Real Time GPS Tracker with Integrated Google

This project describes how you can build a mobile real time GPS tracker with integrated Google Maps.

How it works?

In a nutshell, this is how the GPS Tracker works. The GPS chip outputs the positioning information which is transferred over a GPRS link to the mobile operator’s GGSN (Gateway GPRS Support Node) and then to a remote server over a TCP connection. The TCP server stores the incoming positional data in a mySQL database. When a user clicks on the tracking page, Zope, which is an open source web application server, serves up an HTML page with an embedded javascript code. The javascript would run in the user's browser and has instructions to retrieve the positional information from the mySQL database every second. It then integrates this information into Google Maps through Google Maps API which displays the position on a map. Since the positional information is retrieved every second and the maps updated at the same frequency, a real time GPS tracking effect is achieved.

How much does it cost?

The costs are all associated with the hardware components. There is no software costs involved, since everything is open source.

HARDWARE

The hardware consists of three main components.

• Microcontroller

• GSM/GPRS Module

• GPS Module

Microcontroller :-

A micro-controller is a small computer (SoC) on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Program memory in the form of Ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a typically small amount of RAM. Micro-controllers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips.

Micro-controllers are used in automatically controlled products and devices, such as automobile engine control systems, implantable medical devices, remote controls, office machines, appliances, power tools, toys and other embedded systems. By reducing the size and cost compared to a design that uses a separate microprocessor, memory, and input/output devices, micro-controllers make it economical to digitally control even more devices and processes. Mixed signal micro-controllers are common, integrating analog components needed to control non-digital electronic systems.

GSM/GPRS Module:-

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe the protocols for second-generation (2G) digital cellular networks used bymobile phones, first deployed in Finland in July 1991. As of 2014 it has become the default global standard for mobile communications - with over 90% market share, operating in over 219 countries and territories.
2G networks developed as a replacement for first generation (1G) analog cellular networks, and the GSM standard originally described a digital, circuit-switched network optimized for full duplex voice telephony. This expanded over time to include data communications, first by circuit-switched transport, then by packet data transport via GPRS (General Packet Radio Services) and EDGE (Enhanced Data rates for GSM Evolution or EGPRS).Subsequently, the 3GPP developed third-generation (3G) UMTS standards followed by fourth-generation (4G) LTE Advanced standards, which do not form part of the ETSI GSM standard."GSM" is a trademark owned by the GSM Association. It may also refer to the (initially) most common voice codec used, Full Rate.

GPS Module

A GPS navigation device is a device that accurately calculates geographical location by receiving information from GPS satellites. Initially it was used by the United States military, but now most receivers are in automobiles and smartphones.
The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of a minimum of 24, but currently 30, satellites placed into orbit by the U.S. Department of Defense. Military action was the original intent for GPS, but in the 1980s, the U.S. government decided to allow the GPS program to be used by civilians. The satellite data is free and works anywhere in the world.
GPS devices may have capabilities such as:

• maps, including street maps, displayed in human readable format via text or in a graphical format,

• turn-by-turn navigation directions to a human in charge of a vehicle or vessel via text or speech,

• directions fed directly to an autonomous vehicle such as a robotic probe,

• traffic congestion maps (depicting either historical or real time data) and suggested alternative directions,

• information on nearby amenities such as restaurants, fueling stations, and tourist attractions.

• GPS devices may be able to indicate:

• the roads or paths available,

• traffic congestion and alternative routes,

• roads or paths that might be taken to get to the destination,

• if some roads are busy (now or historically) the best route to take,

• The location of food, banks, hotels, fuel, airports or other places of interests,

• the shortest route between the two locations,

• the different options to drive on highway or back roads.

About Latitude and Longitude

A key geographical question throughout the human experience has been, "Where am I?"

In classical Greece and China, attempts were made to create logical grid systems of the world to answer this question. The ancient Greek geographer Ptolemy created a grid system and listed the coordinates for places throughout the known world in his book Geography. But it wasn't until the middle ages that the latitude and longitude system was developed and implemented. This system is written in degrees, using the symbol °.

Latitude and longitude are angles that uniquely define points on a sphere. Together, the angles comprise a coordinate scheme that can locate or identify geographic positions on the surfaces of planets such as the earth.

Latitude

In geography, latitude (φ) is a geographic coordinate that specifies the north–south position of a point on the Earth's surface. Latitude is an angle (defined below) which ranges from 0° at the Equator to 90° (North or South) at the poles. Lines of constant latitude, or parallels, run east–west as circles parallel to the equator. Latitude is used together with longitude to specify the precise location of features on the surface of the Earth. Two levels of abstraction are employed in the definition of these coordinates. In the first step the physical surface is modeled by the geode, a surface which approximates the mean sea level over the oceans and its continuation under the land masses. The second step is to approximate the geode by a mathematically simpler reference surface. The simplest choice for the reference surface is a sphere, but the geode is more accurately modeled by an ellipsoid. The definitions of latitude and longitude on such reference surfaces are detailed in the following sections. Lines of constant latitude and longitude together constitute a gratitude on the reference surface. The latitude of a point on the actual surface is that of the corresponding point on the reference surface, the correspondence being along the normal to the reference surface which passes through the point on the physical surface. Latitude and longitude together with some specification of height constitute a geographic coordinate system as defined in the specification of the ISO 19111 standard

Since there are many different reference ellipsoids the latitude of a feature on the surface is not unique: this is stressed in the ISO standard which states that "without the full specification of the coordinate reference system, coordinates (that is latitude and longitude) are ambiguous at best and meaningless at worst". This is of great importance in accurate applications, such as GPS, but in common usage, where high accuracy is not required, the reference ellipsoid is not usually stated.

In English texts the latitude angle, defined below, is usually denoted by the Greek lower-case letter phi (φ or ɸ). It is measured in degrees, minutes and seconds or decimal degrees, north or south of the equator.

Measurement of latitude requires an understanding of the gravitational field of the Earth, either for setting up theodolites or for determination of GPS satellite orbits. The study of the figure of the Earth together with its gravitational field is the science of geodesy. These topics are not discussed in this article. (See for example the textbooks by Torge and Hofmann-Wellenhof and Moritz.)

Meridian distance on the sphere

On the sphere the normal passes through the centre and the latitude (φ) is therefore equal to the angle subtended at the centre by the meridian arc from the equator to the point concerned. If the meridian distance is denoted by m(φ) then

where R denotes the mean radius of the Earth. R is equal to 6,371 km or 3,959 miles. No higher accuracy is appropriate for R since higher precision results necessitate an ellipsoid model. With this value for R the meridian length of 1 degree of latitude on the sphere is 111.2 km or 69 miles. The length of 1 minute of latitude is 1.853 km, or 1.15 miles.

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter lambda (λ). Meridians (lines running from the North Pole to the South Pole) connect points with the same longitude. By convention, one of these, the Prime Meridian, which passes through the Royal Observatory, Greenwich, England, was allocated the position of zero degrees longitude. The longitude of other places is measured as the angle east or west from the Prime Meridian, ranging from 0° at the Prime Meridian to +180° eastward and −180° westward. Specifically, it is the angle between a plane containing the Prime Meridian and a plane containing the North Pole, South Pole and the location in question. (This forms a right-handed coordinate system with the z axis (right hand thumb) pointing from the Earth's center toward the North Pole and the x axis (right hand index finger) extending from Earth's center through the equator at the Prime Meridian.)
A location's north–south position along a meridian is given by its latitude, which is approximately the angle between the local vertical and the plane of the Equator.
If the Earth were perfectly spherical and homogeneous, then the longitude at a point would be equal to the angle between a vertical north–south plane through that point and the plane of the Greenwich meridian. Everywhere on Earth the vertical north–south plane would contain the Earth's axis. But the Earth is not homogeneous, and has mountains—which have gravity and so can shift the vertical plane away from the Earth's axis. The vertical north–south plane still intersects the plane of the Greenwich meridian at some angle; that angle is the astronomical longitude, calculated from star observations. The longitude shown on maps and GPS devices is the angle between the Greenwich plane and a not-quite-vertical plane through the point; the not-quite-vertical plane is perpendicular to the surface of the spheroid chosen to approximate the Earth's sea-level surface, rather than perpendicular to the sea-level surface itself.

Length of a degree of longitude

The length of a degree of longitude (east-west distance) depends only on the radius of a circle of latitude. For a sphere of radius a that radius at latitude φ is (cos φ) times a, and the length of a one-degree (or π/180 radians) arc along a circle of latitude is

	(km)	(km)
0°	110.574	111.320
15°	110.649	107.551
30°	110.852	96.486
45°	111.132	78.847
60°	111.412	55.800
75°	111.618	28.902
90°	111.694	0.000

When the Earth is modelled by an ellipsoid this arc length becomes

where e, the eccentricity of the ellipsoid, is related to the major and minor axes 

(the equatorial and polar radii respectively) by

An alternative formula is

where  

Cos φ decreases from 1 at the equator to zero at the poles, which measures how circles of latitude shrink from the equator to a point at the pole, so the length of a degree of longitude decreases likewise. This contrasts with the small (1%) increase in the length of a degree of latitude (north-south distance), equator to pole. The table shows both for the WGS84 ellipsoid with a = 6,378,137.0 m and b = 6,356,752.3142 m. Note that the distance between two points 1 degree apart on the same circle of latitude, measured along that circle of latitude, is slightly more than the shortest (geodesic) distance between those points (unless on the equator, where these are equal); the difference is less than 0.6 m.

A geographical mile is defined to be the length of one minute of arc along the equator (one equatorial minute of longitude), so a degree of longitude along the equator is exactly 60 geographical miles, as there are 60 minutes in a degree.

How to Disable a Cell Phone's GPS Tracking System?

Many cell phones today have dedicated sensors that can determine your location using GPS satellites. These sensors provide support for some very useful applications, such as turn-by-turn navigation. There are some reasons why you may wish to disable this support, and it is easy to do so. Disabling the GPS when you are not using it can improve the battery life of your phone. Your phone's camera also uses the GPS to encode the location of each photo that you take with it, and you may wish to disable this to protect your privacy.

Apple iPhones

Step 1

Tap the "Settings" icon and then tap "Privacy."

Step 2

Tap "Location Services."

Step 3

Tap the "On" switch next to "Location Services" to put it in the "Off" position.

Step 4

Tap the "On" switch next to individual applications in the list below to disable GPS for specific applications only.

Android phones (4.0 and up)

Step 1

Tap the application launcher on your phone's Home screen.

Step 2

Tap the "Settings" application.

Step 3

Scroll down to the "Personal" category and tap "Location services."

Step 4

Tap the item labeled "GPS satellites" if it is checked, to disable the GPS.

The Main Steps

Press the menu or enter key on your cell phone to enter the main menu. Some touchscreen phones allow you to simply press a menu icon on the screen to enter the phone's main menu.

Look for an entry in the menu labeled "Location," "Options" or "Settings." The GPS location-sharing option could be listed under a different menu heading depending on the manufacturer of the phone. Some phones contain a listing under "Options" or "Settings" called "E911" that will allow you to disable the tracking feature.

Use your phone's arrow keys or touchscreen to highlight the option to disable the location or GPS system. Press the "Enter" or "OK" key to select the option to disable the location-tracking system. Some cell phones provide only an "On" and "E911" option instead of an option to disable tracking completely. If you select "E911," only a 911 call center operator will be able to see your location if you call from your cell phone to report an emergency.

What is E911?

E911 (Enhanced 911) is a system adopted by the U.S. FCC (Federal Communications Commission) that tracks the number of the mobile within 100 meters. The government requires all wireless service providers to include such features to instantly identify and locate callers during emergency situations.

Enhanced 911, E-911 or E911 is a system used in North America that links emergency callers with the appropriate public resources. Three-digit emergency telephone numbers originated in the United Kingdom in 1937 and have spread to continents and countries around the globe. Other easy dial codes, including the 112 number adopted by the European Union in 1991, have been deployed to provide free-of-charge emergency calls.

In North America, where 9-1-1 was chosen as the easy access code, the system tries to automatically associate a location with the origin of the call. This location may be a physical address or other geographic reference information such as X/Y map coordinates. The caller's telephone number is used in numerous manners to track a location that can be used to dispatch police, fire, emergency medical and other response resources. Automatic location of the emergency makes it faster to locate the required resources during fires, break-ins, kidnappings, and other events where communicating one's location is difficult or impossible.

In North America the incoming 9-1-1 call is normally answered at the Public Safety Answering Point (PSAP) of the governmental agency that has jurisdiction over the caller's location (see #Location below). When the 9-1-1 call arrives at the appropriate PSAP, it is answered by a specially trained official known as a Telecommunicator. In some jurisdictions the Telecommunicator is also the dispatcher of public safety response resources. When a landline call arrives at the PSAP, special computer software uses the telephone number to retrieve and display the location of the caller in near real-time upon arrival of the call.

Does GPS Work in the Snow?

Salespeople, truck drivers and other mobile professionals depend on Global Positioning System devices to help them navigate safely through their busy workdays. A GPS unit determines location based on radio signals it receives from satellites in space. The signals are relatively unaffected by weather conditions, so you can expect your GPS to provide reliable directions even in snow.

GPS Basics

 The U.S. Department of Defense originally developed the Global Positioning System during the 1980s as a way to coordinate military efforts. The system consists of a minimum of 24 satellites orbiting the Earth, each broadcasting its own precise time code signal. A GPS receiver picks up the signals from at least four satellites at any one moment; the combined information yields an accurate location in terms of latitude, longitude and altitude.

Weather Effects on Radio Waves

The atmosphere affects radio waves in a few different ways. The upper region, called the ionosphere, can reflect radio transmissions, and dust and moisture can absorb and scatter radio waves. A complex relationship exists between the wavelength of radio waves and how they interact with the atmosphere and weather. Airborne moisture, for example, absorbs some types of microwave signals, which have wavelengths of a few centimeters. AM radio, which has wavelengths of hundreds of meters, bounces off the ionosphere, allowing you to hear nighttime broadcasts from distant cities. GPS uses two radio frequencies, 1575.42 MHz and 1227.60 MHz, which have wavelengths of 18 and 24 centimeters. Rain and snow have little effect on these frequencies.

  

Weather and GPS Accuracy

According to the University of Colorado, changes in the troposphere, the lower layer of the atmosphere in which weather occurs, slightly affect the accuracy of GPS location data. Pressure, temperature and humidity across long distances can alter GPS readings by up to one meter. In terms of navigating through a town or across a state, one-meter accuracy poses no problems to most business users.

Snow and GPS

Because the military needs to function in all kinds of weather, the Department of Defense selected GPS radio frequencies that were unaffected by rain or snow. A snowstorm in progress does not absorb GPS signals, and snow and ice on the ground do not absorb or reflect them. You can rely on GPS directions in difficult winter weather because snow does not hinder the GPS unit's performance.

GPS Navigators

How Do GPS Navigators Work?

GPS navigators are devices that collect radio signals from a network of satellites to provide you with real-time, instantly updated information about your current location. These units may focus on automotive, maritime or aeronautical use, or they may be handheld units for hikers and outdoor enthusiasts, but they all use the same system to provide information. As long as your GPS navigator has unblocked access to the sky, it can guide you to your next destination.

Satellites

The key to the GPS system is a network of satellites orbiting the Earth. These satellites, maintained by the United States Air Force, travel in carefully monitored orbits in order to provide each region on earth as much coverage as possible. There are at least 24 active satellites at any given time, with extras for redundancy purpose. Generally between four and nine satellites cover any point on the globe at any moment. As long as a GPS navigator can pick up signals from at least four satellites, it can provide accurate positional data, but more signals can provide an even more precise reading.

How it Work?

When you activate your GPS navigator, it searches the sky for signals. Each satellite broadcasts a steady stream of information giving its current location and the time of the broadcast’s origin, and since radio waves travel at a set speed, the navigator can use that data to pinpoint exactly how far it is from each satellite. Once the navigator has distance readings from multiple satellites, it can plot those distances to identify its location in three-dimensional space to within a few meters. The navigator can then compare that point to its internal map database to provide you with information about your area, and give you the ability to navigate to another point on the map with accurate directions.

Maintenance

Most of the maintenance of the GPS network is completely transparent to the end-user, but it is vital in keeping the system running and providing accurate data. The US Air Force tracks each satellite carefully, comparing its actual orbit to its planned path through the sky, and tracking stations note any deviations. Small orbital inaccuracies simply require adjustment to the satellite’s positional signal, but if one of the craft fails entirely, it can affect the accuracy of GPS readings in the affected region. To keep the network functioning at peak efficiency, the Air Force maintains extra satellites in orbit, and launches new craft to replace old or damaged satellites as needed.

Problems

One common GPS problem is a reflected signal. If you are near a mountain or a large building, the signal from a satellite may reflect off its surface, providing your navigator with more than one reading from the same satellite. However, since these reflected signals take longer to arrive, the navigator can compare them with other signals to calculate which one is correct. In canyons or other areas with multiple reflections, however, this can hamper the accuracy of your navigator until you reach a clearer area.

The First GPS Satellite of India

Indian Regional Navigation Satellite System

IRNSS-1C is the third out of seven in the Indian Regional Navigation Satellite System series of satellites. The satellite was successfully launched using India's PSLV-C26 from the Satish Dhawan Space Centre at Sriharikota on 16 October 2014 at 1:32 am.

The Indian Regional Navigation Satellite System or IRNSS is an indigenously developed Navigation Satellite System that is used to provide accurate real-time positioning and timing services over India and region extending to 1500 km around India. The fully deployed IRNSS system consists of 3 satellites in GEO orbit and 4 satellites in GSO orbit, approximately 36,000 km altitude above earth surface.However, the full system comprises nine satellites, including two on the ground as stand-by. The requirement of such a navigation system is driven because access to foreign government-controlled global navigation satellite systems is not guaranteed in hostile situations, as happened to the Indian military depending on American GPS during the Kargil War. The IRNSS would provide two services, with the Standard Positioning Service open for civilian use, and the Restricted Service (an encrypted one) for authorized users (including the military). IRNSS would have seven satellites, out of which five are already placed in orbit. The constellation of seven satellites is expected to operate from June 2016 onwards.
 

Satellites

 

IRNSS-1A

IRNSS-1A was the first navigational satellite in the Indian Regional Navigation Satellite System series of satellites to be placed in geosynchronous orbit. It was built at ISRO Satellite Centre, Bangalore, costing ₹125 crore (US$18 million). It has a lift-off mass of 1380 kg, and carries a navigation payload and a C-band ranging transponder, which operates in L5 band (1176.45 MHz) and S band (2492.028 MHz). An optimised I-1K bus structure with a power handling capability of around 1600 watts is used and is designed for a ten-year mission. The satellite was launched on-board PSLV-C22 on 1 July 2013 from the Satish Dhawan Space Centre at Sriharikota.

IRNSS-1B

IRNSS-1B is the second out of seven in the Indian Regional Navigation Satellite System. It was very precisely and successfully placed in its orbit through PSLV-C24 rocket on 4 April 2014

IRNSS-1C

IRNSS-1C is the third out of seven in the Indian Regional Navigation Satellite System series of satellites. The satellite was successfully launched using India's PSLV-C26 from the Satish Dhawan Space Centre at Sriharikota on 16 October 2014 at 1:32 am.

IRNSS-1D

IRNSS-1D is the fourth out of seven in the Indian Regional Navigation Satellite System series of satellites system. It was successfully launched using India's PSLV-C27 on 28 March 2015 at 5:19 pm.

IRNSS-1E

IRNSS-1E is the fifth out of seven in the Indian Regional Navigation Satellite System series of satellites system. It was successfully launched on 20 January 2016 using India's PSLV-C31 at 09:31 am.

IRNSS-1F and IRNSS-1G

IRNSS-1F will be the sixth and IRNSS-1G will be seventh of the Indian Regional Navigation Satellite System series of satellites. Their launches are planned for March 10th and 31st resp. 

Time-frame

In April 2010, it was reported that India plans to start launching satellites by the end of 2011, at a rate of one satellite every six months. This would have made the IRNSS functional by 2015. But program was delayed. India also launched 3 new satellites into space to supplement this.

Seven satellites with the prefix "IRNSS-1" will constitute the space segment of the IRNSS. IRNSS-1A, the first of the seven satellites of the IRNSS constellation, was launched on 1 July 2013. IRNSS-1B was launched on 4 April 2014 at 17:14 IST on board the PSLV-C24 rocket. The satellite has been placed in geosynchronous orbit. IRNSS-1C was launched on 16 October 2014, IRNSS-1D on 28 March 2015 and IRNSS-1E was launched on 20 January 2016 Of the  remaining two satellites, IRNSS-1F has a planned launch in March 2016 and IRNSS-1G should be in orbit by April 2016 and by middle of 2016, India will have the full navigational satellite system in place.

GPRS

General Packet Radio Service

General Packet Radio Service (GPRS) is a packet oriented mobile data service on the 2G and 3G cellular communication system's global system for mobile communications (GSM). GPRS was originally standardized by European Telecommunications Standards Institute (ETSI) in response to the earlier CDPD and i-mode packet-switched cellular technologies. It is now maintained by the 3rd Generation Partnership Project (3GPP).

GPRS usage is typically charged based on volume of data transferred, contrasting with circuit switched data, which is usually billed per minute of connection time. Usage above the bundle cap is charged per megabyte, speed limited, or disallowed.

GPRS is a best-effort service, implying variable throughput and latency that depend on the number of other users sharing the service concurrently, as opposed to circuit switching, where a certain quality of service (QoS) is guaranteed during the connection. In 2G systems, GPRS provides data rates of 56–114 kbit/second. 2G cellular technology combined with GPRS is sometimes described as 2.5G, that is, a technology between the second (2G) and third (3G) generations of mobile telephony. It provides moderate-speed data transfer, by using unused time division multiple access (TDMA) channels in, for example, the GSM system. GPRS is integrated into GSM Release 97 and newer releases.

GPRS Network Architecture

GPRS network architecture

Packet Control Unit(PCU)- This PCU is the core unit to segregate between GSM and GPRS traffic. It separates the circuit switched and packet switched traffic from the user and sends them to the GSM and GPRS networks respectively which is shown in the figure above. In GPRS PCU has following two paths. 

1. PCU-MSC-GMSC-PSTN 
2. PCU-SGSN-GGSN-Internet (packet data network)

Serving GPRS Support Node(SGSN)- It is similar to MSC of GSM network. SGSN functions are outlined below

1. Data compression which helps minimise the size of transmitted data units.
2. Authentication of GPRS subscribers.
3. Routing of data to the corresponding GGSN when a connection to an external network is needed.
4. Mobility management as the subscriber moves from one PLMN area to the another PLMN, and possibly one SGSN to another SGSN.
5. Traffic statistics collections. 

Gateway GPRS Support Node(GGSN)- GGSN is the gateway to external networks such as PDN (packet data network) or IP network. It does two main functions. It is similar to GMSC of GSM network.

1. Routes mobile destined packet coming from external IP networks to the relevant SGSN within the GPRS network.
2. Routes packets originated from a user to the respective external IP network.

Border Gateway(BG)- It is a kind of router which interfaces different operators GPRS networks. The connection between two border gateways is called GPRS tunnel. It is more secure to transfer data between two operators using their own PLMN networks through a direct connection rather than via the public Internet which is less secure. For this both operators need to agree to provide such connectivity and terms and conditions including charging terms.

Charging Gateway(CG)- GPRS users have to be charged for the use of the network, this is taken care by Charging gateway. Charging is done based on Quality of Service or plan user has opted either prepaid or post paid. This charging data generated by all the SGSNs and GGSNs in the network is referred to as Charging Data Records (CDRs). The Charging Gateway (CG) collects all of these CDRs, processes the same and passes it on to the Billing System.

DNS server- Connected at ISP location or at IP network. It converts domain name to IP addresses required to establish internet connection and to deliver web pages on user's terminal screen.

Intra PLMN- An IP based network inter-connecting all the above mentioned GPRS network elements in one PLMN area.

Inter PLMN- Connection between two different PLMN areas. 

GPRS Frame Structure 

Let us examine frame structure as part of GPRS tutorial now. GPRS uses FDMA to divide 25 MHz to 124 channels and each channel is further divided using TDMA into 8 time slots similar to GSM. Each of the frequency and time slot make one physical channel. We have seen that in GSM 26 Frame MF(Multiframe) and 51 Frame MF is used for traffic/SACCH and Signaling channels respectively. Logical channels are time multiplexed on physical channels.In GPRS 52 Frame MF structure is used for traffic as well as signalling. Each time slot follow 52 frame MF structure. Resource allocation here is called radio block or RLC block. 4 consecutive bursts in 4 consecutive TDMA frames in the same time slot is called radio block. In GPRS frame structure of 52 frame MF consists of 12 radio blocks for user data, 2 PTCCH frames for the Timing advance calculation and 2 idle frames used for neighbour cell measurements. Only for few of the initial network entry logical frames such as FCCH,SCH and BCCH 51 Frame MF structure of GSM is used in GPRS. Figure 2. depicts GPRS 52 frame Multiframe structure. PTCCH frames are marked by T and Idle frames by X. As shown it requires four consecutive time slots(carrying bursts) in four consecutive TDMA frames to fill 456 data bits. each burst carry 114 bits.

Different logical frames goes in these 12 blocks both in the downlink and uplink to carry signalling as well as traffic (data).

1 TDMA Frame = 8 TNs(Time Slot Nos)(4.615 ms)

One 52 Frame MF = 4.615 (52) = 240 ms

One super frame = 25.5 (52 Frame MF) = 240 x 25.5 = 6.12 sec

One hyperframe = 2048 (6.12 sec) = 3 h 28 min 53 sec 760 ms

Remember that UEs to BSS link is called uplink and BSS to UEs link is called downlink.Unlike GSM where time slot is dedicated to UE/MS, in GPRS one time slot is used by multiple UEs at different time. UEs are multiplexed using unique USF (Uplink Status Flag) on same time slot. USF helps differentiate UEs on BSS side. On downlink UEs are multiplexed using TFI (Temporary Flow Identity ) which differentiate concurrent TBFs (Temporary Block Flows). 

GPRS Channel types

Let us go through logical channels used in GPRS as part of GPRS tutorial. Logical channels are named and used in GPRS network are PBCCH, PPCH, PAGCH,PNCH,PRACH, PACCH,PTCCH,PDTCH. These channels are divided as mentioned below based on their functions. 

1. Broadcast channel- Packet Broadcast Central Channel (PBCCH) 
2. Common control channels- Packet Paging Channel (PPCH),Packet Access Grant Channel (PAGCH),Packet Notification Channel (PNCH),Packet Random Access Channel (PRACH) 
3. Dedicated control channels-Packet Associated Control Channel (PACCH),Packet Timing Advance Common Control Channel (PTCCH) 
4. Dedicated traffic channel-Packet Data Traffic Channel (PDTCH) 
5. GPRS Logical Channel functions are described below. 
6. PDTCH- Used for data traffic, bidirection between MS(Mobile Subscriber) and BSS(base station subsystem) 
7. PBCCH- Used for Broadcast signalling control, from BSS to MSs 
8. PRACH- Used for random access, from MSs to BSS 
9. PAGCH- Used for Access Grant indication, from BSS to MSs 
10. PPCH-Used for Paging, from BSS to MSs 
11. PNCH- USed for notification purpose, from BSS to MSs 
12. PACCH- Used for Associated control, bidirectional 
13. PTCCH- Used for timing advance control, bidirectional 

Field force automation and its's Key Challenges

There are a number of businesses that have a direct sales force or a number of staff working across different locations in various parts of the country or the world. They may be selling products face-to-face to your clients or they may be taking products back or they may even be collecting information or making people fill up forms. How do we manage this huge workforce that is out there on the field and doing their jobs? How do you tally the results with the investment or even better, try and make changes to existing field plans?

It is increasingly clear that there needs to be a certain sense of discipline and streamlining of field operations. This is one of the reasons why it is important to automate certain tasks within field sales and operations. This helps you to track your assets remotely and contact with your workforce when required.

In this article, let us take a look at what field force management is and how it is going to help you.

Why you must choose field force management?

Field force management tools help you to stay in control all the time. They automate what can be automated and leave only the most human-human interaction left to your staff. This helps you to keep a record of all interactions and important data within a database, without you having to manually go through sales receipts, complaint slips and other such details. In other words, a field force management tool is a godsend to companies.

Moreover, these tools help to automate several aspects of your staff’s work, leading to an increase in productivity and motivation. By streamlining operations, you will also ensure that important stakeholders are well informed and management visibility is enhanced. This helps you to make smarter decisions and finally help you to serve your customers better.

Cloud based solutions help you automate better?

Field Force Management is usually cloud based which means all data is stored and accessible on secure cloud servers. There is no question of losing important data or not being able to retrieve something important. If something goes missing, there will usually be a backup available. Field force management tools include the software, the hardware and also the kind of training that is required for users to use it efficiently.

The software usually helps in saving and processing information while the hardware helps employees to enter important data into devices while they are on the job. Sometimes, field force solutions can also be a mobile app which negates the need for a specific or special device. This is very important when it comes to field jobs as carrying different devices can prove to be a cumbersome job.

The actual process of field force management?

A field force management tool helps you to remain in contact with your staff while they are at work on the field. This helps you to track your personnel in real time. Field personnel or your staff can log in and enter their attendance using a smartphone. You can assign that particular day’s task remotely using a web console or your own smartphone.

Next, they can carry out whatever duties they need to while you get all the alerts that you set to receive. This helps to increase transparency. You can choose to receive alerts on your phone or on your desktop.

Key Challenges in Traditional Field Force Management

There are numerous challenges in traditional methods of field force management, some of them are: 

1. Inadequate visibility of the field operations which result in disorganized work and extra overhead.
2. Poor communication between manager and field force leads to rework and anxiety.
3. Sub-optimal client service due to slower respose time. 
4. Randomly assigning of tasks causing dissatisfaction amongst the employees. 
5. Traditional Paper based tasks allotment, leading to a time consuming and less productive operations.
6. High operating and administrative cost. 
7. Lack of optimum utilization of resources. 
8. Risk of not meeting agreed SLAs.
9. Lack of communication between the on-site resources and planner/scheduler leads to delay in work execution.
10. Lack of visibility on the work that is executed at a remote location and hence it becomes difficult to manage the productivity of these resources.
11. Prioritization of work becomes a challenge.
12. Grouping of work for a particular location does not happen in an optimum manner.
13. Inaccurate allocation of resources as per required skills.
14. Delay in the reactions on the feedback received from the field resources.