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BASIC TELECOMMUNICATIONS

BASIC TELECOMMUNICATIONS . DSL (Digital Subscriber Loop). BASIC TELECOMMUNICATIONS . The first DSL connections available to the public was offered in the late 1990s.

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BASIC TELECOMMUNICATIONS

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  1. BASIC TELECOMMUNICATIONS DSL (Digital Subscriber Loop)

  2. BASIC TELECOMMUNICATIONS • The first DSL connections available to the public was offered in the late 1990s. • It didn’t become readily accepted until the early 2000s when consumers started becoming frustrated with slow down load speeds through dial up service (AOL) • Many industry professionals argued that DSL was too cost prohibitive and would not gain traction in the public market place

  3. BASIC TELECOMMUNICATIONS • Dial up modems provided maximum down load speeds of up to 56Kbps, however these speeds were rarely ever achieved • With the introduction of DSL, down load speeds of 1.544Mbps were possible 56K dial up modem

  4. BASIC TELECOMMUNICATIONS • Though the equipment (DSL modem) and subscription costs were fairly high compared to dial up DSL became very popular. • Soon ILECs (Incumbent Local Exchange Carriers) had to start building out their networks to meet customer demand for DSL service • As a result, the need for even higher broadband speeds introduced several types of DSL services

  5. BASIC TELECOMMUNICATIONS • DSL (Digital Subscriber Loop) is sometimes called digital subscriber line. • xDSL: the x denotes any type of DSL circuit of which there are several types • DSL was originally developed to operate over POTS lines using the old quad cables already present in residential and small business buildings

  6. BASIC TELECOMMUNICATIONS The different types of DSL circuits are : • ADSL Asymmetrical DSL • HDSL Symmetrical High-Bit-Rate DSL • HDSL2 Second Generation HDSL • ADSL2 Second Generation ADSL • G.SHDSL Single-Pair HDSL • VDSL Very High Speed DSL • VoDSL Voice over DSL

  7. BASIC TELECOMMUNICATIONS • When we look at the different DSL designations you’ll notice that they are asymmetrical or symmetrical • Asymmetrical is a different bandwidth speed upstream from the bandwidth speed downstream • Symmetrical is the same bandwidth speed in both directions, upstream and downstream

  8. BASIC TELECOMMUNICATIONS Here is a sample speed test showing download and upload speeds Is this connection asymmetrical or symmetrical?

  9. BASIC TELECOMMUNICATIONS • Bandwidth in it’s simplest terms is info carrying capacity

  10. BASIC TELECOMMUNICATIONS • Upstream is information sent from your computer to another location on the internet • Downstream is information you down load from another source on the internet

  11. BASIC TELECOMMUNICATIONS • DSL is faster than basic ISDN interface and less costly than a T-1 trunk • DSL transmits data in packets at higher frequencies than those used for voice • This makes it possible in ADSL to send and receive data at the same time an analog voice call is taking place on the same pair of wires

  12. BASIC TELECOMMUNICATIONS DSL circuits require the use of special modems and line splitters at the subscriber end

  13. BASIC TELECOMMUNICATIONS The voice traffic is processed through the PSTN and data packets are routed through other high speed networks

  14. BASIC TELECOMMUNICATIONS • DSL operation is limited by distances of two to three miles from the CO • The distance limitations can be overcome by the installation of a DSLAM (DSL access multiplexer) within three miles of the customer’s premises • DSL is delivered over copper pairs and many Cos have been upgrading their infrastructure to fiber optics which doesn’t support DSL circuits

  15. BASIC TELECOMMUNICATIONS Below is a list of common DSL circuits listing their different characteristic

  16. BASIC TELECOMMUNICATIONS How is it possible for a voice conversation to take place at the same time as surfing the web on a DSL connection that operates on only one pair of wires? http://en.wikipedia.org/wiki/Digital_subscriber_line

  17. BASIC TELECOMMUNICATIONS • Today more and more residential and enterprise companies are using cable internet services for their low cost high speed data connection. • Cable providers can utilize existing HFC (Hybrid Fiber Coax) cable infrastructures to provide high speed broad band data services that are not subjected to the same limitations as DSL

  18. BASIC TELECOMMUNICATIONS Coax cable is capable of operating in the GHz range and regularly used for CATV it operates at 900MHz to deliver voice, data and video services over the same cable COAX CABLE IS UNBALANCED TRANSMISSION, ALL OF THE SIGNAL TRAVELS THRU THE CENTER CONDUCTOR AND AS RESULT IT CREATES A LOT OF NOISE

  19. BASIC TELECOMMUNICATIONS • VoDSL is different from other DSL circuits because it converts analog voice signals to digitized data packets and is overlaid onto symmetrical DSL • This allows the data to be transferred over high speed data networks like the internet which eliminates the need for it to be routed through the PSTN • This type of circuit allows up to 24 calls at a time while leaving room for data transmission

  20. BASIC TELECOMMUNICATIONS • This makes VoDSL similar to VoIP (Voice over Internet Protocol) without the need for an expensive T-1 circuit • SHDSL and HDSL2 are the preferred choice for a VoDSL circuit • With this technology when the call volume is low the data capacity increases and when call volume is high the data capacity decreases

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