1. Gabatarwa
Sadarwar Haske Mai Gani (VLC) tana amfani da fitilun LED don watsa bayanai ta mara waya. Wannan takarda ta mai da hankali kan wani yanki na musamman: Sadarwar Kamara ta Optical (OCC) ta amfani da allo na wayar hannu a matsayin masu watsawa da kamarori a matsayin masu karɓa, wanda aka sani da VLC na Wayar Hannu-zuwa-Wayar Hannu (S2SVLC). Binciken ya gwada tsarin S2SVLC a zahiri akan hanyar haɗi mai tsawon 20cm, tare da babban manufa na siffanta tashar sadarwa da bincika halayen fitar da haske na Lambertian na allo na wayar hannu.
Dalilin ya samo asali ne daga yawaitar wayoyin hannu da kuma buƙatar amintaccen sadarwa na na'ura-zuwa-na'ura na kusanci, yana ba da madadin fasahohin RF kamar NFC ko Bluetooth don wasu amfani na musamman.
2. Tsarin Tsarin
Tsarin tsarin S2SVLC ya ƙunshi ƙira mai sauƙi amma mai inganci:
- Mai Watsawa (Tx): Ana canza bayanai (rubutu/kafofin watsa labarai) zuwa rafi na binary. Ana ɓoye wannan rafin cikin hoto inda rago suke daidaita ƙarfin pixel—yawanci fararen pixel don '1' da baƙaƙen pixel don '0'. Ana nuna wannan hoton akan allo na wayar hannu.
- Mai Karɓa (Rx): Kamarar bayan wayar hannu tana ɗaukar hoton allo. Wani algorithm na sarrafa hoto yana ɗauke da ƙarfin pixel zuwa ragin bayanan binary.
Wannan ƙira tana amfani da kayan aikin da ake da su, tana guje wa buƙatar ƙayyadaddun sassa, wanda shine babban fa'ida don aiwatarwa a aikace.
3. Siffanta Tashoshi & Tsari na Lambertian
Wani muhimmin sashe na binciken shine ƙirar tashar haske. Allon wayar hannu ba cikakken tushen Lambertian ba ne (wanda ke haskaka haske daidai a kowane shugabanci). Fitar da shi yana bin tsarin Lambertian na gabaɗaya tare da tsari n. Ribar DC na tashar, H(0), wanda ke ƙayyade ƙarfin hasken da aka karɓa, an ƙirƙira shi kamar haka:
$H(0) = \frac{(n+1)A}{2\pi d^2} \cos^n(\phi) \cos(\psi)$
inda A shine yankin na'urar gano, d shine nisa, \phi shine kusurwar haskakawa, kuma \psi shine kusurwar faɗuwa. Gwajin takardar yana nufin ƙayyade ƙimar gwaji na n don takamaiman allo na wayar hannu da ake gwadawa a ƙarƙashin yanayin gwaji, wanda shine tushe don lissafin kasafin hanyar haɗi daidai da hasashen aikin tsarin.
4. Saitin Gwaji & Sakamako
Gwajin ya kafa hanyar haɗi ta baya-bayan nan sama da 20cm. Wayar hannu mai watsawa tana nuna sanannen tsarin gwaji. Kamarar mai karɓa, wacce aka tsare a takamaiman daidaitawa, tana ɗaukar hotuna. Ta hanyar nazarin ƙarfin pixel da aka karɓa a kusurwoyi ko nisa daban-daban, ana samun tsarin Lambertian n.
Muhimman Sakamako & Bayanin Ginshiƙi: Duk da yake ba a yi cikakken bayani game da takamaiman sakamako na lambobi ba a cikin abin da aka ba da, hanyar tana nuna cewa za a gabatar da sakamako gabaɗaya ta hanyoyi biyu:
- Zanen Tsari na Lambertian: Zanen da ke nuna ƙarfin hasken da aka karɓa (ko daidaitaccen ƙarfin pixel) akan kusurwar fitarwa (\phi). Ana daidaita maki bayanai tare da lanƙwasa $\cos^n(\phi)$. Mafi kyawun ƙimar n (misali, n=1.8, 2.5) tana ƙididdige shugabanci na allo—ƙaramin n yana nuna faɗaɗa katako.
- Matsakaicin Kuskuren Bit (BER) vs. Nisa/Matsakaicin Sigina-zuwa-Amashu (SNR): Babban ma'auni na aiki. Ginshiƙi zai nuna BER yana ƙaruwa yayin da nisa ke ƙaruwa ko SNR yana raguwa. Wurin da BER ya ketare bakin kofa (misali, $10^{-3}$) yana ayyana iyakar aiki na zahiri na hanyar haɗi a ƙarƙashin tsarin daidaitawa da aka gwada (misali, Maɓalli na Kunna-Kashe ta hanyar fararen/baƙaƙen pixel).
Tsawon hanyar haɗi na 20cm yana nuna binciken ya mai da hankali kan yanayin kusa da filin, babban SNR, mai yiwuwa ya cimma ƙaramin BER sosai, yana tabbatar da yuwuwar asali.
5. Muhimman Fahimta & Bincike
6. Cikakkun Bayanai na Fasaha & Tsarin Lissafi
Babban gudummawar fasaha ita ce daidaita daidaitaccen ƙirar tashar VLC don tushen allo. Ƙarfin da aka karɓa P_r an ba shi kamar haka:
$P_r = P_t \cdot H(0) = P_t \cdot \frac{(n+1)A}{2\pi d^2} \cos^n(\phi) T_s(\psi) g(\psi) \cos(\psi)$
Inda:
- $P_t$: Ƙarfin hasken da aka watsa daga yankin allo.
- $T_s(\psi)$: Ribar tace haske (idan akwai).
- $g(\psi)$: Ribar mai tara haske (ruwan tabarau).
- Ga kamara, $A$ yana da alaƙa da girman pixel da yankin hoton allo.
Matsakaicin Sigina-zuwa-Amashu (SNR) a mai karɓa, mai mahimmanci ga BER, shine:
$SNR = \frac{(R P_r)^2}{\sigma_{total}^2}$
inda $R$ shine amsawar mai gano hoto (ga kamara, wannan ya haɗa da ingantaccen ƙididdiga na pixel da ribar canzawa), kuma $\sigma_{total}^2$ shine bambance-bambancen amo na gabaɗaya, gami da hayakin harbi da hayakin zafi daga kewayon karanta na'urar gano kamara.
7. Tsarin Bincike: Nazarin Shari'a
Yanayi: Tabbatar da Biyan Kuɗi na Kusanci
Ka yi tunanin shagon kofi inda ake ba da izinin biyan kuɗi ta hanyar riƙe allo na wayar ku (yana nuna tsari mai motsi, mai ɓoye) kusa da kamarar kwamfutar hannu na ɗan kasuwa.
Aiwatar da Tsarin:
- Ƙirar Tashoshi: Yi amfani da tsarin Lambertian n da aka samo da ƙirar tashoshi don ƙididdige mafi ƙarancin haske na pixel da aka buƙata da ma'auni na bambanci akan allo na abokin ciniki don tabbatar da cewa kamarar ɗan kasuwa ta karɓi siginar da za a iya ɗauke da ita a nisa na 10-30cm na al'ada, ko da a ƙarƙashin hasken shagon.
- Binciken Tsaro: Ƙuntatawar sarari na haske (wanda aka ƙirƙira ta $\cos^n(\phi)$) kadari ne. Kamarar mai sauraro da aka sanya mita 1 nesa da kuma digiri 45 daga axis za ta karɓi siginar da aka rage ta hanyar $\cos^n(45^\circ)/ (d_{eve}/d_{legit})^2$. Don n=2 da nisa na 0.2m (halal) da 1m (eve), siginar mai sauraro tana da ƙarfin ~1/50, yana ba da tsaro na zahiri a matakin jiki.
- Ciniki na Aiki: Don yaƙi da amo daga hasken muhalli, tsarin zai iya amfani da tsawon lokacin fallasa a kan kamarar mai karɓa, yana rage ƙimar bayanai mai tasiri amma yana ƙara dogaro. Ana iya ƙididdige wannan ciniki ta amfani da SNR da ƙirar BER na sama.
8. Aikace-aikace na Gaba & Jagorori
Makomar S2SVLC ba ta cikin yin fiye da WiFi ba, amma a cikin ba da damar sabbin aikace-aikace:
- Haɗin Kai na Kusanci Mai Tsaro: Don shigar da na'urar IoT ko ma'amaloli na kuɗi, inda gajeriyar hanyar haɗi, mai shugabanci, ke zama fasalin tsaro.
- Sanya Wuri & Kewayawa a Cikin Gida: Kamarorin wayoyin hannu suna karanta hasken da aka ɓoye daga fitilun LED na rufi ko alamar alama don sanya wuri daidai-santimita, fagen da ƙungiyoyi kamar Cibiyar Bincike da Haɓakawa ta LiFi a Jami'ar Edinburgh suka yi bincike sosai.
- Haɓaka Gaskiya (AR) Haifar da Abun Ciki: Alloli a cikin gidajen tarihi ko nunin tallace-tallace suna fitar da tsarin bayanai marasa ganuwa (ta hanyar daidaita launi kaɗan) waɗanda tabarau na AR ko kamarorin waya ke ɗauke da su don rufe abun ciki na dijital.
- Jagororin Bincike na Gaba:
- Bayyan OOK: Aiwar daidaitawa mafi girma (misali, Maɓalli Canjin Launi) ta amfani da ƙananan-pixel na RGB na allo don ƙara ƙimar bayanai, kamar yadda aka nuna a cikin bita na wallafe-wallafen.
- Dabarun MIMO: Yin amfani da yankuna da yawa na allo da pixel na kamara a matsayin tashoshi masu kai tsaye, kamar ra'ayin "MIMO na gani" da aka ambata.
- Ka'idoji Masu Ƙarfi: Haɓaka ƙa'idodi don ƙimar flicker na allo, tsare-tsaren coding, da daidaitawa waɗanda ba za a iya gane su ga mutane ba kuma suna da ƙarfi ga tasirin rufewa na kamara.
9. Nassoshi
- Yokar, V. N., Le-Minh, H., Ghassemlooy, Z., & Woo, W. L. (Shekara). Siffanta tashoshi a cikin sadarwar kamara ta optical ta allo-zuwa-kamera. Sunan Taro/Mujalla.
- Kahn, J. M., & Barry, J. R. (1997). Sadarwar infrared mara waya. Proceedings of the IEEE, 85(2), 265-298.
- Haas, H., Yin, L., Wang, Y., & Chen, C. (2016). Menene LiFi?. Journal of Lightwave Technology, 34(6), 1533-1544.
- MIT Media Lab. (n.d.). Sadarwar Optical. An samo daga https://www.media.mit.edu/projects/optical-communications/overview/
- Jami'ar Edinburgh. (n.d.). Cibiyar Bincike da Haɓakawa ta LiFi. An samo daga https://www.lifi.eng.ed.ac.uk/
- Song, L., & Mittal, P. (2021). Umarnin Murya Marasa Ji: Harin Dogon Zango da Tsaro. A cikin 30th USENIX Security Symposium (USENIX Security 21).
- Binciken da aka ambata a cikin PDF game da S2SVLC na barcode/launi [5-9].
Sharhin Mai Binciken Masana'antu: Wasa Mai Amfani Amma Na Musamman
Babban Fahimta: Wannan aikin bai fi game da karya sabon tushe na ka'ida ba kuma ya fi dacewa da tabbatarwa da ƙirar tashar VLC da aka takura da kayan aiki. Ainihin fahimtar shine ƙididdigar allo na wayar hannu a matsayin tushen haske wanda bai dace ba, ƙaramin ƙarfi, wanda aka takura ta sarari—wani muhimmin mataki daga ƙirar Lambertian na littafin zuwa aiwatarwa na zahiri.
Kwararar Ma'ana: Takardar ta bi hanyar injiniya daidai: gano aikace-aikace masu ban sha'awa (S2SVLC), ƙirar tsarin mafi ƙanƙanta mai yuwuwa (allo/kamara), gano babban abin da ba a sani ba (tsarin Lambertian na allo n), da kuma siffanta shi ta hanyar gwaji. Wannan kwararar tana da ƙarfi amma ta al'ada.
Ƙarfi & Kurakurai:
Ƙarfi: Yana amfani da kayan aikin da ake da su (ƙarin farashi sifili), yana ba da aminci na sarari na asali (shugabanci na haske), kuma yana magance gibi na zahiri—ƙirar tashoshi na aiki don allo na masu amfani. Ya yi daidai da yanayin binciken sadarwa mai sauƙi, kamar yadda ayyuka kamar OpenVLC na MIT suka ba da damar gwajin VLC.
Kurakurai: Giwa a cikin ɗaki shine ƙimar bayanai. Daidaitawar binary ta hanyar pixel na allo tana da ƙaramin bandwidth sosai idan aka kwatanta da ko da Bluetooth na gargajiya. Kewayon 20cm shima yana da ƙuntatawa sosai. Binciken, kamar yadda aka gabatar, ya kauce wa gasa mai ƙarfi daga ƙa'idodin RF da aka kafa, masu ƙimar bayanai mai yawa, mai tsayi. Yana jin kamar mafita tana neman babban app fiye da sauƙin canja wurin bayanai kamar QR-code.
Fahimta Mai Aiki: Ga masu bincike: Hanyar tsari ce mai ƙarfi don siffanta wasu tushen haske na matakin mabukaci (TV na LED, fitilun mota). Ga masu haɓaka samfur: Kada ku ɗauki wannan a matsayin maye gurbin sadarwa na gabaɗaya. Musamman sa yana cikin hulɗa masu fahimtar yanayi, na kusanci—tunanin nunin gidan kayan gargajiya suna haifar da abun ciki akan wayar baƙo, amintaccen haɗa na'urori ta hanyar "girgiza" wayoyi tare (kamar yadda aka bincika a cikin bincike kan ka'idojin haɗin kai na aminci), ko hana jabu ta hanyar sa hannun haske. Ya kamata a mai da hankali daga "sadarwa" zuwa "amintaccen musafaha na yanayi."