{"id":70827,"date":"2020-02-21T14:42:12","date_gmt":"2020-02-21T11:42:12","guid":{"rendered":"https:\/\/prohoster.info\/blog\/802-11ba-wur-ili-kak-skrestit-uzha-s-ezhom"},"modified":"2020-03-03T16:14:44","modified_gmt":"2020-03-03T13:14:44","slug":"802-11ba-wur-ili-kak-skrestit-uzha-s-ezhom","status":"publish","type":"post","link":"https:\/\/prohoster.info\/sq\/blog\/administrirovanie\/802-11ba-wur-ili-kak-skrestit-uzha-s-ezhom","title":{"rendered":"802.11ba (WUR) ose si t\u00eb kryq\u00ebzosh nj\u00eb yndyr\u00eb me nj\u00eb eg\u00ebrsir\u00eb","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Para nj\u00eb koh\u00eb t\u00eb shkurt\u00ebr m\u00eb par\u00eb, n\u00eb shum\u00eb burime t\u00eb tjera dhe n\u00eb blogun tim, kam folur p\u00ebr vdekjen e ZigBee dhe se duhet ta varrosim stewardes\u00ebn. P\u00ebr t\u00eb b\u00ebr\u00eb nj\u00eb fytyr\u00eb t\u00eb mir\u00eb n\u00eb nj\u00eb situat\u00eb t\u00eb keqe me Thread, q\u00eb funksionon mbi IPv6 dhe 6LowPan, mjafton nj\u00eb Bluetooth m\u00eb i p\u00ebrshtatsh\u00ebm (LE) p\u00ebr k\u00ebt\u00eb. Por p\u00ebr k\u00ebt\u00eb do t\u00eb flas ndonj\u00ebher\u00eb n\u00eb nj\u00eb tjet\u00ebr rast. Sot do t\u00eb flasim p\u00ebr at\u00eb se si grupi i pun\u00ebs s\u00eb komitetit u mendua mir\u00eb her\u00ebn e dyt\u00eb pas 802.11ah dhe vendosi se ishte koha p\u00ebr t\u00eb shtuar n\u00eb poolin e standardeve 802.11 nj\u00eb version t\u00eb plot\u00eb t\u00eb di\u00e7kaje ngjashme me LRLP (Long-Range Low-Power), n\u00eb ngjashm\u00ebri me LoRA. Por kjo doli t\u00eb ishte e pamundur pa prishur vi\u00e7in e shenjt\u00eb t\u00eb kompakt\u00ebsis\u00eb prapa. N\u00eb fund u hoq dor\u00eb nga Long-Range dhe mbeti vet\u00ebm Low-Power, q\u00eb gjithashtu \u00ebsht\u00eb shum\u00eb mir\u00eb. K\u00ebshtu, u krijua nj\u00eb p\u00ebrzierje e 802.11 + 802.15.4, ose thjesht Wi-Fi + ZigBee. K\u00ebshtu, mund t\u00eb themi se teknologjia e re nuk \u00ebsht\u00eb nj\u00eb konkurrent p\u00ebr zgjidhjet LoraWAN, p\u00ebrkundrazi, krijohet p\u00ebr t'i plot\u00ebsuar ato.
\n<\/a><\/noindex>
\nPra ndaj, le t\u00eb fillojm\u00eb me gj\u00ebn\u00eb m\u00eb t\u00eb r\u00ebnd\u00ebsishme \u2014 Tani n\u00eb pajisjet me mb\u00ebshtetje p\u00ebr 802.11ba duhet t\u00eb jen\u00eb dy modul radio. Duket se, pasi pan\u00eb 802.11ah\/ax me teknologjin\u00eb e Tyre p\u00ebr Zgjim t\u00eb Synuar (TWT), inxhinier\u00ebt vendos\u00ebn se kjo ishte e pamjaftueshme dhe se duhet t\u00eb reduktohet n\u00eb m\u00ebnyr\u00eb radikale konsumimi i energjis\u00eb. P\u00ebr k\u00ebt\u00eb arsye, standardi parashikon ndarjen n\u00eb dy lloje t\u00eb ndryshme radio \u2014 Radio Komunikimi Kryesor (PCR) dhe Radioja p\u00ebr Zgjim (WUR). N\u00ebse me t\u00eb par\u00ebn \u00ebsht\u00eb e qart\u00eb, pasi kjo \u00ebsht\u00eb radioja kryesore q\u00eb d\u00ebrgon dhe merr t\u00eb dh\u00ebna, me t\u00eb dyt\u00ebn nuk \u00ebsht\u00eb aq e qart\u00eb. N\u00eb fakt, WUR \u00ebsht\u00eb kryesisht nj\u00eb pajisje e d\u00ebgjimit (RX) dhe sipas planit duhet t\u00eb konsumoj\u00eb shum\u00eb pak energji p\u00ebr t\u00eb punuar. Detyra e saj kryesore \u00ebsht\u00eb t\u00eb marr\u00eb sinjalin e zgjimit nga AP dhe t\u00eb aktivizoj\u00eb PCR. K\u00ebshtu, ky metod redukton ndjesh\u00ebm koh\u00ebn e fillimit t\u00eb ftoht\u00eb dhe lejon q\u00eb pajisjet t\u00eb zgjohen n\u00eb nj\u00eb koh\u00eb t\u00eb caktuar me sakt\u00ebsi maksimale. Kjo \u00ebsht\u00eb shum\u00eb e dobishme kur keni, p\u00ebr shembull, jo dhjet\u00eb pajisje, por nj\u00ebqind e dhjet\u00eb dhe duhet t\u00eb shk\u00ebmbeni t\u00eb dh\u00ebna me secil\u00ebn prej tyre n\u00eb nj\u00eb periudh\u00eb t\u00eb shkurt\u00ebr. P\u00ebrve\u00e7 k\u00ebsaj, logjika e frekuenc\u00ebs dhe periodik\u00ebs s\u00eb zgjimit kalon n\u00eb an\u00ebn e AP. N\u00ebse, p\u00ebr shembull, n\u00eb LoRAWAN p\u00ebrdoret metodologjia PUSH kur pajisjet ekzekutuese vet\u00eb zgjojn\u00eb dhe d\u00ebrgojn\u00eb di\u00e7ka n\u00eb aj\u00ebr, dhe gjat\u00eb gjith\u00eb koh\u00ebs s\u00eb tjera flen\u00eb, n\u00eb k\u00ebt\u00eb rast ndodhet e kund\u00ebrta; AP vendos kur dhe cila pajisje duhet t\u00eb zgjohesh, dhe pajisjet ekzekutuese\u2026 nuk flen\u00eb gjithmon\u00eb.<\/p>\n

Tani, le t\u00eb kalojm\u00eb n\u00eb formatet e kadrave dhe sigurimin e q\u00ebndrueshm\u00ebris\u00eb. N\u00ebse 802.11ah, si p\u00ebrpjekja e par\u00eb, ishte krijuar p\u00ebr shpeshtat 868\/915 MHz ose thjesht SUB-1GHz, 802.11ba tani \u00ebsht\u00eb e destinuar p\u00ebr shpeshtat 2.4GHz dhe 5GHz. N\u00eb standartet e m\u00ebparshme \"t\u00eb reja\", q\u00ebndrueshm\u00ebria arrihej p\u00ebrmes nj\u00eb preambule q\u00eb kuptohej nga pajisjet m\u00eb t\u00eb vjetra. Kjo do t\u00eb thot\u00eb se llogaritja gjithmon\u00eb ka qen\u00eb q\u00eb pajisjet m\u00eb t\u00eb vjetra nuk kan\u00eb nevoj\u00eb t\u00eb ken\u00eb mund\u00ebsin\u00eb t\u00eb njohin t\u00eb gjith\u00eb kadrin; mjafton q\u00eb t'i kuptojn\u00eb kur do t\u00eb filloj\u00eb ky kad\u00ebr dhe sa do t\u00eb zgjas\u00eb transmetimi. K\u00ebt\u00eb informacion ata e marrin nga preambula. 802.11ba nuk \u00ebsht\u00eb b\u00ebr\u00eb nj\u00eb p\u00ebrjashtim, pasi plani \u00ebsht\u00eb i provuar dhe i testuar (p\u00ebr \u00e7\u00ebshtjen e kostove do t\u00eb heshtim p\u00ebr momentin).<\/p>\n

N\u00eb p\u00ebrfundim, kadri 802.11ba duket ndryshe:<\/p>\n

\"802.11ba
\n
\nPreambula e Non-HT dhe nj\u00eb fragment i shkurt\u00ebr OFDM me modulim BPSK lejon t\u00eb gjitha pajisjet 802.11a\/g\/n\/ac\/ax t\u00eb d\u00ebgjojn\u00eb fillimin e transmetimit t\u00eb k\u00ebtij \u043a\u0430\u0434ra dhe t\u00eb mos nd\u00ebrhyjn\u00eb, duke kaluar n\u00eb modalitetin e d\u00ebgjimit t\u00eb frekuenc\u00ebs. Pas preambul\u00ebs vjen fusha e sinkronizimit (SYNC), e cila esencialisht \u00ebsht\u00eb analogu i L-STF\/L-LTF. Ajo sh\u00ebrben p\u00ebr t\u00eb mund\u00ebsuar rregullimin e frekuenc\u00ebs dhe sinkronizimin e marr\u00ebsit t\u00eb pajisjes. Dhe k\u00ebtu marr\u00ebsi kalon n\u00eb nj\u00eb gjer\u00ebsi tjet\u00ebr kanali prej 4MHz. Pse? E gjith\u00eb kjo \u00ebsht\u00eb shum\u00eb e thjesht\u00eb. Kjo \u00ebsht\u00eb e nevojshme p\u00ebr t\u00eb ulur fuqin\u00eb dhe p\u00ebr t\u00eb arritur nj\u00eb raport t\u00eb krahasuesh\u00ebm t\u00eb sinjalit ndaj fuqis\u00eb me zhurm\u00ebn (SINR). Ose ta l\u00ebm\u00eb fuqin\u00eb si\u00e7 \u00ebsht\u00eb dhe t\u00eb arrijm\u00eb nj\u00eb rritje t\u00eb konsiderueshme t\u00eb distanc\u00ebs s\u00eb transmetimit. Do ta quaja k\u00ebt\u00eb zgjidhje mjaft elegante, dhe gjithashtu, q\u00eb lejon nj\u00eb ulje t\u00eb konsiderueshme t\u00eb k\u00ebrkesave p\u00ebr burimet e energjis\u00eb. Le t\u00eb kujtojm\u00eb, p\u00ebr shembull, popullorin ESP8266. N\u00eb modin e transmetimit me nj\u00eb bitrate prej 54 Mbps dhe fuqi prej 16dBm, ai konsumon 196 mA, q\u00eb \u00ebsht\u00eb ekstremisht shum\u00eb p\u00ebr di\u00e7ka si CR2032. N\u00ebse e ulim gjer\u00ebsin\u00eb e kanalit pes\u00ebfish dhe ulim fuqin\u00eb e transmetuesit pes\u00ebfish, at\u00ebher\u00eb praktikisht nuk do t\u00eb humbim n\u00eb distanc\u00ebn e transmetimit, por do t\u00eb arrijm\u00eb nj\u00eb reduktim t\u00eb duksh\u00ebm t\u00eb konsumit t\u00eb energjis\u00eb, le t\u00eb themi, rreth 50 mA. Nuk \u00ebsht\u00eb se kjo \u00ebsht\u00eb kritike p\u00ebr AP-n\u00eb q\u00eb transmeton kadra p\u00ebr WUR, por akoma \u00ebsht\u00eb e mir\u00eb. Megjithat\u00eb, p\u00ebr STA ka kuptim, pasi nj\u00eb konsum m\u00eb i ul\u00ebt lejon p\u00ebrdorimin e di\u00e7kaje si CR2032 ose baterive t\u00eb dizajnuara p\u00ebr ruajtje t\u00eb gjat\u00eb energjie me norma t\u00eb ulta shkarkimi. Natyrisht, asgj\u00eb nuk \u00ebsht\u00eb falas dhe ulja e gjer\u00ebsis\u00eb s\u00eb kanalit do t\u00eb \u00e7oj\u00eb n\u00eb nj\u00eb ulje t\u00eb shpejt\u00ebsis\u00eb kanale me rritjen e koh\u00ebs s\u00eb transmetimit t\u00eb nj\u00eb kadre p\u00ebrkat\u00ebsisht. <\/p>\n

P\u00ebrsa i p\u00ebrket shpejt\u00ebsis\u00eb s\u00eb kanalit. Standarti aktual parashikon dy mund\u00ebsi, 62.5 Kbps dhe 250 Kbps. E ndjeni, ZigBee e ndjen? Kjo s'\u00ebsht\u00eb rast\u00ebsi, sepse ka gjer\u00ebsin\u00eb e kanalit 2Mhz n\u00eb vend t\u00eb 4Mhz, por me nj\u00eb tip tjet\u00ebr modulimi me densitet m\u00eb t\u00eb lart\u00eb spektral. Si rezultat, radiusi i veprimit t\u00eb pajisjeve 802.11ba duhet t\u00eb jet\u00eb m\u00eb i madh, q\u00eb \u00ebsht\u00eb mjaft i dobish\u00ebm p\u00ebr skenar\u00ebt IoT brenda ambienteve.<\/p>\n

Megjithat\u00eb, prisni\u2026 T\u00eb detyrosh t\u00eb gjitha stacionet n\u00eb rreth t\u00eb heshtin, duke p\u00ebrdorur vet\u00ebm 4 MHz nga brezi 20 MHz\u2026 \"KJO \u00cbSHT\u00cb SHP\u00cbRDORIM!\" \u2014 do t\u00eb thoni dhe do t\u00eb keni t\u00eb drejt\u00eb. Por jo, KJO \u00cbSHT\u00cb E V\u00cbRTETA SHP\u00cbRDORIM!<\/p>\n

\"802.11ba
\n
\nStandarti lejon p\u00ebrdorimin e n\u00ebndeg\u00ebve 40 MHz dhe 80 MHz. N\u00eb t\u00eb nj\u00ebjt\u00ebn koh\u00eb, shpejt\u00ebsit\u00eb e \u00e7do n\u00ebndege mund t\u00eb jen\u00eb t\u00eb ndryshme, dhe p\u00ebr t'u p\u00ebrputhur me koh\u00ebn e transmetimit, n\u00eb fund t\u00eb rameve shtohet Padding. K\u00ebshtu, pajisja mund t\u00eb z\u00eb koh\u00ebn eterike n\u00eb t\u00eb gjith\u00eb 80 MHz, nd\u00ebrsa e p\u00ebrdor vet\u00ebm 16 MHz. Ky \u00ebsht\u00eb nj\u00eb shp\u00ebrdorim i v\u00ebrtet\u00eb.<\/p>\n

P\u00ebr m\u00eb tep\u00ebr, pajisjet e tjera Wi-Fi nuk kan\u00eb asnj\u00eb mund\u00ebsi t\u00eb kuptojn\u00eb se \u00e7far\u00eb po transmetohet n\u00eb eter. Sepse p\u00ebr kodimin e kuadrove 802.11ba nuk p\u00ebrdoret OFDM-i i njohur p\u00ebr ta. Po, ashtu, aleanca e braktisi at\u00eb q\u00eb ka funksionuar pa ndales\u00eb p\u00ebr shum\u00eb vite. N\u00eb vend t\u00eb OFDM-it klasik, p\u00ebrdoret modulimi Multi-Carrier (MC)-OOK. Kanali 4MHz ndahet n\u00eb 16(?) n\u00ebn-nivele, secili prej t\u00eb cil\u00ebve p\u00ebrdor kodimin Manchester. N\u00eb t\u00eb nj\u00ebjt\u00ebn koh\u00eb, fusha e t\u00eb dh\u00ebnave \u00ebsht\u00eb gjithashtu logjikisht e ndar\u00eb n\u00eb segmente sipas 4 \u03bcs ose 2 \u03bcs n\u00eb var\u00ebsi t\u00eb bit-rate-it, dhe n\u00eb secilin segment t\u00eb till\u00eb, nj\u00ebsi mund t\u00eb p\u00ebrfaq\u00ebsohet me nivel t\u00eb ul\u00ebt ose t\u00eb lart\u00eb kodimi. Ky \u00ebsht\u00eb nj\u00eb zgjidhje p\u00ebr t\u00eb evituar nj\u00eb varg t\u00eb gjat\u00eb zerosh ose nj\u00ebsh. Scrambling n\u00eb minimum.<\/p>\n

\"802.11ba
\n
\nNiveli MAC gjithashtu \u00ebsht\u00eb jasht\u00ebzakonisht i thjeshtuar. Ai p\u00ebrmban vet\u00ebm fushat e m\u00ebposhtme:<\/p>\n