Mobile Computing

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Presentation Transcript

Slide 1: 

Overview of Mobile Computing

Outline : 

Outline What is mobile computing? Mobile computing applications Basic concepts of mobile computing Challenges in mobile computing Topics in mobile computing

What is mobile computing? : 

What is mobile computing? By 2012 the number of mobile subscribers throughout the world will reach 5 Billion, of which close to 1.5 Billion will use wireless communicators (3G) as gateways to the Internet

What is mobile computing? : 

What is mobile computing? World wide Internet penetration rate increases rapidly. 25% of the world population access to the Internet by 2012, >1 billion of Internet users will use mobile as their only access means

What is mobile computing? : 

What is mobile computing? Today, access to information and computing services is necessary everywhere not only from our "home base," but also while we are traveling and when we reach a different location. Mobile computing Techniques that allow mobile users to use portable computing devices to run stand-alone applications and / or to access remote ones via wireless networks.

What is mobile computing? : 

What is mobile computing? Mobile computing = mobile + computing, another wave in computing evolution. Different kinds of mobility Terminal mobility: movement of processors / devices - caused by mobile devices. User mobility: movement of users – caused by traveling people. Logical mobility: movement of processes - caused by mobile codes. Different modes of computing Small office: take the service/application with users - computing is offline Home office: maintain the access to the same service/application at different places – computing is online Mobile office: move to different places and the service/application follows – computing is moving (follow-me)

Evolution of computing paradigm : 

Evolution of computing paradigm 2010 Unwired Enterprise

What is mobile computing? : 

Mobile computing often uses wireless and mobile networks as access technologies. Wireless and mobile networks extend networking capacity to cover the areas of lack of wired link and support movement of devices Wireless communication plays an important role in mobile computing. But, mobile computing does not necessarily mean wireless. What is mobile computing?

Wireless vs mobile : 

Wireless mobile Examples   stationary computer   notebook in a hotel room   wireless LANs in historic buildings   Personal Digital Assistant (PDA) Wireless vs mobile mobile wireless

Today’s applications : 

Today’s applications Internet, Wireless Networks & Mobile Computing Mobile users use wireless communications to access to the Web information and services

Today’s applications : 

Corporations M-business / M-office (working remotely - job dispatch, calendar, email, workflow, etc) M-commerce (logistics, inventory control) Consumers M-commerce (shopping, banking, payment, etc) Mobile web access / mobile email / SMS Mobile P2P (file sharing, gaming, etc.) Government / Public services / Militaries M-healthcare (emergency with in-time patient condition info.) Transportation Tourism (navigation with maps, location-aware travel hints, etc) Intelligent home Environment monitoring Battle field communications Today’s applications

Enabling factors : 

Enabling factors Motivations and driving forces Increasing demands on access to information, communication, and cooperation anywhere, anytime, anyway. Technology reality may support such demands Increasing availability of wireless networks at reduced cost. Widespread use of handheld devices with increasing computing power and lower cost. Integration of communication and computing devices (PDA, i-Phone, smart phone, intelligent sensor). Advances in techniques of detecting location of a device – location based services.

Slide 13: 

Open Mobile Alliance (OMA) No matter what device I have service I want carrier or network I am using I can communicate, access and exchange information Visions

Wireless Vision: ubiquitous communication : 

Wireless Vision: ubiquitous communication

Device Vision : 

Device Vision Mobile phones 1973: First cellphone call 2007: ~ 3.3 billion mobile phone subscribers 2009: ~ 4.6 billion Smart phones are mobile phones have operation systems can connect to the internet: web browsing, email, etc have advanced computing ability: send and receive text & multimedia messages (SMS, MMS), take pictures, etc

Convergences : 

Convergences

Mobile computing means more… : 

Mobile computing means more… Mobile computing has a close relationship with distributed computing Distributed computing: coordination of utilizing computing resources shared by multiple hosts over a network. Mobile computing: extends distributed computing with new dimensions of mobility and wireless connection.

Mobile computing means more… : 

Mobile computing means more… Mobile computing is also closely related to Internet computing technologies Mobile computing uses Internet computing technologies The layered protocol stack and client/server paradigm Mobile computing allows the application not to connect the network all the time Mobile Internet, Wireless Internet HTTP client / server protocols => WAP XML, HTML => WML, XHTML J2SE/J2EE, .Net => J2ME/J2EE, .Net Mobile

Mobile computing means more… : 

Mobile computing means more… Pervasive computing Create a smart environment with ubiquitous, invisible, interconnected devices that provides services to the users without being noticed. Improving users’ experience and quality of life without requiring them know the underlying technologies. Mark Weiser, “The Computer for the 21st Century,” Sci. Amer., Sept., 1991. “The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.”

Pervasive computing era : 

Pervasive computing era

Mobile computing means more… : 

Mobile computing means more…

Tomorrow… : 

Tomorrow… Pervasive and Mobile Computing Computing is everywhere, invisible, and moving with you WLAN Cellular

Forthcoming applications : 

Forthcoming applications Example: Vehicle Networks transmission of news, road condition, traffic information, weather, music via DAB personal communication using mobile phone networks positioning via GPS local ad-hoc network with vehicles close-by to prevent accidents, report traffic jams, guidance system, etc vehicle data (e.g., from busses, high-speed trains) can be transmitted in advance for maintenance busses, trucks, and trains can transmit logistic information for, e.g., fleet management.

Forthcoming applications : 

Example: Intelligent life System knows your current location, and light turns on as you enter a room, and the seat you are sitting on is adjusted to your size. Your active ID-badge indicates your identity (and your preferences). So brightness can be adjusted also based on your preference. Music will continue when you leave a room and enter another. When you enter a range of 5 km of your home, the air-conditioner will be turned on so you get a cool environment upon arriving home. When you attend MTR, you are automatically connected to a group of people sharing the same interest with you in music, sports, games etc. Forthcoming applications

What’s the future picture? : 

What’s the future picture?

Wireless: Convergence : 

Wireless: Convergence

Pervasive Internet of “Things”… : 

Pervasive Internet of “Things”… The Economist, April 28, 2007

Seamless Mobility : 

Seamless Mobility 1xRTT / GPRS PDA WiFi / 1x / 3G PC GSM / CDMA Mobile Desk Phone PC LAN LAN PBX DSL Laptop PC Headset Home Phone Phone Web Kiosk REMOTE MOBILE OFFICE HOME Corporate fixed / mobile Communications PSTN MOBILITY IP User Mobility Device Mobility Network Mobility PC WLAN Mobile / PDA (eg. P900) Work is something you do, not somewhere you go

Challenges of mobile computing : 

Challenges of mobile computing Where do the challenges come from? Distinct characteristics of mobile and wireless computing: Wireless communications Mobility Mobile devices

Wireless communications : 

Wireless communications Both wired and wireless communications are about transmission of data by the propagation and processing of signals over a transmission medium Data – an abstract entity that conveys meaning or information Signals - electric or electromagnetic representations of data in the physical world Transmission medium - physical path between transmitter and receiver

Wireless communications : 

Wireless communications Transmission medium Guided Media Signals are guided along a solid medium e.g., copper twisted pair, copper coaxial cable, optical fiber Unguided Media Provides means of transmission but does not guide electromagnetic signals Usually referred to as wireless transmission e.g., atmosphere, outer space, water

Wireless communications : 

Wireless communications A wireless communication does not use wires (cables) for communications, but by the transmission of electromagnetic waves through ‘the air’. Michael faraday, James C. Maxwell, Heinrich Hertz Wireless communication has a long history, started in 1896 - Guglielmo Marconi invented the wireless telegraph Advances in wireless technology include radio, television, mobile telephone, communication satellites.

Wireless communications : 

Wireless communications Electromagnetic waves are produced and received via antennas Transmitting antenna - a transmitter delivers radiates alternating current into the surrounding environment in the form of radio or microwave signals Receiving antenna - converts signals from the environment into alternating current and delivers it to the receiver.

Challenges : 

Challenges Wired channel Wired channel can be easily engineered Too many noises? – use shell to protect against electromagnetic noise Large signal attenuation? - use repeaters to amplify the signal Data rate too low? - upgrade to coaxial cable or optical fiber Low error rate - Good quality: 10-6; Optical fiber: 10-11 ~ 10-12 Wireless channel Wireless channel is hardly be engineered High background noises Signal strength fluctuates significantly Low data rate High error rate – Radio: 10-2 or worse

Challenges : 

Wired channel – what if more than one transmitter? Challenges

Challenges : 

Wireless channel – what happens? Challenges

Challenges : 

Wireless channel Low and asymmetric bandwidth High latency High error rate Large variation in available bandwidth Bandwidth differences with orders of magnitude from open-space wireless to indoor wireless Frequent disconnections Network failure is common User’s movement is frequent Shared radio channel Increased security risks Challenges

Mobility : 

Mobility Different entities of mobility Physical / Terminal mobility User mobility Logical mobility

Mobility : 

Mobility Different modes of mobility Personal mobility : reaching a mobile user using a logical identity, irrespective of what device he/she is using, current location in the network, or even which network he/she is located in Session mobility : maintaining access to the same network service / application at different places Service / application mobility : making a service/application available to mobile user when the user has moved to another location with other but similar resources (e.g., print using the nearest printer) – following me service

Challenges : 

Challenges Dynamic change of physical locations Mobile users may use their phones at different places Dynamic change of logical addresses Users may use their laptops to access different networks Frequent change of system configuration Mobile users may use PDAs with cellular networks when outdoor and with WLANs when indoor.

Challenges : 

Location dependency Location management problem: How does the network know where the intended recipient of a message is currently located? Cellular scenario Send broadcast messages from every base station. Challenges

Mobile devices : 

Mobile devices Pagers Cellular phones Portable media players Personal digital assistants (PDAs) Tablet PCs Laptop computers Mobile Internet devices (MIDs)

Challenges : 

Mobile computing devices are becoming smaller, cheaper, more powerful and better integrated Small screen display size No keyboard, only some buttons Small storage capacity Limited computation capability Limited battery power Large variations in design & usage Frequent disconnection & a short life span Challenges

Cope with challenges : 

Need new solutions to old / new problems to overcome the above constraints Need to Reduce communication and operational cost Need to manage mobility Need to conserve energy Need to design special interfaces for small devices Need to enforce wireless security Need to have new computing paradigms asynchronous interactions handling of disconnections adaptation (may need user’s involvement) mobile code and mobile agent Cope with challenges

Cope with challenges : 

The challenges can be tackled in various system components including Mobile devices Mobile wireless networks and protocols Location tracking techniques Mobile computing models, application architectures, and software infrastructure Protocols, OS, and programming languages Application / user requirements, business models Cope with challenges

Topics in mobile computing : 

Topics in mobile computing Wireless communications and networks Modulation techniques, Multiplexing techniques, Medium access control (MAC), Routing, etc. Design of different types of wireless networks Cellular, WLAN, WPAN, WMAN, Satellites Wireless ad hoc networks (WSN, MANET)

Topics in mobile computing : 

Topics in mobile computing Wireless communications and networks Wireless networks can be classified in different ways Short range vs. Long range Infrastructured vs. Ad hoc Heterogeneous

Topics in mobile computing : 

Wireless communications and networks Short-range wireless pertains to networks that are confined to a limited area. Local area networks (LAN): cover corporate building, school campuses, manufacturing plants, homes. Personal area networks (PAN): connect portable computers within close proximity to one another. Operate over unlicensed spectrum reserved for industrial, scientific, medical usage (ISM) No need to obtain a license, and free of charge The most common frequency band is at 2.4 GHz Other bands at 5GHz and 40GHz are also often used. Topics in mobile computing

Topics in mobile computing : 

Wireless communications and networks Long-range wireless networks span large areas - a metropolitan area, a state or province, an entire country, or across world. The goal is to provide wider-area or even global coverage Typically provided by companies that sell the wireless connectivity as a service. Charging either by the minute or by the amount of data transferred. Topics in mobile computing

Topics in mobile computing : 

Wireless communication and networks Infrastructure-based wireless networks mobile computers /devices connect to a wired network via hubs e.g., cellular systems (base station infrastructure) e.g., a laptop access internet via WLAN access points Topics in mobile computing Fixed, wired backbone; Mobiles connect to Access Points.

Topics in mobile computing : 

Wireless communication and networks Ad hoc wireless networks No infrastructure required, temporarily setup a network to meet immediate needs e.g., rescue, home networking, military applications e.g., wireless sensor networks Topics in mobile computing No wired backbone; Peer-to-peer; Multi-hop routes

Topics in mobile computing : 

Wireless communication and networks Heterogeneous networks: integrated network combining different kinds of wireless & wired networks Topics in mobile computing

Topics in mobile computing : 

Wireless networks issues The essential aspects of differrent wireless networks are the same. They share a common foundation in the design of physical layer, median access, network planning and deployment, and network operation. Topics in mobile computing

Topics in mobile computing : 

Mobile computing models Mobile C/S Models Simple C/S model, Client/Agent/Server model, Client/Intercept/Server model Mobile Peer-to-Peer Model Mobile hosts plays the same role and cooperate to Discover peers and resources Route query requests Perform specified tasks Mobile Agent Model Code mobility (with computation, data, and state) Autonomous and Asynchronous Topics in mobile computing

Topics in mobile computing : 

Mobile C/S model C/S model can still be used in mobile environment - mobile hosts act as the clients requesting service from server located at fixed network. However, mobile C/S model deviates from the C/S model used for distributed system in several ways. Mobile C/S model cannot assume continuous network connectivity and powerful client ability RPC (Remote process control) is not suitable due to disconnection; Direct message exchange is not good neither due to weak connectivity and slow network. Need to decouple the communication in synchronous RPC; Use indirection with messages queued at the two ends. Topics in mobile computing

Topics in mobile computing : 

Mobile C/S model No clear division of functionality between mobile client and server at the fixed network Resource limitation on mobile client justifies moving client activities to server side (“thin client”); However, client can not be too “thin”, since disconnection and low bandwidth force us to place some processing ability on client for disconnected operations (“smart client”) Need synchronization between client and server Topics in mobile computing

Topics in mobile computing : 

Mobile C/S issues Optimization Data compressing / filtering Mobile date management Data dissemination and broadcast Caching and invalidation Disconnected operations Location based services Context-aware adaptation Topics in mobile computing

Topics in mobile computing : 

Mobile P2P model No central server, actually no difference between client and server: All nodes have the same role, serving as both server and client Relying on collaboration Completely decentralized & asynchronous operations Nodes can communicate with each other directly Topics in mobile computing

Topics in mobile computing : 

Mobile P2P applications Data sharing and dissemination Instant messaging Collaboration Entertainment (e.g., gaming) … Topics in mobile computing

Topics in mobile computing : 

Mobile P2P features Good programming model for ad hoc network Good architecture for cooperative applications Server side can also move: more flexible Good system scalability Both sides need resource rich devices Complexity in protocol design Topics in mobile computing

Topics in mobile computing : 

Mobile P2P issues Rapid mutual peer discovery and connection establishment Message routing between peers Data sharing among peers Searching / discovery (routing of queries) Caching and invalidation Security Topics in mobile computing

Topics in mobile computing : 

Mobile agent (MA) model A MA is a “process on the move” – dispatched by one host, encapsulating a thread of execution along with a package of code, data, and execution state Executes at a host for a while, halts execution, dispatches itself to another host, and resumes execution there - all under its own control Topics in mobile computing

Topics in mobile computing : 

Mobile agent features Mobility Actively travels across the network, carrying partial / intermediate results calculated at the previous host Not just alternative to message passing; can perform additional tasks along its way of traveling Autonomous Decides by itself what to do and how, when and where it ought to move Asynchrony Mobile agents and users can execute at the same time without blocking each other Topics in mobile computing

Topics in mobile computing : 

Mobile agent advantages Reducing remote communication Perform tasks locally: save network bandwidth Intermediate result data is processed locally rather than transferred back and forth over the network Go to the data if the data can’t come to you Topics in mobile computing

Slide 65: 

MA model of service providing

Topics in mobile computing : 

Mobile agent advantages Overcome message passing latency Local, “instant” interaction with the other party Latest up-to-date information Be adaptive Can encapsulate policies and protocols Topics in mobile computing

Topics in mobile computing : 

Mobile agent advantages Support disconnected/intermittent connectivity, slow network. Support disconnected/weak connectivity operation Topics in mobile computing

Topics in mobile computing : 

Mobile agent applications Especially good for those mobile computing applications Require long connection time and/or user has bad connection/highly mobility User can disconnect and do something else while mobile agent performing tasks over the network E.g., information search, retrieval, filtering, E-commerce, network management, etc. Topics in mobile computing

Mobile agent applications : 

Mobile agent applications Site B Site A Site C Site D Dispatch Computing Computing Computing Computing Site E Receive Topics in mobile computing

Topics in mobile computing : 

Site B Site A Site C Site D Dispatch Computing Computing Computing Computing Site E collaborating Topics in mobile computing Mobile agent applications

Topics in mobile computing : 

Mobile agent issues Need powerful mobile devices if need to have mobile agent platform installed on devices Fault tolerance Security issue is the main obstacle Topics in mobile computing

Topics in mobile computing : 

Mobility management Types of mobility management Handoff management Location management Mobility management in cellular networks Mobility management in Mobile IP Location services in MANET Topics in mobile computing

Topics in mobile computing : 

Topics in mobile computing Protocols / algorithms for resource-constrained mobile environments MAC protocols Routing protocols Clustering Synchronization Data dissemination Data aggregation

Topics in mobile computing : 

Location based services Mobile positioning techniques Cellular phone positioning Network-based vs Handset based solutions GPS WLAN positioning Other technologies (in-door, road beacon, identity) Location-based services GIS LBS architecture Topics in mobile computing

Topics in mobile computing : 

Mobile computing middleware Service discovery in mobile computing Security in mobile computing Reliability in mobile computing Topics in mobile computing

Related journal & conferences : 

Related journal & conferences IEEE Transactions on Communications IEEE Transactions on Parallel and Distributed Systems IEEE/ACM Transactions on Networking IEEE Transactions on Vehicular Technology IEEE Transactions on Computers Transactions on Mobile Computing Mobile Networks & Applications IEEE Communications Magazine Mobile Computing and Communications Review Proceedings of the MOBICOM Proceedings of the MOBIHOC Proceedings of the INFOCOM Proceedings of the GLOBECOM Proceedings of the Vehicular Technology Conference Proceedings of ICDCS …

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