Bluetooth/WiFi/WiMAX Communications

Zulfiquar Sayeed Bell Labs Lucent Technologies [email protected] 732-949-3055

22 June 2005 The Big Picture

Personal Fixed Portable Mobile Unlicensed Licensed and Unlicensed Licensed and Unlicensed Licensed Broadband Device Connectivity Networking Wireless Services and Wideband Services

Device to Device to Campus Access & Zonal Nomadic Low Mobility Cellular Device Peripherals Networking Backhaul WAN

WPAN WPAN WiFi WiMAX WiFi WiMAX WiMAX 2.5G, 3GÆ 802.15 802.15.x 802.11 802.16d 802.11 802.16e 802.16e 802.20

CoverageWPAN < CoverageWLAN < CoverageWMAN < CoverageWWAN

Source: Intel Corp/ Modified 2 Zones of Interest of the IEEE

Internet Protocols

802.1 Bridging and Network Management 802.21 Handoff 802.2 Logical Link Control 802.15 802.11 802.16 MAC Wireless Wireless Wireless 802.3 802.20 + PAN LAN MAN Ethernet MBWA 802.16E PHY New TGs New TGs Mobility

2.5G 3G 802.20 Mobility 802.16e Oval heights signify coverage 802.11b 802.11a/g 802.16d 802.15.4 802.15.1 802.15.3 Throughput 10 to 200 kbps 200k to 1Mbps 1M to 10M 10M to 70M

3 802.15 Standardization

Project Standardized Modulation Coding Timing Data Rate Range Configuration Carrier

TDD / 625usec framing / Repetition, 802.15.1 Frequency Synchronous/ 8 master-slave 2001 Hamming, 1 MBPS 10m(I) 100m(III) (Bluetooth) hopped / Asynch piconet/scatter-net ARQ GMSK 1 MHz 2.4 to Channelization 2.4835 GHz ISM QPSK + 4/16/32QAM + Synchronous/ 22, 33, 44, 256 active device 802.15.3 2002 DQPSK 15 TCM / ARQ 30-50 m Asynch 55 MBPS piconet/mesh MHz Channelization

Master/Slave (256 868-868.6 BPSK/OQPSK; 10m nominal Synchronous/ 20, 40, devices or (1); 902-928 802.15.4 2003 Symbol to chip ARQ extensible to 100m Asynch 250 kbps more)/Mesh; Star; (10); 2400- mapping TDD based on settings Peer-Peer 2483.5 (16)

Monitoring, Control, Security Cable replacement: hands-free, printer hookup, gaming, digital film kiosk drop-offÆ imagination is the limit Harald I Bluetooth (Danish Harald Blåtand) was the King of Denmark between 940 and 985 AD. Bluetooth/ Blåtand had a dark complexion, hence blue. The good King Harald "united" Denmark and Norway Î Ericsson’s Name. 4 Bluetooth Network Architectures

Master

Slave

Master/Slave

Legend Piconet Scatternet

Piconet: ‰ WPAN formed by a Bluetooth device serving as a master and one or more devices serving as slaves ‰ Master transmits the beacon with parameters (This essentially defines Master, the responder, the Slave) ‰ Frequency-hopping channel based on address of the master ‰ Frequency-hopping synchronized using the clock of the master ‰ Slaves communicate only with master in a point-to-point fashion under the control of the master ‰ A slave device during one communications session could be a master in another. Scatternet: ‰ A collection of operational Bluetooth piconets overlapping in time and space ‰ Bluetooth device may participate in several piconets at the same time Æ allows information flow beyond the coverage area of a single piconet ‰ A device in a scatternet could be a slave in several piconets, but master in only one

5 802.15 Specification Scope

Not Specified but interfaces with Bluetooth Specs: ‰ RFCOMM: Serial cable emulation protocol ETSI TS 07.01 for legacy apps over Bluetooth support ‰ TCS: Telephony control protocol specification ‰ SDP: Service Discovery Protocol ‰ Other: Object Exchange Protocol (OBEX), the Point-to-Point Protocol (PPP), the Wireless Application Protocol (WAP), and so on

Std 802.15.1-2002

‰ Phy: Transmission, No Interpretation of data, RF conformance, Power, Modulation, Intermodulation ... ‰ BB: Circuit+Packet switching, synchronous/asynchronous, 64 kbps synchronous voice, Hopping, ARQ, FEC, Data Whitening, Parking/Unparking of Slaves ‰ Link Manager: Authentication, Link keys, Master/Slave role switching, Connection Detach, Sniff mode ↔ Active mode, Power Control, QoS (Master controlled Polling interval, Num of broadcast attempts) ‰ L2CAP: Support of SDP, TCS..., Protocol multiplexing, segmentation and reassembly, QoS monitoring, Grouping of addresses (Pico, scatternets)... 6 802.11 Specifications 802.11f: IAPP

802.11i: Security Enhancements 802.11e: QoS Specifications MAC IEEE 802.11

802.11n 2.4/5 GHz 802.11a 802.11g 802.11b PHY <100MBPS 5 GHz 2.4/5 GHz 2.4 GHz 2.4 GHZ < 54 MBPS < 54 MBPS < 11 MBPS 1&2 MBPS

Date Spec Carrier Modulation Data Rate 2.402-2.479; 1 MHz FHSS, 2 & 4 GMSK channelizization PHY+PLCP+ 802.11 1997 2.412-2.462; 11 1 & 2 MBPS MAC 11bit Barker Code Channels defined, 3 DSSS, DPSK, DQPSK useable CCK 4 or 8 bits in 8 2.412-2.462 GHz, 3 802.11b 1999 PHY Enh complex code out 5.5 or 11 MBPS Channels useful (walsh type)&PBCC 8 Channels in 5150 to 6, 9, 12, 18, 24, BPSK/QPSK/4/16/64 802.11a 1999 PHY Enh 5350 (16.6 MHz 36, 48, 54 QAM Channelization) MBPS DSSS 1 & 2 MBPS a & b PHY CCK 5.5 & 11 802.11g 2003 2.402-2.479 colsolidation OFDM 6...54 PBCC 5.5, 11, 22, 33 CCK: Complimentary Code Keying PBCC: Packet Binary Complimentary Coding IAPP: Inter Access Point Protocol

7 802.11 Applications Ethernet Link

AP

AP Hot Spots AP AP

AP AP AP AP

AP AP AP

Metropolitan City Wide Coverage Not Quite: ‰ Need to have the APs be the most common in use (a, b, g) ‰ Need to be able to handoff from AP to AP Æ Single frequency band of operation ‰ Need to perform some cell planning ‰ Backhaul costs will be inordinate Î Mesh Networks

8 Mesh Networking with 802.11

Ethernet Link 802.11b AP 802.11a AP AP 802.11a Ch1

802.11a Ch2 BH

AP AP AP

AP AP AP

Ad-Hoc Single Band Meshing: Ad-Hoc Dual Band Meshing: Dual Band Multi-Channel Meshing: ƒ Self configurable ƒ Self configurable ƒ Self configurable ƒ Self healing ƒ Self healing ƒ Self healing ƒ Select path ƒ Select best path ƒ Select best of all possible paths ƒ Quickly run out of capacity ƒ Unintentional contention in BH ƒ Controlled Frequency Planning in BH ƒ Unintentional contention in BH

Further Possibility: Service Network Overlaid with WWAN BH Network Î 802.16

9 WiMAX Applications 1 3 2 RESIDENTIAL & SoHo DSL FRACTIONAL T1 for LEVEL SERVICE 4 SMALL BUSINESS BACKHAUL for Mobile HOTSPOTS WMAN Nomadic Coverage --> Backhaul handoff from HOT SPOTS H H T1+ LEVEL SERVICE 802.16d 802.16d H ENTERPRISE H H H H H H

= wide area coverage 802.16e 5 outside of Hot Spots

INTERNET Wireless Local BACKBONE Loop in BWA Operator Network Developing Backbone Mobility 6 Nations

Source: Alvarion 10 Comparing 802.16d

Channel Standard bits/sec/ FDD/TDD DL Peak UL Peak Bandwidth Body hz GPRS 160 kbps 160 kbps 0.80 200 KHz FDD Edge 480 kbps 480 kbps 2.40 WCDMA FDD/TDD 2 Mbps 2 Mbps 3GPP 0.40 5 MHz HSDPA FDD 14.4 Mbps 7 Mbps 2.88 3G1X 640 kbps 450 kbps 0.51 EvDO 1.25 MHz FDD 3.1 Mbps 1.8 Mbps 3GPP2 2.48 EvDv 3.1 Mbps 1.8 Mbps 2.56 Normalized upto 75 802.16d upto 20 MHz FDD/TDD upto 75 Mbps IEEE Throughput Mbps 3.75 Comparison Flarion 1.25 MHz FDD 3.2 Mbps 900 kbps - 2.56

4.00 3.50 3.00 2.50 2.00 1.50 DL bits/sec/hz 1.00 0.50 0.00

Dv vDO v Edge 3G1X E E GPRS Flarion WCDMA HSDPA 802.16d

11 802.16 Specifications

802.16f: Management Information Blocks 802.16g: Mob. Mgmt. Plane Procedures and Services Network Mngmnt

802.16e 802.16-2001 Mobility TDM 802.16-2004 Enhancements: FDD/TDD (802.16d) MAC 802.16c Handoff/ ATM +Packet CS System ActiveSet/ 802.16b Profiles for Anchor cross- Target... manufacturer 802.16a Wireless- Conformance SCa HUMAN OFDM 256 PHY S-OFDMA: OFDM256 2048 / 1024 / 512 OFDMA 2048 / 128

2 to 6 GHz <11 GHz 10-66 GHz

NLOS NLOS LOS

15 MBPS <75MBPS <134 MBPS

Mobile Fixed Fixed 1.75 to 20 MHz 1.75 to 20 MHz 20/25/28 MHz

Worldwide Interoperability for Microwave Access: First products to be available in Dec 05 Deals with the OFDM/OFDMA branch of the 802.16 family

HIPERMAN – the parallel ETSI effort: Identical to 802.16a and 802.16d, except: Only OFDM PHY 12 802.16-2004 and 802.16e Profiles Single Carrier Operation OFDM Operation

MAC ATM/ Packet profM1/M2 WirelessMAN-OFDM MAC Packet(ATM nr) profM3 Duplexing TDD/FDD WirelessHUMAN-OFDM BE/nRTPS Full QoS B/W 25 MHz <11 GHz BW Duplexing profP1 Frame 1 ms PhyP3_175 1.75 MHz T/F Modulation Q/Q16 DL/Q UL PhyP3_35 3.5 MHz T/F WirelessMAN-SC 10-66 MHz Symbol Rate 20 MBd PhyP3_70 7.0 MHz T/F PhyP3_30 3.0 MHz T/F Duplexing TDD/FDD MOBILE PhyP3_55 5.5 MHz T/F B/W 28 MHz PhyP3_100 10. MHz T profP2 Frame 1 ms Modulation 2/4/16/64 Modulation Q/Q16 DL/Q UL Symbol Rate (BWMHz-0.88)/1.25 Symbol Rate 22.4 MBd FFTSize: 256

WIrelessMAN-OFDMA MAC Packet(ATM nr) OFDMA_profM1 WirelessHUMAN-OFDMA BE/nRTPS Full QoS Wi rel essMAN- SCa MAC ATM/Packet profM4/M5 <11 GHz PhyProfiles BW Duplexing WirelessHUMAN-Sca PhyP6-P8 BW Duplexing ofdma_profP1 1.25 MHz T <11 GHz 3.5 MHz F ofdma_profP2 3.5 MHz T/F 7.0 MHz F ofdma_profP3 7.0 MHz T/F 10. MHz Undefined ofdma_profP4 8.75 MHz T 20.0 MHz Undefined ofdma_profP5 14 MHz T/F ofdma_profP6 17.5 MHz T Frame 4 ms MOBILE ofdma_profP7 28 MHz T/F Modulation 2/4/16/64/256 ULDL ofdma_profP8 10 MHz T Symbol Rate (BWMHz-0.88)/1.25 ofdma_profP9 20 Mhz T Number SCs 1 to 32 Modulation 4/16/64. Symbol Rate (BWMHz-0.88)/1.25 FFTSize: D: 2048 / E: 2048/1024/512/128 (SOFDMA)

13 So What is LoS?

Tx Rx

3rd Fresnel Zone

2nd Fresnel Zone 1st Fresnel Zone λ N d 1 d 2 r F = 1 N + d 1 d 2 c1

Set N = 1, d1, d2 Î r1 Tx Rx

d1 d2

≥ c1 0.6 r1 : LOS c1 < 0.6 r1 : NLOS

14 OFDM Basics

TG TUseful 1/TUseful

f4

f3 f Frequency 2

f1

f0

DC Time Freq ƒ Signal is accessible in time and frequencyÎ Time variations and frequency variations can be coded/interleaved across Î Advanced Space-Time-Frequency Coding ƒ Guard Interval absorbs the designed multipath effects Î Single tap multiplicative equalizerÎ NLOS operation ƒ OFDMA: Single Frequency Network operation with reuse factor of 1 Î Planning benefit + Spectrum Utilization ƒ Invented at Bell Labs : Chang and Gibby, 1960s Î DVB-T, SDARs, WiFi, WiMax, HiperLAN/MAN, DAB, DSL and coming in EvDO, UMTS! 9 R.W. Chang [1966], “Synthesis of Band-Limited Orthogonal Signals for Multichannel Data Transmission,” Bell System Technical Journal, 45, pp. 1775-1796. 9 B. R. Salzberg [1967], “Performance of an Efficient Parallel Data Transmission System,” IEEE Transactions on Communication Technology, 15, 6, pp 805-811 9 R.W. Chang, and R.A. Gibby [1968], “Theoretical Study of Performance of an Orthogonal Multiplexing Data Transmission Scheme,” IEEE Transactions on Communication Technology, 16, 4, pp. 529-540. 9 S.B. Weinstein, and P.M. Ebert [1971], “Data Transmission by Frequency-Division Multiplexing Using the Discrete Fourier Transform,” IEEE Transactions on Communication Technology, 19, 5, pp. 628-634

15 OFDMA Operations

NE Subcarriers Pilot

Subchannel A Subchannel B Group 1 Group 2 Group NG 1 FFT Preamble Ranging Sub Channels SS A SS B SS C Sub Channels

SS D SS E Time

‰ Different modulation/coding in each sub channel ‰ Media Access Protocol (MAP) messages are used to assign SSs to Sub channels ≈ nd ‰ FFT Size = 2048; DL: NG = 48 / NE = 32; UL: NG = 53 / NE = 32; 1 Schannel 1/32 of total BW ‰ Sub-carriers are assigned in a pseudorandom fashion to the SSs ‰ High throughput SSs are assigned more that one SC ‰ SSs need only modulate a few of the 2048 SCs/ BS modulates all Î Commensurate with low power CPEs and building penetration loss ‰ Throughput per Sub channel (6 MHz) = 178.1 (QPSK) / 428.1 (16QAM) / 668.7 (64 QAM) (kbps) ‰ Total Throughput (6 MHz) = 4.8 / 11.6 / 18.2 MBPS

Reference: Koffman, Roman, “Broadband Wireless Access Solutions Based on OFDM Access in IEEE 802.16”, IEEE Comm. Magazine,April 2002, pp 94-103 16 Spectrum Availability

License Exempt Upper Licensed Low/Mid UNII UHF ISM UPCS WCS ISM MMDS Int’l Int’l UNII & ISM

1 2 3 4 5 GHz

UHF 0.75 - 0.8 Channels 60-69, called the upper 700Mhz, are by congressional statute to be reclaimed for new services (broadband wireless). ISM 0.9 - 0.93 Industrial, Scientific & Medical Band – License exempt band UPCS 1.91 - 1.93 License exempt Personal Communications Services WCS 2.3 Wireless Communications Service. Licensed by Verizon, Bellsouth & AT&T

ISM 2.4 - 2.48 Industrial, Scientific & Medical Band – License exempt band

MMDS 2.5 - 2.7 Multi-channel Multipoint Distribution Service. Licensed in U.S. by Sprint, Worldcom & Nextel, Nucentrix.

Int’l 3.4 - 3.7 Licensed Bands- Europe, Latin America, Asia 4.8 - 5 Licensed Bands-Japan

UNII 5.15 - 5.35 License exempt National Information Infrastructure band 5.73 - 7.83 US Gov’t Exclusive Source: Intel Corporation Non-Gov’t Exclusive 17 802.16 Vendors

Rosedale System on a Chip: 802.16-2004 MAC + OFDM PHY + integrated 10/100 MAC+ Inline security processing + TDM controller interface “April 18, 2005 - Intel Corporation today announced the availability of its first WiMAX product”

Carrier Band-Width OTA Vendor Product Frequency Modulation Features Inteface (MHz) Throughput (GHz) E1 + IP PrimeMax 3.5, 5.8 7/ 10/14/20 OFDM 256 <50 MBPS 100bT/E1/T1 (Backhaul) OFDM256/ Optimized for AAS/MIMO/ HiperMax 3.5/2.5 1.75/3/5/7/10 10/100bT SOFDMA 802.16e full QoS 3.5, 2.3, 2.5- 10/100bT, BreezeMax 1.75/3.5 OFDM 256 10 MBPS Full QoS 2.7 RJ11 (CPE) Packetwave 2.5, 3.5, 5.3, 2-6 MHz SC TDMA 20 Full QoS 100bT 1000 5.8

Horizon 5.8 10 OFDM 256 50 <16 sector/ 1000bT

3.4-3.8/ 5.4- 50 @ 10 MHz Full QoS/ RedMAX 3.5,5, 7, 10 OFDM 256 T1/100bT 5.8 chan BCMC

+ = E1/WiMAX April 20, 2005 CESoP technology WiMAX chip

18 WiMax Equipment

1/2 λ typical 10 λ = ~ 5 ft. Outdoor 3 Sided Structure

~ 1’ 48” 10 λ Dual Element, = ~ 5 ft. Vertically Polarized Panel Antenna Indoor 10 λ typical Jumper One antenna cable shown Mast cable 4 Sided Structure 100 ft. typical RJ11, E1/T1, Ethernet Interfaces Feeder cable 10-25 ft.

Service Provider Network 600 mm / 24” width Gateway GW PSTN 450 mm / 18” depth 2135 mm / 84” height Backhaul Router PC Card ISP Embedded Network RADIUS Client SS Side BS Side 19 System Operation

SS “enters” SS BS BS service area SS Scans for DL Channel DL-MAP Broadcast: Phy Synch field, Operator ID, Sector ID, MAP message length, Î DL Synched Obtain UL Parameters DCD broadcast: BS Power, PHY type, DL burst profile, Modulation type, FEC, Phy synch, BSID + UCD broadcast: PHYsycnhfield,BSID,Physpecs,

Ranging and Adjust Range-Req: requested DL burst profile, SS MAC addr, Ranging anomalies, SS broadcast Parameters capabilities Range-Rsp: Timing adjust, Pwr lvl adjust, Freq offset adj, ranging status, DL freq override, UL freq override, burst profile, SS Mac addr, CID, ... Negotiate Basic SS Bc-Req: CID, PHY params supported, Bandwidth allocations supported, Capabilities SS Bc-Rsp: CID, PHY params supported, Bandwidth allocations supported,

Register with Reg-Req: CID, Hashed Msg Auth Code, IP vers, Vendor ID, CS capability, ARQ params BS Reg-Rsp: CID, Ok/Not, HMAC tuple, IP vers, Vendor ID, CS capability, ARQ params

Establish IP DHCP-Req: H/W type = Ethernet, MAC addr., Params requested: Subnet mask, Time offset, Connectivity Router option, Time server option, Vendor class identifier DHCP-Req: IP Addr., TFTP provisioning server name, Time offset, List of routers, Establish ToD ToD Req/Rsp Transfer Operational TFTP Config File(Download SS binary Configuration File) Parameters TFTP Complete: CID TFTP RSP: CID, OK/Not

Establish Provisioned DSA-Req (SS or BS initiated): Service flow params, CS parameter encodings(802.3, 802.1p, 1q, Connections ATM..), DSA-Rsp): CID, Trnsaction ID, Conirmation Code, Service flow params, CS param encodings, Service flow error set, Operational DSA: Dynamic Service Allocation 20 802.16 QoS Offerings

‰ Almost identical to DOCSIS QoS features ‰ Service flows defined for different QoS traffic in each SS↔BS connection (CID) ‰ Every service is connection based, even connectionless services such as IP

Higher Layers Higher Layers ATM/IP/Ether ATM/IP/Ether Service Specific Service Specific 802.16 BS Convergence 802.16 SS Convergence sub-layer sub-layer MAC MAC SFID 1 PHY PHY SFID 1 SFID 2 CID CID SFID 2 SFID 3 SFID 3

QoS Class Type of traffic Scheduling Parameters Unsloicited grant size, Reatlime data services with fixed size data BS grants service periodically. Unsolicited Grant Grants per interval, Nominal and period transmissions. E.g: T1/E1/VoIP SS contention and piggyback Service (UGS) grant interval, Tolerated w/o silence suppression requests prohibited. grant jitter Periodic unicast request Nominal polling interval, Realtime Polling Real time data with variable sized packets opportunities granted to SS. tolerated poll jitter, minimum Services (rtPS) and with periodic transmission. E.g: MPEG Contention/piggyback requests reserved traffic rate prohibited Periodic unicast request Non-realtime opportunities granted to SS but Nominal polling interval, Delay tolerant with variable packet size and polling services farther apart. minimum reserved traffic aperiodic transmission. E.g.: FTP (nrtPS) Contention/piggyback requests rate, traffic priority allowed Contention/piggyback requests Minimum reserved traffic Best Effort (BE) Handled on a space available basis from SS to BS rate, traffic priority 21 802.16e Additions Mobility Support Features: ‰ Licensed Band Only: 2 to 6 GHz ‰ Handoff: HO, SHO, FBSS (Fast BS Switching) ‰ BS Classifications: Neighbor, Serving, Target, Active MSS MSS ‰ Active Set: List of BSs available to MS, maintained by BS and MS ‰ The BSs arranged in geographically contiguous paging groups U ‰ Network Topology Advertisement: Each BS transmits its own and neighbor’s channel info.

Improved PHY and MSS Features IB ‰ Low Density Parity Check Codes at the Physical Layer BS BS ‰ Enhanced MIMO setup functions ‰ New States for MS operation: Sleep Mode (reduces MS power, and optimizes BS air interface A capacity), Parameter defined Power Saving Classes of Mobiles ‰ Enhanced FFT sizes for Scalable OFDMA: 2048, 1024, 512, 128ÆBandwidth flexibility MAC and QoS Features: ‰ Global Service Flows defined for operation over varying topologies with mobility ASA Servers ‰ 4 New MAP headers defined to help in PHY Channel reporting, feedback, combined Authentication bandwidth-power requests ... and service authorization ‰ QoS - ErtPS: The ErtPS adds to rtPS Æ support real-time service flows that generate variable (ASA) size data packets on a periodic basis, e.g.VoIP with silence suppression. Service Features: ‰ Enhanced Multicast Broadcast Service

22 WiBro: 2.3 GHz Portable Internet Standardization and Commercialization: ‰ Korean standardization effort Æ TTA ‰ Named in April 2004: Wireless Broadband Æ WiBro ‰ Urban, High data rate >1 MBPS @ <60 km/hr ‰ Draft Completion/802.16e Harmonization: Q205, Field testing : 4Q05, Commercialization: 1Q06 ‰ Korea Information Strategy Development Institute: “>10.5M users by 2010” Source: ITU-APT Regional Seminar 2004 System Profile ‰ Standard activities: Radio (PHY, MAC, RRC), Services & Network, IPR Processing, I’natl coordination PSS PSS ‰ System Definition: ƒ Frequency Reuse: 1 ƒ 2.3 GHz only ƒ TDD-only with 5 m-sec framing ƒ Service Coverage: 1 km ƒ Mobility < 60 km/hr, ƒ Spectral Efficiency: DL/UL = 6/2 (max) 2/1 (avg) RAS RAS ƒ Throughput/user: DL/UL = 3/1 Mbps (max); 512/128 kbps (avg) ƒ Throughput/sector: DL/UL = 18/6 MBPS ƒ QPSK/16/64 QAM ƒ Handoff time: 150 ms ACR ƒ 10 MHz B/W OFDMA

‰ Network elements: PSS (Personal SS), RAS (Radio Access Station), ACR (Access Control Core Router) ‰ ACR: Packet classification, header suppression, service flow management, traffic switching and integration, H/O management... 23 Summary

‰ New services upcoming with Bluetooth and Zigbee ‰ WiFi devices almost everywhere: Embedded devices ‰ WiFi citywide coverage on the rise: Taipei deploying, Tempe/Phila/SF (planning) ‰ WiMAX offers high coverage, throughput for Fixed/Nomadic/Mobile services ‰ WiMAX guarantees QoS ‰ WiMAX operates in NLOS environments increasing the serviceable area ‰ WiBro becoming a service in 1Q06 in Seoul ‰ 802.16e is well suited for urban, high throughput at <60 km/hr

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