Sadarwar Haske Mai Gani ta Biyu (VLC) ta daɗe tana fuskantar ƙuntatawa saboda rashin ingantacciyar hanyar haɗin kai mai aiki da inganci. Hanyoyin saukarwa na gargajiya suna amfani da LEDs don watsa bayanai cikin sauri, amma tashoshin haɗin kai suna fuskantar matsaloli masu mahimmanci: masu mayar da haske suna ba da ƙananan ƙimar, hanyoyin da suka dogara da RF (Wi-Fi/Bluetooth) an haramta su a wurare masu mahimmanci (asibitoci, jiragen sama), kuma haɗin kai na infrared ko na VLC na duka-haske suna fama da madaidaicin hanya, tsangwama tare da saukarwa, ko ƙayyadaddun yanayin aikace-aikacen inda hasken haɗin kai ba ya buƙata. Wannan takarda tana magance wannan gibi mai mahimmanci ta hanyar gabatar da hanyar haɗin kai da ta dogara da raƙuman ultrasonic marasa ji, ta yin amfani da Daidaitaccen Maɓalli na Mita (FSK) da tsarin buga na dijital ta hanyar ƙirar murya don ƙirƙirar tashar sadarwa mai hanya, mara daidaituwa wacce ba ta tsoma baki tare da saukarwar haske ba.
Babban ƙirƙira yana cikin raba haɗin kai daga bakan haske. Maimakon haske, tana amfani da raƙuman murya a cikin kewayon kusa-ultrasonic/maras ji (misali, sama da 15 kHz) a matsayin mai ɗaukar kaya.
Na'urar mai amfani tana watsa bayanai ta hanyar daidaita su a kan mai ɗaukar sauti mara ji ta amfani da Daidaitaccen Maɓalli na Mita (FSK). Don tabbatar da samfuri, an yi amfani da mitoci huɗu masu ji (0.5, 1.5, 2.5, 3.5 kHz) don kwaikwayi tsarin 4-FSK, wanda ke wakiltar alamomin dijital. Wannan zaɓi yana amfani da gefen mitar da ke waje da ji na ɗan adam na yau da kullun (20Hz-20kHz) don watsa bayanai.
Layin ƙirar murya guda 10 (mai tazara 0.05m) yana karɓar haɗakar sigina na murya. Daga nan sai a yi amfani da algorithm na tsarin buga na dijital (musamman, Frost beamformer). Wannan algorithm yana sarrafa sigina daga kowane ƙirar murya don samar da katako na karɓa mai jagora, yana ware sigina mai so daga hayaniyar muhalli ko tushen sauti masu tsangwama da suka zo daga hanyoyi daban-daban (misali, -10°, -30°, 20° kamar yadda aka kwaikwayi).
Saitin gwajin ya ƙunshi layin ƙirar murya yana karɓar haɗakar sigina mai ɗauke da sigina mai so da sigina biyu na tsangwama. Tsarin ya nuna ikon tace abin da ake so na watsa haɗin kai ta sarari.
Hoto na 3 a cikin takarda yana gabatar da mahimman tsarin raƙuman sigina: (a) bayanan da aka watsa da sigina masu tsangwama, da (b) haɗakar sigina da aka karɓa, sigina na ƙirar murya ɗaya, da sigina na bayanai da aka dawo da su cikin nasara bayan tsarin buga. Sakamakon ya tabbatar da gani cewa algorithm na tsarin buga ya kashe tsangwama yadda ya kamata kuma ya ciro tsari mai tsabta na bayanai, yana tabbatar da ainihin ra'ayin tace sarari na murya don dawo da haɗin kai.
Frost beamformer shine mai daidaita tsarin buga mai ƙuntatawa. Yana rage ƙarfin fitarwa (danƙe tsangwama da hayaniya) bisa ga ƙuntatawa na layi wanda ke tabbatar da riba ɗaya a cikin hanyar kallo (hanyar isowar sigina mai so). Ana daidaita vector mai nauyi $\mathbf{w}$ don warware: $$\min_{\mathbf{w}} \mathbf{w}^H \mathbf{R}_{xx} \mathbf{w} \quad \text{subject to} \quad \mathbf{C}^H \mathbf{w} = \mathbf{g}$$ inda $\mathbf{R}_{xx}$ shine matrix na haɗin kai na sigina na shigarwa, $\mathbf{C}$ shine matrix na ƙuntatawa, kuma $\mathbf{g}$ shine vector na amsa mai so. Wannan yana ba da damar tace sarari mai inganci.
A cikin 4-FSK, bit 2 na bayanai ana wakilta su ta ɗaya daga cikin mitoci huɗu daban-daban na mai ɗaukar kaya $f_1, f_2, f_3, f_4$. Sigina da aka watsa shine: $$s(t) = A \cos(2\pi f_i t + \phi), \quad \text{for symbol } i$$ Rushewa yawanci ya ƙunshi bankin tacewa ko masu haɗawa da aka kunna zuwa kowane mitar, sai kuma da'irar yanke shawara don zaɓar mitar mafi girman kuzari a cikin lokacin alama.
Aikace-aikacen Tsarin: Kimanta Hanyoyin Haɗin Kai na VLC
Don kimanta wannan da fasahohin gasa, zamu iya amfani da tsarin yanke shawara mai ma'auni da yawa:
Nazarin Lamari: Yanayin ICU na Asibiti
A cikin ICU inda aka haramta RF don guje wa tsangwama da kayan aikin likita, kuma saukarwar VLC tana ba da haske da bayanai masu sauri ga na'urorin lura da marasa lafiya. Haɗin kai na ultrasonic da aka tsara yana ba da damar kwamfutar hannu na ma'aikatan jinya su aika ƙananan sabuntawa na yanayi ko sigina na sarrafawa zuwa cibiyar sadarwa ba tare da fitar da RF ba kuma ba tare da shafar hasken saukarwa mai mahimmanci ba. Tsarin buga yana taimakawa ware sigina daga gefen gadaje daban-daban, yana haɓaka keɓantawa da rage magana ta tsaka-tsaki—fa'ida bayyananne akan RF ko infrared na duk hanyoyi waɗanda ke buƙatar nuni daidai.
Fahimta ta Tsakiya: Babban ƙimar gabatarwar wannan takarda shine dabarun raba bakan da sarari mai wayo. Ta gane cewa matsalar haɗin kai ta VLC ba kawai game da neman wata hanyar sadarwa mara waya ba, amma neman wadda ta dace, ba ta tsangwama, kuma mai inganci ga yanayin rashin daidaituwa. Yin amfani da yankin murya, musamman bandeji na kusa-ultrasonic da ba a yi amfani da shi ba, motsi ne na tunani na gefe wanda ke kaucewa iyakokin magabata.
Kwararar Hankali: Hujja tana da inganci: 1) RF ba ya cikin yawancin wuraren da VLC ke niyya. 2) Haɗin kai na haske (IR/VLC) yana da matsala saboda tsangwama, hanya, da hasken da ba dole ba. 3) Sauti yana ko'ina, mai arha, kuma ana iya sanya shi mara ji. 4) Babban kalubalen sauti shine yanayinsa na duk hanyoyi da hayaniya. 5) Magani: Aiwatar da ingantattun fasahohin sarrafa jeri na RF (tsarin buga) zuwa yankin murya don dawo da hanya da kariya daga hayaniya. Nunin gwaji tare da Frost beamformer ya tabbatar da wannan sarkar hankali.
Ƙarfi & Kurakurai:
Ƙarfi: Kyawawan amfani da kayan aiki na kayayyaki (ƙirar murya, lasifikar) babban abu ne mai fa'ida ga farashi da turawa. Karɓar hanya ta hanyar tsarin buga siffa ce mai mahimmanci wacce ta bambanta shi da hanyoyin haɗin murya na butulci, yana ba da damar tallafawa masu amfani da yawa da kin amincewa da tsangwama. Haɗin kai na asali tare da wuraren da RF ke da mahimmanci siffa ce mai kashewa ga kasuwanni na musamman kamar sararin samaniya da kiwon lafiya.
Kurakurai & Tambayoyin Budadden: Giwa a cikin ɗaki shine ƙimar bayanai. Samfurin yana amfani da masu ɗaukar kaya na kewayon kHz, yana iyakance yuwuwar bandwidth a zahiri idan aka kwatanta da masu ɗaukar kaya na GHz RF ko THz na haske. Takardar ba ta yi magana game da ƙimar bit da aka samu ba, wanda yana da ƙasa (kewayon kbps). Ragewar ultrasonic a cikin iska da tasirin hanyoyi da yawa a cikin wuraren da aka rufe na iya iyakance kewayo da amincin sosai. Daidaicin tsarin buga tare da ƙaramin, layin jeri a cikin ɗaki mai juyawa ba abu ne mai sauƙi ba. Bukatar ƙirar murya a wurin mai karɓa yana ƙara rikitarwar kayan aikin ababen more rayuwa idan aka kwatanta da photodiode guda ɗaya.
Hanyoyin Aiki: Ga masu bincike, wannan aikin yana buɗe filin haɗin gwiwa mai ban sha'awa: Acoustic Backscatter don VLC. Maimakon watsa ultrasonic mai aiki, shin na'urorin mai amfani za su iya daidaita sautin muhalli ko sigina na saukar haske ta hanyar murya kawai? Ga manajoji na samfur a cikin IoT na masana'antu ko sassan gine-gine masu wayo, wannan fasahar ba 'yan takara ce don maye gurbin haɗin kai na Wi-Fi don kiran bidiyo ba. Duk da haka, shine cikakkiyar dacewa ga ƙananan ƙimar, haɗin kai na umarni-da-sarrafawa na lokaci-lokaci a cikin yanayi masu ƙiyayya ga RF. Ba da fifiko ga ayyukan matukin jirgi a saitunan kamar ingantattun wuraren gwamnati, ɗakunan tsabtace masana'antu, ko cikin jiragen ruwa inda ƙa'ida, ba aikin, shine babban direba. Mataki na gaba kai tsaye ga marubutan ya kamata ya zama ƙayyadaddun siffa na yuwuwar ƙimar-kuskure-bit (BER) vs. nisa da ƙimar bayanai, da sanya shi a kan iyakoki na asali na tashar murya, kama da binciken da aka yi don cibiyoyin sadarwar backscatter.