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EVOLUTION OF SDH TECHNOLOGY. PLESIOCHRONOUS DIGITAL HIERARCHY (PDH). PULSE CODE MODULATION. Voice Frequency ranges upto 4 Khz Sampling the Voice Signal @ 8 Khz (Double the Max. Frequency) 8 bits per sample Digital Bit Rate: 8Khz X 8 = 64 Khz. BUILDING UP THE BASE STREAM (2MB).
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PULSE CODE MODULATION • Voice Frequency ranges upto 4 Khz • Sampling the Voice Signal @ 8 Khz (Double the Max. Frequency) • 8 bits per sample • Digital Bit Rate: 8Khz X 8 = 64 Khz
BUILDING UP THE BASE STREAM (2MB) • 30 Voice Channels @ 64 Khz • One channel for Frame (64 K) • One channel for Signaling (64 K) • Total number of Channels = 32 • Bit Rate: 32 X 64 K= 2048 Khz (2Mb)
PDH BIT RATES • E1-2048 Kbps (2Mb) [30 Voice Channel] • E2-8448 Kbps (8Mb) [120 Voice Channel] • E3-34368 Kbps (34Mb) [480 Voice Channel] • E4-139264 Kbps (140Mb) [1920 Voice Channel]
PDH PRODUCTS MULTIPLEXERS: • M12 MUX:4E1 Streams Multiplexed to One E2 • M23 MUX:4E2 Streams Multiplexed to One E3 • M34 MUX:4E3 Streams Multiplexed to One E4
PDH PRODUCTS Contd…… OPTICAL: • OPTICAL LINE TERMINAL EQUIPMENT (OLTE)-8Mb, 34Mb, 140Mb. • OPTICAL REGENERATOR EQUIPMENT- 34 Mb,140Mb. OPTIMUX: • SINGLE SHELF CONTAINS BOTH MUX AND OLTE
ITU RECOMMENDATIONS - PDH • G.701 Vocabulary of digital transmission and multiplexing, and pulse code modulation (PCM) terms • G.702 Digital hierarchy bit rates • G.703 Physical/electrical characteristics of hierarchical digital interfaces • G.704 Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels • G.705 Characteristics of plesiochronous digital hierarchy (PDH) equipment functional blocks • G.706 Frame alignment and cyclic redundancy check (CRC) procedures relating to basic frame structures defined in Recommendation G.704
LIMITATIONS IN PDH • Different Standards • Systems operates in its own Clock • Proprietary Coding Mechanisms Making Inter-Operas Ability of System Between Different Vendors • Not Transparent • Protection Schemes are not available • Ring, Hub Configuration not possible
WHY SDH? • High Transmission Rates • Simplified Add & Drop Function • High Availability and Capacity Matching • Reliability • Future Proof Platform for New Services • Interconnection
SYNCHRONOUS NETWORK Contd… • Regenerators • Terminal Multiplexers • Add-drop Multiplexers • Digital X-Connect • Network Management System
CLOCK SUPPLY HIERARCHY • Primary Reference Clock (PRC) Accuracy : 1 x 10-11 ppm • Synchronisation Supply Unit (SSU) Accuracy : 1 x 10-9 ppm • Synchronisation Equipment Clock (SEC) Accuracy : 4.6 x 10-6 ppm
AUTOMATIC PROTECTION SWITCHING(APS) • LINEAR PROTECTION • UNIDIRECTIONAL RINGS • BI-DIRECTIONAL RINGS
DENSE WAVELENGTH DIVISIONMULTIPLEXING DWDM is a Fiber Optic Transmission technique that employs light wavelengths to transmit data Parallel-by-bit or Serial by Character.
CHALLENGES IN OPTICAL NETWORKS • Increased service Needs • Fiber exhaust • Layered bandwidth management
SOLUTIONS • Laying more fiber • Time Division Multiplexing (TDM) • Dense wavelength Division Multiplexing (DWDM)
LAYING MORE FIBER • Economic solution where cost of fiber laying is minimal • May not be able to provide new services or utilize bandwidth management capability of a unifying optical layer.
MULTIPLEXING TECHNIQUES • TIME DIVISION MULTIPLEXING (TDM) • Synchronous • Asynchronous • WAVE DIVISION MULTIPLEXING (WDM)
COMPONENTS OF A DWDM SYSTEMContd… • Transponder • Multiplexer • Fiber • Amplifier • Demultiplexer • Receiver
ABBREVATION • PMD-POLORIZATION MODE DISPERSION • SPM- SELF PHASE MODULATION • XPM- CROSS PHASE MODULATION • FWM- FOUR WAVE MIXING • RAMAN-STIMULATED RAMAN SCATTERING • BRILLOUIN-STIMULATED BRILLOUIN SCATTERING
ITU RECOMMENDATIONS - DWDM • G.694.1 Spectral grids for WDM applications: DWDM frequency grid • G.694.2 Spectral grids for WDM applications: CWDM wavelength grid • G.695 Optical interfaces for coarse wavelength division multiplexing applications • G.696.1 Intra-domain DWDM applications • G.697 Optical monitoring for DWDM systems • G.698.1 Multichannel DWDM applications with single channel optical interfaces