Kungekudala, kwezinye izixhobo ezahlukeneyo kunye neblogi yam, ndathetha ngento yokuba uZigBee ufile kwaye lixesha lokungcwaba umlindi wendiza. Ukuze ubeke ubuso obuhle kumdlalo ombi kunye ne-Thread esebenza phezulu kwe-IPv6 kunye ne-6LowPan, iBluetooth (LE) efanelekileyo ngakumbi kule nto yanele. Kodwa ndiza kukuxelela ngale nto ngelinye ixesha. Namhlanje siza kuthetha malunga nokuba iqela elisebenzayo lekomiti ligqibe ukucinga kabini emva kwe-802.11ah kwaye lagqiba ukuba lixesha lokongeza inguqu epheleleyo yento efana ne-LRLP (i-Long-Range Low-Power) kwi-pool yemigangatho ye-802.11, efanayo kwi-LORA. Kodwa oku kwabonakala kungenakwenzeka ukuphumeza ngaphandle kokuxhela inkomo engcwele yokuhambelana nomva. Ngenxa yoko, i-Long-Range yashiywa kwaye kwasala amandla aphantsi kuphela, okukwalungile kakhulu. Isiphumo saba ngumxube we-802.11 + 802.15.4, okanye ngokulula Wi-Fi + ZigBee. Oko kukuthi, sinokuthi iteknoloji entsha ayikhuphisana ne-LoraWAN izisombululo, kodwa, ngokuchaseneyo, iyadalwa ukuze incedise.
Ke, masiqale ngeyona nto ibalulekileyo - Ngoku izixhobo ezixhasa i-802.11ba kufuneka zibe neemodyuli ezimbini zerediyo. Kubonakala ukuba, emva kokujonga i-802.11ah / i-ax kunye neTekhnoloji ye-Target Wake Time (TWT), iinjineli zagqiba ekubeni oku akwanelanga kwaye kufuneka zinciphise kakhulu ukusetyenziswa kwamandla. Kutheni umgangatho ubonelela ngokwahlulahlulo kwiindidi ezimbini ezahlukeneyo zonomathotholo - iRadiyo yoNxibelelwano oluPhambili (PCR) kunye neRadio yokuvusa (WUR). Ukuba ngeyokuqala yonke into icacile, lo ngumsakazo oyintloko, uhambisa kwaye ufumene idatha, ngoko okwesibini akukho kakhulu. Ngapha koko, i-WUR ubukhulu becala sisixhobo sokumamela (RX) kwaye yenzelwe ukusebenzisa amandla amancinci kakhulu ukuze isebenze. Umsebenzi wayo ophambili kukufumana isignali yokuvuka kwi-AP kunye nokwenza i-PCR isebenze. Oko kukuthi, le ndlela inciphisa kakhulu ixesha lokuqala lokubanda kwaye ikuvumela ukuba uvuse izixhobo ngexesha elithile ngokuchaneka okuphezulu. Oku kuluncedo kakhulu xa unayo, yithi, kungekhona izixhobo ezilishumi, kodwa ikhulu elineshumi kwaye kufuneka utshintshe idatha kunye nomnye wabo ngexesha elifutshane. Ngaphezu koko, ingqiqo ye-frequency kunye ne-periodicity yokuvuka ihambela kwicala le-AP. Ukuba, yithi, i-LoRAWAN isebenzisa indlela ye-PUSH xa i-activators ngokwayo ivuka kwaye ihambisa into emoyeni, kwaye ilala ixesha eliseleyo, ngoko kulo mzekelo, ngokuchaseneyo, i-AP ithatha isigqibo sokuba yeyiphi kwaye yeyiphi ifowuni ekufuneka ivuke, kwaye ii-actuators ngokwabo ... azihlali zilala.
Ngoku masiqhubele phambili kwiifomati zesakhelo kunye nokuhambelana. Ukuba i-802.11ah, njengomzamo wokuqala, yenzelwe iibhendi ze-868/915 MHz okanye ngokulula i-SUB-1GHz, ke i-802.11ba sele ilungiselelwe i-2.4GHz kunye ne-5GHz bands. Kwimigangatho "emitsha" yangaphambili, ukuhambelana kwaphunyezwa ngentshayelelo eyayiqondakala kwizixhobo ezindala. Oko kukuthi, ukubala bekusoloko kukuba izixhobo ezidala akufuneki ukuba zikwazi ukuqaphela isakhelo sonke; kwanele ukuba baqonde ukuba esi sakhelo siza kuqala nini kwaye ukuhanjiswa kuya kuhlala ixesha elingakanani. Lulwazi abaluthatha kwintshayelelo. I-802.11ba yayingenjalo, kuba iskimu siqinisekisiwe kwaye sibonakalisiwe (asiyi kuwuhoya umba weendleko okwangoku).
Ngenxa yoko, isakhelo se802.11ba sijongeka ngolu hlobo:
I-preamble engeyona i-HT kunye neqhekeza elifutshane le-OFDM kunye ne-modulation ye-BPSK ivumela zonke izixhobo ze-802.11a/g/n/ac/ax ukuva ukuqala kokuhanjiswa kwesi sikhokelo kwaye zingaphazamisi, zingene kwimodi yokuphulaphula yosasazo. Emva kwentshayelelo kuza indawo yongqamaniso (SYNC), eyi-analogue ye-L-STF/L-LTF. Isebenza ukwenza kube lula ukulungelelanisa ukuphindaphinda kunye nokuvumelanisa umamkeli wesixhobo. Kwaye kulo mzuzu isixhobo sokudlulisa sitshintshela kwelinye ububanzi betshaneli ye-4 MHz. Yantoni? Yonke into ilula kakhulu. Oku kuyimfuneko ukwenzela ukuba amandla ancitshiswe kwaye umlinganiselo we-signal-to-noise ratio (SINR) unokufumaneka. Okanye ushiye amandla njengoko enjalo kwaye ufezekise ukonyuka okukhulu kuluhlu losulelo. Ndingatsho ukuba esi sisisombululo esihle kakhulu, esikwavumela ukuba umntu anciphise kakhulu iimfuno zombane. Masikhumbule, umzekelo, i-ESP8266 eyaziwayo. Kwimowudi yokuhambisa usebenzisa i-bitrate ye-54 Mbps kunye namandla e-16dBm, idla i-196 mA, ephakamileyo ngokunqatshelwe into efana ne-CR2032. Ukuba sinciphisa ububanzi betshaneli ngamaxesha amahlanu kwaye sinciphisa amandla othumelo ngokuphindwe kahlanu, ngoko ke asizukulahlekelwa kuluhlu lothumelo, kodwa ukusetyenziswa kwangoku kuya kuncitshiswa yinto, yithi, malunga ne-50 mA. Ayikuko ukuba oku kubalulekile kwicala le-AP ehambisa isakhelo se-WUR, kodwa ayikabi. Kodwa kwi-STA oku sele kunengqiqo, ekubeni ukusetyenziswa okuphantsi kuvumela ukusetyenziswa kwento efana ne-CR2032 okanye iibhetri ezilungiselelwe ukugcina amandla ixesha elide kunye nemisinga ephantsi yokukhupha. Ngokuqinisekileyo, akukho nto iza simahla kwaye ukunciphisa ububanzi besiteshi kuya kukhokelela ekunciphiseni kwesantya somzila kunye nokunyuka kwexesha lokuhanjiswa kwesakhelo esinye, ngokulandelanayo.
Ngendlela, malunga nesantya sesiteshi. Umgangatho kwifom yayo yangoku inika iinketho ezimbini: 62.5 Kbps kunye ne-250 Kbps. Ngaba uyaliva ivumba leZigBee? Oku akulula, kuba inobubanzi betshaneli ye-2Mhz endaweni ye-4Mhz, kodwa uhlobo olwahlukileyo lokumodareyitha kunye noxinzelelo oluphezulu lwe-spectral. Ngenxa yoko, uluhlu lwezixhobo ze-802.11ba kufuneka lube lukhulu, oluluncedo kakhulu kwiimeko ze-IoT zangaphakathi.
Nangona, linda umzuzu ... Ukunyanzelisa zonke izikhululo ezikuloo ndawo ukuba zithule, ngelixa zisebenzisa i-4 MHz kuphela ye-20 MHz band ... "LE YI-WASTENESS!" - uya kuthetha kwaye uya kuba ulungile. Kodwa hayi, LE YINKCUKACHA YOKWENENE!
Umgangatho ubonelela ngokukwazi ukusebenzisa i-40 MHz kunye ne-80 MHz subchannels. Kule meko, i-bitrate ye-subchannel nganye inokwahluka, kwaye ukuze ihambelane nexesha losasazo, i-Padding yongezwa ekupheleni kwesakhelo. Oko kukuthi, isixhobo sinokuthatha i-airtime kuwo wonke ama-80 MHz, kodwa sisebenzise kuphela kwi-16 MHz. Le yinkcitho yokwenene.
Ngendlela, izixhobo ezijikelezayo ze-Wi-Fi azinalo ithuba lokuqonda oko kusasazwayo apho. Kuba i-OFDM yesiqhelo ayisetyenziswanga ukufaka ikhowudi ye-802.11ba izakhelo. Ewe, kanye ngolo hlobo, umanyano lwakushiya ngokudumileyo oko kwakusebenze ngokungenasiphako iminyaka emininzi. Endaweni ye-OFDM yakudala, iMulti-Carrier (MC)-OOK modulation iyasetyenziswa. Isitishi se-4MHz sahlulwe saba zii-subcarriers ze-16 (?), nganye kuzo isebenzisa i-encoding yaseManchester. Ngexesha elifanayo, intsimi ye-DATA ngokwayo ihlukaniswe ngokwengqiqo ibe ngamacandelo e-4 ΞΌs okanye i-2 ΞΌs ngokuxhomekeke kwi-bitrate, kwaye kwicandelo ngalinye elinjalo inqanaba eliphantsi okanye eliphezulu leekhowudi lingahambelana nelinye. Esi sisisombululo sokuphepha ukulandelelana kwexesha elide le-zero okanye enye. Ukufumana umvuzo omncinci.
Inqanaba le-MAC nalo lenziwe lula kakhulu. Iqulethe kuphela le mimandla ilandelayo:
- Ulawulo lwesakhelo
Ingathatha amaxabiso eBeacon, iWUP, uFundo okanye naliphi na elinye ixabiso elikhethiweyo lomthengisi.
I-Beacon isetyenziselwa ukuvumelanisa ixesha, i-WUP yenzelwe ukuvusa enye okanye iqela lezixhobo, kwaye i-Discovery isebenza kwicala elichasene ne-STA ukuya kwi-AP kwaye yenzelwe ukufumana iindawo zokufikelela ezixhasa i-802.11ba. Le ndawo iqulethe ubude besakhelo ukuba idlula amasuntswana angama-48. - ID
Ngokuxhomekeke kuhlobo lwesakhelo, inokuchonga i-AP, okanye i-STA, okanye iqela le-STAs ekujoliswe kulo esi sakhelo. (Ewe, ungazivusa izixhobo ngokwamaqela, kubizwa ngokuba yi-groupcast wake-ups kwaye intle kakhulu).
- Uhlobo oluxhomekeke (TD)
Intsimi eguquguqukayo. Kuyo ukuba ixesha elichanekileyo liyakwazi ukuhanjiswa, umqondiso malunga nokuhlaziywa kwe-firmware / uqwalaselo kunye nenombolo yenguqulo, okanye into eluncedo ekufuneka i-STA iyazi ngayo.
- Indawo yokukhangela isakhelo (FCS)
Yonke into ilula apha. Le yitshekhisum
Kodwa ukuze iteknoloji isebenze, akwanelanga ukuthumela nje isakhelo kwifomathi efunekayo. I-STA kunye ne-AP kufuneka bavumelane. I-STA ibika iiparamitha zayo, kubandakanywa nexesha elifunekayo ukuqalisa i-PCR. Lonke uthethathethwano lwenzeka kusetyenziswa iifreyimu eziqhelekileyo ze-802.11, emva koko i-STA inokukhubaza i-PCR kwaye ifake i-WUR imowudi yokwenza. Okanye mhlawumbi ndide nilale, ukuba kunokwenzeka. Kuba ukuba ikhona, ke kungcono ukuyisebenzisa.
Okulandelayo kuza ukucudisa ngakumbi iiyure ezixabisekileyo ze-milliamp ezibizwa ngokuba yi-WUR Duty Cycle. Akukho nto inzima, nje i-STA kunye ne-AP, ngokufanisa kunye nendlela eyayiyi-TWT, iyavumelana ngeshedyuli yokulala. Emva koku, i-STA ihlala ilala, ngamanye amaxesha ivula i-WUR imamele "Ngaba ikhona into eluncedo endiyifumeneyo?" Kwaye kuphela ukuba kuyimfuneko, ivusa imodyuli yerediyo ephambili yotshintshiselwano lwetrafikhi.
Itshintsha kakhulu imeko xa kuthelekiswa ne-TWT kunye ne-U-APSD, akunjalo?
Kwaye ngoku i-nuance ebalulekileyo ongayicingi ngokukhawuleza. I-WUR ayinyanzelekanga ukuba isebenze ngamaxesha afanayo njengemodyuli ephambili. Ngokuchasene noko, kunqweneleka kwaye kucetyiswa ukuba isebenze kwisitishi esahlukileyo. Kule meko, umsebenzi we-802.11ba awuphazamisi nangayiphi na indlela ukusebenza kwenethiwekhi kwaye, ngokuchaseneyo, ingasetyenziselwa ukuthumela ulwazi oluluncedo. Indawo, uLuhlu lwabamelwane kunye nokunye okuninzi ngaphakathi kweminye imigangatho 802.11, umzekelo 802.11k/v. Kwaye zeziphi iingenelo ezivuleleke kwiinethiwekhi zeMesh ... Kodwa esi sisihloko senqaku elahlukileyo.
Ngokubhekiselele kwikamva lomgangatho ngokwawo njengoxwebhu, ke . Oko kukuthi, kulo nyaka sinokulindela umgangatho wangempela okanye ubuncinane ukuphunyezwa kokuqala. Lixesha kuphela eliya kuchaza indlela eliya kunwenwa ngayo.
Izinto ezinjalo ... (c) .
Ufundo olucetyiswayo:
umthombo: www.habr.com