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  1. 1. A PRACTICAL TRAINING SEMINAR REPORT ON BHARAT SANCHAR NIGAM LIMITED SESSION 2008-2012 Submitted for the partial fulfillment for the award of the degree of BACHELOR OF TECHNOLOGY OF RAJASTHAN TECHNICAL UNIVERSITY, KOTA SUBMITTED BY: RAJAN MEENA 08EC071 VII SEM (ECE) FINAL YEAR ------------------------------------------------------------------------------ Department of Electronics & Communication Engineering ENGINEERING COLLEGE AJMER (An Autonomous Institute of Govt. of Rajasthan) Badliya Chouraha,N.H. 8,By-Pass,Ajmer-305002 Website : www.ecajmer.ac.in ,Ph no. 0145-2671773,776,800,801 1
  2. 2. ACKNOWLEDGEMENT It is with profound gratitude that I express my deep indebtedness to all the employees of B.S.N.L. without whose support and guidance it would not have been possible for this training to have materialized and taken a concrete shape. I owe my personal thanks to my trainers in charge – Dr. S.l. verma (SDE), and Dr. Sandeep saini (JTO) who extended full support and co-operation at every stage of my training period. I would also like to take this opportunity to acknowledge the guidance from Mr. Dhirender mathur (HOD of electronics and communication) and Mrs. Rekha mehra (Seminar Co-ordinator of electronics and communication) for undergoing training at a reputed company like B.S.N.L. I am also indebted to my parents and friends for their constant encouragement and helping me in my endeavor.Last, but not the least, I would like to thank everyone who has contributed for the successful completion of my training. RAJAN MEENA 08EC071 (B.TECH VII SEMESTER - ECE) 2
  3. 3. PREFACE Organizations are made up of people and function through people. Without people, organizations cannot exist. The resources of men, money, material, machinery, and mechanism are connected, coordinated and utilized through people. Engineers need to concentrate more on mechanism and the way in which things have been made. The need of training arises for doing things yourself, understanding its way. Practical exposure for doing things makes a person conversant to the technicalities involved in any job. In view of such benefits, imparting of vocational training has been made an integral part of any academic structure. In B.S.N.L., training is given to Engineering Aspirants to secure future in the dynamic world of telecommunications. Today telecommunication industry is one of the very fastest growing industries in the world. In this order I have taken 28 days BSNL training. In my report I try to introduce Leased line concepts, WIMAX, Wi-Fi, optical fiber concepts and overview of Intranet. 3
  5. 5. 5 CHAPTER NO. CONTENTS PAGE NO. Cover Page 1 Acknowledgement Preface 3 Contents v-vi List of Figures Vii List of Tables Viii Chapter-1 Introduction to BSNL 1-2 1.1 How BSNL Came to Telecom Network 1 1.2 Institutional Framework 1 1.3 BSNL Contribution to DOT 2 Chapter-2 Working of Basic Telecom network 3-5 2.1 Call Setup 3 2.2 Electronic Exchange 4 2.3 Carrier Room 4 2.3.1 CLLS 4 2.3.2 MLLN 4 2.4 Main Distribution Frame 4 2.4.1 Functions of MDF 5 2.5 Power Plant 5 Chapter-3 Leased Lines 6-7 3.1 Introduction 6 3.2 Drawbacks of LL 6 3.3 MLLN 6 3.3.1 MLLN Features 6 3.3.2 MLLN Advantages 7 3.3.3 Applications Of MLLN 7 Chapter-4 Intranet 8-10 4.1 Introduction 8 4.2 Features of Intranet 8 4.3 Why Intranet for an Organization? 8 4.4 Application of Intranet 9 4.5 Overview of Intranet 9 4.6 Intranet Application in a Circle 10 Chapter-5 Corporate Network 11-12 5.1 Introduction 11 5.2 Why do Organization have CN? 11 5.3 Features of CN Security 12 Chapter-6 WI-FI 13-14 6.1 WI-FI Network 13 6.2 Working of WI-FI Network 13 6.3 Benefits of WI-FI 14 6.4 Limitations of WI-FI 14 Chapter-7 WIMAX 15-18 7.1 Wireless Broadband Services 15 7.2 Salient Features of WIMAX 15 7.3 Evolution of Broadband Services 16 Chapter-8 GSM 19-21 8.1 Features of GSM 19 8.2 GSM Subsystem 19 8.2.1 Radio Subsystem 19 8.2.2 Network and Switching Subsystem 20
  6. 6. LIST OF FIGURES FIGURE NO. TITLE OF FIGURE PAGE NO. FIG 2.1 How Line Reaches From Subscriber To Exchange 3 FIG 2.2 MDF 4 FIG 4.1 Intranet Network 9 FIG 5.1 Corporate Network 12 FIG 6.1 WI-FI Network 13 FIG 7.1 WIMAX Network Architecture 17 FIG 8.1 Basic GSM Network 19 FIG 11.1 Optical Fibre Transmission 24 FIG 11.2 Propagation of Light Through Fibre 25 LIST OF TABLES TABLE NO. TABLE NAME PAGE NO. TABLE 5.1 Difference Between Traditional and Ideal Network 11 TABLE 7.1 Reference Points 18 6
  7. 7. 7
  8. 8. CHAPTER-1 INTRODUCTION TO BSNL India is the fourth largest telecom market in Asia after China, Japan and South Korea. The Indian telecom network is the eighth largest in the world. TYPE: COMMUNICATION SERVICE PROVIDER COUNTRY: INDIA AVAILABLITY: NATIONAL EXCEPT DELHI & MUMBAI OWNER: THE GOVERNMENT OF INDIA WEBSITE: www.bsnl.co.in 1.1 HOW BSNL CAME IN TELECOM MARKET: The initial phase of telecom reforms began in 1984 with the creation of Center for Department of Telematics (C-DOT) for developing indigenous technologies and private manufacturing of customer premise equipment. Soon after, the Mahanagar Telephone Nigam Limited (MTNL) and Videsh Sanchar Nigam Limited (VSNL) were set up in 1986.The Telecom Commission was established in 1989. A crucial aspect of the institutional reform of the Indian telecom sector was setting up of an independent regulatory body in 1997 – the Telecom Regulatory Authority of India (TRAI), to assure investors that the sector would be regulated in a balanced and fair manner. In 2000, DoT corporatized its services wing and created Bharat Sanchar Nigam Limited. 1.2 INSTITUTIONAL FRAMEWORK: It is defined as the system of formal laws, regulations, and procedures, and informal conventions, customs, and norms, that broaden, mold, and restrain socio-economic activity and behavior. The country has been divided into units called Circles, Metro Districts, Secondary Switching Areas (SSA), Long Distance Charging Area (LDCA) and Short Distance Charging Area (SDCA). In India, DoT is the nodal agency for taking care of telecom sector on behalf of government. Its basic functions are: • Policy Formulation • Review of performance • Licensing • Wireless spectrum management • Administrative monitoring of PSUs • Research & Development • Standardization/Validation of Equipment 8
  9. 9. 1.3 BSNL CONTRIBUTION TO DEVELOPMENT OF TELECOM: Bharat Sanchar Nigam Limited was formed in year 2000 and took over the service providers role from DOT. BSNL’s roadmap for providing customer with access to the latest telecommunications services without losing sight of universal service access has been by way of utilizing optimally the existing infrastructure and accelerating advances in technological component by innovative absorption. ACHIEVEMENTS OF BSNL: • BSNL has a customer base of over 9 crore and is the fourth largest integrated telecom operator in the country. • BSNL is the market leader in Broadband, landline and national transmission network. • BSNL is also the only operator covering over 5 lakh village with telecom connectivity. • Area of operation of BSNL is all India except Delhi & Mumbai. 9
  10. 10. CHAPTER-2 WORKING OF BASIC TELECOMMUNICATION NETWORK This section includes brief introduction of how a call is processed when we dial a call from basic telephone to another basic telephone or from basic to mobile or vice versa. 2.1 CALL SETUP: • When a subscriber calls to another subscriber first its request goes to the nearest switching centre that is PSTN (Public Switching Telecommunication Network). Then it processes the caller and subscriber’s number if it exists in the same BSC then call setup is completed. • If subscriber is not in the same BSC (Base Switching Centre) then call transfer to MSC (Main Switching Centre) then it transfers the call to prior BSC then call setup is completed. • If Caller calls to a mobile subscriber then call transfer is done by MTSO now call transfer is done on BTSs (Base Transceiver Station) and call setup is completed. FIG 2.1 HOW LINE REACHES FROM SUBSCRIBER TO EXCHANGE (REF- 1) FUNCTION OF EXCHANGE: • Exchange of information with subscriber lines with other exchange. This is done by two type of signaling: 1. Inchannel signaling 2. Common channel signaling • Processing of signaling information and controlling the operation of signaling network. • Charging and billing. 10
  11. 11. 2.2 ELECTRONIC EXCHANGE: • All control functions by series of instructions are stored in memory. • Memories are modifiable and control program can always be rewritten. For each call processing step decision is taken according to class of service. 2.3 CARRIER ROOM: Leased line connectivity is provided in carrier room. This room has two parts: 1. Conventional leased line system 2. MLLN 2.3.1 CONVENTIONAL LEASED LINE SYSTEM: • It consists of modems and routers that are provided by the company requesting for that network. • Connectivity of different ATM, banks etc. is provided by BSNL here. • For this, we have 4 modems (2 in Exchange, 1 at sender and 1 at receiver) • Modems are used for short distances i.e. trans and receive part are received here and local lead connection is given to the subscriber. • Local lead faults can be handled here but the trans and receive faults can be handled by the department meant for it. • Accept 64Kbps or 2 Mbps. • For long distance communication we have MUXS and data is sent through optical fibers. MUXS are present at both the ends. 2.3.2 MANAGED LEASED LINE NETWORK: • No open wiring. • Route can be changed by the computer software • In Agra Gate Exchange, we have 3 VMUX of type II. 2.4 MDF(MAIN DISTRIBUTION FRAME): M.D.F. is a media between switching network and subscriber’s line. It is a termination point within the local telephone exchange where exchange equipment and terminations of local loops are connected by jumper wires. FIG 2.2 MDF 11
  12. 12. (REF- 4) 12
  13. 13. 2.4.1 FUNCTIONS OF MDF: • All cable copper wires supplying services through user telephone lines are terminated and distributed through MDF. • The most common kind of large MDF is a long steel rack accessible from both sides. Each jumper is a twisted wire. • It consists of local connection and broadband connection frames for the main Exchange area. • The MDF usually holds central office protective devices including heat coils and functions as a test point between a line and the office. • It provides testing of calls. • It checks whether fault is indoor or external. • All lines terminate individually. 2.5 POWER PLANT: • It provides -48V to the switch rooms and 48V to the connections. • Batteries are artificially discharged once in a year for their maintenance. • Cooling is provided through fans & AC. • There is earth region too for protection. 13
  14. 14. CHAPTER-3 LEASED LINES 3.1 INTRODUCTION: A leased line (dedicated line) is a permanent fiber optic or telephone connection between two points set up by a telecommunications carrier. They can be used for telephone, data, or Internet services. Businesses use a leased line to connect to geographically distant offices because it guarantees bandwidth for network traffic. For example, a bank may use a leased line in order to easily transfer financial information from one office to another. Customers generally pay a flat monthly rate for the service depending on the distance between the two points. Leased lines do not have telephone numbers. The information sent through the leased line travels along dedicated secure channels, eliminating the congestion that occurs in shared networks. 3.2 DRAWBACKS OF TRADITIONAL LEASED LINE CIRCUITS: 1. Limited range of services - Only Plain Leased Line Service, Data cards support only up to 64 kbps, no support for N x 64 Kbps. 2. From Operator point of view in case of Leased Line Circuit different boxes from different vendors so difficult to manage & control. 3. No Centralized Monitoring or alarm or performance monitoring. The solution to this is MLLN. 3.3 MLLN ( MANAGED LEASED LINE NETWORK ): The MLLN service is specially designed mainly for having effective control and monitoring on the leased line so that the down time is minimized and the circuit efficiency is increased. This mainly deals with data circuits ranging from 64 Kbps to 2048 Kbps. 3.3.1 MLLN FEATURES: 1. MLLN is an integrated, fully managed, multi service digital network platform through which service provider can offer a wide range of service at an optimal cost to business subscriber. 2. Using NMS, MLLN can provide high speed Leased Line with improved QoS, high availability & reliability. 14
  15. 15. 3. Except for connecting the local lead to the MODEM all operations & maintenance is carried out through ROT (Remote Operating Terminal). 4. NMS supports service provisioning, Network optimization, planning & service monitering. 5. System offers end to end circuit creation and modification, circuit loop testing & fault isolation, automatic rerouting of traffic in case of trunk failure, software programmability of NTU etc. 6. Banking, Financial institution, Stock market, paper industry, broadcasting & Internet service Provider are the main customers for MLLN. 3.3.2 MLLN ADVANTAGES: 1. 24 hrs Performance Monitoring of the circuit. 2. Circuit fault reports generated proactively. 3. On Demand the Bandwidth can be increased. 4. Low lead time for new circuit provisioning. 5. Protection against the failure of the circuit through recovery Management process either automatic or manually. 6. Long drive on single copper pair.( for 64 kbps – 7 kms & for 2mbps – 3.5 kms) 7. Centrally managed from ROT connected to the NMS. 3.3.3 APPLICATION OF MLLN: 1. Corporate high speed internet access through Broadband. 2. LAN interconnection. 3. Hotline connectivity for voice. 4. Point to point connection for data circuit. 5. Point to multipoint connection. 15
  16. 16. CHAPTER-4 INTRANET 4.1 INTRANET: • Smaller private version of Internet. It uses Internet protocols to create enterprise-wide network which may consists of interconnected LANs. • It may or may not include connection to Internet. • Intranet is an internal information system based on Internet technology and web protocols for implementation within a corporate organization. • This implementation is performed in such a way as to transparently deliver the immense informational resources of an organization to each individual’s desktop with minimal cost, time and effort. • The Intranet defines your organization and displays it for everyone to see. 4.2 FEATURES OF INTRANET: 1. It is scalable. 2. It is Interchangeable. 3. It is platform independent 4. It is Hardware independent. 5. It is vendor independent. 4.3 WHY INTRANET FOR AN ORGANIZATION: • Quick access to voice, video, data and other resources needed by users. • Variety of valuable Intranet applications improves communication and productivity across all areas of an enterprise. • A 21st Century Telephone. • An ISO Tool. • A Target Marketing Tool. • A Decision Making Tool. • A Complete Communication Tool. 16
  17. 17. FIG 4.1 INTRANET NETWORK (REF- 5) 4.4 APPLICATIONS OF INTRANET: • Publishing Corporate documents. • Access into searchable directories. • Excellent Mailing Facilities. • Proper Sharing of Information. • Developing Groupware Applications. 4.5 TECHNICAL OVERVIEW OF THE INTRANET TECHNOLOGY Intranet runs on open TCP/IP network, enable companies to employ the same type of servers and browser used for World Wide Web for internal applications distributed over the corporate LAN. A typical Intranet implementation involves a high end machine called a server which can be accessed by individual PCs commonly referred to as clients, through the network. The Intranet site setup can be quite inexpensive, especially if your users are already connected by LAN. 4.6 INTRANET APPLICATIONS IN A CIRCLE: Every circle must have an intranet server which should have the following: • All posting/transfer/relieving orders issued within circle to be hosted on the intranet. 17
  18. 18. • All letters circulars/letters issued from different sections of the circle office to be hosted on the server for immediate access by SSAs. Each section in circle office Administration, Operations, Marketing, Finance, Planning, Computers etc can have web pages hosted on the server. • A database can be maintained for MIS reports and all other reports to be sent periodically by SSAs to circle office. The database can have front end forms designed in ASP or PHP for the SSAs to input the data. Separate programs can be developed to consolidate the data fed by SSAs. • All data prepared and /or distributed during SSA heads meetings can be hosted on the Intranet. • The implementation of the above will reduce the usage of paper and also reduce the usage of FAX. 18
  19. 19. CHAPTER-5 CORPORATE NETWORK 5.1 INTRODUCTION: A corporate network (CN) is a closed and private computer network that affords secure communications between geographically dispersed LANs of an enterprise. Traditional networks • Informal • Socially oriented • Had geographical boundaries • Were expertise specific • No access to corporate resources • Not self sufficient • Not self sustainable • No corporate governance policies An ideal network • Formal • Business oriented • International infrastructure & exposure • Comprehensive expertise • Access to substantial corporate resources • self sufficient • Self sustainable • Governed by strict values and principles TABLE 5.1 DIFFERERCES BETWEEN TRADITIONAL AND IDEAL NETWORKS (REF- 2) The requirement in a Corporate Network is same as ideal network. 5.2 WHY DO BUISNESSES HAVE CORPORATE NETWORK? A business implements a corporate network to share applications and data between different computing devices and users in different locations. Unless the application is web based or database driven, this usually means copying files back and forth between a network drive and a local computer, where a desktop application is used to read and/or edit the files. The increasing need to access corporate data from anywhere has led to changes in the nature of applications, in current model of corporate network. A typical corporate network has the following characteristics: • Many LAN segments. • More than one network protocol (IP or IPX). • OSPF-configured areas, if it uses IP. • Dial-up connectivity for users connecting from home or while traveling. • Connectivity to external networks. • Demand-dial connections to branch offices. 19
  20. 20. • Dedicated circuits to branch offices. • A corporate network typically uses different types of network media. The different office segments can be on 10-MB Ethernet or Token Ring networks, but the backbone network used for connecting the different networks and hosting servers is usually made up of 100-MB Ethernet . Connectivity to external networks (the Internet) is over leased lines. Connectivity to branch offices is either over dial-up line or dedicated media (leased lines). FIG 5.1 CORPORATE NETWORK (REF- 5) 5.3 FEATURES OF CORPORATE NETWORK SECURITY: • Complete bullet-proof protection of the remote computers you have on your network. • Executable patches can be easily uploaded to all your remote computers and executed remotely. • Easy and intuitive configuration without lots of complicated configuration files. Everything is configured through the stand-alone GUI interface from any location where TCP/IP connection to your corporate network can be established. • You do not need to physically visit your workstations when you need to change security settings or install patches. • The remote client service application is bullet-proof. Your users will not be able to disable, uninstall or delete it. • All traffic between the server and the clients is encrypted. All local files are encrypted as well. • The server service application and the remote client service application work as NT services under Windows NT/2000/XP and higher therefore they will keep working in the logoff mode. 20
  21. 21. CHAPTER-6 WI-FI (WIRELESS FIDELITY) 6.1 WI-FI NETWORK: A Wi-Fi network provides the features and benefits of traditional LAN technologies such as Ethernet and Token Ring without the limitations of wires or cables. It provides the final few meters of connectivity between a wired network and the mobile user. WIFI is a wireless LAN Technology to deliver wireless broad band speeds up to 54 Mbps to Laptops, PCs, PDAs, dual mode Wi-Fi enabled phones etc. 6.2 WORKING OF WI-FI NETWORK: In a typical Wi-Fi configuration, a transmitter/receiver (transceiver) device, called the Access Point (AP), connects to the wired network from a fixed location using standard cabling. A wireless Access Point combines router and bridging functions, it bridges network traffic, usually from Ethernet to the airwaves, where it routes to computers with wireless adapters. The AP can reside at any node of the wired network and acts as a gateway for wireless data to be routed onto the wired network. It supports only 10 to 30 mobile devices per Access Point (AP) depending on the network traffic. Like a cellular system, the Wi-Fi is capable of roaming from the AP and re-connecting to the network through another AP. Like a cellular phone system, the wireless LAN is capable of roaming from the AP and re-connecting to the network through other APs residing at other points on the wired network. This can allow the wired LAN to be extended to cover a much larger area than the existing coverage by the use of multiple APs such as in a campus environment. It may be used as a standalone network anywhere to link multiple computers together without having to build or extend a wired network. FIG 6.1WI-FI NETWORK (REF- 5) End users access the Wi-Fi network through Wi-Fi adapters, which are implemented as cards in desktop computers, or integrated within hand-held computers. Wi-Fi 21
  22. 22. wireless LAN adapters provide an interface between the client Network Operating System (NOS) and the airwaves via an antenna. 6.3 BENEFITS OF WI-FI: Wi-Fi offers the following productivity, conveniences, and cost advantages over traditional wired networks: • Mobility: Wi-Fi systems can provide LAN users with access to real-time information anywhere in their organization. • Installation Speed and Simplicity: Installing a Wi-Fi system can be fast and easy and can eliminate the need to pull cable through walls and ceilings. • Installation Flexibility: Wireless technology allows the network to go where wire cannot go. • Reduced Cost-of-Ownership: While the initial investment required for Wi-Fi hardware can be higher than the cost of wired LAN hardware, overall installation expenses and life-cycle costs can be significantly lower. • Scalability: Wi-Fi systems can be configured in a variety of topologies to meet the needs of specific applications and installations. Configurations are easily changed and range from peer-to-peer networks suitable for a small number of users to full infrastructure networks of thousands of users that allows roaming over a broad area. • It offers much high speed up to 54 Mbps which is very much greater than other wireless access technologies like CORDECT, GSM and CDMA. 6.4 LIMITATIONS OF WI-FI: • Coverage: A single Access Point can cover, at best, a radius of only about 60 meters. For 10 square kms area roughly 650 Access Points are required, where as CDMA 2000 1xEV-DO requires just 09 sites. • Roaming: It lacks roaming between different networks hence wide spread coverage by one service provider is not possible, which is the key to success of wireless technology. • Backhaul: Backhaul directly affects data rate service. Wi-Fi real world data rates are at least half of the their theoretical peak rates due to factors such as signal strength, interference and radio overhead .Backhaul reduces the remaining throughput further. • Interference: Wi-Fi uses unlicensed spectrum, which mean no regulator recourse against interference. The most popular type of Wi-Fi, ‘802.11’b uses. 22
  23. 23. CHAPTER-7 WIMAX 7.1 WIRELESS BROADBAND SERVICES: There are two fundamentally different types of broadband wireless services. The first type attempts to provide a set of services similar to that of the traditional fixed-line broadband but using wireless as the medium of transmission. This type, called fixed wireless broadband, can be thought of as a competitive alternative to DSL or cable modem. The second type of broadband wireless, called mobile broadband, offers the additional functionality of portability, nomadicity and mobility. WI-MAX is an acronym that stands for World-wide Interoperability for Microwave Access and this technology is designed to accommodate both fixed and mobile broadband applications. 7.2 SALIENT FEATURES OF WIMAX: • OFDM-based physical layer. • Very high peak data rates. • Scalable bandwidth and data rate support. • Adaptive modulation and coding (AMC). • Link-layer retransmissions. • Support for TDD and FDD OFDMA. • Flexible and dynamic per user resource allocation. • Support for advanced antenna techniques. • Quality-of-service support. • Robust security. • Support for mobility. • IP-based architecture. 7.3 EVOLUTION OF BROADBAND WIRELESS: 23
  24. 24. 1. NARROWBAND WIRELESS LOCAL-LOOP SYSTEMS: The first application for which a wireless alternative was developed and deployed was voice telephony. These systems, called wireless local-loop (WLL). WLL systems based on the digital- enhanced cordless telephony (DECT) and code division multiple access (CDMA) standards continue to be deployed in these markets. During the same time, several small start-up companies focused solely on providing Internet-access services using wireless, antennas to be installed at the customer premises. These early systems typically offered speeds up to a few hundred kilobits per second. Later evolutions of license-exempt systems were able to provide higher speeds. 2. FIRST-GENERATION BROADBAND SYSTEMS: As DSL and cable modems began to be deployed, wireless systems had to evolve to support much higher speeds to be competitive. Very high speed systems, called local multipoint distribution systems (LMDS), supporting up to several hundreds of megabits per second, were developed. In the late 1990s, one of the more important deployments of wireless broadband happened in the so-called multi channel multipoint distribution services (MMDS) band at 2.5GHz. The MMDS band was historically used to provide wireless cable broadcast video services, especially in rural areas where cable TV services were not available. The first generations of these fixed broadband wireless solutions were deployed using the same towers that served wireless cable subscribers. These towers were typically several hundred feet tall and enabled LOS coverage to distances up to 35 miles, using high-power transmitter. The advent of satellite TV ruined the wireless cable business, and operators were looking for alternative ways to use this spectrum. A few operators began to offer one- way wireless Internet-access service, using telephone line as the return path. 3. SECOND - GENERATION BROADBAND SYSTEMS: Second-generation broadband wireless systems were able to overcome the LOS issue and to provide more capacity. This was done through the use of a cellular architecture and implementation of advanced-signal processing techniques to improve the link and system performance under multi path conditions. Many solved the NLOS problem by using such techniques as orthogonal frequency division multiplexing (OFDM), code division multiple access (CDMA), and multi antenna processing. 4. WIMAX AND OTHER BROADBAND WIRELESS TECHNOLOGIES: WIMAX is not the only solution for delivering broadband wireless services. WiMAX occupies a somewhat middle ground between Wi-Fi and 3G technologies when compared in the key dimensions of data rate, coverage, QoS, mobility, and price. 7.3 WIMAX NETWORK ARCHITECTURE: The overall network may be logically divided into three parts: 1. Mobile Stations (MS) used by the end user to access the network. 2. The access service network (ASN), which comprises one or more base stations and one or more ASN gateways that form the radio access network at the edge. 24
  25. 25. 3. Connectivity service network (CSN), which provides IP connectivity and all the IP core network functions. ASN-ACCESS SERVICES NETWORK NAP-NETWORK ACCESS PROVIDER CSN- CORE SERVICES NETWORK NSP- NETWORK SERVICES PROVIDER BS- BAS STATION HA-HOME AGENT FA-FOREGN AGENT AAA-AUTHENTICATION AUTHONZATION & ACCOUNTING FIG 7.1 WIMAX NETWORK ARCHITECTURE (REF- 3) BASE STATION (BS): The BS is responsible for providing the air interface to the MSS. Additional functions that may be part of the BS are micro mobility management functions, such as handoff triggering and tunnel establishment, radio resource management, QoS policy enforcement, traffic classification, DHCP (Dynamic Host Control Protocol) proxy, key management, session management, and multicast group management. ACCESS SERVICE NETWORK GATEWAY (ASN-GW): The ASN gateway typically acts as a layer 2 traffic aggregation points within an ASN. Additional functions that may be part of the ASN gateway include intra-ASN location management and paging, radio resource management and admission control, caching of subscriber profiles and encryption keys, AAA client functionality, establishment and management of mobility tunnel with base stations, QoS and policy enforcement, and foreign agent functionality for mobile IP, and routing to the selected CSN. 25
  26. 26. CONNECTIVITY SERVICE NETWORK (CSN): The CSN provides connectivity to the Internet, ASP, other public networks, and corporate networks. The CSN is owned by the NSP and includes AAA servers that support authentication for the devices, users, and specific services. The CSN also provides per user policy management of QoS and security. The CSN is also responsible for IP address management, support for roaming between different NSPs, location management between ASNs, and mobility and roaming between ASNs, subscriber billing and inter operator settlement, inter-CSN tunneling to support roaming between different NSPs. REFERENCE POINTS: The WiMAX NWG defines a reference point as a conceptual link that connects two groups of functions that reside in different functional entities of the ASN, CSN or MS. Reference points may not be a physical interface except when the functional entities on either side of it are implemented on different physical devices. Reference point End points Description R1 MS and CSN Implements the air interface (IEEE 802.16e) specifications. R2 MS and CSN For authentication, authorization, IP host configuration management and mobility management, only a logical interface between MS and CSN R3 ASN and CSN Supports AAA, policy enforcement,and mobility mgmt. capabilities R4 ASN and ASN A set of protocols originating/terminating in various entities within the ASN. In Release I , R4 is the only interoperable interface between different ASNs or heterogenous ASNs. R5 CSN and CSN A set of protocols for interworking between home and visited network. R6 BS and ASN-GW A set of control and bearer plane protocols for communication between BS and ASN-GW. It may serve as a conduit for exchange of different MAC states information between neighboring BSs. R7 ASN-GW-DP and ASN-GW- EP An optional set of control plane protocols for co-ordination between two group of functions identified in R6. R8 BS and BS A set of control plane message flows and bearer plane data flows between BSs to ensure fast and seamless handover. TABLE 7.1 REFERENCE POINTS (REF- 2) 26
  27. 27. CHAPTER-8 GLOBAL SYSTEM FOR MOBILE COMMUNICATION (GSM) In wireless communication every region is divided into cells. Cell size is constant for whole system. GSM is a form of multiplexing, which divides the available bandwidth among the different channels. Most of the times the multiplexing used is either TDM (Time division multiplexing) or FDM (Frequency Division Multiplexing). SM differs from its predecessor technologies in that both signaling and speech channels are digital, and thus GSM is considered a second generation (2G) mobile phone system. FIG 8.1 (REF- 4) 8.1 MAIN FEATURES OF GSM: • Support for voice and data services • Better frequency efficiency, smaller cells and more customers per cell • High audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g. from cars, trains) i.e. high transmission quality. • Authentication via chip-card and PIN. • Worldwide connectivity. 8.2 GSM SUBSYSTEMS: • RADIO SUBSYSTEM (RSS) • NETWORK AND SWITCHING SUBSYSTEM (NSS) 8.2.1 RADIO SUBSYSTEM: MOBILE STATION (MS): A mobile unit is a transmitter as well as receiver too. It has a SIM (Subscriber Identity Module) which gives a unique identity of a subscriber. Every mobile unit has a unique IMIE (International Mobile Equipment Identity) number. 27
  28. 28. BASE TRANSCEIVER STATION (BTS): • A base transceiver station or cell site (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. • It encodes, encrypts, modulates and feeds the RF signal to antenna. • It produces time and frequency synchronization signals. • It does power control and frequency hopping too. BASE STATION CONTROLLER (BSC): • Its main work is to control several transceivers. • Switching between BTSs • Managing of network resources • Mapping of radio channels 8.2.2 NETWORK AND SWITCHING SUBSYSTEM: This subsystem does mainly switching, mobility management, interconnection to other networks, system control. COMPONENTS: 1. MOBILE SERVICES SWITCHING CENTRE (MSC): It controls all connections via a separated network to/from a mobile terminal within the domain of the MSC – several BSC can belong to a MSC. 2. DATABASES: Home Location Register (HLR): Central master database containing user data, permanent and semi-permanent data of all subscribers assigned to the HLR (one provider can have several HLRs). Visitor Location Register (VLR): Local database for a subset of user data, including data about all user currently in the domain of the VLR. 8.2.3FUNCTION OF MAIN SWITCHING CENTER (MSC): • Manages communication between GSM and other network (PSTN, Data Network and GPRS). • Call setup basic switching, call handling. • Location register • Billing for subscriber 8.3 FEATURES OF GSM: • GSM is already used worldwide with over 450 million subscribers. 28
  29. 29. • International roaming permits subscribers to use one phone throughout Western Europe. CDMA will work in Asia, but not France, Germany, the U.K. and other popular European destinations. • GSM is mature, having started in the mid-80s. This maturity means a more stable network with robust features. CDMA is still building its network. • The availability of Subscriber Identity Modules, which are smart cards that provide secure data encryption give GSM m-commerce advantages. 29
  30. 30. CHAPTER – 9 GENERAL PACKET RADIO SERVICE (GPRS) General packet radio service (GPRS) is a packet oriented mobile data service available to users of the 2G cellular communication systems, global system for mobile communications (GSM), as well as in the 3G systems. In 2G systems, GPRS provides data rates of 56-114 kbps. It provides moderate speed data transfer, by using unused time division multiple access (TDMA) channels. Its supported protocols are Internet Protocol (IP), Point to Point Protocol (PPP) and X.25. GPRS data transfer is typically charged per megabyte of traffic transferred, while data communication via traditional circuit switching is billed per minute of connection time, independent of whether the user actually is using the capacity or is in an idle state. GPRS is a best effort packet switched service, as opposed to circuit switching, where a certain Quality of service (QoS) is guaranteed during the connection for non- mobile users. GPRS extends the GSM circuit switched data capabilities and makes the following services possible: • “ Always on” Internet access • Multimedia messaging service (MMS) • Push to talk over cellular (PoC/PTT) • Instant messaging and presence – wireless village • Internet applications for smart devices through wireless application protocol (WAP) • Point to Point (P2P) service: inter-networking with the internet (IP). • Increase message sending speed 30 messages per minute approximately. 30
  31. 31. CHAPTER- 10 CODE DIVISION MULTIPLE ACCESS (CDMA) Code Division Multiple Access (CDMA) consistently provides better capacity for voice and data communications that other commercial mobile technologies, allowing more subscribers to connect at any given time, and it is the common platform on which 3G technologies are built. CDMA is a spread spectrum technology, allowing many users to occupy the same time and frequency allocations in a given band/space. As it name implies, CDMA assigns unique codes to each communication to differentiate it from others in the same spectrum resources, CDMA enables many more people to share the airwaves at the same time than do alternative technologies. 10.1 ADVANTAGES OF CDMA: • Increased cellular communications security. • Simultaneous conversations • Increased efficiency, meaning that the carrier can serve more subscribers. • Smaller phones • Low power requirements and little cell-to-cell coordination needed by operators. • Extended reach-beneficial to rural users situated far from cells. 10.2 DISADVANTAGES OF CDMA: • Due to its proprietary nature, all of CDMA’s flaws are not known to the engineering community. • CDMA is relatively new, and the network is not as mature as GSM. • CDMA cannot offer international roaming, a large GSM advantage. 10.3 DIFFERENCE BETWEEN CDMA AND GSM: • The GSM stands for global system for mobile communication and CDMA for code division multiple accesses. • GSM is a form of multiplexing, which divides the available bandwidth among the different channels. Most of the times the multiplexing used are either TDM (Time Division Multiplexing) or FDM (Frequency Division Multiplexing). On the other hand CDMA is a type of multiple access scheme (which means allotting the given bandwidth to multiple users) and makes use of spread spectrum technique which is essentially increasing the size of spectrum. • In CDMA each user is provided a unique code and all the conversations between 2 users are coded. This provides a greater level of security to CDMA users than the GSM ones. 31
  32. 32. CHAPTER- 11 FIBER OPTIC TRANSMISSION SYSTEM 11.1 INTRODUCTION: Optical Fiber is new medium, in which information (voice, Data or Video) is transmitted through a glass or plastic fiber, in the form of light, following the transmission sequence give below : (1) Information is encoded into Electrical Signals. (2) Electrical Signals are converted into light Signals. (3) Light Travels down the Fiber. (4) A Detector Changes the Light Signals into Electrical Signals. (5) Electrical Signals are decoded into Information. FIG 11.1 OPTICAL FIBER TRANSMISSION (REF- 1) 11.2 ARCHITECTURE OF FIBER: The optical fiber has two concentric layers called the core and the cladding. The inner core is the light carrying part. The surrounding cladding provides the difference refractive index that allows total internal reflection of light through the core. The index of the cladding is less than 1%, lower than that of the core. Most fibers have an additional coating around the cladding. This buffer coating is a shock absorber and has no optical properties affecting the propagation of light within the fiber. 32
  33. 33. Jacket Cladding Core Cladding Angle of reflection Angle of incidence Light at less than critical angle is absorbed in jacket Jacket Light is propagated by total internal reflection Jacket Cladding Core (n2) (n2) Fig. Total Internal Reflection in an optical Fibre FIG 11.2 PROPAGATION OF LIGHT THROUGH FIBRE (REF- 1) 11.3 CLASSIFICATION: There are three types of fibers: (I) Multimode Step Index fiber (Step Index fiber) (II) Multimode graded Index fiber (Graded Index fiber) (III) Single- Mode Step Index fiber (Single Mode fiber) (I) STEP-INDEX MULTIMODE FIBER: It has a large core, up to 100 microns in diameter. As a result, some of the light rays that make up the digital pulse may travel a direct route, whereas others zigzag as they bounce off the cladding. This type of fiber is best suited for transmission over short distances, in an endoscope, for instance. (II) GRADED-INDEX MULTIMODE FIBER: It contains a core in which the refractive index diminishes gradually from the center axis out toward the cladding. The higher refractive index at the center makes the light rays moving down the axis advance more slowly than those near the cladding. A digital pulse suffers less dispersion. (III) SINGLE-MODE FIBER: It has a narrow core (eight microns or less), and the index of refraction between the core and the cladding changes less than it does for multimode fibers. Light thus travels parallel to the axis, creating little pulse dispersion. Telephone and cable television networks install millions of kilometers of this fiber every year. 11.4 ADVANTAGES OF FIBRE OPTICS: • SPEED: Fiber optic networks operate at high speeds - up into the gigabits. • BANDWIDTH: large carrying capacity. • DISTANCE: Signals can be transmitted further without needing to be refreshed or strengthened. • RESISTANCE: Greater resistance to electromagnetic noise such as radios, motors or other nearby cables. • MAINTENANCE: Fiber optic cables costs much less to maintain. 33
  34. 34. CHAPTER- 11 Advanced Optical Networks: DWDM (DENSE WAVELENGTH DIVISION MULTIPLEXING) INTRODUCTION The revolution in high bandwidth applications and the explosive growth of the Internet, however, have created capacity demands that exceed traditional TDM limits. To meet growing demands for bandwidth, a technology called Dense Wavelength Division Multiplexing (DWDM) has been developed that multiplies the capacity of a single fiber. DWDM systems being deployed today can increase a single fiber’s capacity sixteen fold, to a throughput of 40 Gb/s. The emergence of DWDM is one of the most recent and important phenomena in the development of fiber optic transmission technology. Dense wavelength-division multiplexing (DWDM) revolutionized transmission technology by increasing the capacity signal of embedded fiber. One of the major issues in the networking industry today is tremendous demand for more and more bandwidth. Before the introduction of optical networks, the reduced availability of fibers became a big problem for the network providers. However, with the development of optical networks and the use of Dense Wavelength Division Multiplexing (DWDM) technology, a new and probably, a very crucial milestone is being reached in network evolution. The existing SONET/SDH network architecture is best suited for voice traffic rather than today’s high-speed data traffic. To upgrade the system to handle this kind of traffic is very expensive and hence the need for the development of an intelligent all-optical network. Such a network will bring intelligence and scalability to the optical domain by combining the intelligence and functional capability of SONET/SDH, the tremendous bandwidth of DWDM and innovative networking software to spawn a variety of optical transport, switching and management related products.In traditional optical fiber networks, information is transmitted through optical fiber by a single light beam. In a wavelength division multiplexing (WDM) network, the vast optical bandwidth of a fiber (approximately 30 THz corresponding to the low-loss region in a single mode optical fiber) is carved up into wavelength channels, each of which carries a data stream individually. The multiple channels of information (each having a different carrier wavelength) are transmitted simultaneously over a single fiber. The reason why this can be done is that optical beams with different wavelengths propagate without interfering with one another. When the number of wavelength channels is above 20 in a WDM system, it is generally referred to as Dense WDM or DWDM. DWDM technology can be applied to different areas in the telecommunication networks, which includes the backbone networks, the residential access networks, and also the Local Area Networks (LANs). Among these three areas, developments in the DWDM-based backbone network are leading the way, followed by the DWDM-based LANs. 34
  35. 35. DEVELOPMENT OF DWDM TECHNOLOGY Early WDM began in the late 1980s using the two widely spaced wavelengths in the 1310 nm and 1550 nm (or 850 nm and 1310 nm) regions, sometimes called wideband WDM. The early 1990s saw a second generation of WDM, sometimes called narrowband WDM, in which two to eight channels were used. These channels interval of about 400 GHz in the 1550-nm window. By the mid-1990s, dense WDM (DWDM) systems were emerging with 16 to 40 channels and spacing from 100 to 200 GHz. By the late 1990s DWDM systems had evolved to the point where they were capable of 64 to 160 parallel channels, densely packed at 50 or even 25 GHz intervals. As fig. 1 shows, the progression of the technology can be seen as an increase in the number of wavelengths accompanied by a decrease in the spacing of the wavelengths. Along with increased density of wavelengths, systems also advanced in their flexibility of configuration, through add-drop functions, and management capabilities. 35
  36. 36. CONCLUSION Engineering student will have to serve in the public and private sector industries and workshop based training and teaching in classroom has its own limitation. The lack of expo sure to real life, material express and functioning of industrial organization is the measure hindrance in the student employment. In the open economy era of fast modernization and tough competition, technical industries should procedure pass out as near to job function as possible. Practical training is one of the major steps in this direction. I did my training from BSNL, Bharatpur which is one of the best known communication service provider companies of India. The training helps me in gaining in depth knowledge of the working of telephone exchange, various technologies of BSNL –GSM, GPRS, WIMAX, Wi-Fi, MLLN and optical fiber transmission. In the end, I hereby conclude that I have successfully completed my industrial training on the above topics. 36
  37. 37. BIBLIOGRAPHY AND REFERENCES (I) BIBLIOGRAPHY: 1. Data Communication And Networking- Behrouz A. Foruzan 2. Wireless Communication and Networks-William Stallings 3. Computer Networking – Kurose & Ross (II) REFERENCES: 4. www.bsnl.co.in 5. www.newbsnl.co.in 37

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