JP6682667B2 - Time slot communication system - Google Patents

Description

  The present invention relates to a communication system with a wireless tag.

  The system mentioned at the beginning is known, for example, from DE4439074A1. According to this document, at the time of transmission of the preamble, all radio tags must be active in order to allow simultaneous data transmission to the radio tags in the classified period. This procedure is energy or system inefficient. Further, in WO2010 / 004349A1, there is known a system in which wireless tags of individual time slots are classified. This causes the preamble to be emitted for synchronization with the communication station. In this preamble, more data packets are included, which indicates the error with respect to the reference time due to the synchronization status between the communication station and the wireless tag. The wireless tag goes from the sleep state to the active state at a time within the appearance of the preamble defined by the internal time base, where it receives one of the data packets. In order to adjust the next wake-up time anew and thus keep it in sync with the communication station, the RFID tag uses the data packet received each time and the error of the reference time encoded in it. , The internal time base is corrected. However, the next preamble for use proved to be disadvantageous, as it causes a relatively high amount of data.

DE4439074A1 WO2010 / 004349A1

  The present invention addresses the task of providing a system in which the problems initially discussed are avoided.

  This task is solved by the system according to claim 1.

  It is therefore an object of the invention to be a system, in which a plurality of time slots per time slot cycle are provided for communication in a repeating sequence, each time slot being assigned a unique time slot symbol. A system including a communication station for communicating with a plurality of RFID tags using a slot communication method, wherein the communication station emits a synchronized data signal including the time slot symbol for a current time slot. The wireless tag switches from the sleep state to the active state at the wake-up time, receives the synchronization data signal in the active state, and the received time slot symbol indicates the time slot specified in the wireless tag. To display the current time slot cycle Im slot cycle, is configured to define a new wake-up time corresponding to the next occurrence of the time slot that is specified, a system.

  The measures according to the invention also have the advantage that the synchronization between the communication station and the radio tag is as simple as possible and nevertheless recognized, maintained and guaranteed during the operation of the system. . Unlike the known procedure, here it is no longer necessary that all RFID tags be active at the same time in order to remain synchronized with the time scanning of the time slot communication method defined by the communication station. Absent. Similarly, with regard to the processing of this data, and also with regard to the total amount of data when communicating with the communication station, it has been found that the reception and evaluation of data, which is very costly and informs of a temporal error from the reference time, can be omitted. It was According to the present invention, it is sufficient for each RFID tag participating in communication with the communication station to notify via the time slot symbol indicating the time slot designated for the notification. Therefore, each of the RFID tags individually responds to the occurrence of the time slot symbol important to the notification, confirms the time slot symbol important to the notification, and uses it for the next wake-up time. It is defined by the timing of the time slot communication method set by the communication station. Thereby, the timeslot symbol is completely sufficient to uniquely identify each timeslot, for example using an individual timeslot identification signal for each timeslot. No additional information is required to synchronize the radio tag with the communication station, coded in the synchronization data signal as well as described with respect to known procedures. The wireless tag, by itself, is identified by the identification status of the time slot symbol, which appears at the time expected by the wireless tag or at the expected time period and indicates the time slot designated for the wireless tag, as a communication station by itself. Check the synchronization status of.

  After the wireless tag confirms its synchronization state as described above, when the wireless tag switches to the sleep state again, the next wake-up time is automatically known to the wireless tag. Is basically sufficient, since it is known for time scanning of. Therefore, the definition of a new wake-up time is defined by the fact that one of the RFID tags, for example a time-manipulated stage (for example a timer), is newly started with a timing parameter that was previously used to switch from the sleep state to the active state. Limited. After that, the RFID tag switches to sleep state again, where it operates by time operation, and again wakes up and switches from sleep state to active state until it is executed at the new wakeup time in the next time slot cycle. . However, the radio tag does not have to be forced to remain in sleep for the rest of the timeslots assigned to it, and can also handle additional tasks in the active state during timeslots or timeslot cycles. . Also, the time manipulation described so far operates in the background independently of other activities. The definition of a new wake-up time is realized by specifying an absolute or relative time task, eg relative to the time of the appearance of the synchronized data signal, or after an active state, sleep further until that time. It is relative to the time at which the state is taken or relative to the time at which the edges of the synchronized data signal occur until that time. However, a new definition of wake-up time is defined as the time period during which the time slot symbol is received, followed by the sleep state, or the sum of the sleep and active state periods, or various such states. The column totals can also be interpreted to specify a new wake-up time. Since each RFID tag operates its own time operating stage, and exemplary variations in the movement of each electronic component are not excluded, a new wake-up time definition exists for each RFID tag at that time. It can also include bass drift. To this end, for example, in a radio tag, the time difference between the expected and the actual appearance of a synchronized data signal having a time slot symbol indicating a time slot designated for each radio tag is measured, The timing of appearance is evaluated by the time manipulation stage for correction. However, compensation is used only in the confirmed sync state. However, if another time slot symbol is received at the expected time slot symbol position, there is no synchronization condition and the RFID tag must perform a new synchronization which is subsequently taken up.

  In the time slot communication method, m time slots, for example, 255 time slots are used within n seconds, for example, 15 seconds. Therefore, in this time slot communication method, m time slots within one time slot cycle are used for one communication by using the RFID tag. Each of the wireless tags can be classified into one of the time slots, where more wireless tags can also be classified into the designated time slot.

  Basically, one wireless tag has one wireless communication stage, also called a transceiver, and a logical stage associated therewith. The logic stages may be implemented, for example, entirely in hardware, or may be implemented by a microprocessor and a storage element or a microcontroller with integrated storage elements, which storage element Now the stored software is operational. A tag can use its wireless communication stage to receive a wireless signal, process the received data contained in this wireless signal with a logical stage, and possibly a logical stage to generate reply data, It is also emitted again as a radio signal via the radio communication stage. The wireless communication stage has means for wireless communication and means for converting analog signals into digital signals and vice versa.

  Such an RFID tag may have an energy storage element, for example a battery or a solar panel combined with a rechargeable battery, for supplying the energy. In order to operate with maximum energy efficiency, the wireless tag has several operating conditions. One wireless tag has a relatively high energy consumption when active. The active state exists when transmitting / receiving data, updating the display, measuring the battery voltage, and the like. On the other hand, in the sleep state, energy consumption is relatively low. Preferably, as many electronic components as possible are operated in a mode with the current supply switched off or dimmed or at least with the least possible energy requirement. The active state mainly has a time slot designated for the wireless tag for communication with the communication station. In the active state, the wireless tag has, for example, a readiness to receive commands and possibly received data from a communication station, and for processing with logical stages. In the active state, logic stages can also be used to generate transmit data and communicate with communication stations. Outside the time slot designated for the wireless tag, the wireless tag is primarily operated in an energy-saving sleep state. In the sleep state, the logic stage or the time-manipulation stage performs only the activity necessary for the timing for wake-up at the right time, so that the wireless tag can receive the synchronized data signal and / or Or, the next time slot designated for that RFID tag is ready for communication with the communication station. In order to operate with high energy efficiency and thereby achieve the longest lifetime of the wireless tag, keep the synchronized wireless tag in sleep state as long as possible and data with communication station in the shortest active period. There is a basic driving strategy of driving only when absolutely necessary for transmission.

  The communication station can be an autonomous device with a server function. Preferably, the communication station couples a disconnection site between a cable-connected communication with, for example, an information processing device (for example, a server) and a cableless wireless-based communication using a wireless tag.

  In order to freely use the communication with the communication station, the RFID tag is first registered or classified by the communication station.

  Furthermore, particularly preferred forms and further configurations of the invention are apparent from the dependent claims and the following description.

  Using the procedure according to the present invention, not only can the synchronization state between the communication station and the wireless tag be assured in a simple manner, but the wireless tag in the asynchronous state can be used again in the time slot communication method without any problem. It can be brought back in time and therefore resynchronized. To this end, such an asynchronous RFID tag does not switch periodically, as it would in the actual situation when it is in sync, for example from its sleep state to its active state once at any time. Switch and stay active in preparation for reception. If nothing is received during a specified period such as a time slot period, the device stays in the sleep state again and repeats the reception attempts until another time. Take advantage of the time slot symbols as soon as the synchronized data signal is received. Thereby, the received timeslot symbol most likely represents an unspecified timeslot, which is autonomously confirmed by the RFID tag. The RFID tag knows the system of appearance of the time slot symbols, and according to the evaluation of the received time slot symbol, the existing time slot cycle (first time) or the next time slot cycle may be performed. For the first time (second time), it voluntarily determines whether or not a designated time slot can be expected. In the first case, the wireless tag is configured to define one in the currently existing timeslot cycle, up to the next occurrence of the corresponding new wakeup time timeslot specified for it. The wireless tag confirms that the time slot specified will still appear in the currently existing timeslot cycle by evaluating the received timeslot symbol and by knowledge of the system of occurrence of timeslot symbol. . In the second case, the RFID tag defines one in the timeslot cycle following the currently existing timeslot cycle, up to the next occurrence of the corresponding new wakeup time timeslot specified for it. Composed. The RFID tag has already specified a time slot because it has already appeared in the past in this time slot cycle due to the evaluation of the received time slot symbol and the knowledge of the system of appearance of the time slot symbol. Make sure it will no longer appear in the timeslot cycle. As mentioned in the introduction to the synchronization state, the technique of this new wake-up time definition also uses the above-mentioned time operation, where the time operation is driven with a timing parameter, and with that parameter the synchronization state is entered. The desired start of is achieved. The timing parameters to be selected come from the RFID tag's inherent knowledge for the use of the next timeslot communication method, therefore the parameters are specified by the logic stage.

  The definition of the correct wake-up time for each wireless tag is made by the wireless tag based on its knowledge of the parameters of the time slot communication method. This parameter can be examined by or transmitted to the radio tag at its registration of the communication station, or it can already be programmed into the radio tag in advance. In both cases, the radio tag has a storage stage for the storage of the parameters of the timeslot communication method, and the radio tag has access to and evaluate this parameter for the definition of the new wake-up time. If configured, it serves your purpose. This parameter can present all the details of the timing of the timeslot communication method, for example, the parameters relating to the passage of time for the communication between the communication station and the wireless tag, a predefined time or time interval. Parameters related to the time slot, the parameters related to the basic structure of the time slot communication method, such as the total number of time slots, the time slot period, the time slot cycle period, or the confirmation for a single time slot. A parameter related to the timeslot symbol or an algorithm for the calculation of the timeslot symbol. Using this parameter, the asynchronous RFID tag can determine whether the specified timeslot can still be expected within the currently existing timeslot cycle, or the specified timeslot, based on the timeslot symbol just received. It can be easily and autonomously revealed automatically whether the slot is already known to be in the past and therefore the next designated time slot will appear in the next time slot cycle. The RFID tag concerned calculates a new wake-up time in the active state, switches to the sleep state, switches to the active state at the calculated wake-up time, receives the time slot symbol of the specified time slot, and then re-synchronizes. Become. In order to receive the synchronization data signal in the specified time slot, the radio tag will first become active again in the next time slot cycle, unless further activity is expected in the existing time slot. Switch to.

  According to a further aspect of the invention, the wireless tag has a storage stage for the storage of the presentation of the time slot symbol indicating the designated time slot.

  Both storage stages (storage stage for storage of parameters and storage stage for storage of presentations) can be realized by a single storage chip or by different storage chips. Both storage stages can be integrated in this storage chip on different storage areas and can be subject to different access rights. However, both storage stages can also be realized with different storage elements, based on safety engineering considerations.

  Obviously, it is advantageous to configure the presentation of the time slot symbols by means of the hardware address of the RFID tag, which uniquely identifies the RFID tag, and be programmed immutably in the second storage stage. This ensures that undesired false manipulations of the wireless tag are avoided. Since each RFID tag has one unique hardware address, it is possible to create a strict and non-interfering schematic classification for one time slot.

  Particularly preferably, the above-mentioned presentation of time slot symbols is realized by the least significant bit or least significant byte of the hardware address, where with this group of bits used, at least in the time slot cycle. The total number of time slots must be copyable. Thus, for example, for 256 time slots, only the least significant 8 bits or the least significant 1 byte of the hardware address, and for 128 time slots, only the least significant 7 bits are needed. Is. In this connection, it is advantageous if the total number of time slots corresponds to a power of two.

  The presentation of the timeslot symbol, or the timeslot symbol itself, can also consist of the above hardware address and other programmed numbers.

  The wireless tag is configured to check if the known time slot symbols present at the time of receiving the synchronized data signal match each other. The confirmation can be performed using, for example, an algorithm that supplies a confirmation result to the processor of the wireless tag when the software that describes the algorithm is activated. The algorithm can, for example, translate from received timeslot symbols into a presentation known to the wireless tag, and then a comparison can be made. However, the radio tag can also translate backwards from the presentation known to the radio tag to the expected time slot symbol, and then the received time slot symbol to the expected time slot symbol. It can also be compared with a slot symbol. However, since this is a very fast and relatively low energy requirement to the processor level with a simple enrollment comparison, it would be advantageous to simply make a comparison between two or binary coded symbols. .

  Basically, for each timeslot, a pre-defined and unambiguous confirmation for use can be made in the system. However, it is particularly configured that the communication station is configured to generate the time slot symbol as a consecutive number of each time slot (also referred to as a "slot ID") in response to the time slots appearing in order in the time slot cycle. preferable. Therefore, in each time slot cycle, number 1 is classified into the first time slot, number 2 is classified into the second time slot, and so on. By providing minimal data traffic in the transmission of data from the communication station to the wireless tag, too expensive algorithms can be avoided and time slot symbols can be generated in the simplest possible way. Only one data packet used for synchronization needs to be transmitted. Therefore, the total amount of data of the transmission of a timeslot symbol for use per timeslot or timeslot cycle is also largely unaffected. Therefore, the total number of data packets per time slot or time slot cycle required for synchronization is as small as possible, thus optimizing the channel registration. The total number of timeslots that occur in a timeslot cycle determines the total amount of bits needed to generate each number of timeslots, which makes the data packet needed for synchronization. Since each bit represents two states, it is advantageous if the total number of timeslots per timeslot cycle is a power of two. Therefore, the time period for receiving the time slot symbol can be shortened accordingly, which is advantageous for the energy balance of the wireless tag. Then, in particular, the part of the hardware address as the presentation of the time slot symbol known to the radio tag, if used at the radio tag side, matches the received time slot symbol with the stored time slot symbol. Confirmation can be done quickly and easily. The wireless tag synchronizes with the communication station or with the time scanning of the timeslot communication method defined thereby in the simplest way possible based on the number of timeslots.

  Basically, the synchronization data signal can be constructed exclusively via time slot symbols, for example address data for address processing of tags or commands for transmission of commands from the synchronization data signal. Further communication parameters required for communication between the communication station and the wireless tag, such as data, can be excluded. As explained above, since the time slot symbol is a very compact index for synchronization of communication in the system, it is conceivable to embed additional information in the synchronized data signal in addition to the time slot symbol, This will be discussed later.

  Therefore, according to a further aspect of the present invention, the communication station is configured to embed address data in the synchronized data signal, which is used to specify a plurality per time slot designated for said RFID tag. Of the wireless tags are individually addressed and the received time slot symbol signals its designated timeslot, the wireless tag evaluates the synchronized data signal with respect to the included address data, and It is configured to check whether the wireless tags are individually addressed.

  Similar to the use of the radio tag hardware address associated with the time slot symbol, the radio address hardware address that the communication station uniquely identifies to the radio tag, especially by omitting the least significant bit or least significant byte. It may also be advantageous to use one or more bits or bytes of to generate the address data. Therefore, existing systems utilize the hardware address of the RFID tag for unique addressing of each RFID tag. On the one hand, which time slot for an RFID tag is designated is defined by the least significant bit or least significant byte. Therefore, in order to keep this time slot in sync and to be individually addressable in this time slot, a relatively large number of radio tags are provided in a single time slot. Be classified correctly. Here, the additional bits or bytes of the individual hardware address of this wireless tag are used for the individual address processing of the special wireless tag. Moreover, the associated radio tag, which is just active to receive the time slot symbol, does not have to switch to sleep during that time, in order to see if the address data is present, in the existing time slot, This action represents a significant contribution to system efficiency as it has to be switched back into the active state at a later time. To be more precise, it becomes clear for all RFID tags which simultaneously wish to hear the synchronized data signal in this relatively short phase of the active state, whether the RFID tag is addressed or not.

  Similar to the address data embedding described, if the communication station is configured to embed the command data in the synchronized data signal, there is a further significant contribution to the system efficiency, by means of which the aforementioned radio can be used. A command can be sent by the wireless tag in the time slot specified for the tag, and the wireless tag synchronizes with the included command data when the received time slot symbol notifies the specified time slot. Configured to evaluate the digitized data signal and to execute the command. Thus, for example, a command can be sent to all RFID tags embedded in a specified time slot, which are executed by a relatively large group of RFID tags, without individually addressing them.

  Basically, the wireless tag can also already perform standardized (predefined) tasks by the identification of individual address processes without the need for receiving explicit commands. However, address data for addressing each wireless tag and command data for command transmission are transmitted by this individual wireless tag so that the wireless tag evaluates the command data and executes the command. It can be seen that it is particularly preferable if the wireless tags are constructed and addressed individually using the address data. Therefore, commands for individual RFID tags are sometimes transmitted in a relatively large group of RFID tags.

  According to a further aspect of the system, the wireless tag executes the command as a single time slot command and terminates the command executed within the only time slot in which the command was received. It is advantageously configured. This enables a quick and compact handling of requests such as those offered to the RFID tag via the communication station. Such a single timeslot command can be, for example, a so-called "PING" command, with which it is determined whether a specified timeslot exists, or, for example, from one saved page or site, to another. It is only checked if there are internal processing commands, such as switch commands for saving pages or switching to the site, that cause as little data traffic to the outside as possible. The storage page is a logical area (one address area) in which data for one image or the like is arranged or stored in the storage element. In some cases, a single time slot command is used to perform internal processing of data instead of transmitting data for processing by the wireless tag (for example, data to be displayed on the display) to the wireless tag. Only a command or a command instructing the wireless tag to transmit information to the communication station is transmitted.

  In this regard, at the end of the executed command, the RFID tag may be configured to generate confirmation data and to send confirmation data in each time slot in which the command is received. It is advantageous. Therefore, further, the data traffic caused by the confirmation remains limited to each time slot in which the command is transmitted. The next time slot remains unloaded according to the data, which favors system capacity.

  Further, the wireless tag can be configured to send confirmation data for a first portion of the timeslot (eg, the first one-half or the first one-third), This first part does not touch the second part of the subsequent time slot, which is located next in time in the synchronized data signal and before the appearance of the synchronized data signal in the next time slot. This structural or temporal division of the time slot results in that the confirmation data often requires only a short transmission, and therefore the remaining part of the relevant time slot, ie the second, for further data passage. Consider the situation where a portion (e.g. the second of a half or the second and third of a third) is used undisturbed.

  It should be noted that the duration of each part of a timeslot does not have to be defined by an invariantly set number and can be derived in a dynamic way from the respective configuration or use of a timeslot. Are generally described in.

  In a system, for example, there are 256 time slots in a time slot cycle of 15 seconds, 58.6 milliseconds each, and 2 to 5 problem-free RFID tags per time slot can be individually addressed. , Individual tasks in a single timeslot command can be delegated to it. If it is expected to impose a request on several RFID tags per time slot and therefore to communicate the above-mentioned confirmation data to all RFID tags in the existing time slots, each RFID tag will be It is advantageous to follow one arrangement principle. To this end, wireless tags have also been identified to address some wireless tags with address data, in addition to their own address, to evaluate those of other addressed wireless tags as well. It is configured to send the internal confirmation data for a period designated for the transmission of confirmation data at a time corresponding to the order of the group of addressed RFID tags as determined by the address. Since the communication station as the requester of the task knows the RFID tag to be addressed, only a minimum of data traffic is required to send the confirmation data, which is necessary for the communication station including the sequencing principle. , In which order and thus also up to what time or during which time period, which of the confirmation data contained is to be transmitted exactly.

  The wireless tag also uses a multi-time slot command over several time slots in order to transmit a larger amount of data between the communication station and the wireless tag, such that the amount of data transmission is short of time slots. Is configured to execute the command as. The processing of such commands may occur in adjacent time slots side by side or indirectly in adjacent time slots. Therefore, for example, the component of the command can be the total number of used time slots, confirmation of the used time slots, or a time slot group. The timeslots used can be limited in timeslot cycles, but can also be located jumping between several timeslot cycles. Such multi-time slot commands relate from the perspective of the RFID tag to, for example, downloading a larger amount of data from a communication station or uploading such a amount of data to a communication station. Similar to the single time slot command, the multi time slot command does not transmit the data for processing by the wireless tag (for example, the data for displaying on the display) to the wireless tag, but in some cases, transmits the data. , Only the command instructing the internal processing of the data and / or the command instructing the wireless tag to receive or transmit the data at a later time. After receiving the multi-time slot command, the wireless tag can autonomously time and switch to the energy saving sleep state again to switch to the active state at the time when the data transmission takes place. Here, in the frame of data transmission, new command communication, in particular, new address processing of the wireless tag is not necessary, because the communication station has already sent the data to the wireless tag by transmitting the multi-time slot command. This is because the transmission system has been defined. Therefore, for example, in a wireless tag having a display, the time of address processing of the wireless tag for receiving the data to be notified is completely temporally separated from the actual transmission time of the data to be notified. The transmission of the data to be notified can start at that time in the current or other time slot. The transmission of data to be notified can be extended over different timeslots of a timeslot cycle, and can be extended over several timeslot cycles.

  If the multi-time slot command corresponds to the data transmission from the communication station to the RFID tag, it is advantageous if the communication station is arranged to transmit the entire data distributed in several time slots, Here, one or several data packets are transmitted as a part of the whole data per time slot, and from each time slot, a second time slot portion adjacent to the first portion of the time slot is transmitted. Used for. In some cases, similar to the description for the single timeslot command, the second portion of the timeslot (eg, 2 minutes) may be used to avoid touching the other or first portion of the timeslot for other activities. 2 out of 1) is used. The same holds true, mutatis mutandis, for data transmission from the RFID tag to the communication station.

  Each time slot in which the multi-time slot command is executed by the wireless tag to notify the communication partner that the partial task is processed in each time slot in the time slot series required for processing the multi-time slot command. It is advantageous if it is configured to generate and send partial confirmation data at.

  In a particularly preferred configuration of the system, the radio tag is arranged to transmit partial confirmation data in the above-mentioned second part following the received data packet and before the end of each time slot. . Therefore, the entire data traffic generated by the multi-time slot command is integrated in the second part of the time slot.

  Corresponding to the configuration of the RFID tag included in the system, the communication station is further configured to receive and process the confirmation data in the reception period designated for it. Therefore, in the time period corresponding to the first part of each time slot, the confirmation data for the single time slot command is received, and for the time period corresponding to the second part of each time slot, for the multi time slot command. Confirmation data is received.

  In a preferred form of the present system, the command processing method described above is combined, so that the communication station is able to process the multi-time slot command performed by the first wireless tag for the designated time slot. The second wireless tag is addressed using the address data, and the single time slot command is transmitted to the second wireless tag using the command data. This makes it possible, in addition to transmitting a larger amount of data between the communication station and the first radio tag, to assign to the second radio tag an activity or task that causes a smaller amount of data to communicate with the communication device. To In this case, data communication with each RFID tag is handled in various parts of the respective time slots.

  According to a further aspect of the system, the communication station directs the radio tag to a time slot designated for the radio tag, and uses a command for an additional wake-up time that does not correspond to the normal designated time slot of the radio tag. The RFID tag can be used for data transmission with the communication station in a time slot different from the normal time slot of the RFID tag in the time slot communication method. ing. In addition to this, the wireless tag is configured to process this command and switch to the active state at the wake-up time forced by the communication station. This measure is important when communication with the designated RFID tag is being pushed to the communication station with (highest) priority. Then, the corresponding wireless tag normally synchronizes itself by using a time slot symbol indicating a time slot that is not designated in the wireless tag. After the processing of the task given to the unusual time slot, the applicable RFID tag adapts to the normal time slot of that RFID tag again, synchronizes itself, and then prepares for communication with the communication station in a synchronized state. Is made.

  In order to be able to independently search for the communication station, the RFID tag should be able to receive the synchronized data signal for a period of time cycle, in particular for a partly extended period of time. It is configured to check a plurality of times, and if the synchronized data signal does not come, switch the wireless channel and then execute the reception confirmation again. Since each communication station occupies a different radio channel, the result of the absence of a synchronized data signal for the tag to retrieve is the absence of a communication station for that radio channel or such communication. The station is out of range of the RFID tag, so other communication stations must search. This method can continue until a method of communication with a communication station is found and the wireless tag is registered with that station and is available in the system.

  The above-mentioned search can be simplified by limiting the search of the synchronized data signal by the wireless tag to a group of wireless channels set in advance, and that wireless channel is particularly useful when the wireless tag is connected to the communication station. It was previously transmitted by the station. This measure is reasonable for RFID tags that are newly integrated into the system, and for RFID tags that are already integrated that have been moved and disconnected in communication with the communication station as a result of the move. Especially rational. The limitation of the known radio channels is an energy-saving method, and furthermore, mainly to prevent the collision of radio channels taken by other machines, for example, a conventional WLAN (Wireless Local Area Network, draughtlosses locales Netzwerk). Be useful.

  A communication station shall have all available radio channels at the start of operation, in particular the radio channels previously programmed for the operation of that communication station, each radio channel being used by another communication station or its radio channel. Check for unused channels, and if there are such unused wireless channels, this wireless channel is configured to be used for communication with wireless tags assigned to or to be assigned to the communication station. This is an advantage for installing new communication stations in existing systems as easily and automatically as possible. The radio channel already shown can be seen by the fact that the synchronization data signals of other communication devices appear on that radio channel.

  The system of the present invention may include, for example, a plurality of communication stations located at various spatial locations, and each communication station is designated by selection of a wireless channel to which a group of RFID tags is assigned. it can. Therefore, it is possible to manage groups of RFID tags in the system in a simple and robust manner, and for each group of RFID tags, the same time slot communication method is used on different channels for each group.

In a preferred form of the system, the wireless tag has a display unit for displaying an image, the image is structured from image planes, each image plane is represented by image plane data, and the wireless tag is an image plane. and a discrete reception of data, which is configured to combine the image by superimposing the image plane, a communication station, configured to transmit the image plane data while communicating with the wireless tag by using the time slot Has been done. The advantage with this procedure is that only the image planes that undergo changes need to be selectively transmitted from the communication station to the RFID tag. Since the amount of data that has to be transmitted is relatively small compared to the amount of data that has to be transmitted for the entire image content, the above measures contribute significantly to system efficiency and energy efficiency. Moreover, the compression of the image data of each image plane that has to be transmitted can be optimized, thus minimizing the amount of data that has to be transmitted. This is possible because there are usually large "white" or "transparent" parts in the image plane that have to be transmitted, where very high compression rates are achieved. Therefore, this measure is kept low throughout the energy requirements or energy consumption of the RFID tag as low as possible, as the amount of data that has to be transmitted in order to perform image updates is reduced to a minimum. This has a very advantageous effect on the life of the wireless tag.

  In this situation, the wireless tag is configured to modify an existing image by receiving at least one new image plane of the image and replacing the existing image plane of the image with the image plane just received at that time. sell. In this case, the above command can be used. Thus, for example, the image data of the corresponding image plane is saved in a new memory page in the wireless tag, the image data of the image plane is downloaded from the communication station to the wireless tag using the multi-time slot command. Can be done. After the download is complete, you can use the image planes to combine the image with other image planes in a single time from the other memory pages previously used to create the image planes to the new memory page. It can be switched by a slot command.

  According to a preferred embodiment, the wireless tag is configured for the processing of images in which the image plane has the following meanings: first or second frequency of image content modification; first image content. Or second color; the first or second information category of image content. Therefore, an implementation suitable for each field of use of the system can be realized, and a combination of the meanings of the planes is also possible. Also, more than two image planes are possible, for example three, four or five image planes.

  According to such a preferred embodiment, the system realizes an electronic price display system, and the display unit of the RFID tag can be used for displaying product information or price information.

  In each case where a display unit is used, the display unit should also be realized, for example, also using LCD technology, preferably electronic ink technology (also called E-Ink synonymous with electronic paper). Is possible.

  According to a further aspect of the system, the wireless tag is configured to switch from the sleep state to the active state at a wake-up time having a lead time before the appearance of the synchronized data signal. This measure may not be evaluated significantly, and therefore significantly, that the entire RFID tag, in other words all the components of the RFID tag necessary for receiving and processing the synchronized data signal, is fully operational. Ensure that partial reception of high synchronization data signals is avoided.

  In this case, the lead time period can be selected to be the first small portion of the time slot period of the time slot. The lead time may be, for example, between 0.1% and 10% of the time slot period.

  According to a further aspect of the system, the wireless tag is configured to be in an active state during a reception period that is longer than a transmission period of the synchronized data signal. The advantage with this procedure is that it guarantees that the entire synchronized data signal can be received reliably. The reception period currently to be used can be set to be fixed in a synchronized state for each reception method. However, based on the drift of the time base of the RFID tag confirmed based on the appearance of the synchronized data signal, the period of the active state is dynamically adjusted to each drift including the above-mentioned lead time. It is also possible. The reception period can also be limited by detection of the loss of the synchronized data signal.

  In order to guarantee optimized reception conditions, the RFID tag in such a system maintains the active state entered for the reception of the synchronized data signal, including the tracking period after the reception of the synchronized data signal. It is also possible to be configured as follows. This follow-up period is defined, for example, in a predetermined period of the active state, or can be dynamically adjusted in some cases depending on the current drift or reception conditions.

  In this case, the follow-up period can be selected such that the follow-up period is the second small portion of the time slot period. The duration of the follow-up period may be, for example, between 0.1% and 10% of the time slot period. The duration of the follow-up period may match or differ from the lead-time period.

  It has proved to be particularly advantageous that the communication station is arranged to send a synchronized data signal at the beginning of each time slot. This measure allows the beginning of a time slot to be very accurately identified with respect to the RFID tag, and the correction of drift of the RFID tag's internal time base can no longer be done at the beginning of the time slot. Therefore, all further tasks of the RFID tag can proceed during each time slot with as good a synchronization as possible with the time base of the communication station, and the remaining total length of the time slot is above the further task. To ensure that it is ready for use.

The communication station is configured to embed confirmation period data in the synchronized data signal that is used to allow confirmation data for the RFID tag to be set during the expected confirmation time. It has been found that the wireless tag is arranged to send the confirmation data at a specified time, which is advantageous in terms of a systematic and flexible communication method between the communication station and the wireless tag. This is particularly advantageous when a plurality of RFID tags are addressed in one time slot and each RFID tag can be provided with an individual confirmation time. Then, each RFID tag can execute a command, for example, after receiving the synchronization data signal, switch to an energy-saving sleep state, and then switch to the active state again only after a confirmation time individually determined for the RFID tag. , Can send confirmation data of the wireless tag and then switch to sleep again as soon as possible. Therefore, the determination of the confirmation time made in the synchronized data signal is a measure for improving the energy efficiency of the wireless tag and a measure for avoiding a collision , and therefore has a lasting effect on the lifetime of the wireless tag. The checkpoint data may indicate an absolute time in the time slot by measuring the absolute time from the beginning of the time slot, or, for example, a dwell period of sleep with respect to a previous event, which previous event may be, for example, , The end of the synchronization data signal or the end of the active state, which can be confirmed in the case of the wireless tag.

  A further aspect of the present invention relates to the allocation of a plurality of wireless tags to a plurality of communication stations. In order to obtain as balanced a distribution of wireless tags and communication stations as possible, the data processing device, eg a server, is arranged to determine which wireless tags may be connected to which communication station. Has been found to be advantageous. The basis for this decision may be the existing distribution of connections in the system, which distribution has to be optimized in terms of the newly added RFID tag. However, there may be a fixed and set connection pattern, which is defined and realized in advance.

  To allow the system to be as dynamic as possible, the data processing device, eg, the server, is configured to terminate the existing connection with the communication station and cause the wireless tag to connect to another communication station. Can be advantageous. In this case, the server reacts to the unbalanced distribution of the RFID tags and positively influences the assignment of the RFID tags and the communication stations to change the assignment in order to realize optimized load balancing. can do.

  This and further aspects of the invention will be apparent from the drawings described below.

The invention will be explained in more detail below on the basis of an embodiment with reference to the accompanying drawings, without being limited to that embodiment. Here, the same members are denoted by the same reference numerals in each drawing. The drawings schematically show the following:
FIG. 1 shows the system of the invention; Figure 2 shows the distribution of radio channels in the system; FIG. 3 shows a block circuit diagram of the electronic price display board; FIG. 4 shows the assembly of the images; FIG. 5 shows a first state diagram; FIG. 6A shows a second state diagram; FIG. 6B shows a first data structure; FIG. 7A shows a second state diagram; FIG. 7B shows a second data structure; FIG. 8A shows a third state diagram; FIG. 8B shows a third data structure. FIG. 8C shows a fourth data structure.

  FIG. 1 shows an electronic price display system installed in a retail company building as a system 1 of the present invention for communication according to the time slot communication method. For clarity, the drawing omits the representation of the building and its furniture. The system 1 includes a server 2, first and second communication stations 3 and 4 (hereinafter abbreviated as station) and eight wireless tags 7-14 (hereinafter abbreviated as ESL for Electronic Shelf Label). Including. The server is located in the office and is connected to stations 3 and 4 via a wired communication circuit (LAN) L. Stations 3 and 4 are connected by radio signals to ESL 7-13. Stations 3 and 4 are attached to various points of the ceiling in the room of sale. The ESL 7-14 is attached to the shelf corresponding to the product whose price and product information is displayed using the ESL 7-14. The product information is transmitted from the server 2 to the stations 3 and 4, and individually transmitted from the stations 3 and 4 to each ESL 7-14.

  Each station 3, 4 respectively covers one radio area, the first radio area boundary of the station 3 and the second radio area boundary 6 of the station 4 being shown schematically in part in FIG. In this wireless area, there is an overlapping area where ESLs 9-11 are arranged.

  At the start of system operation, stations 3 and 4 were started up one after another. Each station 3 or 4 knows the radio channel with the channel numbers 3, 5, 8, 9, 10 which is prioritized for the operation of the system 1. This is shown in FIG. 2 where the various frequency bands 15-22 are represented by channel number K. Frequency bands 15, 16, and 17 can be used to operate a conventional WLAN. The frequency bands 18, 19, 20-22 prioritized for the operation of the system 1 correspond to the channel numbers 3, 5, 8-10 and do not overlap with the WLAN frequency band 15-17. Station 3 automatically selected its radio channel 3 because the radio channel with channel number 3 was first checked for already being used by another station. When confirming the vacant radio channel, it is confirmed that the radio channel having the channel number 3 is already in use, and the next vacant radio channel having the channel number 5 is identified. The radio channel with number 5 was automatically selected. However, the wireless channel allocation can be fixed.

  The ESL 7-14 confirms that the radio signal of the corresponding station 3 or 4 is present in one or more radio channels as soon as the station 3 or 4 is put in the respective radio area. ESLs 7 and 8 connect to the first station 3. The ESLs 12-14 connect to the second station 4. For ESLs 9-11, it is confirmed to them that each station 3 and 4 is available. At that time, each ESL 9-11 confirms the reception quality of the radio signal received by the respective stations 3 and 4, and then determines the station 3 or 4 that has confirmed the best reception quality. This is to establish a connection with the station 3 or 4 which has confirmed the best reception quality in each radio channel (channel number 3 or 5). However, this decision-making process may take place in stations 3 and 4, in which case stations 3 and 4 check each reception quality of the communication with ESL 9-11 and communicate with each ESL 9-11. Communicate with each other as to which of stations 3 and 4 connects to which of ESLs 9-11 as the situation is more favorable. However, since the server 2 is connected to the stations 3 and 4, the decision making regarding the allocation between the ESL 9-11 and the stations 3 and 4 can be transferred to the server 2. Therefore, a wireless channel is first selected (also referred to as “channel scan”) within the frame for establishing a connection between the respective ESLs 7-14, and in some cases, after the reception quality in each wireless channel is evaluated, The unique hardware address of the ESL 7-14 is transmitted to the stations 3, 4 selected for communication. As a result, the ESLs 7-14 assigned to the respective stations 3 and 4 can be known. This first assignment between stations 3, 4 and ESL 7-14 is transmitted to server 2.

  Next, a second allocation between each ESL 7-14 and exactly one item is made. As a result, the server knows the location of the merchandise indicated using shelving, so which shelf and where on the shelf each ESL 7-14 is (or should be) in the room of sale. ) Know.

  FIG. 3 shows a block circuit diagram of ESL7 as an alternative to ESL7-14, which are all identically configured in the system. The ESL 7 is realized by a wireless module 24, a processor 25 for data processing, control of operating conditions and preparation of functions, a memory 26 for storing data and programs, and electronic ink technology for power saving. And a display unit 27 for displaying. The wireless module 24 is used for communication based on wireless communication with the station 3 or 4, and in the communication, received data is generated from a received wireless signal and transmitted to the processor 25 or transmitted to the processor 25. The transmitted data thus converted is converted into a wireless signal. The data stored in memory 26 can be assigned to either processor 25 or display 27. Further, it is a matter of what memory type (ROM, EEPROM, RAM, etc.) memory 26 is, or how memory 26 is logically or physically assigned to processor 25 and / or display 27. No distinction is made in the attached drawings. In the selected drawings, the representation of connections such as signal lines or data lines between function blocks 24-27 and the representation of the energy store (battery in the case of the invention) have been omitted.

  The image data BD for generating an image using the display unit 27, the hardware address data HAD for designating the hardware address of the ESL, and the parameter data PD regarding the parameter setting of the time slot communication method are stored in the memory 26. The image data BD specifies the first image plane of the image by the first plane data ED2 and the second image plane of the image by the second plane data ED2. It has to be mentioned here that additional image planes can also exist.

  The hardware address data HAD includes four bytes B3, B2, B1 and B0, and B0 is the least significant byte of the hardware address data.

  Using the processor 25, different plane data ED1 and ED2 are assembled into an entire image in ESL7. The first and second plane data ED1 and ED2 correspond to one image information of each pixel. However, "transparent", "background", or "background color" is defined as image information specific to both image planes. As a result, the individual image planes are overlaid pixel by pixel, and thus the entire image can be created by superimposing the image content at the same coordinates of the pixels in each image plane. The image is in bitmap format, but may be in other formats, such as JPG.

  This image formation is shown schematically in FIG. The first image plane 28 represented through the first plane data ED1 basically contains static image information 29 about a product, and this static image information is changed only when the ESL 7 is assigned to another product. To be done. The static image information 29 relates to, for example, a descriptive sentence related to a product. All other image parts are defined as "transparent". The second image plane 30 represented through the second plane data ED2 is basically relatively frequent compared to static image information, eg dynamic image information 31 that changes daily, several times daily, or weekly. including. The dynamic image information 31 relates, for example, to the price of the product or the validity of the discount, for example the start and end dates or times or other conditions attached to the discount. All other image parts are defined as "transparent". The entire image 32 represented through the image data BD formed by superimposing each pixel of the first image plane 28 with the pixel of the second image plane 30 which corresponds completely to that pixel is a static and dynamic image. The information 29, 32 and the portion marked with "transparent" between them are shown.

  The ESL 7 can receive all the field image data BD in a compressed form, decompress it, and place it in the memory 26. This may be done, for example, on the initial transmission of the entire image. However, this method takes a relatively long time and thus causes a relatively high energy requirement. As long as the image is in ESL7, partial updating of the image is more efficient as it can be performed with less energy. To that end, the ESL 7 receives each image plane (eg the second image plane 30) that has to be updated separately from the other image planes already placed in the memory 26 (eg the first image plane 28), It can be unzipped and placed in memory 26. Next, in order to newly form the entire image 32, the newly created second plane data ED2 is internally accessed (switched from one memory side to the other memory side).

  The ESL 7 includes a time control stage 33, which may be implemented as a separate hardware element or at least partially implemented using the processor 25. This time control stage 33 produces a time base typical of ESLs and uses this time base to control the state timing (transitions and terminations) of ESL 7. Timing control is performed, for example, using timing parameters known per se and / or provided to the processor.

  The time slot communication method used in the system 1 will be described below with reference to FIGS. Here, only the ESLs 7-9 assigned to the first stage 3 are taken up, but the same description applies to the ESLs 11-14 assigned to the second station 4. In the state diagrams shown in FIGS. 5-8, the time t is described on the abscissa. The ordinate describes the respective state Z for the elements of the system 2 considered in the description. Therefore, this figure shows the course of time.

  In each of FIGS. 5-8, the uppermost state progress shows the state of the stage 3 marked with ST. During one time slot cycle period DC (for example, 15 seconds), N time slots Z1.Z having the same time slot period DS (for example, about 58 milliseconds) Z1. . . ZN (eg 256) can be used. During the time slot cycle period DC, stage 3 is switched between the transmitting state T and the stationary state R. The transmission state T is always the time slot Z1. . . ZN, taken at the beginning of the ZN and using the respective synchronized data signal SD, the respective time slot symbol ZS1, ZS2 ,. . . It is held during the synchronized data signal period DSD (or the transmitted period DSD of the synchronized data signal SD) to transmit the ZSN. Each time slot symbol ZS1. . . As the ZSN, each time slot Z1. . . ZN consecutive numbers are timeslots Z1. . . It is used according to the order of appearance of ZN. Therefore, in hexadecimal (marked with "Hex"), the first time slot Z1 has the time slot symbol Hex 00, the second time slot Z2 has the time slot symbol Hex 01, etc. The slot symbol ZN (the 256th time slot Z256 in this example) is labeled with Hex FF.

  The following ESLs 7-9 are written in hexadecimal notation (most significant byte on the left = fourth byte B3: third byte B2: second byte B1: least significant byte on the left = first byte B0). Hardware address is taken up. The hardware address of ESL7-9 is unchanged during the actual operation of the system 1. However, in order to describe various aspects of system 1 using a visible number of ESLs, the drawings sometimes give different hardware addresses to the ESLs of system 1, or one or more ESLs are It may not be included in the description.

  In the case of FIG. 5, the hardware address of the first ESL 7 is Hex B 2: 00: 01: 00, that of the second ESL 8 is Hex B 2: 00: 01: 01, and that of the third ESL 9 is Hex B 2: 00: 02: 00. . The fourth ESL10 is not considered.

  In the case of FIG. 6, the hardware address of the first ESL 7 is Hex B 2: 00: 01: 00, that of the second ESL 8 is Hex B 2: 00: 02: 00, and that of the third ESL 9 is Hex B 2: 00: 03: 00. . The fourth ESL10 is not considered.

  In the case of FIG. 7, the hardware address of the first ESL7 is Hex B 2: 00: 01: 00. The remaining three ESLs 8-10 are not considered.

  In the case of FIG. 8, the hardware address of the first ESL7 is Hex B2: 00: 01: 00, that of the second ESL8 is Hex B2: 00: 01: 01, and that of the third ESL9 is Hex B2: 00: 02: 01. The one for 4ESL10 is. The fourth ESL10 is B2: 00: 03: 01.

  In the system 1, the least significant byte B0 is used to confirm the time slot assigned to each ESL 7-10 and appearing within the frame of the time slot communication method in each ESL 7-10. Except for the least significant byte B0, the remaining three bytes B1-B3 of the hardware address are the time slots Z1. . . Used to individually address ESLs 7-10 in ZN.

  In FIG. 5, the first ESL 7 is in a more synchronized state. The first ESL7 wakes up from the sleep state S at the first wake-up time TA1, switches to the ready state E for reception with the passage of the relatively short lead time DV, and before the appearance of the expected synchronized data signal SD, Receive the synchronization data signal SD during the reception period DE having one time slot symbol ZS1 (Hex 00) and compare the least significant byte B0 of its hardware address (Hex 00) with the received time slot symbol ZS1. Then, confirm that the first time slot Z1 assigned to the first ESL7 is displayed (matching bytes to be compared: hardware address B0 and first time slot symbol ZS1) to define the new wakeup time. As a parameter of the time control stage 33 used to control the wakeup , Save for wake-up in the next time slot cycle, enter sleep state S again with a relatively short lead time DN, and after the set sleep state dwell time expires, wake up as planned (second) At time TA2, it occurs after the lead time VD, before the new beginning of the first time strobe cycle Z1. The same applies analogously to ESL8, which is in a synchronized state like the first ESL7.

  The third ESL 9 is in an unsynchronized state before the synchronization time TSY, which is only conceptually indicated by a dashed arrow 34 parallel to the time axis. The third ESL 9 wakes up at an arbitrarily chosen first wake-up time TA1 and switches from sleep state S to active discharge E ready for reception, in which state it waits until it receives a new appearance of the synchronized data signal SD. , In which case the second time slot symbol ZS2 (Hex 01) is received. The third ESL9 has determined that, based on the least significant byte B (Hex 01) of its hardware address, the time slot assigned to it has already become a past thing during the current time slot cycle, and thus the time slot symbol Recognizing that the next time slot with Hex 00 will finally come in the next time slot cycle, then the time slot Z2 just seen will have one time slot beside its original time slot Z1. The separation is calculated, which is referred to below as the time slot difference. Therefore, in the third ESL 9, the time control stage 33, like the ESL in the synchronized state, has a new wake-up time TA2 before the appearance of the lead time DV before the appearance of the first time slot Z1 of the next time slot cycle. Are programmed to separate. The dwell period DSA that must wait while in the sleep state S is calculated as follows: the time slot period DS is subtracted from the sleep state dwell period (if in the synchronized state) to obtain the time slot. Multiply the difference (value 1 in this case). Therefore, the third ESL 9 is again in the synchronized state as the concept is shown by the continuous line, and after switching from the active state E to the sleep state S, after the end of the residence period DAS, the new wake-up time TA2 is reached. Is switched to the active state E again.

  Based on FIG. 6A, the individual addressing of the ESLs 7-9 and the individual pointing of the ESLs 7-9 with a single timeslot command is described. Only the first time slot Z1 embedded between the two synchronized data signals SD is shown. The station 3 embeds address data AD, command data CD, and confirmation time data ZD in the synchronized data signal SD of the first time slot Z1. The first ESL7 is based on the address data AD Hex B2: 00: 01, the second ESL8 is based on the address data AD Hex B2: 00: 02, and the third ESL9 is based on the address data Hex B2: 00: 03. To be done. Using the command data CD, a "PING" command is transmitted to the first ESL7, a "PING" command is transmitted to the second ESL, and a "SWPAG2" command is transmitted to the third ESL9. This command is a single time slot command that is processed in such ESLs 7-9, spending a small amount of time immediately after being decoded. The above two "PING" commands are used to test whether the addressed ESL7,8 responds with the confirmation data ACD, that is, whether the ESL7,8 is present or reacts and is synchronized in the first place. Using the "SWAPG2" command, for example, to change the image shown using the display unit 27 as described in connection with FIG. 4, the third ESL 9 is changed from the (first) current memory page to the second memory page. Can be switched to. Further, the confirmation time is transmitted by transmitting the first stationary period DR1 for the first ESL7, the second stationary period DR2 for the second ESL8, and the second stationary period DR2 for the third EL9 together with the synchronized data signal SD. The reference point of the three stationary periods DR1-DR3 is always the end of the reception period DE. The data structure transmitted using the synchronized data signal SD at the beginning of the first time slot Z1 is shown in FIG. 6B.

  Instead of a single rest period DR1-DR3, the maximum duration of the response that results from the sum of each rest period DR1-DR3 and the period for sending the confirmation data ACD may be mentioned.

  According to FIG. 6A, each ESL7-9 indicates a time slot to which the first time slot symbol Z1 is assigned (in all three ESL7-9, the least significant byte B0 of the hardware address is Hex 00). Yes, I realize I am in sync. Confirmation of the address data AD indicates that each ESL7-9 is individually addressed (there are the remaining three bytes B1-B3 of each hardware in the address data AD), and is designated to each ESL7-9. Command is executed immediately after being decoded, and the individual rest period DR1. . . After the end of DR3, the individual confirmation data ACD is transmitted with the station 3 ready to receive the confirmation data ACD during the station reception period SDE. The complete processing of the single time slot command, including the communication of the confirmation data ACD, is done during the first part 36 of the time slot Z1, which allows the second part 37 to perform other tasks such as multi-time. It can be used to process slot commands, which is taken up in detail in FIGS. 7-8.

  FIG. 7A shows the processing of a multi-time slot command in which the first ESL 7 has all the data (eg all of the images that have to be shown, over three adjacent time slots Z1-Z3). Or only one image plane of the image) into three data packets DAT1. . . The data is divided into DAT3 and received from the station 3. Using the synchronized data signal SD, the first ESL7 recognizes the synchronized state of the first ESL7 and that it is individually addressed (address data Hex B2: 00: 01), and during the time slot Z1-Z3. In the above three data packets DAT1. . . It receives and decodes the "DATA_INIT" command used to instruct the first ESL7 to receive DAT3, enters the sleep state S at the end of the receiving period DE for the first waiting period DW1, and the first waiting period DW1 is a time slot. It ends at the same time as the end of the first half of the period DS. At the beginning of the second part 37 of the first time slot Z1, the station 3 enters the transmission state T and the first ESL7 is ready for reception so as to receive the first data packet DAT1 during the data transmission period DT. The active state E is entered. After that, the first ESL 7 confirms the successful reception using the partial confirmation data ACD1 during the confirmation period DA in which the station 3 is also in the reception state E. The confirmation period DA ends before the end of the first time slot Z1. After the confirmation period DA has ended, the first ESL 7 remains in the sleep state S during the second waiting period DW2 which continues until the end of the first part 36 of the second (next) time slot Z2. At the beginning of the second part 37 of the second time slot Z2, the station 3 enters the transmission state T and the first ESL 7 is ready to receive the second data packet DAT2 during the data transmission period DT. The active state E is entered. The same applies to the third time slot Z3, the end of which is the end of the data transmission. Each successfully transmitted data packet DAT1-DAT3 is confirmed using the partial confirmation data ACD1-ACD3. The data structure transmitted at the beginning of the first time slot Z1 using the synchronized data signal SD is shown in FIG. 7B.

  Data transmission using a combination of one multi-time slot command and three single time slot commands is described with reference to FIG. 8A. The first ESL7 is synchronized with the first ESL7 (the least significant byte B0 of the hardware address is Hex 00) and individually addressed (address data Hex B2: 00) using the synchronized data signal SD. : 01) and recognizes three data packets DAT1. . . It receives and decodes the "DATA_INIT" command used to instruct the first ESL7 to receive DAT3. The data structure transmitted at the beginning of the first time slot Z1 using the synchronized data signal SD is shown in FIG. 8B. Data transmission from station 3 to the first ESL 7 continues as described for FIG. 7A.

  The second time slot symbol Z2 indicates the time slot designated for ESL8-10 (the least significant byte B0 of the hardware address is Hex 01 in all three ESL8-10), so the remaining three ESL8s. -10 recognizes that ESL8-10 is synchronized at the beginning of the second time slot. Confirmation of the address data AD, as described with respect to FIG. 6A, indicates that each ESL 8-10 is individually addressed (in the address data AD, there are the three remaining bytes B1-B3 of each hardware). ), The commands specified in each ESL 8-10 (three “PING” commands in this case) are decoded and then executed immediately, and the individual rest periods DR1. . . After the end of DR3, the individual confirmation data ACD is transmitted to the station 3. The data structure transmitted at the beginning of the second time slot Z2 using the synchronized data signal SD is shown in FIG. 8C.

  As can be seen clearly, the first part 36 of the second time slot Z2 for a single time slot command and the second part 37 of the second time slot Z2 for a multi time slot command are reserved for the respective required data communication. Therefore, the three single time slot commands and the one multi time slot command are handled almost simultaneously for the time unit "time slot" in the second time slot T2. However, the assignment of each command type to the timeslot portions 36, 37 can be reversed.

  Lastly, the drawings described in detail above are merely examples which can be modified in various ways by a person skilled in the art without departing from the scope of the invention. As noted for completeness, the use of the indefinite article "ein" or "eine" does not exclude that there may be more than one feature of interest.

Claims (4)

-A plurality of time slots (Z1-ZN) are provided for communication per one time slot cycle in a repeating sequence, and a unique time slot symbol (ZS1-ZSN) is attached to each time slot (Z1-ZN). A system (1) including a communication station (3, 4) for communicating with a plurality of wireless tags (7-14) using a time slot communication method as set forth,
The communication station is arranged to emit a synchronization data signal (SD) containing its time slot symbol (Z1-ZN) for the current time slot (Z1-ZN),
-The wireless tag (7-15) is
+ At wake-up time (TA1), switch from sleep state (S) to active state (E),
+ In the active state (E), receive the synchronization data signal (SD),
+ When the received time slot symbol (ZS1-ZSN) indicates the time slot (Z1-ZN) designated in the wireless tag (7-15), in the subsequent time slot cycle of the current time slot cycle, Configured to define a new wake-up time (TA2) corresponding to the next occurrence of the designated time slot (Z1-ZN) ,
-When completing the command being executed, the wireless tag (7-14) generates confirmation data (ACD) in the time slot (Z1-ZN) that received the command and transmits the confirmation data (ACD). Is configured as
-The wireless tag (7-14) is addressed to one or more other than its own address when a plurality of wireless tags (7-14) are addressed using the address data (AD). The wireless tags (7-14) that are being addressed and based on the confirmed address in the group of wireless tags (7-14) being addressed within the time period specified for the transmission of the confirmation data (ACD). It is configured to send your confirmation data (ACD) at the time corresponding to your order confirmed by
The wireless tag (7-14) comprises a display unit for the display of the image (32), the image (32) being structured into image planes (28, 30), each image plane (28, 30) being It is represented by the image plane data (ED1, ED2), and the wireless tag (7-14) individually receives the image plane data (ED1, ED2) and superimposes the image planes (28, 39) on the image. Configured to assemble (32),
-Communication stations (3, 4) are timeslots so that only the image planes (ED1, ED2) where the changes occur are selectively transmitted from the communication stations (3, 4) to the RFID tag (7-14). A system (1) configured to transmit each image plane data (ED1, ED2) while communicating with the wireless tag (7-14) using the . -The wireless tag (7-14) is
+ Receiving at least one new image plane (28, 30) of the image (32),
+ Replacing the existing image plane (28, 30) of the image (32) with the image plane (28, 30) just received to create a new look image,
The system (1) of claim 1, wherein the system (1) is configured to modify an existing image (32). The wireless tag (7-14) has the following meanings on the image plane (28, 30):
-The first or second frequency of image content changes, or
-The first or second color of the image content, or
-First or second information category of image content,
A system (1) according to claim 1 or 2, wherein the system (1) is configured to modify the image (32) provided.   The system (1) realizes an electronic price display system, and the display unit (27) of the wireless tag (7-14) is used as a display of product information or price information, etc. 4. The system (1) described in 1.

Images