Broadband Telecommunication

Broadband

In telecommunications, broadband is a wide bandwidth data transmission with an ability to simultaneously transport multiple signals and traffic types. The medium can be coaxial cable, optical fiber, twisted pair, or wireless broadband (wireless broadband includes Mobile broadband). In contrast,baseband describes a communication system in which information is transported across a single channel.

In telecommunications, a broadband signaling method is one that handles a wide band of frequencies. "Broadband" is a relative term, understood according to its context. The wider (or broader) the bandwidth of a channel, the greater the information-carrying capacity, given the same channel quality. Broadband telecommunication is completed by the help of ATM, ISDN, Frame Relay, etc.

ATM

Asynchronous Transfer Mode (ATM) is, according to the ATM Forum, "a telecommunications concept defined by ANSI and ITU (formerly CCITT) standards for carriage of a complete range of user traffic, including voice, data, and video signals". ATM was developed to meet the needs of the Broadband Integrated Services Digital Network, as defined in the late 1980s, and designed to unify telecommunication and computer networks. It was designed for a network that must handle both traditional high-throughput data traffic (e.g., file transfers), and real-time, low-latency content such as voice and video. The reference model for ATM approximately maps to the three lowest layers of the ISO-OSI reference model: network layer, data link layer, and physical layer. ATM is a core protocol used over the SONET/SDH backbone of the public switched telephone network (PSTN) and Integrated Services Digital Network (ISDN), but its use is declining in favour of all IP.

ISDN

Integrated Services for Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. Prior to ISDN, the telephone system was viewed as a way to transport voice, with some special services available for data. The key feature of ISDN is that it integrates speech and data on the same lines, adding features that were not available in the classic telephone system.

Integrated services refers to ISDN's ability to deliver at minimum two simultaneous connections, in any combination of data, voice, video, and fax, over a single line. Multiple devices can be attached to the line, and used as needed. That means an ISDN line can take care of most people's complete communications needs (apart from broadband Internet access and entertainment television) at a much higher transmission rate, without forcing the purchase of multiple analog phone lines. It also refers to integrated switching and transmission in thattelephone switching and carrier wave transmission are integrated rather than separate as in earlier technology.

Frame Relay

Frame relay is a standardized wide area network technology that specifies the physical and logical link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces.

Network providers commonly implement frame relay for voice (VoFR) and data as an encapsulation technique, used betweenlocal area networks (LANs) over a wide area network (WAN). Each end-user gets a private line (or leased line) to a frame relaynode. The frame relay network handles the transmission over a frequently changing path transparent to all end-user extensively used WAN protocols. It is less expensive than leased lines and that is one reason for its popularity. The extreme simplicity of configuring user equipment in a frame relay network offers another reason for frame relay's popularity.

Difference between ATM and Frame Relay

1. Although both techniques are based on end to end delivery of quantized data, there are many differences in terms of sizes of the data quanta, application network types, controlling techniques etc.

2. Although ATM uses fixed size packets (53 bytes) for data communication, frame relay uses variable packet sizes depending on the type of information to be sent. Both information blocks have a header in addition to data block and transfer is connection oriented.

3. Frame Relay is used to connect Local Area Networks (LAN) and it is not implemented within a single area network contrast to ATM where data transfers are within a single LAN.

4. ATM is designed to be convenient for hardware implementation and therefore, cost is higher compared to frame relay, which is software controlled. Therefore frame relay is less expensive and upgrading is easier.

5. Frame relay has a variable packet size. Therefore it gives low overhead within the packet which results it an efficient method for transmitting data. Although fixed packet size in ATM, can be useful for handling video and image traffic at high speeds, it leaves a lot of overhead within the packet, particularly in short transactions.