Sridhar Iyer
KR School of Information Technology
IIT Bombay

101. Is for “Wireless Fidelity” Or IEEE 802.11 Standard
WiFi
Is for “Wireless Fidelity” Or
IEEE Standard
WiFi

102. What is the goal of 802.11 standard ?
To develop a Medium Access Control (MAC) and Physical Layer (PHY) specification for wireless connectivity for fixed, portable and moving stations within a local area.
WiFi

103. 802.11 sub-standards(amendments ) ….
MAC (Media Access Control) ratified 1999
802.11b PHY 2.4 GHz (max 11 Mbps) ratified 1999
802.11a PHY 5.0 GHz (max 54 Mbps) ratified 1999
802.11g PHY 2.0 GHz (max 54 Mbps) ratified 2003
802.11i Security draft number XXX
802.11e QoS, Multimedia draft number XXX
802.11h European regulations for 5GHz draft number XXX
802.11h Japan regulations for 5GHz draft number XXX
WiFi

104. Do I need any license to use 802.11 device ?
No , 2.4 GHz and 5.0 GHz are public available frequency !!!
WiFi

105. Context with OSI layers
WiFi

106. Logical Link Control Services
WiFi

107. Standard frame format
WiFi

108. Frames types and subtypes
Three types of frames:
Control
(ACK,RTS,CTS ,Power Save …)
Management
(Beacon,Probe Request ,Probe Response,
Association request , Association response …)
Data
(Data, Null Data, Data_CF_Ack , ….)
WiFi

109. Infrastructure Model includes: (most common) Stations (STA)
MAC – Configuration summary – Infrastructure model
Infrastructure Model includes:
(most common)
Stations (STA)
any wireless device
Access Point (AP)
connects BSS to DS
controls access by STA’s
Basic Service Set (BSS)
a region controlled by an AP
mobility is supported within a single BSS
Extended Service Set (ESS)
a set of BSS’s forming a virtual BSS
mobility is supported between BSS’s in an ESS
Distribution Service (DS)
connection between BSS’s
BSS2
ESS1 DS
AP2
AP3
AP1
STA3
STA1
BSS3
BSS1
STA2
WiFi

110. The 802.11 MAC supports infrastructure and ad hoc network models
Ad Hoc Model includes:
Stations (STA)
any wireless device
act as distributed AP
Independent Basic Service Set (IBSS)
BSS forming a self contained network
no AP and no connection to the DS
STA1
STA3
STA2
IBSS
WiFi

111. Two types of access to air
DCF (distributed coordination function )
means everybody can speak and try
to get air : 100% on the market
PCF (point coordination function)
means ONE point coordinator (BOSS)
who will allowed you to speak
(like in bluetooth)
WiFi

112. Summary of required features and difficulties vs 802.11 features
High speed operation (PHY only)
Fair access (DCF, PCF)
Time-bounded access (PCF)
Flexible configuration (BSS, IBSS)
Security (WEP)
Mobility support (ESS)
Low power (PS)
Difficulties
Hidden terminals (RTS/CTS)
Capture (CSMA/CA, ACK)
Noise and interference (ACK, frag)
Limited spectrum (licencing, PHYs)
WiFi

113. The MAC basic Distributed Co-ordination Function (DCF) access scheme uses a CSMA/CA based protocol
If the STA detects the medium is busy when attempting to send a packet then:
the STA starts a random back-off timer
the randomisation parameters depend on previous transmission successes/failures
the back-off timer runs once the medium has been idle for an IFS period
An STA may transmit a packet after sensing the medium is idle for an Inter Frame Space (IFS) period
the back-off timer suspends when the medium is busy and does not restart until medium is idle for an IFS period
The STA may transmit when the back-off timer expires
The state (busy or idle) of the medium is determined using:
physical carrier sense
virtual carrier sense, based on reservations in received packets. These reservations set the NAV timer. The medium is considered busy until the NAV timer expires
WiFi

114. The MAC basic Distributed Co-ordination Function (DCF) access scheme uses a CSMA/CA based protocol
Medium busy
Contention window
Send frame
IFS
IFS
Busy
Frame
Defer access while busy and for an IFS period
Decrement back-off when medium idle for at least IFS period
WiFi

115. Acknowledgment
WiFi

116. Security WEP ( wired equivalent privacy) 64/128 bits
Using RC4 algorithm, almost permanent key, very week
security, able to crack by collecting statistic
Current security level for 99.9% products on the market.
TKIP (temporal key integrity protocol )
Used RC4 algorithm with with a 128-bit "temporal key"
but changes temporal keys every 10,000 packets and key dependes on address and sequence number.
Will be required to obtain WiFi certification from 09/01/03
AES (Advanced Encryption Standard )
New, much more stronger encryption, protect against hacker frames in insertion. Need hardware accelerator. Optional feature.
WiFi

117. Why do we need 11A/11B/11G ? 11B: 2.4 GHz , CCK modulation
Rates from 1 to 11Mbps , on market from 1999
11A: 5.0 GHz , OFDM modulation
Rates from 6 to 56 Mbps , on market from 2002
11G: 2.4 GHz, CCK+OFDM modulation
Rates from 6 to 56 Mbps, on market from and …
most popular today !!!
Advantages of 2.4 GHz PHY:
Low frequency, better wall penetration, less sensitive to multipath
3 not-overlapped channels
Advantages of 5.0 GHz PHY:
Less devices on the market (no microwave, no blue tooth …)
8 not-overlapped channels
Range: almost the same …
WiFi

118. a/b/g performance 11A/G max throughput ~22 Mbps , not 54 Mbps (!!!) 11B max throughput ~6 Mbps
WiFi

119. Wlan market Scenarios
WiFi

120. IEEE 802.16 for MAN==Metropolitan Area Network New alternative to DSL/Cable modems
IEEE Progress
Work on started in July Four years into its mission, the IEEE Working Group on Broadband Wireless Access has delivered a base and three follow-on standards.
IEEE (“Air Interface for Fixed Broadband Wireless Access Systems”) was approved in December This standard is for wireless MANs operating at frequencies between 10 and 66 GHz.
IEEE , published in 2001, specifies a “recommended practice” to address the operation of multiple, different broadband systems in the GHz frequency range.
In January of this year, the IEEE approved an amendment to , called a, which adds to the original standard operation in licensed and unlicensed frequency bands from 2-11 GHz.
802.16c, which was approved in December 2002, is aimed at improving interoperability by specifying system profiles in the GHz range.
WiFi

121. 802.11/802.16
WiFi

122. WiFi

123. WiFi

124. WiFi

125. What is WIMAX ?
WiMAX is an IP based, wireless broadband access technology that provides performance similar to /Wi-Fi networks with the coverage and QOS (quality of service) of cellular networks. WiMAX is also an acronym meaning "Worldwide Interoperability for Microwave Access (WiMAX).

126. What is WIMAX ?
WiMAX (Worldwide Interoperability for Microwave Access) is a telecommunications protocol that provides fixed and mobile Internet access. The current WiMAX revision provides up to 40 Mbit/s with the IEEE m update expected to offer up to 1 Gbit/s fixed speeds.

127. What is WIMAX ?
The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard. The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL".

128. What is last mile operation ?
The "last mile" or "last kilometer" is the final leg of delivering connectivity from a communications provider to a customer. The phrase is therefore often used by the telecommunications and cable television industries. The actual distance of this leg may be considerably more than a mile, especially in rural areas.

129. What is last mile operation ?
It is typically seen as an expensive challenge because "fanning out" wires and cables is a considerable physical undertaking. Because the last mile of a network to the user is also the first mile from the user to the world, the term "first mile" is sometimes used.

130. Last mile
To solve the problem of providing enhanced services over the last mile, some firms have been mixing networks for decades. One example is Fixed Wireless Access, where a wireless network is used instead of wires to connect a stationary terminal to the wireline network.

131. What is Wimax ?
WiMAX is a wireless digital communications system, also known as IEEE , that is intended for wireless "metropolitan area networks". WiMAX can provide broadband wireless access (BWA) up to 30 miles (50 km) for fixed stations, and miles ( km) for mobile stations. In contrast, the WiFi/ wireless local area network standard is limited in most cases to only feet ( m).

132. Integration with an IP-based network

133. Integration with an IP-based network
The WiMAX Forum has proposed an architecture that defines how a WiMAX network can be connected with an IP based core network, which is typically chosen by operators that serve as Internet Service Providers (ISP); Nevertheless the WiMAX BS provide seamless integration capabilities with other types of architectures as with packet switched Mobile Networks.

134. Integration with an IP-based network
The WiMAX forum proposal defines a number of components, plus some of the interconnections (or reference points) between these, labeled R1 to R5 and R8:
SS/MS: the Subscriber Station/Mobile Station
ASN: the Access Service Network[19]
BS: Base station, part of the ASN
ASN-GW: the ASN Gateway, part of the ASN
CSN: the Connectivity Service Network
HA: Home Agent, part of the CSN
AAA: Authentication, Authorization and Accounting Server, part of the CSN
NAP: a Network Access Provider
NSP: a Network Service Provider

135. Integration with an IP-based network
It is important to note that the functional architecture can be designed into various hardware configurations rather than fixed configurations. For example, the architecture is flexible enough to allow remote/mobile stations of varying scale and functionality and Base Stations of varying size - e.g. femto, pico, and mini BS as well as macros.

136. WiMAX installation
There are numerous devices on the market that provide connectivity to a WiMAX network. These are known as the "subscriber unit" (SU).
There is an increasing focus on portable units. This includes handsets (similar to cellular smartphones); PC peripherals (PC Cards or USB dongles); and embedded devices in laptops, which are now available for Wi-Fi services.

137. WiMAX installation
In addition, there is much emphasis by operators on consumer electronics devices such as Gaming consoles, MP3 players and similar devices. It is notable that WiMAX is more similar to Wi-Fi than to 3G cellular technologies.

138. WiMAX installation
The WiMAX Forum website provides a list of certified devices. However, this is not a complete list of devices available as certified modules are embedded into laptops, MIDs (Mobile Internet devices), and other private labeled devices.

139. WiMAX installation: Gateways
WiMAX gateway devices are available as both indoor and outdoor versions from several manufacturers. Many of the WiMAX gateways that are offered by manufactures such as Airspan, ZyXEL, Huawei, Motorola, and Greenpacket are stand-alone self-install indoor units. Such devices typically sit near the customer's window with the best WiMAX signal, and provide:

140. WiMAX installation: Gateways
An integrated Wi-Fi access point to provide the WiMAX Internet connectivity to multiple devices throughout the home or business.
Ethernet ports should you wish to connect directly to your computer or DVR instead.
One or two PSTN telephone jacks to connect your land-line phone and take advantage of VoIP.

141. WiMAX installation: Gateways
Indoor gateways are convenient, but radio losses mean that the subscriber may need to be significantly closer to the WiMAX base station than with professionally-installed external units.
Outdoor units are roughly the size of a laptop PC, and their installation is comparable to the installation of a residential satellite dish. A higher-gain directional outdoor unit will generally result in greatly increased range and throughput but with the obvious loss of practical mobility of the unit.

142. WiMAX installation: Dongles
There are a variety of USB dongles on the market which provide connectivity to a WiMAX network. Generally these devices are connected to a notebook or netbook whilst on the go. Dongles typically have omnidirectional antennae which are of lower-gain compared to other devices, as such these devices are best used in areas of good coverage.

143. WiMAX installation: Mobile phones
HTC announced the first WiMAX enabled mobile phone, the Max 4G, on Nov 12th 2008.[12] The device was only available to certain markets in Russia on the Yota network.

144. WiMAX installation: Mobile phones
HTC and Sprint Nextel released the second WiMAX enabled mobile phone, the EVO 4G, March 23, 2010 at the CTIA conference in Las Vegas. The device, made available on June 4, 2010,[13] is capable of both EV-DO(3G) and WiMAX(4G) as well as simultaneous data & voice sessions. The device also has a front-facing camera enabling the use of video conversations.[14] A number of WiMAX Mobiles are expected to hit the US market in 2011.

145. WiMAX installation: MAC (data link) layer
The WiMAX MAC uses a scheduling algorithm for which the subscriber station needs to compete only once for initial entry into the network. After network entry is allowed, the subscriber station is allocated an access slot by the base station. The time slot can enlarge and contract, but remains assigned to the subscriber station, which means that other subscribers cannot use it.

146. WiMAX installation: MAC (data link) layer
In addition to being stable under overload and over-subscription, the scheduling algorithm can also be more bandwidth efficient. The scheduling algorithm also allows the base station to control Quality of service (QoS) parameters by balancing the time-slot assignments among the application needs of the subscriber station.

147. WiMAX Performance
As a standard intended to satisfy needs of next-generation data networks (4G), WiMAX is distinguished by its dynamic burst algorithm modulation adaptive to the physical environment the RF signal travels through. Modulation is chosen to be more spectrally efficient (more bits per OFDM/SOFDMA symbol).

148. WiMAX Performance
That is, when the bursts have a high signal strength and a high carrier to noise plus interference ratio (CINR), they can be more easily decoded using digital signal processing (DSP).

149. WiMAX Performance
In contrast, operating in less favorable environments for RF communication, the system automatically steps down to a more robust mode (burst profile) which means fewer bits per OFDM/SOFDMA symbol; with the advantage that power per bit is higher and therefore simpler accurate signal processing can be performed.

150. WiMAX vs. LTE
The more recent Long Term Evolution (LTE) standard is a similar term describing a parallel technology to WiMAX that is being developed by vendors and carriers as a counterpoint to WiMAX.

151. An example of Wireless competition
Korea launched Wimax at 2nd quarter of 2006 and then launched HSPA one quarter after launched Wimax. At the end of 2008 there were 8.4 million HSPA subscribers and 350,000 Wimax subscribers in Korea. Almost all of HSPA subscribers come from 2G and 3G users who have been tempted to upgrade to new devices by high subsidies, whereas Wimax subscribers almost all are newcomers.

152. An example of wireless competition
Deployment of Wimax is still limited (spotted), whereas there are well over 100 countries where HSPA networks are deployed, and even where there is no HSPA coverage there is backward compatibility (using HSPA devices) to pre-existing networks (GSM and WCDMA) with a roaming infrastructure already in place

153. WiMAX statistics
As of October 2010, the WiMAX Forum claims there are over 592 WiMAX (fixed and mobile) networks deployed in over 148 countries.
Yota is the largest WiMAX network operator in the world, but has announced that it will move new network deployments to LTE and, subsequently, change its existing networks as well.

154. What is HSPA ?
High Speed Packet Access (HSPA) is an amalgamation of two mobile telephony protocols, High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA), that extends and improves the performance of existing WCDMA protocols. A further standard, Evolved HSPA (also known as HSPA+), was released late in 2008 with subsequent adoption worldwide beginning in 2010.

155. WiMAX competitors
Within the marketplace, WiMAX's main competition comes from existing, widely deployed wireless systems such as UMTS, CDMA2000, existing Wi-Fi and mesh networking.

156. WiMAX competitors
Speed vs. Mobility of wireless systems: Wi-Fi, HSPA, UMTS, GSM

157. The future of wireless networks
In the future, competition will be from the evolution of the major cellular standards to so-called 4G, high-bandwidth, low-latency, all-IP networks with voice services built on top. The worldwide move to 4G for GSM/UMTS and AMPS/TIA (including CDMA2000) is the 3GPP Long Term Evolution effort.