| dbo:abstract |
Traffic indication map (en anglès, mapa d'indicació de tràfic) és una estructura emprada en les trames de manegament del protocol IEEE 802.11. La trama TIm està definida dins l'apartat 7.3.2.6 del document 802.11-1999 (ca) Traffic indication map (TIM) is a structure used in 802.11 wireless network management frames. The Traffic indication map information element is covered under section 7.3.2.6 of 802.11-1999 standard. The IEEE 802.11 standards use a bitmap to indicate to any sleeping listening stations that the Access Point (AP) has buffered data waiting for it. Because stations should listen to at least one beacon during the listen interval, the AP periodically sends this bitmap in its beacons as an information element. The bit mask is called the Traffic Indication Map and consists of 2008 bits, each bit representing the Association ID (AID) of a station. However in most situations an AP only has data for a few stations, so only the portion of the bitmap representing those stations needs to be transmitted. Because the bitmap is never transmitted in its entirety, it is referred to as a virtual bitmap, and the portion that is actually transmitted is referred to as a partial virtual bitmap. The structure of the TIM is following: element ID(1 octet)identifies a TIM elementlength(1 octet)the size of the whole element (5 to 255)DTIM_count(1 octet)the number of beacons remaining before a DTIM (including this frame, so 0 means that this frame is a DTIM)DTIM_period(1 octet)A scaling factor indicating that only every nth beacon includes a TIM. Stations in low-power mode will remain asleep and only wake to listen for those beacons, to determine whether they should also remain awake to receive data frames.bitmap_control.offset(7 bits)bitmap_control.broadcast(1 bit)1 when one or more broadcast or multicast frames are queued. This means that all stations should wake up.partial_virtual_bitmap(8 to 2008 bits)This comprises (length-4)×8 bits, each representing a currently-associated station. The low-order bit of the first octet represents station with association ID (bitmap_control.offset×16). Bits outside the partial bitmap are implicitly zero. (en) |
| dbo:wikiPageExternalLink |
http://linuxwireless.org/en/developers/Documentation/ieee80211/power-savings http://www.dd-wrt.com/wiki/index.php/Advanced_wireless_settings%23DTIM_Interval http://techie-buzz.com/tutorials/wifi-demystified-part-i.html |
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| dbo:wikiPageWikiLink |
dbr:Beacon_frame dbc:Local_area_networks dbr:Wireless_access_point dbr:Wi-Fi dbr:Wi-Fi_Alliance dbc:Wireless_networking dbr:Bitmap dbr:IEEE_802.11 dbr:Multicast dbr:Listening_station dbr:Bit_mask dbr:CSMA/CA |
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dbt:Cite_journal dbt:Cite_web dbt:Reflist |
| dct:subject |
dbc:Local_area_networks dbc:Wireless_networking |
| gold:hypernym |
dbr:Structure |
| rdf:type |
yago:WikicatLocalAreaNetworks yago:Artifact100021939 yago:ComputerNetwork103085333 yago:Instrumentality103575240 yago:LocalAreaNetwork103681477 yago:Network103820728 yago:Object100002684 yago:PhysicalEntity100001930 dbo:Building yago:System104377057 yago:Whole100003553 |
| rdfs:comment |
Traffic indication map (en anglès, mapa d'indicació de tràfic) és una estructura emprada en les trames de manegament del protocol IEEE 802.11. La trama TIm està definida dins l'apartat 7.3.2.6 del document 802.11-1999 (ca) Traffic indication map (TIM) is a structure used in 802.11 wireless network management frames. The Traffic indication map information element is covered under section 7.3.2.6 of 802.11-1999 standard. The IEEE 802.11 standards use a bitmap to indicate to any sleeping listening stations that the Access Point (AP) has buffered data waiting for it. Because stations should listen to at least one beacon during the listen interval, the AP periodically sends this bitmap in its beacons as an information element. The bit mask is called the Traffic Indication Map and consists of 2008 bits, each bit representing the Association ID (AID) of a station. (en) |
| rdfs:label |
Traffic indication map (ca) Traffic indication map (en) |
| owl:sameAs |
freebase:Traffic indication map yago-res:Traffic indication map wikidata:Traffic indication map dbpedia-ca:Traffic indication map https://global.dbpedia.org/id/4wLVU |
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wikipedia-en:Traffic_indication_map?oldid=1066547666&ns=0 |
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wikipedia-en:Traffic_indication_map |
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dbr:Delivery_traffic_indication_message dbr:Delivery_Traffic_Indication_Message dbr:DTIM |
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dbr:Beacon_frame dbr:Delivery_traffic_indication_message dbr:Delivery_Traffic_Indication_Message dbr:DTIM |
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wikipedia-en:Traffic_indication_map |