Osati kale kwambiri, pazinthu zina zosiyanasiyana komanso mu blog yanga, ndinalankhula zakuti ZigBee wamwalira ndipo ndi nthawi yoika m'manda woyendetsa ndegeyo. Kuti muyike nkhope yabwino pamasewera oipa ndi Thread yogwira ntchito pamwamba pa IPv6 ndi 6LowPan, Bluetooth (LE) yomwe ili yoyenera kwambiri pa izi ndi yokwanira. Koma ine ndikuuzani inu za izi nthawi ina. Lero tikambirana momwe gulu logwira ntchito la komiti lidaganiza zoganiza kawiri pambuyo pa 802.11ah ndipo adaganiza kuti inali nthawi yowonjezera mtundu wathunthu wazinthu ngati LRLP (Long-Range Low-Power) ku dziwe la 802.11 miyezo, yofananira. ku LORA. Koma izi zinali zosatheka kuzikwaniritsa popanda kupha ng'ombe yopatulika yobwerera m'mbuyo. Chotsatira chake, Long-Range inasiyidwa ndipo Low-Power yokha idatsalira, yomwe ilinso yabwino kwambiri. Zotsatira zake zinali zosakaniza za 802.11 + 802.15.4, kapena kungoti Wi-Fi + ZigBee. Ndiko kuti, tikhoza kunena kuti teknoloji yatsopanoyi siili yopikisana ndi mayankho a LoraWAN, koma, mosiyana, ikupangidwa kuti igwirizane nawo.
Kotero, tiyeni tiyambe ndi chinthu chofunika kwambiri - Tsopano zipangizo zomwe zimathandizira 802.11ba ziyenera kukhala ndi ma module awiri a wailesi. Mwachiwonekere, atayang'ana pa 802.11ah / nkhwangwa ndi luso lake la Target Wake Time (TWT), akatswiriwo adaganiza kuti izi sizinali zokwanira ndipo amayenera kuchepetsa kwambiri kugwiritsa ntchito mphamvu. Chifukwa chiyani muyezo umagawika m'mitundu iwiri yosiyana yamawayilesi - Wailesi Yoyambira Yolumikizirana (PCR) ndi Wake-Up Radio (WUR). Ngati ndi zoyamba zonse zimveka bwino, iyi ndi wailesi yaikulu, imatumiza ndi kulandira deta, ndiye kuti yachiwiri siili yochuluka. M'malo mwake, WUR nthawi zambiri imakhala chida chomvera (RX) ndipo idapangidwa kuti igwiritse ntchito mphamvu zochepa kuti igwire ntchito. Ntchito yake yayikulu ndikulandila chizindikiro chodzutsa kuchokera ku AP ndikuyambitsa PCR. Ndiko kuti, njirayi imachepetsa kwambiri nthawi yozizira yoyambira ndikukulolani kudzutsa zida panthawi yomwe mwapatsidwa molondola kwambiri. Izi ndizothandiza kwambiri mukakhala ndi, kunena, osati zida khumi, koma zana ndi khumi ndipo muyenera kusinthanitsa deta ndi aliyense wa iwo mu nthawi yochepa. Kuphatikiza apo, lingaliro la ma frequency ndi periodicity of kudzutsidwa limasunthira ku mbali ya AP. Ngati, titi, LoRAWAN imagwiritsa ntchito njira ya PUSH pamene oyendetsa okhawo amadzuka ndikufalitsa chinachake pamlengalenga, ndikugona nthawi yonseyi, ndiye kuti, m'malo mwake, AP imasankha nthawi ndi chipangizo chomwe chiyenera kudzuka, ndi ma actuators okha ... osati nthawi zonse amagona.
Tsopano tiyeni kusuntha kwa chimango akamagwiritsa ndi ngakhale. Ngati 802.11ah, ngati kuyesa koyamba, idapangidwira magulu a 868/915 MHz kapena kungoti SUB-1GHz, ndiye kuti 802.11ba idapangidwira kale magulu a 2.4GHz ndi 5GHz. M'miyezo "yatsopano" yam'mbuyomu, kuyanjana kudakwaniritsidwa kudzera mu chiwongolero chomwe chinali chomveka ku zida zakale. Ndiko kuti, kuwerengera nthawi zonse kwakhala kuti zida zakale sizifunikira kuti zizindikire chimango chonse; ndikwanira kuti amvetsetse nthawi yomwe chimangochi chidzayamba komanso nthawi yayitali bwanji. Ndi chidziwitso ichi chomwe amachitenga m'mawu oyamba. 802.11ba sizinali choncho, popeza ndondomekoyi yatsimikiziridwa ndikutsimikiziridwa (tidzanyalanyaza nkhani ya ndalama panopa).
Zotsatira zake, chimango cha 802.11ba chikuwoneka motere:
Chiyambi chosakhala cha HT ndi chidutswa chachifupi cha OFDM chokhala ndi kusintha kwa BPSK chimalola zipangizo zonse za 802.11a/g/n/ac/ax kuti zimve chiyambi cha kufalikira kwa chimangochi komanso osasokoneza, kupita kumayendedwe omvera. Pambuyo pa mawu oyamba pamabwera gawo lolumikizirana (SYNC), lomwe kwenikweni limafanana ndi L-STF/L-LTF. Zimathandizira kuti zitheke kusintha ma frequency ndi kulunzanitsa wolandila chipangizocho. Ndipo ndipanthawiyi pomwe chida chotumizira chimasinthira ku njira ina m'lifupi mwake 4 MHz. Zachiyani? Zonse ndi zophweka. Izi ndizofunikira kuti mphamvuyo ichepe komanso kuti chiΕ΅erengero chofananira ndi phokoso (SINR) chitheke. Kapena siyani mphamvu momwe ziliri ndikukwaniritsa kuchuluka kwakukulu kwamitundu yotumizira. Ndinganene kuti iyi ndi njira yokongola kwambiri, yomwe imathandizanso kuti munthu achepetse kwambiri zofunikira zamagetsi. Tiyeni tikumbukire, mwachitsanzo, ESP8266 yotchuka. Pogwiritsa ntchito njira yotumizira pogwiritsa ntchito bitrate ya 54 Mbps ndi mphamvu ya 16dBm, imadya 196 mA, yomwe imakhala yokwera kwambiri ngati CR2032. Ngati tichepetsa kukula kwa tchanelo ndi kasanu ndikuchepetsa mphamvu ya transmitter ndi kasanu, ndiye kuti sitingataye munjira yotumizira, koma kugwiritsa ntchito komweko kudzachepetsedwa ndi gawo, tinene, mpaka pafupifupi 50 mA. Osati kuti izi ndizofunikira pa gawo la AP lomwe limatumiza chimango cha WUR, komabe sizoyipa. Koma kwa STA izi ndi zomveka kale, chifukwa kutsika kochepa kumalola kugwiritsa ntchito chinthu monga CR2032 kapena mabatire opangidwira kusungirako mphamvu kwa nthawi yayitali ndi mafunde otsika otsika. Zachidziwikire, palibe chomwe chimabwera kwaulere ndipo kuchepetsa kukula kwa tchanelo kumabweretsa kuchepa kwa liwiro la njira ndikuwonjezeka kwa nthawi yotumizira chimango chimodzi, motsatana.
Mwa njira, za liwiro la njira. Muyezo mu mawonekedwe ake apano umapereka njira ziwiri: 62.5 Kbps ndi 250 Kbps. Kodi mukumva fungo la ZigBee? Izi sizophweka, chifukwa ili ndi mayendedwe a 2Mhz m'malo mwa 4Mhz, koma mtundu wosiyana wa kusinthasintha ndi kachulukidwe wapamwamba kwambiri. Zotsatira zake, zida za 802.11ba ziyenera kukhala zazikulu, zomwe ndizothandiza kwambiri pazochitika zamkati za IoT.
Ngakhale, dikirani kamphindi ... Kukakamiza masiteshoni onse m'derali kuti akhale chete, pamene akugwiritsa ntchito 4 MHz yokha ya gulu la 20 MHz ... "IZI NDI ZOSANGALATSA!" - mudzanena ndipo mudzakhala olondola. Koma ayi, IZI NDI ZONSE ZONSE!
Muyezowu umapereka mwayi wogwiritsa ntchito ma subchannel 40 MHz ndi 80 MHz. Pankhaniyi, ma bitrate a subchannel iliyonse amatha kukhala osiyana, ndipo kuti agwirizane ndi nthawi yowulutsa, Padding imawonjezedwa kumapeto kwa chimango. Ndiko kuti, chipangizocho chikhoza kukhala ndi nthawi yopuma pa 80 MHz, koma chigwiritseni ntchito pa 16 MHz. Izi ndi kutaya kwenikweni.
Mwa njira, zida zozungulira za Wi-Fi zilibe mwayi womvetsetsa zomwe zikuwulutsidwa pamenepo. Chifukwa OFDM yanthawi zonse SIMAgwiritsidwa ntchito kuyika mafelemu a 802.11ba. Inde, monga choncho, mgwirizanowu unasiya mwachidwi zomwe zinagwira ntchito mosalakwitsa kwa zaka zambiri. M'malo mwa classic OFDM, Multi-Carrier (MC) -OOK modulation amagwiritsidwa ntchito. Njira ya 4MHz imagawidwa m'magawo 16 (?) omwe amagwiritsa ntchito ma encoding a Manchester. Nthawi yomweyo, gawo la DATA palokha limagawidwanso momveka bwino kukhala magawo a 4 ΞΌs kapena 2 ΞΌs kutengera bitrate, ndipo mu gawo lililonse loterolo mulingo wocheperako kapena wapamwamba kwambiri ungafanane ndi umodzi. Ili ndiye yankho kuti mupewe kutsatizana kwa ziro kapena ena. Kuthamangira pamalipiro ochepa.
Mulingo wa MAC nawonso ndiwosavuta kwambiri. Ili ndi magawo otsatirawa okha:
- Kuwongolera Mafelemu
Itha kutenga Beacon, WUP, Discovery kapena mtengo wina uliwonse womwe wogulitsa angasankhe.
Beacon imagwiritsidwa ntchito polunzanitsa nthawi, WUP idapangidwa kuti idzutse chimodzi kapena gulu la zida, ndipo Discovery imagwira ntchito mosiyana kuchokera ku STA kupita ku AP ndipo idapangidwa kuti ipeze malo omwe amathandizira 802.11ba. Mundawu ulinso ndi kutalika kwa chimango ngati upitilira ma bits 48. - ID
Kutengera mtundu wa chimango, imatha kuzindikira AP, kapena STA, kapena gulu la ma STA omwe chimangochi chimapangidwira. (Inde, mutha kudzutsa zida m'magulu, zimatchedwa kudzuka kwamagulu ndipo ndizabwino kwambiri).
- Mtundu Wodalira (TD)
Gawo losinthika. Zili momwemo kuti nthawi yeniyeni ikhoza kufalitsidwa, chizindikiro chokhudza firmware / kasinthidwe kachitidwe ndi nambala ya mtundu, kapena chinachake chothandiza chomwe STA chiyenera kudziwa.
- Frame Checksum Field (FCS)
Zonse ndi zophweka apa. Ichi ndi chekeni
Koma kuti ukadaulo ugwire ntchito, sikokwanira kungotumiza chimango mumtundu wofunikira. STA ndi AP ayenera kuvomereza. STA imafotokoza magawo ake, kuphatikiza nthawi yofunikira kuyambitsa PCR. Kukambitsirana konse kumachitika pogwiritsa ntchito mafelemu okhazikika a 802.11, pambuyo pake STA imatha kuletsa PCR ndikulowetsa mawonekedwe a WUR. Kapena mwina kugona pang'ono, ngati n'kotheka. Chifukwa ngati ilipo, ndiye kuti ndi bwino kuigwiritsa ntchito.
Kenako pakubwera kufinya pang'ono kwa maola amtengo wapatali a milliamp otchedwa WUR Duty Cycle. Palibe chovuta, STA ndi AP chabe, pofananiza ndi momwe zinalili kwa TWT, amavomereza nthawi yogona. Zitatha izi, STA nthawi zambiri amagona, nthawi zina amayatsa WUR kuti amvetsere "Pali chilichonse chothandiza chandifikira?" Ndipo pokhapokha ngati kuli kofunikira, imadzutsa gawo lalikulu lawayilesi pakusinthitsa magalimoto.
Zimasintha kwambiri zinthu poyerekeza ndi TWT ndi U-APSD, sichoncho?
Ndipo tsopano nuance yofunikira yomwe simukuganizira nthawi yomweyo. WUR sichiyenera kugwira ntchito pafupipafupi monga gawo lalikulu. M'malo mwake, ndizofunika ndikulangizidwa kuti zizigwira ntchito panjira ina. Pankhaniyi, magwiridwe antchito a 802.11ba sasokoneza momwe ma network amagwirira ntchito ndipo, m'malo mwake, angagwiritsidwe ntchito kutumiza zidziwitso zothandiza. Malo, Mndandanda wa Oyandikana nawo ndi zina zambiri mkati mwa miyezo ina ya 802.11, mwachitsanzo 802.11k/v. Ndipo ndi maubwino ati omwe amatsegulira maukonde a Mesh ... Koma uwu ndi mutu wankhani ina.
Ponena za tsogolo la muyezo wokha ngati chikalata, ndiye . Ndiko kuti, chaka chino tikhoza kuyembekezera muyeso weniweni kapena osachepera kukhazikitsidwa koyamba. NthaΕ΅i yokha ndiyo idzasonyeza mmene kudzakhala kufalikira.
Zinthu ngati izi ... (c) .
Kuwerenga kovomerezeka:
Source: www.habr.com