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Utilization of High Bandwidth Channels. Martin Weiss. Objectives of this Meeting. Describe multiplexing techniques Identify the elements of the public telephone network Describe the organization of the public telephone network. Frequency Division Multiplexing. Frequency. Line 6. Line 5.
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Utilization of High Bandwidth Channels Martin Weiss
Objectives of this Meeting • Describe multiplexing techniques • Identify the elements of the public telephone network • Describe the organization of the public telephone network
Frequency Division Multiplexing Frequency Line 6 Line 5 Line 4 Transmission Bandwidth Line 3 Line 2 Line 1 Guard Band Time
Time Division Multiplexing Frequency Framing 1 2 3 4 5 6 1 2 3 4 5 6 Time Samples from Lines
North American Digital Multiplex Hierarchy • Common transmission rates • DS0 = 64 kbps • DS1 = 1.544 Mbps = 24 DS0's • DS3 = 44.736 Mbps = 28 DS1's = 672 DS0's
ITU Digital Multiplex Hierarchy • Common transmission rates • E0 = 64 kbps • E1 = 2.048 Mbps = 30 E0's • E2 = 8.448 Mbps = 120 E0's • E3 = 34.368 Mbps = 480 E0's • E4 = 139.264 Mbps = 1920 E0's • E5 = 565.148 Mbps = 7680 E0's
Structure of Digital Transmission - T1 • Data is organized into Frames • Frames are delimited by a Framing Bit • Frames of frames, called Superframes, are also defined
Structure of a T1 Frame • Frame length • 24 channels * 8 bits/channel = 192 Bits • Add 1 framing bit = 193 Bits F Channel 1 Channel 2 Channel 3 Channel 24
Normal T1 Superframe Structure 1 0 0 0 1 1 0 1 1 1 0 0 Value of Framing Bit 1 2 3 4 5 6 7 8 9 10 11 12 Frame Number
ESF Frame Structure Contents of Framing Bit D C D 0 D C D 0 D C D 1 D C D 0 D C D 1 D C D 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Frame Number D - Data Link Bits C - CRC-6 Bits
Components of a T1 Line User's CPE U S CSU CSU LEC 1 Network E R U S CSU E R IXC Network CSU LEC 2 Network
Structure of the Public Network • Technical structure • Telephone network structure • Equipment requirements and configuration • Organizational Structure (US) • Local access • Long distance
Intermediate Network Structure Central Office
Expansion of the Intermediate Structure Central Office Central Office Central Office Central Office
Toll Offices Central Office Central Office Toll Office Central Office Central Office
Switching Hierarchy (Pre-Divestiture) RegionalCenter Sectional Center Primary Center Toll Center High Usage Trunks Local Tandem Office Central Office
Components of the Public Network Local Loop Multiplexer Multiplexer Local Loop Switch Switch Transmission System Trunk Lines Signalling PBX
Structure of the Public Network (1950s) State Federal Tariffed and Regulated Local Loop Interstate Network Inside Wire Central Office Tandem Office
Structure of the Public Network (1970s) State Federal Tariffed and Regulated AT&T’s Tandem Office Inside Wire Central Office Interstate Network 4 wire Local Loop PCA 2 wire Interstate Network OCC’s Tandem Office
Structure of the Public Network (1980s) Federal State Tariffed and Regulated “Dominant” IXC’s POP Central Office 4 wire InterLATA Network Local Loop 4 wire Enhanced Service Provider InterLATA Network “Non-Dominant” IXC’s POP
Structure of the Public Network (Early 1990s) Operator Services Providers Federal CAPs/Cable TV/Wireless To IXC State LEC Central Office Tariffed and Regulated “Dominant” IXC’s POP 4 wire InterLATA Network Local Loop 4 wire InterLATA Network Enhanced Service Provider “Non-Dominant” IXC’s POP
Structure of the Network (Late 1990s) Operator Services Providers CAPs CATV Wireless IXC Federal To IXC LEC Central Office IXC’s POP InterLATA Network Local Loop State LEC’s POP InterLATA Network Enhanced Service Provider
Telephone Competition (1893-1912) Non-Bell Company Local Franchise Central Office Tandem Office Local Loop Interstate Network Local Loop Central Office Tandem Office Bell System
Telephone Competition (1912-1921) Non-Bell Company State Central Office Local Loop Tariffed and Regulated Interstate Network Local Loop Central Office Tandem Office Bell System
Signalling in the Telephone Network • Traditional signalling • Modern signalling • Intelligent Network services
Traditional Signalling • Terminal to Switch • Switch to Switch
In-Band Signalling Signalling Path and Message Path
Out-of-Band Signalling Message Path Signalling Path
ITU Signalling System 7 (SS7) • New generation of signalling system • More capable than SS6 (CCIS) • The Integrated Services Digital Network (ISDN) requires SS7
SS7 Services: The Intelligent Network • Extensive Application of SS7 Technology • Custom Local Access Subscriber Services (CLASS) • Advanced Intelligent Network Services • More sophisticated applications of IN services