Introduction to Mobile Computing

1
Introduction to Mobile Computing - Near Future
Communications (NFC)
2
Overview

• Introduction to NFC
• WLAN Amendments
• Smart Antenna
• Cellular systems Handover
• The Next Generation 4G

3
Introduction

• Since the first wireless communication technology
  was introduced over 100 years ago this field has
  constantly been evolving
• This evolution is/was mostly driven by
  technological advances and user demand which has
  resulted in
• Development of new wireless technologies
• Enhancements for existing technologies
• Some of these developments are ...
• Amendments to the original WLANs standard
• The emploment of smart antennas
• New handover strategies to support future
  cellular systems
• The Next Generation of Communication 4G

4
WLAN Amendments

• When WLANs were first developed this technology
  did not really take into consideration a number
  of issues
• Only with time these shortcoming became apparent
  and were addressed
• Since the early days WLANs have constantly been
  evolving through the addition of amendments to
  the original specification that are now defined
  as part of the 802.11 WLAN standard
• To these belong the 802.11n, 802.11s, 802.11u,
  802.11r and 802.11p amendments

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WLAN Amendments

• 802.11n Increased Bandwidth
• Extension to the original WLAN standard to
  support multiplex capabilities for higher
  throughput
• Through the use of multiple transmitter and
  receiver antennas this standard is capable of
  providing data rates up to 50 times faster than
  802.11b and 10 times faster than 802.11a or g
• This is referred to as MIMO (multiple input
  multiple output) and is based on spatial
  multiplexing and a wider range using special
  coding techniques for accessing the air interface
  

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WLAN Amendments

• 802.11s Mesh Networks
• Mesh networks are self-configuring networks that
  allow any nodes that is part of this network to
  relay packets on behalf of other nodes
• By using this approach the network bandwidth is
  increased
• Also adds fault tolerance to networks the failure
  of a single nodes is compensated by other nodes
• Standard defines a protocols and architecture to
  provide mesh network capabilities for WLANs

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WLAN Amendments

• 802.11u Interworking Extension
• standard aims to allow devices such as mobile
  phones using a different wireless standard to
  link up and join a WLAN
• this will enable interworking with external
  networks of a different wireless standard  
• authentication for WLAN access will be based on
  authentication details of external network the
  device belongs to
• this would provide better coverage and
  connectivity for mobile users
• standard still under development - due to be
  published in March 2009  

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WLAN Amendments

• 802.11r Fast Roaming
• although handovers are already supported by the
  current WLAN standards (defined by 802.11f
  standard) these are not fast enough to
  support delay-sensitive applications such as
  voice and video transmissions
• extension to provide fast roaming through
  transition (handovers) between Basic Service Sets
  (BBSs) under different administration
• this is achieved through modifying the transition
  procedure by including bandwidth reservation and
  security requirements prior to transferring to a
  new BSS
• under development - due to be published in April
  2008

9
WLAN Amendments

• 802.11p WAVE
• WAVE stands for Wireless Access for the
  Vehicular Environment to provide wireless
  communications to ambulances and transport
  vehicles such as taxis
• Extension to the 802.11 standard to support
  intelligent transportation systems (ITS) for
  communication between vehicles and roadside
  infrastructure within a specified band
• WAVE is also defined as part of the IEEE 1609
  standard 802.11p is based on this
• Standard is meant for applications such as road
  toll systems
• Under development due to be published by April
  2009

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Smart Antenna

• Traditional antenna technology is usually based
  on a single hardware implemented
  receiver/transmitter with an attached antenna to
  perform the required operations
• This concept is very limited in its capabilites
  and is restricted to simply transmitting and
  receiving signals
• Any other functionality cannot be supported
  although a signal is able to provide further
  details that can be used to derive important
  information
• To this belong the for instance the direction a
  signal is coming from
• New developments in this field are trying to make
  use of this through a variation of standard
  antenna technology which are also known as smart
  antenna

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Smart Antenna

• Smart antenna are an array of antennas that are
  able to determine the direction a signal came
  from and use this information to calculate the
  position of the source of the signal using a
  special signal processing algorithms
• Smart antenna are also referred to as adaptive
  antenna
• This technology is used for radar based tracking
  and scanning, radio astronomy, radio telescopes
  and cellular systems of the 3rd Generation (UMTS)
• The functions a smart antenna system supports can
  be devided into
• Estimation of the direction of arrival (DOA)
• Beamforming

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Smart Antenna

• Estimation of DOA (Wikipedia, 2007)
• In order to determine the direction of arrival of
  a received signal smart antenna use special
  algorithms
• These algorithms are based on finding a spatial
  spectrum of the antenna array, and calculating
  the DOA from the peaks of this spectrum
• Techniques used for determining the DOA are
• Multiple Signal Classification (MUSIC)
• Estimation of Signal Parameters via Rotational
  Invariant Techniques (ESPRIT)
• Matrix Pencil method derivatives

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Smart Antenna

• Beamforming
• Beamforming allows smart antenna to align a
  signal in the direction the device the system is
  communicating with rather than transmitting/receiv
  ing in/from all directions forming a beam
• This is achieve by adjusting parameters that will
  increase the magnitude in the desired direction
  and minimise it in all other directions
• At the same time the pattern of undesired signal
  that could potentially interfere with the
  reception/transmission in this direction are
  nulled
• By using beamforming overall interference in the
  system is greatly reduced

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Smart Antenna

• Types of Smart Antenna
• Switched smart antenna
• The parameters used to create the beams in
  different required directions are predefined
• The transmitter simply switched between the
  different parameter pattern depending on the
  direction the communication is meant to be sent
  out to or received from
• This is ususally based on a received signal
  measurement
• Adaptive smart antenna
• The paramters used to create the beams in
  different directions are adjusted and updated
  adptively in real time
• This techniques allows for more accuracy
  regarding the direction and width of the beam and
  hence results in further reduction in
  interference

15
Cellular Systems Handover

• As cellular systems develop further new
  challenges are placed on algorithms and
  techniques used in traditional systems
• In order to make these suitable for future use
  new techniques need to be developed
• One particular challenge for cellular systems is
  the handover techniques which is of vital
  importance to communication in these type systems
  as it insures the continuity of the connection as
  a mobile moves from one cell to the next
• It has a direct impact on the quality of the
  connection perceived by users

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Cellular Systems Handover

• Traditional handover techniques such as the
  hard and soft handover are based in the
  measurement of the signal(s) sent out by the
  surrounding base stations or the mobile devices
• Based the strength of received signal(s) either
  the system or the mobile device makes a decision
  when and to which base-station to handover to
• As the process of measuring, deciding and
  initiating a handover can be time-consuming
• With cells shrinking in size to accommodate more
  users within the network area covered current
  handover techniques are no longer able to support
  this
• Hence new handover concepts need to be developed
  that are capable of supporting this

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Cellular Systems Handover

• Handover Research
• To make the handover process in future cellular
  systems faster current research is
  concentrating on prediction techniques that allow
  forecasting the future path of a mobile device
• By taking this approach resources in the next
  visited cell can be allocated in advance, the
  likelihood of an ongoing call being dropped
  greatly reduced and the time to handover to the
  next cell be shortened
• Information used to make the prediction can be
  accumulated movement history of individual mobile
  devices or other details that allow drawing
  conclusions regarding future movement

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Cellular Systems Handover

• Handover Research
• Another challenge is represented by the changing
  architectures of 3G systems
• As the cellular structure of 3G systems is able
  to use a hierarchical architecture with
  overlaying cells it is possible to handover not
  only to the next cell but also to a cell below or
  above the cell user is currently residing in

• (Morawek et al., 2000)

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Cellular Systems Handover

• Examples of Handover Research
• Zone-based Handover Concept (Lu et al., 2004)
• This scheme is based on dividing the cell into
  different areas non-handoff, pre-handoff or
  handoff zone
• Depending on which zone a device is in a
  particular action is carried out
• non-handoff zone (center of cell) no action
  handover unlikely
• pre-handoff zone system reserves resources
• handoff zone system prepares for handover to
  new cell
• In order to determine the future visited cell for
  the resource reservation this scheme employs a
  tracking algorithm to track the location,
  direction and speed of travel of a mobile device
  which are check in regular time intervals
• As tracking details change the system updates the
  resource reservation in predicted cells
  accordingly

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Cellular Systems Handover

• Examples of Handover Research
• Shadow Cluster Concept (Levine et al., 1997)
• This concept is aiming at reserving resources for
  potential handovers
• Using real time information on traffic patterns
  and the individual bandwidth requirements of
  mobile devices this scheme creates a zone of
  cells around the cell currently visited by the
  mobile device, which holds reserved resources
• This can be compared to a shadow of cells around
  the current cell with a different amount of
  resources reserved in every one of them depending
  on the systems prediction of future resource
  requirements
• As the mobile device moves the shadow cluster
  follows the device and is updated according to
  the traffic and bandwidth information provided by
  the network

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The Next Generation 4G

• Cellular systems are in a constant state of
  development
• Current efforts are working towards implementing
  3G UMTS systems by 2010 nationwide (this date may
  differ for different countries)
• In the meantime research developments are
  continuing
• While 3G is a technology in its own right which
  is largely incompatible with other wireless
  technologies the next generation is aiming to
  bring together different wired and wireless
  technologies provide wider coverage and
  convenience to mobile users

22
The Next Generation 4G

• Characteristics of 4G Systems
• With the convergence of different technologies 4G
  system will provide bandwidth ranging fron
  100Mpbs to 1Gbps in outdoor and indoor
  environments
• Communications will be IP packet-based providing
  QoS between communication links a high level of
  security
• Frequency range to be allocated for 4G systems is
  above 3GHz
• Due to the new network environment 4G systems
  will be able to provide new applications to users
  such as Game playing, Communication without
  latency

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The Next Generation 4G

• The Handover and 4G
• In 4G systems users will be expected to be able
  to seamlessly move between different networks,
  i.e. Mobile phone to WLAN
• This means that 4G systems will need to support
  handovers algorithms to facilitate this
• This will involve an exchange of information
  between the systems and a way to allow sharing
  user details for authentication etc.
• Currently research in this field is still in the
  early stages
• Further details can be found at
  http//www.4g.co.uk/

24
The Next Generation 4G

• It is said that before 4G will be implemented an
  intermediate step in the evolution of
  communication will happen 3.5G
• http//www.nokia.com/A4126518

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IMWT NFC
Questions ...?
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References

• Morawek, Roman Öczelik, Hüseyin (2000) UMTS
• basic network architecture http//www.morawek.at/
  
• Arbeiten/Umts/Umts.html
• Wikipedia (2007) Smart Antenna
• http//en.wikipedia.org/wiki/Smart_antenna
• Lu, Li-Liann Wu, Jean-Lien C. Chen, Wei-Yeh
  (2004) The
• Study of Handoff Prediction Schemes for Resource
• Reservation in Mobile Multimedia Wireless
  Networks
• Advanced Information Networking and Applications,
  2004,
• AINA 2004 18th International Conference on
  Volume 1, 2004
• Page(s) 379 384 Vol.1

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References ... continued

• Levine, David A. Akyildiz, Ian F. Naghshineh,
  Mahmoud
• (1997) A Resource Estimation and Call Admission
  Algorithm
• for Wireless Multimedia Networks Using the Shadow
  Cluster
• Concept Networking IEEE/ACM, Transactions on
  Volume 5,
• Issue 1, Feb. 1997 Page(s) 1-12