TECOProtocol Optimizationsusing anonymous EPC   Gen2 Inventories
Local Inventory Problem      How many products of a       certain type are in a              shelf ?4-Apr-12        Copyri...
Conventional Solution            10000                                                                                    ...
Problem: Channel Arbitration                                                                        S ing le Tag Repl y   ...
Idea 1: No IDs - just count                                                              S ing le Tag Repl y              ...
Idea 2: Count Collisions and                    empty slots                               C ollided R eply                ...
Estimation of # Tags                in Slotted Aloha Frame            Lower bound            Estimation      Source: Vogt,...
Algorithm  (1) Select Product (prefix in EPC memory)  (2) Start a new Round of 2Q slots  (3) Count Success, Empty and Coll...
Fully EPC Gen2 compatible              Query                                           Power-up & ~killed                 ...
Tag Requirements     EPC Gen2     ...4-Apr-12     Copyright TecO 2007, Restricted Use   10
Reader Requirements          Stage 1:             Get # of collisions             Get # of slots / frames             Sel...
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Protocol Optimizations using anonymous EPC Gen2 Inventories

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Protocol Optimizations using anonymous EPC Gen2 Inventories

  1. 1. TECOProtocol Optimizationsusing anonymous EPC Gen2 Inventories
  2. 2. Local Inventory Problem How many products of a certain type are in a shelf ?4-Apr-12 Copyright TecO 2007, Restricted Use 2
  3. 3. Conventional Solution 10000  Use high level interfaces .95 .99  Get IDs of all/selected 8000 tags 6000 Problem:  Long readingstime (ms) m e s ) ( t i  Static environment 4000  Still uncertainty 2000 0 Solution: 0 10 20 30 40 50 60 70 80 number of tags  Statistical approach Source: Vogt, H. (2002). Efficient Object Identification with Passive RFID Tags. 4-Apr-12 Copyright TecO 2007, Restricted Use 3
  4. 4. Problem: Channel Arbitration S ing le Tag Repl y QueryRep or Interrogato r Select CW Query CW Ack CW QueryRep QueryAdjust if EPC is valid NAK if EPC NAK is invalid Ta g RN16 PC + EPC+ CRC16 T4 T1 T2 T1 T2 C ollided R eply No Repl y Invalid AC K Inte rrogato r Query CW QueryR CW QueryRep CW Ack CW QueryRep Collision No No Detected Reply Reply Ta g RN16 RN16 T1 T2 T1 T3 T1 T34-Apr-12 Copyright TecO 2007, Restricted Use 4
  5. 5. Idea 1: No IDs - just count S ing le Tag Repl y QueryRep or Interrogato r Select CW Query CW Ack CW QueryRep QueryAdjust if EPC is valid NAK NAK if EPC is invalid Ta g RN16 PC + EPC+ CRC16 T4 T1 T2 T1 T2 50% Speed up4-Apr-12 Copyright TecO 2007, Restricted Use 5
  6. 6. Idea 2: Count Collisions and empty slots C ollided R eply N o Re ply Inte rrogato r Query CW Query CW Collision No Detecte d Reply Tag RN16 T1 T2 T1 T3 Collision means 2 or more Tags calculate: min # of tags estimate: # tags4-Apr-12 Copyright TecO 2007, Restricted Use 6
  7. 7. Estimation of # Tags in Slotted Aloha Frame Lower bound Estimation Source: Vogt, H. (2002). Efficient Object Identification with Passive RFID Tags.4-Apr-12 Copyright TecO 2007, Restricted Use 7
  8. 8. Algorithm (1) Select Product (prefix in EPC memory) (2) Start a new Round of 2Q slots (3) Count Success, Empty and Collisions (4) Calculate estimated and minimal number of Tags4-Apr-12 Copyright TecO 2007, Restricted Use 8
  9. 9. Fully EPC Gen2 compatible Query Power-up & ~killed Slot NEW ROUND QueryRep slot CMD: Query [mismatched QueryAdjust Counter inventoried or SL flags] Reply: None CMD: Select Action: Return to ready Ready Reply: None. Note 1 CMD: Query NEW ROUND Action: New round CMD: Query [slot > 0 & matching Reply: Note 3 (inventoried & SL) flags] CMD: All other Reply: None Action: Remain in ready Reply: None CMD: QueryRep, QueryAdjust [slot <> 0] Arbitrate Reply: None NEW ROUND CMD: QueryAdjust, QueryRep [slot=0] CMD: Query [slot = 0 & matching Reply: New RN16 (inventoried & SL) flags] CMD: Select Reply: New RN16 Action: Return to ready Reply: None. Note 1 CMD: Query Action: New round CMD: QueryAdjust [slot = 0] Reply Reply: New RN16 Reply: Note 3 CMD: All other Action: Return to arbitrate Reply: None. CMD: ACK [valid RN16] CMD: ACK [valid RN16] CMD: None within time T2 Reply: PC, EPC, CRC-16 Reply: PC, EPC, CRC-16 Action: Return to arbitrate CMD: Req_RN [invalid RN16] Reply: None. Reply: None Acknowledged CMD: Req_RN [valid RN16] & {access password = 0} Reply: Handle CMD: Req_RN [valid RN16] & {access password <> 0} CMD: ACK [valid han dle] Reply: handle Reply: PC, EPC, CRC-1 6 CMD: Req_RN, Read, Write, Lock, BlockWrite, BlockErase Reply: See state-transition tables CMD: Select CMD: Kill [valid handle & kill password = 0] Action: Return to ready Open Reply: Error code Reply: None. Note 1 CMD: Kill, Access [invalid handle] CMD: Query Reply: None Action: New round Reply: Notes 2, 3 CMD: Access [valid handle & valid access password] CMD: QueryRep, QueryAdjust Reply: handle when done4-Apr-12 Action: Return to ready Copyright TecO 2007, Restricted Use 9
  10. 10. Tag Requirements  EPC Gen2  ...4-Apr-12 Copyright TecO 2007, Restricted Use 10
  11. 11. Reader Requirements  Stage 1: Get # of collisions Get # of slots / frames Select product group*  Stage 2: Set # of slots/frames  Stage 3: Raw Reader/No Firmware Change Algorithm (i.e. No ACKs) * product distribution could also be estimated4-Apr-12 Copyright TecO 2007, Restricted Use 11

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