CELLULAR POSITIONING Seminar presented By : SOORAJ KUMAR 1JS04EC090

A PERSON LOST HIS PATH

INTRODUCTION

What is cellular positioning?Network-based services that integrate a derived estimate of a mobile device's location or position with other information so as to provide added value to the user.AIMTo design simplest method of tracking and positioning the mobile with high accuracy

NEED FOR TRACKING & POSITIONINGTo obtain the geo-location of the Mobile Telephone in the cellular system To allow the network operators to facilitate new services to the mobile users such as: Emergency service for subscriber safety.

Location sensitive billing.

Cellular Fraud detection and many more.

Mobile Communication Network

MOBILE NETWORKEACH CELL SITE HAVE CONTROL CHANNELSFORWARD AND REVERSE CHANNELMOBILE SCANS FOR STRONGEST FWD CHANNEL,LOCKS ONTO IT,GET INFO FOR FREE REVERSE CHANNELTRANSMITS REGISTRATION MESSAGE ALONG WITH CELL ID

PRESENT TECHNOLOGIESCell IDNETWORK BASED MOBILE POSITIONING TIME OF ARRIVAL (TOA) TIME DIFFERENCE OF ARRIVAL (TDOA)ANGLE OF ARRIVAL (AOA) NETWORK ASSISTED GLOBAL POSITIONING SYSTEM (GPS) RECEIVER BASED (E-OTD (Enhanced Observed time Difference))

Cell ID

Cell IDMost basic wireless location technologyUsed to locatelat/long of cell siteradius of coverageRelative accuracy is very low and depends on size of cellMay be improved by techniques such as TOA

NETWORK BASED MOBILE POSITIONINGMobile telephone network locates the mobile telephone

At least three base stations (BSs) are required The implementation requires accurate synchronization of each BS.

TOA (TIME OF ARRIVAL)ONE SHOULD NOT CONFUSED BETWEEN TOA AND TDOATOA AND TDOA ARE DIFFERENTTOA USES ABSOLUTE TIME OF ARRIVAL OF THE SIGNALSDISTANCE IS CALCULATED DIRECTLY WITH KNOWN VELOCITY OF S/GTOA DATA FROM 2 BS NARROW POSITION ,DATA FROM 3 RD BS ESTIMATES ACCURATE POSITION

ESTIMATION OF POSITIONTIME OF TRANSMISSION (TOT) MUST BE KNOWNCALCULATES THE TOA OF SIGNALS,TAKE THE DIFFERENCE,WHICH IS TOTAL TIME OF PROPAGATION OF SIGNAL ,MULTIPLY WITH VELOCITY AND ESTIMATES A RANGE OF LOCATIONTHIS RANGE DEFINES A CIRCLE

CIRCULAR TRILATERATION (TOA)Ri = C i = sqrt ( (xi X ) 2 + (yi Y) 2 )

PROBLEM IN TOATOA requires exact time synchronization between the base stations The receiver should have an accurate clock, so that the receiver knows the exact time of transmission and an exact TOA of transmitted signals

TOA

TDOAUSES LOCATION RECEIVERSUSES SIGNAL PROPAGATION TIMESIGNAL RECEPTION IS TIME STAMPEDDIFFERENCE IN TIME STAMPED ARE COMBINE FOR HYPERBOLIC TRILATERATION2 TDOAS ARE REQUIRED FOR 2 UNKNOWN LATTITUDE AND LONGITUDETHE IMPLEMENTATION REQUIRES ACCURATE SYNCHRONIZATION OF EACH BS, FOR THAT IT USES ATOMIC CLOCKS

HYPERBOLIC TRILATERATION

TDOA

TDOA Highlights

Extremely valuable for "mission critical" applications where every phone must be able to be located, in every environment, such as safety and security ( medical alert, child finder, mobile surveillance, and more) Location available for start-of-call, mid-call, or when idle Locates by both voice and SMS messaging Completely network-based; no additional chip or software needs to be installed into the handset, meaning it can locate all mobile phones

CONTINUEDTDOA or Time Difference of Arrival uses multiple (three or more) receivers to locate a mobile device TDOA gives 90% or even better accuracy Accuracy to under 250 meters

PROBLEM IN TDOAMULTIPATH IS THE SINGLE LARGEST ERROR DUE TO REFLECTION OF THE SIGNALS BY MAN MADE AND NATURAL OBJECTS MULTIPATH OCCURS MOSTLY IN DENSE RURAL AREAIN THIS CASE EITHER AOA OR DOA IS USEDTHEN IT COMPUTES LOCATION BASED ON ANGLES

PROBLEM IN TDOA

LOCATION BY TRIANGULATION(BASED ON AOA or DOA)

NETWORK ASSISTED GLOBAL POSITIONING SYSTEM (GPS)Mobile phone is located by itselflocation information is received from a satellite through the GPS receiverUses GPS receiver to calculate its location in latitude and longitude3-D Location calculated by (TOA-TOT) using 3 satellites4 th satellite for offset of rx clockWorks in all weather condition and all propagation environment

CONSTRAINTSIncreases the price and the size of the mobile telephone.The load on the mobile telephone is increased.Power consumption is high Delay is generated to identify available satellites which should not exist in case of emergency callsNot suitable for multipath error and no LOS

RECEIVER BASED (E-OTD (Enhanced Observed time Difference))Uses the same technique that GPS does, but instead of using distant satellites, the mobile unit measures the time required to trade signals with three or more surrounding cellular sites The real time differences (RTD) between pairs of BSs are measured by an LMU(Location Measuring Unit) device computes the clock difference between BSs and send this information to the corresponding BSs. OTD is also calculated b/w pairs of BSs.

E-OTD

TRACKING ALGORITHM

CELLOCATETM SYSTEM

ACCURACY

TechnologyNetworksHandset impactAccuracyCell IDAllnoneDepends on size of cell100m-3kmTDOAAllnone250-350mAOAAllnone100-200mEOTDGSMyes50-200mGPSAllYes5-30m

Which technique is accurate in which area?

BRANDS INVOLVED ALCATEL,MOTOROLA & SIEMENS ARE MAJOR BRANDS INVOLVED IN THIS.DIFFERENT BRAND USES DIFFERENT TECHNIQUE.

Traffic state informationTravel time between two points in comparison to free flow results in a percentage of the delay Traffic state according to the obtained delay: free flow synchronized traffic traffic congestion

Evaluation of traffic state informationTravel time information on the mobile devicePast running timeExpected Travel time (at free flow conditions)Current delay

AssistancePersonal or vehicle emergency, roadside assistance, alarm management APPLICATIONInformationEntertainment, news, weather, traffic & navigation, advertising, find your friendNetwork related Network management, billing, customer care.B2BFleet & freight tracking

M2M & P2P B2CPushed info. Discount, ad, special event M2PC2C Pulled info. Find friend, pets P2PC2BPulled info.Find Gas station,restaurant, P2MRange of applicationsAsset trackingWireless remote management & controlB: BusinessC: Consumer

M: MachineP: Person

Project Theme 4GPS based microsatelliteIndoor positioning options

Project Theme 3GPS, single & network-based receivers Software-defined receiversEmbedded processors GPS Development Kits

military and surveying navigation users consumer electronicsEvolution of the User Segment

APPLICATION (cntd)Used in military like Blue Force Tracking, Red Force Tracking, Border Patrol.

Used in locating stolen mobiles

To make emergency calls

Different billing tariffs depending on where the call is originated

Methods to predict the user movement inside a region

CONCLUSIONPOSITIONING OF ANY CELLULAR DEVICE IS NOT IMPOSSIBE NOW. THE COMPLEX ITY OF SUCH SYSTYEM IS REDUCING DAY BY DAY.ACCURACY OF SYSTEM IS INCREASED DAY BY DAY.