Methods and apparatuses for selective communication between tag and reader using filter

The present disclosure relates to a method and apparatus for selective communication between a tag and a reader using a filter. According to an embodiment of the present disclosure, a communication method between a tag and a reader using a filter performed by a reader includes generating a filter based on tag information of the tag to collect data, transmitting the generated filter to the tag, and receiving data from a tag that selected through a filtering operation of the transmitted filter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No. 10-2018-0170761 filed on Dec. 27, 2018 in Korea, the entire contents of which are hereby incorporated by reference in their entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a method and apparatus for selective communication between a tag and a reader using a filter.

2. Description of Related Art

A tag in the conventional RFID communication transmits its own identification (ID) only according to a query which is a data transmission request of a reader. Recently, various sensors are attached to Radio-Frequency identification (RFID) tag, and it has been developed a Computational RFID (CRFID) to which energy harvesting and computation functions are added. Owing to this, the CRFID which may perform various things, data and process functions draw attention as one of core device of future Internet of Things (IoT).

In the conventional RFID communication technique, when a reader transmits a query message to collect information of tags, all the tags that receive it transmit data to the reader. The Collision phenomenon that two or more tags transmit data to the reader is an important problem that degrades the performance of an RFID system such as use efficiency degradation of channel and energy, increase of delay time, and the like. Many Media Access Control (MAC) methods have been researched to control such a Collision phenomenon. There is a central control type scheme in which a reader designates directly all tags and determines whether to transmit data. The central control type scheme is not proper for an IoT network environment in which many terminals are disposed since much overhead is required for designating directly load increase of a processing unit for transmission scheduling and many tags. Dynamic Frame Slotted Aloha (DFSA) protocol, which is a distributed type Media Access Control method, is a protocol based on Time Division Multiple Access (TDMA) in which tags selects autonomously a random Time-slot in a predetermined frame size informed by a reader and transmits data. The reader estimates the number of tags that attempt to transmit data at a start of a frame for every data transmission, configures an optimal frame size, and collect data of the tag, which is repeated until data transmissions of all tags are completed.

In the conventional RFID, since a reader needs to collect information of all RFID tags and the number of tags is not so great, the Media Access Control method has been frequently used. However, in a massive IoT network environment including CRFID tag, since the number of tags is great and the tags are not required to receive sensing information of all CRFID tags, it is not proper to apply the conventional DFSA protocol without any change. When a reader uses the conventional DFSA Media Access Control method to collect information of a specific CRFID tag, according to a data transmission request of the reader, all tags attempt data transmission contention. Accordingly, there is a problem that channel resource is wasted owing to the data transmission contention of unwanted tags, and owing to this, throughput is decreased, and delay time is increased.

SUMMARY

Exemplary embodiments of the present disclosure are to provide a method and apparatus for selective communication between a tag and a reader using a filter, in a network environment that a reader collects data of a tag (e.g., CRFID tag) and transmits it to a server according to the request of the server (e.g., IoT management server), in which the reader may selectively collect only the data of specific tag requested by the server.

Exemplary embodiments of the present disclosure are also to provide a method and apparatus for selective communication between a tag and a reader using a filter, in which a tag receives a filter (e.g., hash function filter) having a property of returning a unique index from a reader and determines whether to transmit data using the received filter.

Exemplary embodiments of the present disclosure are also to provide a method and apparatus for selective communication between a tag and a reader using a filter, to compensate the phenomenon that unwanted tag may pass a filter in the case that the filter is generated using a single hash function, which can minimize a filtering error by generating a filter using a plurality of hash functions.

According to one example embodiment of the present disclosure, it is provided a communication method between a tag and a reader using a filter performed by a reader including generating a filter based on tag information of the tag to collect data; transmitting the generated filter to the tag; and receiving data from a tag that selected through a filtering operation of the transmitted filter.

The step of generating a filter may include generating the filter using at least one hash function.

The step of generating a filter may include determining filter generation information required for generating the filter based on tag information to collect, and generating the filter using the tag information and the determined filter generation information.

The step of generating a filter may include determining the filter generation information including a filter length, a random-number generation seed and a number of hash functions.

The step of receiving data may include estimating a number of remaining tags that do not transmit data based on a number of slots in which collision occurs.

Meanwhile, according to another embodiment of the present disclosure, it is provided a communication method between a tag and a reader using a filter performed by a tag including receiving a filter from a reader; checking whether to pass through the filter based on the received filter and its own tag ID; and when passing through the filter, transmitting data to the reader.

The method may further include operating in a sleep mode when failing to pass the received filter.

The step of checking whether to pass through the filter may include transforming its own tag ID to an index value and checking whether to pass through the filter according to a position value corresponding to the transformed index value in the received filter.

The step of checking whether to pass through the filter may include transforming its own tag ID to an index value and check whether to pass through the filter according to at least one position value corresponding to the transformed at least one index value in the received filter.

The step of transmitting data may include selecting a transport slot randomly within a frame length and transmitting data to the selected transport slot.

Meanwhile, according to another example embodiment of the present disclosure, it is provided a reader for a selective communication between a tag and a reader using a filter including a communication module configured to communicate with a tag; a memory configured to store at least one command; a processor connected to the communication module and the memory, by executing at least one command, wherein the processor configured to: generate a filter based on tag information of the tag to collect data; transmit the generated filter to the tag; and receive data from a tag that selected through a filtering operation of the transmitted filter.

The processor may generate the filter using at least one hash function.

The processor may determine filter generation information required for generating the filter based on tag information to collect and generate the filter using the tag information and the determined filter generation information.

The processor may determine the filter generation information including a filter length, a random-number generation seed and the number of hash functions.

The processor may estimate the number of remaining tags that do not transmit data based on the number of slots in which collision occurs.

Meanwhile, according to another embodiment of the present disclosure, it is provided a tag for a selective communication between a tag and a reader using a filter including a communication module configured to communicate with a reader; a memory configured to store at least one command; a sensing module configured to sense data; a processor connected to the communication module, the memory and the sensing module, by executing at least one command, wherein the processor configured to: receive a filter from a reader; check whether to pass through the filter based on the received filter and its own tag ID; and when passing through the filter, transmit data to the reader.

The processor may operate in a sleep mode when failing to pass the received filter.

The processor may transform its own tag ID to an index value and check whether to pass through the filter according to a position value corresponding to the transformed index value in the received filter.

The processor may transform its own tag ID to an index value and check whether to pass through the filter according to at least one position value corresponding to the transformed at least one index value in the received filter.

The processor may select a transport slot randomly within a frame length and transmit data to the selected transport slot through the communication module.

According to exemplary embodiments of the present disclosure, when a reader collects data of a tag (e.g., CRFID tags), only information of required tags may be collected without overhead of the central control scheme.

Through this, according to exemplary embodiments of the present disclosure, energy of tags that do not participate in data transmission contention can be efficiently utilized in comparison with the technique applied to the conventional RFID system.

According to exemplary embodiments of the present disclosure, a channel use efficiency for data transmission can be increased by about 30%, and further, a time for collecting information of all tags can be decreased by about 40%.

The present disclosure may have various modifications and various embodiments and specific embodiments will be illustrated in the drawings and described in detail in the detailed description.

However, this does not limit the present disclosure to specific embodiments, and it is understood that the present disclosure covers all the modifications, equivalents and replacements included within the idea and technical scope of the present disclosure.

Terms including as first, second, and the like are used for describing various constituent elements, but the constituent elements are not limited by the terms. The terms are used only to discriminate one constituent element from another component. For example, a first component may be referred to as a second component, and similarly, the second component may be referred to as the first component without departing from the scope of the present disclosure. A term ‘and/or’ includes a combination of a plurality of associated disclosed items or any item of the plurality of associated disclosed items.

When it is described that a component is “connected to” or “accesses” another component, the component may be directly connected to or access the other component, or a third component may be present there between. In contrast, it is understood that, when it is described that an element is “directly connected to” or “directly access” another element, it is understood that no element is present between the element and another element.

Terms used in the present application are used only to describe specific embodiments and are not intended to limit the present disclosure. A singular form may include a plural form if there is no clearly opposite meaning in the context. In the present application, it should be understood that term “include” or “have” indicates that a feature, a number, a step, an operation, a component, a part or the combination thereof described in the specification is present, but does not exclude a possibility of presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof, in advance.

Unless it is contrarily defined, all terms used herein including technological or scientific terms have the same meanings as those generally understood by a person with ordinary skill in the art. Terms which are defined in a generally used dictionary should be interpreted to have the same meaning as the meaning in the context of the related art and are not interpreted as an ideal meaning or excessively formal meanings unless clearly defined in the present application.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings and in describing the preferred embodiments with reference to the accompanying drawings, the same reference numeral will refer to the same or corresponding component regardless of the reference numeral and a duplicated description thereof will be omitted.

FIG. 1is a diagram for describing IoT network environment to which an embodiment of the present disclosure is applied.

As shown inFIG. 1, in heavy traffic massive IoT network10, CRFID tags100are congested massively, collect various IoT information such as a temperature, a humidity, a pressure, an intensity of light, and the like, and transmit data to CRFID reader200.FIG. 1shows a configuration example of the IoT network10including CRFID tags100. Each of tags100performs functions of energy harvesting, sensing and computing, and communication. The reader collects information from the tag100according to a request of an IoT management Server300and transmits information desired by the IoT management Server300selectively.

It is assumed that the IoT network10to which an embodiment of the present disclosure is applied includes the IoT management Server300, the reader200that performs a communication with the IoT management Server300and collects sensing data of the tag100and a plurality of CRFID tags100that collect information from various sensors in the tag. The IoT management Server300present in an exterior network may be connected to the reader200in wired and wireless manner. The Server300informs data type to collect and unique IDs of the CRFID tags for collecting the corresponding data to the reader200. The reader200performs the role of collecting the information requested by the Server300from the tag100and forwarding it to the Server300. The reader200is located at the center of the network10and collects information of a plurality of CRFID tags100which is uniformly disposed with the reader200at the center.

FIG. 2is a diagram for describing a selective data collection process between a tag and a reader in the IoT network environment to which an embodiment of the present disclosure is applied.

An embodiment of the present disclosure relates to a network environment in which the reader200collects information of the CRFID tag100according to the request of the IoT management Server300and transmits it to the IoT management Server300. The reader200may selectively collect only the data of specific CRFID tags101requested by the IoT management Server300.

For this, in an embodiment of the present disclosure, a hash function is used. A hash filter function in an embodiment of the present disclosure has the property of returning a unique index. Through the filter transmitted by the reader200, the CRFID tags101,102and103that receive it may determine whether it is available to transmit. As shown inFIG. 2, a specific CRFID tag101among the CRFID tags101,102and103that receive the filter may transmit Specific IoT service data to the reader200through the filter. On the other hand, the filtered CRFID tag102that fails to pass the filter does not transmit data to the reader200. Here, an unwanted tag103may pass the filter and transmit unwanted IoT service data to the reader200. To compensate the problem that an unwanted tag passes a filter in the case that the filter is generated using a single hash function, the embodiments of the present disclosure may minimize a filtering error by generating a filter using a plurality of hash functions.

The embodiments of the present disclosure may be divided into a phase for the reader200generates a filter for collecting data requested by the IoT management Server300, a phase for the reader200transmits the generated filter information to the CRFID tags101,102and103and the CRFID tags101,102and103acknowledge whether the data is transmitted through the filter, and a phase for the CRFID tags101,102and103transmit data to the reader200.

Before the reader200collects data, the reader200generates a filter based on a unique identification (ID) of the tag, a length of hash function filter and random-number generation seed information. To generate a filter, the IoT management Server300transmits unique IDs of the CRFID tags101,102and103to collect data and the total number of tags in a network to the reader200. The reader200that identifies the corresponding information determines a length of the hash function filter according to the total number of tags. Later, the reader200determines a random-number generation seed value and transforms a unique ID of each tag to a specific index value. In this case, as the length of the generated filter is short, the overhead of the filter generation and transmission is decreased. However, in the case that the length of filter is shorter than the number of tags101,102and103, since the ID of each tag does not have a unique value, the probability that unwanted CRFID tag103passes the filter increases. Accordingly, the length of filter needs to be determined to be equal to or greater than the total number of tags.

FIG. 3is a diagram for describing data transmission process according to an embodiment of the conventional art and the present disclosure.

The conventional data transmission process includes a part that the reader transmits a query message to the CRFID tags and a part that the CRFID tags transmits data to the reader.

On the contrary, in an embodiment of the present disclosure, the data transmission process is divided into two steps including a first phase and a second phase. The data transmission process includes a first phase that the reader200identifies IDs of specific CRFID tags, generates a filter and transmits the filter to the tags according to a request of the IoT management server300and a second phase that the tags receiving the filter determine whether to transmit and transmit data by participating a data transmission contention.

As such, the data collection according to an embodiment of the present disclosure is divided into two phases. The first phase is a phase of generating a filter and identifying whether to perform filtering of the tag by a specific data request of the IoT management server300, and the second phase is a data transmission phase of the tags that pass through the filter. In the phase of generating a filter and identifying whether to perform filtering of the tag, the reader200computes the unique ID owned by the tag to a specific index through the hash function and makes filter based on it. The reader200may transmit the filter to the tags, and each of the tags that receives it may compare the index computed through its own unique ID with the index of filter and identify whether to transmit data. In the data transmission step, only the tags that selected through a filtering operation of the filter transmit data to the reader, and the tag that does not transmit data is switched to a sleep mode in the corresponding phase. According to an embodiment of the present disclosure, a delay time may be decreased as well as the channel resource and energy use efficiency are improved in the CRFID IoT network environment.

FIG. 4is a diagram for describing an example of a process for a reader to generate a filter according to an embodiment of the present disclosure.

In an embodiment of the present disclosure, the hash function H for a filter receives an input of a length l of filter, a random-number generation seed r and a unique ID of tag and returns an index in a uniform distribution within the length of filter. Using a plurality of random-number generation seeds, several indexes may be returned for an ID of a tag, and accordingly, an error that may occur in a single hash function is controlled.

FIG. 4shows an example for the reader to generate a filter. For example, a wireless network includes 6 tags, and the IoT management server300forwards unique ID information of tag1, tag2and tag4to the reader200to collect data of tag1, tag2and tag4. The reader200determines the length of filter to 6 bits based on the total number of tags in a network and transform the unique IDs of tags1,2and4to index values through the hash function. When the unique ID of tag is transformed to an index value i, the ithbit of the filter is set to 1. Through this, the reader200generates the filter based on the result of collecting the index values of tags1,2and4. Tags1,2and4that receive the filter transform their own unique IDs to index values with the received length of filter and random-number generation seed value and determines whether to transmit and receive data based on the filter information.

In a network including massive tags, in the case that the reader200set the length of tag to equal to or greater than the number of tags for a normal operation of the filter, the performance may be degraded owing to the overhead occurred for generating and transmitting the filter. In this case, the reader200uses a plurality of hash functions to generate the filter, and the probability that an unwanted tag transmits data through the filter is decreased when the length of filter is smaller than the number of tags.

FIGS. 5A-5Care diagrams for describing examples of an operation for a reader which generates a filter using a plurality of hash functions according to an embodiment of the present disclosure.

In the case that a filter is generated using N hash functions, the reader200generates N random-number generation seeds and transforms unique IDs of tags into N index values for each seed. Accordingly, when the number of total tags is T, the reader generates a filter by collecting NT index values. The tag that receives the filter transmits data only in the case that all the N index values generated with their own unique IDs utilizing N seed values are identical to those of the filter, but in the case that even one of them is not identical, the tag dos not transmits data.

Accordingly, when a plurality of hash functions is used rather than a single hash function is used, the probability that unintended tag passes through a filter may be decreased.FIG. 5Ashows an example of using a single hash function, andFIG. 5BandFIG. 5Cshow examples of the cases that the number of hash functions is 2 and 3, respectively. However, in the case that too many hash functions are used, most of values of a filter becomes1and the filter is unable to not perform a normal role. Accordingly, the reader200needs to determine a proper number of hash functions used for generating a filter according to the total number of tags and the length of filter.

A ratio of the number Tunintendedof unintended tags that pass through a filter and transmit data and the number Tintendedof tags to collect is defined as Equation 1 below as a performance indicator EC-ration.

FIG. 6is a diagram for describing a relation between the number of hash functions used for generating a filter and EC-ratio according to an embodiment of the present disclosure.

FIG. 6is a graph showing a relation between the number of hash functions used for generating a filter and EC-ratio while the length of filter is changed to 25, 26, 27and 28. At this time, the total number of tags in a network is 100, and a ratio ϕ of a tag intended to collect data in the entire tags. In the graph, as EC-ratio, which is the performance indicator, is small, which means that data transmission rate of the unintended tag is low. Since the number Tunintendedtags is small as the length of filter is increased, a small EC-ratio value is output, and it is identified that a small EC-ratio value is output when two or three hash functions are used for generating the filter.

FIG. 7is a diagram for describing an operation process in a protocol between a tag and a reader according to an embodiment of the present disclosure.

The first phase is an additionally generated phase in the conventional DFSA process, in which the reader200generates a filter and the tag determines whether to data through the information of the filter. The IoT management server300transmits a unique ID of the tag intended to collect by the reader and information of the total number of tags in a network, and the reader200generates the filter based on the corresponding information. The reader200broadcasts the number of hash functions used for generating the filter, a random-number generation seed value and the filter including the length information of the filter to the tags. The tag determines whether to transmit and receive data based on the received information.

The tags that pass through the data filter in the first phase participate in a contention for data transmission in the second phase. As an example, tag1, tag3and tag5are tags that pass through the filter in the first phase, and tag2, tag4and tag6are tags that fail to pass through the filter in the first phase. The tags that fail to pass through the filter harvest energy through the signal sent by the reader200in the second phase. In the second phase, the tag transmits data to the reader200through a communication of the conventional DFSA scheme. The reader200may determine the total number of tags in a network received from the IoT management server300and a size of a first frame identically in the first phase. The reader200may determine a size of a next frame based on the number of slots in which collision occurs in a previous frame.

FIG. 8is a diagram for describing a system efficiency performance according to the number of tags in the conventional art and an embodiment of the present disclosure.

To evaluate the performance of the conventional art (conventional) and an embodiment of the present disclosure (proposed), a system efficiency and a data throughput performance are compared through a simulation. The system efficiency means the number of tags that succeed in a transmission in the first frame among the tags that attempt to collect data, shows good performance as the value increases. The data throughput means the number of total slots that pass until all tags succeed in a transmission and shows good performance as the value decreases. The conventional scheme includes only the second phase in which the reader collects data of all tags without the first phase which is proposed in an embodiment of the present disclosure.

FIG. 8is a graph showing a system efficiency performance according to the number of tags when a size of the first frame is changed to 50, 150 and 250. When the number of tags is smaller than the size of the first frame, since the channel use rate increases as the number of tags becomes greater, the system efficiency is improved. However, in the case that the number of tags becomes greater than the size of the first frame, since the probability that collision occurs increases as the number of tags becomes greater, the system efficiency is degraded. In an embodiment of the present disclosure, the number of tags that attempt a contention in the first frame becomes smaller than the conventional scheme by using the filter, the maximum system efficiency is better. In the conventional scheme, the system efficiency has a maximum value when the total number of tags and the size of the first frame is identical. However, in an embodiment of the present disclosure, since not all tags attempt a transmission, it is identified that the system efficiency has a maximum value when the number of tags that pass through the filter is identical to the size of the first frame.

FIG. 9is a diagram for describing a data throughput performance according to the number of tags in the conventional art and an embodiment of the present disclosure.

FIG. 9is a graph showing a data throughput performance according to the number of tags when a ratio ϕ of tag to collect is 0.2 and 0.4, the number of hash functions used for generating a filter is set to 1 (# hash function=1) and 2 (# hash function=2). The data throughput performance is represented by Total number of time slots. In an embodiment of the present disclosure, since the number of tags that participates in a contention for data transmission is decreased by using a filter, it is identified that the data throughput performance is greater than the conventional scheme (conventional). In addition, as the ratio ϕ of tag becomes smaller, better performance is output, since a gain becomes greater caused by controlling a plurality of unwanted tags from participating in data transmission contention through a filter. In the case of having the same ratio of ϕ tag value, better performance is output, since malfunction probability of the filter becomes decreased when two hash functions are used rather than one hash function is used for generating the filter.

An embodiment of the present disclosure may be applied to the scenario in which the information required in a network including various types of massive IoT devices is quickly collected and applied to the scenario in which a network including UEs that requires low power operation is permanently maintained since UEs that do not participate in data transmission may harvest energy.

Meanwhile, an embodiment of the present disclosure relates to a method for a reader to collect only data of a specific CRFID tag wanted by an IoT management server through a filter using hash function in a massive Internet of Things (IoT) environment including a Computational RFID (CRFID) tag to which a computation function is added to a Radio Frequency identification (RFID) tag. Hereinafter, with reference toFIG. 10toFIG. 13, it is described a selective communication method between a tag and a reader using a filter according to an embodiment of the present disclosure.

FIG. 10is a diagram for describing a selective communication method between a tag and a reader using a filter according to an embodiment of the present disclosure.

In step S101, the server300selects data to collect in the server300.

In step S102, the server300transmits information of a tag100to collect the corresponding data to a reader200.

In step S103, the reader200determines a length of a filter, a random-number to be used for a filter generation and the number of hash functions.

In step S104, the reader200generates a filter based on the determined length of a filter, the random-number to be used for a filter generation and the number of hash functions.

In step S105, the reader200transmits information required for the filter generation and the filter to the tag100.

In step S106, the tag100that receives the corresponding information transforms its own unique ID to an index value.

In step S107, the tag100checks whether the corresponding index position value of the filter is 1.

In step S108, when the corresponding index position value is 1, the tag transmits the data.

In step S109, the reader200transmits the collected data to the server300.

In step S110, when the corresponding index position value is not 1, the tag100operates in a sleep mode.

FIG. 11is a diagram for describing a process of transmitting data in a selective communication method between a tag and a reader according to an embodiment of the present disclosure.

In step S201, the reader200determines a length of frame.

In step S202, the reader200transmits the corresponding frame length information to the tag100as a query message.

In step S203, the tag100determines a slot to transmit data randomly in a frame.

In step S204, the tag100checks whether the slot is for a data transmission.

In step S205, when the slot is not for a data transmission, the tag100waits for a next slot.

In step S206, when the slot is for a data transmission, the tag100transmits data.

In step S207, the tag100checks whether the data transmission is successful.

In step S208, when the data transmission is not successful, the tag100waits for a next frame.

In step S209, the reader200determines a next frame length by estimating the number of remaining tags with the number of collision slots after step S208and performs steps from step S202.

In step S210, when the data transmission is successful, the reader200checks whether a current frame is ended.

In step S211, when the current frame is not ended, the reader200collects data until the current frame is ended from tag100.

In step S212, when the current frame is ended, the reader200checks whether the number of collision slots in the corresponding frame is 0.

In step S213, when the number of collision slots in the corresponding frame is not 0, the reader200determines a next frame length by estimating the number of remaining tags with the number of collision slots.

In step S214, the reader200starts a next frame after step S213.

Meanwhile, when the number of collision slots in the corresponding frame is 0, the reader200terminates the data transmission process.

FIG. 12is a diagram for describing a selective communication method between a tag and a reader using a filter in the reader according to an embodiment of the present disclosure.

In step S301, the reader200receives tag information to collect data from the server300.

In step S302, the reader200determines a length of a filter, a random-number to be used for a filter generation and the number of hash functions.

In step S303, the reader200generates a filter based on the tag information to collect.

In step S304, the reader200transmits the filter information used for generating the filter including the random-number to be used for the filter generation, the length of the filter and the number of hash functions and the filter.

In step S305, the reader200determines a frame length.

In step S306, the reader200transmits a query message informing the frame length.

In step S307, the reader200starts a frame.

In step S308, the reader200checks whether data is received from the tag100.

In step S309, when data is not received from the tag100, the reader200waits for a start of next slot.

In step S310, when data is received from the tag100, the reader200transmits ACK message.

In step S311, the reader200checks whether the frame is ended.

In step S312, when the frame is not ended, the reader200performs step S309, and when the frame is ended, the reader200checks whether the number of slots in which collision occurs is 0.

In step S313, when the number of slots in which collision occurs is not 0, the reader200estimates the number of remaining tags with the number of slots in which collision occurs.

In step S314, the reader200determines a next frame length after step S313.

In step S315, the reader200transmits the collected data to the server300.

FIG. 13is a diagram for describing a selective communication method between a tag and a reader using a filter in the tag according to an embodiment of the present disclosure.

In step S401, the tag100receives filter information used for a filter generation including a random-number used for the filter generation, a length of a filter and the number of hash functions.

In step S402, the tag100transforms a tag unique ID to an index value.

In step S403, the tag100checks whether an index position value of the filter is 1.

In step S404, when the index position value of the filter is not 1, operates in a sleep mode.

In step S405, when the index position value of the filter is 1, the tag100receives a query message.

In step S406, the tag100selects a transport slot randomly in the frame length.

In step S407, the tag100checks whether the slot is its own selected slot.

In step S408, when the slot is not its own selected slot, the tag100waits until a start of next slot.

In step S409, when the slot is its own selected slot, the tag100transmits data to the reader200.

In step S410, the tag100checks whether ACK message is received.

In step S411, when the ACK message is not received, the tag100waits for a start of next frame and performs step S405.

In step S412, when the ACK message is received, the tag100operates in a sleep mode.

FIG. 14is a configuration diagram for describing a configuration of a tag performing a selective communication method between a tag and a reader according to an embodiment of the present disclosure.

As shown inFIG. 14, the tag100according to an embodiment of the present disclosure includes a communication module110, a memory120, a processor130and a sensing module140. However, not all constituent elements shown in the drawing are essential elements. The tag100may be implemented by more constituent elements than the constituent elements shown in the drawing, or the tag100may be implemented by less constituent elements than the constituent elements shown in the drawing.

Hereinafter, the detailed configuration and operation of each elements of the tag100ofFIG. 14are described.

The sensing module140is provided with various types of sensors and senses data through the provided sensors.

The communication module110communicates with the reader200.

The memory120stores at least one command.

The processor130is connected to the communication module110, the memory120and the sensing module140. By executing at least one command, the processor130receives a filter from the reader200through the communication module110, checks whether to pass through the filter based on the received filter and its own tag ID, and when passing through the filter, transmits data to the reader200.

According to various embodiments, when failing to pass the received filter, the processor130may operate in a sleep mode.

According to various embodiments, the processor130may transform its own tag ID to an index value and check whether to pass through the filter according to a position value corresponding to the transformed index value.

According to various embodiments, the processor130may transform its own tag ID to an index value and check whether to pass through the filter according to at least one position value corresponding to the transformed at least one index value.

According to various embodiments, the processor130may select a transport slot randomly within a frame length and transmit data to the selected transport slot through the communication module110.

FIG. 15is a configuration diagram for describing a configuration of a reader performing a selective communication method between a tag and a reader according to an embodiment of the present disclosure.

As shown inFIG. 15, the reader200according to an embodiment of the present disclosure includes a communication module210, a memory220and a processor230. However, not all constituent elements shown in the drawing are essential elements. The reader200may be implemented by more constituent elements than the constituent elements shown in the drawing, or the reader200may be implemented by less constituent elements than the constituent elements shown in the drawing.

Hereinafter, the detailed configuration and operation of each elements of the reader200ofFIG. 15are described.

The communication module210communicates with the tag100.

The memory220stores at least one command.

The processor230is connected to the communication module210and the memory220. By executing at least one command, the processor230generates a filter based on tag information of a tag to collect data, transmits the generated filter to the tag through the communication module210and receives data from a tag that selected through a filtering operation of the transmitted filter.

According to various embodiments, the processor230may generate the filter using at least one hash function.

According to various embodiments, the processor230may determine filter generation information required for generating the filter based on tag information to collect and generate the filter using the tag information and the determined filter generation information.

According to various embodiments, the processor230may determine the filter generation information including a filter length, a random-number generation seed and the number of hash functions.

According to various embodiments, the processor230may estimate the number of remaining tags that do not transmit data based on the number of slots in which collision occurs.

The method according to the embodiments of the present disclosure described above may be implemented with codes readable by a computer in a computer-readable recording medium. The method according to the embodiments of the present disclosure may be implemented with a computer program command form which can be executed through various computing means and stored in a computer-readable recording medium.

A computer-readable recording medium in which commands executable by a processor may be provided. When the commands are executed by the processor, the processor is configured to generate a filter based on tag information of a tag to collect data, transmit the generated filter to the tag through the communication module and receive data from a tag that selected through a filtering operation of the transmitted filter.

A computer-readable recording medium in which commands executable by a processor may be provided. When the commands are executed by the processor, the processor is configured to receive a filter from the reader through the communication module, check whether to pass through the filter based on the received filter and its own tag ID, and when passing through the filter, transmits the sensed data to the reader.

The computer-readable recording medium includes all kinds of recording media storing data which can be interpreted by a computer system. For example, the computer-readable recording medium may include a Read Only Memory (ROM), a Random-Access Memory (RAM), a magnetic tape, a magnetic disk, a flash memory, an optical data storage device, and the like. In addition, the computer-readable recording medium may be distributed in computer systems connected to a computer network and may be stored and executed as a code readable in a distribution manner.

In particular, the described features may be implemented within digital electronic circuitry, or computer hardware, firmware, or combinations thereof. The features may be implemented in a computer program product embodied in a storage device in a machine-readable storage device, for example, for execution by a programmable processor. Also, the features may be performed by a programmable processor executing a program of instructions for performing functions of the described embodiments, by operating on input data and generating an output. The described features may be implemented in at least one computer programs that can be executed on a programmable system including at least one programmable processor, at least one input device, and at least one output device which are combined to receive data and directives from a data storage system and to transmit data and directives to the data storage system. A computer program includes a set of directives that can be used directly or indirectly within a computer to perform a particular operation on a certain result. A computer program may be written in any form of programming language including compiled or interpreted languages and may be used in any form included as modules, elements, subroutines, or other units suitable for use in other computer environments or independently operable programs.

Suitable processors for execution of the program of directives include, for example, both general-purpose and special-purpose microprocessors, and a single processor or one of multiple processors of other type of computer. In addition, storage devices suitable for implementing the computer program directives and data implementing the described features include, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices, magnetic devices such as internal hard disks and removable disks, magneto-optical disks, and all forms of nonvolatile memories including CD-ROM and DVD-ROM disks. The processor and memory may be integrated within Application-Specific Integrated Circuits (ASICs) or added by ASICs.

While the present disclosure has been described on the basis of a series of functional blocks, it is not limited by the embodiments described above and the accompanying drawings and it will be apparent to those skilled in the art that various substitutions, modifications and variations can be made without departing from the scope of the present disclosure.

The combination of the above-described embodiments is not limited to the above-described embodiments, and various forms of combination in addition to the above-described embodiments may be provided according to implementation and/or necessity.

In the above-described embodiments, the methods are described on the basis of a flowchart as a series of operations or blocks, but the present disclosure is not limited to the order of the operations, and some operations may occur in different orders or at the same time unlike those described above. It will also be understood by those skilled in the art that the operations shown in the flowchart are not exclusive, and other operations may be included, or one or more operations in the flowchart may be omitted without affecting the scope of the present disclosure.

The above-described embodiments include examples of various aspects. While it is not possible to describe every possible combination for expressing various aspects, one of ordinary skill in the art will recognize that other combinations are possible. Accordingly, it is intended that the present disclosure include all alternatives, modifications and variations that fall within the scope of the following claims.