Research and Latest Trends in Mobile Computing

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© Tata Consultancy Services ltd. June 8, 2022 1 Research and Latest Trends in Mobile Computing Mobile Computing with Recent trends and Future Challenges TCET-ISTE 22 nd July 2006 Vijay T. Raisinghani slides available on http://www.it.iitb.ac.in/~rvijay

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Research and Latest Trends in Mobile Computing. Mobile Computing with Recent trends and Future Challenges TCET-ISTE 22 nd July 2006 Vijay T. Raisinghani slides available on http://www.it.iitb.ac.in/~rvijay. Mobile Computing. Two word definition in itself: computing while mobile - PowerPoint PPT Presentation

Transcript of Research and Latest Trends in Mobile Computing

Page 1: Research and Latest Trends in  Mobile Computing

© Tata Consultancy Services ltd. April 22, 2023 1

Research and Latest Trendsin

Mobile ComputingMobile Computing with Recent trends and Future ChallengesTCET-ISTE

22nd July 2006

Vijay T. Raisinghanislides available on http://www.it.iitb.ac.in/~rvijay

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Mobile Computing

Two word definition in itself: computing while mobile Could be wireless or even wired

Laptop connection over WiFi or Ethernet Application could be local on the device or connecting to server over

network Mobile computing becoming synonymous with wireless mobile

computing Key characteristics

Low device resources (interface, display, memory, battery, CPU) Disconnected operation Wrt Wireless

Low / varying bandwidth (compared to wire-line) Handoffs/changing servers Disconnections

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Latest trends in Mobile Computing

Converged devices (communication, consumer electronics, computing) Phone, Radio/TV, Camera, PC – all in one

Seamless mobility Mobility across heterogeneous wireless networks (WiFi GSM)

Device operating systems Moving towards Linux from Symbian and Windows CE

Motorola has already introduced Linux smart phones BREW (Binary Runtime Environment for Wireless) from Qualcomm

Device form factor Global Positioning System Built-in sensors

Gait sensors for security Ad-hoc networks M-Commerce

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Latest Trends in Mobile Computing - Examples

Killer Applications Real-time gaming, video telephony, web-browsing, multiplayer

games, streaming video/audio. An example below:

Network WiFi Mesh networks to provide outdoor mobile connectivity WiMAX (802.16): Being rolled out in many countries

802.16e – Mobile WiMAX

Movie PosterWith

Visual Code

Cell phone with camera/code scanner

Server with

video clips

Code

Media clip

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Latest Trends in Mobile Computing – ExamplesBREW

Binary Runtime for Wireless Environment® (BREW™) provides a framework for creating applications on a wide variety of mobile devices

Application examples: Email, IM, navigation (location based), address content sync, games, etc

Product of QUALCOMM Internet Services, a division QUALCOMM Incorporated

BREW applications run on phones on which BREW Application Execution Environment (AEE) is present. AEE is loaded by the manufacturers using the BREW Porting Kit

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BREW (contd.)

BREW is thin and fast Platform sits right on top of chip system software, enabling fast

C/C++ native applications BREW is open

Supports other languages beyond native C/C++, including alternative execution environments such as Java, Extensible Markup Language (XML), and Flash

Source: Qualcomm Inc.

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BREW SDK

Facilitates development of software applications Provides

general development and debugging tools sample applications with source code reference material and user guides phone emulator: lets developers run applications on PC

BREW SDK is available on Qualcomm website free of cost Microsoft VC++ is used as the development enviroment

DLL can be used on emulator ARM compiler used to create mod file for handset

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BREW uiOneTM

Traditional application

Source: uiOne: Developing the core UI, BREW Conference 2005, Qualcomm Inc.

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BREW uiOneTM

uiOne application

Source: uiOne: Developing the core UI, BREW Conference 2005, Qualcomm Inc.

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BREW uiOneTM

Flexible application Layout, etc. defined on the

server UI look and feel can be changed

by changing code on server Enables dynamic user

experience

Source: uiOne: Developing the core UI, BREW Conference 2005, Qualcomm Inc.

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Research in Mobile Computing

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Mobile Computing Example

Wireless mediumWireline

Mobile infrastructure

Data Server

Mobile device

Example Scenario

User

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Selected Mobile Computing Journals/Conferences

Journals IEEE: Transactions on Mobile Computing (TMC) ACM: Mobile Computing and Communications Review (MC2R)

Conferences ACM Mobile Computing and Networking (MobiCom) IEEE Infocom IEEE/ACM Conference on COMmunication System softWAre and

MiddlewaRE (COMSWARE) Asian International Mobile Computing Conference (AMOC)

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Mobile Computing Research Areas – Overview

Wireless mediumWireline

Mobile infrastructure

Data ServerMobile device

User

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Mobile Computing Research – Overlap

Networking and Distributed Systems Fault tolerance

Operating Systems Power management, disconnected operation

Computer Architecture Wearable computers

Software Engineering Dynamic reconfiguration

Human Computer Interaction Context awareness

Security and Privacy Biometric authentication

Sensing and Actuation Location sensing, robotics

Source: Carnegie Mellon, http://www.csd.cs.cmu.edu/research/areas/mopercomp/

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Mobile Computing Research Areas – Summary

User and Mobile Device Interface design, authentication, innovative applications, security,

performance improvement, software defined radio Mobile Infrastructure

Integration and internetworking of wired and wireless systems, support for seamless mobility, quality of service

Modeling Analysis and Simulation Mobile agents Wireless Test beds for Technology evaluation Ad-hoc networks Underwater networks

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Recent Research Papers

MobiCom 2005 Pradeep Kyasanur, Nitin Vaidya (University of Illinois at Urbana-

Champaign, US) In an ad-hoc network scenario they study the impact on

network capacity of the number of channels and number of interfaces on a mobile device

Bhaskaran Raman, Kameswari Chebrolu (IIT Kanpur, IN) 802.11 in long-distance mesh networks being designed/used

for low-cost rural connectivity. They describe a new MAC protocol suited for such networks in terms of efficiency

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Recent Research Papers

IEEE TMC 2006 Ying Cai, et al, (Iowa State, US)

Real-time monitoring of movement of mobile nodes in a region. Performance improvement proposed for lowering communication and processing costs.

Mobile patient monitored using sensor network. Data is transmitted using 3G network.

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Recent Research Papers

Infocom 2006 Srinath Perur, Sridhar Iyer (IIT Bombay)

Reachability in sparse mobile ad-hoc networks. Proposed a new way of deciding how “connected” is a sparse ad-hoc network, by looking at connected node pairs.

Raghuraman Rangarajan, Sridhar Iyer (IIT Bombay) WIND: A tool for capacity-constrained design of multi-tier

wireless networks COMSWARE 2006

Vijay Raisinghani (TCS), Sridhar Iyer (IIT Bombay) Optimized communication stacks for wireless devices

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Recent Research Papers

MC2R Sangheon Pack, et al (Seoul National University, Korea)

Selective neighbor caching scheme for fast handoff in IEEE 802.11 wireless networks: Considering hand-off patterns a mobile node’s context is propagated to selected neighboring access points

Paul Grace, et al (Lancaster, UK) Middleware proposed to enable mobile client to discover

services and interact with them

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Detailed Example:Cross Layer Feedback in Mobile Devices

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Typical Mobile Wireless Network

MWN characteristics High bit error rate of wireless channel Mobility induced disconnections

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Typical Protocol Stack Architecture – Layered

Application

Transport

Network

MAC

Physical

User programs, interface

Connection management, flow/error control (e.g. TCP)

Routing, addressing (e.g. IP)

Error free tx; medium access (e.g. 802.11)

Tx of raw bits (e.g. 802.11)

•Application has very low awareness of physical layer and vice-versa•Layered architecture: Layer n has function specific Service Access Points for layers n-1, n+1

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Layered example: TCP

In wireless networks many packet losses are due to bit errors

TCP on packet loss assumes network congestion reduces throughput TCP’s congestion assumption fails

unaware of wireless physical layer reduction in send window inappropriate

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Cross layer feedback: Motivation

Protocol stack layering useful: software engineering perspective

Strictly layered stacks do not perform well over wireless networks network conditions are highly variable: random errors;

intermittent disconnection mobile nodes are “resource poor” Several assumptions from fixed wired networks do not

hold for wireless: packet losses, disconnections, mobility

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Observation

Cross layer information can help improve performance over wireless networks

Upper to lower layers TCP timer information application QoS requirements user feedback

Lower to upper layers link characteristics network connectivity status

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Some existing approaches

TCP thruput information to tune physical layer power (Chiang. IEEE JSAC, 2005)

ATCP / RWC for TCP (Raisinghani VT, Singh A, Iyer S. IEEE ICPWC, 2002)

TCP QoS information to adapt link layer retransmissions (Chiasserini, Meo. IEEE Globecom, 2001)

Layer2 information to MobileIP for IP handoff (Wu, et al. MONET, 2001 )

TCP fast retransmit (Caceres, Iftode. IEEE JSAC 95)

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Cross Layer Feedback: Optimizing TCP for MWN

Several approaches focus on mitigating Adverse effect of wireless channel Mobility induced disconnections

Any approach involves one or more of: Fixed Host (FH) TCP stack modification Base Station (BS) per-connection support Mobile Host (MH) TCP stack modification

Typically assume TCP sender at the FH

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Our approach: Optimizing TCP for MWN

Modification to TCP stack at MH only Optimizing TCP to mitigate effect of

mobility induced disconnections Focus on TCP sender at Fixed Host (FH) Approach: Use of cross-layer feedback

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User feedback: Motivation

Cross layer feedback has useful optimizations Designed for standard problems: handoff, link layer retx,

etc. Optimizations may not fulfill user needs

User aware of exact self needs User can take better decisions which are contrary to system

behavior Required for improving user experience

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User Feedback

User feedback examples: Impending disconnection information Dynamic changes in application priorities

For example: In view of impending disconnection, an ongoing FTP may become more important than an ongoing video conference; contrary to default system priorities

System can avoid performance degradation by mapping user input to protocol specific actions

E.g. Map user priorities to TCP receiver window of each application on device

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Background: TCP receiver window Reflects receivers available buffer through advertised

window (awnd) in ACKs Optimum awnd = bandwidth*delay (bdp) to fill pipe and

maximize sender throughput awnd < bdp decreases sender throughput Each application on MH may require different awnd,

according to bdp

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Receiver Window Control (RWC)

Exploits idea: Sender throughput decreases as awnd < bdp Higher awnd for high priority applications Restrict awnd for low priority applications

Assume total awnd is a fixed resource (Re)distribute awnd according to priority Results in download bandwidth change for

applications on device

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Cross Layer Feedback: Issues

How to pass layer n information to layer m ? When incorporating feedback from other layers in layer n

How to protect layer n’s correctness, reliability ? How to resolve conflict due to feedback from multiple

layers to layer n? How to pass event information to other layers (interrupt

v/s polling)? How to ensure

maintainability of CLF ? minimum overhead due to CLF ?

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Cross Layer Feedback: “Punch hole” approach

Ad-hoc approach Introduce additional code in

layer for CLFApp

TCP

IP

MAC

Phy

get_handover_info()

Code block

for CLF

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CLF:“Punch hole”

Each additional CLF code block can slow down data path (thruput) of layer

Porting CLF will require rewriting for specific OS

Difficult to control to layer’s correctness since updates by different CLF code blocks

Difficult to disable/ remove code intertwined with regular layer code

Difficult to do fast prototyping/additions since ad-hoc

Multiple event monitors within a layer could slow down data path (thruput) of layer

App

TCP

IP

MAC

Phy

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CLF Architecture

CLF basically stack modification Multiple ad-hoc cross layer modifications can affect

stack's reliability, efficiency, maintainability Design goals for architecture

Efficiency: minimal overheads (e.g. cpu, memory, data path delay); enhanced performance

Minimum intrusion: protect stack correctness; easy to extend / reverse CLF

Portability: easy porting to different systems Rapid prototyping: new CLF idea easy to develop/deploy

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ECLAIR: CLF architecture

Optimizing SubSystem: Cross layer feedback algorithms (protocol optimizer – PO); receive layer events; decide other layers behavior

Tuning Layer: Monitor layer events; API to protocol optimizer; access layer's control data structure values

Minimal CLF code in stack, if required

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ECLAIR details

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ECLAIR: (e.g.)TL APIs

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Linux internals: TCP (for RWC)

sock.h header file.Contains socket and tcp data structure

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ECLAIR implementation (Linux): RWC

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ECLAIR implementation (Linux): RWC (contd…)

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ECLAIR validation

Simulation: no RWC wget: no RWC

•Similar setup; no CLF; equal thruput

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ECLAIR validation

•Similar setup; RWC

Simulation: with RWC wget: ECLAIR RWC

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ECLAIR performance

m applications

n reads

O(m x n)•non-ECLAIR RWC invoked on each read()• read() involves user-kernel crossing

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ECLAIR: Salient features

Event Notification: TLs provide facility for POs to register for interesting events at a layer. E.g. TCP can register for handover events at Mobile-IP layer

Switch on/off: Cross layer system is separate. Can be easily/dynamically switched on or off. Individual POs may be switched on/off

Seamless mobility: through POs that monitor/ control multiple protocol stacks. E.g., seamless mobility PO monitors CDMA (or GPRS) / WLAN interfaces’ signal strength. Algorithm maps signal strength to throughput achievable on interface. PO takes decision to change interface

User Tuning Layer(UTL): UTL allows device user or external entity e.g.: a distributed algorithm or base station, to tune the device behavior

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Related Work

Sudame, Badrinath, MONET 2001 CLF: link conditions; internal ICMP messages / handler Each application defines application/transport layer

adaptation Inouye, Binkley, Walpole, Mobicom 1997

CLF: interface – add/remove, cost, bandwidth Adaptation module(per layer) manages

adaptation/sequential propagation of (a) events (b) policies

Any to any layer CLF / generic architecture/optimizations not discussed

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Future Work

Multiple cross layer interactions could affect protocol correctness Resolve cross layer feedback conflict

Extend ECLAIR for seamless mobility Add components for interaction with network nodes

ECLAIR is good for asynchronous CLF Improve ECLAIR for synchronous CLF

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Thank you

[email protected]@it.iitb.ac.in

http://www.it.iitb.ac.in/~rvijay http://www.it.iitb.ac.in/~sri