statistical multiplexing o transmitter assigns slots to nodes according to

Statistical multiplexing o transmitter assigns slots

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statistical multiplexing o transmitter assigns slots to nodes according to priority need o more efficient than TDM - frequency division multiplexing (FDM) o unique frequency band for each communications subchennel o cellular telephone transmission o DSL internet access - Wavelength division multiplexing (WDM) o One fiber optic connection o Carries multiple light signals simultaneously - Dense wavelength multiplexing (DWDM) o Used on most modern fiber optic networks o Extraordinary capacity
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Relationships Between Nodes Point-to-point transmission One transmitter and one receiver Point-to-multipoint transmission One transmitter and multiple receivers Broadcast transmission One transmitter and multiple, undefined receivers Used on wired and wireless networks Simple and quick Nonbroadcast One transmitter and multiple, defined recipients Throughput and Bandwidth Throughput Amount of data transmitted during given time period Also called capacity or bandwidth Expressed as bits transmitted per second Bandwidth (strict definition) Difference between highest and lowest frequencies medium can transmit Range of frequencies Measured in hertz (Hz) Baseband and Broadband Baseband transmission Digital signals sent through direct current (DC) pulses applied to wire Requires exclusive use of wire’s capacity Transmit one signal (channel) at a time Example: Ethernet Broadband transmission Signals modulated as radio frequency (RF) analog waves Uses different frequency ranges Does not encode information as digital pulses Transmission Flaws - noise o any undesirable unfluence degrading or distorting signal - types of noise o EMI (electromagnetic inference) Radio requecny interference
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o Cross talk Signal on one wire infringes in adjacent wire signal Near end cross talk (NEXT) occurs near source - attenuation o loss of signals strength as it travels away from source - signal boosting technology o analog signals pass through amplifier noise also amplified - regeneration o digital signals retransmitted in original form o repeater: device regenerating digital signals - amplifiers and repeaters o OSI model physical layer - Latency o Delay between signal transmission and receipt o May cause network transmission errors - Latency causes o Cable length o Intervening connectivity device - Round trip time (RTT) o Time for packet to go from sender to receiver and then back from receiver to sender Common media characteristics* - selecting transmission media o media networking needs with media characteristics - physical media characteristics o throughput o cost o noise immunity o size and scalability o connectors and media converters throughput - most significant factor in choosing transmission method - cause of throughput limitations o laws of physics o noise o signalling and multiplexing techniques o devces connected to transmission medium - fiber optic cables allow faster throughput compared to wireless or copper cost - precise costs difficult to pinpoint
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- media cost dependencies o existing hardware, network size, labour costs -
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  • Fall '12
  • FaridShiraz
  • Twisted pair, shielded twisted pair, data networks, transmission media

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