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WLAN-IEEE802.11 Tutorial (Maximilian Riegel), 021018-wlan-tutorial.ppt

Page 32

© Siemens, 2002

DIFS

Contention Window

Slot time

'HIHU$FFHVV

Backoff-Window

Next Frame

6HOHFW6ORWDQG'HFUHPHQW%DFNRIIDVORQJDVPHGLXPLVLGOH

SIFS

PIFS

DIFS

Free access when medium

is free longer than DIFS

Busy Medium

CSMA/CA Explained

n

Reduce collision probability where mostly needed.

– Stations are waiting for medium to become free.
– Select Random Backoff after a Defer, resolving contention 

to avoid collisions.

n

Efficient Backoff algorithm stable at high loads.

– Exponential Backoff window increases for 

retransmissions.

– Backoff timer elapses only when medium is idle.

n

Implement different fixed priority levels

IFS: Inter Frame Space

Summary of Contents for IEEE802.11

Page 1: ...Maximilian Riegel ICM Networks Advanced Standardization ...

Page 2: ...et everywhere n WLAN is more than just cable replacement it provides hassle free broadband Internet access everywhere n Coverage in hot spots sufficient n IEEE802 11b meets the expectations for easiness cost and bandwidth Public WLAN Airport Railway Station Campus Plant Semi public WLAN Office Hospital Congress hall Hotel Corporate WLAN Office Home WLAN Remote Access ...

Page 3: ...e been started All big players have products Cisco Intel Integrated WLAN solutions appearing Apple IBM n The prediction have been exceeded by actual market For comparison Total PC world market in 01 120 Mio pcs 30 portable n Ruling technology is IEEE802 11b Wi Fi 11Mb s 2 4 GHz 0 5 10 15 20 25 98 99 00 01 02 1 UI L I PLR Source Frost Sullivan 2000 03 ...

Page 4: ...002 Outline n Part 1 Wireless Internet System Architecture n Part 2 IEEE802 11 Overview n Part 3 Physical Layer n Part 4 Medium Access Control n Part 5 MAC Layer Management n Part 6 WLAN Mobility n Part 7 WLAN Security n Part 8 Public Hotspot Operations n Part 9 WLAN UMTS Interworking ...

Page 5: ...s 2002 Part 1 Wireless Internet system architecture n Generic Internet network architecture n Layering means encapsulation n IEEE802 11 seamless integration into the Internet n IP based network architecture n Wireless LAN IEEE802 11 basic architecture n What is unique about wireless ...

Page 6: ...6 Siemens 2002 Internet Web Applications Generic Internet network architecture link phy ip tcp http www link phy ip link phy ip link phy ip link phy ip 802 2 link phy ip 802 2 ip tcp http www Peer Client Peer Web Server 802 2 802 3 ip 802 2 802 3 3ROLF 6HUYHU 6HUYHU 1 FFHVV ...

Page 7: ...pt Page 7 Siemens 2002 user data appl header tcp header application data ip header Ethernet ip header tcp header appl header user data HTML http tcp ip 802 2 TCP segment IP datagramm Ethernet frame 64 1500 bytes 14 bytes 20 bytes 20 bytes Layering means encapsulation ...

Page 8: ...ximilian Riegel 021018 wlan tutorial ppt Page 8 Siemens 2002 IEEE802 11 seamless integration into the Internet KWPO PO VO VPLO 773 73 6073 16 6103 7 3 6 60 70 6 1 1 6 8 3 HQFDS 333 53 W3C IETF ITU ETSI ATMF 6 73 0 8 3 QWHUQHW www ...

Page 9: ...ip ip N DATA request N DATA indication N DATA N DATA N DATA ip connectionless non reliable end to end packet oriented data delivery service 193 175 26 92 131 34 3 35 Version Length Type of Service Total Length Identification 6 Fragment offset Time to live Protocol Header checksum Source IP Address 32bit Destination IP Address 32 bit Options if any 1 2 3 4 Data 0 0 R T D D Delay T Throughput R Reli...

Page 10: ...0 Siemens 2002 http tcp ip ppp Bluetooth Netscape ip 802 2 802 2 802 3 802 2 802 3 802 2 802 3 http tcp ip ppp Bluetooth apache ip 802 2 802 3 ip IEEE802 11 local distribution network internet Client Access Point Access Router Server Wireless LAN IEEE802 11 basic architecture ...

Page 11: ... space and time shared with unwanted 802 11 devices shared with non 802 devices unlicensed spectrum microwave ovens n Full connectivity cannot be assumed hidden node problem n Mobility variation in link reliability battery usage requires power management want seamless connections n Security no physical boundaries overlapping LANs n Multiple international regulatory requirements ...

Page 12: ...iegel 021018 wlan tutorial ppt Page 12 Siemens 2002 Part 2 IEEE802 11 Overview n Wireless IEEE802 11 Standard n IEEE802 11 Configurations n IEEE802 11 Architecture Overview n IEEE802 11 Protocol Architecture n Wireless LAN Standardization ...

Page 13: ...ope ETS 300 328 Japan RCR STD 33A n Supports three PHY layer types DSSS FHSS Infrared n MAC layer common to all 3 PHY layers n Robust against interference n Provides reliable efficient wireless data networking n Supports peer to peer and infrastructure configurations n High data rate extension IEEE802 11b with 11 Mbps using existing MAC layer Approved June 1997 802 11b approved September 1999 ...

Page 14: ...ions n Independent one Basic Service Set BSS Ad Hoc network direct communication limited coverage area n Infrastructure Access Points and stations Distribution System interconnects Multiple Cells via Access Points to form a single Network extends wireless coverage area Station Station Station Station A1 A2 B1 B2 BSS A BSS B A AP AP B Server DISTRIBUTION SYSTEM ...

Page 15: ...nsfer data on a shared medium without reservation data comes in bursts user waits for response so transmit at highest speed possible is the same service as used by Internet n Isochronous Service reserve the medium for a single connection and provide a continues stream of bits even when not used works only when cells using the same frequencies are not overlapping n Robust against noise and interfer...

Page 16: ...t handover MAC MIB n MAC Entity basic access mechanism fragmentation encryption n PHY Layer Management channel tuning PHY MIB n Physical Layer Convergence Protocol PLCP PHY specific supports common PHY SAP provides Clear Channel Assessment signal carrier sense n Physical Medium Dependent Sublayer PMD modulation and encoding MAC Sublayer PLCP Sublayer PMD Sublayer MAC Layer Management PHY Layer Man...

Page 17: ...tandardization topics HiperLAN 2 DFS TPC 5 GHz 54 Mbit s ETSI BRAN 8076 QWHJUDWLRQ 802 11f Inter Access Point Protocol IEEE 802 11 IEEE 802 11 2 4 GHz 2 Mbit s 802 11b 2 4 GHz 11Mbit s 802 11g 2 4 GHz 54Mbit s 802 11a 5 GHz 54Mbit s 802 11e 4R6 QKDQFHPHQWV 802 11i 6HFXULW QKDQFHPHQWV 802 11h DFS TPC WIG Wireless Interworking Group ...

Page 18: ...Hopping Spread Spectrum n Direct Sequence Spread Spectrum n DSSS Transmit Spectrum and Channels n IEEE802 11a 5GHz PHY Layer n IEEE802 11g Further Speed Extension for the 2 4 GHz Band n Spectrum Designation in the 5GHz range n IEEE802 11h Spectrum and Transmit Power Management n when will 5 GHz WLANs come n PHY Terminology n Physical Layer Convergence Protocol PLCP ...

Page 19: ...g frequencies of 1 MHz width US Frequency Power Frequency Power spreading n 2 4 GHz Direct Sequence Spread Spectrum DBPSK DQPSK with 1 2 Mbps Spreading with 11 Bit barker Code 11 13 channels in the 2 4 GHz band n 2 4 GHz High Rate DSSS Ext 802 11b CCK DQPSK with 5 5 11 Mbps Frequency Power n 5 GHz OFDM PHY 802 11a Basic parameters identical to HiperLAN2 PHY European regulatory issues n Baseband IR...

Page 20: ... f5 Frequency Hopping Spread Spectrum n 2 4GHz band is 83 5MHz wide US Europe n Band is divided into at least 75 channels n Each channel is 1MHz wide n Transmitters and receivers hop in unison among channels in a pseudo random manner n Power must be filtered to 20db at band edge ...

Page 21: ...nd signal after spreading Transmitter baseband signal before spreading Receiver baseband signal after matched filter De spread Receiver baseband signal before matched filter Correlator RF Energy is Spread by XOR of Data with PRN Sequence Signal Spectrum 1 0 1011011100010110111000 PRN Pseudorandom Number Direct Sequence Spread Spectrum ...

Page 22: ...ppt Page 22 Siemens 2002 DSSS Transmit Spectrum and Channels fc fc 11 MHz fc 22 MHz Sinx x fc 11 MHz fc 22 Mhz 0 dBr 30 dBr 50 dBr Unfiltered Transmit Spectrum Mask DQQHO 86 76 DSDQ 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 0 0 1 1 0 1 1 0 1 1 1 0 ...

Page 23: ...ers Sub carrier modulation BPSK QPSK 16QAM 64QAM Bit interleaved convolutional coding K 7 R 1 2 2 3 3 4 OFDM frame duration 4µs guard interval 0 8ms 18MHz channel spacing 9 10 channels in 200MHz bandwidth n Key milestones First letter ballot by working group from November 1998 meeting January 1999 joint meeting with ETSI BRAN ...

Page 24: ...d n Mandatory CCK w short preample 802 11b and OFDM 802 11a applied to 2 4 GHz range n Optional PBCC proposal for 22 Mbit s from Texas Instruments n Optional CCK OFDM proposal for up to 54 Mbit s from Intersil Range vs throughput rate comparison of n CCK 802 11b n OFDM 802 11a n PBCC n CCK OFDM Batra Shoemake Texas Instruments Doc 11 01 286r2 ...

Page 25: ...2002 UHT XURSH 86 DSDQ QGRRU P 2XWGRRU 53 2XWGRRU 53 0D SHDN 7 SRZHU 2XWGRRU 53 QGRRU P 53 0D PHDQ 7 SRZHU 6 73 6 73 6 QDPLF UHTXHQF 6HOHFWLRQ 73 7UDQVPLW 3RZHU RQWURO Spectrum Designation in the 5 GHz range n Many European countries are currently opening the 5 GHz range for radio LANs ...

Page 26: ...tion power consumption reduction range control and link robustness TPC procedures include AP s define and communicate regulatory and local transmit power constraints Stations select transmit powers for each frame according to local and regulatory constraints AP 1 AP 2 AP 3 STA n DFS Dynamic Frequency Selection AP s make the decision STA s provide detailed reports about spectrum usage at their loca...

Page 27: ...QoS despite many applications do not need QoS at all network issues access control and handover n 5 GHz systems will be used when the 2 4 GHz ISM band will become too overcrowded to provide sufficient service TCP IP based applications are usually very resilient against error proune networks n Issues of 5 GHz systems Cost 5 GHz is more expensive than 2 4 GHz Power 7dB more transmission power for sa...

Page 28: ...rthogonal Frequency Division Multiplex n PPM Pulse Position Modulation n GFSK Gaussian Frequency Shift Keying n DBPSK Differential Binary Phase Shift Keying n DQPSK Differential Quadrature Phase Shift Keying n CCK Complementary Code Keying n PBCC Packet Binary Convolutional Coding n QAM Quadrature Amplitude Modulation ...

Page 29: ...LCP n SYNC gain setting energy detection antenna selection frequency offset compensation n SFD Start Frame Delimiter bit synchronization n SIGNAL rate indication 1 2 5 5 11 Mbit s n SERVICE reserved for future use n LENGTH number of octets in PSDU n CRC CCITT CRC 16 protects signal service length field PLCP Protocol Data Unit ...

Page 30: ...Features n CSMA CA Explained n CSMA CA ACK protocol n Distributed Coordination Function DCF n Hidden Node Provisions n IEEE802 11e MAC Enhancements for Quality of Service EDCF n Point Coordination Function PCF n IEEE802 11e MAC Enhancements for Quality of Service HCF n Frame Formats n Address Field Description n Summary MAC Protocol Features ...

Page 31: ...sed on Carrier Sense function in PHY called Clear Channel Assessment CCA n Robust for interference CSMA CA ACK for unicast frames with MAC level recovery CSMA CA for Broadcast frames n Parameterized use of RTS CTS to provide a Virtual Carrier Sense function to protect against Hidden Nodes Duration information is distributed by both transmitter and receiver through separate RTS and CTS Control Fram...

Page 32: ...ium is free longer than DIFS Busy Medium CSMA CA Explained n Reduce collision probability where mostly needed Stations are waiting for medium to become free Select Random Backoff after a Defer resolving contention to avoid collisions n Efficient Backoff algorithm stable at high loads Exponential Backoff window increases for retransmissions Backoff timer elapses only when medium is idle n Implement...

Page 33: ...fer DIFS SIFS DIFS CSMA CA ACK protocol n Defer access based on Carrier Sense CCA from PHY and Virtual Carrier Sense state n Direct access when medium is sensed free longer then DIFS otherwise defer and backoff n Receiver of directed frames to return an ACK immediately when CRC correct When no ACK received then retransmit frame after a random backoff up to maximum limit ...

Page 34: ...erral Distributed inter frame deferral Distributed inter frame deferral Random back off Random back off ACK to STA1 Short interval ensures ACK is sent while other stations wait longer Tx Data STA 3 s back off is shorter than STA 4 s therefore it begins transmission first HWHFWV FKDQQHO EXV HWHFWV FKDQQHO EXV Detects channel busy HWHFWV FKDQQHO EXV Distributed Coordination Function DCF ...

Page 35: ... other STA B STA A RTS Range Access Point CTS Range RTS CTS STA A AP STA B DIFS STA B cannot detect carrier from STA A Next MPDU Time period to defer access is based on duration in CTS Back off after defer Ack Data Solution Optional use of the Duration field in RTS and CTS frames with AP Hidden Node Provisions ...

Page 36: ...fic categories 4 different traffic categories output queue competes for TxOPs using EDCF wherein the minimum specified idle duration time is a distinct value the contention window is a variable window lower priority queues defer to higher priority queues n EDCF Enhanced Distributed Coordination Function Mapping to Access Category Transmit Queues Per queue channel access functions with internal col...

Page 37: ... Coordination Function PCF n Optional PCF mode provides alternating contention free and contention operation under the control of the access point n The access point polls stations for data during contention free period n Network Allocation Vector NAV defers the contention traffic until reset by the last PCF transfer n PCF and DCF networks will defer to each other n PCF improves the quality of ser...

Page 38: ...coordinator hybrid coordinator by default collocated with the enhanced access point QAP uses the point coordinator s higher priority to allocate transmission opportunities TxOPs to stations meets predefined service rate delay and or jitter requirements of particular traffic flows n HCF Hybrid coordination function Caused long delays in standardization process due to its complexity Recently widely ...

Page 39: ...ody 2 2 6 6 6 6 2 0 2312 4 802 11 MAC Header Bytes Protocol Version Type SubType To DS Retry Pwr Mgt More Data WEP Rsvd Bits 2 2 4 1 1 1 1 1 1 1 1 DS From More Frag Frame Formats n MAC Header format differs per Type Control Frames several fields are omitted Management Frames Data Frames n Includes Sequence Control Field for filtering of duplicate caused by ACK mechanism ...

Page 40: ...SSID N A 0 1 DA BSSID SA N A 1 0 BSSID SA DA N A 1 1 RA TA DA SA Address Field Description n Addr 1 All stations filter on this address n Addr 2 Transmitter Address TA Identifies transmitter to address the ACK frame to n Addr 3 Dependent on To and From DS bits n Addr 4 Only needed to identify the original source of WDS Wireless Distribution System frames ...

Page 41: ...nnel Assessment CCA function for CSMA CA n Robust for interference CSMA CA ACK for unicast frames with MAC level recovery CSMA CA for broadcast frames n Virtual carrier sense function provided to protect against hidden nodes n Includes fragmentation to cope with different PHY characteristics n Point Coordination Function PCF option for time bounded data n Frame formats to support multiple configur...

Page 42: ...Page 42 Siemens 2002 Part 5 MAC layer management n Infrastructure Beacon Generation n Timing Synchronization Function n Scanning n Active Scanning Example n Power Management Considerations n Power Management Approach n Power Management Procedure n MAC Management Frames ...

Page 43: ...edium Infrastructure Beacon Generation n APs send Beacons in infrastructure networks n Beacons scheduled at Beacon Interval n Transmission may be delayed by CSMA deferral subsequent transmissions at expected Beacon Interval not relative to last Beacon transmission next Beacon sent at Target Beacon Transmission Time n Timestamp contains timer value at transmit time ...

Page 44: ...redict start of Contention Free burst n Timing Synchronization Function TSF keeps timers from all stations in synch AP controls timing in infrastructure networks distributed function for Independent BSS n Timing conveyed by periodic Beacon transmissions Beacons contain Timestamp for the entire BSS Timestamp from Beacons used to calibrate local clocks not required to hear every Beacon to stay in sy...

Page 45: ...w AP while roaming initializing an Independent BSS ad hoc network n 802 11 MAC uses a common mechanism for all PHY single or multi channel passive or active scanning n Passive Scanning Find networks simply by listening for Beacons n Active Scanning On each channel Send a Probe Wait for a Probe Response n Beacon or Probe Response contains information necessary to join new network ...

Page 46: ...tial connection to an Access Point Reassociation follows a similar process Steps to Association Station sends Probe APs send Probe Response Station selects best AP Station sends Association Request to selected AP AP sends Association Response Access Point C Access Point A Active Scanning Example ...

Page 47: ...N protocols assume stations are always ready to receive Idle receive state dominates LAN adapter power consumption over time n How can we power off during idle periods yet maintain an active session n 802 11 Power Management Protocol allows transceiver to be off as much as possible is transparent to existing protocols is flexible to support different applications possible to trade off throughput f...

Page 48: ...nounces which stations have frames buffered Traffic Indication Map TIM sent with every Beacon n Power Saving stations wake up periodically listen for Beacons n TSF assures AP and Power Save stations are synchronized stations will wake up to hear a Beacon TSF timer keeps running when stations are sleeping synchronization allows extreme low power operation n Independent BSS also have Power Managemen...

Page 49: ...PS Poll Broadcast Power Management Procedure n Stations wake up prior to an expected DTIM Delivery Traffic Indication Message n If TIM indicates frame buffered station sends PS Poll and stays awake to receive data else station sleeps again n Broadcast frames are also buffered in AP all broadcasts multicasts are buffered broadcasts multicasts are only sent after DTIM DTIM interval is a multiple of ...

Page 50: ...es n Probe Response Timestamp Beacon Interval Capabilities ESSID Supported Rates pars same for Beacon except for TIM n Association Request Capability Listen Interval ESSID Supported Rates n Association Response Capability Status Code Station ID Supported Rates n Reassociation Request Capability Listen Interval ESSID Supported Rates Current AP Address n Reassociation Response Capability Status Code...

Page 51: ... Riegel 021018 wlan tutorial ppt Page 51 Siemens 2002 Part 6 WLAN Mobility n IEEE802 11 Ad Hoc Mode n IEEE802 11 Infrastructure Mode n Mobility inside a WLAN hotspot by link layer functions n IEEE802 11f Inter Access Point Protocol IAPP ...

Page 52: ...l ppt Page 52 Siemens 2002 Peer to Peer Network IEEE802 11 Ad Hoc Mode n Independent networking Use Distributed Coordination Function DCF Forms a Basic Service Set BSS Direct communication between stations Coverage area limited by the range of individual stations ...

Page 53: ...DS BSS B Server IEEE802 11 Infrastructure Mode n Access Points AP and stations STA n BSS Basic Service Set a set of stations controlled by a single coordination function n Distribution system interconnects multiple cells via access points to form a single network n Extends wireless coverage area and enables roaming ...

Page 54: ...WLRQ QHWZRUN n Station uses scanning function to find another AP or uses information from previous scans n Station sends Reassociation Request to new AP n If Reassociation Response is successful then station has roamed to the new AP else station scans for another AP n If AP accepts Reassociation Request normally old AP is notified through Distribution System AP indicates Reassociation to the Distr...

Page 55: ... tutorial ppt Page 55 Siemens 2002 IEEE802 11f Inter Access Point Protocol IAPP n IAPP defines procedures for context transfer between APs when stations move automatic configuration handling of access points Distribution System Server 33 029 33 5 86 6HUYHU ...

Page 56: ...ge 56 Siemens 2002 Part 7 WLAN security n IEEE802 11 Privacy and Access Control n WEP privacy mechanism n Shared key authentication n Shortcomings of plain WEP security n IEEE802 11i Robust Security Network RSN n A last word about WLAN security n Summary MAC Functionality ...

Page 57: ...de n 802 11 provides for an authentication mechanism To aid in access control Has provisions for OPEN Shared Key or proprietary authentication extensions n Shared key authentication is based on WEP privacy mechanism Limited for station to station traffic so not end to end Uses RC4 algorithm based on a 40 bit secret key and a 24 bit IV that is send with the data includes an ICV to allow integrity c...

Page 58: ...GHU 0 HDGHU 5 3D ORDG QFU SWHG 9 9 SKHUWH W QWHJULW OJRULWKP 3 351 9 9 6HFUHW H LSKHUWH W 9 3ODLQWH W 9 9 3ODLQWH W 7 9 LSKHUWH W 9 6HFUHW H 3 351 QWHJULW OJRULWKP WEP privacy mechanism n WEP bit in Frame Control Field indicates WEP used Each frame can have a new IV or IV can be reused for a limited time ...

Page 59: ... FKDOOHQJH WH W JHQHUDWHG ZLWK WKH 3 DOJRULWKP 6WDWLRQ HQFU SWV FKDOOHQJH WH W DQG VHQGV LW WR WKH 3 3 GHFU SWV WKH HQFU SWHG FKDOOHQJH WH W XWKHQWLFDWLRQ VXFFHVVIXO LI WH W PDWFKHV RULJLQDO Shared key authentication n Shared key authentication requires WEP n Key exchange is not specified by IEEE802 11 n Only one way authentication ...

Page 60: ...ay protection known plaintext attacks n No user authentication Only NICs are authenticated n No mutual authentication Only station is authenticated against access point n Missing key management protocol No standardized way to change keys on the fly Difficult to manage per user keys for larger groups n WEP is no mean to provide security for WLAN access but might be sufficient for casual uses ...

Page 61: ...ardware for higher security requirements or WRAP Wireless Robust Authenticated Protocol based on AES Advanced Encryption Standard and OCB Offset Codebook n Security association management RSN negotiation procedures for establishing the security context IEEE802 1X authentication and key management Associate EAP Identity Request EAP Identity Response EAP Request EAP Response EAP Success Access Reque...

Page 62: ...cient for public hot spots n Only VPN technologies IPSEC TLS SSL will fulfil end to end security requirements in public environments n VPN technologies might even be used in corporate WLAN networks http ip ppp Netscape ip 802 2 802 2 802 3 802 2 802 3 802 2 802 3 http ip ppp Bluetooth apache ip 802 2 802 3 ip WEP 802 11 tcp tcp 802 11 IPSEC TLS SSL tcp tcp ...

Page 63: ...n avoidance MAC level acknowledgment allows for RTS CTS exchanges hidden node protection MSDU fragmentation Point Coordination option AP polling n Association and Reassociation station scans for APs association handshakes Roaming support within an ESS n Power management support stations may power themselves down AP buffering distributed approach for IBSS n Authentication and privacy Optional suppo...

Page 64: ...otspot n Becoming a WLAN operator is easy n Selling WLAN access in public hot spots Probably to consider n Using a web page for initial user interaction n How does it work Web based access control n Web based access control Enabler for mCommerce and location based services n Functions of an integrated access gateway User Management n Functions of an integrated access gateway Network services ...

Page 65: ...21018 wlan tutorial ppt Page 65 Siemens 2002 Congress hall Hotel Airport Railway Station Campus Office Hospital á R QRW WRXFK FXVWRPHU HTXLSPHQW á GGUHVV DOO FXVWRPHUV á 0DNH DFFHVV SURFHGXUH VHOI H SODLQLQJ Serving customers in public hot spots ...

Page 66: ...que configuration n Only a very common dominator can be assumed for the software installations available on all notebooks n Most WLAN enabled notebooks will use DHCP for basic IP configuration n A web browser will likely be available on all notebooks Public WLAN Airport Railway Station Campus Plant Semi public WLAN Office Hospital Congress hall Hotel Corporate WLAN Office Home WLAN Remote Access ...

Page 67: ...viding telephony services not providing network access across borders of private premises n Cost issues The lower bound Investment WLAN Access Point w DSL Router 350 Monthly operation cost 60 IRU 6 ODW 5DWH Most commercial installations are much more expensive due to charging and billing n It is very easy and extremely cheap to become a WLAN operator but most people did not yet know about it but w...

Page 68: ...orial Maximilian Riegel 021018 wlan tutorial ppt Page 68 Siemens 2002 Selling WLAN access in public hot spots Probably to consider n How does your favorite storefront look like Too much security might hinder your business ...

Page 69: ... 11 Tutorial Maximilian Riegel 021018 wlan tutorial ppt Page 69 Siemens 2002 Authentication for Internet access Selection of billing method Free local content services Using a web page for initial user interaction ...

Page 70: ...torial Maximilian Riegel 021018 wlan tutorial ppt Page 70 Siemens 2002 How does it work Web based access control LQWHUQHW Password Username auth html RADIUS client auth 3 6HUYHU 6HUYHU FFHVV DWHZD 0RELOH OLHQW max riegel ...

Page 71: ...mCommerce application into a web page for WLAN access control enables further services to be billed there is far more business for the operator than just WLAN access n Due to its limited coverage services delivered by WLAN in hot spots can easily tailored to their locations Operators can start with location based services without huge investments for full geographic coverage ...

Page 72: ...ers based on External database supports ISP roaming via RADIUS Integrated LDAP directory GSM phone Transmission of one time passwords by SMS Credit card n Authorization based on user profiles assigned to different user groups having particular access Dynamic subscribtion to additional services Personalized portal page n Real time accounting based on service duration and volume Instant user feedbac...

Page 73: ... DHCP server for assigning IP addresses to WLAN clients Retaining session if user is temporarily out of WLAN coverage Detection of session end n Policy engine Loadable user profiles User specific routing configuration Dynamic firewalling rules n IP router with NAT engine Assignment of private addresses for free services Must allow IPSEC connections ...

Page 74: ...TS Interworking Ancient approach tight coupling n WLAN as an exension of a mobile network n WLAN is much cheaper than 2G 3G n Conclusions for Mobile Network Operators n WLAN UMTS Interworking Now widely accepted loose coupling n WLAN loosely coupled to a Mobile Network n E g Web based authentication and mobile network security n Standards for WLAN UMTS Interworking ...

Page 75: ...GSM GPRS UMTS n anytime everywhere n voice realtime messaging n QoS n precious bandwidth n carrier grade n operator driven n huge customer base n high revenues WLAN IEEE802 11 n sometimes somewhere n standard web applications n best effort n cheap bandwidth n corporate technology n market driven n casual users n low revenues ...

Page 76: ...M IP MSCS MSCS BTS BSC BTS Node B Node B RNC internet wlan local access network WLAN UMTS Interworking Ancient approach tight coupling WLAN as just another radio access technology of UMTS n All UMTS services become available over WLAN but n PLMN is burdened with high bandwidth WLAN traffic n Wi Fi does not provide all the functionality needed QoS security ...

Page 77: ...n of a mobile network n WLAN just as another radio access technology n MNOs are the WLAN operators OA M agreement with siteowner very dense PLMN n Full competition with open ISP market n Mobile network is carrier of the WLAN traffic n Dynamics of growth may differ n very complex SIM USIM cards required new standards necessary ...

Page 78: ...ch cheaper than 2G 3G based on current IP volume prices of 40 WH Time based pricing results in similar costs e g MobileStar Pulsar pricing plan 0 10 min 356 60 6 6 1 356 60 6 6 1 7UDQVIHU RVW Duration min ORJDULWKPLF VFDOH 99 6 Transfer cost duration of an 1 Mbytes ppt doc xls File 4 min 4 min 5 sec ...

Page 79: ...pealing task of a WLAN operator is charging and billing n MNOs have large customer bases secure authentication and accounting facilities and they like to go into mobile business n Providing electronic payment services to WLAN operators can be an important market entry into mobile business for MNOs n There is no time to wait The WLAN access market is exploding and WLAN access may be for free in man...

Page 80: ...rk WLAN UMTS Interworking Now widely accepted loose coupling Only Authentication Authorization and Accounting of WLAN access is performed by the mobile network operator n Revenues without competing against aggressive WLAN operators n Perfect model for leveraging the huge customer base and establishing a widely accepted platform for mobile commerce Authentication Accounting Siemens contributed loos...

Page 81: ...emens 2002 HLR SGSN SIM loose coupling SIM HLR RADIUS loose coupling RADIUS WLAN loosely coupled to a Mobile Network n Each hotspot is SS7 endpoint SIM cards required SGSN or MSC functionality at access network n Tight userbase to HLR Standalone capability Flexibility in security ...

Page 82: ...8 wlan tutorial ppt Page 82 Siemens 2002 mobile network HLR E g Web based authentication and mobile network security LQWHUQHW Password Username auth html RADIUS client auth 3 6HUYHU 6HUYHU FFHVV DWHZD 0RELOH OLHQW SMS containing Password 0172 3456789 ...

Page 83: ...rLAN 2 and 3rd generation cellular and other public systems Detailed architectural description mainly based on the Siemens loose coupling principle established IEEE802 11 and MMAC are now joining this effort Wireless Interworking Group WIG n WECA Wireless Ethernet Compatibility Alliance Wireless ISP Roaming Initiative Detailed functional specification for roaming loose coupling between IEEE802 11 ...

Page 84: ...k you for your attention n Questions and comments Maximilian Riegel maximilian riegel icn siemens de Literature n The IEEE 802 11 Handbook A Designer s Companion Bob O Hara Al Patrick IEEE press ISBN 0 7381 1855 9 n 802 11 Wireless Networks The Definitive Guide Matthew S Gast O Reilly ISBN 0 596 00183 5 ...

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