Techniques for interference reduction between passive wireless devices

Abstract

This disclosure provides systems, methods, and apparatus, including computer programs encoded on a computer storage medium, for interference reduction techniques between passive wireless devices. In some aspects, a source device, a reader device, or a passive wireless device may support one or more interference avoidance mechanisms, according to which the reader device may experience less interference from other devices within the system, such that the reader device may experience less interference from the other devices within the system. Messages for the reader device may be decoded more accurately based on radio frequency signaling received at an antenna of the reader device, or both. In some implementations, a plurality of passive wireless devices may each add or apply a respective communication signature to a reflected or backscattered signal from the passive wireless device. The respective communication signature may uniquely identify backscatter signaling from a particular passive wireless device such that the reader device may parse the received signaling and extract and decode related messages.

Description

[0001] The present disclosure relates to wireless communications, including interference reduction techniques between passive wireless devices. Background Art

[0002] Wireless communication systems are widely deployed to provide various types of communication content, such as voice, video, packet data, messaging, broadcasting, etc. These systems may be able to support communication with multiple users by sharing available system resources (such as time, frequency and power). Examples of such multiple access systems include fourth generation (4G) systems (such as long term evolution (LTE) systems, advanced LTE (LTE-A) systems or LTE-A Pro systems) and fifth generation (5G) systems (which may be referred to as new radio (NR) systems). These systems may use techniques such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA) or discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM). A wireless multiple access communication system may include one or more base stations (BS) or one or more network access nodes, each base station or network access node simultaneously supporting communication for multiple communication devices, which may be further referred to as user equipment (UE). Summary of the invention

[0003] The systems, methods and devices of the present disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0004] One innovative aspect of the subject matter described in the present disclosure can be implemented in a method for wireless communication at a passive wireless device. The method may include: receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscattered communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscattered communication; receiving a first message from the source device; and sending a second message to the reader device via backscatter of the first message and based on the communication signature.

[0005] Another innovative aspect of the subject matter described in the present disclosure may be implemented in an apparatus for wireless communication at a passive wireless device. The apparatus may include: one or more interfaces; and a processing system. The one or more interfaces may be configured to: obtain an indication of a communication signature in a communication signature set, the communication signature being specific to backscattered communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscattered communication; obtain a first message from the source device; and output a second message to the reader device via backscatter of the first message and based on the communication signature.

[0006] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication at a passive wireless device. The apparatus may include: a processor; a memory coupled to the processor; and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: receive an indication of a communication signature in a communication signature set, the communication signature being specific to backscattered communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscattered communication; receive a first message from the source device; and send a second message to the reader device via backscatter of the first message and based on the communication signature.

[0007] Another innovative aspect of the subject matter described in the present disclosure can be implemented in another apparatus for wireless communication at a passive wireless device. The apparatus may include: a component for receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; a component for receiving a first message from the source device; and a component for sending a second message to the reader device via backscatter of the first message and based on the communication signature.

[0008] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium storing code for wireless communication at a passive wireless device. The code may include instructions executable by a processor to: receive an indication of a communication signature in a communication signature set, the communication signature being specific to backscattered communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscattered communication; receive a first message from the source device; and send a second message to the reader device via backscatter of the first message and based on the communication signature.

[0009] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a method for wireless communication at a reader device. The method can include: receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and receiving a message via backscatter from the passive wireless device in accordance with the communication signature.

[0010] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication at a reader device. The apparatus may include: an interface; and a processing system. The one or more interfaces may be configured to: obtain an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and obtain a message via backscatter from the passive wireless device based on the communication signature.

[0011] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication at a reader device. The apparatus may include: a processor; a memory coupled to the processor; and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: receive an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and receive a message via backscatter from the passive wireless device according to the communication signature.

[0012] Another innovative aspect of the subject matter described in the present disclosure can be implemented in another apparatus for wireless communication at a reader device. The apparatus may include: means for receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and means for receiving a message via backscatter from the passive wireless device in accordance with the communication signature.

[0013] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium storing code for wireless communication at a reader device. The code can include instructions executable by a processor to: receive an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and receive a message via backscatter from the passive wireless device in accordance with the communication signature.

[0014] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a method for wireless communication at a source device. The method can include: sending an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and sending a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0015] Another innovative aspect of the subject matter described in the present disclosure may be implemented in an apparatus for wireless communication at a source device. The apparatus may include: one or more interfaces; and a processing system. The one or more interfaces may be configured to: output an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and output a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0016] Another innovative aspect of the subject matter described in the present disclosure can be implemented in an apparatus for wireless communication at a source device. The apparatus may include: a processor; a memory coupled to the processor; and instructions stored in the memory. The instructions may be executable by the processor to cause the apparatus to: send an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and send a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0017] Another innovative aspect of the subject matter described in the present disclosure can be implemented in another apparatus for wireless communication at a source device. The apparatus may include: means for sending an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and means for sending a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0018] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a non-transitory computer-readable medium storing code for wireless communication at a source device. The code can include instructions executable by a processor to: send an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and send a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0019] The details of one or more specific implementations of the subject matter described in the present disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. It should be noted that the relative dimensions in the drawings may not be drawn to scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 An example wireless communication system that supports interference reduction techniques between passive wireless devices is shown.

[0021] Figure 2 An example network architecture that supports interference reduction techniques between passive wireless devices is shown.

[0022] Figure 3 An example signaling diagram is shown to support interference reduction techniques between passive wireless devices.

[0023] Figure 4 Example code-based communication signatures that support interference reduction techniques between passive wireless devices are shown.

[0024] Figure 5 Example frequency domain responses for backscatter communications supporting interference reduction techniques between passive wireless devices are shown.

[0025] Figure 6 An example process flow is shown that supports interference reduction techniques between passive wireless devices.

[0026] Figure 7 and Figure 8 A block diagram of an example device that supports interference reduction techniques between passive wireless devices is shown.

[0027] Figures 9 to 11 A flow chart illustrating a method of supporting interference reduction techniques between passive wireless devices is shown.

[0028] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

[0029] For the purpose of describing the innovative aspects of the present disclosure, the following description refers to some specific implementations. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The described specific implementations can be implemented in any device, system, or network capable of sending and receiving radio frequency (RF) signals in accordance with any one of the Institute of Electrical and Electronics Engineers (IEEE) 16.11 standards or any one of the following: IEEE 802.11 standards, Standard, Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Global System for Mobile Communications (GSM), GSM or General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution-Data Optimized (EV-DO), 1xEV-DO, EV-DO Rev A, EV-DO Rev B, High Speed ​​Packet Access (HSPA), High Speed ​​Downlink Packet Access (HSDPA), High Speed ​​Uplink Packet Access (HSUPA), Evolved High Speed ​​Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals for communicating within a wireless, cellular or Internet of Things (IOT) network, such as a system utilizing third generation (3G) technology, fourth generation (4G) technology, fifth generation (5G) or sixth generation (6G) technology, or another specific implementation thereof.

[0030] In some wireless communication systems, a source device may send signaling to a reader device via a passive wireless device, which may be referred to or understood as a reflection device or backscatter device. A wireless tag in an Internet of Things (IoT) deployment may be an example of such a passive wireless device. A passive wireless device may modulate information about signaling received from a source device so that a reader device receives information from both the source device and the passive wireless device. For example, a passive wireless device may modulate information using signaling from a source device according to turning on reflection to send or transmit a first bit (such as a bit "1") and according to turning off reflection to send or transmit a second bit (such as a bit "0"). In some systems, source devices, reader devices, or passive wireless devices may be densely deployed and may experience relatively high levels of interference. For example, backscatter communications between different source devices and reader device pairs using the same subchannel or nearby subchannels may interfere with each other because some reflected signaling may leak across subchannels. Due to such interference, the likelihood of successful decoding by a reader device may be reduced.

[0031] In some implementations, a source device, a reader device, or a passive wireless device may support one or more configuration-based or signaling-based interference avoidance mechanisms, according to which the reader device may experience less interference from other devices within the system, or may more accurately decode related messaging based on radio frequency signaling received at the antenna of the reader device, or both. For example, in some deployments, each passive wireless device in the system may add or otherwise apply a corresponding communication signature to a reflected signal or backscattered signal from the passive wireless device, wherein such communication signature may include a time domain code sequence or a power scaling factor that uniquely identifies which passive wireless device backscattered the associated signaling. Additionally or alternatively, the source device may send an indication of a bandwidth over which the passive wireless device is to backscatter signaling, and the passive wireless device may filter out any radio frequency energy received outside the indicated bandwidth. Additionally or alternatively, the source device and the reader device may support a power control configuration, according to which the source device uses a specific transmit power for backscatter communication if another device is simultaneously using the same subchannel. Further, the source device and the reader device may support a mapping relationship between which subchannels are occupied and which subchannels are available (such that inputting the occupied subchannels into the mapping relationship will output an indication of which subchannels can be used). Therefore, the reader device can decode according to the use indication or expected time domain code sequence, perform continuous cancellation associated with the indicated or expected power scaling factor, or receive backscatter communications using a subchannel in the set of available subchannels, thereby extracting signaling related to or for the reader.

[0032] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. For example, a reader device may have a higher probability of successful decoding due to support for interference avoidance in a deployment associated with backscatter communications from one or more passive wireless devices based on a backscatter-specific communication signature or a backscatter-specific subchannel selection procedure. Based on such a higher probability of successful decoding, the source device and the reader device may achieve a higher reliability of backscatter communications, which may improve system performance (such as increasing data rates, user experience, and system capacity). Further, due to such higher reliability and system performance, the described technology may facilitate a wider adoption of passive wireless devices, which may increase data rates and system capacity on various networks. For example, a system involving reliable passive wireless devices may provide relatively higher data rates, greater capacity, or otherwise perform enhanced operations compared to a system without reliable passive wireless devices.

[0033] Figure 1An example wireless communication system 100 supporting interference reduction techniques between passive wireless devices is shown. The wireless communication system 100 may include one or more network entities 105, one or more UEs 115, and a core network 130. In some implementations, the wireless communication system 100 may be a Long Term Evolution (LTE) network, an Advanced LTE (LTE-A) network, an LTE-A Pro network, a New Radio (NR) network, or a network operating according to other systems and radio technologies (including future systems and radio technologies not explicitly mentioned herein).

[0034] The network entities 105 may be dispersed throughout a geographic area to form the wireless communication system 100 and may include devices in different forms or with different capabilities. In various examples, the network entities 105 may be referred to as network elements, mobility elements, radio access network (RAN) nodes, or network equipment, among other nomenclature. In some implementations, the network entities 105 and the UE 115 may communicate wirelessly via one or more communication links 125, such as radio frequency (RF) access links. For example, the network entity 105 may support a coverage area 110, such as a geographic coverage area, over which the UE 115 and the network entity 105 may establish one or more communication links 125. The coverage area 110 may be an example of a geographic area within which the network entity 105 and the UE 115 may support signal communications according to one or more radio access technologies (RATs).

[0035] The UEs 115 may be dispersed throughout the coverage area 110 of the wireless communication system 100, and each UE 115 may be stationary or mobile or stationary and mobile at different times. The UEs 115 may be devices in different forms or with different capabilities. Figure 1 Some example UEs 115 are illustrated in FIG. 1. The UEs 115 described herein may be capable of supporting communication with various types of devices, such as Figure 1 Communicate with other UEs 115 or network entities 105) as shown.

[0036] As described herein, a node of the wireless communication system 100 (which may be referred to as a network node or a wireless node) may be a network entity 105 (such as any network entity described herein), a UE 115 (such as any UE described herein), a network controller, an apparatus, a device, a computing system, one or more components, or another suitable processing entity configured to perform any of the techniques described herein. For example, the node may be a UE 115. As another example, the node may be a network entity 105. As another example, a first node may be configured to communicate with a second node or a third node. In one aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a UE 115. In another aspect of this example, the first node may be a UE 115, the second node may be a network entity 105, and the third node may be a network entity 105. In other aspects of this example, the first node, the second node, and the third node may be different relative to these examples. Similarly, references to UE 115, network entity 105, apparatus, device, computing system, etc. may include disclosure of UE 115, network entity 105, apparatus, device, computing system, etc. as nodes. For example, a disclosure that UE 115 is configured to receive information from network entity 105 also discloses that the first node is configured to receive information from a second node.

[0037] In some implementations, the network entities 105 may communicate with the core network 130, or with each other, or both. For example, the network entities 105 may communicate with the core network 130 via one or more backhaul communication links 120 (such as according to S1, N2, N3, or other interface protocols). In some implementations, the network entities 105 may communicate with each other via the backhaul communication links 120 (such as according to X2, Xn, or other interface protocols) directly (such as directly between the network entities 105) or indirectly (such as via the core network 130). In some implementations, the network entities 105 may communicate with each other via the midhaul communication links 162 (such as according to the midhaul interface protocol) or the fronthaul communication links 168 (such as according to the fronthaul interface protocol), or any combination thereof. The backhaul communication links 120, the midhaul communication links 162, or the fronthaul communication links 168 may be or include one or more wired links (such as electrical links, optical fiber links), one or more wireless links (such as radio links, wireless optical links), etc., or various combinations thereof. UE 115 may communicate with core network 130 via communication link 155 .

[0038] One or more of the network entities 105 described herein may include or may be referred to as a base station (BS) 140 (such as a transceiver base station, a radio BS, an NR BS, an access point, a radio transceiver, a Node B, an evolved Node B (eNB), a next generation Node B, or a giga Node B (any of which may be referred to as a gNB), a 5G NB, a next generation eNB (ng-eNB), a home Node B, a home evolved Node B, or other suitable terms). In some specific implementations, the network entity 105 (such as BS 140) may be implemented in an aggregated (such as a monolithic, standalone) BS architecture, which may be configured to utilize a protocol stack physically or logically integrated within a single network entity 105 (such as a single RAN node, such as BS 140).

[0039] In some implementations, the network entity 105 may be implemented in a disaggregated architecture, such as a disaggregated BS architecture, a disaggregated RAN architecture, which may be configured to utilize a protocol stack that is physically or logically distributed between two or more network entities 105, such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) such as a network configuration sponsored by the O-RAN Alliance, or a virtualized RAN (vRAN) such as a cloud RAN (C-RAN). For example, the network entity 105 may include one or more of the following: a central unit (CU) 160, a distributed unit (DU) 165, a radio unit (RU) 170, a RAN intelligent controller (RIC) 175 such as a near real-time RIC (near RT RIC), a non-real-time RIC (non-RT RIC), a service management and orchestration (SMO) 180 system, or any combination thereof. The RU 170 may also be referred to as a radio head, a smart radio head, a remote radio head (RRH), a remote radio unit (RRU), or a transmit receive point (TRP). One or more components of the network entity 105 in the decomposed RAN architecture may be co-located, or one or more components of the network entity 105 may be located in distributed locations (such as separate physical locations). In some implementations, one or more network entities 105 of the decomposed RAN architecture may be implemented as virtual units (such as virtual CU (VCU), virtual DU (VDU), virtual RU (VRU)).

[0040] The functional split between CU 160, DU 165, and RU 170 is flexible and may support different functionalities, depending on which functions (such as network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof) are performed at CU 160, DU 165, and RU 170. For example, a functional split of a protocol stack may be employed between CU 160 and DU 165, such that CU 160 may support one or more layers of a protocol stack, and DU 165 may support one or more different layers of a protocol stack. In some implementations, CU 160 may host higher protocol layer (such as layer 3 (L3), layer 2 (L2)) functionality and signaling (such as radio resource control (RRC), service data adaptation protocol (SDAP), packet data convergence protocol (PDCP)). The CU 160 may be connected to one or more DUs 165 or RUs 170, and the one or more DUs 165 or RUs 170 may host lower protocol layers, such as layer 1 (L1) (such as a physical (PHY) layer) or L2 (such as a radio link control (RLC) layer, a medium access control (MAC) layer) functionality and signaling, and may each be at least partially controlled by the CU 160. Additionally or alternatively, a functional split of the protocol stack may be employed between the DU 165 and the RU 170, such that the DU 165 may support one or more layers of the protocol stack, and the RU 170 may support one or more different layers of the protocol stack. The DU 165 may support one or more different cells (such as via one or more RUs 170). In some implementations, the functional split between the CU 160 and the DU 165 or between the DU 165 and the RU 170 may be within the protocol layer (such as some functions of the protocol layer may be performed by one of the CU 160, DU 165, or RU 170, while other functions of the protocol layer are performed by a different one of the CU 160, DU 165, or RU 170). The CU 160 may be further functionally split into CU control plane (CU-CP) and CU user plane (CU-UP) functions. The CU 160 may be connected to one or more DUs 165 via midhaul communication links 162 (such as F1, F1-c, F1-u), and the DU 165 may be connected to one or more RUs 170 via fronthaul communication links 168 (such as an open fronthaul (FH) interface). In some implementations, the midhaul communication link 162 or the fronthaul communication link 168 may be implemented based on an interface (such as a channel) between layers of a protocol stack supported by respective network entities 105 that communicate via such communication links.

[0041] In some wireless communication systems (such as wireless communication system 100), infrastructure and spectrum resources for radio access may support wireless backhaul link capabilities to supplement wired backhaul connections, thereby providing an IAB network architecture (such as to core network 130). In some specific implementations, in an IAB network, one or more network entities 105 (such as IAB nodes 104) may be partially controlled by each other. One or more IAB nodes 104 may be referred to as donor entities or IAB donors. One or more DUs 165 or one or more RUs 170 may be partially controlled by one or more CUs 160 associated with a donor network entity 105 (such as donor BS 140). One or more donor network entities 105 (such as IAB donors) may communicate with one or more additional network entities 105 (such as IAB nodes 104) via supported access and backhaul links (such as backhaul communication links 120). IAB nodes 104 may include IAB mobile terminations (IAB-MTs) controlled (such as scheduling) by DUs 165 of coupled IAB donors. The IAB-MT may include an independent set of antennas for relaying communications with the UE 115, or may share the same antennas of the IAB node 104 (such as RU 170) for access via the DU 165 of the IAB node 104 (such as referred to as a virtual IAB-MT (vIAB-MT)). In some implementations, the IAB node 104 may include a DU 165 that supports communication links with additional entities (such as IAB nodes 104, UE 115) within a relay chain or configuration (such as downstream) of the access network. In such implementations, one or more components of the decomposed RAN architecture (such as one or more IAB nodes 104 or components of the IAB node 104) may be configured to operate according to the techniques described herein.

[0042] In a specific implementation in which the techniques described herein are applied to the context of a decomposed RAN architecture, one or more components of the decomposed RAN architecture may be configured to support interference reduction techniques between passive wireless devices as described herein. For example, some operations described as being performed by UE 115 or network entity 105 (such as BS 140) may be additionally or alternatively performed by one or more components of the decomposed RAN architecture (such as IAB node 104, DU 165, CU 160, RU 170, RIC 175, SMO 180).

[0043] UE 115 may include or may be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a user device, or some other appropriate terminology, where a "device" may also be referred to as a unit, a station, a terminal, or a client, etc. UE 115 may also include or may be referred to as a personal electronic device, such as a cellular phone, a personal digital assistant (PDA), a tablet computer, a laptop computer, or a personal computer. In some specific implementations, UE 115 may include or may be referred to as a wireless local loop (WLL) station, an Internet of Things (IoT) device, an Internet of Everything (IoE) device, or a machine type communication (MTC) device, etc., which may be implemented in various objects such as appliances or vehicles, meters, etc.

[0044] like Figure 1 As shown, the UE 115 described herein may be able to communicate with various types of devices, such as other UEs 115, which may sometimes act as relays, as well as network entities 105 and network equipment, including macro eNBs or gNBs, small cell eNBs or gNBs, or relay BSs, etc.

[0045] The UE 115 and the network entity 105 may use resources associated with one or more carriers to communicate wirelessly with each other via one or more communication links 125 (such as access links). The term "carrier" may refer to a collection of RF spectrum resources having a physical layer structure defined to support the communication link 125. For example, a carrier for the communication link 125 may include a portion of an RF spectrum band (such as a bandwidth portion (BWP)) that operates according to one or more physical layer channels for a given radio access technology (such as LTE, LTE-A, LTE-APro, NR). Each physical layer channel may carry acquisition signaling (such as synchronization signals, system information), control signaling for coordinating carrier operations, user data, or other signaling. The wireless communication system 100 may support communications with the UE 115 using carrier aggregation or multi-carrier operation. Depending on the carrier aggregation configuration, the UE 115 may be configured to have multiple downlink component carriers and one or more uplink component carriers. Carrier aggregation may be used for both frequency division duplex (FDD) and time division duplex (TDD) component carriers. Communication between the network entity 105 and other devices may refer to communication between these devices and any part (such as an entity, a sub-entity) of the network entity 105. For example, the terms "send", "receive" or "communicate" when referring to the network entity 105 may refer to any part of the network entity 105 (such as BS 140, CU 160, DU 165, RU 170) of the RAN communicating with another device (such as directly or via one or more other network entities 105).

[0046] The signal waveform transmitted via the carrier wave may be composed of multiple subcarriers (such as using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)). In a system using MCM techniques, a resource element may refer to a symbol period (such as the duration of a modulation symbol) and a resource of a subcarrier, where the symbol period and the subcarrier spacing may be inversely related. The number of bits carried by each resource element may depend on the modulation scheme (such as the order of the modulation scheme, the coding rate of the modulation scheme, or both), so that a relatively higher number of resource elements (such as in the transmission duration) and a relatively higher order modulation scheme may correspond to a relatively higher communication rate. Wireless communication resources may refer to a combination of RF spectrum resources, time resources, and spatial resources (such as spatial layers or beams), and the use of multiple spatial resources may improve the data rate or data integrity of communications with UE 115.

[0047] The time interval for the network entity 105 or the UE 115 may be expressed as a multiple of a basic time unit. In some implementations, the basic time unit may refer to a sampling period T s =1 / (Δf max ·N f ) seconds, where Δf max It can represent the supported subcarrier spacing, and N f The supported discrete Fourier transform (DFT) size may be indicated. The time intervals of the communication resources may be organized according to radio frames each having a specific duration, such as 10 milliseconds (ms). Each radio frame may be identified by a system frame number (SFN), such as in the range of 0 to 1023.

[0048] Each frame may include multiple consecutively numbered subframes or time slots, and each subframe or time slot may have the same duration. In some specific implementations, the frame may be divided into subframes (such as in the time domain), and each subframe may be further divided into a certain number of time slots. Alternatively, each frame may include a variable number of time slots, and the number of time slots may depend on the subcarrier spacing. Each time slot may include a certain number of symbol periods (for example, this depends on the length of the cyclic prefix added in front of each symbol period). In some wireless communication systems 100, the time slot may be further divided into a plurality of mini-time slots associated with one or more symbols. Excluding the cyclic prefix, each symbol period may be associated with one or more (such as N) time slots. f The duration of a symbol period may depend on the subcarrier spacing or the operating frequency band.

[0049] A subframe, a time slot, a mini-time slot, or a symbol may be the smallest scheduling unit (such as in the time domain) of the wireless communication system 100, and may be referred to as a transmission time interval (TTI). In some implementations, the TTI duration (such as the number of symbol periods in a TTI) may be variable. Additionally or alternatively, the smallest scheduling unit of the wireless communication system 100 may be dynamically selected (such as in bursts of shortened TTIs (sTTIs)).

[0050] According to various techniques, physical channels may be multiplexed using carriers for communication. Physical control channels and physical data channels may be multiplexed for signaling via downlink carriers, for example, using one or more of a time division multiplexing (TDM) technique, a frequency division multiplexing (FDM) technique, or a hybrid TDM-FDM technique. A control region for a physical control channel, such as a control resource set (CORESET), may be defined by a set of symbol periods and may extend across a system bandwidth or a subset of a system bandwidth of a carrier. One or more control regions, such as CORESETs, may be configured for a set of UEs 115. For example, one or more UEs in UE115 may monitor or search a control region to obtain control information according to one or more search space sets, and each search space set may include one or more control channel candidates in one or more aggregation levels arranged in a cascaded manner. The aggregation level of a control channel candidate may refer to the number of control channel resources, such as control channel elements (CCEs), associated with coded information for a control information format having a given payload size. The search space sets may include a common search space set configured for transmitting control information to multiple UEs 115 , and a UE-specific search space set for transmitting control information to a specific UE 115 .

[0051] In some implementations, the network entities 105 (such as BS 140, RU 170) can be mobile and thus provide communication coverage for mobile coverage areas 110. In some implementations, different coverage areas 110 associated with different technologies can overlap, but different coverage areas 110 can be supported by the same network entity 105. In some other examples, overlapping coverage areas 110 associated with different technologies can be supported by different network entities 105. The wireless communication system 100 can include, for example, a heterogeneous network in which different types of network entities 105 use the same or different radio access technologies to provide coverage for various coverage areas 110.

[0052] Some UEs 115, such as MTC or IoT devices, may be low-cost or low-complexity devices and may provide automated communication between machines, such as via machine-to-machine (M2M) communication. M2M communication or MTC may refer to data communication technology that allows devices to communicate with each other or with a network entity 105, such as BS 140, without human intervention. In some implementations, M2M communication or MTC may include communication from devices that integrate sensors or meters to measure or capture information and relay such information to a central server or application that uses the information or presents the information to a person interacting with the application. Some UEs 115 may be designed to collect information or implement automated behavior of machines or other devices. Examples of applications for MTC devices include: smart metering, inventory monitoring, water level monitoring, equipment monitoring, health care monitoring, wildlife monitoring, weather and geographic event monitoring, queue management and tracking, remote security sensing, physical access control, and transaction-based commercial charging.

[0053] Some UEs 115 may be configured to employ a reduced power consumption mode of operation, such as half-duplex communication (such as a mode that supports unidirectional communication via transmission or reception but does not transmit and receive concurrently). In some implementations, half-duplex communication may be performed at a reduced peak rate. Other power saving techniques for UEs 115 include entering a power saving deep sleep mode when not engaged in active communications, operating using limited bandwidth (such as according to narrowband communications), or a combination of these techniques. For example, some UEs 115 may be configured to operate using a narrowband protocol type that is associated with a defined portion or range (e.g., a set of subcarriers or resource blocks (RBs)) within a carrier, within a guard band of a carrier, or outside a carrier.

[0054] The wireless communication system 100 may be configured to support ultra-reliable communication or low-latency communication or various combinations thereof. For example, the wireless communication system 100 may be configured to support ultra-reliable low-latency communication (URLLC). UE 115 may be designed to support ultra-reliable or low-latency or critical functions. Ultra-reliable communication may include private communication or group communication, and may be supported by one or more services (such as push-to-talk, video, or data). Support for ultra-reliable, low-latency functions may include prioritization of services, and such services may be used for public safety or general commercial applications. The terms "ultra-reliable", "low latency", and "ultra-reliable low latency" are used interchangeably herein.

[0055] In some implementations, a UE 115 may be configured to support communication directly with other UEs 115 via a device-to-device (D2D) communication link 135 (such as according to a peer-to-peer (P2P), D2D, or sidelink protocol). In some implementations, one or more UEs 115 in a group that are performing D2D communication may be within a coverage area 110 of a network entity 105 (such as a BS 140, RU 170), which may support aspects of such D2D communication configured (such as scheduling) by the network entity 105. In some implementations, one or more UEs 115 in such a group may be outside of the coverage area 110 of the network entity 105, or may otherwise be unable or not configured to receive transmissions from the network entity 105. In some implementations, a group of UEs 115 communicating via D2D communication may support a one-to-many (1:M) system, in which each UE 115 transmits to each other UE 115 in the group. In some implementations, the network entity 105 may facilitate scheduling of resources for D2D communications. In some other examples, D2D communications may be performed between UEs 115 without involving the network entity 105.

[0056] In some systems, the D2D communication link 135 may be an example of a communication channel (such as a sidelink communication channel) between vehicles (such as UE 115). In some implementations, the vehicles may communicate using vehicle-to-everything (V2X) communications, vehicle-to-vehicle (V2V) communications, or some combination of these. The vehicles may signal information related to traffic conditions, signal scheduling, weather, safety, emergency situations, or any other information related to the V2X system. In some implementations, the vehicles in the V2X system may communicate with roadside infrastructure (such as roadside units), or communicate with the network via one or more network nodes (such as network entity 105, base station 140, RU 170) using vehicle-to-network (V2N) communications, or both.

[0057] The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC) or a 5G core (5GC), which may include at least one control plane entity (such as a mobility management entity (MME), an access and mobility management function (AMF)) for managing access and mobility, and at least one user plane entity (such as a serving gateway (S-GW), a packet data network (PDN) gateway (P-GW), or a user plane function (UPF)) for routing packets or interconnecting to an external network. The control plane entity may manage non-access layer (NAS) functions, such as mobility, authentication, and bearer management of UE 115 served by a network entity 105 (such as BS 140) associated with the core network 130. User IP packets may be delivered through the user plane entity, which may provide IP address allocation and other functions. The user plane entity may be connected to the IP service 150 of one or more network operators. IP services 150 may include access to the Internet, an intranet, an IP Multimedia Subsystem (IMS), or packet-switched streaming services.

[0058] The wireless communication system 100 may operate using one or more frequency bands that may be in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally speaking, the region from 300 MHz to 3 GHz is referred to as the ultra-high frequency (UHF) region or decimeter band because the wavelength ranges from about one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features (which may be referred to as clusters), but these waves may be sufficient to penetrate structures so that macro cells provide services to UEs 115 located indoors. Communications using UHF waves may be associated with smaller antennas and shorter ranges (such as less than 100 kilometers) compared to communications using lower frequencies and longer waves in the high frequency (HF) or very high frequency (VHF) portions of the spectrum below 300 MHz.

[0059] The wireless communication system 100 may also operate in a super high frequency (SHF) region (also known as a centimeter band) in the range of 3 GHz to 30 GHz or in an extremely high frequency (EHF) region (such as 30 GHz to 300 GHz) (also known as a millimeter band) using a spectrum. In some specific implementations, the wireless communication system 100 may support millimeter wave (mmW) communication between UE 115 and network entity 105 (such as BS140, RU 170), and the EHF antenna of the corresponding device may be smaller and closer than the UHF antenna. In some specific implementations, such technology may facilitate the use of antenna arrays in the device. However, the propagation of EHF transmission may be affected by greater attenuation and shorter range than SHF or UHF transmission. The technology disclosed herein may be adopted across transmissions using one or more different frequency regions, and the use of frequency bands specified across these frequency regions may be different due to countries or regulatory agencies.

[0060] The wireless communication system 100 may utilize licensed and unlicensed RF spectrum bands. For example, the wireless communication system 100 may use unlicensed bands (such as the 5 GHz Industrial, Scientific, and Medical (ISM) band) to employ License Assisted Access (LAA), LTE Unlicensed (LTE-U) radio access technology, or NR technology. When operating using unlicensed RF spectrum bands, devices such as the network entity 105 and the UE 115 may employ carrier sensing for conflict detection and avoidance. In some specific implementations, operations using unlicensed bands may be based on a carrier aggregation configuration combined with component carriers operating using licensed bands (such as LAA). Operations using unlicensed spectrum may include downlink transmissions, uplink transmissions, P2P transmissions, or D2D transmissions, and the like.

[0061] The network entity 105 (such as BS140, RU 170) or UE 115 may be equipped with multiple antennas, which can be used to employ technologies such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communication or beamforming. The antennas of the network entity 105 or UE 115 may be located in one or more antenna arrays or antenna panels, which can support MIMO operations or transmit or receive beamforming. For example, one or more BS antennas or antenna arrays may be co-located at an antenna assembly (such as an antenna tower). In some specific implementations, the antennas or antenna arrays associated with the network entity 105 may be located at different geographical locations. The network entity 105 may include an antenna array having a collection of antenna ports of multiple rows and columns that the network entity 105 can use to support beamforming for communication with the UE 115. Similarly, the UE 115 may include one or more antenna arrays that can support various MIMO or beamforming operations. Additionally or alternatively, the antenna panel may support RF beamforming for signals sent via the antenna ports.

[0062] Beamforming (which may also be referred to as spatial filtering, directional transmission, or directional reception) is a signal processing technique that may be used at a transmitting device or a receiving device (such as a network entity 105, a UE 115) to shape or direct an antenna beam (such as a transmit beam, a receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining signals conveyed via antenna elements of an antenna array so that some signals propagating along a particular orientation relative to the antenna array experience constructive interference, while other signals experience destructive interference. Adjustments to signals conveyed via antenna elements may include the transmitting device or the receiving device applying an amplitude offset, a phase offset, or both to signals carried via antenna elements associated with the device. Adjustments associated with each antenna element may be defined by a set of beamforming weights associated with a particular orientation (such as relative to the antenna array of the transmitting device or the receiving device, or relative to some other orientation).

[0063] In some wireless communication systems (such as wireless communication system 100), various devices (such as any one or more UEs 115 or any one or more network entities 105 or any combination thereof) may communicate (such as transmit or receive or both) via one or more passive wireless devices, and may support one or more configuration-based or signaling-based mechanisms to avoid or mitigate interference between backscatter communications. For example, a source device and a reader device (each of the source device and the reader device may be an example of a UE 115 or a network entity 105) may communicate via a passive wireless device according to a passive wireless device that reflects communications from the source device to the reader device. Further, the passive wireless device may transmit additional information (such as information in addition to the information transmitted by the source device) to the reader device according to a backscatter modulation technique. As described herein, information or signaling transmitted by the source device may be referred to or understood as a first message, and information or signaling transmitted by the passive wireless device may be referred to or understood as a second message.

[0064] According to example implementations described herein, a passive wireless device (such as a tag in an IoT deployment) may add or apply a communication signature to the messaging backscattered by the passive wireless device from a source device to a reader device. In some implementations, the communication signature is specific to (such as unique to or dedicated to) the backscattered communications from the passive wireless device from the source device to the reader device. Therefore, if multiple passive wireless devices are deployed in a system, each passive wireless device may use a unique communication signature for the backscattered communications from the passive wireless device. The passive wireless device may receive an indication of the communication signature to be used (such as from one or both of the source device or the reader device), or the communication signature to be used may be stored in a memory of the passive wireless device, or both, and the corresponding reader device may receive an indication of the same communication signature, or store the same communication signature. Therefore, the reader device may accurately extract the relevant messaging based on the communication signature that is specific to or unique to the backscattered communications from a particular passive wireless device. Additionally or alternatively, the passive wireless device may support frequency domain filtering to focus backscatter communications from the passive wireless device to a specific frequency range (such as a specific subchannel), the source device and the reader device may employ a power control procedure specific to the scenario associated with backscatter communications, or the source device and the reader device may employ a subchannel selection procedure that utilizes a mapping relationship between occupied subchannels and available subchannels, or any combination thereof.

[0065] Figure 2 An example network architecture 200 (such as a disaggregated base station architecture, a disaggregated RAN architecture) that supports interference reduction techniques between passive wireless devices is shown. The network architecture 200 may illustrate an example for implementing one or more aspects of the wireless communication system 100. The network architecture 200 may include one or more CUs 160-a, which may communicate directly with the core network 130-a via a backhaul communication link 120-a, or indirectly with the core network 130-a through one or more disaggregated network entities 105 (such as a near-RT RIC 175-b via an E2 link, or a non-RT RIC 175-a associated with an SMO 180-a (such as an SMO framework), or both. The CU 160-a may communicate with one or more DUs 165-a via corresponding midhaul communication links 162-a (such as an F1 interface). The DU 165-a may communicate with one or more RUs 170-a via corresponding fronthaul communication links 168-a. The RU 170-a may be associated with a respective coverage area 110-a and may communicate with the UE 115-a via one or more communication links 125-a. In some implementations, the UE 115-a may be served by multiple RUs 170-a simultaneously.

[0066] Each of the network entities 105 of the network architecture 200 (such as CU 160-a, DU 165-a, RU 170-a, non-RT RIC 175-a, near-RT RIC 175-b, SMO 180-a, open cloud (O-Cloud) 205, open eNB (O-eNB) 210) may include one or more interfaces or may be coupled to one or more interfaces configured to receive or send signals (such as data, information) via a wired or wireless transmission medium. Each network entity 105 or an associated processor (such as a controller) that provides instructions to the interface of the network entity 105 may be configured to communicate with one or more of the other network entities 105 via the transmission medium. For example, these network entities 105 may include a wired interface that is configured to receive signals on a wired transmission medium or send signals to one or more of the other network entities 105 on a wired transmission medium. Additionally or alternatively, the network entity 105 may include a wireless interface, which may include a receiver, transmitter, or transceiver (such as an RF transceiver) configured to receive signals on a wireless transmission medium, or to send signals to one or more of the other network entities 105 on the wireless transmission medium, or both.

[0067] In some specific implementations, CU 160-a may host one or more higher layer control functions. Such control functions may include RRC, PDCP, SDAP, etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by CU 160-a. CU 160-a may be configured to handle user plane functionality (such as CU-UP), control plane functionality (such as CU-CP), or a combination thereof. In some specific implementations, CU 160-a may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). As needed, CU 160-a may be implemented to communicate with DU 165-a for network control and signaling.

[0068] DU 165-a may correspond to a logical unit that includes one or more functions (such as base station functions, RAN functions) for controlling the operation of one or more RUs 170-a. In some implementations, DU 165-a may at least partially host one or more of one or more aspects of an RLC layer, a MAC layer, and a PHY layer (such as a high PHY layer, such as modules for FEC encoding and decoding, scrambling, modulation and demodulation, etc.), which depends at least in part on functional splits, such as those defined by the Third Generation Partnership Project (3GPP). In some implementations, DU 165-a may further host one or more low PHY layers. Each layer may be implemented using an interface that is configured to communicate signals with other layers hosted by DU 165-a or with control functions hosted by CU 160-a.

[0069] In some implementations, lower layer functionality may be implemented by one or more RUs 170-a. For example, a RU 170-a controlled by a DU 165-a may correspond to a logical node that hosts RF processing functions or low PHY layer functions (such as performing fast Fourier transform (FFT), inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc.) or both based at least in part on functional splitting (such as lower layer functional splitting). In such an architecture, the RU 170-a may be implemented to handle over-the-air (OTA) communications with one or more UEs 115-a. In some implementations, real-time and non-real-time aspects of control plane communications and user plane communications with the RU 170-a may be controlled by the corresponding DU 165-a. In some implementations, such a configuration may enable the DU 165-a and CU 160-a to be implemented in a cloud-based RAN architecture (such as a vRAN architecture).

[0070] The SMO 180-a may be configured to support RAN deployment and provisioning of non-virtualized and virtualized network entities 105. For non-virtualized network entities 105, the SMO 180-a may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface (such as an O1 interface). For virtualized network entities 105, the SMO 180-a may be configured to interact with a cloud computing platform (such as O-Cloud 205) via a cloud computing platform interface (such as an O2 interface) to perform network entity lifecycle management (such as to instantiate virtualized network entities 105). Such virtualized network entities 105 may include, but are not limited to, CU 160-a, DU 165-a, RU 170-a, and near-RT RIC 175-b. In some specific implementations, the SMO 180-a may communicate (such as via an O1 interface) with components configured according to a 4G RAN. Additionally or alternatively, in some implementations, the SMO 180-a may communicate directly with one or more RUs 170-a via an O1 interface. The SMO 180-a may also include a non-RT RIC 175-a configured to support the functionality of the SMO 180-a.

[0071] The non-RT RIC 175-a may be configured to include logic functions that implement non-real-time control and optimization of RAN elements and resources, artificial intelligence (AI) or machine learning (ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 175-b. The non-RT RIC 175-a may be coupled or communicate with the near-RT RIC 175-b (such as via an A1 interface). The near-RT RIC 175-b may be configured to include logic functions that implement near-real-time control and optimization of RAN elements and resources through data collection and actions via an interface connecting one or more CUs 160-a, one or more DUs 165-a, or both, and the O-eNB 210 to the near-RT RIC 175-b (such as via an E2 interface).

[0072] In some implementations, in order to generate an AI / ML model to be deployed in the near-RT RIC 175-b, the non-RT RIC 175-a may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 175-b and may be received from a non-network data source or from a network function at the SMO 180-a or the non-RT RIC 175. In some implementations, the non-RT RIC 175-a or the near-RT RIC 175-b may be configured to tune RAN behavior or performance. For example, the non-RT RIC 175-a may monitor long-term trends and patterns of performance and employ an AI model or ML model to perform corrective actions through the SMO 180-a (such as via reconfiguration of O1) or via the generation of a RAN management policy (such as an A1 policy).

[0073] In some implementations, one or more devices, entities, or functionalities associated with the network architecture 200 may support one or more configuration-based or signaling-based mechanisms (such as one or more physical layers, such as lower layers, procedures) to avoid or mitigate interference between backscatter communications. For example, a source device and a reader device (each of the source device and the reader device may be an example of a UE 115 or a network entity 105) may communicate via a passive wireless device according to a passive wireless device that reflects communications from the source device to the reader device. In some aspects, such a passive wireless device may be an example of a UE 115 (with reduced capability (RedCap) or non-RedCap) that deploys a radio frequency identification (RFID) tag module or radio component, and the UE 115 may use the RFID tag module or radio component if it is in a power saving state (such as if the battery power of the UE 115 drops below a threshold battery power) or if low-power communication is performed (such as using a transmit power less than a threshold transmit power to transmit). In other words, UE 115 may be an RFID device, a device using a low complexity receiver, or a device equipped with an RFID tag radio, and any of such devices may be an example of a passive wireless device. A passive wireless device may convey additional information (such as information in addition to the information sent by the source device) to a reader device based on a backscatter modulation technique.

[0074] As described herein, information or signaling sent by a source device may be referred to or understood as a first message, and information or signaling transmitted by a passive wireless device may be referred to or understood as a second message. The first message may be associated with a signal x(n) (such as transmitted via a signal), and the second message may be associated with a signal s(n)x(n) (such as transmitted via a signal). In some implementations, a passive wireless device and a reader device may receive an indication of a communication signature in a communication signature set that is specific to backscatter communications from a source device to a reader device via a passive wireless device. Thus, the passive wireless device may transmit a second message associated with the signal s(n)x(n) based on the backscattered first message associated with the signal x(n) and based on the communication signature. A communication signature may refer to any unique or identifying aspect of wireless communication, such as a time domain code sequence or a power scaling factor that is specific to (such as unique to or dedicated to) backscatter communications from a passive wireless device.

[0075] Figure 3 An example signaling diagram 300 is shown that supports interference reduction techniques between passive wireless devices. The signaling diagram 300 can implement or be implemented to achieve aspects of the wireless communication system 100 or the network architecture 200. For example, the signaling diagram 300 illustrates communications between a source device 305 (such as a radio frequency source device), a reader device 310, and a passive wireless device 315-a (which can be an example of a tag such as an IoT tag). In some implementations, the source device 305, the reader device 310, and the passive wireless device 315-a can employ one or more configuration-based or signaling-based mechanisms according to which the devices can avoid or mitigate interference from other devices, such as interference 355 from the passive wireless device 315-b.

[0076] In some aspects, the passive wireless device 315 (which may generally refer to any one or more of the passive wireless device 315-a or the passive wireless device 315-b) may be an example of a passive IoT device, and may employ energy harvesting and backscatter communication to communicate with one or both of the source device and the reader device. In other words, the passive wireless device 315 may be an example of a passive IoT device, which may be various or various types of devices that rely on passive communication techniques such as backscatter communication. Using such techniques, manufacturers and networks can achieve low power and low cost. Further, in some commercial communication systems, UHF RFID systems may be deployed, which may also use backscatter communication. However, UHF RFID systems may be incompatible with some cellular systems such as NR systems. For example, an RFID system may operate using an ISM band, while an NR system may operate using a licensed band. Further, there is no defined or expected interference between these two different systems. Thus, the passive wireless device 315 may facilitate the use of passive IoT in NR, whereas UFH RFID may not be able to facilitate such functionality.

[0077] The passive wireless device 315 may support energy harvesting enabled communication services (EHECS) in a 5G system (5GS), and thus may be a battery-free device or otherwise have a limited energy storage device (such as a capacitor). The passive wireless device 315 may be a low-level device, such as a device level similar to an RFID device, a RedCap device, or an enhanced RedCap (eRedCap) device. Alternatively, the passive wireless device 315 may not be a RedCap device, and thus the described techniques may be applicable to non-RedCap implementations. For example, the passive wireless device 315 may be a mobile phone, a laptop computer, a smart watch, smart jewelry, a robot, a manufacturing component, a vehicle, an IoT tag, an antenna panel, a repeater, one or more patch antennas, a smart reflective surface (RIS), an IoT device, a narrowband (NB)-IoT device, an RFID device, a UE 115 (such as a UE 115 equipped with an RFID tag module or a radio component), a low complexity receiver, or an industrial IoT device (IIoT), etc., which are associated with IoT applications or are capable of relaying or reflecting communications between a source device 305 and a reader device 310. In addition to or as an alternative to backscatter communication-based passive IoT, where a battery-free device can harvest energy from ambient RF signaling and use the harvested energy to redirect the signaling (such as an RFID tag), the passive wireless device 315 can use energy harvesting to power components of the passive wireless device 315, such as an analog-to-digital converter (ADC), a mixer, or one or more oscillators. In some systems, an RFID reader can continuously transmit a command / write (CW) signal and can simultaneously receive a signal reflected or backscattered from an RFID tag.

[0078] The passive wireless device 315 may support identification, tracking, power supply, access control or connectivity management or location implementation, etc. In some 5G deployment scenarios, the passive wireless device 315 may support or be associated with one or more constraints on data rate, power consumption and density, and may support one or more procedures or technologies associated with onboarding (such as connection establishment), provisioning (such as connection management) and decommissioning (such as connection cancellation) of the passive wireless device 315. Further, the passive wireless device 315 may support one or more procedures or technologies associated with identification, authentication and authorization, access control, mobility management, security, and other communication mechanisms.

[0079] In an example where the passive wireless device 315 supports energy harvesting, the passive wireless device 315 may opportunistically harvest energy in the environment to charge a battery or otherwise obtain power to perform one or more operations (such as decoding, decryption, encryption, encoding, signal generation, or transmission). For example, the passive wireless device 315 may harvest or otherwise obtain energy from solar energy, thermal energy, or ambient radio frequency radiation, or any combination thereof, and store the harvested energy in a rechargeable battery. In some aspects, the passive wireless device 315 may support energy harvesting techniques to support operation on intermittently available energy harvested from the environment, because changes in the amount of harvested energy are expected. For example, a passive wireless device 315 (such as a NB-IOT device or an RFID device) may use energy harvested from solar energy to support one or more operations. Further, changes in the amount of traffic (such as data traffic or communication traffic) are expected. Therefore, if operating on intermittently available energy harvested from the environment, the passive wireless device 315 may not (or at least may not be expected to) maintain relatively long continuous reception or transmission.

[0080] The passive wireless device 315-a may reflect, relay, or backscatter communications from the source device 305 to the reader device 310, and in some aspects, may convey additional information (information other than that conveyed by the source device 305) to the reader device 310 via the reflected, relayed, or backscattered signals. For example, the source device 305 may transmit a signal via one or more of the communication beam 345-a, the communication beam 345-b, or the communication beam 345-c, and the passive wireless device 315-a may receive the signal from the source device 305 and may modulate the additional information onto the signal according to an information modulation method. In some implementations, the information modulation method employed by the passive wireless device 315-a (backscatter or scattering device) may be amplitude shift keying (ASK), according to which the passive wireless device 315-a may turn on reflection when transmitting an information bit "1" and may turn off reflection when transmitting an information bit "0".

[0081] For example, source device 305 may transmit a radio wave denoted as x(n), and passive wireless device 315-a may convey information bits of s(n)∈{0,1}. Thus, the signal received at reader device 310 may be defined by Equation 1 shown below.

[0082] y(n)=(h D1D2 (n)+σ f h D1T (n)h TD2 (n)s(n))x(n)+noise (1)

[0083] As shown in Formula 1, hD1D2 (n) may represent a channel 320 between the source device 305 and the reader device 310, σ f The reflection coefficient of the passive wireless device 315-a, h D1T (n) may represent a channel 325 between the source device 305 and the passive wireless device 315-a, TD2 y(n) may represent the channel 330 between the passive wireless device 315-a and the reader device 310, and noise may represent any channel noise that affects the signaling from the source device 305 to the reader device 310. Thus, if s(n)=0, reflections may be turned off at the passive wireless device 315-a, and the reader device 310 may receive a direct link signal from the source device 305 (and may not receive any reflected signals from the passive wireless device 315-a). In such a scenario where s(n)=0, y(n)=h D1D2 (n)x(n)+noise. Further, if s(n)=1, reflection may be turned on at the passive wireless device 315-a, and the reader device 310 may receive a superposition of both the direct link signal and the backscatter link signal, as shown in Equation 1. To receive the information bits sent by the passive wireless device 315-a, the reader device 310 may use the measured, indicated, estimated, or otherwise known h by treating or expecting the backscatter link signal as interference. D1D2 (n) decodes x(n). Reader device 310-a can decode x(n) by subtracting h from y(n). D1D2 (n)x(n) to detect the term σ f h D1T (n)h TD2 The existence of (n)s(n)x(n).

[0084] In some deployment scenarios, there may be multiple readers or multiple passive wireless devices 315 (multiple passive IoT devices or tags) within the system, and several problems or challenges associated with interference from backscatter communications may arise. For example, in a deployment where there are multiple readers and a single passive wireless device 315, if the reader uses relatively close subchannels for communication, the reflected signals or backscattered signals from the passive wireless device 315 may overlap in some parts, and interference to each reader may occur. In other words, some reflected signaling or backscattered signaling from the passive wireless device 315 may leak into adjacent subchannels. Therefore, interference may occur in a subchannel between two subchannels used for different command / write (CW) signals because reflected signaling or backscattered signaling from two different CW signals may leak into the middle subchannel. Such interference may adversely affect the decodability of the signal from the passive wireless device 315 at one or more readers in the system. As another example, in a deployment where there is a one-to-one mapping between passive wireless devices 315 and readers (such that each reader device 310 corresponds to or is associated with a specific passive wireless device 315, where each reader reads from a (different) passive wireless device 315), if two passive wireless devices 315 communicate through two readers (such as reflecting or backscattering communications for the two readers), the reflected signals or backscattered signals from the passive wireless devices 315 may cause interference with each other. For example, and as illustrated in the signaling diagram 300, the reader device 310 may experience (such as receive or measure) interference 355 (such as from reflected signaling or backscatter signaling from the passive wireless device 315-b).

[0085] Thus, in some implementations, the source device 305, the reader device 310, and the passive wireless device 315-a may support one or more configuration-based or signaling-based interference avoidance mechanisms to avoid, reduce, or mitigate the effects of the interference 355. The one or more configuration-based or signaling-based interference avoidance mechanisms may include source-side or reader-side operations and implementations, or may include passive wireless device-side (such as tag-side) operations and implementations, or any combination thereof. In some implementations, each passive wireless device 315 (such as each of the passive wireless device 315-a and the passive wireless device 315-b) may add or apply a communication signature 350 to the reflected signal from the passive wireless device. For example, the communication signature 350 may generally refer to any one or more of a communication signature 350-a associated with (such as specific to or unique to) the passive wireless device 315-a or a communication signature 350-b associated with (such as specific to or unique to) the passive wireless device 315-b. Thus, the passive wireless device 315-a may receive a first message 335 from the source device 305 and may send a second message 340 to the reader device 310 (via backscattering of the first message 335) based on the communication signature 350-a (such as based on applying the communication signature 350-a to reflected signaling or backscatter signaling).

[0086] Thus, each passive wireless device 315 in the system may add or apply a different communication signature 350 to the reflected signaling, which may enable the reader to accurately extract and decode the relevant messaging because each reader may be configured with or receive an indication of the communication signature 350 used by the associated passive wireless device 315. For example, the passive wireless device 315-a and the reader device 310 may receive an indication of the communication signature 350-a to be used by the passive wireless device 315-a, or may be configured with (and store in memory) the communication signature 350-a to be used by the passive wireless device 315-a, or any combination thereof. For example, a controller (such as a network entity 105, a UE 115, a reader device 310, or a source device 305) may configure or indicate the communication signature 350-a to one or both of the passive wireless device 315-a, the source device 305, or the reader device 310. The communication signature 350 may be indicated via L1, L2, or L3 signaling. For example, the passive wireless device 315-a, the source device 305, or the reader device 310 may receive an indication of the communication signature 350-a via downlink control information (DCI), sidelink control information (SCI), MAC control element (MAC-CE), RRC signaling, or any combination thereof. Additionally or alternatively, the passive wireless device 315 may self-select (such as autonomously select) the communication signature 350.

[0087] In some implementations, a particular communication signature 350 or a particular type of communication signature 350 may be indicated to the passive wireless device 315 based on the capabilities of the passive wireless device 315. For example, the passive wireless device 315 may be associated with a capability or class type (such as a tag class type), which in turn is associated with a capability, and the passive wireless device 315 may report (such as send) a capability information message to the controller to indicate the capability or class type of the passive wireless device 315. In a scenario where the passive wireless device 315 reports a class type associated with an underlying capability, the underlying capability may be derived, identified, determined, or selected by the controller based on a configuration at the controller. The passive wireless device 315 may send the capability information message to the controller via L1, L2, or L3 signaling. Device 310. The communication signature 350 may be indicated via L1, L2, or L3 signaling. For example, the passive wireless device 315-a may send the capability information message via DCI, SCI, MAC-CE, RRC signaling, or any combination thereof.

[0088] In some aspects, the communication signature 350 used by the passive wireless device 315 can be a time domain code sequence, such as a superimposed orthogonal code (OCC) sequence, a non-OCC sequence, an asynchronous sequence, or any combination thereof. In such aspects, the communication signature 350-a associated with the passive wireless device 315-a can be an example of a first time domain code sequence, and the communication signature 350-b associated with the passive wireless device 315-b can be an example of a second time domain code sequence different from the first time domain code sequence. In some specific implementations, the passive wireless device 315-a may apply the time domain code sequence to multiple repetitions of the first message 335 from the source device 305. For example, the passive wireless device 315-a may apply a corresponding element in the time domain code sequence to each consecutive repetition of the first message 335. The repetition of the first message 335 may be performed at a per bit level, a per group of bits level, or a per complete message or tag response level. By Figure 4 Additional details related to such application of a time-domain code sequence as a communication signature 350 are illustrated and described with reference to this figure.

[0089] Additionally or alternatively, the communication signature 350 used by the passive wireless device 315 can be a power scaling factor, such as a transmit power scaling factor. In such aspects, the communication signature 350-a associated with the passive wireless device 315-a can be an example of a first power scaling factor, and the communication signature 350-b associated with the passive wireless device 315-b can be an example of a second power scaling factor different from the first power scaling factor. In some implementations, the particular power scaling factor configured at the passive wireless device 315 can be configured according to a plurality of available or possible power scaling factors. In a specific implementation in which the passive wireless device 315-a and the passive wireless device 315-b use different power scaling factors, the source device 305 may send a CW signal to both the passive wireless device 315-a and the passive wireless device 315-b, each of the passive wireless device 315-a and the passive wireless device 315-b may multiply the CW signal by the corresponding power scaling factor, and the reader device 310 may perform continuous cancellation to distinguish and extract the two backscattered signals from the passive wireless device 315-a and the passive wireless device 315-b.

[0090] In such implementations, the reader device 310 may act as a non-orthogonal multiple access (NOMA) receiver. In some aspects, the power scaling factor assigned to each of the passive wireless device 315-a and the passive wireless device 315-b and the successive cancellation performed by the reader device 310 may be based on the importance or priority of the data of each of the passive wireless device 315-a and the passive wireless device 315-b. For example, the configured, assigned, selected, or indicated power scaling factor may be a function of the importance, priority, or quality of service (QoS) of the reflected signal or the backscattered signal, or the importance, priority, or QoS of the passive wireless device 315 itself, or any combination thereof.

[0091] Additionally or alternatively, the source device 305 and the reader device 310 may support a power control configuration or procedure according to which the source device 305 and the reader device 310 each use a specific power control configuration on a specific subchannel (such as when another reader device is transmitting on the same subchannel). In such specific implementations in which the source device 305 and the reader device 310 employ such power control configurations, the source device 305 and the reader device 310 may effectively support NOMA-like transmissions. Further, the power control configuration supported by the source device 305 and the reader device 310 may be separate from other power control operations also supported at these devices. For example, the power control configuration may be different from an uplink control procedure used by the UE 115 (such as an uplink power control associated with p0+10log10(#RBs)+alpha+PL). For example, the power control configuration used by the source device 305 and the reader device 310 for interference avoidance may be specifically associated with (such as dedicated to) a scenario in which the source device 305 and the reader device 310 are attempting to mitigate interference associated with backscatter communications via the passive wireless device 315-a.

[0092] The power control configuration used by the source device 305 and the reader device 310 for interference avoidance associated with backscatter communications via the passive wireless device 315-a can be a function of the subchannels (or number of subchannels) used by the source device 305 and the reader device 310, proximity to other devices in the system, power usage by other devices in the system, or any combination thereof. In some aspects, proximity to other devices in the system can include information associated with the location or distance of an active device (such as an active reader UE 115, such as a reader UE 115 that is actively transmitting) relative to the source device 305, the reader device 310, or the passive wireless device 315-a. In some aspects, power usage by other devices in the system can include information associated with power usage by other reader UEs 115 in the system, and such information can be obtained via an indication (such as from a controller) or by computing or calculating one or more reference signal received power (RSRP) measurements between UEs 115, which can be associated in part with the class type (such as tag class) of the passive wireless device 315-a.

[0093] Further, although described and illustrated separately herein as a source device 305 and a reader device 310, the source device 305 and the reader device 310 may be part of the same device or arranged in juxtaposition. In a scenario where the source device 305 and the reader device 310 are part of the same device, such same device may be collectively referred to herein as a reader, such as a reader operating, including, or associated with an RF source (such as an RF source UE). Therefore, the example implementations described herein may be applicable to a single static deployment or a dual static deployment, or any combination of a single static deployment and a dual static deployment. Similarly, the example implementations may be applicable to reader-side operations, RF source-side operations, tag-side operations, or any combination thereof.

[0094] Figure 4 An example code-based communication signature 400 that supports interference reduction techniques between passive wireless devices is shown. The code-based communication signature 400 can implement or be implemented to achieve aspects of the wireless communication system 100, the network architecture 200, or the signaling diagram 300. For example, the passive wireless device 315-a and the passive wireless device 315-b (which can be such as through Figure 3 Examples of passive wireless devices 315-a and passive wireless devices 315-b illustrated and described with reference to the figure) may apply a code-based communication signature 400. In other words, for example, a communication signature 350-a associated with the passive wireless device 315-a and a communication signature 350-b associated with the passive wireless device 315-b may each be an example of a code-based communication signature 400, such as a time-domain code sequence.

[0095] In an implementation where the passive wireless device 315-a and the passive wireless device 315-b use a time domain code sequence, one or more readers (such as the source device 305) may transmit repeated bits, groups of bits, or blocks (such as an entire or complete message), and the passive wireless device 315-a and the passive wireless device 315-b may modulate each repetition with an element of a time domain code sequence (such as an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, such as an asynchronous CDMA-like code sequence). For example, and as Figure 4As illustrated, the communication signature 350-a associated with the passive wireless device 315-a may be a time domain code sequence {+1, +1, ...}, and the communication signature 350-b associated with the passive wireless device 315-b may be a time domain code sequence {+1, -1, ...}. Thus, the passive wireless device 315-a may apply the first element "+1" from the communication signature 350-a to the first repetition 405-a of the repetition message X received from the source device 305, apply the second element "+1" from the communication signature 350-a to the second repetition 405-b of the repetition message X received from the source device 305, and so on. Similarly, the passive wireless device 315-b may apply the first element "+1" from the communication signature 350-b to the first repetition 410-a of the repeated message Y received from the source device 305, apply the second element "-1" from the communication signature 350-b to the second repetition 410-b of the repeated message Y received from the source device 305, and so on.

[0096] In such an example, the reader device 310 may receive a first signal Z1=X+Y+noise1 at a first timing, and may receive a second signal Z2=X-Y+noise2 at a second timing. Therefore, to obtain the signal X in this example, the reader device 310 may add Z1+Z2 to calculate 2X+noise1+noise2. The reader device 310 may divide by 2 to obtain X+(noise1+noise2) / 2. In general, the reader device 310 may receive repetitions of a set of messages (such as X and Y), and may extract the message X in the following manner: multiply each repetition of the repetition of the message set with the conjugate of the time domain code sequence assigned to the repetition associated with the message X (such as the conjugate of the communication signature 350-a) to obtain a set of products, and sum or add the set of products to separate (e.g., identify or obtain) the message X.

[0097] In some aspects, X may refer to the entire message X, and thus, the described application of elements of the time-domain code sequence to repetitions of message X may refer to repetitions of each read / write block such that the passive wireless device 315 repeats "response". In other words, for the time-domain code sequence [1 -1], the reader may process two repetitions of the complete message "ABCDEF" as "AB CD EFABCDEF", and for each response application of the time-domain code sequence, the output may be "ABCDEF -AB -C -D -E -F" (such that the first repetition of the complete message is multiplied by +1, and the second repetition of the complete message is multiplied by -1). In such a per-response scenario, the reader may process across 2 response blocks of 2 responses from the passive wireless device 315.

[0098] Additionally or alternatively, the passive wireless device 315 may apply a time domain code sequence for each bit or each group of bits (so that the reader may repeat at each bit level and the passive wireless device 315 may apply the time domain code sequence at each bit level, which may be consistent with an asynchronous CDMA design). In other words, the passive wireless device 315 may apply an OCC sequence or a non-OCC sequence for each bit or each group of bits. In a specific implementation in which the passive wireless device 315 applies a time domain code sequence for each bit, the output may be "AA B -BC -CD -DE -EF -F". In such a specific implementation, each repetition of the message may correspond to a bit of the message, and the passive wireless device 315 may apply a corresponding element of the time domain code sequence to each consecutive bit level repetition of the message. In such a per-bit scenario, processing across the passive wireless device 315 may be performed for each bit, so that the reader selects once every 2 bits and processes the selected 2 bits.

[0099] The time domain code sequence may include various types of sequences, and which sequences are available for use may depend on whether the repetition is performed at a per-bit level, per-group or block bit level, or per-response level. For example, the time domain code sequence may be a superposition code based on at least one of a King code or sequence, an m-sequence or code, a Walsh or Hadamard code or sequence, a DFT code or sequence, a Zadoff-Chu sequence, or a Reed-Solomon code or sequence. Additionally or alternatively, one or more of the source device 305, the reader device 310, or the passive wireless device 315 may support modulation or encoding of bits into a series of orthogonal sequences, such that two passive wireless devices 315 may use two orthogonal sequences to deliver their respective "0" bits and "1" bits. Thus, the time domain code sequence may include using pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), or pulse code modulation (PCM) to modulate or encode one or more bits (or the entire response) into a King code or sequence, an m-sequence or code, a Walsh or Hadamard code or sequence, a DFT code or sequence, a Zadoff-Chu sequence, or a Reed-Solomon code or sequence to achieve such orthogonality.

[0100] In some implementations, to separate or distinguish passive wireless devices 315 (such as RFID tags), each passive wireless device 315 can be assigned a different set of sequences from a sequence pool to reduce or mitigate interference between passive wireless devices 315, which can enable a reader to identify, select, or determine the source of a transmitted or backscattered signal of a passive wireless device 315 (such as an RFID tag). To generate orthogonal sequences reflected by M passive wireless devices 315, the passive wireless device 315 can use 2M different pulse positions or 2M amplitudes. In an implementation in which 2M different pulse positions are used (which can be an implementation in which PPM is used), the passive wireless device 315 can divide time into 2M positions, where one of the 2M positions can have a non-zero signal, and the rest of the positions can be zero signals. In an implementation where 2M amplitudes are used (which may be an implementation where PAM is used), each passive wireless device 315 may encode data in a bit-by-bit manner (such as encoding bits into a sequence of M transmissions with a single position having a non-zero value), and the passive wireless device 315 may be assigned 2 of the 2M possibilities to encode two bits. Other passive wireless devices 315 may be assigned 2 of the remaining 2M-2 sequences.

[0101] For example, assuming 2 passive wireless devices 315 (such as 2 tags), a bit may be sent using the sequence {OFF, OFF, OFF, ON}; {OFF, OFF, ON, OFF}, {OFF, ON, OFF, OFF}, or {ON, OFF, OFF, OFF}. A first passive wireless device 315 (such as RFID tag 1) may be provided (such as configured at it or signaled to it) with two sequences to transmit its bit "0" or "1". For example, a "0" of the first passive wireless device 315 may be associated with the sequence {OFF, OFF, OFF, ON}, while a "1" may be associated with the sequence {OFF, OFF, ON, OFF}. For a second passive wireless device 315 (such as RFID tag 2), a "0" may be associated with the sequence {OFF, ON, OFF, OFF}, while a "1" may be associated with the sequence {ON, OFF, OFF, OFF}. Thus, the reader can separate, identify or otherwise determine whether the transmission is from a first passive wireless device 315 (such as RFID tag 1) or a second passive wireless device 315 (such as RFID tag 2), or both, and can decode one or both accordingly.

[0102] Figure 5An example frequency domain response 500 of backscatter communications supporting interference reduction techniques between passive wireless devices is shown. Aspects of the wireless communication system 100, network architecture 200, signaling diagram 300, or code-based communication signature 400 may be implemented or achieved. For example, a system of readers and passive wireless devices 315 may use a set of subchannels 505 in close proximity (which may generally refer to any one or more of subchannels 505-a, subchannels 505-b, subchannels 505-c, subchannels 505-d, subchannels 505-f, or subchannels 505-g) and may support one or more configuration-based or signaling-based mechanisms by which the reader and passive wireless device 315 may avoid or mitigate interference between backscatter communications.

[0103] For example, reader A may use subchannel 505-b to transmit CW signal 510-a, reader B may use subchannel 505-d to transmit CW signal 510-b, and reader C may use subchannel 505-f to transmit CW signal 510-c. In some scenarios, backscatter response 515-a for reader A may leak into subchannel 505-a and subchannel 505-c, backscatter response 515-b for reader B may leak into subchannel 505-c and subchannel 505-e, and backscatter response 515-c for reader C may leak into subchannel 505-e and subchannel 505-g. In such scenarios, interference between backscatter communications may occur at subchannel 505-c and subchannel 505-e.

[0104] To avoid or mitigate such interference received or experienced at the reader, one or more passive wireless devices 315 may support and implement receive filtering or transmit filtering or both. In other words, the passive wireless device 315 may support receive filtering (such as receive side filtering) capabilities or transmit filtering (such as transmit side filtering) capabilities or both. Therefore, according to each tag capability or tag category (wherein the category may be associated with the ability to filter and possibly configurable receive or transmit filtering), the reader, network entity 105, UE 115 or other controller may send an indication of the bandwidth information that can be configured to the passive wireless device 315, and the passive wireless device 315 may use the indication of the configurable bandwidth information to reduce interference to other readers in the system.

[0105] For example, the passive wireless device 315 may receive an indication of a bandwidth (such as a particular subchannel 505) over which the source device 305 is to send a message to the passive wireless device 315 for backscattering, and the passive wireless device 315 may filter out RF energy received outside the indicated bandwidth on the receive side (such as at the front end of the passive wireless device 315) or on the transmit side, depending on capabilities or configuration. In some implementations (such as implementations in which the passive wireless device 315 supports energy harvesting), receive-side filtering may occur prior to energy harvesting at the passive wireless device 315. In such implementations, the passive wireless device 315 may not be able to use the filtered RF energy for energy harvesting. Therefore, in some other implementations, the passive wireless device 315 may perform transmit-side filtering to enable the passive wireless device 315 to harvest energy from interfering signals (such as RF energy from signals received outside the indicated bandwidth from other devices and readers), and then backscatter (only) signals received within the indicated bandwidth. Thus, the passive wireless device 315 may avoid contributing energy to subchannels 505 other than the particular subchannel 505 on which the corresponding reader transmits a CW signal. In one example, based on such transmit-side filtering, the backscatter responses 515-a may remain combined within subchannel 505-b, but the corresponding passive wireless device 315 may use RF energy received via subchannel 505-a, subchannel 505-b, and subchannel 505-c (of possible other subchannels 505).

[0106] Additionally or alternatively, the reader may perform a listen-before-talk (LBT) procedure to select one or more subchannels 505 to use. For example, reader A may begin the process by selecting a subchannel 505, such as subchannel 505-b. Reader B may perform an LBT procedure (such as listening or eavesdropping) and perform detection on a configured, identified, selected, measured, or otherwise determined set of subchannels 505, and if the set of subchannels 505 is not occupied or utilized (or includes at least some available subchannels 505), reader B may make a list of available subchannels 505 and select a subchannel from the list for reading use. In some implementations, the selected subchannel 505 (such as subchannel 505-d) may be a function of the subchannels 505 that are used or occupied. In one example, reader B may select subchannel 505-f to avoid any interference with reader A (without the assistance of other interference avoidance mechanisms).

[0107] Thus, in some implementations, readers (such as source device 305 and reader device 310) may support a configuration according to which a particular set of subchannels 505 is available if another particular set of subchannels 505 is occupied. In such implementations, such configuration may be associated with a mapping relationship that indicates a correspondence between occupied sets of subchannels 505 and available sets of subchannels 505. In other words, the mapping relationship may indicate that if a first set of subchannels 505 is measured or otherwise determined to be occupied, a second set of subchannels 505 is available for use; if a third set of subchannels 505 is measured or otherwise determined to be occupied, a fourth set of subchannels 505 is available for use, and so on, wherein the input of the mapping relationship is the occupied set of subchannels 505, and the output of the mapping relationship indicates the corresponding available set of subchannels 505. For example, if reader B is using subchannel X, reader A may use subchannel Y.

[0108] Such a relationship between a "list of used subchannels" and a "subchannel that is allowed to be used given the list of used subchannels" may be defined by a network specification and indicated via one or more tables, configured by the network entity 105 or another control unit that controls a set of readers (such as reader A, reader B, and reader C), or negotiated and agreed upon by the readers via an RRC connection between these readers (such as via a side link or via another link, such as a link dedicated to negotiating and agreeing on such mapping relationships, or via a link on which the reader can communicate with the reader as a reader). In some aspects, the mapping relationship may be associated with an increment n. For example, if reader B is using subchannel X=x, reader A may use subchannel Y=x+n. Further, in a specific implementation in which the mapping relationship is indicated or otherwise conveyed via signaling, the indication of the mapping relationship may be sent or received via DCI, SCI, a shared data channel, a licensed data channel, MAC-CE, RRC signaling, or any combination thereof.

[0109] Figure 6 An example process flow 600 for supporting interference reduction techniques between passive wireless devices is shown. The process flow 600 may implement or be implemented to achieve aspects of the wireless communication system 100, the network architecture 200, the signaling diagram 300, the code-based communication signature 400, or the frequency domain response 500. For example, the process flow 600 illustrates backscatter communication from a source device 305 to a reader device 310 via a passive wireless device 315-a, where the source device, the reader device, and the passive wireless device may be as described above. Figures 1 to 5Examples of source devices 305, reader devices 310, and passive wireless devices 315-a illustrated or described with reference to these figures. In some implementations, such devices can support one or more configuration-based or signaling-based interference avoidance mechanisms, according to which such devices can avoid or mitigate interference associated with backscatter communications from the source device 305 to the reader device 310 via the passive wireless device 315-a.

[0110] In the following description of process flow 600, operations (such as reporting or providing) may be performed in a different order than shown, or operations performed by the example device may be performed in a different order or at a different time. For example, certain operations may also be omitted from process flow 600, or other operations may be added to process flow 600. Further, although some operations or signaling are shown as occurring at different times for discussion purposes, these operations may actually occur simultaneously.

[0111] At 605, the passive wireless device 315-a may send an indication of capabilities of the passive wireless device 315-a associated with interference avoidance for backscatter communications. In some implementations, the passive wireless device 315-a may send the indication of capabilities to a controller (such as a source device 305, a reader device 310, a network entity 105, a UE 115, or another control device with which the passive wireless device 315-a may establish a connection) via a capabilities information message. Thus, although the indication of capabilities is illustrated as being transmitted from the passive wireless device 315-a to the source device 305, the passive wireless device 315-a may additionally or alternatively send the indication of capabilities to one or more other devices.

[0112] At 610, the source device 305 may send an indication of a communication signature in the communication signature set to the reader device 310, the communication signature being specific to backscatter communications from the source device 305 to the reader device 310 via the passive wireless device 315-a. In some implementations, the communication signature may be associated with interference avoidance for backscatter communications. The communication signature may be a time domain code sequence or a power scaling factor. The source device 305 may send an indication of the communication signature via a wired or wireless link and via any one or more of L1, L2, or L3 signaling. Additionally or alternatively, the communication signature may be stored locally at the reader device 310 (such as in a memory).

[0113] At 615, the source device 305 may send an indication of a communication signature in the communication signature set to the passive wireless device 315-a, the communication signature being specific to backscatter communications from the source device 305 to the reader device 310 via the passive wireless device 315-a. In some implementations, the communication signature may be associated with interference avoidance for backscatter communications. The communication signature may be a time domain code sequence or a power scaling factor. The source device 305 may send an indication of the communication signature via a wired or wireless link and via any one or more of L1, L2, or L3 signaling. Additionally or alternatively, the communication signature may be stored locally at the passive wireless device 315-a (such as in a memory).

[0114] At 620, the source device 305 may select a subchannel for backscatter communication. In some implementations, the source device 305 may measure whether the first set of subchannels is occupied according to an energy detection or LBT procedure at the source device 305, and may select a subchannel from a second set of subchannels, wherein the second set of subchannels is associated with the first set of subchannels according to a mapping relationship between occupied subchannels and available subchannels. Although shown as being performed by the source device 305, the reader device 310 (if different from the source device 305) may additionally or alternatively select a subchannel for backscatter communication.

[0115] At 625, the source device 305 can send to the passive wireless device 315-a an indication of a bandwidth associated with a first message to be transmitted by the passive wireless device 315-a via backscatter. In some implementations, the passive wireless device 315-a can use the indication of the bandwidth to frequency-domain filter the backscatter communications.

[0116] At 630, the source device 305 may send a first message to the reader device 310 via backscatter from the passive wireless device 315-a in accordance with the communication signature. For example, the source device 605 may send the first message to the passive wireless device 315-a to apply the communication signature. Thus, the source device 305 may send the first message as a result of sending an indication of the communication signature, or in a manner that facilitates application of the communication signature at the passive wireless device 315-a, such as by repetition at a bit level, a bit group level, or a response level. Additionally or alternatively, the source device 305 may send the first message in accordance with the communication signature by applying a power scaling factor associated with backscatter communication at the source device 305.

[0117] The passive wireless device 315-a may apply the communication signature at 635. For example, the passive wireless device 315-a may apply a power scaling factor, a time domain code sequence, or a filtering technique associated with avoiding or mitigating interference associated with backscatter communications from the passive wireless device 315-a.

[0118] At 640, the passive wireless device 315-a may perform energy harvesting using first radio frequency energy received within the indicated bandwidth associated with the first message and using second radio frequency energy received outside the bandwidth associated with the first message. For example, if the passive wireless device 315-a employs a power scaling factor, a time domain code sequence, or a transmit side filtering technique for interference avoidance, the passive wireless device 315-a may use radio frequency energy received at the passive wireless device 315-a regardless of whether the energy is received within or outside of the band of the first message.

[0119] At 645, the passive wireless device 315-a may filter the second RF energy received outside the bandwidth associated with the first message to focus the backscatter of the first message into the bandwidth associated with the first message. Thus, the passive wireless device 315-a may avoid or reduce the extent of leakage of reflected signals or backscattered signals into one or more adjacent subchannels.

[0120] At 650, the passive wireless device 315-a may transmit a second message to the reader device 310 via backscatter of the first message and in accordance with the communication signature. For example, the passive wireless device 315-a may transmit the second message to the reader device 310 using a power scaling factor, using a time domain code sequence, or using a filtering technique that avoids or mitigates interference associated with backscatter by the passive wireless device 315-a.

[0121] At 655, the reader device 310 may extract (such as identify, decode, or separate) the second message from the signaling received at the reader device 310. In some implementations, the reader device 310 may extract the second message based on successive cancellation associated with the power scaling factor used by the passive wireless device 315-a. Additionally or alternatively, the reader device 310 may extract the second message based on multiplying a set of messages with a conjugate of a time domain code sequence applied by the passive wireless device 315-a, and adding the set of products to obtain the second message. In such implementations where the passive wireless device 315-a uses a time domain code sequence, the reader device 310 may extract the second message using the time domain code sequence of the passive wireless device 315-a and the time domain code sequences of one or more other passive wireless devices 315. For example, the reader device 310 may receive an indication of, or otherwise determine, a respective time domain code sequence used by each of the plurality of passive wireless devices 315, and may use the set of time domain code sequences to extract messages backscattered from one or more of the plurality of passive wireless devices 315.

[0122] Figure 7Block diagram 700 of an example device 705 supporting interference reduction techniques between passive wireless devices is shown. Device 705 may communicate (such as wirelessly) with one or more network entities (such as one or more components of one or more network entities 105), one or more UEs 115, or any combination thereof. Device 705 may include components for two-way voice and data communications, including components for sending communications and receiving communications, such as a communication manager 720, an input / output (I / O) controller 710, a transceiver 715, an antenna 725, a memory 730, code 735, and a processor 740. These components may be in electronic communication or otherwise coupled (such as operatively, communicatively, functionally, electronically, electrically) via one or more buses (such as bus 745).

[0123] I / O controller 710 can manage input signals and output signals of device 705. I / O controller 710 can also manage peripheral devices that are not integrated into device 705. In some implementations, I / O controller 710 can represent a physical connection or port to an external peripheral device. In some implementations, I / O controller 710 can utilize an operating system, such as or another known operating system. Additionally or alternatively, the I / O controller 710 may represent or interact with a modem, keyboard, mouse, touch screen, or similar device. In some implementations, the I / O controller 710 may be implemented as part of a processor or processing system (such as processor 740). In some implementations, a user may interact with the device 705 via the I / O controller 710 or via hardware components controlled by the I / O controller 710.

[0124] In some implementations, the device 705 may include a single antenna 725. However, in some other implementations, the device 705 may have more than one antenna 725, which can concurrently send or receive multiple wireless transmissions. The transceiver 715 can communicate bidirectionally via one or more antennas 725, wired or wireless links, as described herein. For example, the transceiver 715 may represent a wireless transceiver and can communicate bidirectionally with another wireless transceiver. The transceiver 715 may also include a modem for modulating packets, providing the modulated packets to one or more antennas 725 for transmission, and for demodulating packets received from one or more antennas 725.

[0125] In some implementations, the transceiver 715 may include one or more interfaces, such as one or more interfaces coupled to one or more antennas 725 configured to support various receiving or obtaining operations, or one or more interfaces coupled to one or more antennas 725 configured to support various sending operations or output operations, or a combination thereof. In some implementations, the transceiver 715 may include or be configured to be coupled to one or more processors or memory components that are operable to: perform or support operations based on received or obtained information or signals; or generate information or other signals for transmission or other output, or any combination thereof. In some implementations, the transceiver 715, or the transceiver 715 and one or more antennas 725, or the transceiver 715 and one or more antennas 725 and one or more processors or memory components (such as a processor 740, or a memory 730, or both) may be included in a chip or chip component installed in the device 705.

[0126] The memory 730 may include random access memory (RAM) and read-only memory (ROM). The memory 730 may store computer-readable, computer-executable code 735 including instructions that, when executed by the processor 740, cause the device 705 to perform various functions described herein. The code 735 may be stored in a non-transitory computer-readable medium such as a system memory or another type of memory. In some implementations, the code 735 may not be directly executable by the processor 740, but may cause a computer (such as when compiled and executed) to perform the functions described herein. In some implementations, the memory 730 may include, among other things, a basic I / O system (BIOS) that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0127] The processor 740 may include an intelligent hardware device (such as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a central processing unit (CPU), a field programmable gate array (FPGA), a microcontroller, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some specific implementations, the processor 740 may be configured to operate a memory array using a memory controller. In some specific implementations, the memory controller may be integrated into the processor 740. The processor 740 may be configured to execute computer-readable instructions stored in a memory (such as a memory 730) to enable the device 705 to perform various functions (such as functions or tasks that support interference reduction techniques between passive wireless devices). For example, the device 705 or a component of the device 705 may include a processor 740 and a memory 730 coupled to the processor 740, and the processor 740 and the memory 730 are configured to perform various functions described herein. The processor 740 may be an example of a cloud computing platform (such as one or more physical nodes and supporting software such as an operating system, a virtual machine, or a container instance), which may host functions (such as by executing code 735) to perform the functions of the device 705. Processor 740 can be any suitable processor or processors capable of executing scripts or instructions of one or more software programs stored in device 705, such as within memory 730. In some implementations, processor 740 can be a component of a processing system.

[0128] A processing system may generally refer to a system or series of machines or components that receive inputs and process those inputs to produce a set of outputs that may be delivered to other systems or components (e.g., device 705). For example, a processing system of device 705 may refer to a system that includes various other components or subcomponents of device 705, such as processor 740, or transceiver 715, or communication manager 720, or other components or combinations of components of device 705. A processing system of device 705 may interface with other components of device 705 and may process information (such as inputs or signals) received from other components or output information to other components. For example, a chip or modem of device 705 may include a processing system and one or more interfaces for outputting information or for obtaining information or both.

[0129] The one or more interfaces may be implemented as or otherwise include a first interface configured to output information and a second interface configured to obtain information, or the same interface configured to output information and obtain information, as well as other specific implementations. In some specific implementations, the one or more interfaces may refer to an interface between a processing system of a chip or modem and a transmitter, so that the device 705 can send information output from the chip or modem. Additionally or alternatively, in some specific implementations, the one or more interfaces may refer to an interface between a processing system of a chip or modem and a receiver, so that the device 705 can obtain information or signal input, and the information can be passed to the processing system. Those of ordinary skill in the art will readily recognize that the first interface may also obtain information or signal input, and the second interface may also output information or signal output.

[0130] The communication manager 720 may support wireless communications at a passive wireless device according to examples as disclosed herein. For example, the communication manager 720 may be configured as or otherwise support a component for receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communications from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 720 may be configured as or otherwise support a component for receiving a first message from a source device. The communication manager 720 may be configured as or otherwise support a component for sending a second message to a reader device via backscatter of the first message and according to the communication signature.

[0131] In some implementations, the communication manager 720 can be configured as or otherwise support means for sending an indication of capabilities of a passive wireless device associated with interference avoidance for backscatter communications, wherein the communication signature is associated with the capabilities of the passive wireless device.

[0132] In some implementations, to support receiving an indication of a communication signature, the communication manager 720 can be configured as or otherwise support means for receiving an indication of a time-domain code sequence, wherein the communication signature includes the time-domain code sequence.

[0133] In some implementations, to support sending a second message via backscatter of a first message and according to a communication signature, the communication manager 720 can be configured as or otherwise support means for applying a time domain code sequence to a set of multiple repetitions of the first message.

[0134] In some implementations, the time-domain code sequence is associated with a sequence of elements. In some implementations, corresponding elements in the sequence of elements are applied to each consecutive repetition in the set of multiple repetitions of the first message.

[0135] In some implementations, the time domain code sequence is an overlaid orthogonal code (OCC) sequence, a non-OCC sequence, or an asynchronous code sequence.

[0136] In some implementations, the time-domain code sequence is applied for each bit, each group of bits, or each response from a passive wireless device.

[0137] In some implementations, to support receiving an indication of a communication signature, the communication manager 720 can be configured as or otherwise support means for receiving an indication of a power scaling factor, wherein the communication signature includes the power scaling factor.

[0138] In some implementations, to support sending a second message via backscatter of a first message and according to a communication signature, the communication manager 720 may be configured as or otherwise support a component for applying a power scaling factor to the second message, wherein the communication signature includes the power scaling factor.

[0139] In some implementations, the power scaling factor is associated with a first priority or a first quality of service (QoS) associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the first message.

[0140] In some implementations, the communications manager 720 can be configured as or otherwise support means for receiving an indication of a bandwidth associated with the first message, wherein frequency domain filtering of backscatter communications from the passive wireless device is associated with the indication of the bandwidth.

[0141] In some implementations, the communication manager 720 may be configured as or otherwise support means for performing energy harvesting using first radio frequency energy received within a bandwidth associated with a first message and using second radio frequency energy received outside a bandwidth associated with the first message. In some implementations, the communication manager 720 may be configured as or otherwise support means for filtering the second radio frequency energy received outside a bandwidth associated with the first message to focus backscatter of the first message to the bandwidth associated with the first message.

[0142] In some implementations, the first message corresponds to a first radio wave associated with a first set of bits, and the second message corresponds to a second radio wave associated with a second set of bits. In some implementations, backscattering by the passive wireless device is associated with amplitude shift keying modulation of the first set of bits with the second set of bits via selective reflection by the passive wireless device.

[0143] Additionally or alternatively, the communication manager 720 may support wireless communications at the reader device according to examples as disclosed herein. For example, the communication manager 720 may be configured as or otherwise support means for receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 720 may be configured as or otherwise support means for receiving a message via backscatter from a passive wireless device according to the communication signature.

[0144] In some implementations, to support receiving an indication of a communication signature, the communication manager 720 can be configured as or otherwise support means for receiving an indication of a time domain code sequence for a passive wireless device, wherein the communication signature includes the time domain code sequence for the passive wireless device.

[0145] In some implementations, to support receiving a message via backscatter from a passive wireless device and based on a communication signature, the communication manager 720 may be configured as or otherwise support means for receiving radio frequency signaling associated with a set of multiple repetitions of a set of messages, the set of multiple repetitions of the set of messages including a respective set of multiple repetitions for each message in the set of messages, wherein the set of messages includes the message. In some implementations, to support receiving a message via backscatter from a passive wireless device and based on a communication signature, the communication manager 720 may be configured as or otherwise support means for extracting the message from the radio frequency signaling based on a time domain code sequence.

[0146] In some implementations, to support extracting a message from RF signaling, the communication manager 720 may be configured as or otherwise support means for multiplying each repetition in a set of multiple repetitions of a set of messages with a conjugate of a time-domain code sequence to obtain a set of multiple products. In some implementations, to support extracting a message from RF signaling, the communication manager 720 may be configured as or otherwise support means for adding a set of multiple products to obtain the message.

[0147] In some implementations, each message in the message set is associated with reflected signaling from a different passive reflective device. In some implementations, each passive wireless device is associated with a different time domain code sequence.

[0148] In some implementations, the time domain code sequence is a superimposed orthogonal code (OCC) sequence, a non-OCC sequence, or an asynchronous code sequence. In some implementations, the time domain code sequence is applied for each bit, each group of bits, or each response from a passive wireless device.

[0149] In some implementations, to support receiving an indication of a communication signature, the communication manager 720 can be configured as or otherwise support means for receiving an indication of a power scaling factor for a passive wireless device, wherein the communication signature includes a power scaling factor for the passive wireless device.

[0150] In some implementations, to support receiving a message via backscatter from a passive wireless device and according to a communication signature, the communication manager 720 may be configured as or otherwise support means for receiving radio frequency signaling associated with a message set, wherein the message set includes the message. In some implementations, to support receiving a message via backscatter from a passive wireless device and according to a communication signature, the communication manager 720 may be configured as or otherwise support means for extracting the message from the radio frequency signaling according to a successive cancellation technique associated with a power scaling factor.

[0151] In some implementations, each message in the message set is associated with reflected signaling from a different passive reflective device. In some implementations, each passive wireless device is associated with a different power scaling factor.

[0152] In some implementations, the power scaling factor is associated with a first priority or a first quality of service (QoS) associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0153] In some embodiments, to support receiving an indication of a communication signature, the communication manager 720 may be configured as or otherwise support a component for receiving an indication of a power scaling factor of a source device, wherein the communication signature includes a power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices that use the same subchannel as used by the source device and the reader device.

[0154] In some embodiments, the power scaling factor of the source device is associated with a sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0155] In some implementations, the communication manager 720 can be configured as or otherwise support means for measuring whether the first set of subchannels is occupied based on energy detection measurements at the reader device. In some implementations, the communication manager 720 can be configured as or otherwise support means for selecting subchannels for backscatter communication from the source device to the reader device via the passive wireless device from a second set of subchannels, wherein the second set of subchannels is associated with the first set of subchannels based on a mapping relationship between occupied subchannels and available subchannels.

[0156] Additionally or alternatively, the communication manager 720 may support wireless communications at the source device according to examples as disclosed herein. For example, the communication manager 720 may be configured as or otherwise support means for sending an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from the source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 720 may be configured as or otherwise support means for sending a message to the reader device via backscatter from the passive wireless device according to the communication signature.

[0157] In some implementations, the communication manager 720 can be configured as or otherwise support means for receiving an indication of capabilities of a passive wireless device associated with interference avoidance for backscatter communications, wherein the communication signature is associated with the capabilities of the passive wireless device.

[0158] In some implementations, to support sending an indication of a communication signature, the communication manager 720 can be configured as or otherwise support means for sending an indication of a time domain code sequence for a passive wireless device, wherein the communication signature includes the time domain code sequence for the passive wireless device.

[0159] In some embodiments, to support sending a message according to a communication signature, the communication manager 720 may be configured as or otherwise support a component for sending a set of multiple repetitions of the message, wherein a time domain code sequence is associated with an element sequence, and wherein corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the message.

[0160] In some implementations, the time domain code sequence is a superimposed orthogonal code (OCC) sequence, a non-OCC sequence, or an asynchronous code sequence. In some implementations, the time domain code sequence is applied for each bit, each group of bits, or each response from a passive wireless device.

[0161] In some implementations, to support sending an indication of a communication signature including a power scaling factor for the passive wireless device, the communication manager 720 can be configured as or otherwise support means for sending an indication of a power scaling factor for the passive wireless device.

[0162] In some implementations, the power scaling factor is associated with a first priority or a first quality of service (QoS) associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0163] In some implementations, to support sending an indication of a communication signature, the communication manager 720 may be configured as or otherwise support means for sending an indication of a bandwidth associated with the message, wherein frequency domain filtering of backscatter communications from a passive wireless device is associated with the indication of the bandwidth.

[0164] In some embodiments, to support sending an indication of a communication signature, the communication manager 720 may be configured as or otherwise support a component for sending an indication of a power scaling factor for a source device, wherein the communication signature includes a power scaling factor for the source device, and wherein the power scaling factor for the source device is used based on one or more other wireless devices that use the same subchannel as used by the source device and the reader device.

[0165] In some embodiments, the power scaling factor of the source device is associated with a sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0166] In some implementations, the communication manager 720 can be configured as or otherwise support means for measuring whether the first set of subchannels is occupied based on energy detection measurements at the reader device. In some implementations, the communication manager 720 can be configured as or otherwise support means for selecting subchannels for backscatter communication from the source device to the reader device via the passive wireless device from a second set of subchannels, wherein the second set of subchannels is associated with the first set of subchannels based on a mapping relationship between occupied subchannels and available subchannels.

[0167] In some implementations, the communication manager 720 may be configured to perform various operations (such as receiving, monitoring, transmitting) using or otherwise cooperating with the transceiver 715, one or more antennas 725, or any combination thereof. Although the communication manager 720 is illustrated as a component of the transceiver 715, in some implementations, one or more functions described with reference to the communication manager 720 may be supported or performed by the transceiver 715, the processor 740, the memory 730, the code 735, or any combination thereof. For example, the code 735 may include instructions that are executable by the processor 740 to cause the device 705 to perform various aspects of the interference reduction techniques between passive wireless devices as described herein, or the processor 740 and the memory 730 may be otherwise configured to perform or support such operations.

[0168] Figure 8 A block diagram 800 of an example device 805 supporting interference reduction techniques between passive wireless devices is shown. The device 805 may communicate with one or more network entities (such as one or more components of one or more network entities 105), one or more UEs 115, or any combination thereof, which may include communication through one or more wired interfaces, through one or more wireless interfaces, or any combination thereof. The device 805 may include components that support output and acquisition communications, such as a communication manager 820, a transceiver 810, an antenna 815, a memory 825, code 830, and a processor 835. These components may be in electronic communication or otherwise coupled (such as operatively, communicatively, functionally, electronically, electrically) via one or more buses (such as bus 840).

[0169] As described herein, the transceiver 810 may support bidirectional communication via a wired link, a wireless link, or both. In some implementations, the transceiver 810 may include a wired transceiver and may communicate bidirectionally with another wired transceiver. Additionally or alternatively, in some implementations, the transceiver 810 may include a wireless transceiver and may communicate bidirectionally with another wireless transceiver. In some implementations, the device 805 may include one or more antennas 815, which may be capable of (such as concurrently) sending or receiving wireless transmissions. The transceiver 810 may also include a modem for modulating a signal, for providing a modulated signal for transmission (such as through one or more antennas 815, through a wired transmitter), for receiving a modulated signal (such as from one or more antennas 815, from a wired receiver), and for demodulating a signal.

[0170] In some implementations, the transceiver 810 may include one or more interfaces, such as one or more interfaces coupled to one or more antennas 815 configured to support various receiving or obtaining operations, or one or more interfaces coupled to one or more antennas 815 configured to support various transmitting operations or output operations, or a combination thereof. In some implementations, the transceiver 810 may include or be configured to be coupled to one or more processors or memory components that are operable to: perform or support operations based on received or obtained information or signals; or generate information or other signals for transmission or other output, or any combination thereof. In some implementations, the transceiver 810, or the transceiver 810 and one or more antennas 815, or the transceiver 810 and one or more antennas 815 and one or more processors or memory components (such as a processor 835, or a memory 825, or both) may be included in a chip or chip component installed in the device 805. In some implementations, the transceiver may be operable to support communications via one or more communication links, such as communication link 125 , backhaul communication link 120 , midhaul communication link 162 , and fronthaul communication link 168 .

[0171] The memory 825 may include RAM and ROM. The memory 825 may store computer-readable, computer-executable code 830 including instructions that, when executed by the processor 835, cause the device 805 to perform various functions described herein. The code 830 may be stored in a non-transitory computer-readable medium such as a system memory or another type of memory. In some implementations, the code 830 may not be directly executable by the processor 835, but may cause a computer (such as when compiled and executed) to perform the functions described herein. In some implementations, the memory 825 may include, among other things, a BIOS that may control basic hardware or software operations, such as interaction with peripheral components or devices.

[0172] The processor 835 may include an intelligent hardware device (such as a general-purpose processor, a DSP, an ASIC, a CPU, an FPGA, a microcontroller, a programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof). In some specific implementations, the processor 835 may be configured to operate a memory array using a memory controller. In some specific implementations, the memory controller may be integrated into the processor 835. The processor 835 may be configured to execute computer-readable instructions stored in a memory (such as a memory 825) to enable the device 805 to perform various functions (such as functions or tasks that support interference reduction techniques between passive wireless devices). For example, the device 805 or a component of the device 805 may include a processor 835 and a memory 825 coupled to the processor 835, and the processor 835 and the memory 825 are configured to perform various functions described herein. The processor 835 may be an example of a cloud computing platform (such as one or more physical nodes and supporting software such as an operating system, a virtual machine, or a container instance), which may host functions (such as by executing code 830) to perform the functions of the device 805. The processor 835 can be any suitable processor or processors capable of executing scripts or instructions of one or more software programs stored in the device 805, such as within the memory 825. In some implementations, the processor 835 can be a component of a processing system.

[0173] A processing system may generally refer to a system or a series of machines or components that receive inputs and process these inputs to produce a set of outputs (which may be passed to other systems or components (e.g., device 805)). For example, the processing system of device 805 may refer to a system including various other components or subcomponents of device 805, such as processor 835, or transceiver 810, or communication manager 820, or other components or combinations of components of device 805. The processing system of device 805 may interface with other components of device 805, and may process information (such as input or signals) received from other components or output information to other components. For example, a chip or modem of device 805 may include a processing system and one or more interfaces for outputting information or for obtaining information or both. The one or more interfaces may be implemented as or otherwise include a first interface configured to output information and a second interface configured to obtain information, or the same interface configured to output information and obtain information, as well as other specific implementations.

[0174] In some implementations, the one or more interfaces may refer to an interface between a processing system of a chip or modem and a transmitter, so that the device 805 can send information output from the chip or modem. Additionally or alternatively, in some implementations, the one or more interfaces may refer to an interface between a processing system of a chip or modem and a receiver, so that the device 805 can obtain information or signal input, and the information can be passed to the processing system. Those of ordinary skill in the art will readily recognize that the first interface may also obtain information or signal input, and the second interface may also output information or signal output.

[0175] In some implementations, the bus 840 may support communications of a protocol layer (such as within a protocol layer) of a protocol stack. In some implementations, the bus 840 may support communications associated with a logical channel of a protocol stack (such as between protocol layers of a protocol stack), which may include communications performed within a component of the device 805, or communications performed between different components of the device 805 that may be co-located or located in different locations (such as where the device 805 may refer to a system in which one or more of the communication manager 820, transceiver 810, memory 825, code 830, and processor 835 may be located in one of these different components or divided between different components).

[0176] In some implementations, the communication manager 820 can manage aspects of communications with the core network 130, such as via one or more wired or wireless backhaul links. For example, the communication manager 820 can manage the delivery of data communications for client devices, such as one or more UEs 115. In some implementations, the communication manager 820 can manage communications with other network entities 105 and can include a controller or scheduler for controlling communications with the UE 115 in collaboration with the other network entities 105. In some implementations, the communication manager 820 can support an X2 interface within an LTE / LTE-A wireless communication network technology to provide communications between network entities 105.

[0177] The communication manager 820 may support wireless communications at a passive wireless device according to examples as disclosed herein. For example, the communication manager 820 may be configured as or otherwise support a component for receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communications from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 820 may be configured as or otherwise support a component for receiving a first message from a source device. The communication manager 820 may be configured as or otherwise support a component for sending a second message to a reader device via backscatter of the first message and according to the communication signature.

[0178] Additionally or alternatively, the communication manager 820 may support wireless communications at the reader device according to examples as disclosed herein. For example, the communication manager 820 may be configured as or otherwise support means for receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 820 may be configured as or otherwise support means for receiving a message via backscatter from a passive wireless device according to the communication signature.

[0179] Additionally or alternatively, the communication manager 820 may support wireless communications at the source device according to examples as disclosed herein. For example, the communication manager 820 may be configured as or otherwise support means for sending an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from the source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for backscatter communications. The communication manager 820 may be configured as or otherwise support means for sending a message to the reader device via backscatter from the passive wireless device according to the communication signature.

[0180] In some implementations, the communication manager 820 may be configured to perform various operations (such as receiving, obtaining, monitoring, outputting, transmitting) using or otherwise cooperating with the transceiver 810, one or more antennas 815 (such as where applicable), or any combination thereof. Although the communication manager 820 is illustrated as a separate component, in some implementations, one or more functions described with reference to the communication manager 820 may be supported or performed by the transceiver 810, the processor 835, the memory 825, the code 830, or any combination thereof. For example, the code 830 may include instructions that are executable by the processor 835 to cause the device 805 to perform various aspects of the interference reduction techniques between passive wireless devices as described herein, or the processor 835 and the memory 825 may be otherwise configured to perform or support such operations.

[0181] Fig. 9 1 shows a flowchart illustrating a method 900 for supporting interference reduction techniques between passive wireless devices. The operations of the method 900 may be implemented by a UE or a network entity or a component thereof as described herein. For example, the operations of the method 900 may be implemented by a UE or a network entity or a component thereof as described herein. Figures 1 to 8The described UE 115 or network entity may be performed. In some specific implementations, the UE or network entity may execute an instruction set to control the functional elements of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform various aspects of the described functions.

[0182] At 905, the method may include receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication. The operations of 905 may be performed according to examples as disclosed herein.

[0183] At 910, the method may include receiving a first message from a source device. The operations of 910 may be performed according to examples as disclosed herein.

[0184] At 915, the method may include sending a second message to the reader device via backscatter of the first message and in accordance with the communication signature. The operations of 915 may be performed in accordance with examples as disclosed herein.

[0185] Fig.10 1 is a flowchart illustrating a method 1000 for supporting interference reduction techniques between passive wireless devices. The operations of the method 1000 may be implemented by a UE or a network entity or a component thereof as described herein. For example, the operations of the method 1000 may be implemented by a UE or a network entity or a component thereof as described herein. Figures 1 to 8 The described UE 115 or network entity may be performed. In some specific implementations, the UE or network entity may execute an instruction set to control the functional elements of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform various aspects of the described functions.

[0186] At 1005, the method may include receiving an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication. The operations of 1005 may be performed according to examples as disclosed herein.

[0187] At 1010, the method may include receiving a message via backscatter from a passive wireless device according to the communication signature. The operations of 1010 may be performed according to examples as disclosed herein.

[0188] Fig.11 1 shows a flowchart illustrating a method 1100 for supporting interference reduction techniques between passive wireless devices. The operations of the method 1100 may be implemented by a UE or a network entity or a component thereof as described herein. For example, the operations of the method 1100 may be implemented by a UE or a network entity or a component thereof as described herein. Figures 1 to 8 The described UE 115 or network entity may be performed. In some specific implementations, the UE or network entity may execute an instruction set to control the functional elements of the UE or network entity to perform the described functions. Additionally or alternatively, the UE or network entity may use dedicated hardware to perform various aspects of the described functions.

[0189] At 1105, the method may include sending an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communication from a source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication. The operations of 1105 may be performed according to examples as disclosed herein.

[0190] At 1110, the method may include sending a message to a reader device via backscatter from the passive wireless device according to the communication signature. The operations of 1110 may be performed according to examples as disclosed herein.

[0191] The following provides an overview of some aspects of the disclosure:

[0192] Aspect 1: A method for wireless communication at a passive wireless device, the method comprising: receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; receiving a first message from the source device; and sending a second message to the reader device via backscatter of the first message and based on the communication signature.

[0193] Aspect 2: The method according to aspect 1 further comprises: sending an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0194] Aspect 3: The method according to any one of aspects 1 to 2, wherein receiving the indication of the communication signature comprises: receiving an indication of a time domain code sequence, wherein the communication signature comprises the time domain code sequence.

[0195] Aspect 4: The method according to aspect 3, wherein sending the second message via the backscatter of the first message and according to the communication signature comprises: applying the time domain code sequence to a set of multiple repetitions of the first message.

[0196] Aspect 5: The method according to aspect 4, wherein the time domain code sequence is associated with an element sequence, and corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the first message.

[0197] Aspect 6: The method according to any one of Aspects 4 to 5, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence or an asynchronous code sequence.

[0198] Aspect 7: The method according to any one of aspects 4 to 6, wherein the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0199] Aspect 8: The method according to any one of aspects 1 to 7, wherein receiving the indication of the communication signature includes: receiving an indication of a power scaling factor, wherein the communication signature includes the power scaling factor.

[0200] Aspect 9: The method according to aspect 8, wherein sending the second message via the backscatter of the first message and according to the communication signature includes: applying the power scaling factor to the second message, wherein the communication signature includes the power scaling factor.

[0201] Aspect 10: The method according to aspect 9, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the first message.

[0202] Aspect 11: According to the method described in any one of Aspects 1 to 10, the method also includes: receiving an indication of a bandwidth associated with the first message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth.

[0203] Aspect 12: According to the method according to Aspect 11, the method also includes: performing energy harvesting using first RF energy received within the bandwidth associated with the first message and using second RF energy received outside the bandwidth associated with the first message; and filtering the second RF energy received outside the bandwidth associated with the first message to concentrate the backscatter of the first message to the bandwidth associated with the first message.

[0204] Aspect 13: A method according to any one of Aspects 1 to 12, wherein the first message corresponds to a first radio wave associated with a first set of bits, and the second message corresponds to a second radio wave associated with a second set of bits, and the backscattering performed by the passive wireless device is associated with amplitude shift keying modulation of the first set of bits using the second set of bits via selective reflection performed by the passive wireless device.

[0205] Aspect 14: A method for wireless communication at a reader device, the method comprising: receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and receiving a message via backscatter from the passive wireless device based on the communication signature.

[0206] Aspect 15: The method according to aspect 14, wherein receiving the indication of the communication signature includes: receiving an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0207] Aspect 16: A method according to Aspect 15, wherein receiving the message via the backscatter from the passive wireless device and according to the communication signature includes: receiving radio frequency signaling associated with a set of multiple repetitions of a message set, the set of multiple repetitions of the message set including a corresponding set of multiple repetitions for each message in the message set, wherein the message set includes the message; and extracting the message from the radio frequency signaling according to the time domain code sequence.

[0208] Aspect 17: A method according to Aspect 16, wherein extracting the message from the RF signaling comprises: multiplying each repetition in the set of multiple repetitions of the message set with the conjugate of the time domain code sequence to obtain a set of multiple products; and adding the sets of multiple products to obtain the message.

[0209] Aspect 18: The method according to any one of aspects 16 to 17, wherein each message in the message set is associated with reflected signaling from a different passive reflective device, and each passive wireless device is associated with a different time domain code sequence.

[0210] Aspect 19: A method according to any one of Aspects 16 to 18, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits or each response from the passive wireless device.

[0211] Aspect 20: A method according to any one of Aspects 14 to 19, wherein receiving the indication of the communication signature includes: receiving an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device.

[0212] Aspect 21: A method according to Aspect 20, wherein receiving the message via the backscatter from the passive wireless device and according to the communication signature includes: receiving radio frequency signaling associated with a message set, wherein the message set includes the message; and extracting the message from the radio frequency signaling according to a continuous elimination technique associated with the power scaling factor.

[0213] Aspect 22: The method according to aspect 21, wherein each message in the message set is associated with reflected signaling from a different passive reflective device, and each passive wireless device is associated with a different power scaling factor.

[0214] Aspect 23: A method according to any one of Aspects 21 to 22, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0215] Aspect 24: A method according to any one of Aspects 14 to 23, wherein receiving the indication of the communication signature includes: receiving an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device.

[0216] Aspect 25: A method according to Aspect 24, wherein the power scaling factor of the source device is associated with the sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0217] Aspect 26: According to the method described in any one of Aspects 14 to 25, the method further includes: measuring whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and selecting a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0218] Aspect 27: A method for wireless communication at a source device, the method comprising: sending an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and sending a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0219] Aspect 28: The method according to aspect 27, the method also includes: receiving an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0220] Aspect 29: A method according to any one of Aspects 27 to 28, wherein sending the indication of the communication signature includes: sending an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0221] Aspect 30: A method according to Aspect 29, wherein sending the message according to the communication signature includes: sending a set of multiple repetitions of the message, wherein the time domain code sequence is associated with an element sequence, and wherein the corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the message.

[0222] Aspect 31: A method according to any one of Aspects 29 to 30, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits or each response from the passive wireless device.

[0223] Aspect 32: A method according to any one of Aspects 27 to 31, wherein sending the indication of the communication signature includes: sending an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device.

[0224] Aspect 33: The method according to Aspect 32, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0225] Aspect 34: A method according to any one of Aspects 27 to 33, wherein sending the indication of the communication signature includes: sending an indication of a bandwidth associated with the message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth.

[0226] Aspect 35: A method according to any one of Aspects 27 to 34, wherein sending the indication of the communication signature includes: sending an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device.

[0227] Aspect 36: A method according to Aspect 35, wherein the power scaling factor of the source device is associated with the sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0228] Aspect 37: According to the method described in any one of Aspects 27 to 36, the method further includes: measuring whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and selecting a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0229] Aspect 38: An apparatus for wireless communication at a passive wireless device, the apparatus comprising: one or more interfaces, the one or more interfaces being configured to: obtain an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; obtain a first message from the source device; and output a second message to the reader device via backscatter of the first message and based on the communication signature.

[0230] Aspect 39: An apparatus according to Aspect 38, wherein the one or more interfaces are further configured to: output an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0231] Aspect 40: An apparatus according to any one of Aspects 38 to 39, wherein, in order to obtain the indication of the communication signature, the one or more interfaces are further configured to: obtain an indication of a time domain code sequence, wherein the communication signature includes the time domain code sequence.

[0232] Aspect 41: An apparatus according to Aspect 40, wherein the apparatus further includes a processing system, wherein, in order to output the second message via the backscatter of the first message and according to the communication signature, the processing system is configured to: apply the time domain code sequence to a set of multiple repetitions of the first message, wherein the time domain code sequence is associated with an element sequence, and wherein the corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the first message.

[0233] Aspect 42: The apparatus according to aspect 41, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0234] Aspect 43: An apparatus according to any one of Aspects 38 to 42, wherein, in order to obtain the indication of the communication signature, the one or more interfaces are further configured to: obtain an indication of a power scaling factor, wherein the communication signature includes the power scaling factor.

[0235] Aspect 44: An apparatus according to Aspect 43, wherein the apparatus further includes a processing system, wherein, in order to output the second message via the backscatter of the first message and according to the communication signature, the processing system is configured to: apply the power scaling factor to the second message, wherein the communication signature includes the power scaling factor, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the first message.

[0236] Aspect 45: An apparatus according to any one of Aspects 38 to 44, wherein: the one or more interfaces are further configured to: obtain an indication of a bandwidth associated with the first message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth; and the processing system is configured to: perform energy harvesting using first RF energy received within the bandwidth associated with the first message and using second RF energy received outside the bandwidth associated with the first message; and filter the second RF energy received outside the bandwidth associated with the first message to concentrate the backscatter of the first message to the bandwidth associated with the first message.

[0237] Aspect 46: An apparatus according to any one of Aspects 38 to 45, wherein: the first message corresponds to a first radio wave associated with a first bit set, and the second message corresponds to a second radio wave associated with a second bit set; and the backscattering performed by the passive wireless device is associated with amplitude shift keying modulation of the first bit set using the second bit set via selective reflection performed by the passive wireless device.

[0238] Aspect 47: An apparatus for wireless communication at a reader device, the apparatus comprising: one or more interfaces, the one or more interfaces being configured to: obtain an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and obtain a message via backscatter from the passive wireless device based on the communication signature.

[0239] Aspect 48: An apparatus according to Aspect 47, wherein, in order to obtain the indication of the communication signature, the one or more interfaces are further configured to: obtain an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0240] Aspect 49: An apparatus according to Aspect 48, wherein, in order to obtain the message via the backscatter from the passive wireless device and based on the communication signature, the one or more interfaces are further configured to: obtain radio frequency signaling associated with a set of multiple repetitions of a message set, the set of multiple repetitions of the message set including a corresponding set of multiple repetitions for each message in the message set, wherein the message set includes the message; and extract the message from the radio frequency signaling based on the time domain code sequence.

[0241] Aspect 50: An apparatus according to Aspect 49, wherein the apparatus further comprises a processing system, wherein, in order to extract the message from the radio frequency signaling, the processing system is configured to: multiply each repetition in the set of multiple repetitions of the message set by the conjugate of the time domain code sequence to obtain a set of multiple products; and add the sets of multiple products to obtain the message.

[0242] Aspect 51: An apparatus according to any one of Aspects 49 to 50, wherein each message in the message set is associated with reflected signaling from a different passive reflection device, and each passive wireless device is associated with a different time domain code sequence, and the time domain code sequence is an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0243] Aspect 52: An apparatus according to any one of Aspects 47 to 51, wherein, in order to obtain the indication of the communication signature, the one or more interfaces are further configured to: obtain an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device.

[0244] Aspect 53: An apparatus according to Aspect 52, wherein, in order to obtain the message via the backscatter from the passive wireless device and based on the communication signature, the one or more interfaces are further configured to: obtain radio frequency signaling associated with a message set, wherein the message set includes the message, wherein each message in the message set is associated with reflected signaling from different passive reflection devices, and wherein each passive wireless device is associated with a different power scaling factor; and extract the message from the radio frequency signaling based on a continuous elimination technique associated with the power scaling factor.

[0245] Aspect 54: The apparatus according to Aspect 53, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0246] Aspect 55: An apparatus according to any one of Aspects 47 to 54, wherein, in order to obtain the indication of the communication signature, the one or more interfaces are further configured to: obtain an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device, wherein the power scaling factor of the source device is associated with the subchannel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0247] Aspect 56: An apparatus according to any one of Aspects 47 to 55, wherein the apparatus further includes a processing system configured to: measure whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and select a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0248] Aspect 57: An apparatus for wireless communication at a source device, the apparatus comprising: one or more interfaces, the one or more interfaces being configured to: output an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and output a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0249] Aspect 58: An apparatus according to Aspect 57, wherein the one or more interfaces are further configured to: obtain an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0250] Aspect 59: An apparatus according to any one of Aspects 57 to 58, wherein, in order to output the indication of the communication signature, the one or more interfaces are further configured to: output an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0251] Aspect 60: An apparatus according to Aspect 59, wherein, in order to output the message according to the communication signature, the one or more interfaces are further configured to: output a set of multiple repetitions of the message, wherein the time domain code sequence is associated with an element sequence, and wherein the corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the message.

[0252] Aspect 61: An apparatus according to any one of Aspects 59 to 60, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0253] Aspect 62: An apparatus according to any one of Aspects 57 to 61, wherein, in order to output the indication of the communication signature, the one or more interfaces are further configured to: output an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0254] Aspect 63: An apparatus according to any one of Aspects 57 to 62, wherein, in order to output the indication of the communication signature, the one or more interfaces are further configured to: output an indication of a bandwidth associated with the message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth.

[0255] Aspect 64: An apparatus according to any one of Aspects 57 to 63, wherein, in order to output the indication of the communication signature, the one or more interfaces are further configured to: output an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device.

[0256] Aspect 65: An apparatus according to Aspect 64, wherein the power scaling factor of the source device is associated with the sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0257] Aspect 66: An apparatus according to any one of Aspects 57 to 65, wherein the apparatus further includes a processing system, wherein the processing system is configured to: measure whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and select a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0258] Aspect 67: An apparatus for wireless communication at a passive wireless device, the apparatus comprising: a component for receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; a component for receiving a first message from the source device; and a component for sending a second message to the reader device via backscatter of the first message and based on the communication signature.

[0259] Aspect 68: The apparatus according to Aspect 67 further includes: a component for sending an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0260] Aspect 69: An apparatus according to any one of Aspects 67 to 68, wherein the component for receiving the indication of the communication signature includes: a component for receiving an indication of a time domain code sequence, wherein the communication signature includes the time domain code sequence.

[0261] Aspect 70: The apparatus according to Aspect 69, wherein the means for sending the second message via the backscatter of the first message and according to the communication signature includes: means for applying the time domain code sequence to a set of multiple repetitions of the first message.

[0262] Aspect 71: The apparatus according to Aspect 70, wherein the time domain code sequence is associated with an element sequence, and corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the first message.

[0263] Aspect 72: An apparatus according to any one of Aspects 70 to 71, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence or an asynchronous code sequence.

[0264] Aspect 73: The apparatus according to any one of aspects 70 to 72, wherein the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0265] Aspect 74: An apparatus according to any one of Aspects 67 to 73, wherein the means for receiving the indication of the communication signature includes: means for receiving an indication of a power scaling factor, wherein the communication signature includes the power scaling factor.

[0266] Aspect 75: An apparatus according to Aspect 74, wherein the means for sending the second message via the backscatter of the first message and according to the communication signature includes: a means for applying the power scaling factor to the second message, wherein the communication signature includes the power scaling factor.

[0267] Aspect 76: The apparatus according to Aspect 75, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the first message.

[0268] Aspect 77: An apparatus according to any one of Aspects 67 to 76, the apparatus further comprising: a component for receiving an indication of a bandwidth associated with the first message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth.

[0269] Aspect 78: According to the device of Aspect 77, the device also includes: a component for performing energy harvesting using first radio frequency energy received within the bandwidth associated with the first message and using second radio frequency energy received outside the bandwidth associated with the first message; and a component for filtering the second radio frequency energy received outside the bandwidth associated with the first message to concentrate the backscatter of the first message to the bandwidth associated with the first message.

[0270] Aspect 79: An apparatus according to any one of Aspects 67 to 78, wherein the first message corresponds to a first radio wave associated with a first set of bits, and the second message corresponds to a second radio wave associated with a second set of bits, and the backscattering performed by the passive wireless device is associated with amplitude shift keying modulation of the first set of bits using the second set of bits via selective reflection performed by the passive wireless device.

[0271] Aspect 80: An apparatus for wireless communication at a reader device, the apparatus comprising: a component for receiving an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and a component for receiving a message via backscatter from the passive wireless device based on the communication signature.

[0272] Aspect 81: An apparatus according to Aspect 80, wherein the component for receiving the indication of the communication signature includes: a component for receiving an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0273] Aspect 82: An apparatus according to Aspect 81, wherein the component for receiving the message via the backscatter from the passive wireless device and according to the communication signature includes: a component for receiving radio frequency signaling associated with a set of multiple repetitions of a message set, the set of multiple repetitions of the message set including a corresponding set of multiple repetitions for each message in the message set, wherein the message set includes the message; and a component for extracting the message from the radio frequency signaling according to the time domain code sequence.

[0274] Aspect 83: An apparatus according to Aspect 82, wherein the component for extracting the message from the radio frequency signaling includes: a component for multiplying each repetition in the set of multiple repetitions of the message set with the conjugate of the time domain code sequence to obtain a set of multiple products; and a component for adding the set of multiple products to obtain the message.

[0275] Aspect 84: An apparatus according to any one of aspects 82 to 83, wherein each message in the set of messages is associated with reflected signaling from a different passive reflective device, and each passive wireless device is associated with a different time domain code sequence.

[0276] Aspect 85: An apparatus according to any one of Aspects 82 to 84, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0277] Aspect 86: An apparatus according to any one of Aspects 80 to 85, wherein the component for receiving the indication of the communication signature includes: a component for receiving an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device.

[0278] Aspect 87: An apparatus according to Aspect 86, wherein the component for receiving the message via the backscatter from the passive wireless device and based on the communication signature includes: a component for receiving radio frequency signaling associated with a message set, wherein the message set includes the message; and a component for extracting the message from the radio frequency signaling based on a continuous elimination technique associated with the power scaling factor.

[0279] Aspect 88: The apparatus of aspect 87, wherein each message in the set of messages is associated with reflected signaling from a different passive reflective device, and each passive wireless device is associated with a different power scaling factor.

[0280] Aspect 89: An apparatus according to any one of Aspects 87 to 88, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0281] Aspect 90: An apparatus according to any one of Aspects 80 to 89, wherein the component for receiving the indication of the communication signature includes: a component for receiving an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device.

[0282] Aspect 91: An apparatus according to Aspect 90, wherein the power scaling factor of the source device is associated with the sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0283] Aspect 92: An apparatus according to any one of Aspects 80 to 91, the apparatus further comprising: a component for measuring whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and a component for selecting a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0284] Aspect 93: An apparatus for wireless communication at a source device, the apparatus comprising: a component for sending an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and a component for sending a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0285] Aspect 94: The apparatus according to Aspect 93 further includes: a component for receiving an indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication, wherein the communication signature is associated with the capability of the passive wireless device.

[0286] Aspect 95: An apparatus according to any one of Aspects 93 to 94, wherein the component for sending the indication of the communication signature includes: a component for sending an indication of a time domain code sequence of the passive wireless device, wherein the communication signature includes the time domain code sequence of the passive wireless device.

[0287] Aspect 96: An apparatus according to Aspect 95, wherein the component for sending the message according to the communication signature includes: a component for sending a set of multiple repetitions of the message, wherein the time domain code sequence is associated with an element sequence, and wherein the corresponding elements in the element sequence are applied to each consecutive repetition in the set of multiple repetitions of the message.

[0288] Aspect 97: An apparatus according to any one of Aspects 95 to 96, wherein the time domain code sequence is an OCC sequence, a non-OCC sequence, or an asynchronous code sequence, and the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

[0289] Aspect 98: An apparatus according to any one of Aspects 93 to 97, wherein the component for sending the indication of the communication signature includes: a component for sending an indication of a power scaling factor of the passive wireless device, wherein the communication signature includes the power scaling factor of the passive wireless device.

[0290] Aspect 99: An apparatus according to Aspect 98, wherein the power scaling factor is associated with a first priority or a first QoS associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the message.

[0291] Aspect 100: An apparatus according to any one of Aspects 93 to 99, wherein the component for sending the indication of the communication signature includes: a component for sending an indication of a bandwidth associated with the message, wherein frequency domain filtering of the backscatter communication from the passive wireless device is associated with the indication of the bandwidth.

[0292] Aspect 101: An apparatus according to any one of Aspects 93 to 100, wherein the component for sending the indication of the communication signature includes: a component for sending an indication of a power scaling factor of the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, and the one or more other wireless devices use the same subchannel as the subchannel used by the source device and the reader device.

[0293] Aspect 102: An apparatus according to Aspect 101, wherein the power scaling factor of the source device is associated with the sub-channel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

[0294] Aspect 103: An apparatus according to any one of Aspects 93 to 102, the apparatus further comprising: a component for measuring whether a first subchannel set is occupied based on an energy detection measurement at the reader device; and a component for selecting a subchannel from a second subchannel set for the backscatter communication from the source device to the reader device via the passive wireless device, wherein the second subchannel set is associated with the first subchannel set based on a mapping relationship between occupied subchannels and available subchannels.

[0295] Aspect 104: A non-transitory computer-readable medium storing code for wireless communication at a passive wireless device, the code comprising instructions executable by a processor to: receive an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; receive a first message from the source device; and send a second message to the reader device via backscatter of the first message and based on the communication signature.

[0296] Aspect 105: The non-transitory computer-readable medium of aspect 104, wherein the instructions for receiving the indication of the communication signature are executable by the processor to: receive an indication of a time domain code sequence, wherein the communication signature includes the time domain code sequence.

[0297] Aspect 106: A non-transitory computer-readable medium storing code for wireless communication at a reader device, the code comprising instructions executable by a processor to: receive an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and receive a message via backscatter from the passive wireless device based on the communication signature.

[0298] Aspect 107: A non-transitory computer-readable medium storing code for wireless communication at a source device, the code comprising instructions executable by a processor to: send an indication of a communication signature in a communication signature set, the communication signature being specific to backscatter communication from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communication; and send a message to the reader device via backscatter from the passive wireless device based on the communication signature.

[0299] As used herein, the term "determine" or "determine" encompasses a wide variety of actions, and thus, "determine" may include calculating, computing, processing, deriving, investigating, searching (such as via searching in a table, database, or other data structure), reasoning, ascertaining, and similar actions. Additionally, "determine" may include receiving (such as receiving information), accessing (such as accessing data stored in a memory), and similar actions. Additionally, "determine" may include parsing, selecting, choosing, establishing, and other such similar actions.

[0300] As used herein, a phrase referring to "at least one of" a list of items refers to any combination of those items (including single members). As an example, "at least one of a, b, or c" is intended to cover: a, b, c, ab, ac, bc, and abc.

[0301] The various illustrative logical components, logic blocks, modules, circuits, and algorithmic processes described in conjunction with the specific implementations disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. The interchangeability of hardware and software has been generally described in terms of functionality and is illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented using hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0302] The hardware and data processing apparatus for implementing the various exemplary logic components, logic blocks, modules and circuits described in conjunction with the various aspects disclosed herein may be implemented or executed using a general purpose single-chip or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic component, a discrete hardware component, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or any processor, controller, microcontroller or state machine. A processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In some specific implementations, specific processes and methods may be performed by circuits specific to a given function.

[0303] In one or more aspects, the functions described may be implemented using hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents, or in any combination thereof. Specific implementations of the subject matter described in this specification may also be implemented as one or more computer programs, such as one or more modules of computer program instructions encoded on computer storage media for execution by a data processing device or for controlling the operation of a data processing device.

[0304] If implemented in software, the function can be stored or sent using one or more instructions or codes of a computer-readable medium. The process of the method or algorithm disclosed herein can be implemented in a processor executable software module that can reside on a computer-readable medium. Computer-readable media include both computer storage media and communication media, and the communication media include any medium that can be implemented to transfer a computer program from one location to another. The storage medium can be any available medium accessible to a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage devices, magnetic disk storage devices or other magnetic storage devices, or any other medium that can be used to store the desired program code in the form of an instruction or data structure and can be accessed by a computer. In addition, any connection can be appropriately referred to as a computer-readable medium. As used herein, disks and optical disks include compact disks (CDs), laser optical disks, optical optical disks, digital versatile disks (DVDs), floppy disks, and blue-ray disks. Disks can reproduce data magnetically, and optical disks can reproduce data optically with lasers. The above combination should also be included in the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine-readable medium and a computer-readable medium, which may be incorporated into a computer program product.

[0305] Various modifications to the specific implementations described in this disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other specific implementations without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the specific implementations shown herein, but should be granted the widest scope consistent with the disclosure, the principles and features disclosed herein.

[0306] Additionally, one of ordinary skill in the art will readily recognize that the terms "upper" and "lower" are sometimes used for ease of describing the drawings and indicate relative positions corresponding to the orientation of the drawings on a correctly oriented page, and may not reflect the correct orientation of any device as implemented.

[0307] Certain features described in this specification in the context of a single implementation may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations individually or in any suitable subcombination. Furthermore, while features may be described above as functioning in some combination and even initially claimed as such, one or more features from a claimed combination may be removed from the combination, and a claimed combination may involve subcombinations or variations of subcombinations.

[0308] Similarly, although the operations are depicted in a specific order in the figure, this should not be understood as requiring such operations to be performed in the specific order shown or in a sequential order, or to perform all the illustrated operations to achieve the desired result. Further, the accompanying drawings can schematically depict one or more example processes in the form of a flow chart. However, other operations not depicted can be incorporated into the schematically illustrated example process. For example, one or more additional operations can be performed before, after, at the same time, or between any operations in the illustrated operations. In some environments, multitasking and parallel processing may be advantageous. In addition, the separation of each system component in the specific implementation described above should not be understood as requiring such separation in all specific implementations, but it should be understood that the described program components and systems can usually be integrated together in a single software product, or be packaged in multiple software products. In addition, other specific implementations are within the scope of the following claims. In some specific implementations, the actions described in the claims can be performed in different orders and still achieve the desired results.

Claims

1. An apparatus for wireless communication at a passive wireless device, the apparatus comprising: One or more interfaces, the one or more interfaces being configured to: obtaining an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from a source device to a reader device via the passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communications; Obtain a first message from the source device; as well as A second message is output to the reader device via backscattering of the first message and in accordance with the communication signature.

2. The apparatus of claim 1, wherein the one or more interfaces are further configured to: An indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication is output, wherein the communication signature is associated with the capability of the passive wireless device.

3. The device according to claim 1, wherein: To obtain the indication of the communication signature, the one or more interfaces are further configured to: An indication of a time-domain code sequence is obtained, wherein the communication signature includes the time-domain code sequence.

4. The device according to claim 3, further comprising a processing system, wherein: To output the second message via the backscatter of the first message and in accordance with the communication signature, the processing system is configured to: The time-domain code sequence is applied to a plurality of repetitions of the first message, wherein the time-domain code sequence is associated with a sequence of elements, and wherein a corresponding element in the sequence of elements is applied to each consecutive repetition of the plurality of repetitions of the first message.

5. The apparatus of claim 4, wherein the time domain code sequence is a superimposed orthogonal code (OCC) sequence, a non-OCC sequence, or an asynchronous code sequence, and wherein the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

6. The device according to claim 1, wherein: To obtain the indication of the communication signature, the one or more interfaces are further configured to: An indication of a power scaling factor is obtained, wherein the communication signature includes the power scaling factor.

7. The device according to claim 6, further comprising a processing system, wherein: To output the second message via the backscatter of the first message and in accordance with the communication signature, the processing system is configured to: Applying the power scaling factor to the second message, wherein the communication signature includes the power scaling factor, wherein the power scaling factor is associated with a first priority or a first quality of service (QoS) associated with the passive wireless device, or is associated with a second priority or a second QoS associated with the first message.

8. The device according to claim 1, wherein: The one or more interfaces are further configured to: obtaining an indication of a bandwidth associated with the first message, wherein frequency domain filtering of the backscatter communications from the passive wireless device is associated with the indication of the bandwidth; and The processing system is configured to: performing energy harvesting using first radio frequency energy received within the bandwidth associated with the first message and using second radio frequency energy received outside the bandwidth associated with the first message; as well as filtering the second radio frequency energy received outside the bandwidth associated with the first message, to focus the backscatter of the first message to the bandwidth associated with the first message.

9. An apparatus for wireless communication at a reader device, the apparatus comprising: One or more interfaces, the one or more interfaces being configured to: obtaining an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from a source device to the reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communications; as well as A message is obtained via backscatter from the passive wireless device according to the communication signature.

10. The device according to claim 9, wherein: To obtain the indication of the communication signature, the one or more interfaces are further configured to: An indication of a time domain code sequence of the passive wireless device is obtained, wherein the communication signature includes the time domain code sequence of the passive wireless device.

11. The device according to claim 10, wherein: To obtain the message via the backscatter from the passive wireless device and based on the communication signature, the one or more interfaces are further configured to: obtaining radio frequency signaling associated with a plurality of repetitions of a set of messages, the plurality of repetitions of the set of messages comprising a respective plurality of repetitions for each message in the set of messages, wherein the set of messages comprises the message; and The message is extracted from the radio frequency signaling according to the time domain code sequence.

12. The apparatus according to claim 11, further comprising a processing system, wherein: In order to extract the message from the radio frequency signaling, the processing system is configured to: multiplying each of the plurality of repetitions of the message set by a conjugate of the time-domain code sequence to obtain a plurality of products; as well as The multiple products are added to obtain the message.

13. The apparatus of claim 11, wherein each message in the message set is associated with reflected signaling from a different passive reflector device, and wherein each passive wireless device is associated with a different time domain code sequence, and wherein the time domain code sequence is a superimposed orthogonal code (OCC) sequence, a non-OCC sequence, or an asynchronous code sequence, and wherein the time domain code sequence is applied for each bit, each group of bits, or each response from the passive wireless device.

14. The device according to claim 9, wherein: To obtain the indication of the communication signature, the one or more interfaces are further configured to: An indication of a power scaling factor for the passive wireless device is obtained, wherein the communication signature includes the power scaling factor for the passive wireless device.

15. The device according to claim 14, wherein: To obtain the message via the backscatter from the passive wireless device and based on the communication signature, the one or more interfaces are further configured to: obtaining radio frequency signaling associated with a set of messages, wherein the set of messages includes the messages, wherein each message in the set of messages is associated with reflected signaling from a different passive reflective device, and wherein each passive wireless device is associated with a different power scaling factor; as well as The message is extracted from the radio frequency signaling according to a successive cancellation technique associated with the power scaling factor.

16. The device according to claim 9, wherein: To obtain the indication of the communication signature, the one or more interfaces are further configured to: Obtain an indication of a power scaling factor for the source device, wherein the communication signature includes the power scaling factor of the source device, and wherein the power scaling factor of the source device is used based on one or more other wireless devices, the one or more other wireless devices using the same subchannel as used by the source device and the reader device, wherein the power scaling factor of the source device is associated with the subchannel used by the source device and the reader device, a first set of distances between the reader device and the one or more other wireless devices, a second set of distances between the passive wireless device and the one or more other wireless devices, or a transmit power used by the one or more other wireless devices, or any combination thereof.

17. An apparatus for wireless communication at a source device, the apparatus comprising: One or more interfaces, the one or more interfaces being configured to: outputting an indication of a communication signature in a set of communication signatures, the communication signature being specific to backscatter communications from the source device to a reader device via a passive wireless device, wherein the communication signature is associated with interference avoidance for the backscatter communications; as well as A message is output to the reader device via backscatter from the passive wireless device in accordance with the communication signature.

18. The apparatus of claim 17, wherein the one or more interfaces are further configured to: An indication of a capability of the passive wireless device associated with the interference avoidance for the backscatter communication is obtained, wherein the communication signature is associated with the capability of the passive wireless device.

19. The device according to claim 17, wherein: To output the indication of the communication signature, the one or more interfaces are further configured to: An indication of a time domain code sequence of the passive wireless device is output, wherein the communication signature includes the time domain code sequence of the passive wireless device.

20. The device according to claim 19, wherein To output the message according to the communication signature, the one or more interfaces are further configured to: A plurality of repetitions of the message are output, wherein the time-domain code sequence is associated with a sequence of elements, and wherein corresponding elements in the sequence of elements are applied to each consecutive repetition of the plurality of repetitions of the message.

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