VLIR Workshop on library development problems

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VLIR Workshop on library development problems

• The importance of standards in the Internet
• richard.philips_at_ua.ac.be

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The History

• American inventor, and painter of some renown,
  Samuel Morse (1791-1872) was the realizer of
  electric telegraph
• 1875 Alexander Graham Bell designed a device
  that could transmit speech electrically (the
  telephone)
• 1928 Nyquist formulated the laws of digital
  communications

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History (2)

• 1947 UN came into existence
• 1948 Claude Shannon published A Mathematical
  Theory of Comunication
• 1948 Transistor was invented
• 1956 Instalment of the CCITT
• 1970-1980-1990 LSI and VLSI

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History (3)

• 1960-1970 The Arpanet
• ISO 7498 was approved in 1983
• 1990-1995 DoD funded the development of a
  worldwide, satellite-based radio-navigation
  system GPS. (12 billion)
• 1990-2000 Motorola unveils the Iridium System
  concept for global personal communications.
• 1991 NREN (National Research and Education
  Network)

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History (4)

• 2000 231M (English) 404M (Non-English) people
  have Internet access
• 2005 prediction 1.2 billion people will have a
  cell-phone

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The fundamental problem

• Communications is sensitive to errors
• Internal factors
• Loss of energy
• Limited bandwidth
• Delay distortion
• External factors
• White noise

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The fundamental problem
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The fundamental problem

• The influence of distance

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Analog versus Digital

• Analog
• Signals are potentially in an infinite set
• Communication is about reconstruction
• Digital
• Signals are in a finite set, defined beforehand
• Communication is about recognition

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The components of digital communication

• Abstract modem

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The components of digital communication (2)

• Formatting
• Source encoding
• Encryption
• Channel encoding
• Multiplexing
• Modulation

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GPS

• Global Positioning System
• Position on Earth, anytime, any weather
• 24 satellites, 24 in all, orbit at 11,000
  nautical miles above the Earth
• The satellites transmit signals that can be
  detected by anyone with a GPS receiver. Using the
  receiver, you can determine your location with
  great precision.

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GPS (2)

• Components of GPS

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GPS (3)

• Control segment
• 5 ground stations that make sure the satellites
  are working properly
• Space segment
• 24 satellites, each in its own orbit 11,000
  nautical miles above the Earth.
• They are positioned so that we can receive
  signals from six of them nearly 100 percent of
  the time at any point on Earth.
• User segment
• The user segment consists of receivers, which you
  can hold in your hand or mount in your car.

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GPS (4)

• The principle behind GPS is the measurement of
  distance (or "range") between the receiver and
  the satellites. The satellites also tell us
  exactly where they are in their orbits above the
  Earth. It works something like this If we know
  our exact distance from a satellite in space, we
  know we are somewhere on the surface of an
  imaginary sphere with radius equal to the
  distance to the satellite radius. If we know our
  exact distance from two satellites, we know that
  we are located somewhere on the line where the
  two spheres intersect. And, if we take a third
  measurement, there are only two possible points
  where we could be located. One of these is
  usually impossible, and the GPS receivers have
  mathematical methods of eliminating the
  impossible location.

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GPS (5)

• Uses
• Military
• At night, in sandstorms
• The demand was so great that, before the end of
  Operation Desert Storm , more than 9,000
  commercial receivers were in use in the Gulf
  region. They were carried by foot soldiers and
  attached to vehicles, helicopters, and aircraft
  instrument panels. GPS receivers were used in
  several aircraft, including F-16 fighters, KC-135
  aerial refuelers, and B-2 bombers Navy ships
  used them for rendezvous, minesweeping, and
  aircraft operations.

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GPS (6)

• Civilian use
• the tunnel under the English Channel
• tracking is one of the fastest-growing GPS
  applications
• traffic regulation
• In the field of wildlife management, threatened
  species such as the Mojave Desert tortoise are
  being fitted with GPS receivers and tiny
  transmitters to help determine population
  distribution patterns and possible sources of
  disease

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Global System for Mobile Communication (GSM)

• Definition
• Global system for mobile communication (GSM) is a
  globally accepted standard for digital cellular
  communication. GSM is the name of a
  standardization group established in 1982 to
  create a common European mobile telephone
  standard that would formulate specifications for
  a pan-European mobile cellular radio system
  operating at 900 MHz.

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GSM (2)

• GSM network elements

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GSM (3)

• home location register (HLR)The HLR is a
  database used for storage and management of
  subscriptions
• mobile services switching center (MSC)The MSC
  performs the telephony switching functions of the
  system. It controls calls to and from other
  telephone and data systems.
• visitor location register (VLR)The VLR is a
  database that contains temporary information
  about subscribers that is needed by the MSC in
  order to service visiting subscribers.
• authentication center (AUC)A unit called the AUC
  provides authentication and encryption parameters
  that verify the user's identity and ensure the
  confidentiality of each call.

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GSM (4)

• BSCThe BSC provides all the control functions
  and physical links between the MSC and BTS. It is
  a high-capacity switch that provides functions
  such as handover, cell configuration data, and
  control of radio frequency (RF) power levels in
  base transceiver stations. A number of BSCs are
  served by an MSC.
• BTSThe BTS handles the radio interface to the
  mobile station. The BTS is the radio equipment
  (transceivers and antennas) needed to service
  each cell in the network. A group of BTSs are
  controlled by a BSC.

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GSM (5)

• GSM Subscriber Services
• dual-tone multifrequency (DTMF)DTMF is a tone
  signaling scheme often used for various control
  purposes via the telephone network, such as
  remote control of an answering machine. GSM
  supports full-originating DTMF.
• facsimile group IIIGSM supports CCITT Group 3
  facsimile. As standard fax machines are designed
  to be connected to a telephone using analog
  signals, a special fax converter connected to the
  exchange is used in the GSM system. This enables
  a GSMconnected fax to communicate with any
  analog fax in the network.
• Short message servicesA convenient facility of
  the GSM network is the short message service. A
  message consisting of a maximum of 160
  alphanumeric characters can be sent to or from a
  mobile station. This service can be viewed as an
  advanced form of alphanumeric paging with a
  number of advantages. If the subscriber's mobile
  unit is powered off or has left the coverage
  area, the message is stored and offered back to
  the subscriber when the mobile is powered on or
  has reentered the coverage area of the network.
  This function ensures that the message will be
  received.
• Cell broadcastA variation of the short message
  service is the cell broadcast facility. A message
  of a maximum of 93 characters can be broadcast to
  all mobile subscribers in a certain geographic
  area. Typical applications include traffic
  congestion warnings and reports on accidents.
• voice mailThis service is actually an answering
  machine within the network, which is controlled
  by the subscriber. Calls can be forwarded to the
  subscriber's voice-mail box and the subscriber
  checks for messages via a personal security code.
  
• fax mailWith this service, the subscriber can
  receive fax messages at any fax machine. The
  messages are stored in a service center from
  which they can be retrieved by the subscriber via
  a personal security code to the desired fax
  number.

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GSM (6)

• Supplementary Services
• call forwardingThis service gives the subscriber
  the ability to forward incoming calls to another
  number if the called mobile unit is not
  reachable, if it is busy, if there is no reply,
  or if call forwarding is allowed unconditionally.
  
• barring of outgoing callsThis service makes it
  possible for a mobile subscriber to prevent all
  outgoing calls.
• barring of incoming callsThis function allows
  the subscriber to prevent incoming calls. The
  following two conditions for incoming call
  barring exist baring of all incoming calls and
  barring of incoming calls when roaming outside
  the home PLMN.
• advice of charge (AoC)The AoC service provides
  the mobile subscriber with an estimate of the
  call charges. There are two types of AoC
  information one that provides the subscriber
  with an estimate of the bill and one that can be
  used for immediate charging purposes. AoC for
  data calls is provided on the basis of time
  measurements.
• call holdThis service enables the subscriber to
  interrupt an ongoing call and then subsequently
  reestablish the call. The call hold service is
  only applicable to normal telephony.
• call waitingThis service enables the mobile
  subscriber to be notified of an incoming call
  during a conversation. The subscriber can answer,
  reject, or ignore the incoming call. Call waiting
  is applicable to all GSM telecommunications
  services using a circuit-switched connection.
• multiparty serviceThe multiparty service enables
  a mobile subscriber to establish a multiparty
  conversationthat is, a simultaneous conversation
  between three and six subscribers. This service
  is only applicable to normal telephony.
• calling line identification presentation/restricti
  onThese services supply the called party with
  the integrated services digital network (ISDN)
  number of the calling party. The restriction
  service enables the calling party to restrict the
  presentation. The restriction overrides the
  presentation.
• closed user groups (CUGs)CUGs are generally
  comparable to a PBX. They are a group of
  subscribers who are capable of only calling
  themselves and certain numbers.

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