Interference canceling for backscatter communications

Abstract

Various examples of the disclosure generally relate to a backscatter transmission. Some examples relate to a method for a receiver node (130) configured to receive information from a backscatter communication device (120). The backscatter communication device (120) is configured to transmit information by modulating electromagnetic carrier signals that are incident at the backscatter communication device (120). The method (700) comprises determining (708) an initiation for a silent period (424) of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device (120), and receiving (712) information from the backscatter communication device (120), based on the determined initiation. The determined initiation enables the receiver device (130) to estimate (710) interference of the electromagnetic carrier signals based on an analysis of the silent period (424), and to perform an interference cancelling (714) in the electromagnetic carrier signals based on the estimated interference.

Description

[0001] INTERFERENCE CANCELING FOR BACKSCATTER COMMUNICATIONS

[0002] TECHNICAL FIELD

[0003] Various examples of the disclosure generally pertain to backscatter communication. Various examples specifically pertain to interference estimation and interference canceling at a receiver node receiving backscatter communication.

[0004] BACKGROUND

[0005] Radio communication has traditionally relied on power-hungry components in both transmitters and receivers. The conventional approach requires devices to generate radio signals using analog components such as digital-to-analog converters (DACs), mixers, oscillators, and power amplifiers in the transmitter, along with low noise amplifiers, mixers, oscillators, and analog- to-digital converters (ADCs) in the receiver. This traditional method of communication is associated with high energy consumption, which is becoming increasingly problematic due to the growing demand for battery-powered devices and environmental concerns related to increased battery production.

[0006] Emerging technologies like 5G and the upcoming 6G networks have placed even greater emphasis on reducing power consumption while maintaining or increasing data transfer rates. However, these advancements still rely heavily on traditional radio communication principles and do not fundamentally address the energy efficiency challenges inherent in conventional methods.

[0007] Backscatter technology offers a promising alternative that can help reduce the energy consumption associated with traditional radio communication methods. With backscatter communication (BSC), ultra-low power devices can modulate and transmit their information through not reflecting and reflecting RF signals instead of generating actual radio waves, thus avoiding the use of power-hungry transmitters. This approach has significant environmental benefits by reducing the need for frequent battery replacements in low-power Internet-of-Things (loT) devices.

[0008] The focus of the present disclosure is specifically on bi-static dedicated backscatter communication, which involves a separate transmitter and receiver. This method has the advantage of allowing for more flexible deployment but also presents unique challenges compared to other forms of backscatter communication. Bi-static dedicated backscatter communication offers the potential for improved range and reliability in certain applications.

[0009] However, current methods in bi-static dedicated backscatter communication face significant technical hurdles. One major problem is the strong interference caused by the carrier wave signal at the receiver. This interference can be significantly stronger than the actual backscatter signal, making detection and demodulation extremely challenging. Additionally, in a bi-static scenario where the transmitter and receiver are separate devices, the receiver may not have knowledge of the carrier wave signal, further complicating the situation.

[0010] Current methods struggle to overcome these challenges due to limitations in signal processing capabilities. Interference cancellation techniques may rely on having prior knowledge of the interfering signal or require complex adaptive algorithms that consume power and computational resources. SUMMARY

[0011] Accordingly, a need exists for advanced techniques for estimation and cancellation of interference in backscatter communication, in particular in bi-static dedicated backscatter communication, thereby overcoming the above mentioned disadvantages of the prior art at least in part.

[0012] This need is met by the features of the independent claims. The features of the dependent claims define embodiments.

[0013] One aspect of the present disclosure relates to a method for a receiver node configured to receive information from a backscatter communication device.

[0014] The receiver node determines an initiation for a silent period of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device. This determination enables the receiver device to estimate interference of the electromagnetic carrier signals based on an analysis of the silent period, and to perform an interference cancelling in the electromagnetic carrier signals based on the estimated interference.

[0015] A receiver node may be understood as a device that receives information from a backscatter communication device by detecting changes in the electromagnetic carrier signals. An initiation for a silent period may be understood as a trigger or event that indicates when the backscatter communication device will start absorbing the electromagnetic carrier signals. Electromagnetic carrier signals may be understood as waves that are transmitted through a medium and can be modulated to carry information.

[0016] The electromagnetic carrier signals incident on the backscatter communication device may be transmitted from a source node. The interference may include electromagnetic carrier signals from the source node received at the receiver node via a path other than a path via the backscatter communication device, e.g., via a direct line of sight path and / or multipath propagation.

[0017] The receiver node may then perform the interference cancelling in the electromagnetic carrier signals based on the estimated interference.

[0018] A technical advantage of this disclosure is that it enables reliable and simple determination of interference in the electromagnetic carrier signals received later from the backscatter communication device. By analyzing the silent period, the receiver node can estimate the interference caused by the channel between the source node emitting the electromagnetic carrier signals and the backscatter communication device. This estimation allows for accurate interference cancelling, which improves the overall performance of the communication system.

[0019] In an example, the initiation may cause (in the backscatter device) generation of a prepattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device. The pre-pattern may precede and announce a beginning of the silent period. Alternatively or in addition, the initiation may cause (in the backscatter device) generation of a post-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device. The postpattern may follow and announce an end of the silent period.

[0020] A pre-pattern or a post-pattern may be understood as a pattern that precedes or follows the silent period, respectively. These patterns may include on-periods where the incident electromagnetic carrier signals are reflected at the backscatter communication device, and / or off- periods where the incident electromagnetic carrier signals are absorbed at the backscatter communication device.

[0021] An effect of this arrangement is that the silent period can be reliably identified by the receiver node. This is because the pre-pattern or post-pattern provides a clear indication of when the silent period begins or ends. As a result, the receiver node and the backscatter communication device can be synchronized to ensure accurate transmission and reception of information. This synchronization enables the receiver node to accurately estimate interference in the electromagnetic carrier signals during the silent period.

[0022] In an example, the method may further comprise obtaining at least one property of at least one of the pre-pattern, the post-pattern and the silent period from at least one of: a source node of the electromagnetic carrier signals, based on an identifier of the backscatter communication device, or a network configuration of a communications network in which the backscatter communication device, the receiver node and the source node reside.

[0023] A property of the pre-pattern, the post-pattern or the silent period may be understood as a characteristic that defines one of these patterns or periods, e.g. a duration of the silent period and a bit pattern of the pre- and post-pattern. In some examples, the duration of the silent period may be up to a number of symbol durations of modulation symbols of a modulation used by the backscatter communication device for transmitting information that fit within ten percent of the shortest expected channel coherence time. In some examples, the duration of the silent period may be a number of symbol durations of modulation symbols of a modulation used by the backscatter communication device for transmitting information that fit within a predefined or configurable percentage of the shortest expected channel coherence time. The percentage may be in a range of 5 to 20 percent. For example, the duration of the silent period may be in a range of 1 to 50 symbol durations, e.g. 20, of modulation symbols of the backscatter communication device’s modulation.

[0024] The silent period, optionally including pre- and post-patterns, may precede and announce a transmission of a block of information or data transmitted by the backscatter communication device. The silent period, optionally including pre- and post-patterns, may follow a transmission of a block of information or data transmitted by the backscatter communication device.

[0025] Obtaining such properties from various sources enables the receiver node to accurately determine when the silent period begins and ends.

[0026] The silent period, optionally including pre- and post-patterns, may be inserted in a transmission of a block of information or data transmitted by the backscatter communication device. This may help to maintain synchronization between the receiver node and the backscatter communication device as well as updating the interference estimation in varying environments, for example due to a movement of the receiver node, the source node or the backscatter communication device.

[0027] Also, if a channel varies over time and a data transmission becomes longer than a channel coherence time, the backscatter communication device may transmit the silent period within the transmission.

[0028] In an example, the source node may provide this information, which can be used by the receiver node to obtain properties of the pre-pattern, post-pattern or silent period. Alternatively, the identifier of the backscatter communication device may be used to derive information that enables the receiver node to determine when the silent period begins and ends or how the pre- and post-patterns are configured.

[0029] A network configuration of a communications network may also provide information about the properties of the pre-pattern, post-pattern or silent period, e.g. during registration at the communications network.

[0030] An effect of this arrangement is that it enables the receiver node to accurately estimate interference in the electromagnetic carrier signals during the silent period.

[0031] This arrangement also allows the source node, backscatter communication device and receiver node to operate in a coordinated manner, ensuring that data is transmitted and received accurately.

[0032] In an example, the method may further comprise receiving a request instructing the backscatter communication device to transmit information, e.g., payload data such as sensor data. The method may also include determining the initiation of the silent period based on the request, i.e., the silent period as well as the information transmission maybe triggered by the request. This determination enables the receiver node to accurately estimate interference in the electromagnetic carrier signals during the silent period.

[0033] A request instructing the backscatter communication device to transmit information may be understood as a message that triggers the transmission of data from the backscatter communication device. This request can also be received by the receiver node, which then determines the initiation of the silent period based on this request. The request may also include characteristics of the electromagnetic carrier signals.

[0034] An effect of this arrangement is that interference estimation can be performed on demand of a transmission. By receiving a request instructing the backscatter communication device to transmit information, the receiver node can accurately determine when to estimate interference in the electromagnetic carrier signals. A pre-pattern may also indicate the silent period.

[0035] This arrangement also allows for explicit trigger messages to be avoided. Instead of sending separate trigger messages, the request for information transmission itself can serve as a trigger that initiates the interference estimation process. This reduces the complexity of the system and makes it more efficient.

[0036] In an example, the method may further comprise obtaining a timing of the silent period. The method may also include determining the initiation of the silent period based on the timing, i.e., the timing may be indicative of executing the silent period by the backscatter communication device. This determination enables the receiver node to accurately estimate interference in the electromagnetic carrier signals during the silent period.

[0037] A timing of the silent period may be understood as a schedule or plan that indicates when the backscatter communication device will / shall execute the silent period. Obtaining this timing allows the receiver node to synchronize its operations with those of the backscatter communication device, ensuring that the silent period is monitored accurately.

[0038] An effect of this arrangement is that silent periods can be scheduled to maintain synchronization and interference estimation in varying environments. By obtaining a timing of the silent period, the receiver node can adapt to changes in the environment, such as variations in arrangement of the receiver node, the source node and / or the backscatter communication device, and still maintain accurate interference estimation.

[0039] This arrangement also enables the backscatter communication device to execute the silent period at optimal times, minimizing the impact on data transmission and reception. The scheduling of silent periods allows for efficient use of resources.

[0040] In an example, the method may further comprise receiving a request indicative of the initiation for the silent period from a communications network in which the backscatter communication device, the receiver node and a source node reside.

[0041] A request indicative of the initiation may be understood as a message or signal that triggers the silent period. Receiving this request allows the backscatter communication device to directly perform the silent period, ensuring e.g. that a planned following data transmission is optimized.

[0042] An effect of this arrangement is that it enables direct control of the silent period. By receiving a request from the communications network, the backscatter communication device can initiate the silent period at optimal times, minimizing the impact on data transmission and reception.

[0043] This arrangement also allows for adaptive control of the silent period. In case data transmission has degraded, the communications network can send a request to the backscatter communication device to initiate the silent period, ensuring that interference is minimized and data transmission is improved.

[0044] In addition, this arrangement improves the overall reliability of the system. By receiving a request indicative of the initiation, the backscatter communication device can accurately control the silent period, ensuring that data is transmitted and received accurately.

[0045] An aspect of the present disclosure relates to a method for use in a backscatter communication device configured to transmit information to a receiver node by modulating electromagnetic carrier signals that are incident at the backscatter communication device. The method comprises determining an initiation for a silent period of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device. The method also includes executing the silent period in accordance with the initiation, thereby enabling the receiver node to estimate interference caused by the electromagnetic carrier signals. Determining an initiation for the silent period enables the backscatter communication device to control when the silent period occurs, and how long it lasts. An effect of executing the silent period in accordance with the initiation is that it enables the receiver node to accurately estimate interference caused by the electromagnetic carrier signals. This is because the silent period provides a known time interval during which the electromagnetic carrier signals are not being reflected or re-transmitted by the backscatter communication device, allowing the receiver node to measure and estimate the interference independent from a data / information transmission from the backscatter communication device. An effect may be that this method enables more accurate estimation of interference in wireless communication systems. By determining an initiation for a silent period and executing it accordingly, the backscatter communication device can provide a known time interval during which the electromagnetic carrier signals are not being reflected or re-transmitted, allowing the receiver node to accurately estimate the interference. Additionally, an effect may be that this method enables more efficient use of wireless resources. By controlling when the silent period occurs and how long it lasts, the backscatter communication device can optimize its transmission schedule to minimize interference with other devices in the vicinity, thereby improving overall system performance.

[0046] The method can be inter-related to the above described method for use in the receiver node.

[0047] For example, the initiation may cause generation of a pre-pattern and / or a post-pattern that may precede / announce a beginning of the silent period and follow / announce an end of the silent period, respectively.

[0048] The method may further comprise obtaining at least one property of at least one of the pre-pattern, the post-pattern and the silent period from at least one of: a source node of the electromagnetic carrier signals; based on an identifier of the backscatter communication device; and / or a network configuration of a communications network in which the backscatter communication device, the receiver node and the source node reside.

[0049] Generally, the duration of the silent period may be up to a number of symbol durations of modulation symbols of a modulation of the information that fit within ten percent of the shortest expected channel coherence time.

[0050] The silent period and optionally the pre- and post-patterns may precede and / or announce a transmission of a block of data transmitted by the backscatter communication device. In some examples, the silent period and optionally the pre- and post-patterns may be inserted in a transmission of a block of data transmitted by the backscatter communication device. The silent period and optionally the pre- and post-patterns may also follow a transmission of a block of data transmitted by the backscatter communication device.

[0051] In some examples, method comprises receiving a request to transmit information, and determining the initiation based on the request. The request may include characteristics of the electromagnetic carrier signals.

[0052] In some examples, the method may comprise obtaining a timing, e.g., a schedule, for providing the silent period. The initiation for the silent period may be determined based on the timing. Effects described above in connection with the method for use in the receiver node may similarly apply to the method for use in the inter-related backscatter communication device and will therefore not be repeated.

[0053] In an example, the method may further comprise harvesting energy by absorbing the incident electromagnetic carrier signals during the silent period.

[0054] Harvesting energy by absorbing these signals enables the backscatter communication device to operate without an external power source, reducing its size and increasing its efficiency. In this arrangement, the backscatter communication device may harvest energy during the silent period, when the electromagnetic carrier signals are not being reflected or re-transmitted. This allows the device to replenish its energy reserves, extending its operating lifetime and improving overall system performance.

[0055] An effect of this arrangement is that it enables self-sustaining operation of the backscatter communication device. By harvesting energy from the electromagnetic carrier signals during the silent period, the device can maintain its functionality without relying on external power sources.

[0056] A further aspect of the present disclosure relates to a method for a source node for providing electromagnetic carrier signals for a backscatter communication device configured to transmit information, to a receiver node, by modulating the electromagnetic carrier signals that are incident at the backscatter communication device.

[0057] The method comprises providing for the backscatter communication device at least one property of at least one of a pre-pattern, a post-pattern and a silent period. The backscatter communication device executes the silent period of a predefined duration in accordance with an initiation, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals.

[0058] The initiation also causes generation of at least one of the pre-pattern and the post-pattern. The pre-pattern is a sequence of on-periods and / or off-periods that precedes and announces the beginning of the silent period. The post-pattern is a sequence of on-periods and / or off-periods that follows and announces the end of the silent period.

[0059] A source node may be understood as a device that provides electromagnetic carrier signals for use by other devices, such as backscatter communication devices. Providing properties of the pre-pattern, post-pattern, and silent period enables the source node to control the operation of the backscatter communication device, ensuring that it operates in accordance with its intended functionality.

[0060] An effect of this arrangement is that it enables coordinated operation between the source node, the receiver node, and the backscatter communication device. By providing properties of the pre-pattern, post-pattern, and silent period, the source node can ensure that the receiver node reliably monitors the silent period at optimal times. This arrangement also enables more efficient use of wireless resources.

[0061] In an example, the method may further comprise obtaining the at least one property of the at least one of the pre-pattern, the post-pattern and the silent period from a communications network in which the backscatter communication device, a receiver node receiving the information from the backscatter communication device, and the source node reside.

[0062] Obtaining properties of the pre-pattern, post-pattern, and silent period from the communications network enables the source node to coordinate its operation with other devices in the network, ensuring that they operate in accordance with their intended functionality.

[0063] An aspect of the present disclosure relates to a further method for a source node for providing electromagnetic carrier signals for a backscatter communication device. The method comprises providing for the backscatter communication device a request to transmit information. The backscatter communication device executes a silent period in accordance with an initiation, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling a receiver node to estimate interference of the electromagnetic carrier signals. The initiation is determined based on the request.

[0064] In this arrangement, the initiation is determined based on the request for information / data transmission. This ensures that the silent period is executed at optimal times. An effect of this arrangement is also that it enables coordinated operation between the source node, the receiver node and the backscatter communication device. By determining the initiation based on the request, the source node can ensure that the backscatter communication device operates in accordance with its intended functionality.

[0065] A further aspect of the present disclosure relates to a further method for a source node for providing electromagnetic carrier signals for a backscatter communication device. The method comprises providing for the backscatter communication device a timing for providing a silent period. The backscatter communication device executes the silent period in accordance with an initiation, wherein the silent period is of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling a receiver node to estimate interference of the electromagnetic carrier signals. The initiation is determined based on the timing. This ensures that the silent period is executed at optimal and coordinated times, minimizing interference with other devices in the vicinity.

[0066] An aspect of the present disclosure relates to a further method for a source node for providing electromagnetic carrier signals for a backscatter communication device. The method comprises providing for the backscatter communication device an initiation for executing a silent period of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling a receiver node to estimate interference of the electromagnetic carrier signals. The initiation may be communicated in a trigger message.

[0067] The initiation for executing the silent period may be provided upon receiving a request indicative of the initiation from a communications network in which the backscatter communication device, a receiver node receiving the information from the backscatter communication device, and the source node reside. This may enable direct control of the silent period by the network.

[0068] One aspect of the present disclosure relates to a method for a network node of a communications network in which a backscatter communication device, a receiver node receiving information from the backscatter communication device, and a source node reside. The method comprises providing an initiation to at least one of the source node and the receiver node. The initiation is indicative that the backscatter communication device executes a silent period in accordance with the initiation, wherein the silent period is of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals.

[0069] A network node may be understood as a device that facilitates communication between other devices in a communications network. Providing an initiation to at least one of the source node and the receiver node enables the network node to control the operation of the backscatter communication device, ensuring that it operates in accordance with its intended functionality.

[0070] In this arrangement, the initiation is used to execute the silent period. This ensures that the electromagnetic carrier signals are absorbed at optimal times.

[0071] An effect of this arrangement is that it enables coordinated operation between the source node, the receiver node, and the backscatter communication device. By providing an initiation to at least one of the source node and the receiver node, the network node can control operation of the backscatter communication device. This arrangement may also enable more efficient use of wireless resources.

[0072] In addition or as an alternative, the method may comprise providing at least one property of at least one of a pre-pattern, a post-pattern and a silent period to at least one of the source node and the receiver node. The backscatter communication device executes the silent period of a predefined duration in accordance with an initiation. During the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals. The initiation further causes generation of at least one the pre-pattern and the post-pattern..

[0073] In addition or as an alternative, the method comprises providing a timing to at least one of the source node and the receiver node. As explained above, the source node may also forward the timing to the backscatter communication device. The backscatter communication device executes the silent period of a predefined duration in accordance with the timing.

[0074] A corresponding devices including control circuitry for executing such methods are also disclosed.

[0075] It is to be understood that the features mentioned above and those yet to be explained below may be used not only in the respective combinations indicated, but also in other combinations or in isolation without departing from the scope of the invention.

[0076] BRIEF DESCRIPTION OF THE DRAWINGS

[0077] FIG. 1 schematically illustrates a communication system including multiple devices that implement nodes of a backscatter communication according to various examples.

[0078] FIG. 2 schematically illustrates details of a device according to various examples.

[0079] FIG. 3 schematically illustrates a reference implementation of a radio-frequency circuitry of a communication interface of a backscatter communication device.

[0080] FIG. 4 schematically shows an electromagnetic carrier signals and a modulated electromagnetic carrier signal according to various examples. FIG. 5 is a signaling diagram according to various examples.

[0081] FIG. 6 is a signaling diagram according to further examples.

[0082] FIG. 7 is a flowchart of a method for a receiver node according to various examples.

[0083] FIG. 8 is a flowchart of a method for a backscatter communication device according to various examples.

[0084] FIGs. 9 to 12 are flowcharts of methods for a source node according to various examples.

[0085] FIGs. 13 to 15 are flowcharts of methods for a network node according to various examples.

[0086] DETAILED DESCRIPTION

[0087] Some examples of the present disclosure generally provide for a plurality of circuits or other electrical devices. All references to the circuits and other electrical devices and the functionality provided by each are not intended to be limited to encompassing only what is illustrated and described herein. While particular labels may be assigned to the various circuits or other electrical devices disclosed, such labels are not intended to limit the scope of operation for the circuits and the other electrical devices. Such circuits and other electrical devices may be combined with each other and / or separated in any manner based on the particular type of electrical implementation that is desired. It is recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, a graphics processor unit (GPU), integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, any one or more of the electrical devices may be configured to execute a program code that is embodied in a non-transitory computer readable medium programmed to perform any number of the functions as disclosed.

[0088] In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of embodiments is not to be taken in a limiting sense. The scope of the invention is not intended to be limited by the embodiments described hereinafter or by the drawings, which are taken to be illustrative only. The drawings are to be regarded as being schematic representations and elements illustrated in the drawings are not necessarily shown to scale. Rather, the various elements are represented such that their function and general purpose become apparent to a person skilled in the art. Any connection or coupling between functional blocks, devices, components, or other physical or functional units shown in the drawings or described herein may also be implemented by an indirect connection or coupling. A coupling between components may also be established over a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof.

[0089] Hereinafter, techniques for implementing a backscatter communication are disclosed. In a backscatter communication, a backscatter communication device of the backscatter communication modifies an excitation signal received incident from a transmitting source node of the backscatter communication, to thereby convey data to a receiver node of the backscatter communication. The transmitting source node transmits the excitation signal, typically a continuous wave, towards the backscatter communication device. This excitation signal serves as a carrier for the information that the backscatter communication device intends to transmit. The backscatter communication device modulates the incident excitation signal. Typically, the modulation used is ON-OFF-keying (OOK). OOK modulation is achieved by switching the impedance of the radio-frequency (RF) interface at the backscatter communication device between two states. These states correspond to the binary values, e.g. 0 and 1 , in the informationcarrying signal departing from the backscatter communication device. This varies the amplitude of the information-carrying signal between an OFF-state and an ON-state. Binary frequency shift keying (BFSK) may also be used as modulation scheme by switching the impedance of the radiofrequency (RF) interface at the backscatter communication device between two states with two different speeds. The receiver node then detects these variations in the signal amplitude of the information-carrying signal. The information-carrying signal is demodulated to retrieve the information carried by the information-carrying signal.

[0090] According to various examples, the (hardware) device implementing the (functionality of the) backscatter communication device is configured to harvest and store energy from the RF spectrum. More specifically, the energy can be harvested from an excitation signal. For this, the device may include a power-harvesting interface and an energy storage, e.g. a rechargeable battery or a capacitor. This enables the device to store a fraction of the impinging RF power of the excitation signal. Then, this stored power can be used for operating the device and optionally power-boosting the information-carrying signal.

[0091] Generally, there are two primary configurations for backscatter systems: mono-static and bi-static. In a mono-static configuration, the source node and receiver node are co-located, meaning they share the same antenna or are situated in close proximity. This setup simplifies system design and deployment but may limit the range and flexibility of the system. On the other hand, bi-static configurations involve separate source nodes and receiver nodes, allowing for greater flexibility in deployment and potentially improving range and reliability.

[0092] In addition to these two primary configurations, backscatter systems can also be categorized based on the type of RF source used: dedicated or ambient. Dedicated backscatter involves a purpose-built source node that sends an RF signal specifically designed for backscatter communication. This approach provides greater control over the transmitted signal and can result in better system performance. In contrast, ambient backscatter leverages existing environmental RF sources, such as television broadcasts, cellular networks, or Wi-Fi signals, to enable communication. While this approach eliminates the need for a dedicated transmitter, it may introduce challenges related to signal quality and reliability.

[0093] The focus of the present disclosure is on bi-static dedicated backscatter communication systems, which combine the advantages of separate source and receiver nodes with the benefits of purpose-built RF sources. By utilizing a dedicated transmitter and optimizing system design, bi-static dedicated backscatter has the potential to achieve improved range, reliability, and performance compared to other forms of backscatter communication. However, the disclosed techniques may be similarly applied on bi-static ambient backscatter and also on mono-static backscatter.

[0094] FIG. 1 schematically illustrates a communication system 100 (bi-static backscatter) according to various examples. The bi-static communication system 100 includes a device 110, a device 120, and a device 130.

[0095] In the scenario of FIG. 1 , the device 110 - e.g., a base station (BS) of a cellular network implementing a Third Generation Partnership Project (3GPP) protocol or a terminal / user equipment (UE) or a repeater node - implements a source node of a backscatter communication 140. The device 110 includes a transmitter 114 and a control circuitry 112. The device 110 may include further components, for example a receiver, a user interface, a power supply or a battery. However, in view of the backscatter communication described below, these components are omitted for clarity reasons. Furthermore, in the following, the device 110 will be referred to as source node 110. The source node 110 transmits, e.g. via the transmitter 114 and under control of the control circuitry 112, an electromagnetic carrier signal acting as an excitation signal 142 of the backscatter communication 140 to the device 120. However, the electromagnetic carrier signal may also propagate in other directions, e.g. as signal 160 to the device 130.

[0096] The device 120 - e.g., an loT device such as a smartwatch, a smart-meter, an inventory tracker, etc. - implements a backscatter communication device of the backscatter communication 140. The device 120 includes a backscatter communication (BSC) RF circuitry 124 and a control circuitry 122. The device 120 may include further components, for example a receiver, a sensor, and / or an energy storage such as a capacitor or battery. However, in view of the backscatter communication described below, these components are omitted for clarity reasons. Furthermore, in the following, the device 120 will referred to as BSC device 120. The excitation signal 142 is reflected and modulated, e.g. by the BSC RF circuitry 124 under control of the control circuitry 122, to carry information, which yields an information-carrying signal 144.

[0097] The device 130 - e.g., a base station (BS) of a cellular network implementing a Third Generation Partnership Project (3GPP) protocol or a terminal / user equipment (UE) or a repeater node - implements a receiver node of the backscatter communication 140. The device 130 includes a receiver 134 and a control circuitry 132. The device 130 may include further components, for example a transmitter, a user interface, a power supply or a battery. However, in view of the backscatter communication described below, these components are omitted for clarity reasons. Furthermore, in the following, the device 130 will referred to as receiver node 130. The receiver node 130 is configured to receive, e.g. via the receiver 134 and under control of the control circuitry 132, the information-carrying signal 144 and to demodulate the informationcarrying signal 144 to retrieve the information from the BSC device 120.

[0098] The communication system 100 may comprise further components, such as a device 150, for example a network node - e.g., a base station (BS) of a cellular network implementing a Third Generation Partnership Project (3GPP) protocol or a management node of the communication system 100 - communicating with the devices 110 and 130 as indicated by arrows 172 and 174. The device 150 may implement a transceiver 154 and control circuitry 152. The device 150 may control operation of the devices 110, 120 and 130. In the following, the device 150 will also referred to as network node 150. Devices 150 and 110 may be integrally formed, for example as a base station.

[0099] FIG. 1 is only one example configuration of a communication system 100 that can benefit from the techniques disclosed herein. Another scenario, e.g. a bi-static ambient backscatter scenario may also benefit from the techniques disclosed herein as will become apparent from the following description.

[0100] FIG. 2 schematically illustrates a device 200 according to various examples. For example, the device 200 may implement any of the devices 110, 120, 130, 150 previously discussed in connection with FIG. 1.

[0101] The device 200 includes a processor 202, a communication interface 206, and a memory 204. Communication over a radio spectrum is possible via the communication interface 206. For example, an active wireless transmission of one or more excitation signals of a backscatter communication can be implemented. It would also be possible for a received signal to be reflected in a modulated manner, as previously discussed in connection with the BSC device 120. It would also be possible to receive and demodulate an information-carrying signal. The communication interface 206 may or may not include an energy storage such as a battery; and / or may or may not include a power-harvesting interface. In some scenarios, the communication interface 206 may be powered from a battery or energy storage or energy supply of the device 200, e.g., also powering the processor 202 for general device operations. The communication interface 206 may not only implement physical layer functionality, i.e., spectrum access, but may also implement higher layers of a transmission protocol stack, e.g., to provide control messages or to receive control messages. The processor 202 may load program code from the memory 204 and execute the program code. Upon executing the program code, the processor 202 may be configured to: implement the functionality of one or more nodes / devices of a backscatter communication; implement a source node of a backscatter communication; implement a BSC device of a backscatter communication; implement a receiver node of a backscatter communication; transmit an excitation signal; receive an excitation signal; modulate and reflect an excitation signal, to obtain an information-carrying signal; transmit the information-carrying signal; receive an information-carrying signal; demodulate an information-carrying signal; and so on.

[0102] FIG. 3 illustrates an RF circuitry 300 of a device capable of implementing a backscatter node, such as the BSC RF circuitry 124 of FIG. 1 , of a backscatter communication according to various examples. The RF circuitry 300 enables, e.g., a passive backscatter communication. For this, the excitation signal 142, e.g. an information-carrying signal, obtained from the source node 110 via an antenna circuit 306 is either absorbed (OFF-duration) or reflected (ON-duration). Reflection can be achieved by setting the switch 308 to the position in which it is connected to the impedance-mismatched load 302. In this scenario, there is an impedance mismatch between the antenna circuitry 306 and the load 302, leading to the reflection. Absorption can be achieved by setting the switch 308 to the position in which it is connected to the impedance-matched load 304. In this scenario, there is an impedance match between the antenna circuitry 306 and the load 304, leading to the absorption. The switch is actuated by a circuitry 310 that may apply an OOK modulation scheme based on an incoming bitstream 312 that encodes the information to be communicated.

[0103] Returning to FIG. 1 , the receiver node 130 receives a signal y[n] including the informationcarrying signal 144 and the signal 160 which may interfere the reception of the informationcarrying signal 144. The signal y[n] at the backscatter receiver node 130 may be modeled, in discrete time, as y[n] = / ib[n] / iy[n]Pd[n]s[n] + Zi,[n]s[n] + w[n] where the first summand is the received backscattered signal 144, the second summand is the interfering signal 160 directly from the source node 110, and the last summand is the receiver noise of the receiver node 130. Below a brief description of all parameters in the above equation is given: s[n] signal 142 / 160 from the source node 110; hf[n] transfer function of the forward channel between the source node 110 and the BSC device 120; hb[n] transfer function of the BSC channel between the BSC device 120 and the receiver node 130;

[0104] Zi,[n] transfer function of the interference channel between the source node 110 and the receiver node 130;

[0105] Pd[n] e {0,1} BSC pattern modulated on the excitation signal 142, d e {0,1} w[n] receiver noise;

[0106] The signal 144 received from the BSC device 120, i.e., the first summand in the equation, has passed through two wireless channels, hb[n] and hf[n], and may additionally be attenuated due to reflection at the BSC device 120. This means that in most practical cases the attenuation level of the modulated signal 144 from the BSC device 120 is higher than that of the interfering signal 160. This is particularly the case, if the BSC RF circuitry 124 of the BSC device 120 is fully passive, i.e., no amplifier is used in the BSC RF circuitry 124.

[0107] When the BSC device 120 is in an absorption state, i.e. the signal 142 is substantially absorbed and the power of the signal 144 is substantially zero, the receiver node 130 substantially receives only the interfering signal 160, i.e. y[n] = Zi,[n]s[n] + w[n]

[0108] In the present disclosure, a binary encoding of data from the BSC device 120 is assumed, wherein a binary value of zero 'O' is encoded by the signal 142, which is substantially absorbed, and a binary value of one 'T is encoded by the signal 142, which is substantially reflected. However, this is only an example and other encodings may be used, such as the inverse of the above encoding or a trinary encoding, Manchester encoding, Miller encoding.

[0109] According to the present disclosure, a silent period may be included in the informationcarrying signal 144, e.g. at the beginning of the information-carrying signal. The signal s[n] may be a signal known to the receiver node 130, e.g., a known modulated or unmodulated single-tone, multi-tone, or OFDM signal. The silent period may be a period where, according to the above definition, only zeros are generated by the BSC device 120, i.e. the signal 142 is substantially absorbed and the power of the signal 144 is substantially zero. The silent period may have a predefined length L. The receiver node 130 can estimate the interference channel / i n] based on the signal 160 during the silent period.

[0110] The silent period may also indicate the start of the information in the signal 144, may help synchronization and may be used for energy harvesting purposes.

[0111] The estimated interference channel / i n] may then be used during the information transmission period. The interfering signal 160 can be calculated / estimated using the interference channel estimation / i n]. The receiver node 130 may use this to cancel the interference and decode the information in the received backscattered signal 144.

[0112] FIG. 4 illustrates examples of the signal 160 and the backscattered signal 144. Each diagram illustrates the signal power over time. In the example of FIG. 4, the signal 160 is illustrated as an unmodulated RF signal. However, this is only an example and in other examples the signal 160 may be a modulated signal. A frequency of the signal 160 may be much higher than a symbol rate of the backscattered signal 140. The symbol rate of the backscattered signal 140 is indicated by the division of the time-axis. For example, the signal 160 may be a 3GPP or WLAN signal with a frequency in the GHz range. For example, the backscattered signal 140 may have a symbol rate in the range of a few hundred to a few hundred thousand symbols per second. As explained in connection with FIG. 1 , and as further illustrated in FIG. 4, the excitation signal 142 may essentially correspond to the signal 160. The BSC device 120 modulates the excitation signal 142 thus generating the backscattered signal 144 which may have a significantly lower power than the excitation signal 142 and the signal 160. At the receiver node 130, a combined signal including the backscattered signal 144 and the signal 160 is received.

[0113] FIG. 4 also illustrates the above-mentioned silent period 424 in the backscattered signal 144. In this example, the silent period 424 has the length of ten symbols, i.e. ten zeros. However, this is only an example and the silent period 424 may have a different length, for example a number of symbols that corresponds to ten percent of the shortest expected coherence time of the channel. For example, in some examples, the silent period may not be a continuous stream of zeros, but may be included in a predefined pattern of ones and zeros, such as '10001101110000', such that the receiving node 134 can estimate the interference channel during the zeros of the predefined pattern.

[0114] In addition, a pre-pattern 422 and a post pattern 426 may be included in the backscattered signal 144 that indicate the beginning and the ending of the silent period 424. In the illustrated example, the pre-pattern 422 and the post pattern 426 each have a length of three symbols. The pre-pattern 422 may be considered as a sequence of binary values '10T and the post pattern 426 may be considered as a sequence of binary values '110'. However, these are only examples and the pre- and post-patterns 422 and 426 may have other lengths and other properties. For example, the pre-pattern and post-pattern may be selected from sequences with good auto- and cross- correlation properties. The pre-pattern may be encoded to be resistant to the interference signal received directly at the receiver device. Transmission of the (payload) data of the backscattered signal 144 may start after the post-pattern 426 and is indicated in the diagram by reference number 428. The silent period 424 and optionally the pre-pattern and post-pattern, 422 and 426, respectively, may also be transmitted within a data payload if the total transmission length of the payload period becomes larger than the shortest expected coherence time of the channel.

[0115] FIG. 5 illustrates an example, in which the interference estimation based on the silent period 424 is managed by the network node 150.

[0116] The network node 150, for example a gNB, transmits a trigger message 502 to the source node 110 and a trigger message 504 to the receiver node 130. The trigger message may also be transmitted to the BSC device 120. The trigger messages 502, 504 may indicate that the interference estimation starts immediately or may indicate a point in time or a schedule for the interference estimation to start. In addition, the trigger messages 502, 504 may indicate configurations regarding the interference estimation, for example a duration of the silent period, a pattern or length of a pre-pattern and / or a pattern or length of a post-pattern.

[0117] Upon receiving the trigger message 502, the source node 110 transmits radiofrequency (RF) source signals s[n] 506, i.e. electromagnetic carrier signals acting as excitation signal 142 that can be absorbed or reflected at the BSC device 120. As indicated in FIG. 5, signal 506 may reach the receiver node 130 (see also signal 160 in FIG. 1) and the BSC device 120 (see also signal 142 in FIG. 1).

[0118] The signal 506 may be indicative of the time of occurrence of the interference estimation, e.g. immediately or at a specific point in time. In addition, the signal 506 may indicate configurations regarding the interference estimation, for example a duration of the silent period, a pattern or length of a pre-pattern and / or a pattern or length of a post-pattern. The time of occurrence and the configurations regarding the interference estimation may correspond to those received by the trigger message 502.

[0119] Next, the BSC device 120 initiates a silent period, that is, the BSC device 120 is configured such that the incident electromagnetic carrier signal 506 is substantially absorbed and, consequently, substantially no reflected signal of the carrier signal 506 reaches the receiver node 130. In FIG. 5, the non-reflected signal from the BSC device 120 to the receiver node 130 is shown as a silent signal 508, which is a dashed arrow, because it is a substantially non-existent signal.

[0120] However, the signal 506 may still reach the receiver node 130 (see also signal 160 in FIG. 1). In box 510, the receiver node 130 can estimate the interference channel / i n] based on the signal 506. A duration of the silent period may be insufficient to enable the receiver node 130 to estimate the interference channel. For example, the silent period may be as long as a number of symbol durations of modulation symbols of a modulation used by the BSC device 120 for transmitting information that can fit within five, fifteen or preferably ten percent of the shortest expected coherence time of the channel, for example ten symbol durations as illustrated in FIG. 4.

[0121] The silent signal 508 may be preceded by the pre-pattern 422 and / or followed by the postpattern 426 as discussed above in connection with FIG. 4. The pre-pattern 422 and / or the post- pattern 426 may be used by the receiver node 130 to synchronize with the symbol timing of the data 428 from the BSC device 120 that will follow, and / or may indicate to the receiver node 130 the beginning of the data 428 from the BSC device 120 that will follow.

[0122] The BSC device 120 may harvest the energy absorbed during the silent period and may store the energy in a battery or capacitor for powering the device BSC device 120, for example the control circuitry 122 and the BSC RF circuitry 124.

[0123] After the silent period and the interference estimation 510, BSC device 120 may transmit data to the receiver node 130. For transmitting data, the BSC device 120 receives a further excitation signal s[n] 512 from the source node 110 and generates by modulation, i.e., reflection or absorption, a BSC signal 514 which is received at the receiver node 130. At the same time, the excitation signal 512 reaches the receiver node 130 as an interfering signal. The receiver node 130 may use at box 516 the estimation of the interference channel to cancel the interference caused by the directly received excitation signal 512, and may decode at box 518 the data in the received BSC signal 514.

[0124] As discussed above, the silent signal 508 may be a time period of predefined duration during which the electromagnetic carrier signals are absorbed at the BSC device 120, i.e., a continuous silent period. In various examples, the silent signal 508 may be included in a known signal with silent periods, such as '1000001010111000000'. The silent signal 508 may be combined with a preceding pre-pattern and / or a following post-pattern as discussed above. Configuration of the silent signal 508 may be provided by the source node 110 or by network configuration of the communications network in which the BSC device 120, the receiver node 130 and the source node 110 reside. In some examples, the configuration of the silent signal 508 may be based on an identifier (ID) of the BSC device 120. For example, the silent signal 508 may be included in a signal containing a pre-pattern, followed by a binary coded ID of the BSC device 120, followed by a predefined number of zeros as silent period and a post-pattern.

[0125] In various examples, the silent signal 508 may be included autonomously by the BSC device 120 based on a predefined timing schedule. The timing schedule may be predefined within the network in which the devices 120 and 130 reside, and therefore may also be known to the receiver node 130. However, in other examples, the timing schedule may not be known to the receiver node 130, and the receiver node 130 may identify the silent signal 508 based on a particular pre-pattern at the beginning of the silent signal 508.

[0126] In a further example, the silent period can be part of a fixed-by-specification pre-pattern, a so-called preamble, preceding a transmission with multiple purposes. For example, the preamble may indicate the start of a BSC transmission and may provide timing synchronization. The receiver node 130 performing interference estimation and cancellation may need to know when a particular BSC device 120 transmits its preamble. If the preamble for interference estimation is the same as the preamble without interference estimation (i.e. only indicating the start of a BSC transmission and / or providing timing synchronization), an interference estimation may not necessarily be initiated. Interference estimation might not always be needed, e.g., if the receiver node 130 has determined that the environment and therefore the interfering channel has not significantly changed since the previous interference estimation has been performed. Interference estimation may be costly in terms of processing and power and may therefore be performed only on demand, in particular in mobile battery powered devices. For example, the trigger 504 may contain configurations for how often the interference estimation is to be performed, or it may instruct the receiver node 130 to perform the interference estimation for a particular BSC device 120.

[0127] In various example, the BSC device 120 may be requested to transmit information. E.g., an loT device including a sensor and a BSC RF circuitry 124 may be requested to provide data including measurement results from the sensor, e.g. consumption of electrical power or gas. FIG. 6 illustrates a corresponding exemplary signaling diagram. The sensor reading may be triggered by a network node, for example device 150 such as a base station. The network node 150 transmits a trigger 602 for a BSC transmission to the source node 110, and a trigger 604 to the receiver node 130. The trigger may also be received by the BSC device to turn on its BSC RF circuitry 124.

[0128] Upon receiving the trigger 602, the source node 110 transmits a radiofrequency (RF) source signal s[n] 606, i.e. an electromagnetic carrier signal acting as excitation signal 142 that can be absorbed or reflected at the BSC device 120. The signal 606 may include an explicit indication for the BSC device 120 to transmit information. In some examples, the fact that the signal 606 is present indicates to the BSC device 120 that information is to be transmitted or at least can be transmitted.

[0129] As indicated in FIG. 6, signal 606 may reach the receiver node 130 (see also signal 160 in FIG. 1) and the BSC device 120 (see also signal 142 in FIG. 1).

[0130] Next, the BSC device 120 may initiate a silent period, e.g. upon receiving the explicit indication included in signal 606 or upon detecting the presence of the signal 606. During the silent period, the BSC device 120 configures its BSC RF circuitry 124 such that the incident electromagnetic carrier signal 606 is substantially absorbed and, consequently, substantially no reflected signal of the carrier signal 606 reaches the receiver node 130. In FIG. 6, the non-reflected signal from the BSC device 120 to the receiver node 130 is shown as silent signal 508, which is a dashed arrow because it is a substantially non-existent signal.

[0131] As described above in connection with FIG. 5, the silent signal 508 may be preceded by the pre-pattern 422 and / or followed by the post-pattern 426. Furthermore, the BSC device 120 may harvest the energy absorbed during the silent period.

[0132] Further signaling 512, 514 and processing 510, 516, 518 may be essentially the same as described above in connection with FIG. 5 and is therefore not repeated.

[0133] To sum up, configurable parameters of the silent signal 508 may include a duration of the silent period; a presence, length and pattern of the pre-pattern; a presence, length and pattern of the post pattern; and / or a time occasion for generating the silent signal 508, 608. In some examples, at least some of these parameters may be predefined in the network. In some examples, at least some of these parameters may be defined for each BSC device 120, for example based on a device ID or during registration or installation of the BSC device 120. In some examples, at least some of these parameters may be configured by the source node 110, for example via signal 506 or 606. A combination of the above described ways for configuration may be possible. To enable the interference estimation in box 510, the receiver node 130 may need to know the timing of the silent signal 508, such as a starting time and duration. In some examples, these parameters may be predefined or configured. In some examples, the starting time may be determined based on a timing schedule or trigger event. The starting time may further be determined based on the above described configuration options.

[0134] As described above, in some examples, the silent period may precede a data transmission, such as a data block transmitted from the BSC device 120 to the receiver node 130. In further examples, the silent period may follow a transmission of a data block. In some examples, the silent period may be inserted in a data block transmission. The silent period may be identified based on a specific preamble, the above pre-pattern and / or the above post pattern.

[0135] FIG. 7 is a flowchart 700 of a method according to various examples. FIG. 7 generally relates to implementation of a backscatter communication. FIG. 7 specifically relates to an interference estimation and canceling for backscatter communications executed by one or more nodes.

[0136] The method of FIG. 7 can be executed by a receiver node. The receiver node may be implemented by a user equipment, such as a user device of a cellular network. The receiver node may be implemented by a network node, such as a base station of a cellular network. For example, the method can be executed by a control circuitry of the node of the cellular network. For instance, the method can be executed by a processor upon loading and executing program code that is stored in a memory. For example, the method of FIG. 7 may be executed by a node that is located in a core network of the cellular network. The node may be the device 130 of FIG. 1.

[0137] In optional step 702, the receiver node obtains properties of the silent period from various sources such as the backscatter communication device, the network node, or other nodes in the communications network. The properties obtained may include the duration of the silent period, as well as the timing of the silent period. Additionally, the receiver node may obtain information about any pre-pattern or post-pattern that precedes or follows the silent period.

[0138] The receiver node may obtain this information through various means, such as receiving a message from the network node such as device 150, receiving a message addressed to the BSC device 120, querying a database, based on an identifier of the BSC device, or using other methods. The properties obtained in this step are used to inform the receiver node's subsequent actions and ensure that it is properly synchronized with the backscatter communication device. For example, in optional step 704, the receiver node 130 receives a request from the network node 150 or the source node 110 addressed to the BSC device 120 to initiate the silent period. The request may include characteristics of the electromagnetic carrier signals, such as their frequency and modulation scheme, as well as information about the BSC device 120, e.g. the BSC identifier. In further examples, the receiver node 130 receives a request from the network node 150 or the source node 110 addressed to the BSC device 120 to transmit information, e.g. transmit a data block. This request may, e.g. depending on the general configurations regarding the silent period, implicitly initiate the silent period. In optional step 706, the receiver node 130 may receive timing information for the silent period, e.g. from the network node 150. This timing information may include when the silent period starts and ends, as well as how long it lasts, if it precedes a block of data, follows a block of data and / or is inserted into a block of data from the BSC device.

[0139] The receiver node may receive this timing information through various means, such as receiving a message from the network node, querying a database, or using other methods. The database may be within the receiver node and preconfigured, for example by network configuration, or may be provided in a management function of the network and accessible via the communication network. The timing information obtained in this step is used to inform the receiver node's subsequent actions.

[0140] In step 708, the receiver node determines the initiation of the silent period based on the request and / or timing information received in previous steps. The initiation indicates when the BSC device will execute the silent period, during which the electromagnetic carrier signals are absorbed at the backscatter communication device.

[0141] The receiver node may determine the initiation using various methods, such as analyzing the request and / or timing information, querying a database or other nodes in the communications network, or using pre-programmed logic or rules. The determination of the initiation may ensure that the receiver node is properly synchronized with the BSC device.

[0142] In step 710, the receiver node estimates interference caused by the electromagnetic carrier signals from the source node during the silent period. This estimation may be based on various methods, such as analyzing the received signal during the silent period and / or using preprogrammed models or algorithms to estimate the channel characteristics of the radio channel between the source node 110 and the receiver node 130.

[0143] The estimated interference is crucial in enabling the receiver node 130 to cancel interference and decode pattern information in the received backscattered signal. The accuracy of the estimation directly affects the quality of the decoded signal.

[0144] In optional step 712, the receiver node 130 receives information from the BSC device 120 after the silent period. This information may include data or other types of signals modulated onto the electromagnetic carrier signals.

[0145] In optional step 714, the receiver node 130 cancels interference in the received data or signal based on the estimated interference calculated based on the silent period. This cancellation may be done using various methods, such as subtracting the estimated interference from the received signal or using pre-programmed algorithms or logic to remove interference.

[0146] The cancelled interference enables the receiver node 130 to accurately decode information in the received backscattered signal. The quality of the decoded signal directly affects the overall performance of the communication between the BSC device 120 and the receiver node 130.

[0147] FIG. 8 is a flowchart 800 of a method according to various examples. FIG. 8 generally relates to implementation of a backscatter communication. FIG. 8 specifically relates to an interference estimation and canceling for backscatter communications executed by one or more nodes. The method of FIG. 8 can be executed by a BSC device. The BSC device may be implemented by an an loT device such as a smartwatch, a smart-meter, an inventory tracker. For example, the method can be executed by a control circuitry of the BSC device. For instance, the method can be executed by a processor upon loading and executing program code that is stored in a memory. For example, the method of FIG. 8 may be executed by a BSC device that is located in a core network of the cellular network. The BSC device may be the device 120 of FIG. 1.

[0148] In optional step 802, the BSC device obtains properties of the silent period from various sources such as the network node 150 or other nodes in the communications network such as the source node 110. The properties obtained may include the duration of the silent period as well as the timing of the silent period.

[0149] The BSC device may obtain this information through various means, such as receiving a message from the network node or querying a database. This step is similar to Step 702 in the receiver node method, where the receiver node also obtains properties of the silent period.

[0150] For example, in optional step 804, the BSC device may receive from the source node 110 or the network node 150 a request to initiate the silent period. The request may include characteristics of the electromagnetic carrier signals, such as their frequency and modulation scheme. This step is similar to Step 704 in the receiver node method.

[0151] In some examples, in optional step 806, the BSC device receives timing information for the silent period from the source node 110 or the network node 150. This timing information may include when the silent period starts and ends, as well as how long it lasts. The timing information may include a timing schedule or instructions to include the silent period before, in between, or after a transmission of a data block.

[0152] This step may be similar to Step 706 in the receiver node 130 method, where the receiver node also receives timing information for the silent period.

[0153] In step 808, the BSC device determines the initiation of the silent period based on the request and / or timing information received in previous steps. The initiation indicates when the BSC device will / shall execute the silent period, during which the electromagnetic carrier signals are absorbed at the backscatter communication device.

[0154] The BSC device may determine the initiation using various methods, such as analyzing the request and / or timing information or using pre-programmed logic or rules or schedules. This step is similar to Step 708 in the receiver node method, where the receiver node also determines the initiation of the silent period.

[0155] In step 810, the BSC device executes the silent period by absorbing the electromagnetic carrier signals at the backscatter communication device. During this time, the receiver node can estimate interference caused by the electromagnetic carrier signals other than from the BSC device, e.g. from the source node 110. This estimation may be used afterwards for canceling interference in electromagnetic carrier signals during the reception from the BSC device.

[0156] The execution of the silent period may enable the receiver node 130 to accurately decode information in the received backscattered signal from the BSC device 120. The duration of the silent period may directly affect the quality of the estimation and therefore of the decoded signal. In optional step 812, the BSC device 120 transmits information modulated onto the electromagnetic carrier signals after the silent period. This information may include data or other types of signals.

[0157] The method 900 of FIG. 9 can be executed by a source node. The source node may be implemented by a user equipment, such as a user device of a cellular network. The source node may be implemented by a network node, such as a base station of a cellular network. For example, the method can be executed by a control circuitry of the node of the cellular network. For instance, the method can be executed by a processor upon loading and executing program code that is stored in a memory. For example, the method of FIG. 9 may be executed by a node that is located in a core network of the cellular network. The node may be the source node 110 of FIG. 1.

[0158] In optional step 902, the source node 110 obtains properties of the silent period from various sources such as the network node 150 or other nodes in the communications network. The properties obtained may include the duration of the silent period as well as the timing of the silent period, such as when it starts and ends and pre- and post-patterns.

[0159] The source node may obtain this information through various means, such as receiving a message from the network node or querying a database. This step is similar to Step 702 in the receiver node method, where the receiver node also obtains properties of the silent period. In step 904, the source node 110 provides the obtained properties of the silent period to the BSC device 120 and / or the receiver node 130. The provided information may include the duration of the silent period as well as the timing of the silent period, such as when it starts and ends and pre- and post-patterns.

[0160] The source node 110 may provide this information through various means, such as sending a message to the backscatter communication device or receiver node. This step may enable the BSC device 120 to execute the silent period in synchronization with the receiver node 130, which is necessary for accurate decoding of information.

[0161] For example, when the source node 110 provides the properties of the silent period to the BSC device 120, it enables the BSC device 120 to determine the initiation of the silent period and execute it accordingly, as described in steps 808 and 810 of the BSC device method 800. Similarly, when the source node 110 provides this information to the receiver node 130, it enables the receiver node 130 to estimate interference caused by the electromagnetic carrier signals during the silent period and cancel it in the received signal, as described in steps 710 and 712 of the receiver node method 700.

[0162] The method 1000 of FIG. 10 can also be executed by a source node. The source node may be implemented by a user equipment, such as a user device of a cellular network, or by a network node, such as a base station of a cellular network, see above.

[0163] In step 1002, the source node 110 provides a request for information transmission to the BSC device 120 and / or the receiver node 130, e.g., based on a request from the network or based on a schedule. The source node 110 may provide this request through various means, such as sending a message to the BSC device 120 or receiver node 130. This step may initiate the process of transmitting information from the BSC device 120 to the receiver node 130. When the source node 110 provides the request for information transmission, this may trigger the BSC device 120 to initiate the silent period and transmit information modulated onto the electromagnetic carrier signals. For example, this step corresponds to step 804 in the BSC device method, where the BSC device determines the initiation of the silent period based on the request.

[0164] The receiver node 130 also plays a role in this process, as it must receive the transmitted information and estimate interference caused by the electromagnetic carrier signals during the silent period. For example, this step corresponds to step 704 in the receiver node method, where the receiver node 130 receives the request to initiate monitoring the silent period and estimates interference in the received signal.

[0165] By providing the request for information transmission, the source node 110 initiates the process of transmitting information from the BSC device 120 to the receiver node 130, and enables accurate decoding of pattern information in the communications system.

[0166] Further, the method 1100 of FIG. 11 can be executed by a source node. In step 1102, the source node 110 may provide a timing for providing a silent period to, for example, the BSC device 120 and / or the receiver node 130. Aspects with respect to such timing configuration have been previously discussed in connection with FIG. 7, step 706, and FIG. 8, step 806.

[0167] Further, the 1200 method of FIG. 12 can be executed by a source node. In optional step 1202, the source node 110 may obtain a request for a silent period from the network node 150 or other nodes in the communications network. The request may include information about the desired duration and timing of the silent period.

[0168] The source node 110 may obtain this request through various means, such as receiving a message from the network node 150 or querying a database. This step is similar to Step 702 in the receiver node method, where the receiver node 130 also obtains properties of the silent period.

[0169] In step 1204, the source node 110 provides the obtained request for the silent period to the BSC device 120 and optionally to the receiver node 130. The provided information may include the desired duration and timing of the silent period.

[0170] The source node 110 may provide this information through various means, such as sending a message to the BSC device 120 or receiver node 130.

[0171] When the source node 110 provides the request for the silent period, it triggers the BSC device 120 to initiate the silent period and optionally to transmit information. For example, this step corresponds to Step 808 in the backscatter communication device method, where the BSC device 120 determines the initiation of the silent period based on the request.

[0172] The receiver node also plays a role in this process, as it must receive the transmitted information and estimate interference caused by the electromagnetic carrier signals during the silent period. For example, this step corresponds to step 710 in the receiver node method, where the receiver node estimates interference and cancels it in the received signal.

[0173] Generally, the source nodes performing the methods described in FIGs. 9 to 12 may be implemented by separate devices or by a common device such as one or more devices 110, e.g. one or more user equipment(s) or gNB(s). The method 1300 of FIG. 13 can be executed by a network node. The network node may be implemented by a base station, such as a gNB, of a cellular network. For example, the method 1300 can be executed by a control circuitry of the node of the cellular network. For instance, the method can be executed by a processor upon loading and executing program code that is stored in a memory. For example, the method of FIG. 13 may be executed by a node that is located in a core network of the cellular network. The node may be the device 150 of FIG. 1 . The node may be a management node, i.e., execute a management function for managing a plurality of BSC devices and nodes in the network, such as the receiver node 130 and / or the source node 110.

[0174] In step 1302, the network node 150 provides a request for a silent period to at least one of the source node 110, the BSC device 120 and the receiver node 130. The provided information may include the desired duration and timing of the silent period as well as information on pre- and post-patterns.

[0175] The network node 150 may provide this information through various means, such as sending a message to the source node 110, the BSC device 120 or receiver node 130. In some examples, a message is sent to the source node 110, and the source node 110 forwards this message to the BSC device 120.

[0176] When the network node 150 provides the request for the silent period, it may trigger the source node 110 to provide a corresponding request to the BSC device 120, as described in step 1204 of the source node method 1200. The BSC device 120 can then initiate the silent period based on the request, as described in step 808 of the BSC device method 800.

[0177] The receiver node 130 also plays a role in this process, as it may monitor the silent period and estimate interference caused by the electromagnetic carrier signals during the silent period, as described in Step 710 of the receiver node method.

[0178] A further method 1400 shown in FIG. 14 that can also be executed by the network node 150.

[0179] In step 1402, the network node 150 provides properties of the silent period to at least one of the source node 110 and the receiver node 130. The provided information may include the duration and timing of the silent period.

[0180] The network node 150 may provide this information through various means, such as sending a message to the source node 110 or receiver node 130. When the network node 150 provides the properties of the silent period, it enables the source node 110 to provide them to the BSC device 120, as described in Step 904 of the source node method 900. The BSC device 120 can then initiate the silent period based on the provided properties, as described in Step 808 of the BSC device method 800.

[0181] The receiver node may also receive the transmitted information and may estimate interference caused by the electromagnetic carrier signals during the silent period, as described in Step 710 of the receiver node method 700. The receiver node may use the properties of the silent period to accurately monitor the silent period for estimating the interference and cancelling it in the received signal.

[0182] A further method 1500 shown in FIG. 15 can also be executed by the network node 150. In step 1502, the network node 150 provides timing information for the silent period to at least one of the source node 110 and the receiver node 130. The provided information may include when the silent period starts and ends, a schedule for providing the silent period and / or information on pre- and post-patterns.

[0183] The network node 150 may provide this information through various means, such as sending a message to the source node 110 or receiver node 130. When the network node 150 provides the timing information, it enables the source node 110 to obtain this information and provide it to the BSC device, as described in step 1102 of the source node method 1100. The BSC device can then initiate the silent period at the correct time based on the provided timing information, as described in Step 808 of the BSC device method 800.

[0184] The receiver node may also receive the timing information and estimate interference caused by the electromagnetic carrier signals during the silent period, as described in Step 710 of the receiver node method 700. The receiver node uses the timing information to accurately synchronize its operations with those of the BSC device 120.

[0185] The network nodes performing the methods described in FIGs. 13 to 15 may be implemented by separate devices or by a common device such as one or more devices 150, e.g. one or more gNB(s). Furthermore, the device(s) implementing the network node(s) may also implement one or more of the above-described source node methods.

[0186] Summarizing, at least the following EXAMPLES have been disclosed:

[0187] EXAMPLE 1 : A method for a receiver node configured to receive information from a backscatter communication device, wherein the backscatter communication device (120) is configured to transmit information by modulating electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (700) comprises: determining (708) an initiation for a silent period (424) of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device (120), and receiving (712) information from the backscatter communication device (120), based on the determined initiation, wherein the determined initiation enables the receiver device (130) to estimate (710) interference of the electromagnetic carrier signals based on an analysis of the silent period (424), and to perform an interference cancelling (714) in the electromagnetic carrier signals based on the estimated interference.

[0188] EXAMPLE 2: The method of EXAMPLE 1 , further comprising: performing the interference cancelling (714) in the electromagnetic carrier signals based on the estimated interference.

[0189] EXAMPLE 3: The method of EXAMPLE 1 or EXAMPLE 2, wherein the initiation causes generation of a pre-pattern (422) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the pre-pattern (422) precedes and announces a beginning of the silent period (424). EXAMPLE 4: The method of any one of the preceding EXAMPLES, wherein the initiation causes generation of a post-pattern (426) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the post-pattern (426) follows and announces an end of the silent period (424).

[0190] EXAMPLE 5: The method of EXAMPLE 3 and EXAMPLE 4, further comprising: obtaining (702) at least one property of at least one of the pre-pattern (422), the postpattern (426) and the silent period (424) from at least one of: a source node (110) of the electromagnetic carrier signals, based on an identifier of the backscatter communication device (120), a network configuration of a communications network in which the backscatter communication device (120), the receiver node (130) and the source node (110) reside.

[0191] EXAMPLE 6: The method of any one of the preceding EXAMPLES, wherein the duration of the silent period (424) is a number of symbol durations of modulation symbols of a modulation of the information that fit in within ten percent of the shortest expected channel coherence time.

[0192] EXAMPLE 7: The method of any one of the preceding EXAMPLES, wherein the silent period (424), optionally including pre- and post-patterns (422, 426), precedes and announces a transmission of a block of information (428) transmitted by the backscatter communication device (120), and / or follows a transmission of a block of information (428) transmitted by the backscatter communication device (120).

[0193] EXAMPLE 8: The method of any one of the preceding EXAMPLES, wherein the silent period (424), optionally including pre- and post-patterns (422, 426), is inserted in a transmission of a block (428) of information transmitted by the backscatter communication device (120).

[0194] EXAMPLE 9: The method of any one of the preceding EXAMPLES, further comprising: receiving (704) a request (604) instructing the backscatter communication device (120) to transmit information, and determining the initiation based on the request (604).

[0195] EXAMPLE 10: The method of EXAMPLE 9, wherein the request (604) includes characteristics of the electromagnetic carrier signals.

[0196] EXAMPLE 11 : The method of any one of the preceding EXAMPLES, further comprising: obtaining (706) a timing of the silent period, the timing being indicative of executing the silent period (424) by the backscatter communication device (120), and determining (708) the initiation based on the timing.

[0197] EXAMPLE 12: The method of any one of the preceding EXAMPLES, wherein the electromagnetic carrier signals (142) incident on the backscatter communication device (120) are transmitted from a source node (110), wherein the interference includes electromagnetic carrier signals (160) from the source node (110) received at the receiver node (130) via a path other than a path via the backscatter communication device (120).

[0198] EXAMPLE 13: The method of any one of the preceding EXAMPLES, further comprising: receiving (704) a request indicative of the initiation from a communications network (100) in which the backscatter communication device (120), the receiver node (130) and a source node (110) reside.

[0199] EXAMPLE 14: A method for use in a backscatter communication device configured to transmit information, to a receiver node (130), by modulating electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (800) comprises: determining (808) an initiation for a silent period (424) of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device (120), executing (810) the silent period (424) in accordance with the initiation, thereby enabling the receiver node (130) to estimate interference caused by the electromagnetic carrier signals.

[0200] EXAMPLE 15: The method of EXAMPLE 14, wherein the initiation causes generation of a pre-pattern (422) of one or more on-periods during which the incident electromagnetic carrier signals are reflected by the backscatter communication device (120) and / or one or more off- periods during which the incident electromagnetic carrier signals are absorbed by the backscatter communication device (120), wherein the pre-pattern (422) precedes and / or announces a beginning of the silent period (424).

[0201] EXAMPLE 16: The method of EXAMPLE 14 or EXAMPLE 15, wherein the initiation causes generation of a post-pattern (426) of one or more on-periods during which the incident electromagnetic carrier signals are reflected by the backscatter communication device (120) and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed by the backscatter communication device (120), wherein the post-pattern (426) follows and / or announces an end of the silent period (424).

[0202] EXAMPLE 17: The method of EXAMPLE 15 and EXAMPLE 16, further comprising: obtaining (802) at least one property of at least one of the pre-pattern (422), the postpattern (426) and the silent period (424) from at least one of: a source node (110) of the electromagnetic carrier signals, based on an identifier of the backscatter communication device (120), a network configuration of a communications network (100) in which the backscatter communication device (120), the receiver node (130) and the source node (110) reside.

[0203] EXAMPLE 18: The method of any one of the preceding EXAMPLES 14 to 17, wherein the duration of the silent period (424) is up to a number of symbol durations of modulation symbols of a modulation of the information that fit in within ten percent of the shortest expected channel coherence time.

[0204] EXAMPLE 19: The method of any one of the preceding EXAMPLES 14 to 18, wherein the silent period (424), optionally including pre- and post-patterns (422, 426), precedes and announces a transmission of a block of data (428) transmitted by the backscatter communication device (120). EXAMPLE 20: The method of any one of the preceding EXAMPLES 14 to 19, wherein the silent period (424), optionally including pre- and post-patterns (422, 426), follows a transmission of a block of data (428) transmitted by the backscatter communication device (120).

[0205] EXAMPLE 21 : The method of any one of the preceding EXAMPLES 14 to 20, wherein the silent period (424), optionally including pre- and post-patterns (422, 426), is inserted in a transmission of a block of data (428) transmitted by the backscatter communication device (120).

[0206] EXAMPLE 22: The method of any one of the preceding EXAMPLES 14 to 21 , wherein the backscatter communication device (120) harvests energy by absorbing the incident electromagnetic carrier signals during the silent period (424).

[0207] EXAMPLE 23: The method of any one of the preceding EXAMPLES 14 to 22, further comprising: receiving (804) a request (606) to transmit information, and determining the initiation based on the request (606).

[0208] EXAMPLE 24: The method of EXAMPLE 23, wherein the request (606) includes characteristics of the electromagnetic carrier signals.

[0209] EXAMPLE 25: The method of any one of the preceding EXAMPLES 14 to 24, further comprising: obtaining (806) a timing for providing the silent period (424), wherein the initiation for the silent period (424) is determined based on the timing.

[0210] EXAMPLE 26: The method of any one of the preceding EXAMPLES 14 to 25, wherein the electromagnetic carrier signals incident on the backscatter communication device (120) are transmitted from a source node (110), wherein the interference includes electromagnetic carrier signals (160) from the source node (110) received at the receiver node (110) via a path other than a path via the backscatter communication device (120).

[0211] EXAMPLE 27: A method for a source node for providing electromagnetic carrier signals for a backscatter communication device (120) configured to transmit information, to a receiver node (130), by modulating the electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (900) comprises: providing (904) for the backscatter communication device (120) at least one property of at least one of a pre-pattern (422), a post-pattern (4426) and a silent period (424), wherein the backscatter communication device (120) executes the silent period (424) of a predefined duration in accordance with an initiation, wherein during the silent period (424) the electromagnetic carrier signals are absorbed at the backscatter communication device (120), thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals, wherein the initiation causes generation of at least one of the pre-pattern (422) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device (120) and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device (120), wherein the pre-pattern (422) precedes and announces a beginning of the silent period (424), and the post-pattern (426) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device (120) and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device (120), wherein the post-pattern (426) follows and announces an end of the silent period (424).

[0212] EXAMPLE 28: The method EXAMPLE 27, further comprising: obtaining (902) the at least one property of the at least one of the pre-pattern (422), the post-pattern (426) and the silent period (424) from a communications network (100) in which the backscatter communication device (120), a receiver node (130) receiving the information from the backscatter communication device (120), and the source node (110) reside.

[0213] EXAMPLE 29: A method for a source node for providing electromagnetic carrier signals for a backscatter communication device (120) configured to transmit information, to a receiver node (130), by modulating the electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (1000) comprises: providing (1002) for the backscatter communication device (120) a request (606) to transmit information, wherein the backscatter communication device (120) executes a silent period (424) in accordance with an initiation, wherein during the silent period (424) the electromagnetic carrier signals are absorbed at the backscatter communication device (120), thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals, wherein the initiation is determined based on the request (606).

[0214] EXAMPLE 30: The method of EXAMPLE 29, wherein the request (606) includes characteristics of the electromagnetic carrier signals.

[0215] EXAMPLE 31 : A method for a source node for providing electromagnetic carrier signals for a backscatter communication device (120) configured to transmit information, to a receiver node (130), by modulating the electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (1100) comprises: providing (1102) for the backscatter communication device (120) a timing for providing a silent period (424), wherein the backscatter communication device (120) executes the silent period (424) in accordance with an initiation, wherein the silent period (424) is of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device (120) are absorbed, thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals, wherein the initiation is determined based on the timing.

[0216] EXAMPLE 32: A method for a source node for providing electromagnetic carrier signals for a backscatter communication device (120) configured to transmit information, to a receiver node (130), by modulating the incident electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the method (1200) comprises: providing (1204) for the backscatter communication device (120) an initiation for executing a silent period (424) of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device (120) are absorbed, thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals.

[0217] EXAMPLE 33: The method of EXAMPLE 32, further comprising: receiving (1202) a request indicative of the initiation from a communications network (100) in which the backscatter communication device (120), the receiver node (130) receiving the information from the backscatter communication device (120), and the source node (110) reside.

[0218] EXAMPLE 34: A method for a network node of a communications network in which a backscatter communication device (120), a receiver node (130) receiving information from the backscatter communication device (120), and a source node (110) reside, wherein the backscatter communication device (120) is configured to transmit the information by modulating electromagnetic carrier signals from the source node (110) that are incident at the backscatter communication device (120), wherein the method (1300) comprises: providing (1302) an initiation to at least one of the source node (110) and the receiver node (130), wherein the initiation is indicative that the backscatter communication device (120) executes a silent period (424) in accordance with the initiation, wherein the silent period (424) is of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device (120) are absorbed, thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals.

[0219] EXAMPLE 35: A method for a network node of a communications network in which a backscatter communication device (120), a receiver node (130) receiving information from the backscatter communication device (120), and a source node (110) reside, wherein the backscatter communication device (120) is configured to transmit the information by modulating electromagnetic carrier signals from the source node (110) that are incident at the backscatter communication device (120), wherein the method (1400) comprises: providing (1402) at least one property of at least one of a pre-pattern (422), a post-pattern (426) and a silent period (424) to at least one of the source node (110) and the receiver node (130), wherein the backscatter communication device (120) executes the silent period (424) of a predefined duration in accordance with an initiation, wherein during the silent period (424) the electromagnetic carrier signals are absorbed at the backscatter communication device (120), thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals, wherein the initiation causes generation of at least one of the pre-pattern (422) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device (120) and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device (120), wherein the pre-pattern (422) precedes and announces a beginning of the silent period (424), and the post-pattern (426) of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device (120) and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device (120), wherein the post-pattern (426) follows and announces an end of the silent period (424).

[0220] EXAMPLE 36: A method for a network node of a communications network in which a backscatter communication device (120), a receiver node (130) receiving information from the backscatter communication device (120), and a source node (110) reside, wherein the backscatter communication device (120) is configured to transmit the information by modulating electromagnetic carrier signals from the source node (110) that are incident at the backscatter communication device (120), wherein the method (1500) comprises: providing (1502) a timing to at least one of the source node (110) and the receiver node (130), wherein the backscatter communication device (120) executes a silent period (424) of a predefined duration in accordance with the timing, wherein during the silent period (424) the electromagnetic carrier signals are absorbed at the backscatter communication device (120), thereby enabling the receiver node (130) to estimate interference of the electromagnetic carrier signals.

[0221] EXAMPLE 37: A device of a communication system, the device (130) comprising a control circuitry (132) for implementing a receiving node (130) configured to receive information from a backscatter communication device (120), wherein the backscatter communication device (120) is configured to transmit information by modulating electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the control circuitry (132) is configured to: determine (708) an initiation for a silent period (424) of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device (120), and receive (712) information from the backscatter communication device (120), based on the determined initiation, wherein the determined initiation enables the device (130) to estimate (710) interference of the electromagnetic carrier signals based on an analysis of the silent period (424), and to perform an interference cancelling (714) in the electromagnetic carrier signals based on the estimated interference.

[0222] EXAMPLE 38: The device of EXAMPLE 37, wherein the control circuitry (132) is configured to perform the method of any one of EXAMPLES 1 to 13.

[0223] EXAMPLE 39: A backscatter communication device comprising a control circuitry (122) for implementing a backscatter communication configured to transmit information, to a receiver node (130), by modulating electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the control circuitry (122) is configured to: determine (808) an initiation for a silent period (424) of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device (120), execute (810) the silent period (424) in accordance with the initiation, thereby enabling the receiver node (130) to estimate interference caused by the electromagnetic carrier signals.

[0224] EXAMPLE 40. The backscatter communication device of EXAMPLE 39, wherein the control circuitry (122) is configured to perform the method of any one of EXAMPLES 14 to 26.

[0225] EXAMPLE 41 : A device of a communication system, the device (110) comprising a control circuitry (112) for implementing a source node (110) for providing electromagnetic carrier signals for a backscatter communication device (120) configured to transmit information, to a receiver node (130), by modulating the electromagnetic carrier signals that are incident at the backscatter communication device (120), wherein the control circuitry (112) is configured to perform the method of any one of EXAMPLES 27 to 33.

[0226] EXAMPLE 42: A device of a communication system, the device (150) comprising a control circuitry (152) for implementing a network node (150) of a communications network (100) in which a backscatter communication device (120), a receiver node (130) receiving information from the backscatter communication device (120), and a source node reside (110), wherein the backscatter communication device (120) is configured to transmit the information by modulating electromagnetic carrier signals from the source node (110) that are incident at the backscatter communication device (120), wherein the control circuitry (152) is configured to perform the method of any one of EXAMPLES 34 to 36.

[0227] EXAMPLE 43: A system, comprising the device (130) of EXAMPLE 37 and the device (120) of EXAMPLE 39.

Claims

CLAIMS1. A method for a receiver node configured to receive information from a backscatter communication device, wherein the backscatter communication device is configured to transmit information by modulating electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: determining an initiation for a silent period of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device, and receiving information from the backscatter communication device, based on the determined initiation, wherein the determined initiation enables the receiver device to estimate interference of the electromagnetic carrier signals based on an analysis of the silent period, and to perform an interference cancelling in the electromagnetic carrier signals based on the estimated interference.

2. The method of claim 1 , further comprising: performing the interference cancelling in the electromagnetic carrier signals based on the estimated interference.

3. The method of claim 1, wherein the initiation causes generation of a pre-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the pre-pattern precedes and announces a beginning of the silent period.

4. The method of claim 1 , wherein the initiation causes generation of a post-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the post-pattern follows and announces an end of the silent period.

5. The method of claim 4, further comprising: obtaining at least one property of at least one of the pre-pattern, the post-pattern and the silent period from at least one of: a source node of the electromagnetic carrier signals, based on an identifier of the backscatter communication device, a network configuration of a communications network in which the backscatter communication device, the receiver node and the source node reside.

6. The method of claim 1 , wherein the duration of the silent period is a number of symbol durations of modulation symbols of a modulation of the information that fit in within ten percent of the shortest expected channel coherence time.

7. The method of claim 1 , further comprising: receiving a request instructing the backscatter communication device to transmit information, and determining the initiation based on the request.

8. The method of claim 1 , further comprising:obtaining a timing of the silent period, the timing being indicative of executing the silent period by the backscatter communication device, and determining the initiation based on the timing.

9. The method of claim 1 , wherein the electromagnetic carrier signals incident on the backscatter communication device are transmitted from a source node, wherein the interference includes electromagnetic carrier signals from the source node received at the receiver node via a path other than a path via the backscatter communication device.

10. The method of claim 1 , further comprising: receiving a request indicative of the initiation from a communications network in which the backscatter communication device, the receiver node and a source node reside.

11. A method for use in a backscatter communication device configured to transmit information, to a receiver node, by modulating electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: determining an initiation for a silent period of a predefined duration during which the electromagnetic carrier signals are absorbed at the backscatter communication device, executing the silent period in accordance with the initiation, thereby enabling the receiver node to estimate interference caused by the electromagnetic carrier signals.

12. The method of claim 11 , further comprising: receiving a request to transmit information, and determining the initiation based on the request.

13. The method of claim 12, wherein the request includes characteristics of the electromagnetic carrier signals.

14. A method for a source node for providing electromagnetic carrier signals for a backscatter communication device configured to transmit information, to a receiver node, by modulating the electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: providing for the backscatter communication device at least one property of at least one of a pre-pattern, a post-pattern and a silent period, wherein the backscatter communication device executes the silent period of a predefined duration in accordance with an initiation, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals, wherein the initiation causes generation of at least one of the pre-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the pre-pattern precedes and announces a beginning of the silent period, andthe post-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the post-pattern follows and announces an end of the silent period.

15. A method for a source node for providing electromagnetic carrier signals for a backscatter communication device configured to transmit information, to a receiver node, by modulating the electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: providing for the backscatter communication device a request to transmit information, wherein the backscatter communication device executes a silent period in accordance with an initiation, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals, wherein the initiation is determined based on the request.

16. A method for a source node for providing electromagnetic carrier signals for a backscatter communication device configured to transmit information, to a receiver node, by modulating the electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: providing for the backscatter communication device a timing for providing a silent period, wherein the backscatter communication device executes the silent period in accordance with an initiation, wherein the silent period is of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals, wherein the initiation is determined based on the timing.

17. A method for a source node for providing electromagnetic carrier signals for a backscatter communication device configured to transmit information, to a receiver node, by modulating the incident electromagnetic carrier signals that are incident at the backscatter communication device, wherein the method comprises: providing for the backscatter communication device an initiation for executing a silent period of a predefined duration during which the electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals.

18. A method for a network node of a communications network in which a backscatter communication device, a receiver node receiving information from the backscatter communication device, and a source node reside, wherein the backscatter communication device is configured to transmit the information by modulating electromagnetic carrier signals from the source node that are incident at the backscatter communication device, wherein the method comprises: providing an initiation to at least one of the source node and the receiver node, wherein the initiation is indicative that the backscatter communication device executes a silent period in accordance with the initiation, wherein the silent period is of a predefined duration during whichthe electromagnetic carrier signals incident on the backscatter communication device are absorbed, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals.

19. A method for a network node of a communications network in which a backscatter communication device, a receiver node receiving information from the backscatter communication device, and a source node reside, wherein the backscatter communication device is configured to transmit the information by modulating electromagnetic carrier signals from the source node that are incident at the backscatter communication device, wherein the method comprises: providing at least one property of at least one of a pre-pattern, a post-pattern and a silent period to at least one of the source node and the receiver node, wherein the backscatter communication device executes the silent period of a predefined duration in accordance with an initiation, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals, wherein the initiation causes generation of at least one of the pre-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the pre-pattern precedes and announces a beginning of the silent period, and the post-pattern of one or more on-periods during which the incident electromagnetic carrier signals are reflected at the backscatter communication device and / or one or more off-periods during which the incident electromagnetic carrier signals are absorbed at the backscatter communication device, wherein the post-pattern follows and announces an end of the silent period.

20. A method for a network node of a communications network in which a backscatter communication device, a receiver node receiving information from the backscatter communication device, and a source node reside, wherein the backscatter communication device is configured to transmit the information by modulating electromagnetic carrier signals from the source node that are incident at the backscatter communication device, wherein the method comprises: providing a timing to at least one of the source node and the receiver node, wherein the backscatter communication device executes a silent period of a predefined duration in accordance with the timing, wherein during the silent period the electromagnetic carrier signals are absorbed at the backscatter communication device, thereby enabling the receiver node to estimate interference of the electromagnetic carrier signals.

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