BS ISO/IEC 29143 pdf download – Information technology —Automatic identification anddata capture techniques —Air interface specification for Mobile RFID interrogators

BS ISO/IEC 29143 pdf download – Information technology —Automatic identification anddata capture techniques —Air interface specification for Mobile RFID interrogators.
BS ISO/IEC 29143 specifies mandatory interrogator transmitter properties, wtiicti are defined in Clause 6, a mandatory specification of the media access method for Mobile RFID interrogators in Clause 7, mandatory and optional tag memory structures in Clause 8. optional command extensions Introduced for the special purpose of Mobile RFID applications in ClauseS, and a number of ioformabve annexes providing additional non-mandatory information useful for the implementation of this International Standard, which are Annex A to Annex F.
Due to the lack of a dedicated control channel for Mobile RFID .iterrogators no explicit synchronization of two or more interrogators can be established Mdltionally. Implicit synctvonization as achieved by applying Carrier Sensing or Listen Before Talk is basically not applicable to mobile applications due to the lack of suitable listen thresholds. In general, key figures like the number of active mobile devices at a certain location and the specific local arrangement, e.g. d,stance to the tagged object(s), possible movement of the involved entities arid direction of the antennas are not known In advance. Mobile RFID applications are likely to be more complex and less prsdictable than fixed applications which results in a demand for additional colksion avoidance and collision arbitration mechanisms aimed especially on the requirements of Mobile REID scenarlos
In contrast to fixed RFID applications, where only Tag on Tag collisions have to be resolved by the anti. collision mechanem of the air interface specification, three different types of collisions need to be addressed for Mobile RFID scenarios. Please refer to Annex A for a delailed overview about possible communication errors In Mobile RFID environments.
This International Standard provides a set of simple, robust and effective mechanisms for implementing media access control for Mobile RFID interrogators. All different types of possible collisions are addressed by reducing the probability of unwanted interference andlor providing mechanisms to recover from possible collisions.
The air interface specification for Mobile RFID interrogators described in this International Standard cannot be used on Its own but builds upon an existing RFID command set for fixed RFID that Is used as a fundament for the mechanisms described in this International Standard. Suitable aw interface specifications for this purpose, e.g. ISOIIEC 18000-6 Type C. are provided by ISO and can be found on the internet at www.ao.org
Based on the actual value of the Collision Type Alarm indicator, the Collision Resolution module Is able to resolve the current communication collision using the mechanism specified in 7.3 and 7.4.
7.2.2 Interrogator Collision Detection (lCD) Module
The pwpose of the Interrogator Collision Detection sub-module is to indicate the involvement of a competing interrogator device in an occuning collision such as an Interrogator to Interrogator Collision, see A.4. to be used as an input for the Collision Detection module
NOTE Wi the lolcraing sub-Iauses the term ICD a Positive” Is used to indicate that one or more intederrig interrogalors have been detecled. whereas “lCD is negative is used for Ihe opposite event.
Interference by a nearby mobile or stationary interrogator shall be detected by means of Received Signal Strength Indication (RSSI) where the evaluation of the received signal against the predefined signal threshold value Pee, shall be carried out based on the moving average window size Ws, that shall be selected In accordance with the implemented sampling interval and air interface specific parameters such as interrogator to tag modulation and encoding type
The lCD shall be active for the entire tag response period Tm’ as defined by the basic air interface specification and shall be adapted according the number of blts being transmitted, the link frequency and the number of sub-carrier cycles per symbol (M). In case of tags compllan( to ISOIIEC 18000-6 Type C, the tag response period is defined as T + &,iration of the expected tag response + T if the length of the tag response is known in advance. e.g. transmission of RN 16. If the length of the tag backscatler is veriable. e.g. in case of the transmission of the Ull, the minimum tag response period shall be defined as max(Ti + Ta. T4)
Figure 5 shows how the lCD sub-module shall be implemented using a moving average filter in combination with a comparator, whereas the detailed signal flow Is illustrated for a dedicated example Input In FIgure 6.