ITRC20120002A1 - METHOD AND SYSTEM FOR THE USE OF RFID TAGS AS A COMMUNICATION CHANNEL IN AN RFID AREA NETWORK (RAN) - Google Patents

Description

Method and system for using RFID tags as a communication channel In

an RFID Area Network (RAN)

SUMMARY OF THE INVENTION

The invention proposes the method and system for the creation of so-called RANs (RFID Area Networks (in analogy with LANs, Locai Area Networks, PANs, Personal area Networks, etc.) consisting of a group of RFID Readers in which they are implemented the functions to exchange data in unlcast or broadcast mode within the generic RAN, Yes

it also proposes the method for using RFID technology (specifically, tags) such as

"communication channel" that supports the exchange of data of different nature in analogy with traditional short-range wireless communication technologies (WiFi, ZigBee, Bluetooth).

BACKGROUND

In accordance with the recommendations provided in EPC Tag Data Standard ver, 1.6 of 2011, the memory of a Tag Gen2 is divided into four blocks: (ì) Reserved Bank or Bank 00, (li) EPC

Bank or Bank 01, (Hi) TID Bank or Bank 10, (tv) User Bank or Bank 11 (Fig. 1), Bank 00 contains

the lock functions (protection of a memory area) and kill (permanent deactivation of the

Tag) accessible by 32-bit password, Bank 10 contains general information

on the size and characteristics of the Tag (model, manufacturer, etc.}. In the EPC Bank

it contains both control information and "Business Data" (Fig. 2), both a

support of the so-called EPC code that uniquely identifies the object on which the

RFID tag. In fact, the following fields are distinguished;

â € ¢ CRC (16 hits); allows you to check for errors on the remaining memory blocks and à ̈

automatically generated by the RFID Tag;

â € ¢ Protocol Control (PC) (16 bit): control information divided into:

1. Length (5 bits): represents the number of IG-bit words included as a whole

in the PC field and in the EPC field;

2. User Memory Indicator (UMt) (1 bit): indicates if Bank 11 is present and contains data;

3. XPC Indicator (XI) (1 bit): indicates if an XPC is present;

4. Number System Identìfier (NSI) (9 bit): other control information divided into:

4.1 Toggle (1 bit): allows to distinguish EPC global applications [Toggle = 0) from ISO applications (Toggle = 1).

4.2 Attribute / AFI (8 hit): if Toggle = 0 this field is considered to be of the "Attribute" type, used to determine if the physical object on which a Tag is affixed requires special handling of any type ( e.g. hazardous material); if Toggle = 1 this field is considered to be of the AFI type, (Application Family Identìfìer) to indicate a non-EPC global application in accordance with the ISO / IEC 15961 standard.

* EPC {variable length): unique identifier of the object on which the Tag is affixed; in the case of an EPC global application, the "EPC code" is considered, in the case of an ISO application, the "individual Unique Identity" is considered.

* Extended Protocol Contract (XPC (variable length): "bit dì paddìng" used to complete any 16 bit words.

The AFI contains information on the type of application for which the RFID Tag is intended. It defines the type of data that is stored in the Tag so that these can be differentiated and, therefore, filtered for different areas and applications. ISO / IEC 15961 specifies both AFI and ASF (Application Sub Family). AFI and ASF are assigned by GS1 (Application Identifiers - Als), by ANSI MH-10 (Data Identifiers - Dls), by ATA / IATA (Text Element identifiers - TEls). part of memory on which a user has the option of entering information relating to the object on which the Tag is affìsso, the main standard that governs the encoding and decoding of the User Bank is ISO / IEC 15962: 2004. In version 1.6 of the "EPC Tag Data Standard" it is specified how the ISO / IEC 15962: 2004 is applied to the second generation RFID tags. Logically, the content of the User Bank is a set of name-value pairs where the part of the name is a 01 D (Object Identifiers defined according to the syntax ASN.1) and the value is a string of characters . Possible examples of OID notation are:

* (ìso (l) standard (O) rfid -data-protocol (15961)} (ASN.1 notation);

* 1.0.15961 (dot notation);

* / [SO / Standard / 15961 (OiD-IRI notation);

* urn: oid: 1.0.15961. ff (URN notation - RFC3061).

On the physical level, the first few bits are a DSFID (Data Storage Format Identìfìer) representing the format of the data saved ne! remaining memory block specified in ISO / IEC 15961 and ISO / IEC 15962. It is typically 8 bits but can be extended further as specified in the standard. The DSFID consists of 3 fields:

* Access Method, (2 bit)

* Extended Syntax Indicator (ESI), (1 bit)

* Data Format, {5 bit)

The access methods are the fundamental coding rules to compact and format the data.The ISO / IEC 15962 standard provides, in fact, different access methods: (00) No-Directory, (01) Directory, (10) Packed Objects, (11) Data Profiles tag, When the D5FID specifies the access method (10), then the format of the remainder of the User Memory is "Packed Objects". This format maximizes data compression thus minimizing the amount of memory to be stored in the Tags and the amount of data exchanged in the air, at the cost of a higher coding complexity. The Packed Objects mechanism offers advantageous performance and functionality to the IS / IEC 15962: 2004 as it is planned to incorporate it in the next version of ISO / IEC 15962 expected in 2012.

The ESI bit indicates the presence or absence of a second byte of DSFID while the Data Format field represents the Packed Objects format and coincides, according to the RFC3061 standard, with the URN notation field. Packed Objects encoding consists of an Application interface (Al) sequence that includes one or more compacted name-value pairs.

As can be seen from the history of art, there is no reference to data structures that conceive a set of RFID tags with the purpose of "virtual communication channel", nor the possibility of creating more co-net of RFID readers that exchange between their data using the aforementioned communication channel similarly to what happens with other short-range communication technologies, such as Bluetooth, ZigBee, WiFi, etc. The basic idea of the invention is born from this starting point.

DESCRIPTION OF THE INVENTION

Yes, consider an environment in which there are N Reader and M RFID Tag of type EPC Class 1 Gen2. Of these NI RFID Readers, some of class A (hereinafter referred to as Master) and the remaining class B (hereinafter referred to as ALE Client Reader) are required. Class A Reader means a device of greater logic and hardware complexity, often characterized by several communication interfaces (RFID, IEEE 802.11, IEEE 802.3, UMTS, Bluetooth, etc). On the other hand, a Class B Reader is defined as a device with minimum logic and hardware complexity, mainly characterized by basic operations such as reading and writing on Tags by means of the single RFID communication interface. Furthermore, a superior Master Control entity (MC) is defined with which the Masters will interact by means of one of the alternative interfaces to the RFSD one for (managing their own addresses {Fig. 3). The Master Control is a server device to which the Masters are associated via their IP address or MAC address, according to one of the most common connectivity standards (IEEE 802.11, IEEE 802.3, Bluetooth, etc.). The logic of addressing and synchronization via IP address or MAC address is therefore delegated to the connectivity standard available on the Master. The added value of the Master Control defined in this invention is to issue to each Master a unique sequential 5-bit address, hereinafter referred to as Master ID, in order to optimize resources and data storage procedures on RFID tags. The Master Control then performs a NAT (Network Address Translation) operation from IP or MAC address to Master ID.

Each Master defines one or more RAN (RFID Area Network), that is a set of ALE Client Reader and RFID Tag, of which the Master is the coordinator for the implementation and management (the RAN is equivalent to a WPAN in the case of Bluetooth or a WLAN in the case of IEEE 802.11). The ALE Client Readers and RFID Tags will not belong to a RAN exclusively, i.e. they may belong to several RANs coordinated by the same or different Master (Fig. 4). This choice leaves room for future implementations, such as the possibility of differentiate the RANs based on the type of traffic exchanged.

Dì scove ry Tables are defined in the Masters and ALE Client Readers through which the RFID Tags are known that a Master can use as a communication channel to transfer data to an ALE Client Reader and vice versa within a RAN. To this end, the RFID Tag must be structured in an appropriate way, in particular its User Bank. In addition to the standard 150 / IEC 15962, which already governs the encoding and decoding of the User Bank, the method of compression and training of the Packed Objects is considered.

Yes, it therefore defines a new Packed Object and a new AFI (Application Family Identifier -ISO / IEC 15961). Through these new data structures, the Master and the ALE Client Readers manage the phases of:

to. Addressing (Addressing Phase)

b. Communication (Communication Phase)

c. {Control Phase} control

These three phases embody the general functioning of the proposed method. Before proceeding with their description, a new AFi, a new Packed Object and the new Discovery Table data structure are defined.

the proposed method provides full compatibility with the EPC Class 1 Gen 2, Si standard

in fact, they use, as a prerequisite, some memory fields already standardized for which

they need appropriate settings And in particular, for the EPC Bank {Fig. 5}:

* User Memory Indicator (UMI) - 1 bit. If equal to "1" It indicates that Bank 11 is present

and contains data. If it is equal to "0" and is Bank 11 decimal bits ranging from 3 to 7 are

equal to "00000" (Data Format field) then Bank 11 is present but does not initialize;

if it is equal to "0" without Data Format, then Bank 11 is not present. The proposed method requires the presence of Bank 11.

* Toggle - 1 bit. A distinction is made between EPC global applications (bit "0") and ISO applications (bit

"1"), The proposed method is to support ISO applications.

* Attribute / AFI - 8 bit. If the Toggle bit is equal to "1", the EPC bank contains a defined AFI

according to ISO 15961 and an Individuai Unique Identity. If the Toggle bit is, on the other hand, equal to

"0", then the EPC bank contains Attribute bits and an EPC Code, the proposed method

requires the definition of a new AFI, AFI = 24 binary fin 00011000) [Fig. 6).

For TID Bank (Fig. 7):

* User Memory Size - 16 bit. It is defined as the number of 16-bit words in the User Bank.

Starting from this value, we define Fig. 8, where n is a multiplier which, like

we will see later, it will allow to adapt the new Packet Object according to the

size of the User Bank.

For the User Bank (Fig. 9):

â € ¢ Data Storage Format Identifìer (DSFID) - 8 bit. When the DSFID specifies the method

access (10), then the format of the remaining part of user memory is of type

Packed Objects. This is precisely the access method used. The third bit is Indica

the Extended Syntox indicator, which in this case is equal to "0". The last 5 bits

*** â € ”wiWJUW <li> and" "i <ΊJ> 4U W <MÃŒ> n <i> 1 <i> i» ..- finally define the Data Format: (i) "00000" in the in case the User Bank is not

initialized, (ii) "11000" in the new User Bank case encoded for "Communìcation Channel" {Data Format 24). ultimately, the new DSFID is

10011000 while Sa new ISO / IEC 15961 Format 24 table is shown in Fig 10.

The table shows how a block of Al, characterized by the multiplier n, yes

repeats. This block is called a Cluster Packed Object (CPO). According to the

size of the User Bank, the associated multiplier n is identified and therefore the

CPO number (blocks of Al) to be used for coding (Fìg, 11). the CPO is therefore considered a frame and the Packed Object a multi-frame structure.

The Al of the new Packed Object defined are considered in detail;

to. Cluster Map (CM) - 1 * n bit, It consists of a variable number of bits according to the size of the User Bank. A CPO is associated with each bit. If the bit is "1", then it means that the CPO is already used, otherwise it is available for writing. Each bit of the CM refers to a previous offset, that is, it indicates the start of the CPOs concerned.

b. Priority level (PI) - 2 * n bit. Up to 4 priority levels can be defined for each CPO. Only 3 priority levels are used, reserving the last level for future implementations (Fig. 12):

â € ¢ Priority Level 1 {00}: indicates a low priority;

* Priority Level 2 {01): indicates a medium priority;

â € ¢ Priority Level 3 (10): Indicates a high priority;

* {11): for future implementations.

c. ID Reader Sourse (IDRS) - 5 bit. Identification of the source readers which could coincide with a "Master ID" or with a previously assigned "Reader Address Lease".

d. ID Reader Destination (IDRD) - 5 bits. Identification of the recipient Reader (IDRD = 11111 means that the message is broadcast) which could coincide with a "Master ID" or with a previously assigned "Reader Address Lease".

And. ID RAN (IDRAN) - 2 bits. RAN identifier.

f. Count Success (CS) - 4 bit. Success counter read operations.

g. Count Insuccess (CI) ** 4 bit. Counter of failed read operations.

h. Sequence Number (SM) - 5 bits. Sequence number of the packet (SN = 00000 means that the packet has not been segmented but is unique).

ì. Reader Address Lease (RAL) - 5 bits, I move Reader address released by a Master for its RAM sequentially.

j, ID Master (IDM) - 5 bits. Identification of the Master issued by a higher entity (Master Control) to which the Master is connected through one of its interfaces,

k. ID RAN Lease (IDRANL) - 2 bit, identifier of the RAN, It is different from IDRAN in that, as we will see later, they can compete in different management phases.

I Reservation Bits (RB) - 2 bits. Pair of bits that allows you to manage Reader-Tag-Reader addressing;

â– 00: Reader Address Lease has not been assigned; this value will be present in the Discovery Table of a Master;

* 01: the Reader Address Lease has been assigned; this value will be present in the Discovery Table of a Master;

* 10: the Reader Address Lease has been acquired; this value will be present in the Discovery Table of an ALE Client Reader;

* 11: the memory occupied by the triple "Reader Address Lease" - "ID Master" - "ID RAN Lease" is made available for other Masters.

m. Check bit {CB) - 2 bits. Pair of bits that allows, as we will see in the control phase defined below, to update the Discovery Tables in the event that a Master or an ALE Client Reader are no longer available:

* 00: the Discovery Table update mechanism is not taken into consideration;

* 01: Route control is required on the Discovery Table on the initiative of the Masters;

* 10: It is required to check the route on the Discovery Table on the initiative of the ALE Client Reader;

* 11: for future implementations.

n. Payload (PL) - 76 bits. Exchange data between Readers.

Finally, the Discovery Table present on each Master or ALE Client Reader is defined (Fig. 13). This new data structure will be the analogue of a "routing table" for the paths from the Masters to the ALE Client Reader and vice versa. ID Tag is the 96-bit identifier (any other dimension considered is indifferent to the proposed method) of the RFID Tag that is obtained directly from the EPC Bank. It is important to consider this field as a Master could extend his RANs on different RFID Tags. The Discovery Table is stored inside the Readers, as it is assumes that the memory of the Tag is reduced.

ADDRESSING PHASE

In this phase the Master initializes the RFID tags (if they were not already initialized) to manage the addressing phase. Through this phase, in fact, the Discovery Tables of the Master and the ALE Client Reader are "populated", making it possible to define one or more RANs for each Master as well as, for the same RAN, to define multiple paths of the data exchanged between the same pair Master - ALE Client Reader (through the use of different RFID Tags). Only some Al of the CPO are taken into consideration for the initialization of the RAM and the management of the addresses inside it, and in particular;

* Reader Address Lease

* Master ID

* ID RAN Lease

* Reservation Bits

Operation by sequential steps is shown below:

1) The Master receives a unique address (/ D Master) from the nearest Master Control.

2) The Master queries the RFID Tags present in its coverage range by verifying the UMI:

* if UMI = 1, Toggle = 1 and AFI = 00011000, step 4 and step 5 are omitted (the structure is already initialized);

* if UMI = 0 and the bits [3: 7] of the DSFID are "00000" (that is, it is the first Master that writes on the Tag), set Toggle = l and AFI = OOOHOOO and proceed with the following steps;

* if UMI = 0 and the DSFID does not exist, then the RFID Tag has no User Bank and the next Tag is analyzed (if available);

* if UMI = l and Toggleâ ‰ l or AFIâ ‰ 0001100Q, the Tag can be reused as a communication channel (if not password protected) by setting UMI = 0, Toggle -1 and AFI = 00011000 and proceeding with the following steps; if password protected, the next Tag is analyzed (if available).

3) the Master queries the User Memory Size of the TID Bank to find out how many CPOs are available to use (and therefore the range of Al) on the basis of the Packed Object ISO / IEC 15961 Format 24. Therefore, the multiplier n is identified. possible to know the Al to use for the Tag. For example for 512 bits, n = 4 and Ai [0:52].

4) the Master initializes the Packed Object fields: "Cluster Map", "Priority Level" ID Reader Source "ID Reader Destinationâ €, ID RAN", "Count Success", "Count Insuccess' â € ̃Sequence Number", "Reader Address Lease ", ID Master", ID RAN Lease "," Reservation Bìts "," Check Bit "," Payload "and" Bit unused "where required. All the fields that are not of interest in this phase remain only initialized, while the others ("Reader Address Lease", <,> ID Master "," ID RAN Lease "" Reservation Bits ") are defined below.

5) The Master sets UMI = 1,

6) The Master releases sequential addresses in "Reader Address Lease", for its RAN "ID RAM Lease" by entering the value "00" as "Reservation Bits", for the relevant Tag (this entry is stored both in the Tag and in the Master's Discovery Table). The ALE Client Reader (or another Master] that reads the Tag, after aligning itself with the CPO number to be used by also performing step 3, checks that the "Reservation Bits" is "00" and if it is ̈, extrapolate the AI "ID Master", "Reader Address Lease" and "ID RAN Lease", check whether or not it already belongs to the RAN of that Master for that Tag and, if not, update its Discovery Table inserting "10" as "Reservation Bits", while on the Tag the value of "Reservation Bits" will be changed to "01" (Fig. 14).

7) The Master intervenes periodically to check the AL management of the addresses and verifies if the "Reservation Bits" is equal to "01" thus updating its Discovery Table and releasing a subsequent address {then updates the "Reservation Bits again "to" 00 "). When he verifies that on the Tag his triple "Reader Address Lease" - "ID Master" - "ID RAN Lease" has not been read and therefore modified for a certain time, he can decide to release the resource by inserting in the respective Al " Reservation Bits "the value" 11 ". the "Reservation Bits" field is updated to "11" also in the Discovery Table, so that the relevant entries of the Discovery Table can be proposed again at a later time stage.

COMMUNICATION PHASE

In this phase, the tag is read and written for the exchange of information between the Master and the ALE Client Reader. First of all, it is necessary to distinguish between unicast and broadcast communication. Unicast communication means an exchange of messages addressed by the Master to a single ALE Client Reader, which for each message received will free the relative resource used on the RFID Tag as an acknowledgment mechanism. Since the exchange of the same message is likely to occur on more than one Tag, then the ALE Client Reader may have to free up the resources on more than one Tag. Broadcast communication means, instead, an exchange of messages addressed by the Master to all possible ALE Client Readers that are listening to the same Tag. In this case, following the reading operation by each ALE Client Reader, it is not possible to release the relative resource as in the case of unicast communication (it is not known who will have to read the message yet). For this purpose, an algorithm, Memory Resource Management [MRM) is defined which will check suitable "counters" and will mark the rereading times of the ALE Client Reader. The MRM will deal with the release of the communication resources (ie the Tags) even in the case in which a Master has to write information on an already saturated Tag, introducing the concept of. Verified that Toggle = l and AFI = 00011000, both Master and ALE Client Readers control the UML The components of the proposed system vary behavior according to the following cases:

A. UMI = 1 and Master

B. UMI = 0 and ALE Client Reader

C. UMI = 1 and ALE Client Reader

The case "UMI = 0 and Master" is implicitly considered during the addressing phase. A. UMI = 1 and Master, the Master proceeds as follows:

1. Query the User Memory Size of the TID Bank to find out how many CPOs are usable (and therefore the range of Al) based on the Packed Object 150/1 EC 15961 Format 24. Once the multiplier n has been identified, the Al is known to be used for the Tag. For example for 512 bits, n = 4 and Al [0:52].,

2. Check if one of the bits of the CM is set to "0", so as to be able to write to the associated CPO, that is, Al (0) occurs. Considering n = 4, if for example A (0) = 1101 occurs, this implies the possibility of writing on the third CPO. Furthermore, the priority of the message is set, choosing from the 3 available (Priority Level 1, Priority Level 2, Prìority Level 3). In the case of broadcast communication, Priority Level 3 will always be considered.

3. Defines the fields of the CPO (initialization has already occurred in the addressing phase):

"ID Reader Sourceâ €, ID Reader Destination", ID RAN ", Count Success" Count Insuccess "Sequence Numberâ € and" Bit unused "where required.

4. If the CM is made up of only "1" it is necessary, instead, to use the MRM algorithm for the eventual release of the resources. In fact, each bit of the CM corresponds to 2 bits of the PL which distinguish its priority. If the message that the Master wants to write has a strictly higher priority than one of the priorities identified by the PL, then the relative CPO will be engaged by updating the "Priority Level", otherwise the "NoWriteAccess" message will be returned (Flg. 15). Obviously, it does not replace the first CPO with lower priority but the CPO with the absolute lowest priority. Neither! in the case of equal lower priorities, the decision is made to release the CPO with the highest CI value.

5. Although the MRM algorithm provides for a gradual release of resources ensuring fairness, it is possible for a Master to increase the priority of the message whenever the "NoWrìteAccess" message is received.

B. UMI = 0 and ALE Client Reader. The RFID Tag does not have the User Bank, in which case the message "UserMemoryEmpty" will be returned to the ALE Client Reader (Fig. 15).

C. UMI = 1 and ALE Client Reader. Proceed as follows:

1. The ALE Client Reader interrogates the User Memory Sìze of the TID Bank to know how many CPOs can be used [and therefore the range of Al) on the basis of the Packed Object ISO / IEC 15961 Format 24. The multiplier n has been identified , It is possible to know the Al to use for the Tag. For example for 512 bits, n = 4 and Al [0:52].

2. The ALE Client Reader queries the AI (0} to obtain the Cluster Map and in particular information on which bits are set to "1." The size of the Cluster Map is variable, for example in the case of 512 bits à It consists of 4 bits. If all the bits are set to "0", then there is no information to read and the message "ClusterMapNull" is returned (Fig. 15). If, on the other hand, d are bits set to "1" , then it is necessary to query for each related CPO the Al referring to the IDR. Assuming to have CM = 1011, THIS Client Reader will query Al {3), Al (28), Al (41).

3. Whenever there is no match with the IDRD of each CPO, the message "NoFindIDRD" is returned (Fig. 15). If, on the other hand, the IDRD stored in the Tag coincides with that of the ALE Client Reader, then it is necessary to check the Al "Sequence Numberâ €," ID Reader Source "and" ID RAN "of the related CPOs. Assuming that for Al (3) and for Al (41) there is no matching and instead there is for Al (28), the field Al {32), the field Al (27) and the field Al (29) are interrogated to verify if the ALE Client Reader has already acquired in a previous reading operation the "Payload" identified by that Sequence Number, that Reader Source ID and that RAN ID respectively.

4. The information can be unicast and broadcast. Let's consider a broadcast message. If the information associated with the triple "ID Reader Source" - "ID RAN" - "Sequence Number" has already been previously acquired by an ALE Client Reader, the message "DuplìcatePayload" will be returned {Fig. 15) and the â € œCount Insuccess field will be increased, otherwise the "Payload" field will be queried and the "Count Success field will be increased. Tag because it potentially continues to be

available for other ALE Clients Re ad and r. For example, if the triple AI (27) -AI (29) -AI (32) does

reference to a Payload already acquired, then Al [31) = 0001 (assuming that it was the

second access to the CPO); if instead the triple Al (27) -Al {29} -Al (32) is relative to a new one

Payload, then yes interrogates Al (38) and modifies Al (30) = 0001 (assuming it was the

first access). If, on the other hand, the information is unicast, TALE Client Reader will modify the "0" bit on the CM. So the fields "Count ìnsuccess" and "Count Success" intervene only if the message is broadcast (in Fig. 16 examples of reading successfully).

In the case of a broadcast message, whenever an ALE Client Reader performs a read operation on a CPO that requires the "Count

Insuccess ", it checks if (CS - CI)> 0 through its MRM algorithm

condition is verified, TALE Client Reader will not perform any further operation,

otherwise it will change its bit to "0" on the CM to free up the memory resource on the

£ Tag (in Fig. 17 examples of unsuccessful reading). The same Reader can log in

£ to the User Bank for the same CPO only after a certain amount of time calculated by a

generic algorithm (e.g. the exponential backoff algorithm known in the literature).

r CONTROL (CONTROL PHASE)

is This phase concerns the update of the Discovery Tables, It can be started either by a

Master that from an ALE Client Reader. The phase allows you to check the presence or absence of

a Master and / or ALE Client Reader inside gives a RAN over time and, by implication, also

of a Tag, Yes distinguish the following cases:

A. ALE Client Reader no longer present

B. Master no longer present

C. Tag no longer present

A. ALE Client Reader no longer present. A Master who wants to renew one of his entries on the

Discovery Table sends the triple "Reader Address Lease" - "Master ID" - "ID RAN Lease" with

"Check Bit" equal to "01". An ALE Client Reader that recognizes the triple "Reader Address Lease"

- "ID Master" - "ID RAN lease" present in your Discovery Table, edit on the Tag

"Check Bit" at "00" In order to inform the Masters that it is still present (Fig. 18). If the

Instead, the Master verifies that the "Check Bit" continues to be "01" for a given one

period, then you can decide to deallocate the entries related to that ALE Client Reader from your Discovery Tabi and,

B, Master no longer present. An ALE Client Reader who wants to renew an entry on the Discovery Table sends the triple "Reader à € ddress Lease" - "ID Master" - ID RAN Lease "with" Check Bit "equal to" 10 ", A Master that recognizes the triple "Reader Address Lease" - "ID Master" - "ID RAN Lease" present in your Discovery Table, change the "Check Bit" on the Tag to "00" in order to communicate ALE Client Reader that it is still present (Fìg . 19) If the ALE Client Reader verifies that the "Check Bit" continues to be "10" for a certain period, it can decide to deallocate the entries relating to that Master from its Discovery Table, For each entry of the Discovery In fact, the Table is associated with a time reference managed by the Reader clock (both Master and ALE Client Reader). A lease time is therefore defined for each entry of the Discovery Table which distinguishes its validity; lease time has not expired, no control operations take place for that entry z of the lease time, the relevant entry is checked and the lease time is renewed (in a similar way to what happens with the lease time for the DHCP of Internet networks}.

C Tag no longer present. When a Master or an ALE Client Reader verifies that a Tag is no longer in their operating range, they delete the Discovery entries related to that Tag. A minimum number of queries (Thr) is therefore defined that a Master and / or ALE Client Reader must consider before proceeding with the update of the Discovery Table.

In conclusion, the Addressing and Control phases share the common Al of the Packed Object ISO / IEC 15961 Format 24 therefore they cannot be foreseen at the same time for the same CPO. The Communication phase, on the other hand, is independent and uses Al exclusively, so it can always be associated simultaneously with the Addressing or Comparison phase for the same CPO.However, in general, several phases can be managed simultaneously on different CPOs. of the same RFID Tag,

Claims (1)

Method and system for using RFID tags as a communication channel in an RFID Area Network (RAN) CLAIMS [1] A method for coordinating and synchronizing the exchange of data packets within a communication system consisting of: (i) one or more RFID Readers (Master) of high logic and hardware complexity characterized /) by several interfaces of communication; (ii) one or more RFID Readers (ALE Client Readers) of logical complexity and basic hardware characterized by the RFID communication interface only; (ìil) RFID tags enabled for reading and writing operations; (iv) a server (Master Control) of minimal logic and hardware complexity characterized by several communication interfaces. [2] A method in accordance with claim [1] in which a Master Control server is associated with Master readers, for each of which the Master Control issues a unique address and with which it communicates through the use of a traditional communication such as WiFi, UMT5, Bluetooth, ZigBee. [3] A method according to claim (1] in which a Master reader defines and coordinates one or more RAIM (RFID Area Network), to which a set of ALE Client Reader readers and a set of RFID Tags are associated; each RAIM is conceptually equivalent to a Wireless Personal Area Network (WPAN) in the case of Bluetooth or to a Wireless Local Area Network (WLAN) in the case of IEEE 802.11. [4] A method according to claim [3] in which an ALE Client Reader can be established simultaneously with different RANs both created by the same Master reader and by different Master readers. [5] A method according to claim (3] in which an RFID Tag can be associated simultaneously with different RANs both created by the same Master reader and by different Master readers. [6] A method in accordance with claim [1] in which the exchange of data between the Master reader and the ALE Client Readers belonging to the same RAN is carried out through the use of EPCglobal Class1 Gen2 type RFID tags equipped with user memory block. A method in accordance with claim [3] in which for each Master reader and for each reader ALE Client Reader, in order to reserve and keep updated all the possible paths from a Master reader to an ALE Client Reader and vice versa, is defined and used a Discovery Table structure made up as follows: (i) new address of the ALE Client Reader reader issued by a Master reader sequentially for a given RAN; (li) identification of the Master reader issued in accordance with claim [2] by a Master Control server; (iii) RAN identifier issued in accordance with claim (3] by a Master reader; (Iv) pair of bits for managing the addresses issued by the Master reader to the ALE Client Reader; (v) pair of bits for managing the Discovery Table update; (vi) Tag identifier obtained from the EPC Bank memory block of the EPCglobal EPC Tag Data Standard. [8] A method according to claim [1] in which a new AFI (Application Family Identifier) is defined with a decimal value 24 ", binary value 00011000, and is stored in the EPC bank memory block of the EPCglobaà ¬ EPC Tag Data Standard and used to distinguish the particular method of use of RFID Tags, for which the patent is requested, from other traditional methods of use of Tags (encoded by pre-existing AFI values). [9] A method according to claim [1J in which, in order to store the information necessary for the functioning of the system in the User Bank memory block of the EPCglobaì EPC Tag Data Standard, a new Cluster Packed Object data structure is used defined as consisting of the following fields: (i) identifier of the source reader which can be the identifier of a Master reader or the identifier of an ALE Client Reader; (the) identifier of the recipient reader which could be the identifier of a Master reader, that of an ALE Client Reader, or the broadcast transmission identifier; (iii) identifier of the RAN; (iv) a counter that successfully updates the read accesses for each Cluster Packed Object; (v) a counter that updates the failed read accesses for each Cluster Packed Object; (vi) a numeric field that identifies the sequence number of the exchanged data packet; (vii) the address of the ALE Client Reader issued by a Master reader sequentially for a given RAN; (vili) the identifier of the Master reader; (ix) an identifier of the RAN in accordance with claim [7]; (x) pair of bits for managing the addresses in accordance with claim [7j; (xi) pair of bits for managing the updating of the Discovery Table in accordance with claim [7]; (xii) data packet that you want to exchange between a Master reader and an ALE Client Reader. [10] A method according to claim [9] in which the recipient reader is enabled to exchange both unicast and broadcast traffic. [11] A method in accordance with claim [1] in which, to store the information necessary for the functioning of the system in the User Bank memory block of the EPCglobai EPC Tag Data Standard, a new Packed Object defined as consisting of a variable number of Cluster Packed Objects plus three further fields: (ì) a variable size field called "Cluster Map" which establishes how many Cluster Packed Objects are defined and which of these are free or occupied; (ii) a variable size field that establishes the priority level of each Cluster Packed Object; (iii) a field of unused bits to integrate the data packets being exchanged in order to keep them constant, [12] A method according to claim [9] in which the choice of the number of Cluster Packed Objects is made according to the size of the User Bank memory blocks provided by the EPCglobal EPC Tag Data Standard. [13] A method in accordance with claim [1] in which three operating phases of the system are envisaged: (i) the "addressing" phase for managing the addresses in accordance with Sa claim [7 {, with which ¬ "populate" Se Discovery Table; [li] the "communication" phase in which the data packets are exchanged; (ili) Sa "control" phase in which the Discovery Tables are updated, in accordance with claim [7]. [14] A method according to claim [13] in which the "addressing" step provides that: (i) reader Master and reader ALE Client Reader interrogate the "User Memory Size" field of the TID Bank memory block provided by 'EPCglobal EPC Tag Data Standard in order to align with the number of Cluster Packed Objects to be used in accordance with claim [11]; (ii) reader Master and reader ALE Client Reader access the single memory blocks of each single Cluster Packed Object, in accordance with claims [9] and [11]; (iìi) the pair of bits in accordance with claim [7] is used as an indicator that allows to understand if an address has been assigned to a Master reader, to an ALE Client Reader or has not been assigned; (iv) the Master reader, in accordance with claim [7], releases sequential addresses for a given RAN to be assigned to the ALE Client Readers reachable by means of the RFID lags on which it writes, also updating its Discovery Table, [15] A method according to claim [13] in which the "communication" phase provides that: {i} reader Master and ALE Client Reader interrogate the "User Memory Size" field of the 770 Bank memory block provided EPCglobal EPC Tag Data Standard in order to align on the number of Cluster Packed Objects to be used in accordance with claim [11]; (ii) reader Master and reader ALE Client Reader access the single memory blocks of each single Cluster Packed Object, in accordance with claims [9] and [11]; [iii) reader Master and reader ALE Client Reader interrogate the "Cluster Map" field of the Packed Object to know which Cluster Packed Objects are available for writing and reading operations, in accordance with claim [11]; (iv) a priority level relating to the type of data exchanged is defined for each individual Cluster Packed Object, in accordance with claim [11]; (v) Master reader and ALE Client Reader reader proceed to different functional steps depending on whether the User Bank memory block provided by the EPCglobal EPC Tag Data Standard is present or not, [16] A method in accordance with claim [15] in which yes defines and uses a Memory Reso uree Management protocol for the allocation and deallocation of Cluster Packed Objects based on the number of read operations of the Cluster Racket Object occurred with success, the number of failed read operations of the Cluster Racket Object and the priority levels of the Cluster Packed Objects. [17] A method according to claim [13] in which the "control" step provides that: (i) reader Master and ALE Client Reader interrogate the "User Memory Sìze" de! TtD Bank memory block provided by the EPCglobai EPC Tag Data Standard in order to align with the number of Cluster Packed Objects to be used in accordance with claim [11]; reader Master and reader ALE Client Reader access the single memory blocks of each single Cluster Pack and Object, in accordance with claims [9] and [11]; (iii) the pair of bits according to claim [7] is used as an indicator to distinguish a control procedure started by a Master reader from a control procedure started by an ALE Client Reader.