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Broadband Access Networks 광대역가입자망

Broadband Access Networks 광대역가입자망. 권순철 scgweon(@kt.co.kr) (Tel. 042-866-3890) Korea Telecom ANRL. CONTENTS. Introduction Characteristics of Subscriber Loop ISDN xDSL LMDS HFC/Cable modem FITL PON FTTC Powering FSAN activities Conclusion. INTRODUCTION. 환경의 변화 국내시장 환경 가입자망 기술동향.

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Broadband Access Networks 광대역가입자망

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  1. Broadband Access Networks광대역가입자망 권순철 scgweon(@kt.co.kr) (Tel. 042-866-3890) Korea Telecom ANRL

  2. CONTENTS • Introduction • Characteristics of Subscriber Loop • ISDN • xDSL • LMDS • HFC/Cable modem • FITL • PON • FTTC Powering • FSAN activities • Conclusion

  3. INTRODUCTION • 환경의 변화 • 국내시장 환경 • 가입자망 기술동향

  4. 환경의 변화 • 사용자의 변화 • 서비스의 변화 • 네트워크의 변화 • 시장환경의 변화

  5. 사용자의 변화 • PC 사용자의 증가로 멀티미디어 서비스(bandwidth consuming)에 친숙해 지기 시작함 • 비즈니스가 인터넷의 진화를 주도하면서 소비자와 WWW가 인터넷의 신화를 창조함 • 인터넷의 확산으로 홈페이지, 전자우편이 활성화되기 시작됨 • Cyber & Plug-in Generation의 등장 • SOHO/창업의 급성장 “The internet and the personal computer are more important than the invention of the telephone and television” - Bill Gates

  6. 서비스의 변화 • Demand for high quality voice service, fast data service and multimedia services • “What to get” is more important than “How to access” • The Internet will be a global institution of communications and commerce • Information technology will be rapidly advanced • Most services not clearly defined yet • Special interest groups and the corporate market first • security, VPN (*MPLS), e-commerce

  7. 네트워크의 변화 • 음성위주의 네트워크는 정체 상태임 • 20년 후면 Data Traffic이 90% 이상 점유 예상 • 미국의 경우 2002년 인터넷/데이터 시장이 기존의 음성시장과 같아질 것으로 예상 • Circuit Switching에서 Packet Switching으로 전환 • 데이터 전용 네트워크의 등장이 가시화 “Data bits exceed voice bits on the PSTN today, if you include fax as data” - John Roth, Nortel

  8. New market demand prompts new supply • Qwest -- 20,000 mile OC-192 net, with 8-way WDM in rings. With 48 fibers, that’s 2 terabits/sec. Plus an empty conduit... • IXC -- 20,000 mile OC-192 net, 20 fibers. • Frontier -- 15,000 miles; fONOROLA -- 15,000 miles in Canada; Level 3 -- 15,000 miles with multiple fibers and conduits. • Project OXYGEN -- 168,000 km undersea fiber network, with a minimum of 1,280 Gbps capacity to 99 cable landing points in 78 countries. On terrestrial routes it will go up to 2 terabits/sec. *한국은 2001년 2/4 (인천) www.qwest.net www.ixc-comm.com

  9. - Differentiated - Cell relay - Best-effort IP IP Services - Frame relay Service - IP VPN, VoIP - Voice, Video IP over SDH/WDM IP over ATM Telco Services Network IP ATM Services SDH WDM Optical Fiber The Club sandwich debates go on

  10. Technical Terminology • How many of you know all of terminology? • Broadband, Attenuation, Bridged Tap, Crosstalk, RFI, POTS, FSN, DSL, ISDN, HDSL, ADSL, RADSL, CDSL, UADSL, SDSL, MSDSL, VDSL, DSLAM, WildWire, FireWire • HFC, FTTO, FTTC, FTTH, MMDS, LMDS, WLL, PCS, IMT-2000, DMT, CAP, QPSK, CATV, VOD, FLC, HDT, ONU, FITL, ADS, PON, TDMA, CDMA, WDMA, SCMA, ATM, SDH, DWDM, UDWDM, Q.2931, DSM-CC, CORBA, TMN, EMS, NMS, SMS • BORSCHT, Local Powering, Centralized Powering • Today’s best is not always future’s best. But today’s best can be most probably future’s best.

  11. 시장환경의 변화 • Increased competitive environment: more competition for operators, more options for users • Rapid increase in number of subscribers • Convergence of different networks (유/무선, 통신/방송, 음성/데이타) • Each carriers(wire/wireless) have to compete every segment of the market • The Rich get richer... • Global service market: SBC/Ameritech/Pacific Telesis, Bell Atlantic/NYNEX/, GTE, AT&T/TCI, BT/MCI • Equipment market: Nortel/Bay, Alcatel/DSC/Coherent, Tellabs/Ciena, Lucent/Yurie, Nortel/Aptis • 전 세계 장비 마켓시장의 90%를 5개사가 독점(?)

  12. 인터넷 시장의 급부상 • Basic technology • Moore’s Law(gates/chip): 18 months; 59%/yr • Optical fiber(bps/fiber): 12 months; 100%/yr • Packet switching (bps/$): 12 months; 100%/yr • Basic demand • Internet users: 12 months; 100%/yr • Data bits: 7.5 months; 300%/yr • Internet core: 4 months; 1,000%/yr

  13. 시내 경쟁 사업자간 비교

  14. KT Network statistics

  15. 국내 서비스별 가입자 현황 * PC통신 가입자수는 제외

  16. 이동전화 사업자별 현황 * SKT 아날로그 가입자 : 259,922명 (3월 대비 72,895명 감소)

  17. 가입자망 기술동향 • 동선 기반 • ISDN • HDSL, SDSL, ADSL, UADSL, VDSL • 동축 케이블 기반 • HFC - 케이블모뎀 • 광섬유 기반 • FTTO, FTTC, FTTH • 무선 기반 • WLL, B-WLL • IMT-2000

  18. ADSL : Asymmetric Digital Subscriber Line • DBS : Direct Broadcast Satellite • FTTC : Fiber To The Curb • HFC : Hybrid Fiber Coaxial • LMDS : Local Multipoint Distribution System • MMDS : Multi-channel Multipoint Distribution System • MSO : Multiple Service Operator Digital 위성방송 (DBS) LMDS만 상향 가능 Fiber or Wireless Hub Station MMDS/LMDS DBS STB/ MMDS/LMDS STB 64Kbps ISDN Adaptor ISDN Line 전 M 화 S 국 O Analog Modem 56Kbps 일반 전화선 6Mbps ADSL Modem Home Terminal 640Kbps Cable Modem Fiber HFC Amp 30Mbps Coax 3Mbps VDSL Modem ONU 52Mbps 3Mbps FTTC/FTTO Fiber Coax or Copper Structure of Access Network

  19. Characteristics of Subscriber Loop • Introduction of loop design • Calculation of Resistance Limit • Calculation of Loss (Attenuation) Limit • Loading Coil • Characteristics of existing TPs • Attenuation • Bridged TAPs • Crosstalk • RFI

  20. D CO Introduction to loop design • Loop Distance D must be limited in length owing to • attenuation of the voice signal • dc resistance for signaling • 6 dB loop attenuation limit (referred to 800 Hz) • 1000  signaling resistance limit • many switches will accept up to 1300  • nominal resistance for the telephone subset in series with the loop is 300  • Korean Environment • 7 dB margin • loop start signaling ~ 1500  (전자식), ~ 2000  (반전자식)

  21. Calculation of Resistance Limit • Loop resistance Rdc (ohm/mi.) • d = diameter of the conductor (in.) • If we want a 10-mi. loop and allow 100 ohm/mi of loop (for the 1000-ohm limit), what diameter of copper wire would we need? 100 = 0.1095/d2 , d = 0.033 in. or 0.84 mm (~20 AWG)

  22. Calculation of Loss (Attenuation) Limit • American Wire Gauge (AWG) vs. wire diameter and resistance • At 20oC • These figures must be doubled for loop/km. (It has a “go” and “return” path)

  23. Calculation of Loss (Attenuation) Limit • Loss per unit length of subscriber cable • Maximum loop length for loop design for the wire gauge • 26 AWG : 6 (dB) / 1.61 = 3.73 km • 24 AWG : 6 / 1.27 = 4.72 km • 22 AWG : 6 / 1.01 = 5.94 km • 19 AWG : 6 / 0.71 = 8.45 km • 16 AWG : 6 / 0.46 = 13.04 km

  24. Loading Coil • Longer Loops without exceeding loss limits • Increasing conductor diameter • Using amplifiers and/or loop extenders • Using inductive loading • Using carrier equipment • Adding load coils • Decreases the velocity of propagation • Increase impedance • Consists of inserting series inductance into the loop at fixed intervals • Code for load coil spacing (ex: 19H88 : 19AWG and 88mH)

  25. Attenuation • Attenuation is a function of signal frequency • introduces intersymbol interferences • Attenuation [in dB] = 10 log10 [Pin (mW) / Pout (mW)] • Example: 4km at 1MHz --> 60dB attenuation • optical fiber attenuation at 1.55 mm = 0.2 dB/km --> 300km for 60dB atten. • Attenuation factor for copper wire • DC - voice band : f 1/2 • ~ 0.5 MHz : f 1/4 • 0.5 MHz ~ : f 1/2

  26. Bridged TAP Effect of bridged tap Attenuation [dB] Echo influencing “equalizer” CO Customer Echo influencing “echo canceller” Frequency Bridged TAPs • Attachment of open circuited twisted pair for a variety of past needs, such as prior routings to other locations • Bridged taps introduce “DIPS” in the transfer function and produce echoes (return path)

  27. pair i FEXT NEXT pair j 10 10 50 twisted pairs 10 10 2 TPs USA cable Europe cable Crosstalk • Due to capacitive and inductive coupling • NEXT and FEXT introduce coloured noise • Near End Crosstalk : NEXT ~ f 3/2 • Far End Crosstalk : FEXT ~ |A(f)| 2 L f 2

  28. Radio Frequency Interference (RFI) • RFI pick up from Long & Medium wave broadcast transmission • more sensible for overhead cables • EMC legislation • the network transmission system does not interfere with radio transmission • this places a limit on the strength of the signal which may be sent on the line • Impulse Noise

  29. ISDN • 2B1Q • 2B+D (144 kbps) : BRA (Basic Rate Access) • 23B+D (or 30B+D) : PRA (Primary Rate Access) • “ISDN은 결코 사라지지 않는다” • 1992년 망에 도입, 1994년부터 KT에서 사업시작 • 지금까지의 문제점 • 통화권 단위별 ISDN 교환기 미확보 및 서비스의 품질 불안정 • 단말기 가격의 고가 • PSTN에서 ISDN으로의 전환시 기존번호 승계 불가 • 전망 • 98년 말 약 4만 가입자 (일본 600만), 99년 약 20만 예정 • 복합 TA (NT,TA,PC카드) 약 15만원대로 하락 • 인터넷 확산으로 백본망 정비 전까지는 제일 좋은 솔루션 • 정부는 2002년까지 1200만 회선 요구 (5조 4천억원 소요) • AO/DI (Always ON/ Dynamic ISDN): 월 2만원 정액제 추진

  30. xDSL • Applications • Comparisons of xDSLs • HDSL • SDSL • ADSL • UADSL • VDSL • Line Codes - 2B1Q, DMT, QAM, CAP, QPSK • Line Code Battle : DMT vs. CAP • Standardization • Market forecast

  31. High speed xDSL application • Internet Access • High speed internet access to residential and business area • Intranet access in order to link their remote office / branch office (ROBO) • Low cost, high throughput, LAN-to-LAN connectivity (remote LAN Access) • Telecommuting • SOHO (Small Office / Home office) • OD(on-demand) like application • VOD, Home shopping, Tele-education etc. • Interactive TV • Frame Relay / ATM Network Access • xDSL operates at the physical layer • Leased Line Provisioning (HDSL/SDSL) • replacing conventional T1/E1 leased line • FTTC using VDSL

  32. High speed xDSL application • Application Bandwidth Requirements * Acceptable response time < 3.0 sec

  33. Comparisons of xDSL Central Office (PSTN) End User (POTS) TP (2 pairs) CO Repeater Line Repeater Line Repeater T1/E1 0.3~1km 1~1.8 km 0.3~1km End User (POTS) Central Office (PSTN) TP (2 pairs) HDSL CO Unit HDSL RT Unit HDSL End User (Video) Headend (Video) ADSL CO Unit TP (1 pair) ADSL RT Unit ADSL PSTN POTS End User (Video) Headend (Video) Optical Network Unit TP (1 pair) VDSL CO Unit VDSL RT Unit VDSL SPF PSTN POTS

  34. Comparisons of DSL Technologies * Distance for 0.5 mm (24 gauge) TP wires

  35. HDSL • HDSL (High data rate Digital Subscriber Line) • T1 or E1 rate with 2 pairs • 2B1Q Modulated, CAP, DMT • 기존 PCM구간 중계기 없이 대체 • 0.5mm 선로기준으로 2B1Q: 3.6km, CAP:5.5km 전송 가능 • 국내 약 2만 6천 구간 포설 (98년 말 기준) • 가입자들로부터 광으로의 전환을 요청 받고 있는 실정임 • 동일선로 다발 안에 대량으로 공급되는 경우 상호간섭에 의한 문제점 발생 • 국내기술현황 • 초기에는 주로 중소기업체의 주문자상표방식으로 납품되었으며 형식승인이나 시험검사 절차를 통함 • 96년부터 2B1Q 방식의 국내 개발품을 시작으로 97년 부터는 CAP방식으로 상당량의 수량이 설치 운용중임 • 국외기술현황 • 췹레벨 기술보유: PairGain, Rockwell, Adtran, Globespan • 시스팀 레벨 기술 보유: PairGain, Metalink, Cooper Mountain

  36. SDSL • SDSL (Symmetrical Digital Subscriber Line) • 또는 SHDSL이라고도 불림 • T1 or E1 rate with single pair • video conferencing, LAN interconnection, SOHO • 초기에는 768kbps급의 장치가 많이 출시되었으나 최근에는 160kbps부터 2,048kbps 까지 여러 데이타를 허용하는 MDSL로 발전 • every major vendor (Paradyne)

  37. ADSL • ADSL (Asymmetric Digital Subscriber Line) • Internet, VOD like application (asymmetric bandwidth) • ~6-8 Mbps (down), 64 kbps (up) • 1995년 DMT방식이 ANSI T1.413으로 먼저 표준화 되었으나, Lucent의 CAP방식이 먼저 출시되어 시장선점 • 국내서비스현황 • 1994.11-1995.12 반포전화국에서 Westell의 FlexCAP시스팀으로 VDT시범사업 • 1996-1997 전국5대도시에서 아이비젼 시범사업 • 1998 서울,부산,대전에서 1200가입자를 대상으로 고속 인터넷 시범사업 • 현재 ISDN과 ADSL 중 주력상품을 놓고 고민 중 • 본격적인 사업은 ITU-T표준이 확정되는 7월 이후에 추진될 예정 • 정통부 ‘정보대국 기반구축을 위한 선도사업’계획에 의하면 2002년까지 초 중고생 220만 명을 대상으로 교육정보화 사업과 우체국 전자상거래 추진 예정

  38. ADSL • ADSL (Asymmetric Digital Subscriber Line) • 개발업체 동향 • 대우통신: Alcatel과의 기술제휴, 한국통신 및 하나로통신에 공급 • LG정보통신: CAP,DMT 방식 기술확보 • 성미전자: Westell사와 기술제휴 UADSL 타겟 • 현대전자: ADI췹셋을 이용 DMT방식으로 개발완료 • 삼성전자: DMT방식 개발, 정보통신부 국책과제로 삼성종합기술원에서 UADSL 췹셋개발중 • 요금책정: 7만원대 예상, 타사업자와의 경쟁 • Unbundling issue • every major vendor (GlobeSpan) • * RADSL(Rate Adaptive DSL): 가입자 회선의 상황에 따라 속도조절

  39. ADSL • Asymmetric bi-directional digital subscriber line • multimedia services environment • wideband downstream • bi-directional data stream • POTS (Plain Old Telephone Service) • Environments • one twisted pair (nonloaded) • upto 18 kft (ADSL I: 1.5Mbps) ADSL (Down) ISDN Power Spectra POTS ADSL (Up) 4 10 80 90 100 400 4

  40. UADSL • UADSL (Universal ADSL) • CDSL (Consumer Digital Subscriber Line) - Rockwell, Nortel • Rockwell(CAP), Lucent’s WildWire(DMT), MVP-Paradyne • 1Mbps modem technology to facilitate residential DSL deployment • 댁내 재배선으로 의한 문제점을 해결하기 위해 가입자측 POTS splitter의 저역통과 필터 삭제 • 전화기의 off-hook에 따른 fast retrain 절차 필요 • 국내에서는 삼성전자가 췹셋 개발에 이어 UAWG주관의 UADSL 연동성 테스트에 참가 중임 • xDSL관련 솔루션 중에서는 가장 사업성이 있는 것으로 평가되고 있음 • 1998년 10월 ITU-T G.992.2로 determine되었으며 99년 6월에 승인 예정

  41. VDSL • VDSL (Very high data rate Digital Subscriber Line) • drop line with FTTC application • ~155Mbps(down) depending on distance • CAP-16, DMT,QAM (DAVIC) • 아직 표준화가 이루어지지 않고 있음(DAVIC, ANSI T1E1.4, ETSI TM6, FSAN) • 기술적으로는 완성이 되어가고 있지만 business decision이 이루어지지 않은 상태임 • Chipset maker: FSAN Alliance • Savan/Siemens, Texas Instruments, Orkit, Alcatel, Metalink, STMicroelectronics, Broadcom, Aware • 국내동향 • Lucent 췹을 기반으로 FLC-C에 적용 • 삼성전자, ETRI에서 췹셋 개발 중

  42. Line Codes for xDSL • 2B1Q +3 +1 -1 -3 Bits 01 10 11 00 00 11 10 00 01 01 11 01 00 10 Quads -1 +3 +1 -3 -3 +1 +3 -3 -1 -1 +1 -1 -3 +3

  43. xtalk DMT (1) • DMT 방식의 장점 • 각각의 선로별로 그 상태에 따라, 최적의 전송성능을 가질 수 있도록 각 서브 채널별로 적정 비트 할당 TWISTED-PAIR Bits/chan Bits/chan Atten Frequency Frequency Frequency TWISTED-PAIR with TAP, AM/RF, and XTALK Atten Bits/chan Bits/chan AM TAP Frequency Frequency Frequency

  44. T’=TDMT/2N Transmitted signal Encoder and buffer b=RT Parallel to serial converter R b/s 2N Point IDFT LPF DAC 2N Times Domain Samples N QAM Symbols Noise Channel S T’ Decoder and buffer b=RT Serial to Parallel converter R b/s LPF 2N Point DFT DAC Received signal 2N Times Domain Samples N QAM Symbols DMT (2) • DMT Transceiver Block Diagram

  45. DMT (3) • pros • frequency efficiency • overall frequency spectrum become flat • symbol length per subchannel becomes longer • frequency selective noise can be avoided • cons • complex • more power consumption (more heat) • timing and synchronization become critical factors • ANSI standard, but market fail

  46. Line Codes for xDSL • 16QAM : Downstream in DAVIC VDSL

  47. Inphase filter Encoder Input signal DAC LPF + Quadrature filter C H A N N E L Inphase filter Decoder Decision device Output signal ADC Quadrature filter CAP (1) • Carrierless Amplitude/Phase Modulation • Bellcore & AT&T • CAP Transceiver

  48. 01 00 11 10 CAP (2) • Encoding (16 CAP) • map four data bits into a symbol t ... b2 b3 b0 b1 b2 b3 b0 b1 b2 b3 b0 b1... quadrant point within quadrant symbol Qn 11 01 +3 10 11 b2 b3 current state 00 10 +1 01 00 -3 -1 +3 +1 In 01 00 10 00 -1 11 10 -3 01 11

  49. Line Codes for xDSL • QPSK: Upstream transmission in DAVIC VDSL

  50. 교환기 Splitter Splitter 0~4 kHz PSTN 가입자선로 DSLAM Data Comm. Network ATU-R ATU-C T1.413 Issue 2 : 하향 25 ~ 1104 kHz, 상향 25 ~ 138 kHz UADSL : 하향 138 ~ 552 kHz, 상향 25 ~ 138 kHz) 가입자선로 UADSL-R * DSLAM : Digital Subscriber Lines Access Multiplexer * ATU-C : ADSL Transceiver Unit, Central * ATU-R : ADSL Transceiver Unit, Remote * UADSL의 경우 Splitterless ADSL 가입자망 구성도

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