Communication and Networks: A historical perspective EPL 324 Andreas Pitsillides Epl324 Networks: A historical 1 perspective Communicating Humans From human presence on earth: Some selected examples • Sign language? ---first (?) intelligent form of communication? – Allows communication, BUT – Limited by distance (100’s of meters), need visual contact; coded and limited by lack of richness of language – Quality of Communication poor. • Speech – Richness of language, more natural, but limited by distance (100s of meters), no visual needed, could be corrupted by noise, i.e many people talking together (a ‘protocol’ or ‘code of conduct’ is required). Epl324 Networks: A historical 2 perspective Communicating Humans From human presence on earth: Some selected examples • Written – Richness of language, not necessarily limited by distance, limited by encrypted form (must know script form). Must have pen and paper, or similar (not so natural). Can be corrupted by e.g. ‘bad’ handwriting or spilling coffee on the paper (noise) • Pigeon – Not limited by distance much, but limited by volume, – unreliable - message could easily be lost – (pigeon is not necessarily reliable — could go elsewhere, be eaten by a vulture, etc.) Epl324 Networks: A historical 3 perspective Communicating Humans (cont.) • Smoke signals – Limited by distance, need line of sight, limited by volume (rate of information transfer), limited by vocabulary-Smoke ON/Smoke OFF – [is this a big problem? Recall digital/binary communication] – limited by encrypted form (not many are smoke signal readers—could be an advantage. When?), – can be corrupted by wind Epl324 Networks: A historical 4 perspective Communicating Humans (cont.) • Morse code over electrical wires – Not limited as much by distance, – limited by volume over a given time period (information rate), – limited by encrypted form (not many are Morse code readers), – can be corrupted by electromagnetic noise, but not as easily as the smoke signal • Radio signal (as in radio and TV) – Not limited as much by distance, – not limited as much by volume, – not limited by encrypted form, but it is encoded (modulated), – can be corrupted by electromagnetic noise (it touches upon quality of signal). Epl324 Networks: A historical 5 perspective Communicating Humans and communication channels • Radio signals bounced on upper layers of atmosphere, or even satellites – Not limited by distance--universe, not limited a lot by volume, can be influenced by weather conditions, can be influenced by position of satellite (geostationary, etc…) • Binary (digital) computer signals – Not limited by distance by using repeaters, not limited a lot by volume, limited by encrypted form (not many are data signal code readers), not as easily corrupted by noise (if properly designed), offers reliable / dependable quality • Light signals (optical fibers, light bulbs) – Not limited by distance, not limited (at all) by volume, limited by encrypted form, not corrupted by e-m noise, offers reliable / dependable quality • Light bubs • Power lines Epl324 Networks: A historical 6 perspective Some indicative early systems • Polybius (203-120 BC) – Coding: B=21, S=34 – 2 sets of 5 torches behind screens – 2 torches up = Ready-to-send / Clear-to-send – Left screen, then right screen – Bandwidth: ~ 2 words/minute – Remained ‘state-of-the-art’ for roughly 2000 years Epl324 Networks: A historical 7 perspective Some indicative early systems • Claude Chappe (1763-1805) • 1792: Optical semaphore (arms & telescopes) • 2 arms x 7 positions x 4 bar positions = 196 symbols • Operated by two people • Can run full-duplex (but hard!) • Delay: Paris-Lille (190km) in 32 minutes • Bandwidth: ~ 15 bits/minutes • Most of the features of modern networks (routing, error correction, flow control) Epl324 Networks: A historical 8 perspective Some indicative early systems • Electrical Telegraph Morse code – 1837: Cooke and Wheatstone – 25 characters/minute – 1851: Paris – London cable – 1852: 6400km cable in England – 1866: London – New York – 20 words for $100 Epl324 Networks: A historical 9 perspective Some indicative early systems • Telephony (“voice over wires”) – Reiss (1863), Bell (1876),Gray(1876), Edison(1877), Siemens (1878), .... – “This ‘phone’ has way too many shortcomings to consider it as a serious way of communicating. The unit is worthless to us.” [Western Union,1876] Epl324 Networks: A historical 10 perspective Next generation fibre optic communication Fiber to the home - FTTH Epl324 Networks: A historical 11 perspective Light bulbs? • What if every light bulb in the world could also transmit data? • At TEDGlobal, Harald Haas demonstrates, for the first time, a device that could do exactly that. By flickering the light from a single LED, a change too quick for the human eye to detect, he can transmit far more data than a cellular tower -- and do it in a way that's more efficient, secure and widespread. • To watch this video, please visit: • http://www.ted.com/talks/harald_haas_wireless_data_fr om_every_light_bulb.html Epl324 Networks: A historical 12 perspective Communicating Humans and communication channels (cont.) • What do the earlier examples have in common? – Human adaptability and ingenuity in finding different (often ‘unnatural’) ways to communicate – Different channels (guides) have been used (wind, air-space for pigeons, line-of-sight for smoke signals, radio waves, electricity signals, e-m waves, microwave guides, light (optical) waves – Often to surpass limitations of the medium, encryption and noise cancelling techniques are used. At times information is piggy- backed on other more convenient signal (e.g radio modulation) – Offered quality of service must be at acceptable levels To achieve our goal of effective and reliable communication, from anywhere, we need to study communication and networking (starting with the fundamentals) Epl324 Networks: A historical 13 perspective Networks • So far we considered communication between 2 points. • What if we need to communicate with many? Do we need to establish one-to-one communication channels with each one? Is this efficient/practical/feasible? Epl324 Networks: A historical 14 perspective Networks • Previous discussion focused on point-to-point communication. • To be more effective and adaptable with our communication needs and to utilise resources efficiently, communication networks have been invented (recall other man made networks). • Main innovation is – aspect of sharing a common channel (e.g. in a Local Area Network) or a number of common resources (e.g. channels / nodes) and – relaying (i.e. cooperating) messages for others (e.g. in the first Telephone system using (manual) switches, in the Internet using routers, in adhock (e.g. VANETS) and sensor networks with cooperation between the nodes) – A world of interconnected IP (internet) devices leading to concepts such as the Internet of Things, Ambient Intelligence , etc... Epl324 Networks: A historical 15 perspective Networks • Again, as in the choice of appropriate channels, whenever the need arises, different communication networks have been used, as the current needs dictate. Examples of different types of networks still in use: – The Telephone network, – The cellular mobile Telephone Network (GSM, GPRS, UMTS, LTE, 4G) – The Internet – Cable networks – Local Area Networks, Wireless Local Area Networks – Sensor networks, Body Area Networks, Personal Area Networks, Vehicle Adhoc networks (VANETS), Home Area Networks, … – etc… • These networks may use different technologies, BUT fundamentals remain the same Epl324 Networks: A historical 16 perspective Networks • Different networks and technologies require openness, interoperability, standards, protocols, etc… • Above will be part of the networking course • Note: for each one of the above volumes have been written, thousands of man-years invested by the community in research and development, but the results today have proven the worth of the investment. Notable examples include: – The telephone network which has enabled people to communicate from every part of the globe – The Internet (a global network) which allows open access by the world community, from anywhere in the world, including mobile devices – Worth pointing out that the internet is the most complex-large scale man-made system – A view of the evolution of interconnected devices – And to come, the Internet of Things and ambient intelligence • Our aim is to cover the fundamentals, touch upon the technology, brief introduction to analysis of networks, hint upon traffic engineering and design issues, and open research questions and challenges. Most of our examples will be drawn from the internet. Epl324 Networks: A historical 17 perspective End Epl324 Networks: A historical 18 perspective Point to point connection Epl324 Networks: A historical 19 perspective Broadband over power lines ? IEEE spectrum Dept 2004 Epl324 Networks: A historical 20 perspective Shared channel Network Home WLAN Adhoc network network Epl324 Networks: A historical 21 perspective Switching Systems • Manual control—Switch/cord boards Off-Hook Indicator Tip Ring Patch Cord Pairs Manual Ring Epl324 Networks: A historical 22 perspective Network Common resources (e.g. routers) Users Epl324 Networks: A historical 23 perspective routers Cost? From a few dollars to millions of dollars Epl324 Networks: A historical 24 perspective Internet devices JPL: Sensor Webs Epl324 Networks: A historical 25 perspective Internet Map This graph is using over 5 million edges and has an estimated