1. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-1 Raymond Panko’s Business Data Networks and Telecommunications, 7th edition May only be used by adopters of the book Telecommunications Chapter 6 Updated January 2009

2. © 2009 Pearson Education, Inc. Publishing as Prentice Hall6-2 6-1: Elements of the Public Switched Telephone Network (PSTN) 1. Customer Premises Equipment 1. Customer Premises Equipment Customer premises Equipment (CPE) consists of telephones, wires, and other infrastructure It is owned by the customer.

3. © 2009 Pearson Education, Inc. Publishing as Prentice Hall6-3 6-1: Elements of the PSTN End Office Switch 2. Access Line (Local Loop) 2. Access Line (Local Loop) The Access System consists of the access line to the customer (called the local loop) and termination equipment at the end office (nearest telephone office switch). 1. Customer Premises Equipment

4. © 2009 Pearson Education, Inc. Publishing as Prentice Hall6-4 6-1: Elements of the PSTN 3. Transport Core 3. Trunk Line 3. Switch The Transport Core connects end office switches and core switches. Trunk lines connect switches.

5. © 2009 Pearson Education, Inc. Publishing as Prentice Hall6-5 6-1: Elements of the PSTN 4. Signaling System Transport is the actual transmission of voice. Signaling is the control of calling (setup, teardown, billing, etc.). SS7 in the United States, C7 in Europe

6. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-6 6-2: Customer Premises Equipment at a Business Site Most businesses have a PBX (private branch exchange). It acts like an internal switchboard Businesses use 4-pair UTP for in-building telephone wiring.

7. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-7 6-4: Circuit Switching

8. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-8 Analog versus Digital Transmission

9. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-9 6-9: Analog Telephone Transmission Speaking creates pressure waves, which hit the microphone in the handset. The microphone generates an analogous electrical signal. This is called an analog signal. Handset

10. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-10 Figure 6-9: The PSTN: Mostly Digital with Analog Local Loops Today, everything is digital except for the local loop access line and residential telephones. The actual local loop line can carry either analog or digital signals, but the equipment at both ends is analog.

11. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-11 Figure 6-10: Codec at the End Office Switch A codec at the end office translates between residential analog and PSTN digital signaling. ADC = analog to digital conversion DAC = digital to analog conversion

12. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-12 Cellular Telephony

13. © 2009 Pearson Education, Inc. Publishing as Prentice Hall © 2011 Pearson Education, Inc. Publishing as Prentice Hall 13 6-15: Cellular Technology A geographical area is divided into areas called cells. Each cell has a cellsite with a transmitter/receiver. A geographical area is divided into areas called cells. Each cell has a cellsite with a transmitter/receiver.

14. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-14 6-15: Cellular Telephony Cellsites

15. © 2009 Pearson Education, Inc. Publishing as Prentice Hall © 2011 Pearson Education, Inc. Publishing as Prentice Hall 15 6-15: Cellular Technology The route of a cellular telephone call to a wireline customer.

16. © 2009 Pearson Education, Inc. Publishing as Prentice Hall © 2011 Pearson Education, Inc. Publishing as Prentice Hall 16 6-15: Cellular Technology The MTSO constantly monitors and controls all cellsites in a cellular system.

17. © 2009 Pearson Education, Inc. Publishing as Prentice Hall © 2011 Pearson Education, Inc. Publishing as Prentice Hall 17 6-15: Cellular Technology In handoff, a mobile phone moves from one cell to another cell in the same city. In roaming, a mobile phone is taken to a different city. In handoff, a mobile phone moves from one cell to another cell in the same city. In roaming, a mobile phone is taken to a different city.

18. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-18 6-16: Handoff and Roaming in 802.11 Wireless Networking and Cellular Telephony 802.11 WLANsCellular Telephony RelationshipHandoff and roaming mean the same thing Handoff and roaming mean different things Handoffs (means the same in both) Wireless host travels between access points in an organization Mobile phone travels between cellsites in the same city Roaming (means different things) Wireless host travels between access points in an organization Mobile phone travels to a different city

19. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-19 Voice over IP (VoIP)

20. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-20 6-17: Voice over IP (VoIP) VoIP carries telephone calls over LANs and the Internet This reduces cost.

21. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-21 6-17: Voice over IP (VoIP) The user either has a PC with multimedia hardware and VoIP software or an IP telephone that can be plugged into an IP network via a wall jack. Either must have a codec The user either has a PC with multimedia hardware and VoIP software or an IP telephone that can be plugged into an IP network via a wall jack. Either must have a codec

22. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-22 Wired “Last Mile” Services Telephone Modems ADSL Modem Service Cable Modem Service Fiber to the Home

23. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-23 Figure 6-18: Residential Internet Access Services Telephone Modems Asymmetric Digital Subscriber Line (ADSL) Cable Modem Service Fiber to the Home (FTTH) Note: Speeds and Prices Change Rapidly

24. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-24 Telephone Modem Connection to an ISP Telephone modems –Convert digital computer signals to analog and send these over the telephone access line –They also convert incoming analog signals into digital signals for the computer Telephone Modem Telephone Line Digital Computer Signal: 1011001101010 Analog Telephone Signal:

25. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-25 Telephone Modem Connection to an ISP

26. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-26 6-20: “Traditional” Technologies for the Last Mile Telephone modems –Limited to 33.6 kbps sending / 56 kbps receiving –Cannot use your telephone for calls while using the telephone modem

27. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-27 Figure 6-21: Asymmetric Digital Subscriber Line (ADSL) Like telephone modems, ADSL also uses the existing 1-pair voice-grade UTP line going to the home; but it offers higher speeds than telephone modems

28. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-28 Figure 6-21: Asymmetric Digital Subscriber Line (ADSL) 1. Subscriber needs an ADSL modem. Also needs a splitter for each telephone wall outlet. 2. Telephone carrier needs a digital subscriber line access multiplexer (DSLAM) to separate the two signals.

29. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-29 Figure 6-21: Asymmetric Digital Subscriber Line (ADSL) Unlike telephone modems, ADSL service provides simultaneous voice and data transmission. Downstream Data Up to 3 Mbps

30. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-30 6-21: Asymmetric Digital Subscriber Line (ADSL) Speed is asymmetric. Faster downstream (to home) speed than upstream (from the home) speed. This is ideal for World Wide Web downloads. Speeds are increasing rapidly in both directions.

31. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-31 6-22: Cable Modem Service Cable modem service is provided by the cable television company, not by a telephone company Generally is faster than ADSL but also more expensive Cable Modem

32. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-32 6-22: Cable Modem Service Optical fiber brings signals to and from the neighborhood. Thick coaxial cables carry signals in the neighborhood.

33. © 2009 Pearson Education, Inc. Publishing as Prentice Hall 6-33 6-22: Cable Modem Service Thin coaxial drop cables carry signals from the trunk cable to individual residences. Subscriber needs a cable modem to receive data service.

34. © 2009 Pearson Education, Inc. Publishing as Prentice Hall Fiber to the Home (FTTH) Some carriers are beginning to replace their 1-pair voice grade UTP residential wiring with optical fiber This is called fiber to the home or fiber to the premises Download speeds of 100 Mbps or more Substantially more expensive than DSL service 6-34