Abstract:
Last mile technology faces challenges to provide efficient infra structure and high speed wide area network protocols in terms of cost and technical implications . There are several technologies (ISDN, Optical fibers, DSL, 2G, 2.5G, 3G, WiMaX) that provide access to small and medium size enterprises .Comparing these technologies to provide service access to enterprises or consumers it can be conclude that WiMax is cost effective ,reliable and can provide access with high speed wide area network access .It also addresses the technical implications faced by small and medium enterprises in terms of infra structure, security and bandwidth.
INTRODUCTION :
The need to have fast and super fast infrastructure to transfer data between two sites by using voice digital and video communication resulted in introduction of many high speed wide area network protocols.this paper discuses
High speed wide area network protocols.
Concepts of last mile technology.
Perspectives of the “last mile Problems”.
Recommendations aimed at fostering broadband's deployment and its use.[1]
Last-mile technology:
Last-mile technology is defined as any type of telecommunications technology, such as wireless radio, that carries signals from the broad telecommunication along the relatively short distance to and from the home or business with efficient band width to access internet and web pages.[2]
Today, in addition to "plain old telephone (dial-up) service", last-mile technologies to deliver voice, data, and TV can include :
1. ISDN(integrated Services Digital Network) – It refers to a collection of standards that define a digital architecture that provides an integration voice/data capability to customer premises facility, utilising the PSTN. ISDN standards define the hard ware and call set up end to end digital connectivity.
When compared to modem (56Kbps) it is very fast at the rate of 128Kbps.
The two levels of services are the BRI(Basic Rate Interface), proposed for the home and small enterprise and PRI(Primary Rate Interface) , for large users. Both rates include a number of B-channels and D-channels. Each B-channel carries data and voice (digital) and D-channel for signalling(digital).
The Basic Rate Interface consists of two 64 kbps(B-channels ) and one 16 kbps (D-channels).Thus, a Basic Rate user can get 128kpbs service. The Primary Rate consists of 23 B-channels and one 64 kbps d-channel in United States of America or 30 B channels and one D-channel in Europe.[2]
2. Digital Subscriber Line over existing telephone twisted pair lines
DSL(Digital Subscriber Line) is a technology for bringing high -Bandwidth information to homes and small business over ordinary copper telephone lines .xDSL refers to different variations of DSL, such as ADSL (Asymmetric DSL)down link band width is high than uplink ,HDSL(High bit –rate DSL)symmetric band width in both directions if it is E1(2.544Mbps)and T1(1.544Mbps)and RADSL(Rate Adaptive DSL)automatically adjusts line speed based on condition of the line and Single line digital subscriber(1.544 Mbps) also know as symmetric digital subscriber line- it does on single set of twisted copper.
Theoretical connection speed: 8.448Mbps
Practical connection speed : 6.1Mbps
Individual connection will provide from 1.544Mbps to 512 kbps downstream and 128 kbps upstream.
A DSL line can carry both data and voice signals and the data part is continuously connected. DSL installations began in 1988 and increased
Gradually through the next decade in a number of communities in the U.S . Compaq , Intel and Microsoft working with telephone companies have developed a standard and make easier process to install D.DSL is expected to replace ISDN in many areas and to complete with the cable modem in bringing multimedia and 3-D to homes and small businesses.[2]
3. Optical fiber technologies
Optical fiber refers to the medium and the technology associated with the transmission of information as light pulses along a glass or plastic wire .
Optical fibre carries much information than conventional copper wire and in general not subjected to electromagnetic interference and the need to retransmit signals. Most telephone company long distance lines are now of optical fibre. Single mode fibers are used for long distance where as multi mode fibers are used for short distance.
These optical cables transmit information at rate of 2Gbps where as in case of twisted cables and coaxial cables transmits information at a rate of 4Mbps and 500 Mbps .optical fibre requires repeaters at a distance of 10-100 km.
Wireless communication services:
Def: The transmission of information signal from source to destination by using radio waves through microwaves antennas or sectorised antennas and
Cordless telephones and cellular telephones.[3]
Cellular phones provides connectivity for portable and mobile application, both personal and business.
Global positioning system(GPS) allows drivers of cars, trucks
Captains of boats and ships, identification of cells in RF survey
And pilots of aircrafts to as certain their location anywhere on earth.
Satellite television allow viewers in almost any location to get live .
Wireless LAN or local area networks provide flexibility and reliability for business computer users.[2]
The potential features of each wireless communication services will be discussed below:
WAN TECHNOLOGIES
Global systems for mobile communication (GSM) : It is a type of time division multiple access(TDMA) digital wireless networks(IS-136 standard) that has encryption features. The frequency used in GSM is 900MHZ (890-915) uplink and (935-960)down link, 1900 MHz(1850-1910)up link and (1930-1990) down link frequency, which gives the speed of 22.8Kbps with redundancy.
GSM (2G)supports only voice.
MAIN FEATURES :
Authentication of subscribers.
Subscriber identity confidentially.
Excellent speech quality
Subscriber identity module.
Radio interface encryption.
Disadvantages:
This 2G technology supports only voice calls, multi path fading is the drawback [4]
GPRS(General Packet Radio Service)- It is a packet –based wireless communication service that provides continues connection to the internet for mobile phones and computer users. This comes under 2.5G technology with reusing the existing GSM infra structure at a speed of 56- 114 kbps. It will support voice and data. new components
Like SGSN (Serving GPRS Support Node)and GGSN(Gate way GPRS Support Node).IP is the back bone network. Some software and hardware up gradation has made in GSM network.This technology is used to access internet with out wire but depending up on the radio resources the user can access internet with a speed 56-114kbps.DHCP ,PCF(packet control function)and CHAP are used for Authentication and security purpose.[5]
Enhanced Data For GSM Evolution(EDGE)-
This technology is the next step in the evolutionof the global systems for mobiles(GSM)and IS-136 wireless service. This technology is to increase data transmission rates 384 Kbps and spectrum effiency and increase the capacity for mobile use. This introduced a new modulation techniques and new channel coding that can be used to transmit packet switched and circuit switched voice and data services.this offer the same service as WCDMA.
Universal mobile telecommunication system(UMTS)-
It is 3G technology with a speed of 2Mbps per mobile and eastablish a global roaming standard. satellite role comes into picture if a user is beyond the city.
UMTS specifications:
Network access security
Network Domain security
User Domain security
Application Domain Security
WiMax is an efficient last mile technology: Analysis
Today broad band has to be locked to a landline connection with T1,DSL or Cable modem. WiMax ( Worldwide Interoperability for Microwave Access) an evolving standard for point-to-multipoint wireless networking, may change that for the last mile in the same way that Wi-Fi has changed the last one hundred feet of networking.
Microwave broadband is actually a very old technology with setting up T-1 (1.54Mbps) microwave connections in the early 80s. Proprietary point to multipoint microwave networks from companies like Alcatel and Siemens have existed for decades. But the technology has also been extremely proprietary and that has limited its popularity. WiMAX brings to the plate is that it's attempting to standardize the technology.
WiMAX may change that not only for rural areas, but for anyplace where the cost of laying or upgrading landlines to broadband capacity is prohibitively expensive.
WiMAX is the commercialization of the maturing IEEE 802.16 standard. In short, "WiMAX is the marketing arm of 802.16." 802.16 is, according to its charter, "a standard, which specifies the WirelessMAN Air Interface for wireless metropolitan area networks." The standard, which was published on April 8, 2002 is meant to "address the 'first-mile/last-mile' connection in wireless metropolitan area networks (MAN)."
IEEE 802.16 was standardized in 2001
IEEE 802.16a and 16c standardized in 2003 for LAN and MAN- Air interface for fixed broad band wireless access system.IEEE802.16.2 standardized for co-existence of broad band wire less access systems.
WiMAX (Worldwide Interoperability for Microwave Access) is the IEEE 802.16 standards based wireless technology that provides MAN (Metro politician Area) Broad band connectivity.
It is an improved technology of WiFi (LAN) in performance and usage over much greater distances(max 30miles).The original WiMAX standard,
IEEE 802.16, specifies WiMAX in the 10 to 66 GHz range. 802.16a
added support for the 2 to 11 GHz range.The WiMAX specification improves upon many of the limitations of the Wi-Fi standard by providing increased bandwidth and stronger encryption.
Practically this technology gives maximum data rates between 500kbit/s and 2 Mbit/s, depending on conditions at a given site... [6]
http://www.flarion.com/images/products/diagram_products_intro_1.jpg
Protocols used in WiMAX:
802.16 MAC protocol- used for prioritization of traffic based on first in first out and this protocol ensures the quality of service (QOS)
802.16a- used for encryption of radio signals (phase shift keying, WEP and WPA)
X.509- in Base station to validate the user before permitting to the physical layer
802.16c- Interoperability, with protocols and test-suite structures
802.16e- support for mobile as as well as fixed broadband.
These protocols solves the problems in last mile technologies. [7]
IEEE 802.16 is a latest entry into in this wireless networking technology which is an alternative to DSL, cable connection, cable modem, leased lines and other broadband technologies.
This will enable data center consolidation, cost saving and allow us to deploy a broadband mesh connectivity all our sites in a region.
This standard which is made up of silicon product have a range of up to 30miles and has the ability to transfer data,voice,signalling and video at a speed up to 60-70Mbps.
Connecting the Last mile connection network to a wide area network provider:
A wide area network(WAN) is a geographically dispersed telecommunications network. The term distinguishes a broader telecommunication structure from a local area network (LAN). A wide area network may be privately owned or rented, but the term usually connotes the inclusion of public (shared user) networks. An intermediate form of network in terms of geography is a metropolitan area network (MAN).
There are so many ways to connect to the wide area network provider
1)Point to Point Wireless Wide Area Network(WWAN)
Last mile access where fiber cant reach
Supports all Ethernet protocols
Supports voice, data and video applications
2) Point to Multi- point Wireless Wide Area Network(WWAN)
Supports all Ethernet protocols.
MAC layer bridge with IP routing option.[8]
Cost Analysis:
According to this analysis ,wireless technology (WiMax) will grow beyond our expectations by 2010($1 billon).the cost to install wimax plat form for small and medium sized enterprises will cost about $500 -$750, much less than normal T1 services.
Conclusion :
Reliability and security of a network ensures that all its customers internal or external will be able to access the network without any difficulty in terms of preferred location and time. The features and options required for the network can be estimated by analyzing the cost of reliability and down time of the network.References and appendices to your section:
[1]www.nap.edu/broadband brining home the bits, national economy of science, p. p- 10-25 ,accessed on oct 25 2005
[2]http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212399,00.html accessed on oct 25th 2005
[3]http://www.google.co.uk/url?sa=X&start=1&oi=define&q=http://www.fortfrancesbroadband.ca/terms.htm
[4] M.Mouly and M.B pautet, The GSM system for mobile communication, palaiseau,1992.
[5] S.bucking ham, Data on GPRS, Mobile life streams Limited,1999.and ETSI,GSM 03.60,2.06 Digital cellular telecommunication systems (phase2+);
General packet radio service,service description stage 2.
[6]http://en.wikipedia.org/wiki/Wimax
[7]rfdesign.com/mag/radio_security_considerations_wimaxbased/index.html
[8]http://www.enterpriseitplanet.com/networking/features/article.php/3348111
