Networks rely on multiplexing to increase the amount of data that can be

Networks rely on multiplexing to increase the amount

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Networks rely on multiplexing to increase the amount of data that can be transmitted in a given time span over a given bandwidth - Time division multiplexing (TDM) o Divides channel into multiple time intervals Statistical multiplexing Transmitter assigns slots to nodes
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According to priority, need More efficient than TDM Frequency division multiplexing (FDM) Unique frequency band for each communications subchannel Cellular telephone transmission DSL Internet access Wavelength division multiplexing (WDM) One fiber-optic connection Carries multiple light signals simultaneously Dense wavelength division multiplexing (DWDM) Used on most modern fiber-optic networks Extraordinary capacity Networking Media - Match networking needs with media characteristics when selecting transmission media Physical media characteristics: Throughput, Cost, Noise immunity, Size and scalability, Connectors and media converters Throughput: Most significant factor in choosing transmission method Causes of throughput limitations Laws of physics Signaling and multiplexing techniques Noise Devices connected to transmission medium Fiber-optic cables allow faster throughput Compared to copper or wireless connections
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Cost: Precise costs difficult to pinpoint Media cost dependencies Existing hardware, network size, labor costs Variables influencing final cost Installation cost New infrastructure cost versus reuse Maintenance and support costs Cost of lower transmission rate affecting productivity Cost of downtime Cost of obsolescence Noise Immunity: Noise distorts data signals Distortion rate dependent upon transmission media Fiber-optic: least susceptible to noise Limit noise impact on network Cable installation Far away from powerful electromagnetic forces Select media protecting signal from noise Size and Scalability: Three specifications Maximum nodes per segment Maximum segment length Maximum network length Maximum nodes per segment dependency Attenuation and latency Maximum segment length dependency Attenuation and latency plus segment type Segment types Populated: contains end nodes Unpopulated: no end nodes Also called link segment Segment length limitation After certain distance, signal loses strength Cannot be accurately interpreted Connectors and Media Converters: Connectors Hardware connecting wire to network device Specific to particular media type Affect costs Installing and maintaining network Ease of adding new segments or nodes Technical expertise required to maintain network Media converter Hardware enabling networks or segments running on different media to interconnect and exchange signals Cabling Coaxial Cable: Central metal core (often copper) surrounded by: Insulator Braided metal shielding (braiding or shield)
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