Modem Technologies ADSL Modem

Outline of the Presentation Modem Technologies. DSL ADSL Modem Upstream/Downstream Bands and Frequency Bandwidth notation Setup Properties of ADSL Modem Routing and Security Wireless ADSL Cable Modem Comparison of ADSL and Cable Modem

What does modem mean? The word "modem" comes from "modulator-demodulator“ Modulation: digital information to analog signals Demodulation: analog signals back into useful digital information Settled device for computers. Allows 2 computers to communicate over standard phone lines. They have many different shapes and sizes to correspond all kind of needs.

Conversion of Digital Information to Analog Information

What is DSL? Digital Subscriber Line. New modem technology. Data transmission is based on digital encoding (digital). Uses phone line so for the customer wiring (subscribers’ line). Use digital coding techniques to provide more capacity. Allows high-speed Internet access over existing twisted-pair and ordinary copper telephone wires.

What is DSL? Provides "always-on" connection. To transport high-bandwidth data. A special hardware attached to both the user and switch ends of line.

Advantages of DSL High-speed. Secure connection. No dial-up, waiting or dropped connections. It's always on connection. Saves both money and time. Provides large file transfers. Multiple workers on a network can connect to a single DSL.

What is ADSL? Asymmetric Digital Subscriber Line. Is a form of DSL. A high-speed Internet access service. Speed depends on the length and the diameter of the cable and the type of the mode Requires a special ADSL modem and an Internet service provider (ISP) .

What is ADSL? It is asymmetric since the data coming to your computer from the Internet (download) is faster than the data traveling from your computer to the Internet (upload). Uses standard telephone lines. Telephone can be used normally, even when surfing in the Web with ADSL service. An "always on" service. Not available to everyone.

How does ADSL work? ADSL Splitter separates the analogue voice (phone) traffic from data (adsl) traffic. ADSL Modem converts digital signals from your PC into analog signals that can be transmitted over telephone cable in the local loop. Local Loop is the path your telephone line will take from your house to the local exchange. Service Provider. The cable consists of a "copper pair" .

How does ADSL work?

How does ADSL work?

How does ADSL work? •DSLAM - DSL Access Multiplexer •BRAS – Broadband Remote Access Server •ISP - Internet Service Provider

How does ADSL work? The DSLAM associates a number of ADSL user connections as many as several hundred into a single fiber connection. This fiber will normally be connected to a Broadband Remote Access Server or BRAS.

How does ADSL work? BRAS routes traffic to and from the digital subscriber line access multiplexers (DSLAM) on an Internet service provider’s (ISP) network. A single BRAS will probably handle connections from several DSLAMs.

How does ADSL work? This is the place where your connection to the Internet is made. The ISP usually provides other services like mail and news servers, and frequently-used pages from the Internet so that you can access them more quickly.

How does ADSL work?

ISP Internet Service Provider

ISP A company. Access to the internet. Monthly fee. Software package. User name, password and access phone number. Modem. Log-on.

ISP Individuals and large companies. Connected to one another through Network Access Points (NAPs). Examples: Superonline E-kolay. Atlas On-Line. Tr-Net.

ADVANTAGES of ADSL Quick connection. Fast. Use phone connection when connected to the internet. No need for second phone line. No dropped connections. Always on connection. Ability to download large files. Save time. Cost efficiency.

Upstream/Downstream Bands and Frequency ADSL Communication is Full Duplex. Full duplex ADSL communication is usually providing with a wire pair by either frequency division multiplex (FDM). FDM uses two separate frequency bands, these are the upstream and downstream bands.

Upstream/Downstream Bands and Frequency Downstream data. Upstream data. ADSL transmit upstream and downstream data on a digital frequency

Upstream/Downstream Bands and Frequency PSTN (Plain Old Telephone Service ) UPSTREAM DOWNSTREAM Frequency plan for ADSL. The red area is the frequency range used by normal voice telephony (PSTN), the green (upstream) and blue (downstream) areas are used for ADSL.

BANWIDTH NOTATION Monthly quota of data. Upload/download. Monthly bandwidth allowance will be measured in Megabytes or Gigabytes. The amount of bandwidth you need depends on how frequently use the internet.

SETUP PROPERTIES of ADSL Physical connections. Modem synchronization. Computer network configurations. Modem Configuration. Ip Control. Connection Control

ROUTING and SECURITY ROUTING Device. A router allows you to connect one or more computers or one or more networks onto the ADSL service. Many routers have built in switches that allow you to plug your computer directly into them Sharing an Internet connection.

ROUTING and SECURITY SECURITY Change the user name and password after first configuration. Change the port which is used for access to modem settings. Activate the firewall applications. Use Ethernet+Router+USB Adsl modems. Do not use USB Adsl modems. Use antivirus software programs. Update the antivirus programs.

WIRELESS ADSL Without any cable it provides broadband data transfer. This service using at hotspots such as airports, hotels, shopping centers, universities, conference halls etc. If you have WLAN technology in your laptop, phone or etc. You can use this service. If you don not have this technology in your pc you can take a card that has the wi-fi (wireless fidelity ) capability and fix it to your pc than you can use this service. Uses access point which is a wireless access device to spread the adsl connections.

VDSL Very high bit-rate Digital Line Subscriber. Next generation DSL. Entire home-entertainment package . Very high bandwidth. Shorter distance, faster connection. Coding based on Discrete Multitone (DMT) and Quadature Amplitude Modulation (QAM). Is not literally deployed yet

CABLE MODEM CMTS: Cable Modem Termination System CATV: Community Antenna Television or Cable TV system. Can be all coaxial or HFC (Hybrid Fiber Coax) based.

CABLE MODEM Provides high-speed Internet access through a cable television network. TV cables provide much higher bandwidth. Upstream/downstream. Asymmetric. Coaxial cable line. It can be external devices nearly computer or integrated within a computer . “Always on” connection.

ADSL vs CABLE MODEM Speed. Availability. Bandwidth. Time for getting the service. Installation. Service. Cost. Hardware requirements. Security.

WAP/GPRS WAP (Wireless Application Protocol ). Allows users to access information instantly with handheld wireless devices. Internet content in special text format. Low-bandwidth. Uses WML format for small screens and one-hand navigation without a keyboard .

GPRS GPRS (General Packet Radio Service). Uses existing GSM network. Transmit and receive data from GPRS mobile devices. Runs at speeds up to 115 kilobits per second. Supports a wide range of bandwidths. Efficient use of limited bandwidth. Provides “always online” connection.

GPRS

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