logging in or signing up WIRELESS COMMUNICATION amitsorot Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 3245 Category: Education License: All Rights Reserved Like it (1) Dislike it (0) Added: March 28, 2012 This Presentation is Public Favorites: 2 Presentation Description overview Comments Posting comment... By: tazfatima7 (2 month(s) ago) plz mail me abstract on email@example.com thnk yu in advance(hope u'll send soon) Saving..... Post Reply Close Saving..... Edit Comment Close By: umeraanjum (2 month(s) ago) hello sir... can u please send me this ppt to my mail id firstname.lastname@example.org plzzzzzzzzzzz............. Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript WIRELESS COMMUNICATION: CELLULAR CONCEPTS AMIT SOROT EC-08007 ADVANCED GROUP OF INSTITUTION WIRELESS COMMUNICATIONWHAT IS WIRELESS COMMUNICATION?: Transmitting/receiving voice and data using electromagnetic waves in open space. The information from sender to receiver is carried over a well defined frequency band(channel). Each channel has a fixed frequency bandwidth & capacity(bit rate). Different channels can be used to transmit information in parallel and independently. WHAT IS WIRELESS COMMUNICATION?How communication takes place?: How communication takes place? Transmitting signal Received signal satellite Transmitting antenna Receiving antenna TYPICAL FREQUENCIES: FM RADIO 88 MHZ TV BROADCAST 200 MHZ GSM PHONES 900 MHZ GPS 1.2 GHZ PCS PHONES 1.8 GHZ BLUETOOTH 2.4 GHZ Wi-Fi 2.4 GHZ TYPICAL FREQUENCIESWHY WIRELESS COMMUNICATION?: Freedom from wires. No bunch of wires running from here and there. “Auto Magical” instantaneous communication without physical connection setup e.g.- Bluetooth, Wi-Fi. Global coverage Communication can reach where wiring is infeasible or costly e.g.- rural areas,buildings,battlefield,outerspace. Stay connected,flexiblity to connect multiple devices. WHY WIRELESS COMMUNICATION?TYPES OF WIRELESS COMMUNICATION?: RADIO TRANSMISSION:- easily generated, Omni-directional , travel long distance , easily penetrates buildings. PROBLEMS:- frequency dependent , relatively low bandwidth for data communication , tightly licensed by government. MICROWAVE TRANSMISSION:- widely used for long distance communication , give high S/N ratio , relatively inexpensive. PROBLEMS:- don’t pass through buildings , whether and frequency dependent. TYPES OF WIRELESS COMMUNICATION? TYPES CONTINUED….: INFRARED AND MILIMETER WAVES:- widely used for short range communication , unable to pass through solid objects , used for indoor wireless LANs , not for outdoors. LIGHT WAVE TRANSMISSION:- unguided optical signal such as laser , unidirectional , easy to install , no license required. PROBLEMS:- unable to penetrate rain or thick fog , laser beam can be easily diverted by air. TYPES CONTINUED…. CURRENT WIRELESS SYSTEMS: CELLULAR SYSTEM WIRELESS LANs SATELLITE SYSTEM PAGING SYSTEM PANs(BLUETOOTH) CURRENT WIRELESS SYSTEMSWhat is cellular system?: Definition Wireless communication technology in which several small exchanges (called cells ) equipped with low-power radio antennas (strategically located over a wide geographical area) are interconnected through a central exchange . As a receiver ( cell phone ) moves from one place to the next, its identity , location , and radio frequency is handed-over by one cell to another without interrupting a call. What is cellular system? PracticalCellular system basic concept?: High capacity is achieved by limiting the coverage of each base station to a small geographic region called a cell. Same frequencies timeslots/codes are reused by spatially separated base stations. A switching technique called handoff enables a call to proceed uninterrupted when one user moves from one cell to another. Neighboring base stations are assigned different group of channels so as to minimize the interference. Cellular system basic concept?Cellular system basic concept contd…: By systematically spacing base stations and the channel groups may be reuse as many number of times as necessary. Cellular system basic concept contd… MSC CELLS PSTN SUBSCRIBER UNIT BASE STATIONS Coverage areaHand over ?: Hand over ? BSC BS1 BS2 BS3 Connect to Bs1 & start calling Out of BS1 coverage & connect to BS2 Out of BS2 coverage & connect to BS3 Call endedFREQUENCY REUSE THE NEED?: Cellular radio systems rely on intelligent allocation and reuse of channels throughout the coverage area. Each base station is allocated a group of radio channels to be used within the same geographical area of its cell. Neighboring base stations are given different channel allocation from each other. The design procedure of allocating channel groups for all of the cellular BS within a system is called frequency reuse or frequency planning. FREQUENCY REUSE THE NEED?Example of frequency reuse?: Example of frequency reuse? Co channel cells Co channel cellsHow to find co -channel cell?: Co channels How to find co -channel cell? 60 degree u v DThe geometry of hexagon?: Axes u and v intersect at 60 degree. Unit scale is the distance between center cells. If cell radius to point of hexagon is R then 2Rcos30=1 Or R = 1/√3. to find the distance of a point P(u , v) from the origin we use x-y to u-v coordinate transformation. R² = x² + y² x=ucos30˚ y=u+vsin30˚ r=√(v²+uv+u²) The geometry of hexagon?Geometry contd…: Using this equation to locate co-channel cells we start from reference cell and moves i hexagon along u axis then j hexagon along the v axis. Hence the distance between co-channel cells in adjacent cluster is given by D = √(i²+ij+j²) The number of cells in a cluster N is given by N = √(i²+ij+j²) where i and j are integers. Hence the possible values of N are 1 , 3 , 4 , 7 , 12…… Geometry contd…Co-channel location: Formation of cluster for N=7 Suppose i=2 and j=1 will give co channel cell Same color showing co-channel cells. Co-channel location i=2 j-=1 Co channel cellsWhat is GSM?: Global system for mobile communication is a set of ETSI standards specifying the infrastructure for a digital cellular services. GSM networks are structured hierarchically it consist of one administrative region which is assigned to a MSC . Each administrative region is made up of at least one location area (LA). LA is also called the visited area. An LA consists of several cell groups . Each cell group is assigned to a base station controller (BSC) What is GSM ?GSM system hierarchy?: GSM system hierarchy? GSM NETWORK MSC REGION LOCATION AREA (LA) BS CONTROLLER CELL CELL LA LA BS CONTROLLER BS CONTR-OLLER MSC REGION MSC REGIONOPENED VIEW OF GSM ARCHITECHTURE?: OPENED VIEW OF GSM ARCHITECHTURE? BSC MSC EIR AUC HLR VLR ISDN PSTN OTHER NETWORKS BSS NSS NMS Mobile stationMobile station?: Consist of two main elements. 1. The mobile equipment 2. Subscriber identity module( SIM ). Mobile station?The Base Station Subsystem?: BSS = BSC + BTS The Base Station Subsystem? RADIO PATH CONTROL AIR INTERFACE SIGNALLING CENTRAL N/W ELEMENT OF BSS CALL ESTABLISHMENT MOBILITY MGMT STATISTICAL RAW DATA COLLECTION SPEECH PROCESSING MODULATION/DEMODULATION TRANSCODER MINIMIZE TRANSMISSION PROBLEM AIR INTERFACE MANAGEMENTTHE N/W SWITCHING SUBSYSTEM?: NSS = MSC + HLR + VLR + AUC + EIR THE N/W SWITCHING SUBSYSTEM? MANAGE COMMUNICATION B/W USERS INCLUDE DATABASE TO STORE INFORMATION OF USER CALL CONTROL MOBILITY MGMT SUBSCRIBER DATA HANDLING CHECK IDENTITY OF USER PERMANENT STORAGE OF USER INFORMATION STORE A COPY OF HLR CHECK ROAMING PROVIDE AUTHENTICATION SECURITY CHECK IMEI NUMBER OF MOBILEN/W MANAGEMENT SUBSYSTEM?: N/W MANAGEMENT SUBSYSTEM? 1. MONITORING MANAGE OPERATION 4. MAINTANENCE NMSGSM TECHNOLOGY ?: USE TDMA + FDMA MODULATION USED = GMSK(Gaussian minimum shift keying) UPLINK FREQUENCY = 890 – 915 MHZ DOWNLINK FREQUENCY = 935 – 960 MHZ GSM TECHNOLOGY ?Wireless local area network(WLAN): WLAN connect local computers Range (100 m) confined region Break data into packets Channel access is shared Backbone internet provides best service Poor performance in some application like videos Low mobility Wireless local area network(WLAN)Satellite system ?: Global coverage Different orbit height Optimized for good transmission Expensive base stations. Voice and data transmission Telecommunication application GPS , global telephone connection TV broadcasting , military , whether broadcasting Satellite system ?Paging system ?: Paging system ? Broad coverage for short messages Message broadcast from all base stations Simple terminals Optimized for one way transmission Answer back hard Overtaken by cellular Pager systemWide area paging system ?: Wide area paging system ? PSTN Paging control center Paging terminal Paging terminal Paging terminal Terrestrial link Terrestrial link Satellite link City 1 City 2 City N Base station Base station Base stationPersonal area network ?: Bluetooth Cable replacement RF technology Short range(10m) 2.4 GHz band TDD duplex scheme 1 Mbps data rate shared b/w 7 devices Polling based multiple access Work on frequency hopping spread spectrum technology Personal area network ?Ad-hoc network ?: Peer to peer communication No backbone infrastructure Routing can be multihop Topology is dynamic Fully connected with different link SINRs. Ad-hoc network ?Ad-hoc network contd….: Ad-hoc network provides a flexible network infrastructure for many emerging applications. The capacity of such networks is generally unknown. Transmission , access and routing strategies for these networks are generally ad-hoc. Cross layer design is very critical and challenging. Energy constraints impose interesting design for trade offs communication and networking. Ad-hoc network contd…. You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.