Hlavnim zroutem energie v GSM telefonu je a) vysilac, b) interni procesor, c) display. I WLAN telefony zrejme budou muset vysilat - a to patrne zhruba na stejnych vykonech jako GSM a budou mit osvetleny display. Co se vykonu procesoru tyce tak predpokladam, ze i WLAN telefony budou data alespon nejak sifrovat (jinak by se skutecne dalo usetrit na vykonu a tedy i spotrebe) a tak ani tady nelze nejaky zasadni rozdil v spotrebe ocekavat (zpracovani IP paketu a zpracovani paketu GSM protokolu neni z hlediska slozitosti zas az tak odlisne). Takze, dokud to neuvidim, budu povazovat vyrok o delsi vydrzi baterek za zbozne prani a marketingove prohlaseni.
Mne se libi potencialni varianta bezdratovych zarizeni, ktere nebudou mit baterii snad vubec: pry budou cerpat energii z prostredi (ale neni ji tu moc volne k dispozici, takze na tato zarizeni si budeme muset pockat jeste dele).
Meli jsme takovou malou svitilnu co nemela vubec baterie a svitila kdyz se opakovane mackala packa (co tocila malym dynamem). Vim, ze podobne veci se stale vyrabeji (i kdyz dneska casto maji dobijeci akumulatory, ktere si "tocenim" nabijete a pak to nejakou chvili funguje i bez prace) - puvodne jsem sem chtel dat link, ale nasel jsem jen tohle . Ano, takovato forma cerpani energie z prostredi se mi take libi. Ale jestli se takhle zacnou vyrabet i mobilni telefony to opravdu nevim ...
Tu lampicku znam take. Co jsem mela na mysli (a podarilo se mi neco opet dohledat), je neco trochu jineho:
Minimalni spotreba enerigie jde (zatim) ruku v ruce s malou potencialni prenosovou rychlosti. Reseni se bude uplatnovat napr. v 802.15.4 (Low Rate WPAN, LR-WPAN) a zrejme hlavne v miniaturnich koncovych bezdratovych zarizenich.
Z popisu 802.15.4 (IEEE Network):
"The low data rate enables the LR-WPAN to consume very
little power. Many applications that suit LR-WPANs, such as
the monitoring and control of industrial equipment, require
exceptionally long battery life so that the existing mainte-nance
schedules of the monitored equipment are not com-promised.
Other applications, such as environmental
monitoring over large areas, may require a very large number
of devices that make frequent battery replacement impracti-cal.
There are still other applications for which batteries
themselves are impractical, and energy for the LR-WPAN
transceiver and the device must be extracted or "mined" from
the environment."
Priklad vyvoje v teto oblasti:
Power Play (3/02) v MIT enterprise Technology Review (http://www.technologyreview.com/articles/wo_cameron032702.asp)
"STMicrolectronics... ultra low power and ultra low bit
rate - each node in the picoradio network will
draw no more than 100 microwatts of power, three orders of
magnitude less than 802.11b's 300 milliwatts. The benefits of
such a low power network are obvious: no batteries are needed
because each node can harvest all the energy it needs from its
environment. Even a Bluetooth-based radio, which can operate
at 70 milliwatts, still needs a battery to operate and thus will
always need to be maintained. ... will demonstrate the feasibility of
picoradio's low-energy protocol. They intend to build fully
operational, built-to-scale network prototype by December....Each node, in its final form, will be no bigger than a shirt button
and will contain several elements: a sensor, or set of sensors, for
measuring elements like temperature, pressure, motion, light or
sound; a microprocessor; an interface to communicate with
other nodes; and a power component, either solar cells or a
piezoelectric polymer that can convert vibrations from the
environment into electricity. ...A sample application, Rabaey says, is climate control for large
buildings. ... To operate on such low power, each node only
communicates with the node closest to it, which in turn signals
the next closest node, creating what Rabaey describes as a
"multi-hop network.""
Ano, samozrejme, ze snizeni objemu prenasenych dat bude znamenat snizeni spotreby - a to proto, ze mensi mnozstvi dat muzeme vyslat za kratsi cas. Vysilani mensiho mnozstvi dat by bylo mozne pokud snizime kvalitu prenaseneho hlasu nebo pouzijeme schopnejsi mechanismus pro jeho kompresi - a ani jedno ani druhe neni zasluha toho, ze jde o prenos po IP. Zamerne samozrejme pomijim snizeni spotreby snizenim vysilaciho vykony, ktere by bylo mozne jen za cenu snizeni dostupnosti a/nebo nutnosti zahustit sit zakladnovych stanic - a to by slo provest i v soucasne GSM siti a tedy by neslo cestne hovorit o tom, ze nova technologie prinese vetsi vydrz baterek (kdyz by ji neprinesla nova technologie, ale hustsi sit zakladnovych stanic). Ve zminemem clanku se o dosahu takovych zarizeni nic nemluvi, ale navzdory tomu, ze me znalosti fyziky nejsou dokonale si troufam tvrdit, ze chceme-li prenaset urcity objem dat do urcite vzdalenosti, budeme na to proste nejakou energii potrebovat.