MOBILE COMPUTING Unit 1.pptx
- 1. 20CS501- MOBILE COMPUTING Unit – I INTRODUCTION Presented By K.Karthick M.E(Ph.D.) Assistant Professor/CSE, Kongunadu College of Engineering And Technology.
- 2. UNIT I INTRODUCTION Mobile Computing - Mobile Computing Vs wireless Networking - Mobile Computing Applications - Characteristics of Mobile computing - Structure of Mobile Computing Application. MAC Protocols - Wireless MAC Issues - Fixed Assignment Schemes - Random Assignment Schemes - Reservation Based Schemes. UNIT II INTERNET PROTOCOL AND TRANSPORT LAYER Mobile IP- Packet Delivery- Overview of Mobile IP - Features of Mobile IP - Key Mechanism in Mobile IP - Route Optimization. Dynamic Host Configuration Protocol- Overview of TCP/IP - Architecture of TCP/IP- Adaptation of TCP Window - Improvement in TCP Performance. UNIT III TELECOMMUNICATION SYSTEM Cellular Mobile communication- Global System for Mobile Communication (GSM) - General Packet Radio Service (GPRS) - Generation of Mobile communication - SDR. UNIT IV AD-HOC NETWORKS Ad-Hoc Basic Concepts - Characteristics - Applications - Design Issues - Routing - Essential of Traditional Routing Protocols -Routing Protocols - Vehicular Ad Hoc networks (VANET) - MANET Vs VANET - Security. UNIT V PLATFORMS AND APPLICATIONS Basic Concepts- Special Constraints & Requirements - Commercial Mobile Operating Systems - Software Development Kit: iOS, Android, BlackBerry, Windows Phone - M-Commerce - Structure - Pros & Cons - Mobile Payment System - Security Issues
- 3. • Mobile Computing - Mobile Computing Vs wireless Networking - Mobile Computing Applications - Characteristics of Mobile computing - Structure of Mobile Computing Application. MAC Protocols - Wireless MAC Issues - Fixed Assignment Schemes - Random Assignment Schemes - Reservation Based Schemes. Unit – I INTRODUCTION
- 4. • Objectives: • The student should be made to: • Understand the basic concepts of mobile computing • Be familiar with the network protocol stack • Learn the basics of mobile telecommunication system • Be exposed to Ad-Hoc networks • Gain knowledge about different mobile platforms and application development
- 5. • Mobile Computing = Mobility + Computing • Mobility – Capability to change location while communicating to invoke computing services at some remote computers – Kinds of Mobility • User mobility • Refers to a user who has access to the same or similar telecommunication services at different places • Computing – Capability to automatically carry out certain processing related to service locations on a remote computer
- 6. Mobile Computing • Mobile Computing is a technology that allows transmission of data, voice and video via a computer or any other wireless enabled device without having to be connected to a fixed physical link. The main concept involves • Mobile communication • Mobile hardware • Mobile software
- 7. • Mobile Communication • Mobile Communication specifies a framework that is responsible for the working of mobile computing technology. • In this case, mobile communication refers to an infrastructure that ensures seamless and reliable communication among wireless devices. • This framework ensures the consistency and reliability of communication between wireless devices. • The mobile communication framework consists of communication devices such as protocols, services, bandwidth, and portals necessary to facilitate and support the stated services. • These devices are responsible for delivering a smooth communication process. • Mobile communication can be divided in the following four types: • Fixed and Wired • Fixed and Wireless • Mobile and Wired • Mobile and Wireless
- 8. • Fixed and Wired: In Fixed and Wired configuration, the devices are fixed at a position, and they are connected through a physical link to communicate with other devices. • For Example, Desktop Computer. • Fixed and Wireless: In Fixed and Wireless configuration, the devices are fixed at a position, and they are connected through a wireless link to make communication with other devices. • For Example, Communication Towers, WiFi router
- 9. • Mobile and Wired: In Mobile and Wired configuration, some devices are wired, and some are mobile. They altogether make communication with other devices. • For Example, Laptops. • Mobile and Wireless: In Mobile and Wireless configuration, the devices can communicate with each other irrespective of their position. They can also connect to any network without the use of any wired device. • For Example, WiFi Dongle.
- 10. • Mobile Hardware • Mobile hardware consists of mobile devices or device components that can be used to receive or access the service of mobility. • Examples of mobile hardware can be smartphones, laptops, portable PCs, tablet PCs, Personal Digital Assistants, etc. • Mobile Software • Mobile software is a program that runs on mobile hardware. This is designed to deal capably with the characteristics and requirements of mobile applications. • This is the operating system for the appliance of mobile devices.
- 11. History and Evolution of Mobile Computing • The main idea of Mobile computing was evolving since the 1990s. It has evolved from two-way radios to modern day communication devices. • Devices used in Mobile Computing • Following is the list of most common forms of devices used in mobile computing:
- 12. • 1. Portable Computers • A portable computer is a computer that is designed in a way that you can move it from one place to another. • It includes a display and a keyboard. Generally, portable computers are microcomputers. • 2. Personal Digital Assistant/Enterprise Digital Assistant (PDA or EDA) • A Personal Digital Assistant (PDA) is also known as a palmtop computer. Sometimes, it is also called Enterprise Digital Assistant (EDA). • A personal Digital Assistant (PDA) is a mobile device used to function as a personal information manager or a personal data assistant.
- 13. • 3. Ultra-Mobile PC • An ultra-mobile PC was a small form factor version of a pen computer. • It was a class of laptops whose specifications were launched by Microsoft and Intel in 2006. • 4. Laptop • A laptop is a small, portable personal computer (PC) built in a foldable device. The folding structure of a laptop is called a clamshell form factor. • The flip or clamshell is a form factor of a mobile phone or other devices that include two or more folded sections via a hinge. A laptop typically has a thin LCD or LED
- 14. • 5. Smartphone • A smartphone is a mobile device that combines cellular and mobile computing functions into one unit. The smartphones are invented to provide more advanced computing capability and connectivity than basic feature phones. 6. Tablet Computers • A tablet computer is generally known as a tablet. It is a mobile computer with a mobile operating system and a touch-screen display processing circuit, and a rechargeable battery in a single, thin and flat unit
- 15. MOBILE COMPUTING Vs WIRELESS NETWORKING • The terms "mobile" and "wireless" are often used interchangeably but in reality, they are two very different concepts applied to modern computing and technology.
- 16. • Mobile is a word that is commonly used to describe portable devices. A mobile device is one that is made to be taken anywhere. • Therefore, it needs an internal battery for power, and must be connected to a modern mobile network that can help it to send and receive data without attaching to a hardware infrastructure.
- 17. • Wireless, on the other hand, does not mean mobile. Traditional computers or other non- mobile devices can access wireless networks. • One very common example is the use of a localized browser product in a local area network (LAN), where the router takes what used to be a cabled interaction and makes it wireless. • Other kinds of wireless networks called wide area networks (WAN) can even use components of 3G or 4G wireless systems made specifically for mobile devices, but that doesn‘t mean that the devices on these networks are mobile. • They may still be plugged in or require proximity to a router or network node.
- 18. Application VEHICLES • • VEHICLES • Transmission of news, road condition, weather, music, etc., • Personal communication using GSM/UMTS • Position via GPS • Local ad-hoc network with vehicles close-by to prevent accidents, guidance system, redundancy • Vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance
- 19. Application EMERGENCIES • Assume that an ambulance with a high-quality wireless connection is connected to a hospital – Information about injured persons is sent to the hospital from the scene of the accident to • Prepare necessary steps for this particular type of accident • Consult the specialists for an early diagnosis • Wireless networks are the only means of communication during natural disasters such as hurricanes or earthquakes than wired networks – Only decentralized, wireless ad-hoc networks survive
- 20. Application BUSINESS • Businessman needs instant access to the company’s database to – Ensure that files on laptop reflect the current situation – Enable the company to keep track of all activities of their travelling employees, – Keep database consistent etc. • With wireless access, efficient and powerful synchronization mechanisms are needed to ensure data consistency when laptop is turned into a true mobile office
- 21. Location dependent services • Location dependent services are those services that allow the user to connect and use services that are available in their surrounding area. • Location aware services – what services, e.g., printer, phone, server etc. exist in the local environment • Follow-on services – Automatic call-forwarding • Forwarding calls to the current user location by assigning a temporary phone number to the user's actual phone • Allows the user to redirect incoming calls to the user location
- 22. • Information services – Allows the user to pull down information about the location and the service – Example • push- current special offers in the supermarket • pull - where is the Black Forrest Cheese Cake? • Support services – Service that the user utilizes as a result of its location – Caches, intermediate results, state information etc. follow the mobile device through the fixed network
- 23. CHARACTERISTICS OF MOBILE COMPUTING A communication device can exhibit any one of the following characteristics: • ➢ Fixed and wired: • This configuration describes the typical desktop computer in an office. Neither weight nor power consumption of the devices allow for mobile usage. The devices use fixed networks for performance reasons. • ➢ Mobile and wired: • Many of today’s laptops fall into this category; users carry the laptop from one hotel to the next, reconnecting to the company’s network via the telephone network and a modem. • ➢ Fixed and wireless: • This mode is used for installing networks, e.g., in historical buildings to avoid damage by installing wires, or at trade shows to ensure fast network setup.
- 24. • Mobile and wireless: • This is the most interesting case. No cable restricts the user, who can roam between different wireless networks. Most technologies discussed in this book deal with this type of device and the networks supporting them. Today’s most successful example for this category is GSM with more than 800 million users.
- 25. • Ubiquity - Ability of a user to perform computations from anywhere and at any time. • Location Awareness- Can provide information about the current location of a user to a tracking station. • Adaptation- GPS Implies the ability of a system to adjust bandwidth fluctuation without inconveniencing the user. • Broadcast- Efficient delivery of data can be made simultaneously to hand reads of mobile users. • Personalization- Services in a mobile environment can be easily personalized according to a user’s profile
- 26. Structure of Mobile Computing Application – It is structured based on the functionality implementations • Most of them are 3 tier architecture
- 29. • Presentation Tier – Top most level of mobile computing application. – Good user interface that is responsible to produces the results in a meaningful manner. – Runs on client side. – Compatible with browsers and customized client applications. – E.g. : Flip kart Interface
- 30. • Application Tier – Vital responsibility of this layer is making logical decisions and • performing calculations. It moves and process the data between presentation and data tiers. – It is also considered engine of the application. – It gets the user input information and process with the logic and makes the decisions. – It is implemented using the technology like Java, .NET services.
- 31. • Data Tier – It provides the basic facilities of data. • Storage. • Access. • Manipulations. – This layer contains databases and Query processors. – This layer implemented in the fixed server. – voiding dependencies on the storage mechanisms allows for updates or changes without the application tier clients being affected by or even aware of the change. •
- 32. GENERATIONS OF MOBILE COMMUNICATION TECHNOLOGIES • First Generation • Second Generation • Third Generation • Fourth Generation • Fifth Generation
- 33. GENERATIONS OF MOBILE COMMUNICATION TECHNOLOGIES • First Generation • Second Generation • Third Generation • Fourth Generation • Fifth Generation
- 34. First Generation • It uses analog technology that were introduced in the 1980s and continued until being replaced by 2G digital telecommunications It introduces the following mobile technologies • Mobile Telephone System (MTS) • Advanced Mobile Telephone System (AMTS) • Improved Mobile Telephone Service (IMTS) • Push to Talk (PTT)
- 35. Features • Maximum speed of 1G is 2.4 Kbps • Allows voice calls in 1 country • Use analog signal • Channel bandwidth 30khz Disadvantage • Poor Voice Quality • Poor Battery Life • Large Phone Size • No Security • Limited Capacity
- 36. Second Generation • Second Generation based on GSM. • It was launched in Finland in the year 1991. • It uses digital signals for voice transmission. • It make use of either CDMA or TDMA.
- 37. Features • Lower power emissions • Data speed was upto 64kbps • Use digital signals • Enables services such as text messages, picture messages and MMS(Multimedia message) Provides better quality and capacity Limitations • Requires powerful digital signals to work the mobile phones • Unable to handle complex data such as videos
- 38. Third Generation • It make use of TDMA and CDMA. • It provides value added services like mobile television, GPS (global positioning system), live streaming and video conferencing. • It is designed for multimedia communication
- 39. Features • Fast data transfer rates • Speed 2 Mbps • Send/receive large email messages • Provide seamless global roaming Limitations • Requires higher bandwidth • Cost is high
- 40. Fourth Generation • It is an all IP-based integrated system will be capable to provide 100 Mbps for high mobility and 1 Gbps. • The user services include IP telephony, ultra- broadband Internet access, gaming services and High Definition Television (HDTV) streamed multimedia.
- 41. Feature • Capable of provide 10Mbps-1Gbps speed • High quality streaming video • Combination of Wi-Fi and Wi-Max • High security • Low cost per-bit Limitations • Battery uses is more • Hard to implement • Need complicated hardware • Expensive equipment required to implement next generation network
- 42. Fifth Generation • Its not yet have been deployed and are still at a research and development phase • Increased data transmission capability 1 Gbps • Connectivity to a large number of devices due to the IoT. • Period of establishment 2016 to 2020.
- 43. MULTIPLEXING • Multiplexing is a technique in which, multiple simultaneous analog or digital signals are transmitted across a single data link. For wireless communication, multiplexing can be carried out in four dimensions: • Space • Time • Frequency • Code
- 44. SPACE DIVISION MULTIPLEXING • Space Division can be called as the combination of concepts of Frequency Division Multiplexing and Time Division Multiplexing • Pass messages or data parallelly with the use of specific frequency at certain interval of time • Particular channel for some amount of time will be used against a certain frequency band
- 46. • Diagram shows six channels ki and introduces a three dimensional coordinate systems. This system shows the dimension of code c, time t, and frequency f. For this type of multiplexing, space division multiplexing (SDM), the (three dimensional ) space si is also shown. • The channels k1 to k3 can be mapped onto the three spaces s1 to s3 which clearly separate the channels and prevent the interference ranges from overlapping. For the channels (k4 to k6) three additional spaces will be needed.
- 47. FREQUENCY DIVISION MULTIPLEXING • FDM describe to several overlapping frequency • Each channel ki is now allotted its own frequency band as indicated • Senders using a certain frequency band can use this band continuously. Again guard spaces are needed to avoid frequency band overlapping
- 49. Advantages • Applicable on both analog signals as well as digital signals • Simultaneous signal transmission feature Disadvantages • Less Flexibility • Bandwidth wastage is high and can be an issue
- 50. TIME DIVISION MULTIPLEXING • When data transmission rate of media is greater than that of the source, and each signal is allotted a definite amount of time. • These slots are so small that all transmissions appear to be parallel. • In frequency division multiplexing all the signals operate at the same time with different frequencies, • but in time division multiplexing all the signals operate with same frequency at different times.
- 52. • Advantages • Single user at a time • Less complex and more flexible architecture Disadvantages • Difficult to implement
- 53. CODE DIVISION MULTIPLEXING • Every channel is allotted with a unique code so that each of these channels can use the same spectrum simultaneously at same time • Channels ki use the same frequency at the same time for transmission • Each channel its own ‘code’
- 55. Advantages • Highly Efficient • Less Inference • Good protection against interference and tapping Disadvantages • Less data transmission rates • Complex in nature
- 56. SPREAD SPECTRUM • Technique that involve spreading the bandwidth needed to transmit data • Spreading the spectrum is the resistance to narrowband interference Two different way to achieve spread spectrum • Direct sequence spread spectrum • Frequency hopping spread spectrum
- 57. Significance of Spread Spectrum • Immunity to jamming • Low interference • Higher processing gain • Multiple access
- 58. Direct sequence spread spectrum (DSSS) • DSSS is one of the most popular and transmission methods in the wireless communications • Narrow band signals are spread over much wider band
- 59. Step by step process of DSSS • At the sending end the original data are going into a spreading modulator • Pseudo noise called a chipping sequence is added and mixed in the modulator • The chipping sequence are much higher bit rate sequence, a series of 0s and 1s. • The spreading modulator transmit the modulator signal at a much wider band. • At the receiving end the received signal is demodulated with a chipping sequence and original data are restored.
- 61. FREQUENCY HOPPING SPREAD SPECTRUM (FHSS) • Total available bandwidth is split into many channels of smaller bandwidth plus guard spaces between the channels • Transmitter and receiver stay on one of these channels for a certain time and then hop to another channel
- 63. MAC Protocols • MAC stands for Media Access Control. A MAC layer protocol is the protocol that controls access to the physical transmission medium on a LAN • (MAC) data communication Networks protocol sub-layer, also known as the Medium Access Control, is a sub-layer of the data link layer specified in the seven-layer OSI model • It acts as an interface between the Logical Link Control
- 64. Design issues of MAC Protocol • Bandwidth Efficiency – The shortage of data transfer capacity assets in these networks requires its proficient use. To evaluate this, we could state that bandwidth capacity is the proportion of the bandwidth used for data transmission to the complete accessible bandwidth capacity. • Quality of Service Support – Quality of service support is difficult due to the mobility of the nodes. Once a node moves out of reach, the reservation in it is lost. In these networks, QoS is extremely important because if it is being used in military environments, the service support needed time to time.
- 65. Synchronization – Some instruments must be found so as to give synchronization among the nodes. Synchronization is significant for directing the bandwidth reservation. Hidden Terminal Problem – When there are two nodes, both are outside of each other’s range and try to communicate with same node within their range at the same time, then there must be packet collision. Exposed Terminal Problem – Uncovered nodes might be denied channel access pointlessly, which implies under usage of the bandwidth resources.
- 66. MAC Issues 1. Hidden terminal problem • A hidden node is one that is within the range of the intended destination but out of range of sender it causes collisions 2. Exposed terminal problem • An exposed node is one that is within the range of the sender but out of range of destination it causes unnecessary delay
- 68. Classification of MAC Protocols
- 69. Fixed Assignment Schemes Strict Sharing
- 70. Fixed Assignment Schemes ❖ It is also called as circuit switched scheme. ❖ The Resource or Channel is shared by nodes based on Time, Frequency or Code. ❖ There are three types of schemes available ➢ Frequency Division Multiple Access ( FDMA ). ➢ Time Division Multiple Access ( TDMA ). ➢ Code Division Multiple Access ( CDMA ).
- 72. Frequency Division Multiple Access ( FDMA ) Channel 1 Channel 2 Channel 3 Channel 4 Channel 5 Channel 6 Frequency Available Bandwidth
- 73. Frequency Division Multiple Access ( FDMA ) ❖ In FDMA the available bandwidth is divided into many narrow frequency band called channels. ❖ Each user need a two link ➢ Forward link ( Mobile to Base Station ). ➢ Reverse Link ( Base Station to Mobile ). ❖ Two channels are allocated to one user. ❖ These 2 channels are unable to allocate to other users while on use.
- 75. Time Division Multiple Access Ch 1 Ch 2 …. Ch N Ch 1 Ch2 ... Ch N Ch 1 Ch 2 ... Ch N Time Frame
- 76. Time Division Multiple Access ( TDMA ) ❖ TDMA allows the user to use multiple channels based on different time slots. ❖ All sources are uses the same channel but it will wait for time slots. ❖ The time slots are allocated in the round robin manner. ❖ Unused time slot makes the channel idle so this to leads to poor utilization of channel.
- 78. Code Division Multiple Access Code 1 Code 2 Code 3 Channel
- 79. Code Division Multiple Access ( TDMA ) ❖ In CDMA Technology multiple users can use the same channel same time. ❖ No scheduling is needed. ❖ Message or data is encoded in the one end and decoded in the other end. ❖ Quite expensive procedure when compared to FDMA and TDMA.
- 80. Random Assignment Scheme Everybody Owns a Chance
- 81. • In this protocol, all the station has the equal priority to send the data over a channel. In random access protocol, one or more stations cannot depend on another station nor any station control another station. • Depending on the channel's state (idle or busy), each station transmits the data frame. However, if more than one station sends the data over a channel, there may be a collision or data conflict. • Due to the collision, the data frame packets may be lost or changed. And hence, it does not receive by the receiver end.
- 82. Types of Schemes ❖ ALOHA. ❖ Slotted ALOHA. ❖ CSMA. ➢ CSMA/CD. ➢ CSMA/CA.
- 83. ALOHA Don’t Wait
- 84. ALOHA Scheme ❖ Whenever data is available for sending over a channel at stations, we use Pure Aloha. In pure Aloha, when each station transmits data to a channel without checking whether the channel is idle or not, the chances of collision may occur, and the data frame can be lost. ❖ When any station transmits the data frame to a channel, the pure Aloha waits for the receiver's acknowledgment.
- 85. ● If it does not acknowledge the receiver end within the specified time, the station waits for a random amount of time, called the backoff time (Tb). ● And the station may assume the frame has been lost or destroyed. Therefore, it retransmits the frame until all the data are successfully transmitted to the receiver.
- 86. Aloha
- 87. Slotted ALOHA Scheme ● The slotted Aloha is designed to overcome the pure Aloha's efficiency because pure Aloha has a very high possibility of frame hitting. In slotted Aloha, the shared channel is divided into a fixed time interval called slots. ● So that, if a station wants to send a frame to a shared channel, the frame can only be sent at the beginning of the slot, and only one frame is allowed to be sent to each slot.
- 88. ● And if the stations are unable to send data to the beginning of the slot, the station will have to wait until the beginning of the slot for the next time. However, the possibility of a collision remains when trying to send a frame at the beginning of two or more station time slot.
- 89. Slotted Aloha
- 90. CSMA Scheme ❖ CSMA = Carrier Sense Multiple Access. ❖ Before the transmission begins the node check with a medium for traffic and it defers the transmission rate. ❖ Two Techniques ➢ CSMA/CD ➢ CSMA/CA
- 91. CSMA (Carrier Sense Multiple Access) ● It is a carrier sense multiple access based on media access protocol to sense the traffic on a channel (idle or busy) before transmitting the data. It means that if the channel is idle, the station can send data to the channel. Otherwise, it must wait until the channel becomes idle. Hence, it reduces the chances of a collision on a transmission medium.
- 92. Reservation Based Scheme Everybody Owns a Chance
- 93. Reservation Based Scheme ❖ The scheme is based on RTS/CTS Signals ➢ RTS = Ready To Send ➢ CTS = Clear To Send ❖ Before the transmission node must send RTS Signal to receiver and ❖ Receiver sends CTS Signal and engages with transmission. ❖ Other nodes must wait until the data transmission is completed.
- 94. CSMA Access Modes ● 1-Persistent: In the 1-Persistent mode of CSMA that defines each node, first sense the shared channel and if the channel is idle, it immediately sends the data. Else it must wait and keep track of the status of the channel to be idle and broadcast the frame unconditionally as soon as the channel is idle.
- 95. ● Non-Persistent: It is the access mode of CSMA that defines before transmitting the data, each node must sense the channel, and if the channel is inactive, it immediately sends the data. Otherwise, the station must wait for a random time (not continuously), and when the channel is found to be idle, it transmits the frames.
- 96. ● P-Persistent: It is the combination of 1- Persistent and Non-persistent modes. The P- Persistent mode defines that each node senses the channel, and if the channel is inactive, it sends a frame with a P probability. If the data is not transmitted, it waits for a (q = 1-p probability) random time and resumes the frame with the next time slot.
- 97. ● O- Persistent: It is an O-persistent method that defines the superiority of the station before the transmission of the frame on the shared channel. If it is found that the channel is inactive, each station waits for its turn to retransmit the data.
- 98. CSMA/ CD ● It is a carrier sense multiple access/ collision detection network protocol to transmit data frames. The CSMA/CD protocol works with a medium access control layer. Therefore, it first senses the shared channel before broadcasting the frames, and if the channel is idle, it transmits a frame to check whether the transmission was successful.
- 99. ● If the frame is successfully received, the station sends another frame. If any collision is detected in the CSMA/CD, the station sends a jam/ stop signal to the shared channel to terminate data transmission. After that, it waits for a random time before sending a frame to a channel.
- 100. Reservation Based Scheme ❖ To avoid collision with RTS and CTS Signal each node must wait in random time slot send or receive RTS or CTS Signal.