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Wireless Application Protocol

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Presentation on theme: "Wireless Application Protocol"— Presentation transcript:

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 co-founded by Ericsson, Motorola, Nokia, 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)

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 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

106 Logical Link Control Services

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.

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