Broad Band Networks
CHAPTER-1
Introduction
1.1 Setting the Stage
Broadband, the darling of techno-sophisticates and an object of interest to a growing number of politicians and government officials, as well as to the general public, is often misunderstood.
The term itself, originating in the characterization of a communications channel’s capacity (in contrast to narrowband), has come to be used as, among other things, a marketer’s label for advanced cable television service, the 21st-century incarnation of the early 1990s “information superhighway,” and one element of the next stage in the development of the Internet.
Broadband has been a beacon for investors and a stimulus for entrepreneurs and mainstream businesses, and it has intensified debates about the public interest in information and communications infrastructure.
CHAPTER-2
Broadband
Architecture
2.1 Broadband
· In general refers to data transmission where multiple pieces of data are sent simultaneously to increase the effective rate of transmission.
· Network capable of transporting voice, image, and video and data signals at a rate of more than 1.5 million bits of information per second.
2.2 Why Broadband?
Broadband is the always-open gateway
to a new world of Internet-based services delivered at lightning-fast speeds to
households and businesses. Broadband in general refers to data transmission
where multiple pieces of data are sent simultaneously to increase the effective
rate of transmission. In network engineering this term is used for methods
where two or more signals share a medium.
Various forms of Digital Subscriber
line service are broadband in the sense that digital information is sent over
one channel and voice over another channel sharing a single pair of wires.
Wireless internet is over cellular towers. Analog modems
operating at speeds greater than 600 bit/s are technically broadband. They
obtain higher effective transmission rates by using multiple channels with the
rate on each channel limited to 600 baud. For example, a 2400 bit/s modem uses
four 600 baud channels.This is in contrast to a baseband transmission where one
type of signal uses a medium's full bandwidth such as 100 Base T Ethernet..
2.3 Multiplexing
Communications may utilise a number
of distinct physical channels simultaneously; this is multiplexing
for multiple access. Such channels may be distinguished by being separated from
each other in time (time division multiplexing or TDMA), in carrier
frequency (frequency division multiplexing
(FDMA) or wavelength division multiplexing
(WDM)), or in access method (code division multiplexing or CDMA). Each channel that
takes part in such a multiplexing exercise is by definition narrowband (because
it is not utilising the whole bandwidth of the medium), whereas the whole set
of channels taken together and utilised for the same communication could be
described as broadband.
2.4 Confusing usage
While many lower rate forms of data
transmission, such as analog modems above 600 bit/s, are broadband, broadband
has been more closely associated with higher data rate forms of broadband data
transmission such as T-carrier and Digital Subscriber Lines.
Therefore, the word
"broadband" has also come to mean a relatively high rate, while the
term "narrowband" is used to mean a relatively low rate. It is now
quite common to hear a broadband method such as a 9600 bit/s modem described as
"narrowband", while a high rate baseband transmission such as 10BASE-T
is described as "broadband".
The International Telecommunication Union
Standardization Sector (ITU-T) recommendation I.113 has defined broadband as a
transmission capacity that is faster than primary rate ISDN, at 1.5 to 2 Mbit/s.
However speeds of 256 kbit/s and greater are commonly marketed as
"broadband" and this convention is held to by policy makers and ISPs
alike. See Broadband Internet access. Note: The term
"narrowband"
is also used to mean the opposite of "wideband"
instead of the opposite of "broadband".
·
In
effect, broadband is a huge digital pipeline that links consumers to the
Internet's deepening pool of news, information, entertainment and data.
CHAPTER-3
BROADBAND ENDPOINTS
3.1 Different technologies
· Blue tooth à Palmtops
· Wireless à Handset, laptops
· Ethernet à PC in LAN
·
USB
à Digital
· Other à Home theatre system, Refrigerator, Oven, Alarms, etc
· Integration of such independent technologies makes Broad band so very special.
3.2 Level of Abstraction?
· Application specific infrastructure is provided independently.
· All the devices are made accessible with full functionality.
· Protocols applicable are relative to respective technologies.
3.3 Software Evolution
·
Provided such an extensive combination of
devices & technologies has tempted software developers to tap this
opportunity & provide customers worldwide access systems on very
competitive prices.
3.4
Characteristics- Broadband network
OVERVIEW OF THE
TECHNICAL CHARACTERISTICS OF BROADBAND
Communications capacity, or speed, is only one of a set of performance characteristics of a service.
That it is not the whole picture is easily seen in the contrast between dial-up access, where the modem must place a telephone call and negotiate a connection with the ISP’s modem, and the services available today that are generally considered broadband—which frequently offer “always-on” connectivity as well as high speed. Along with speed and always on are additional parameters such as bandwidth symmetry and address ability that are important components of a definition of broadband.
Each of these is considered in the sections that follow.
· Speed
The speed or bandwidth of a service—the rate at which one can transfer data to and/or from the home—is a function of multiple factors. Because the effective bandwidth reflects the capacity of the end-to-end connection between sender and receiver, the speed seen by a user can be constrained at any one of a number of points between the user’s computer and the computer providing a particular service.
However, speeds within the core network have been rising, at least in the United States and other developed nations, and the capacity of the network link between the user and the broadband provider’s network is one of the crucial factors that determines how the broadband service can be used.
The better-than-dial-up criterion for broadband assures that a service is at least a little better than what was available before, but it does not address the question of whether the service is good enough. And while a 2- or 5-Mbps threshold would seem ample for most applications envisioned today, it might, on the one hand, prove inadequate in the future, or, on the other, raise questions about whether its costs today would exceed what customers are willing to pay for today.
As indicated earlier, the effective speed for interacting with an Internet host is not merely a function of the performance of the broadband local access link—it depends on the entire path between the host and the user, and also on the loading on the host computer. As a result, depending on the circumstances, improvements in the performance of one link does not necessarily improve overall performance—it may only shift the bottle- neck. Network infrastructure such as caching and content hosting within the local ISP access networks also has a substantial effect on perceived performance to the end user and loading on the connections to the core Internet.
Where are the bottlenecks, and how might they shift as broadband access technologies are upgraded? Today, for dial-up users interacting with most commercial hosts, the bottleneck is the last mile dial-up connection. With the current generation of deployed broadband—cable modems, DSL, or wireless services—the location of the typical bottleneck, at least for routine Web access, is less clear. It may be in the last mile, within the local ISP network, at the upstream linkage between the cable-modem or DSL ISP and the Internet core, closer to the host, or even in the user’s PC.
The link to core Internet service providers is typically going to be paid for on a leased basis, and its costs rise as the bandwidth of the link increases. In contrast, high local bandwidth within the community incurs mainly the fixed capital costs of installing and lighting the fiber network (which can be financed for a long period of time). Thus, where very fast FTTH networks are deployed, they can have the property that access to hosts within the community served is very fast, but that more general access to Internet sites is much slower; it may thus be possible to exchange high-definition video with a neighbor or a local community center, but difficult in the short term to extend this level of performance beyond a modest geographical region.
· Latency and Jitter
While the net throughput is the most significant enabler of many applications, two additional parameters are crucial for applications that depend on real-time delivery of information or interaction, such as telephone or interactive game playing. “Latency,” or delay, is a measure of how long it takes to deliver a packet across the network to its destination.
Latency is a function of the distance the packet travels (speed of light, which is of particular significance for traffic carried over geosynchronous satellites), the length of time the packet waits in queues within the network, and the delay that results from retransmission when a packet is dropped due to congestion within the network. Latency especially affects applications that depend on interaction, such as human-to-human conversations, games, and the like. “Jitter” measures the variation in latency, resulting from such factors as variations in the path taken by each packet, variable queue lengths, or variations in the level of congestion within the network. Even if the average latency is acceptable, high jitter may make the application unusable nonetheless.
· Symmetry Between
Upstream and Downstream Capacity
Today, telecommunications services, including broadband, do not necessarily provide the same capacity up- and downstream. At one extreme, digital cable television service and direct broadcast satellite service provide a very high data rate digital connection into the home.
These services may also provide a low data rate return path—over the same link or over an alternative return link using a phone line—to enable enhanced services such as pay-per-view. However, most users probably would not think of these services as broadband—they expect broadband to include high-speed Internet access (perhaps along with these predominantly one-way services). On the other hand, broadband does not necessarily imply that one must have anything close to symmetric bandwidth to and from the premises—though some would argue that it will, over time, as a consequence of the minimum bandwidth particular applications require.
The asymmetric services typically found in today’s residential broadband services were designed with one of two asymmetrical application classes in mind. One class is Web browsing, where a low-bandwidth upstream connection serves to carry a user’s requests for Web pages, and the higher downstream connection returns the content the user has requested; e-commerce or other applications in which users interact via entering information in Web forms involve a similarly asymmetric communications model. The other class, audio or video delivery, in which a small amount of data is sent upstream to select and direct delivery of a particular stream (delivery of packets for playback in near-real time), is even more asymmetric.
CHAPTER-4
PREMISE ACCESS GATEWAY
4.1 What is a Gateway?
· Gateway is an Interface that permits access to Wide area networks.
· Any PC having access to Internet has to be serviced by minimum of one gateway.
· Gateways in turn are dependable or serviceable by Internet Service Providers.
4.2 Different ways to log
into the world of Broadband network
· Via Ethernet cable.
· Via Wireless technologies
· Via Leased line
·
Via Cable modem
·
All the above techniques provide access to
consumer end the backbone services which are always of very high data rate.
·
The First Mile logic.
· The Last Mile logic..
o Premise
gateway registers itself onto infrastructure gateway to access the data
worldwide.
o The
latter provides final link point to the world of Internet.
· Hardware & Software platforms
o Almost everything is DSP processed, as it increases the very much needed speed computation.
o Software includes processing of multimedia services
o Ex:
MM7 gateway.
o Physical
cable plugging is done.
·
Different categories of OFC
o OC – 3
o OC – 4
o OC – 198
o DS – 3
CHAPTER-5
Future
Aspects
- Creating an integrated national tax service system for online payments and Notifications
- Providing
an online portal of customs services including an internet-based Customs clearance system
- Digitizing
the justice and law enforcement system for increased public safety and
linkage between various organizations that are involved in the process
countrywide
- Instantaneous video conferencing services
- Interactive TV that lets viewers change camera angles and play along with game- show contestants
- 3-dimensional games that let players engage with people across the street, as well as on the other side of the world.
- Shift from PC world to Embedded world
- Interoperability – Multi vendor solutions in real world environments
- Combinable: Cellular, Blue Tooth, VoIP
CHAPTER-6
APPLICATIONS
·
Mobile
VoIP.
·
IP Video
Phones.
o Combination of low – cost bandwidth and powerful low cost processor make a rich video experience possible for the first time.
o Video connectivity with telephony ease of use.
·
Promise
& Reality
o Fast file downloading
o Live Gaming
o Network storage
o Static image delivery
o Playback of music
o Application rental
o Software updates
·
Video
based applications
o Network camera
o Media to Go
o Video on demand
o IP video phone
o Video surveillance
o DVD player
o Broadcast equipments
CHAPTER-7
CONCLUSION
· Strong Growth in broadband exists today fueled by consumer demand for Broadcast content and services
· Broadband access is evolving from high speed always on Internet to the connected home.
- Broadband is viewed by some as a double-edged sword: networking could promote economic development, yet electronic commerce also has the potential to displace local businesses.
· Broadband is changing the way we live, work and play.
· Broadband entry shall bring more communications and shall increase manpower usage.
· Imagination can be tapped onto reality as The power of Internet shall enable youth to or rather encourage them to learn, do research apply creativity skills onto their subjects of interests.
· Broadband is a boon to the knowledge economy like ours.
· Geographical reachable complications can easily be minimized to greater extent.
Challenges
· Improved Security to protect Consumer, Provider & Content
· New evolving standards
· Demand for high-speed connections, Streaming video and audio
· Compression will have less importance in contrast with Quality
· More Bandwidth consumed per home
· QoS Needed End-to-End
· Network capable consumer electronic devices
REFERENCES
· Computer Communication Networks – Andrew S. Tennenbaum
· www.m-indiya.com
· www.semenarsonly.com
· www.howstuffworks.com
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