Ubi. Com Book Slides Chapter 7 Context-Aware Systems (Part A: Contexts & the Context-Aware Lifecycle) Stefan Poslad http: //www. eecs. qmul. ac. uk/people/stefan/ubicom Ubiquitous computing: smart devices, environments and interaction 1
Chapter 7: Overview Chapter 7 focuses on: • Internal system properties: context-awareness • External interaction with any type of environment – Focussing more on physical environment – A lesser extent focussing on ICT environment Ubiquitous computing: smart devices, environments and interaction 2
Related Chapter Links • Context-awareness of human environment (i. HCI) and person-awareness and user context acquisition (Chapter 5) • Environment context acquisition: sensors (Chapter 6) • Environment context control: controllers (Chapter 6) • Event-based system models for context-awareness (Chapter 3) • Goal-based models & sequential environment models (Chapter 8) • Content adaptation for mobile terminals (Chapter 4) • UI techniques adapted for use in small and large displays discussed (Chapter 5) Ubiquitous computing: smart devices, environments and interaction 3
Chapter 7: Overview The slides for this chapter are also expanded and split into several parts in the full pack • Part A: Contexts & the Context-Aware Lifecycle • Part B: Context Adaptation Design • Part C: Spatial Awareness 1 • Part C: Spatial Awareness 2 • Part E: Mobile Awareness • Part F: Temporal Awareness & Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 4
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 5
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Context Aware System versus Sensorbased System Ubiquitous computing: smart devices, environments and interaction 7
Contexts • A context represents the state or situation in the environment of a system that affects that system’s (application specific) behaviour • There are many definitions of context • There are several dimensions or properties to characterise contexts • There are many definitions of how to make systems aware of changes in their context: context awareness • Context-awareness is considered to be one of the fundamental properties of Ubi. Comp systems and is a key property of smart environments. Ubiquitous computing: smart devices, environments and interaction 8
Defining Contexts: Concrete In terms of membership of some set of contexts • Location, identities of nearby people, objects and changes to those objects • Applications • External environment: physical, human, virtual – Awareness of internal (self) context may also be useful • What, who, where, when, how it is accessed and why, context is useful (Morse et al. (2000) Ubiquitous computing: smart devices, environments and interaction 9
Context Types: By Application • We can classify context-awareness in terms of types of applications? • Mobility context-aware • Location aware • Time aware Ubiquitous computing: smart devices, environments and interaction 10
Lecture Outline • • Types of Context & Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 11
Life-cycle for Context Awareness • • • Capture Physical Context Capture User Context Processing Adapt to Context Manage contexts Ubiquitous computing: smart devices, environments and interaction 12
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User Context Creation • Acquisition of user context: this can be derived from user’s application tasks • Policy creation: created from user’s tasks to determine how a user context is mediated by environment contexts • Encapsulation and abstraction: of the user context • Sharing the user context so that it can be distributed and accessed. Ubiquitous computing: smart devices, environments and interaction 14
Environment Context Creation / Capture • Acquisition: • Encapsulation: • Abstraction: • Filtering: • Sharing: Ubiquitous computing: smart devices, environments and interaction 15
Context Processing N. B Context acquisition may involve some context preprocessing, here the focus is on context post-processing. Context post-processing enables: • Context-composition: • Context Mediation: • Context Adaptation: Ubiquitous computing: smart devices, environments and interaction 16
Context Composition: Motivation Context composition may also be driven by the need to: • Improve acquisition accuracy for the context – • Improve filtering and adaptation of content • Composite contexts are in inherent an application Ubiquitous computing: smart devices, environments and interaction 17
Context Composition: Challenges • • • Handling heterogeneity of representation Handling heterogeneity of meaning Mediating and coordinating context aggregation Ordering the adaptation to individual contexts Different weightings for combining contexts Handling uncertainty in combining contexts Ubiquitous computing: smart devices, environments and interaction 18
Context Composition, Heterogeneous Contexts & Interoperability Context-aware systems may depend on & combine: • multiple representations for a single context • . • multiple representations of multiple contexts • Multiple representations determined independently by different applications & users Ubiquitous computing: smart devices, environments and interaction 19
Context Composition, Heterogeneous Contexts & Interoperability • Determination of a proposed joint context for meeting can be complex – • Challenge here: to harmonize or standardize annotation so that they would be consistent used by all users. • Security, e. g. , access control could be useful in certain applications to protect privacy or to limit access, – Ubiquitous computing: smart devices, environments and interaction 20
Context Management • Discovery: directory services enable context sources, stores and users to be registered and discovered. • Storage: of context data into some data resource, may include – … • Sharing of environment and goal contexts • Access control: –. Ubiquitous computing: smart devices, environments and interaction 21
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 22
Context Adaptation: Passive vs Active • Passive context adaptation system – Context is presented to users – Context-based tagging (chapter 6) – System is not active in terms of adapting • Active context-adaptation system – Adaptation to context performed by the Ubi. Com system, not human users. • Hybrid context adaptive system – Human user guides or corrects the automatic adaptation Ubiquitous computing: smart devices, environments and interaction 23
Context Adaptation Models Event-based Models (Chapter 3) • Context-awareness links context producer to a contextconsumer or context-adapter • EDA is also similar to a Reactive intelligent system – See Chapter 8 • How do we limit the types of interest? Goal-based Models • Use a (planned) application or user goal to limit the set of current contexts which are useful • Relation of current context to goal context is fundamental Ubiquitous computing: smart devices, environments and interaction 24
Context-aware Application: Location (context) awareness • Goal context • Current context • Context Path • Constraints • Travel to the destination location • Current location • Planned path from the current to destination location • Not to deviate too far from the anticipated or planned position context; Ubiquitous computing: smart devices, environments and interaction 25
Context-aware Application: Location (context) awareness Ubiquitous computing: smart devices, environments and interaction 26
Context Aware Design Issues • • Context Representation Use of Current versus Past Contexts Context Determination Static versus Dynamic CA Active versus Passive Context Adaptation (done) Heterogeneous Contexts & Interoperability Context Composition Ubiquitous computing: smart devices, environments and interaction 27
Context Representations • • • What type of data structures should be used to model contexts? Key-Value pairs Hierarchies / Markup Schemes, e. g. , XML Graphs Object Oriented (o-o) Logic Based: support reasoning about context Strong Ontology Which of these is best? Why? Ubiquitous computing: smart devices, environments and interaction 28
Use of Current Context vs. use of Context History • Simplest type of context-aware system – Uses the current context, the current state, episodic, environment – Operates in an environment that is fully observed and deterministic • But context history can also be used • See Chapter 8 for more in-depth treatment of environments Ubiquitous computing: smart devices, environments and interaction 29
CA Design issues: Context Determination • Context determination: acquisition, accuracy particularly of user context can be complex • Active versus passive context acquisition • Single shot (static) versus dynamic acquisition • Heterogeneous context representation (syntax) and semantics, interoperability • Context distribution: Local context producer but remote context consumer Ubiquitous computing: smart devices, environments and interaction 30
User Context Determination 4 approaches • Combine several low-level sensor inputs to better infer user context, • Can Query user profile or model: abstraction that characterises the user, preferences the user expresses, • Ask users to define their own context. • Observing user interaction Ubiquitous computing: smart devices, environments and interaction 31
Static versus Dynamic CA • Static environment context • Dynamic environment context: Ubiquitous computing: smart devices, environments and interaction 32
Context Adaptation Benefits • Many useful Applications: – • Reduces information overload on users • Lessen cognitive load on users • Filter information to fit a mobile device's limited and physically moving display, – • Disabled people – • Improve Regulation & Control Ubiquitous computing: smart devices, environments and interaction 33
Context-awareness: Challenges • 1. User Contexts may be incorrectly, incompletely, imprecisely determined or predicted, ambiguous • 2. Environment Contexts may be incorrectly, incompletely, imprecisely defined, determined or predicted. • 3. Contexts may exhibits a range of spatial-temporal characteristics • 4. Contexts may have alternative representations • 5. Contexts may be distributed and partitioned, composed of multiple parts that are highly interrelated • 6. Contexts may generate data huge volumes • 7. Context sources and local processes often need to embedded in a low resource infrastructure • 8. Context use can reduce the privacy of humans • 9. Awareness of context shifts can distract users Ubiquitous computing: smart devices, environments and interaction 34
Lecture Outline • • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 35
Spatial-Awareness Overview 1. 2. 3. 4. Trigger spatial-aware services Sense / determine current Location Determine the spatial context Service adaptation: adapt spatial information view w. r. t. to location Ubiquitous computing: smart devices, environments and interaction 36
Spatial-Aware Applications which trigger use of spatial aware • Navigation, e. g. , I'm lost, where is nearest Metro station? • Notification of context change: e. g. traffic queue ahead, change route. . • Querying location context, e. g. What speed limit on this road? • Personal Emergency: e. g. medical and Roadside • Emergency Service Operations: e. g. , Are flammables nearby? • Enterprise Asset Tracking: e. g. “Where is water supply? • Public Asset Tracking e. g. where is the train now? • Personal Asset Tracking e. g. I lost my PDA, where is it now? • Location / time based offers, e. g. Free mobile phone calls while you are in location X • Location & time synchronisation: e. g. , Ima. Hima users Ubiquitous computing: smart devices, environments and interaction 37
Location-Aware vs Spatial Aware vs Composite Spatial Aware Triggering • Awareness of a location – a point in 3 D space • Awareness of a location in relation to another location • Awareness of a location in relating to its surrounding 2 D space • Composite spatial awareness Ubiquitous computing: smart devices, environments and interaction 38
Location Determination Methods Several common Methods • Proximity Analysis • Triangulation • Time Difference of Arrival (TDOA), Multi-lateration • Trilateration • Received Signal Strength (RSS) Ubiquitous computing: smart devices, environments and interaction 39
Location Determination : Triangulation If distance AB, angles at A and B are known then X and Y can be determined using basic trigonometry Sin A = Y / a Sin B = Y / b Y = a * Sin A = b * Sin B Cos A = X / a X = a * Cos A = AB – b * Cos B Ubiquitous computing: smart devices, environments and interaction 40
Location determination: TDOA • Time Difference of Arrival (TDOA), Multilateration • TOA measurement of time signal sent vs. time received: distance d = time t * signal propagation speed s. – N. B. Assumes accurate clock synchronisation, sender knows time of transmission • TDOA or measurement at 2 or more receivers (or sent from 2 or more senders) – use to estimate the difference in distances between the 2. Ubiquitous computing: smart devices, environments and interaction 41
Location Determination: Trilateration • • Trilateration: uses absolute measurements of time-ofarrival from three or more sites Trilateration is a method of determining the relative positions of objects using the geometry of triangles in a similar fashion as triangulation. Ubiquitous computing: smart devices, environments and interaction 42
Location determination: Trilateration 3 Equations to determine location of point O w. r. t. known locations A, B, and C on a 2 D plane RA 2 = X 2 +Y 2 RB 2 = (X-(AO+OB))2 +Y 2 RC 2 = (X-AO)2 +(Y-OC)2 Use substitution to get X and Y X = (RA 2 - RB 2 + (AO+OB)2 ) / 2 (AO+OB) Y = (RA 2 - RC 2 + AO 2+OC 2 ) / 2 OC) – AOX / OC Ubiquitous computing: smart devices, environments and interaction 43
Location Determination: RSS • Received Signal Strength (RSS) Estimate the RF signal strength at a receiver • Knowing the transmission signal strength • Knowing the attenuation of the signal as a function of distance and signal transmission strength, – e. g. , 1/r 2 Ubiquitous computing: smart devices, environments and interaction 44
Location Determination: Range • IR / Blue. Tooth: ? • RFID systems: ? • WLAN: ? • GPS: ? • GSM: ? Ubiquitous computing: smart devices, environments and interaction 45
Location Determination: Uncertainty • Distance & timing measurements has some uncertainty in practice: – – – • variable attenuation (due to moisture in air etc), multi-path effects, reflections, spot interference, knowing the time of transmission accurately etc (see also Chapter 11) How can we correct for this uncertainty? – We can measure signal w. r. t to multiple transmitters to correct for this variability Ubiquitous computing: smart devices, environments and interaction 46
Location Determination: Handling Inaccuracy & Uncertainty • Handling the lack of accuracy, uncertainty in the location • Accuracy requirements for some applications can be relaxed • Could use orientation or a priori knowledge of geoattributes to help determine the location, –. • Can use hybrid systems or assisted systems that combine strengths and minimise weaknesses of several systems. Ubiquitous computing: smart devices, environments and interaction 47
Location & Other Spatial Abstractions • Location coordinate in itself is often not so useful, it is too low-level • It is the Spatial context for a location that is useful and gives it the location meaning. – E. g. , • Forward-tracking: relation of the current coordination to an end coordination / future goal – e. g. , • Backward tracking: relation of current location coordination to start coordination, to past routes, to past goals Ubiquitous computing: smart devices, environments and interaction 48
Location Awareness: Geographical Information System (GIS) • Need spatial services to determine the spatial context – • This is a GIS service • A GIS service needs to do more answer spatial queries, it also needs to be: Ubiquitous computing: smart devices, environments and interaction 49
Location Awareness: Geographical Information System (GIS) A GIS system supports services to support: • Spatial context representations • Spatial context capture • Spatial annotation: bind context to geometric object or view • Coordinate transformation • Spatial data storage • Spatial analysis including queries • Spatial data output & cartography Ubiquitous computing: smart devices, environments and interaction 50
Geospatial Information System (GIS) • A service, such as a Geospatial Information System (GIS) service, is needed to answer spatial queries – E. g. , “Is there a type of service X within 1 km of here? ”. • GIS services represent real world objects – such as roads, land use, elevation with digitised spatial data. Ubiquitous computing: smart devices, environments and interaction 51
GIS: What the Data Represents Geospatial data consists of multiple parts: • Geometrical object – e. g. , point, line, polygon etc • Geo-attributes that form the spatial context – e. g. , – types of feature, and associated attributes, e. g – Annotations of geometrical object Ubiquitous computing: smart devices, environments and interaction 52
GIS: Data Representation • GIS represents real world objects (roads, land use, elevation) with digitised spatial data • Real world spatial objects can be – discrete objects (house) – continuous fields (rain fall, elevation) • Digitised GIS data consists of two parts – Geometrical objects – Spatial context / Geo-attributes
GIS: Geometric Data Capture There a variety of methods used to capture Geo-context • Digitizer – e. g. , • Scanner – e. g. , . • Direct entry of surveyed or sensed data – E. g. , , • Photo interpretation of aerial photographs. – E. g. , Can configure relative location accuracy vs. absolute accuracy & level of accuracy. Ubiquitous computing: smart devices, environments and interaction 54
GIS: Spatial Context Capture • Geocoding: derive location from spatial context – • Reverse geocoding : derive spatial context from location – Ubiquitous computing: smart devices, environments and interaction 55
GIS Data Capture: Processing Geo Data after capture usually requires editing • Vector data must be made "topologically correct" before it can be used for some advanced analysis. – Projections – Adjacency • To remove errors – E. g. , Ubiquitous computing: smart devices, environments and interaction 56
GIS data coordinate Transformation • 100+ different coordinate systems exist for positions • Likely that measured location co-ordinates & geospatial object coordinates in GIS will be different -> Need transformations • Ubiquitous computing: smart devices, environments and interaction 57
GIS Data Storage & Retrieval • '; • Many DBs with spatial extensions use GIS data structures that are based on the Open GIS Consortium (OGC) Geographical Markup Language (GML) standards • Spatial databases are optimised? – Ubiquitous computing: smart devices, environments and interaction 58
GIS: Spatial Queries • Example query, How far, as the crow flies, from Queen Mary to Mile End Tube? SELECT (orig. buildingloc<->dest. buildinglloc)*37. 5 AS "Distance (kms)" FROM buildingl orig, buildingl dest WHERE orig. buildinglname = ‘Queens Building' AND dest. buildingname = ‘Mile. End Tube Station • A spatial query involves determining – which indexed region a spatial object of interest is in where a region bounds a set of spatial objects – then locating a specific object within that selected region, – e. g. , determining the distance from Queen Mary (Object D) to Mile. End Tube station (Object A) Ubiquitous computing: smart devices, environments and interaction 59
GIS: Spatial Queries Ubiquitous computing: smart devices, environments and interaction 60
Spatial Adaptation: GIS Data output & Cartography • Some main uses of spatial-adaptation: – ? ? • Cartography is the design and production of maps, or visual representations of spatial data. • The vast majority of modern cartography is done with the help of computers, usually using a GIS. Most GIS software gives the user substantial control over the appearance of the data Ubiquitous computing: smart devices, environments and interaction 61
GIS Data Output & Cartography Cartographic work serves two major functions: • It produces maps and other graphics, – • To allow the map to be annotated with symbols and text for the information of interest, • Web Map Servers facilitate the exchange of generated maps information via Web Services, – e. g. , ? ? ? Ubiquitous computing: smart devices, environments and interaction 62
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 63
Context awareness: Indoor Call Routing For Mobile Users • Active Badge Location System of Want et al. begun in 1989 • Location awareness users to route calls through to their nearest fixed line phone indoors • Readers detect signals from wearable active badges – Ubiquitous computing: smart devices, environments and interaction 64
Mobile User (ICT) Context awareness: WAN Call Routing For Mobile Users • Basic mobile phone location determination …. • Determine which mobile phone transmitter, its area of operation (its cell), phone is nearest to. • Phone users registered in HLR • When users pass between areas, a cell notifies its VLR • When a call is made by user B to user A, the call first queries the VLR • If A not there, call is made to A’s HLR • Ubiquitous computing: smart devices, environments and interaction 65
Location Determination in A Mobile Phone Network Ubiquitous computing: smart devices, environments and interaction 66
Context awareness: Call Routing For Mobile Users • System is aware of users’ location • Location awareness is a means not the end goal • Interoperability between mobile terminals / handsets and network? • Multimedia content adaption: content to fit resources of limited resource terminal and terminal access network – See later, also Chapter 11, • How to prevent huge choice and volumes overloading mobile user with limited attention capability? Ubiquitous computing: smart devices, environments and interaction 67
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 68
Content Adaptation for Mobile Terminals Content adaptation to two main types of ICT are considered here: • Adaption to the terminal • Adaption to the network connecting the terminal Ubiquitous computing: smart devices, environments and interaction 69
Content Adaptation for Mobile Terminals • UI facilitates presenting and entering information for human use • Universal content access entails content access via a proliferation of interactive devices with diverse capabilities. – Ubiquitous computing: smart devices, environments and interaction 70
UI Context Representation • The UI context can be defined in a UI device profile. • There are several different specifications for representing the UI profile. Ubiquitous computing: smart devices, environments and interaction 71
Content Adaptation • Needed to adapt content for display • Much content designed for decimetre sized screens: – But what if displayed on small displays? e. . g, mobile phone – But what if displayed on large screens? e. g. , projectors, • Need Content adaptation this involves: – Transformation of the created content representation to a different one used in the access device, – Adaptation of the (multimodal) interaction – Adaptation to use a particular device display convention – Adaptation of the content itself. • See also the range of UI techniques adapted for use in small and large displays (Chapter 5) Ubiquitous computing: smart devices, environments and interaction 72
Content Adaptation: Network-Aware • A service that is aware of the characteristics of the physical network is called underlay-network aware (Chapter 11) – • Enhancements are needed to TCP/IP network design to support more flexible context-aware Qo. S delivery. Ubiquitous computing: smart devices, environments and interaction 73
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 74
Temporal Awareness: Time • Time may be modelled as a period – • Time may be modelled as an instant, – • Time can be modelled as a linear sequence Ubiquitous computing: smart devices, environments and interaction 75
Time Awareness: Scheduling Given: • a set of tasks to perform (the user context), • a set of resources to use and • a set of time constraints (the temporal context), The objective of task scheduling is to allocate times and resources to user tasks. Ubiquitous computing: smart devices, environments and interaction 76
Time Awareness: Scheduling • Task scheduling is simplest when … – • Simple scheduling can involve deriving a personalised schedule that it a subset of another schedule known a priori, – e. g. , . Ubiquitous computing: smart devices, environments and interaction 77
Time Awareness: Scheduling Simple job scheduling algorithm is to partial order n tasks in a graph and to search it to find a path Ubiquitous computing: smart devices, environments and interaction 78
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 79
Composite Context Awareness for Mobile Users Mobility context awareness is a good example of composite context adaptation. • Spatial awareness is used to adapt activities with respect to their locality. • Information retrieval from remote sources can be personalised to users’ preferences. • ICT context-awareness is useful for mobile users so that it adapts remotely accessed content so that it fits better the characteristics of mobile access devices and better fits the bandwidth available in the local wireless access loop. Ubiquitous computing: smart devices, environments and interaction 80
Composite Context Awareness for Mobile Users: Applications • Navigation • Automatic annotation of local recordings in the field • Filtered content for mobile users w. r. t. • But what order to do the individual context adaptation in? Ubiquitous computing: smart devices, environments and interaction 81
Context Composition Example: CRUMPET Project System Ubiquitous computing: smart devices, environments and interaction 82
CRUMPET Project System • CRUMPET, Creation of User-friendly Mobile services PErsonalised for Tourism, EU FP 5 Project system is an example of a composite context adaptation application. • In this system, tourism information services such as maps, routes and sight recommendations can be adapted to a spatial context that pertains to the current location, the personal context of a service uses, the network context and the terminal context, Ubiquitous computing: smart devices, environments and interaction 83
The CRUMPE T System Ubiquitous computing: smart devices, environments and interaction 84
CRUMPET Multi-Agent System Architecture Ubiquitous computing: smart devices, environments and interaction 85
Composite Context Awareness: CRUMPET System • Particular ordering of context-aware adaptation follows. • Users’ access terminal profile of memory & display capabilities is exchanged with system during session start Localisation is for example used twice • Current position of a user can be used to constrain a user's request and to further filter the relevant information. • Unless the relevant location is specified explicitly, user gets information relevant for his or her current spatial context. • user’s movements within region can indicate their interests. – E. g. , a user visits a number of old churches, then he or she is probably interested in churches and perhaps also other historic buildings in this town, like an old city hall. Ubiquitous computing: smart devices, environments and interaction 86
Composite Context Awareness: CRUMPET System • Users generate a lot of potential events of interest as they move. • These can be exploited for user modelling & to detect & anticipate relevant user interests. • Hence, the combined location and personal model context can be used to such as get me a map of things of interest at a location. • This is an example of environment context composition in which one type of context (location) may be used to determine another type of context (personal preferences) based upon a user context policy. • Finally, the network profile based upon monitoring the performance of the local mobile terminal to access node, the content, e. g. , a personalised, location-aware map is adapted to the terminal and network profile respectively. Ubiquitous computing: smart devices, environments and interaction 87
Composite Context Awareness: • Note the context composition challenges (Revision from Chapter 5 slide set a ) • Handling heterogeneity of representation • Handling heterogeneity of meaning • Mediating and coordinating context aggregation • Ordering the adaptation to individual contexts • Different weightings for combining contexts • Handling uncertainty in combining contexts Ubiquitous computing: smart devices, environments and interaction 88
CRUMPET System Screenshots Ubiquitous computing: smart devices, environments and interaction 89
CRUMPET System Screenshots Ubiquitous computing: smart devices, environments and interaction 90
CRUMPET System: Fat-client Architecture This deployment architecture has a larger client-side Footprint and is suitable for deploying in high end PDAs and PCs Ubiquitous computing: smart devices, environments and interaction 91
CRUMPET System: Thin-Client Architecture This deployment architecture has a very small client-side footprint and is suitable for deploying in low end PDAs and suitably equipped mobile 'phones Ubiquitous computing: smart devices, environments and interaction 92
Lecture Outline • • Types of Context and Context Properties Context Aware Life Cycle Context Adaptation Spatial-Awareness Mobile User Context Awareness: Call Routing Content Adaptation for Mobile Terminals Temporal awareness Composite Context Awareness Ubiquitous computing: smart devices, environments and interaction 93
Revision For each chapter • See book web-site for chapter summaries, references, resources etc. • Identify new terms & concepts • Apply new terms and concepts: define, use in old and new situations & problems • Debate problems, challenges and solutions • See Chapter exercises on web-site Ubiquitous computing: smart devices, environments and interaction 94
Exercises: Define New Concepts • Context-awareness Ubiquitous computing: smart devices, environments and interaction 95
Exercise: Applying New Concepts Ubiquitous computing: smart devices, environments and interaction 96
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