Our G-enealogy Brough Turner Founder & CTO Ashtonbrooke.com broughturner@gmail.com http://blogs.broughturner.com Our G-enealogy How the history of cellular technology helps us understand 4G technology and business models and their likely impact on wireless broadband • Brief history of cellular wireless telephony – Radio technology: TDMA, CDMA, OFDMA – Mobile core network architectures • Demographics & market trends today – 3.5G, WiMAX, LTE & 4G migration paths • Implications for the next 2-5 years 2 Google “3G Tutorial” “4G Tutorial” Outrageous ideas • 5 GHz spectrum better than 700 MHz • 2020: LTE* >80%; WiMAX* <15% – * i.e. LTE family of networks vs WiMAX evolution • Should ask: Wi-Fi vs LTE + WiMAX – e.g. user owned versus service provider owned • Value of TV white spaces: Secondary access • Open 3 GHz – 10 GHz to all – License exempt on secondary access basis 3 Mobiles overtake fixed Source: ITU World ICT Indicators, June 2008 4 Mobile Generations G Data Rates 1 Analog Typical 2.4 Kbps; max 22 Kbps 2 Digital – TDMA, CDMA 9.6 - 14.4 Kbps (circuit data) 2.5 GPRS – mux packets in voice timeslots 15 - 40 Kbps Improved modulation, using CDMA variants 50 – 144 Kbps (1xRTT); 200 – 384 Kbps (UMTS); 500 Kbps – 2.4 Mbps (EVDO) More modulation tweaks 2–14 Mbps (HSPA), then 28 Mbps & 42/84 Mbps future evolution New modulation (OFDMA); Multi-path (MIMO); All IP LTE: potentially >100 Mbps with adequate spectrum (20 MHz) 3 3.5 4 5 Summary Enormous technology change but commercial issues trump technology and legal-regulatory trumps all 6 Origins of Wireless Communications • 1864: James Clark Maxwell – Predicts existence of radio waves • 1886: Heinrich Rudolph Hertz – Demonstrates radio waves • 1895-1901: Guglielmo Marconi – Demonstrates wireless communications over increasing distances • Also in the 1890s – Nikola Tesla, Alexander Stepanovich Popov, Jagdish Chandra Bose and others, demonstrate forms of wireless communications 8 First Mobile Radio Telephone, 1924 Courtesy of Rich Howard 9 Cellular Mobile Telephony Antenna diversity Cellular concept 2 ● Bell Labs (1957 & 1960) Frequency reuse ● typically every 7 cells Handoff as caller moves Modified CO switch ● HLR, paging, handoffs Sectors improve reuse ● every 3 cells possible 10 5 3 1 2 1 7 2 5 1 6 4 7 5 3 2 2 3 6 4 7 3 6 1 4 7 5 First Generation (nearly all retired) • Advanced Mobile Phone Service (AMPS) – US trials 1978; deployed in Japan (’79) & US (’83) – 800 MHz; two 20 MHz bands; TIA-553 • Nordic Mobile Telephony (NMT) – Sweden, Norway, Demark & Finland – Launched 1981 – 450 MHz; later at 900 MHz (NMT900) • Total Access Communications System (TACS) – British design; similar to AMPS; deployed 1985 11 2nd Generation – digital systems • Leverage technology to increase capacity – Speech compression; digital signal processing • Utilize/extend “Intelligent Network” concepts – Improve fraud prevention; Add new services • Wide diversity of 2G systems – – – – 12 IS-54/ IS-136 Digital AMPS; PDC (Japan) DECT and PHS; iDEN IS-95 CDMA (cdmaOne) GSM 2G “CDMA” (cdmaOne) • Code Division Multiple Access – all users share same frequency band – discussed in detail later as CDMA is basis for 3G • Qualcomm demo in 1989 – claimed improved capacity & simplified planning • First deployment in Hong Kong late 1994 • Major success in Korea (1M subs by 1996) • Adopted by Verizon and Sprint in US • Easy migration to 3G (same modulation) 13 GSM – Global System for Mobile • Originally “Groupe Spécial Mobile ” – joint European effort beginning 1982 – Focus: seamless roaming all Europe • Services launched 1991 – time division multiple access (8 users per 200KHz) – 900 MHz band; later 1800 MHz; then 850/1900 MHz • GSM – dominant world standard today – well defined interfaces; many competitors; lowest cost to deploy – network effect took hold in late 1990s 14 GSM Dominant Today • GSM+3GSM used by 88% of subscribers worldwide • Asia leads with 42% of all mobile subscriptions – AT&T and T-Mobile use GSM/3GSM in US today GSM Subscribers Source: Wireless Intelligence / GSM Association 15 GSM substantially enhanced Widely deployed significant payback for enhancements • HSCSD - high speed circuit-switched data • GPRS - general packet radio service • Synchronization between cells – Minimize interference; help fix mobile’s location • AMR vocoder – increase capacity (& fidelity) • Frequency hopping (to overcome fading) • Discontinuous transmission (more calls/ cell) • Cell overlays with reuse partioning 16 1G, 2G, 3G Multi-Access Technologies Courtesy of Petri Possi, UMTS World 4G and future wireless systems optimize a combination of frequency, time and coding e.g. OFDMA & SC-FDMA (discussed later) 17 2G & 3G – Code Division Multiple Access • Spread spectrum modulation – originally developed for the military – resists jamming and many kinds of interference – coded modulation hidden from those w/o the code • All users share same (large) block of spectrum – one for one frequency reuse – soft handoffs possible • All 3G radio standards based on CDMA – CDMA2000, W-CDMA and TD-SCDMA 18 Courtesy of Suresh Goyal & Rich Howard 19 The 3G Vision • Universal global roaming – Sought 1 standard (not 7), (but got 3: 3GSM, CDMA 2000 & TD-SCDMA) • Increased data rates • Multimedia (voice, data & video) • Increased capacity (more spectrally efficient) • Data-centric architecture (ATM at first, later IP) • But deployment took much longer than expected – No killer data app; new spectrum costly; telecom bubble burst; much of the vision was vendor-driven 20 3G Radio technology today • CDMA 2000 – Multi Carrier CDMA – Evolution of IS-95 CDMA; but now a dead end • UMTS (W-CDMA, HSPA) – Direct Spread CDMA – Defined by 3GPP Paired spectrum bands • TD-SCDMA – Time Division Synchronous CDMA – Defined by Chinese Academy of Telecommunications Technology under the Ministry of Information Industry Single spectral band with time division duplexing 21 Why CDMA 2000 lost out • Had better migration story from 2G to 3G – Evolution from original Qualcomm CDMA (IS-95) – cdmaOne operators didn’t need additional spectrum • Higher data rates than UMTS, at least at first • Couldn’t compete with GSM’s critical mass – Last straw when Verizon Wireless selected 3GPP’s Long Term Evolution (LTE) for their 4G network – Verizon selection 11/07 – Qualcomm abandons further development 11/08 22 3GPP (3rd Generation Partnership Project) Japan USA • Partnership of 6 regional standards groups, which translate 3GPP specifications to regional standards • Controls evolution of GSM, 3GSM (UMTS, WCDMA, HSPA) & LTE 23 23 UMTS (3GSM) is market leader • GSM evolution: W-CDMA, HSDPA, HSPA, +… – leverages GSM’s dominant position • Legally mandated in Europe and elsewhere • Requires substantial new spectrum – 5 MHz each way (symmetric) at a minimum • Slow start (was behind CDMA 2000), but now the accepted leader – Network effect built on GSM’s >80% market share – Surely LTE will benefit in the same fashion… 24 TD-SCDMA (Time division synchronous CDMA) • Chinese development – IPR bargaining tool with West? Late to market, but big deployment plans • Single spectral band – unpaired spectrum; as little as 1.6 MHz; time division duplex (TDD) with high spectral efficiency; good match for asymmetrical traffic! • Power amplifiers must be very linear – relatively hard to meet specifications 25 China 3G • Largest mobile market in world (630 M subs) – Largest population in world (1.3 billion) • Home-brew 3G standard: TD-SCDMA – 3G licenses were delayed until TD-SCDMA worked – 2008 trials: 10 cities, 15K BSs & 60K handsets • 3G granted January 2009 – China Mobile: TD-SCDMA – China Unicom: 3GSM (UMTS) – China Telecom: CDMA 2000 26 3G Adoption – DoCoMo Japan 2G: mova 3G: FOMA Potential to discontinue 2G services in 2010 … 27 3G Subscribers (2Q 2008) • 18% on 3G; 82% on 2G; 0.01% on 1G • EU & US 3G penetration approaching 30% • US penetration rate soaring 3-month averages ending June 2008 & June 2007 All mobile subscribers ages 13+ Source: comScore MobiLens 28 3G data-only subscribers • Soaring adoption of 3G “USB Data Modems” – 92% of all 3G data bytes in Finland in 2H07 • Informa on EU 3G devices, May 2008 – 101.5M 3G devices: 64 M handsets, 37M 3G data modems • In-Stat/ ABI Research – In-Stat: 5M cellular modems in 2006 – ABI Research 300% growth in 2007, i.e. 20M? Enormous growth, from a relatively small base… 29 Diverse Mobile Wireless Spectrum 30 Wireless Migration 31 OFDM →OFDMA MIMO Wireless capacity / throughput 4G LTE 3G 2G UMTS/HSPA CDMA First cell phones GSM AMPS 1970 32 WiMAX Wi-Fi 1980 1990 2000 2010 ITU-T Framework Pervasive connectivity WLAN - WMAN - WWAN ITU-T – United Nations telecommunications standards organization Accepts detailed standards contributions from 3GPP, IEEE and other groups 33 3GPP – WWAN (wireless wide area network) IEEE 802.16 – WMAN (wireless metropolitan area network) IEEE 802.11 – WLAN (wireless local area network) ITU Mobile Telecommunications • IMT-2000 – Global standard for third generation (3G) wireless – Detailed specifications from 3GPP, 3GPP2, ETSI and others • IMT-Advanced – New communications framework: deployment ~2010 to 2015 – Data rates to reach around 100 Mbps for high mobility and 1 Gbps for nomadic networks (i.e. WLANs) – High mobility case via either or both evolved LTE & WiMAX – 802.11ac and 802.11ad addressing the nomadic case 34 LTE highlights • Sophisticated multiple access schemes – DL: OFDMA with Cyclic Prefix (CP) – UL: Single Carrier FDMA (SC-FDMA) with CP • Adaptive modulation and coding – QPSK, 16QAM, and 64QAM – 1/3 coding rate, two 8-state constituent encoders, and a contention-free internal interleaver • Advanced MIMO spatial multiplexing – (2 or 4) x (2 or 4) downlink and uplink 35 4G Technology – OFDMA • Orthogonal Frequency Division Multiple Access – Supercedes CDMA used in all 3G variants • OFDMA = Orthogonal Frequency Division Multiplexing (OFDM) plus statistical multiplexing – Optimization of time, frequency & code multiplexing • OFDM already deployed in 802.11a & 802.11g – Took Wi-Fi from 11 Mbps to 54 Mbps & beyond 36 Orthogonal Frequency Division Multiplexing – Many closely-spaced sub-carriers, chosen to be orthogonal, thus eliminating inter-carrier interference – Varies bits per sub-carrier based on instantaneous received power 37 Statistical Multiplexing (in OFDMA) • Dynamically allocate user data to sub-carriers based on instantaneous data rates and varying sub-carrier capacities • Highly efficient use of spectrum • Robust against fading, e.g. for mobile operation 38 FDMA vs. OFDMA • OFDMA more frequency efficient • Dynamically map traffic to frequencies based on their instantaneous throughput Guard band Channel FDMA 39 OFDMA 4G Technology - MIMO 40 Multiple Input Multiple Output smart antenna technology Multiple paths improve link reliability and increase spectral efficiency (bps per Hz), range and directionality Municipal Multipath Environment 41 SDMA = Smart Antenna Technologies • Beamforming – Use multiple-antennas to spatially shape the beam • Spatial Multiplexing a.k.a. Collaborative MIMO – Multiple streams transmitted – Multi-antenna receivers separate the streams to achieve higher throughput – On uplink, multiple singleantenna stations can transmit simultaneously • Space-Time Codes – Transmit diversity such as Alamouti code reduces fading 42 2x2 Collaborative MIMO give 2x peak data rate by transmitting two data streams 4G Technology – SC-FDMA • Single carrier multiple access – Used for LTE uplinks – Being considered for 802.16m uplink • Similar structure and performance to OFDMA – Single carrier modulation with DFT-spread orthogonal frequency multiplexing and FD equalization • Lower Peak to Average Power Ratio (PAPR) – Improves cell-edge performance – Transmit efficiency conserves handset battery life 43 Key Features of WiMAX and LTE • • • • OFDMA (Orthogonal Frequency Division Multiple Access) Users are allocated a slice in time and frequency Flexible, dynamic per user resource allocation Base station scheduler for uplink and downlink resource allocation – Resource allocation information conveyed on a frame‐by frame basis • Support for TDD (time division duplex) and FDD (frequency division duplex) TDD: single frequency channel for uplink and downlink DL UL DL UL 44 FDD Paired channels 3G/4G Comparison Peak Data Rate (Mbps) 45 Access time (msec) Downlink Uplink HSPA (today) 14 Mbps 2 Mbps 50-250 msec HSPA (Release 7) MIMO 2x2 28 Mbps 11.6 Mbps 50-250 msec HSPA + (MIMO, 64QAM Downlink) 42 Mbps 11.6 Mbps 50-250 msec WiMAX Release 1.0 TDD (2:1 UL/DL ratio), 10 MHz channel 40 Mbps 10 Mbps 40 msec LTE (Release 8), 5+5 MHz channel 43.2 Mbps 21.6 Mbps 30 msec WiMAX vs. LTE • Commonalities – IP-based – OFDMA and MIMO – Similar data rates and channel widths • Differences – Carriers are able to set requirements for LTE through organizations like NGMN and LSTI, but cannot do this as easily at the IEEE-based 802.16 – LTE backhaul is, at least partially, designed to support legacy services while WiMAX assumes greenfield deployments 46 Commercial Issues LTE • Deployments likely slower than projected • 2-3 year lead, likely maintained for years But • Dedicated spectrum in many countries • Eventual migration path for GSM/3GSM, i.e. for > 80% share • Will be lowest cost & dominant in 2020 47 WiMAX But • Likely < 15% share by 2020 & thus more costly 3G Partnership Project Defines migration GSM to UMTS/ 3GSM to LTE Release Specs complete First deployed Major new features defined 98 1998 99 1Q 2000 2003 W-CDMA air interface 4 2Q 2001 2004 Softswitching IP in core network 5 1Q 2002 2006 HSDPA & IP Multimedia System (IMS) 6 4Q 2004 2007 HSUPA, MBMS, GAN, PoC & WLAN integration 7 4Q 2007 future HSPA+, Better latency & QoS for VoIP 8 4Q 2008 * future LTE, All-IP Last purely 2G GSM release W-CDMA – Wideband CDMA modulation * Rush job? HSxPA – High Speed (Download/Upload) Packet Access MBMS – Multimedia Broadcast Multicast Service GAN – Generic Access Network PoC – Push-to-talk over Cellular LTE – Long Term Evolution, a new air interface based on OFDM modulation 48 Core Network Architectures • Two widely deployed architectures today • 3GPP evolved from GSM-MAP – Used by GSM & 3GSM operators (88% of subs globally) – “Mobile Application Part” defines signaling for mobility, authentication, etc. • 3GPP2 evolved from ANSI-41 MAP – ANSI-41 used with AMPS, TDMA & CDMA 2000 – GAIT (GSM ANSI Interoperability Team) allowed interoperation, i.e., roaming • Evolving to common “all IP” vision based on 3GPP 49 Typical 2G Mobile Architecture PSDN BSC BTS BSC HLR SMS-SC PLMN MSC/VLR BSC MSC/VLR BSC BTS Base Transceiver Station BSC Base Station Controller GMSC Tandem CO Tandem CO CO 50 PSTN MSC Mobile Switching Center VLR Visitor Location Register HLR Home Location Register Separation of Signaling & Transport • Like PSTN, 2G mobile networks have one network plane for voice circuits and another network plane for signaling • Some elements reside only in the signaling plane – HLR, VLR, SMS Center, … HLR MSC MSC SMS-SC VLR MSC Signaling Plane (SS7) Transport Plane (Voice) 51 Signaling in Core Network • Based on SS7 – ISUP and specific Application Parts • GSM MAP and ANSI-41 services – mobility, call-handling, O&M, authentication, supplementary services, SMS, … • Location registers for mobility management – HLR: home location register has permanent data – VLR: visitor location register – local copy for roamers 52 PSTN-to-Mobile Call PLMN PLMN (Visitor) (Home) PSTN (SCP) HLR Signaling over SS7 SCP Where is the subscriber? MAP/ IS41 (over TCAP) (STP) ISUP 4 Provide Roaming 2 3 5 Routing Info VMSC MS BSS (SSP) 6 IAM 1 GMSC IAM (STP) (SSP) VLR 514 581 ... 53 (SSP) GSM 2G Architecture NSS BSS E Abis PSTN A PSTN B BSC MS BTS C MSC VLR D GMSC SS7 H HLR BSS Base Station System NSS Network Sub-System BTS Base Transceiver Station MSC Mobile-service Switching Controller BSC Base Station Controller VLR Visitor Location Register MS Mobile Station HLR Home Location Register AuC Authentication Server GMSC Gateway MSC 54 AuC GSM Global System for Mobile communication 2.5G Architectural Detail 2G MS (voice only) NSS BSS E Abis PSTN A PSTN B BSC MS C MSC BTS Gs GMSC D VLR SS7 H Gb 2G+ MS (voice&data) Gr HLR AuC Gc Gn SGSN IP PSDN GGSN BSS Base Station System NSS Network Sub-System SGSN Serving GPRS Support Node BTS Base Transceiver Station MSC Mobile-service Switching Controller GGSN Gateway GPRS Support Node BSC Base Station Controller VLR Visitor Location Register HLR Home Location Register AuC Authentication Server 55 Gi GMSC Gateway MSC GPRS General Packet Radio Service 3G rel99 Architecture (UMTS) 2G MS (voice only) CN BSS E Abis PSTN A PSTN B BSC Gb BTS C MSC Gs GMSC D VLR SS7 H 2G+ MS (voice & data) IuCS RNS Gr HLR ATM Iub IuPS RNC AuC Gc Gn SGSN Gi IP PSDN GGSN Node B 3G UE (voice & data) BSS Base Station System CN Core Network SGSN Serving GPRS Support Node BTS Base Transceiver Station MSC Mobile-service Switching Controller GGSN Gateway GPRS Support Node BSC Base Station Controller VLR Visitor Location Register HLR Home Location Register RNS Radio Network System RNC Radio Network Controller 56 AuC Authentication Server GMSC Gateway MSC UMTS Universal Mobile Telecommunication System 3G rel4 - Soft Switching 2G MS (voice only) CN CS-MGW A Abis Nc Mc BSC Gb BTS CS-MGW Nb BSS PSTN B C MSC Server Gs PSTN Mc GMSC server D VLR SS7 H 2G+ MS (voice & data) IuCS RNS Gr HLR ATM Iub IuPS RNC AuC IP/ATM Gc Gn SGSN Gi PSDN GGSN Node B 3G UE (voice & data) BSS Base Station System CN Core Network SGSN Serving GPRS Support Node BTS Base Transceiver Station MSC Mobile-service Switching Controller GGSN Gateway GPRS Support Node BSC Base Station Controller VLR Visitor Location Register HLR Home Location Register 57 RNS Radio Network System AuC Authentication Server RNC Radio Network Controller GMSC Gateway MSC 3GPP rel5 ― IP Multimedia 2G MS (voice only) CN CS-MGW A/IuCS Abis Nc Mc BSC Gb/IuPS BTS 2G+ MS (voice & data) IuCS C VLR GMSC server D SS7 H ATM Gr IuPS HSS AuC IP/ATM Gc Gn Gi SGSN GGSN Node B 3G UE (voice & data) IM-MGW IM Gs IM IP Multimedia sub-system PSTN MRF Media Resource Function IP CSCF Call State Control Function Mg MGCF Media Gateway Control Function (Mc=H248,Mg=SIP) MRF Mc MGCF IM-MGW IP Multimedia-MGW CSCF 58 PSTN B RNS RNC PSTN Mc MSC Server Gs Iub CS-MGW Nb BSS IP Network 3GPP2 Defines IS-41 Evolution • 3rd Generation Partnership Project “Two” – Evolution of IS-41 to “all IP” more direct (skips ATM stage), but not any faster – Goal of ultimate merger (3GPP + 3GPP2) remains • • • • • 59 1xRTT – IP packets (like GPRS) 1xEVDO – Evolution data-optimized 1xEVDV – abandoned 3x – Triples radio data rates Universal Mobile Broadband (UMB) – abandoned NextGen Networks (NGN) Converging 3GPP IMS R7 Packet Cable 2.0 ATIS NGN FG ITU-T NGN FG TISPAN R1 Following 3GPP lead 3GPP2 MMD 3GPP IMS R6 3GPP IMS R5 3GPP Release 4 2000 60 2001 2002 2003 2004 2005 2006 3GPP2 — CDMA2000 multi-media domain (MMD) based on 3GPP IMS R5 TISPAN — evolves NGN architecture for fixed networks based on 3GPP IMS ITU-T NGN Focus Group — venue to make TISPAN NGN a global spec ATIS NGN Focus Group — formally collaborating with ETSI as of April 2005 PacketCable Release 2.0 — aligning with portions of 3GPP 3GPP R7 / TISPAN IMS 3GPP Service Layer OSA-SCS App Server IM-SSF Online CCCF Charging Function SLF Offline HSS Service Plane SCIM S-CSCF I-CSCF P-CSCF 3GPP Control Layer IBCF BGCF MRFC MGCF Control Plane PDF NASS ETSI TISPAN Extension Access/Transport Plane Other Networks 61 A-BGF RACS MRFP Internal IP Networks T-MGF SGF PSTN I-BGF IWF External IP Networks IMS / NGN Vision • One core network for “any access” – Based on IP, using IETF standards, with extensions – Wireline and wireless transparency • Access and bandwidth will be commodities; services are the differentiator – Per-session control supports per-application quality of service (QoS) and per-application billing • Voice is just application – “Easily” integrated with other applications… 62 IMS Story: Convergence IMS Services Phone Tools TV Caller ID TV Caller ID Push to Talk Application Application Subscriber Data Subscriber Data Media Functions Access Delivery Access Delivery Media Functions Push to Talk Application Application Subscriber Data OSS/ BSS Media Functions Application OSS/ BSS Subscriber Data OSS/ BSS Application Phone Tools OSS/ BSS Traditional Services Media Functions Access Delivery IP Multimedia Subsystem Wireline Packet Cable Wireless Wifi WiMax Wireline Packet Cable Wireless Wifi WiMax Source: Team Analysis, Lucent 63 IMS / NGN Value Proposition • Generate new revenue from new services – Per-session control allows IMS to guarantee QoS for each IP session, and enables differential billing for applications & content • Reduce capital spending – Converge all services on common infrastructure – Focus limited resources on core competencies • To date, mobile operators have had no incentive to deploy IMS for voice services 64 LTE and IMS • LTE is an all-IP network – Not compatible with legacy voice services – Assumes the use of IP Multimedia System (IMS) • Initial LTE networks will be data only • Initial LTE handsets will be multi-modal, supporting HSPA and earlier systems for voice telephony • VOLGA Forum working on a fix – Voice over LTE via Generic Access 65 Long Term Parallels: IN & IMS Intelligent Network • Free operators from equipment provider lock-in • Separate applications from basic call control • Open protocols and APIs for applications Intelligent Network Application Successes • FreePhone, Mobile (HLR), Pre-paid, Voice mail, … • 15 year summary: A few applications, very widely deployed 66 LTE’s System Architecture Evolution (SAE) RAN (Radio access network) SGSN (Serving GPRS Support Node) PCRF (policy and charging function) HSS (Home Subscriber Server) MME (Mobility Management Entity) SAE (System Architecture Evolution) 67 Diagram by Huawei Mobile Service Revenues • > $800 billion in 2007, growing 6%-7% per year – > $1 trillion by 2012 • Voice services dominate: 81% • SMS services: 9.5% ; All other non-voice services: 9.5% Source: Portio Research 68 Images courtesy of Jon Stern 69 Mobile Services Futures • Affordable open mobile Internet access coming – Five competing 3.5G operators in US by 2010 – Smart phone penetration soaring • Operators’ control of handset software slipping – iPhone and Android application stores, initiatives for Symbian, WinMobile, Adobe AIR, etc. 70 The Internet is the killer platform • Mobile Internet access driving 3G data usage • Future business models an open question • Slides from yesterday’s Mobile Broadband discussion, are available 71 Enormous technology change but commercial issues trump technology and legal-regulatory trumps all 72 Outrageous ideas • 5 GHz spectrum better than 700 MHz • 2020: LTE* >80%; WiMAX* <15% – * i.e. LTE family of networks vs WiMAX evolution • Should ask: Wi-Fi vs LTE + WiMAX • Value of TV white spaces: Secondary access • Open 3 GHz – 10 GHz to all – License exempt on secondary access basis 73 Thank you ! Brough Turner broughturner@gmail.com http://blogs.broughturner.com