Table of Contents
Wireless Services
Key questions
- What service do we want to create?
- For whom do we create the service?
- What kind of devices do they have?
- What are the devices communication capabilities?
- Do we need a client program for user device?
- What is our communication model?
- What is required from user & how can we help on it?
- What can we optimise in the service?
Communication models
- Client server models
- Request-reply
- Push
- Publish-subscribe
- Peer to peer communications
Request-reply
- Client requests data & server provides the data requested
- Most common model
- Latency heavily affected
Push
- Server sends data to client without requests
- Can be intrusive
- Who may push data to mobile devices?
- Push validation, whitelists
- OMA Push Proxy Gateway (OMA PPG)
- Is the communication capability always on at user's device?
- E.g. is Bluetooth communication capability turned on by default?
Publish-subscribe
- Client subscribes itself to server
- Whenever subscribed data in server changes it is pushed to the client
- Advantages over request-reply
- Reduced bandwidth requirements
- Server App only sends data changes for a specific point to clients registered to exception on that point
- Reduces latency problems
- Client App no longer constantly asking for new data
- Data not delayed by polling cycles
Publish-subscribe ...
- How to handle subscriptions
- Server side
- Lost connection → unsubscribe?
- Timers
- Client side
- Automated re-subcriptions
- When to give up?
- Retransmissions?
- Limitations to amount of subscribees?
- Allow anonymity to subscribers?
- Presence based services
P2P
- Communication Apps (devices) are equal
- Either can initiate the connection
- Data transmission can go in both ways
- End-to-end security
- How to handle differences in device capabilities
- Division of calculation
- ComLab - Peerhood project
- P2P neighborhood
- Provides information about devices & their Apps that are within communication range
- Supports multiple communication technologies
- Provides capability to switch between commmunication technologies seamlessly
Ad-hoc
- Spontaneous temporary connections
- All communicating devices can be mobile
- App can not rely on connections remaining functional
- Routing is problematic
- Load balancing
- Movement of nodes may cause extra burden to others
Client
- Is there a need to create one?
- Can the service be used with an existing application
- E.g. microbrowser .. instant messaging client (imo)
- UI
- What kind of interaction has to be supported
- How many hardware platforms have to be supported
- Data storage
- Do you need to store data at the device?
- Can data be stored & how much space is available?
User aspects
- Whats required from the user?
- Creation of connection
- Is the wireless connection creation simple enough?
- Interaction with the service?
- Transparent service
- The service access & running does not require any user action
- E.g. information walls
- Where to draw the line on automation
User apsects ...
- How can we help the user to use the service
- personalisation
- What is too much automation?
- Configuration
- Can the user know when the selections are done?
- Context-Awareness
- Location
- Time
- Role
Optimisation
- What to optimise?
- Minimise data transfer?
- Minimise packet amount/payload?
- Minimise client processor use?
- Security Vs. usability
- Selections depend on requirements of the service & the user
Wireless posibilities
- Mobility
- Presence & availability
- Mobile device is most of the time with user
- Location
- Utilise user's location to customise the service
- Context-Aware application
Architectures
Mobile Internet
- Not just conventional web browsing
- Browsing is cumbersome with mobile devices
- Apps & services
- Transactions
- Connectivity to people
- Games & entertainment
- Sources of media content
- Manage everyday events
Mobile Internet - Specifications
- Architecture specifications
- Permanent baseline of MITA
- Key system specifications
- end-to-end system aspects
- Architecture frameworks
- Define how to handle some special issues e.g. security & QoS
Mobile Internet - Architecture specification
- UI & App framework
- Guidelines for UIs
- Limited set of UI styles
- Mapping App functionality to physical UI in understandable way
- Minimising customer learning curves to adopt new Apps & services
- Interaction models
- Messaging
- Browsing
- Rich Call
Messaging
- Non real-time
- Client-server based communication
- Asynchronous
- Server functionality
- Store & forward (SMS, EMS, MMS)
- Store & retrieve (EMAIL)
- Store & push
- Publish & subscribe
Browsing
- Near real-time
- Request-response
- One-way audio & video streaming capability
- XHTML mobile profile
- Online & offline browsing
Rich call
- Two-way real-time communication
- QoS
- Jitter (variation in time between packets arriving)
- Latency
- Voice & video calls
- Concurent communication
Internet protocols in MITA
- IP protocol extended to support mobility (mobile IP)
- OS & platform support in MITA
- Sets basic requirements for OS & platform
- Defines required functionality
- Libraries, APIs, network protocols, …
- Does not define preferred OS just the required capabilities
- Eases the portability of Apps
- Multiple access in MITA
- Defines the elements needed to allow access from mobile device to IP network
- Access independent interface shields the mobile Internet layer from underlying technology
MITA - Key system specifications
- Naming Numbering & Addressing (NNA)
- Presence
- Reachability
- Location
Naming Numbering & Addressing
- Identity/addressing
- Phone number
- www-address
- E-mail address
- Translation between different types of naming schemes on different communication types
Presence
- Provides dynamic information about
- The status & availability of users & mobile devices
- One user may have multiple App level identities
- Presence can be different for different Apps
Reachability
- Defines how the user/device can be reached through web/mobile domain
- Tries to solve the problem caused by different types of networks
- Access independent connectivity
- Mobility management
- Reliability to end-to-end communications
- Service discovery
- Three types of methods
- SD on ad-hoc networks
- SD on Internet
- SD for presence & virtual community
Location
- Defines software & protocol interfaces for location services
- Device management & data synchronisation
- Distributed applications & databases
- Link between presence & contact/calendar
- Personal Information Management (PIM)
- Content download
- Content formats
- Content adaptation
- To support different types of devices
- Privacy
Architecture frameworks
- Defines how to handle some issues that are complicated to solve without a common & unified model
- Structured under common framework before a more detailed architecture is built
- Current frameworks include:
- Directories
- Security in MITA
- QoS
Directories
- Network repositories about people, places & things
- Schema
- Access methods
- Directory store
Security
- Integrity
- Confidentiality
- Availability
- Authentication
- Authorisation
Mobile Internet interfaces
- Open interfaces to software & protocols for software developers & integrators
- Quality of service
- Real-time, Near real-time, Async, ..
- Jitter, latency, tolerable Delays, …
MITA ppt
Ubicomp & App areas
- Ubiquitous computing - Mark Weiser (1952-1999), Xerox Parc 1988
- Each person is continually interacting with hundreds of nearby interconnected computers without explicitly attending to them
- Computers are integrated in everyday objects like motors.
- people use the items not computers as much as you use a drill not the motor
- “The most profound technologies are those that dissapear. The weave themselves into the fabric of everyday life untill they are indistinguishable from it” - Weiser, The computer of the 21st century, scientific american, september 1991.
- Pervasive computing - Academia, IBM 1999
- Pervasive computing encompasses the dramtically expanding sphere of computers embedded within and instrinsically part of larger devices - IBM
Ubicomp & App areas ...
- Ambient inteligence - European commision
- “People living easily in digital environments in which the electronics are sensitve to peoples needs, personalised to their requirements, anticipatory of their behaviour and responsive to their presence” - philips
- “Ambient inteligence repsents a vision of the future where we shall be surronded by electronic environmnets, sensitive and responsive to people. Ambient intelligence technologies are expected to combine concepts of ubiquitous computing & intelligent systems putting humans in the center of technological development” - 2nd European symposium on ambient intelligence
- Calm computing - Weiser & John Seely Brown 1996
- Computing activity takes place in the background & provides outcome in an unobtrusive way
- Dangling strings, Laughing lily, …
Ubicomp & App areas ...
- Active environments, augmented environments, augmented reality
- Virtual reality takes place in digital world, augmented environments brings digital enhancements in normal environments
- Augmenting humans
- Adding capabilities to humans
- Computing power is everywhere, because computer is embedded in the user
- Awareness
- Communication with environment
- Knowledge of current situation
- Knowledge of users
Challenges
- User interfaces
- Multi-modality
- Modality–> way to convey information between a user & App interface using single distinct human capability to process the information
- Text, graphics, speech, audio, …
- UI adapted to the device capability
- Speaker, graphical display, …?
- Microphone, keyboards, …?
- Connections
- Machine to machine communications?
- Automation
- System control Vs. user control
- Privacy Vs usability
Comlab & ubicomp Apps
- Guidance systems
- Mobile phone & bicycle communications
- Automated locks & computer login
- ME- Mobile Electronic Personality
References
- Mobile Internet Technical Architecture book series, Nokia & IT Press
- Technologies & standardisation
- Solutions & tools
- Visions & implementations
- Ubiquitous computing
- Magazines
- Personal & ubiquitous computing magazine - springer verlag
- IEEE pervaise computing magazine - IEEE
- Books
- Security for ubiquitous computing - Frank Stajano
- Pervasive computing - Technology & architectures of mobile internet applications - Jochen Burkhardt et al.
- World without secrets: Business, crime & privacy in the age of ubiquitous computing - Richard Hunter
References ...
- Conferences
- IEEE international conference on pervasive computing
- Wearcomp
- Important articles
- Weiser M: The computer for the 21st century, scientific american, september 1991
