index.md (1132B)
1 +++ 2 title = "MAC: use in Bluetooth & RFID" 3 +++ 4 5 # MAC: use in Bluetooth & RFID 6 **Bluetooth** 7 8 - piconet master connected to slave wireless devices 9 - slaves may be asleep to save power 10 - two piconets can be bridged through slave to make a scatternet 11 12 ![screenshot.png](4f23b094f7fad480fcbf760ff5304b6d.png) 13 14 - profiles give set of protocols for a given application (and there’s 25 of them WTF) 15 - radio layer uses adaptive freq hopping in 2.4 GHz band 16 - link layer uses TDM, links auth via pairing 17 - frame format: 18 19 ![screenshot.png](a2ee8019c9a5cca230bb3b7b7a6c4732.png) 20 21 **RFID** 22 23 - reader signal powers tags, tags reply using backscatter: 24 25 ![screenshot.png](602a12f8a67d51f5188925a231fb9c13.png) 26 27 - gen 2 tag identification: 28 29 1. Reader sends query and sets slot structure 30 2. Tags reply in a random slot with possible collisions 31 3. Reader asks one tag for identifier — acknowledge 32 4. Process continues until no tags left 33 34 - reader frames vary depending on type, reader sets timing and knows expected format 35 - tag responses are data only 36 - frame structure: 37 38 ![screenshot.png](e8fed776415462764a16704acb52b44d.png)