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Signaling and Switching

Signaling and Switching. Chapter 6. Objectives. In this chapter, you will learn to: Define modulation and explain its four basic versions Explain the different types of multiplexing techniques, their benefits, and hardware requirements

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Signaling and Switching

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  1. Signaling and Switching Chapter 6 Tamra Dean -- Modified by: Brierley

  2. Objectives In this chapter, you will learn to: • Define modulation and explain its four basic versions • Explain the different types of multiplexing techniques, their • benefits, and hardware requirements • Discuss the fundamental types of switching used in voice and data communications • Identify the differences between local and tandem switching • Describe modern signaling techniques used to route calls to their destination Tamra Dean -- Modified by: Brierley

  3. Modulation • A technique for processing signals in which two waves are combined to produce a wave that possesses characteristics of both and can be decoded to separate these characteristics. • Information wave - the wave containing the signal you want to transmit. • Carrier wave - the wave that is modulated, and whose properties are constant and known to both the sender and receiver. • Guided waves - waves that are bound to a carrier wave’s frequency. Tamra Dean -- Modified by: Brierley

  4. Modulation • Modulator - the device that imposes the information signal on the carrier signal at the transmission end. • Demodulator - separates the information from the carrier signal at the receiving end. • Modem - a device used to convert digital into analog signals and analog into digital signals. Tamra Dean -- Modified by: Brierley

  5. Modulation Tamra Dean -- Modified by: Brierley

  6. Amplitude Modulation Tamra Dean -- Modified by: Brierley

  7. Amplitude Modulation Tamra Dean -- Modified by: Brierley

  8. Frequency Modulation • A method of modulation in which the frequency of the carrier signal is modified by the addition of the information signal. • Frequency shift keying (FSK) - when FM signals are converted into digital signals, the differing frequencies are conveyed as either 0s or 1s. Tamra Dean -- Modified by: Brierley

  9. Frequency Modulation Tamra Dean -- Modified by: Brierley

  10. Frequency Modulation Tamra Dean -- Modified by: Brierley

  11. Phase Modulation Tamra Dean -- Modified by: Brierley

  12. Phase Modulation Tamra Dean -- Modified by: Brierley

  13. Phase Modulation Tamra Dean -- Modified by: Brierley

  14. Pulse Code Modulation (PCM) • The process of converting analog signals into digital signals • Sampling - the first step in converting analog signals to digital signals is to measure the amplitude of an analog signal at multiple instants. • The higher the sampling rate, the more closely the digital signal resembles the original analog signal. Tamra Dean -- Modified by: Brierley

  15. Pulse Code Modulation (PCM) Tamra Dean -- Modified by: Brierley

  16. Quantizing • To create a replica of the audio wave in digital format, each sample is converted into its binary equivalent in a process called quantizing. • One problem with quantizing is that it introduces noise. This occurs because a signal composed of quantized values is not as precise as the original analog signal, which is made of one continuous wave. • Companding - This process of compressing and expanding a signal. Tamra Dean -- Modified by: Brierley

  17. Quantizing Tamra Dean -- Modified by: Brierley

  18. Quantizing Tamra Dean -- Modified by: Brierley

  19. Frequency Division Multiplexing (FDM) • Frequency division multiplexing (FDM) - a method of sending multiple analog signals simultaneously over one channel by separating the channel into subchannels, or bands. • Guardband - a narrow range of unused frequency between each band’s frequency. It ensures that signals do not interfere with each other. Tamra Dean -- Modified by: Brierley

  20. Frequency Division Multiplexing (FDM) Tamra Dean -- Modified by: Brierley

  21. Time Division Multiplexing (TDM) Tamra Dean -- Modified by: Brierley

  22. Time Division Multiplexing (TDM) Tamra Dean -- Modified by: Brierley

  23. Statistical Multiplexing Tamra Dean -- Modified by: Brierley

  24. Wavelength Division Multiplexing Tamra Dean -- Modified by: Brierley

  25. Switching • A method of establishing connections and sending information between nodes on a network. • Circuit switching - establishing a connection between two devices on a network, before they begin transmitting data. • The advantage of circuit switching is that it guarantees two devices exclusive use of a communications channel. Tamra Dean -- Modified by: Brierley

  26. Switching Tamra Dean -- Modified by: Brierley

  27. Message Switching Tamra Dean -- Modified by: Brierley

  28. Packet Switching Tamra Dean -- Modified by: Brierley

  29. Switching Systems • The combined collection of hardware and software that establishes connections between lines and trunks in order to complete calls. • Although makes and models differ between manufacturers, all modern switches share four essential elements: • Switching matrix • Line or trunk circuits • Central control computer • Common equipment Tamra Dean -- Modified by: Brierley

  30. Local Switching Systems • A local switch performs the following functions: • Provides dial tone to a local subscriber • Accepts and interprets signals (including off-hook notification, dial tones, and so on) from the local subscriber • Receives signals from the destination’s local switch about when to terminate the call • Records local subscriber billing information • Stores information about subscribers (such as what type of service they have chosen) in a subscriber database • Tests and maintains the subscriber’s local loop Tamra Dean -- Modified by: Brierley

  31. Switching an Intra-Office Call Tamra Dean -- Modified by: Brierley

  32. Tandem Switching • A tandem switch may perform the following functions: • Provide termination for trunks at Class 1, 2, 3, and 4 central offices • Gather and transmit information about telephone network traffic and congestion • Determine the fastest path over the PSTN for long-distance calls • Carry data and voice signals between central offices • Test and maintain trunks • Assist in trunk configuration Tamra Dean -- Modified by: Brierley

  33. Tandem Switching Tamra Dean -- Modified by: Brierley

  34. Lucent’s ESS Switch Tamra Dean -- Modified by: Brierley

  35. Nortel’s DMS Switch Tamra Dean -- Modified by: Brierley

  36. Nortel’s DMS Switch Tamra Dean -- Modified by: Brierley

  37. Switch Signaling • The exchange of information between the components of a telephone network or system for the purposes of establishing, monitoring, or releasing phone circuits as well as controlling system operations. • Switch-signaling functions include: • Transmitting Address Information • Supervising • Transmitting Information Tamra Dean -- Modified by: Brierley

  38. Subscriber Loop Signaling • The exchange of information about a telephone circuit over the local loop. • The primary types of supervisory signals include: • Idle circuit • Busy circuit • Seizure • Disconnect Tamra Dean -- Modified by: Brierley

  39. Common Channel Signaling (CCS) Tamra Dean -- Modified by: Brierley

  40. Signaling System No. Seven (SS7) Tamra Dean -- Modified by: Brierley

  41. Summary • Modulation is a signal-processing technique in which an information wave is imposed on (combined with) a carrier wave to create a unique wave pattern. • Common methods of multiplexing include frequency division multiplexing (FDM), time division multiplexing (TDM), statistical multiplexing, and wave division multiplexing (WDM). • Switching is a method of establishing connections and sending information between nodes on a network. Tamra Dean -- Modified by: Brierley

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