INTRODUCTION OF BROADBAND COMMUNICATION SYSTEMSCHAPTER 1

BROADBANDIn general, broadband refers to telecommunication in which a wide band of frequencies is available to transmit information. Because a wide band of frequencies is available, information can be multiplexed and sent on many different frequencies or channels within the band concurrently, allowing more information to be transmitted in a given amount of time (much as more lanes on a highway allow more cars to travel on it at the same time). Related terms are wideband (a synonym), baseband (a one-channel band), and narrowband (sometimes meaning just wide enough to carry voice, or simply "not broadband," and sometimes meaning specifically between 50 Kpbs to 64 Kpbs).

BROADBANDBroadband Connections:DSL, Cable, Wireless, Satellite.Broadband refers to advanced communications systems capable of providing high-speed transmission of services over the Internet and other networks.Transmission speeds typically exceed 200,000 bits per second in at least one direction: Downstream:From the Internet to the user's computer.Upstream:From the user's computer to the Internet.

BROADBAND VS BASEBANDBroadband vs. Baseband: Baseband:Only one signal on the wire at once.May use Time Division Multiplexing (TDM)Broadband:Multiple signals on the same line.Frequency Division Multiplexing.

DIALUP (BASEBAND)Dialup Access:Inexpensive using existing telephone lines.The slowest option, it is typically used by mobile workers in areas where high speed connection are not available.

BROADBANDBroadband can be delivered to SOHOs via the following technologies:Satellite WirelessCable/FiberDSL

DSL Technology

DSL is a means of providing high-speed connections over installed copper wires.A typical phone line can handle signals up to 1 MHz.A typical phone conversation uses from 300 Hz to 3 kHz.The additional bandwidth is used for DSL.Digital Subscriber Line (DSL)

What is DSL?DSL uses the high frequency range of up to about 1 MHz. For example, asymmetric digital subscriber line (ADSL) uses the frequency range of about 20 kHz to 1MHz. ADSL does not overlap the plain old telephone service (POTS) voice frequency range. (300 3,400 Hz)POTS and ADSL service can coexist over the same wire. Other DSL variants like single-line digital subscriber line (SDSL) use a frequency range that overlaps the POTS voice frequency range. POTS and SDSL service cannot coexist over the same wire.

Digital Subscriber Line (DSL)DSL Access:DSL also uses telephone lines.A DSL modem separates the DSL signal from the telephone signal.Provides an Ethernet connection to a host computer or LAN.

DSL ImplementationsAsymmetricFaster downstream than upstream transfer rate

SymmetricSame downstream and upstream transfer rates

DSL limitationsThe distance from CO to the DSL CPE must be considered. The longer the distance, the lower the speed. Thicker wire gauge supports higher speed.

ADSL and POTS coexistenceThere is a POTS splitter at the central office (CO) (or at home) to split up the POTS called voice and ADSL called data traffic. The POTS traffic goes to the voice switch in the CO, and the ADSL traffic goes to the DSLAM in the CO. ADSL offloads the data or modem traffic from the voice switch and keeps analog POTS separate from data.

Wireless Introduction

Wireless networking, or Wi-Fi, has improved the connectivity situation, not only in the SOHO, but also on enterprise campuses. Using 802.11 networking standards, data travels using the unlicensed radio spectrum. Most radio and TV transmissions are government regulated and require a license to use. Broadband Wireless

Until recently, a significant limitation of wireless access has been the need to be within the local transmission range (typically less than 100 feet) of a wireless router or wireless access point that has a wired connection to the Internet.Once a worker left the office or home, wireless access was not readily available.New developments in broadband wireless technology are increasing wireless availability.Municipal Wi-FiWiMAXSatellite InternetBroadband Wireless

Municipal Wi-Fi:Most municipal wireless networks use a mesh topology rather than a hub-and-spoke model.The mesh blankets its area with radio signals.Signals travel from access point to access point through this cloud.Installation easier.Faster deployment.More reliable.Broadband Wireless

WiMAX:WiMAX (Worldwide Interoperability for Microwave Access) is telecommunications technology aimed at providing wireless data over long distances in a variety of ways. WiMAX operates at higher speeds, over greater distances, and for a greater number of users than Wi-Fi. Because of its higher speed (bandwidth) and falling component prices, the WiMAX will soon supplant municipal mesh networks for wireless deployments.Broadband Wireless

WiMAX:Broadband WirelessTwo main components

Wireless Bridging

Monthly Leased Line OpEx2 DS1: $6001 DS3: $5000TOTAL: $5600

TMnet provides guaranteed level of service via a Service Level Agreement (SLA)Traditional WAN Connectivity

Wireless Installation Cost7 350 Series Bridges Installed: $12,500 USDPay Back Period: 3 monthsNew building connectedSelf managed802.11b Connectivity

Wireless Installation Cost7 1400 Series Bridges Installed: $40,000 USDPay Back Period: 8 monthsNew building connectedSelf managed802.11a/g Connectivity

Optional 2.4GHz Antennas for Long Range13.5 dBi YagiDistances over 11.7 Km @ 2 Mbps5.8 Km @ 11 Mbps21 dBi Solid DishFor distances up to40+ Km @ 2 Mbps 33 Km @ 11 Mbps

802.11a/b/g/n Bridge Application: UTHMFKEEYagiDSIYagi

Satellites

Satellite Internet:Satellite Internet services are used in locations where land-based Internet access is not available, or for temporary installations that are continually on the move. There are 3 ways to connect to Internet using satellites:One-way multicast are used for IP multicast-based data, audio, and video distribution. One-way terrestrial return use traditional dialup access to send outbound data through a modem and receive downloads from the satellite.Two-way satellite sends data from remote sites via satellite to a hub. The hub then sends the data to the Internet.

Satellite Access:The computer connects to a satellite modem that transmits radio signals to the nearest point of presence within the satellite network.Provides an Ethernet connection to a host computer.

Two-way Satellite Internet:Broadband WirelessThe key installation requirement is for the antenna to have a clear view toward the equator.Two-way satellite Internet uses IP multicasting technology. Allows one satellite to serve up to 5,000 channels.

Satellite options Older deployments from satellite data providers used asymmetric data paths a satellite downstream to the customer, and a dialup modem for the return path to the provider. Today, a transmitter and a receiver are installed for communications.Satellite services deliver data at downstream speeds up to 1,500 kbps, and upstream speeds as high as 125 kbps. Due to the asymmetric nature of satellite communication, certain applications do not perform very well over satellite such as voice.

Satellite SOHOThe typical satellite system requires:small 1.2 m (3.9 ft) satellite dishtwo standard coaxial cables to connect the satellite disk to a satellite modemthe satellite modem that connects to a PC through an Ethernet or USB port. Satellite networks include:geostationary orbit satellites (GSOs) (22,300 miles) Disadvantage of second ground-satellite-ground delaynon-geostationary orbit satellites (NGSOs). NGSOs include low-earth-orbit satellites (LEOs).

Satellite big repeaters in the skytransponders = repeater units carried by the satellite 10 to 46 transponders per satelliteeach transponder can carry up to 3,000 DS-0, (64 kbps) channelsuses radio waves to transmit databandwidth in the Mbps

Satellite Extras

Geosynchronous / Geostationary satellitesorbits earth at an altitude of 22,300 miles above the equatortakes 24 hours to orbit earthappears stationary to the human eye or to the satellite dish

Satellite Extras

Advantageslarge footprint broadcast, send once - receive manycost effective for remote areas3 - 4 satellites can cover the earth

Satellite Extras

Disadvantagespromulgation delay: long delay, .12 seconds for a single hop or .24 seconds (1/4 second) for roundtriplimited orbit space or positions for these satellitesinitially expensive to put in orbitsubject to noise and interferencetwo-way communications expensive (inexpensive: receive only)Satellite Extras

Low Earth Orbit Satellites (LEO)non-stationary satellites of lower orbits which has a smaller promulgation delayhome satellite dishes act more like cellular phones, jumping from satellite to satellite as the satellites move in and out of rangeTeledesic Network (A Microsoft Project): satellites at a low orbit about 435 milesSatellite Extras

An orbiting global constellation of 1,000 small, advanced, semi-autonomous, inter-connected satellites.prevents the signal delays inherent in the use of conventional geostationary communication satellites which operate at a higher altitudeHughes Network Systems DirecPC: 400 kbps and in the future up to 92 MbpsIridium System - uses a central control station, 66 satellites, handheld phones and gateways to the PSTN.Satellite Extras

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