MAC: use in Bluetooth & RFID

Bluetooth

• piconet master connected to slave wireless devices
• slaves may be asleep to save power
• two piconets can be bridged through slave to make a scatternet

• profiles give set of protocols for a given application (and there’s 25 of them WTF)
• radio layer uses adaptive freq hopping in 2.4 GHz band
• link layer uses TDM, links auth via pairing
• frame format:

RFID

• reader signal powers tags, tags reply using backscatter:

• gen 2 tag identification:

  1. Reader sends query and sets slot structure
  2. Tags reply in a random slot with possible collisions
  3. Reader asks one tag for identifier — acknowledge
  4. Process continues until no tags left

• reader frames vary depending on type, reader sets timing and knows expected format

• tag responses are data only

• frame structure: