IP telephony Evolution or revolution
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Transcript of IP telephony Evolution or revolution
IP telephony Evolution or revolution
Jan DamsgaardDept. of informatics
Copenhagen Business Schoolhttp://www.cbs.dk/staff/damsgaard/
IP telefoni J. Damsgaard, 2004 2
Agenda
IP telephony IP telephony as evolution IP telephony as revolution VoIP WLAN technology
IP telefoni J. Damsgaard, 2004 3
IP Telephony
Circuit switched Vs. Packet switched IPv4 og IPv6
– Address space from 232 to 2128
– Or one address per square inch on earth
Kilde: www.pcworld.dk
IP telefoni J. Damsgaard, 2004 4
Soft Vs Hard IP telephony Hard IP
– Box inserted between ordinary phone and broadband Internet connection (adsl or cable modem)
– Stationary use – easy move of box– Maturing of existing technology. You can call everyone
Soft IP– Software application that is installed on the computer which
has to be running and connected to the Internet– Mobile use – wireless access– You can all all other users running the same program and if
you kow their alias.
IP telefoni J. Damsgaard, 2004 5
IP telephony as evolution
Automation of existing services Usually it is the teleoperator that installes
and operates hard IP telephony– Drives prices down faster
The existing fixed net is used as analogy and IP telephony does not affect the provision of other services
IP telefoni J. Damsgaard, 2004 6
IP telephony as evolution
All communication through the same net– Integration of data, sound and images
Relocation becomes easy– From place to place (net-plug)– Wireless phones– Globally – But also from work to home
Voicemail can be sent as attachment to email
IP telefoni J. Damsgaard, 2004 7
IP telephony as revolution
Here is a radical departure in the provision of services and the way it is priced
The computer is used as a phone– With speakers and a microphone
The Internet is used as medium– VoDSL (Voice over Digital Subscriber Line)– QoS a problem? (64 kbit/s)
IP telefoni J. Damsgaard, 2004 8
Skype Skype is a piece of software that enables free
telephone conversations from anywhere to anywhere – You do not pay per minute or more the longer distance– Teleoperator cut out of the loop
Skype uses P2P (peer-to-peer) technology where an Instant messenger is combined with telephony
Skype is created by the people behind KaZaAhttp://www.skype.com/
IP telefoni J. Damsgaard, 2004 9
The best from both worlds
RTX has developed a wireless IP telephone Contrary to most other phones the new RTX
phone has two jacks. One for the Internet and one for the PSTN. I.e. you only need one phone and it bridges the two worlds
The wirless RTX phone can run a Skype Client The wireless phone connects through the WLAN Voila – a VoFi (802.11x-enabled VoIP) telephone
Kilde: www.computerworld.dk
IP telefoni J. Damsgaard, 2004 10
And there is more coming Motorola and NEC collaborate to develop an IP
telephone that can roam from a WiFi hotspot to the GSM network without loosing the IP address
Motorola’s components include a WiFi enabled mobile phone and a "mobility manager” that manages the hand over between a WLAN and the public mobile network
IP telefoni J. Damsgaard, 2004 11
And it does not stop Community based WLAN VoIP Users shift from being passive consumers of
telecommucation services they become active providers of telecommuncation services
Imagine that your WLAN together with your neighbour’s WLAN become small pieces of a giant telecommunication infrastructure that in comparison to 3G is much faster
Teleoperators become bit pipes
IP telefoni J. Damsgaard, 2004 12
We have never been mobile
Only serial stationary– We move in steps and therefore we do not need
broadband while in transition (exceeding 64 kb/s)– WLAN at work, in the home, at the gasoline
station at the mall But not between them
This is good news for WLAN and bad news for UMTS
IP telefoni J. Damsgaard, 2004 13
802.11x Standards
Standard 802.11 802.11a 802.11b 802.11g Available Date Jul-97 Sep-99 Sep-99 2002 End Frequency of Operation 2.4 GHz 5 GHz 2.4 GHz 2.4 GHz Total Bandwidth 83.5 MHz 300 MHz 83.5 MHz 83.5 MHz Modulation FHSS OFDM DSSS OFDM Non-overlapping Channels 3 12 3 3 Max. Data Rate 1.2 mbps 54 mbps 11 mbps 54 mbps Typical Range 50 feet 60 feet 100 feet 100 feet
IP telefoni J. Damsgaard, 2004 14
Clusters of public and private WLAN
WLAN broadband
Overlaping but closed WLANs
Overlaping open WLANs
IP telefoni J. Damsgaard, 2004 15
Tragedy of the commons Hardin (1968) describes it as a situation in which too many
actors have privileges to consume a common resource leading to its overuse and eventually collapse.
The tragedy of the commons has been described as a social trap because behavior that gratifies the individual in the short-term has long-term collective costs
For example, every fisherman has the incentive to maximize her current harvest, while the carrying capacity of the fish stock is limited. Therefore, if fishermen combined harvest at a higher rate than the fish can reproduce, the resource will soon be exhausted
This behavioral pattern locks in the individual in a scheme that is destructive for the common resource. In the long term the individuals therefore become victim of their collective actions. Hardin, Garrett (1968). “The Tragedy of the Commons” Science,
December, 13. 1243-1248.
Causes and Counter Measures Counter Measures
Pasture Challenges WBN Challenges Open Commons Closed Commons
Over-grazing Adding more cows Adding more devices than own fair
share
Nothing can be done
Control number of devices
Stealing Taking others cows Taking over the devices of other for own needs
Safeguard own devices
Warn/disable offenders
Poaching Killing others cows Disabling operations of other
members’ devices
Protect own devices
Police the network and punish offenders
Tainting Allowing sick cows in commons
Affecting others’ devices through non-carefulness
Vaccinate own devices
Quarantine infected devices
Contamination Reducing the amount of grass
Maliciously reducing the bandwidth
Nothing can be done
Disable contaminating
devices or members
So what
Moores law– Double the capacity
every 18 months
– Makes the tragedy of the commons to a purely theoretical discussion
Napster and KaZaA– Supercows that eat any
available piece of grass
Year of Introduction Transistors
4004 1971 2,250
8008 1972 2,500
8080 1974 5,000
8086 1978 29,000
286 1982 120,000
Intel386™ processor 1985 275,000
Intel486™ processor 1989 1,180,000
Intel® Pentium® processor 1993 3,100,000
Intel® Pentium® II processor 1997 7,500,000
Intel® Pentium® III processor 1999 24,000,000
Intel® Pentium® 4 processor 2000 42,000,000
Intel® Itanium® processor 2002 220,000,000
Intel® Itanium® 2 processor 2003 410,000,000
Source: http://www.intel.com/research/silicon/mooreslaw.htm
IP telefoni J. Damsgaard, 2004 18
Conclusions
IP telephony is the future– Either as evolution or revolution
Convergence of GSM/GPRS/UMTS/WiFi/UWB/BT into one mobile unit (integrates PDA/Telephone/Data etc.)
Dynamic shift between available resources– Maybe even auction