Utilization of High Bandwidth Channels Martin Weiss

Slide 2 Objectives of this Meeting u Describe multiplexing techniques u Identify the elements of the public telephone network u Describe the organization of the public telephone network

Slide 3 Frequency Division Multiplexing Line 6 Line 5 Line 4 Line 3 Line 2 Line 1 Time Frequency Guard Band Transmission Bandwidth

Slide 4 Time Division Multiplexing Frequency Time  Framing Samples from Lines

Slide 5 North American Digital Multiplex Hierarchy u Common transmission rates –DS0 = 64 kbps –DS1 = Mbps = 24 DS0's –DS3 = Mbps = 28 DS1's = 672 DS0's

Slide 6 ITU Digital Multiplex Hierarchy u Common transmission rates –E0 = 64 kbps –E1 = Mbps = 30 E0's –E2 = Mbps = 120 E0's –E3 = Mbps = 480 E0's –E4 = Mbps = 1920 E0's –E5 = Mbps = 7680 E0's

Slide 7 Structure of Digital Transmission - T1 u Data is organized into Frames u Frames are delimited by a Framing Bit u Frames of frames, called Superframes, are also defined

Slide 8 Structure of a T1 Frame    Channel 1Channel 2Channel 3Channel 24F u Frame length –24 channels * 8 bits/channel = 192 Bits –Add 1 framing bit = 193 Bits

Slide Frame Number Value of Framing Bit Normal T1 Superframe Structure

Slide 10 ESF Frame Structure Frame Number Contents of Framing Bit DDC0DCCD0D1D DDC1DCCD0D1D D - Data Link Bits C - CRC-6 Bits

Slide 11 Components of a T1 Line CSU IXC Network U S E R LEC 2 Network LEC 1 Network CSU U S E R User's CPE

Slide 12 Structure of the Public Network u Technical structure –Telephone network structure –Equipment requirements and configuration u Organizational Structure (US) –Local access –Long distance

Slide 13 Initial Network Structure

Slide 14 Intermediate Network Structure Central Office

Slide 15 Expansion of the Intermediate Structure Central Office Central Office Central Office Central Office

Slide 16 Toll Offices Central Office Central Office Central Office Central Office Toll Office

Slide 17 Switching Hierarchy (Pre- Divestiture) Regional Center Sectional Center Primary Center Toll Center Central Office Local Tandem Office High Usage Trunks

Slide 18 Components of the Public Network Local Loop Switch Multiplexer Switch Multiplexer Transmission System PBX Local Loop Trunk Lines Signalling

Slide 19 Structure of the Public Network (1950s) Inside Wire Local Loop Central Office Tandem Office Tariffed and Regulated Interstate Network StateFederal

Slide 20 Structure of the Public Network (1970s) Tariffed and Regulated Inside Wire Local Loop Central Office AT&T’s Tandem Office OCC’s Tandem Office 2 wire 4 wire PCA Interstate Network Interstate Network StateFederal

Slide 21 Structure of the Public Network (1980s) Tariffed and Regulated Local Loop Central Office “Dominant” IXC’s POP “Non-Dominant” IXC’s POP 4 wire Enhanced Service Provider InterLATA Network InterLATA Network State Federal

Slide 22 Structure of the Public Network (Early 1990s) Tariffed and Regulated Local Loop LEC Central Office “Dominant” IXC’s POP “Non-Dominant” IXC’s POP 4 wire Enhanced Service Provider CAPs/Cable TV/Wireless Operator Services Providers To IXC InterLATA Network InterLATA Network State Federal

Slide 23 Structure of the Network (Late 1990s) Local Loop LEC Central Office IXC’s POP Enhanced Service Provider CAPs CATV Wireless IXC Operator Services Providers To IXC InterLATA Network State Federal InterLATA Network LEC’s POP

Slide 24 Telephone Competition ( ) Local Loop Central Office Tandem Office Interstate Network Local Loop Central Office Tandem Office Bell System Non-Bell Company Local Franchise

Slide 25 Telephone Competition ( ) Local Loop Central Office Tandem Office Interstate Network Local Loop Central Office Bell System Non-Bell Company Tariffed and Regulated State

Slide 26 Signalling in the Telephone Network u Traditional signalling u Modern signalling u Intelligent Network services

Slide 27 Traditional Signalling u Terminal to Switch u Switch to Switch

Slide 28 In-Band Signalling Signalling Path and Message Path

Slide 29 Out-of-Band Signalling Message Path Signalling Path

Slide 30 ITU Signalling System 7 (SS7) u New generation of signalling system u More capable than SS6 (CCIS) u The Integrated Services Digital Network (ISDN) requires SS7

Slide 31 SS7 Services: The Intelligent Network u Extensive Application of SS7 Technology u Custom Local Access Subscriber Services (CLASS) u Advanced Intelligent Network Services –More sophisticated applications of IN services