CSE 535 Mobile Computing. An Overview of Mobile Computing: Part I Motivation and Challenges

Transcription

1 CSE 535 Mobile Computing An Overview of Mobile Computing: Part I Motivation and Challenges Georgios Varsamopoulos School of Computing and Informatics Arizona State University

2 2 Mobile Computing The need for "information anywhere anytime" has been a driving force for the increasing growth in Web and Internet technology, wireless communication, and portable computing devices. The field of mobile computing is the merger of these advances in computing and communication with the aim of providing seamless and ubiquitous computing environment for mobile users. Mobile computing techniques are essential for enabling distributed and net-centric applications which require remote and ubiquitous information access.

3 3 Mobile Computing Challenges Mobile computing environments severe resource constraints frequent changes in operating conditions. This has led to many new and challenging problems: support for mobility in network protocols, efficient and adaptive resource management techniques for wireless bandwidth and battery power predicting mobility patterns performance modeling and simulation of mobile applications, supporting mobile real-time multimedia applications.

4 4 MC - Fundamentals Mobile Computing Adaptive Computing and Communication Cross-Layer approach is need for Adaptation Conserving resources such as energy Mobile computing is distinct from distributed computing Mobile computing is an essential component of Ubiquitous computing.

5 Mobility and Adaptability Mobile Systems 1. Resource Poor 2. Less Secure 3. Poor Connectivity 4. Less Energy Dynamic Adaptation Application System QoS (re) negotitation Fig: Dynamic Adaptation 5

6 6 Example Adaptive Approaches Approach 1: Combine solutions with different optimality ranges/performance characteristics. Approach 2: Treat change in system state as a transient fault and use the techniques of designing fault-tolerant protocols Approach 3: Dynamically monitor the system state and use the solution which is suitable for the current system state. Many others -.

7 7 Promises of Mobile Computing Global information services at any time from any location Mobile users as integrated consumers and producers of data and information Ubiquitous computing where mobile computers become an integral part of daily activities

8 8 Mobile Applications Expected to create an entire new class of Applications new massive markets in conjunction with the Web Mobile Information Appliances - combining personal computing and consumer electronics Applications: Vertical: vehicle dispatching, tracking, point of sale, information service (yellow pages), Law enforcement Horizontal: mail enabled applications, filtered information provision, collaborative computing

9 9 Vertical Applications l Serve a narrow, niche application domain Services dispatch (taxi, fire, police, trucking) Sales tracking (point of sale, market trends) Mail and package tracking (courier, postal) Relatively easy to implement due to restrictions and assumptions homogeneous MUs limited numbers of users

10 10 Horizontal Applications Broad, domain-independent applications serving a mass-market Electronic Mail and News Yellow Pages Directory Services Multimedia Merchant Catalogs Digital Libraries Location-based Information Filtering Driving force of mobile computing research

11 Call Medical Example Ambulance arrives/departs Closest hospital Access patient records Send vital signs Update patient records Page hospital personnel Order medical supplies

12 12 Party on Friday Update Smart Phone s calendar with guests names. Make a note to order food from Dinner-on-Wheels. Update shopping list based on the guests drinking preferences. Don t forget to swipe that last can of beer s UPS label. The shopping list is always up-todate.

13 13 AutoPC detects a near Supermarket that advertises sales. Party on Friday It accesses the shopping list and your calendar on the Smart Phone. It informs you the soda and beer are on sale, and reminds you. that your next appointment is in 1 hour. There is enough time based on the latest traffic report.

14 14 TGIF Party on Friday Smart Phone reminds you that you need to order food by noon. It downloads the Dinner-on-Wheels menu from the Web on your PC with the guests preferences marked. It sends the shopping list to your CO-OP s PC. Everything will be delivered by the time you get home in the evening.

15 15 Wireless Networks

16 16 Wireless Networks Cellular - GSM (Europe+), TDMA & CDMA (US) FM: Kbps; Digital: Kbps (ISDN-like services) Cellular Subscribers in the United States: 90,000 in 1984; 4.4 million in 1990; 13 million in 1994; 120 million in 2000; million by 2004 (Cahner In-State Group Report). Handheld computer market will grow to $1.77 billion by 2002 Public Packet Radio - Proprietary 19.2 Kbps (raw), 9.6 Kbps (effective) Private and Share Mobile Radio Paging Networks typically one-way communication low receiving power consumption Satellites wide-area coverage (GEOS, MEOS, LEOS) LEOS: 2.4 Kbps (uplink), 4.8Kbps (downlink)

17 17 Wireless Networks (Cont.) Wireless Local Area Networks IEEE Wireless LAN Standard based systems, e.g., Lucent WaveLan. Radio or Infrared frequencies: 1.2 Kbps-15 Mbps Packet Data Networks ARDIS RAM Cellular Digital Packet Data (CDPD) Private Networks Public safety, UPS.

18 18 Wireless Local Area Network Data services: IP packets Coverage Area: Offices, buildings, campuses Roaming: Within deployed systems Internet access: via LAN. Type of services: Data at near LAN speed.

19 19 Wireless Characteristics Variant Connectivity Low bandwidth and reliability Frequent disconnections predictable or sudden Asymmetric Communication Broadcast medium Monetarily expensive Charges per connection or per message/packet Connectivity may be weak, intermittent and expensive

20 20 Portable Information Devices PDAs, Personal Communicators Light, small and durable to be easily carried around dumb terminals [InfoPad, ParcTab projects], palmtops, wristwatch PC/Phone, walkstations run on AA+ /Ni-Cd/Li-Ion batteries may be diskless I/O devices: Mouse is out, Pen is in wireless connection to information networks either infrared or cellular phone specialized HW (for compression/encryption)

21 21 Portability Characteristics Battery power restrictions transmit/receive, disk spinning, display, CPUs, memory consume power Battery lifetime will see very small increase need energy efficient hardware (CPUs, memory) and system software planned disconnections - doze mode Power consumption vs. resource utilization

22 22 Portability Characteristics Resource constraints Mobile computers are resource poor Reduce program size interpret script languages (Mobile Java?) Computation and communication load cannot be distributed equally Small screen sizes Asymmetry between static and mobile computers

23 23 Mobility Characteristics Location changes location management - cost to locate is added to communication Heterogeneity in services bandwidth restrictions and variability Dynamic replication of data data and services follow users Querying data - location-based responses Security and authentication System configuration is no longer static

24 24 What Needs to be Reexamined? Operating systems File systems Database systems Programming Languages Communication architecture and protocols Hardware and architecture Real-Time, multimedia, QoS Security Application requirements and design