Abstract: A radio-frequency identification (RFID) tag, or tag, is affixed to a particular item and stores unique identifying information about that item. It can be queried with a reader that transmits wireless signals to the tag and receive the tag's responses, which can be correlated with information in inventory records. Conventionally, when a reader stops receiving a tag's responses to these queries, the inventory records are updated to show that the tag and associated item have been removed from the inventory. But a tag can stop producing detectable response for other reasons, including being too close to other tags, so simply removing the tag and item can lead to inaccurate inventory records. Stateful inventory technology address this problem by maintaining and transitioning tags among different states, including a stale state for tags that have not been read recently, depending on when and where the tags were last read.

Abstract: Radio-frequency identification (RFID) systems use readers to query and locate passive RFID tags in stores, warehouses, and other environments. An interrogation signal emitted by an antenna array from a reader powers up the tag, which replies by modulating and backscattering incident radiation toward the reader. The antenna array in the reader detects the modulated and backscattered radiation, which is usually several of orders of magnitude weaker than the interrogation signal, as the tag's reply. Unfortunately, crosstalk between the antenna elements in the antenna array limits the reader's sensitivity, which in turn limits the range at which the reader can detect and locate tags. Increasing the pitch of the antenna array to greater than half the wavelength of the interrogation signal reduces crosstalk but introduces grating lobes that produce spurious replies. Fortunately, filtering these spurious replies yields sensitive measurements from an antenna array with a pitch large enough to suppress crosstalk.

Abstract: A communication technique for synchronizing a set of radio nodes is described. In this communication technique, the radio node arbitrates (e.g., using a precision time protocol or PTP) with the other radio nodes based on a selection technique to select a synchronization master in the set of radio nodes. This synchronization master may be selected to have a predefined performance based on a type of communication environment of the set of radio nodes. For example, the type of communication environment may include overlap between at least one of the radio nodes in the set of radio nodes and a macrocell in a cellular-telephone network, or may exclude overlap between the set of radio nodes and the macrocell. Moreover, the synchronization master may specify time, frequency, and phase synchronization for the set of radio nodes. Thus, when the synchronization master is different from the radio node, the radio node synchronizes with the synchronization master.

Abstract: A radio-frequency identification (RFID) tag reader interrogates RFID tags and detects their replies. These replies may propagate along direct or line-of-sight paths from the tags to the reader. They may also propagate along indirect or non-light-of-sight paths from the tags to the reader, e.g., by reflecting off nearby objects to the reader. As a result, the reader receives many copies of each tag's reply, with each copy arriving at a delay and angle corresponding to the path that it followed from the tag to the reader. The aggregate or combination of the detected replies is called a multipath profile or signature. Each tag/reader pair produces its own multipath profile. Moving objects near the reader and tag can change that multipath signature by introducing or removing reflections along a given path between the reader and tag. These changes can be used to determine that an object has moved, even if that object does not have an RFID tag.

Abstract: A radio node may calculate one or more performance metrics based on measured satellite signals, which are associated with a global positioning system, or wireless signals that are associated with a cellular-telephone network. Then, the radio node may determine, based on the one or more performance metrics, whether the radio node is a synchronization master in a cluster of radio nodes. When the radio node is the synchronization master, the radio node may provide information intended for a computer specifying that the radio node is the synchronization master and the one or more performance metrics. In response, the radio node may receive a synchronization request associated with another radio node in the cluster. Furthermore, the radio node may provide the synchronization information intended for the other radio node, where the synchronization information specifies time, frequency, and phase synchronization for at least the cluster.

Abstract: In order to facilitate communication in a shared-license-access band of frequencies, an electronic device (such as an electronic device that implements a spectrum allocation service) allocates, to a radio node in a set of radio nodes, at least a first channel and a second channel in unallocated channels in the shared-license-access band of frequencies. Note that the first channel and the second channel are noncontiguous in the shared-license-access band of frequencies. Then, the electronic device monitors for transmissions by a higher-priority user than the set of radio nodes in the shared-license-access band of frequencies. When the transmissions are detected in the first channel, the electronic device instructs the radio node to discontinue use of the first channel, where allocation of at least the second channel allows uninterrupted communication by the radio node in the shared-license-access band of frequencies.

Abstract: A radio node that dynamically exchanges information specifying available spectrum in a shared-license-access band of frequencies is described. During operation, the radio node may provide a first grant request to a computer, where the first grant request includes a request to reserve a first portion of the shared-license-access band of frequencies for use by the radio node. Then, the radio node may receive from the computer a grant response. When the grant response indicates that the first grant request is denied, the radio node may provide to a second radio node a first notification that the request for a first portion of the shared-license-access band of frequencies was rejected. Similarly, the radio node may receive from the second radio node a second notification that a request for a second portion of the shared-license-access band of frequencies was rejected.

Abstract: An integrated system is described. This integrated system includes: a radio node that communicates using a cellular-telephone communication protocol; and an access point that communicates using an IEEE 802.11 communication protocol. Moreover, the integrated system includes a housing between the radio node and the access point, where the housing provides mechanical coupling and electrical coupling between the radio node and the access point, and the housing provides electrical power and data to the access point from the radio node. For example, the housing may provide the electrical power and the data using a PoE cable. In some embodiments, the radio node dynamically modifies the electrical power provided to the access point or receives, from a controller, an instruction specifying the electrical power to be provided to the access point.

Abstract: A radio node may transmit a signal using a transmit power. Then, the radio node may adjust the transmit power within a range of values. The adjustment may include reducing the transmit power when a spatial received signal strength indication (RSSI) metric of the radio node is greater than a first threshold value and a coverage criterion is met. Note that the spatial RSSI metric of the radio node may correspond to a set of temporal RSSI metrics of the radio node received from neighboring radio nodes. Moreover, the coverage criterion may be that less than a portion of RSSI measurements of the radio node associated with electronic devices, which are communicatively attached with the radio node, is less than a second threshold value. Alternatively, the adjustment may include increasing the transmit power when the spatial RSSI metric is less than the first threshold value.

Abstract: An electronic device that establishes a second connection is described. After determining its location, the electronic device may provide information that specifies the location to a cellular-telephone network using a first connection to the cellular-telephone network. In response, the electronic device may receive mapping information. When the mapping information indicates that there are available channels in associated bands of frequencies at the location, the electronic device may: perform a scan of the available channels in the associated bands of frequencies; and establish the second connection with a radio node based on scan results. Alternatively, when the mapping information indicates that there are no available channels in associated frequency bands at the location, the electronic device may establish a third connection with the radio node in a licensed band of frequencies.

Abstract: In order to facilitate communication in a shared-license-access band of frequencies, an electronic device (such as an electronic device that implements a spectrum allocation service) allocates, to a radio node in a set of radio nodes, at least a first channel and a second channel in unallocated channels in the shared-license-access band of frequencies. Note that the first channel and the second channel are noncontiguous in the shared-license-access band of frequencies. Then, the electronic device monitors for transmissions by a higher-priority user than the set of radio nodes in the shared-license-access band of frequencies. When the transmissions are detected in the first channel, the electronic device instructs the radio node to discontinue use of the first channel, where allocation of at least the second channel allows uninterrupted communication by the radio node in the shared-license-access band of frequencies.

Abstract: A radio node may calculate one or more performance metrics based on measured satellite signals, which are associated with a global positioning system, or wireless signals that are associated with a cellular-telephone network. Then, the radio node may determine, based on the one or more performance metrics, whether the radio node is a synchronization master in a cluster of radio nodes. When the radio node is the synchronization master, the radio node may provide information intended for a computer specifying that the radio node is the synchronization master and the one or more performance metrics. In response, the radio node may receive a synchronization request associated with another radio node in the cluster. Furthermore, the radio node may provide the synchronization information intended for the other radio node, where the synchronization information specifies time, frequency, and phase synchronization for at least the cluster.

Abstract: A radio node may calculate one or more performance metrics based on measured satellite signals, which are associated with a global positioning system, or wireless signals that are associated with a cellular-telephone network. Then, the radio node may determine, based on the one or more performance metrics, whether the radio node is a synchronization master in a cluster of radio nodes. When the radio node is the synchronization master, the radio node may provide information intended for a computer specifying that the radio node is the synchronization master and the one or more performance metrics. In response, the radio node may receive a synchronization request associated with another radio node in the cluster. Furthermore, the radio node may provide the synchronization information intended for the other radio node, where the synchronization information specifies time, frequency, and phase synchronization for at least the cluster.

Abstract: A communication technique for synchronizing a set of radio nodes is described. In this communication technique, the radio node arbitrates (e.g., using a precision time protocol or PTP) with the other radio nodes based on a selection technique to select a synchronization master in the set of radio nodes. This synchronization master may be selected to have a predefined performance based on a type of communication environment of the set of radio nodes. For example, the type of communication environment may include overlap between at least one of the radio nodes in the set of radio nodes and a macrocell in a cellular-telephone network, or may exclude overlap between the set of radio nodes and the macrocell. Moreover, the synchronization master may specify time, frequency, and phase synchronization for the set of radio nodes. Thus, when the synchronization master is different from the radio node, the radio node synchronizes with the synchronization master.

Abstract: A radio node that dynamically exchanges information specifying available spectrum in a shared-license-access band of frequencies is described. During operation, the radio node may provide a first grant request to a computer, where the first grant request includes a request to reserve a first portion of the shared-license-access band of frequencies for use by the radio node. Then, the radio node may receive from the computer a grant response. When the grant response indicates that the first grant request is denied, the radio node may provide to a second radio node a first notification that the request for a first portion of the shared-license-access band of frequencies was rejected. Similarly, the radio node may receive from the second radio node a second notification that a request for a second portion of the shared-license-access band of frequencies was rejected.

Abstract: An integrated system is described. This integrated system includes: a radio node that communicates using a cellular-telephone communication protocol; and an access point that communicates using an IEEE 802.11 communication protocol. Moreover, the integrated system includes a housing between the radio node and the access point, where the housing provides mechanical coupling and electrical coupling between the radio node and the access point, and the housing provides electrical power and data to the access point from the radio node. For example, the housing may provide the electrical power and the data using a PoE cable. In some embodiments, the radio node dynamically modifies the electrical power provided to the access point or receives, from a controller, an instruction specifying the electrical power to be provided to the access point.

Abstract: A communication technique for synchronizing a set of radio nodes is described. In this communication technique, the radio node arbitrates (e.g., using a precision time protocol or PTP) with the other radio nodes based on a selection technique to select a synchronization master in the set of radio nodes. This synchronization master may be selected to have a predefined performance based on a type of communication environment of the set of radio nodes. For example, the type of communication environment may include overlap between at least one of the radio nodes in the set of radio nodes and a macrocell in a cellular-telephone network, or may exclude overlap between the set of radio nodes and the macrocell. Moreover, the synchronization master may specify time, frequency, and phase synchronization for the set of radio nodes. Thus, when the synchronization master is different from the radio node, the radio node synchronizes with the synchronization master.

Abstract: A radio node may transmit a signal using a transmit power. Then, the radio node may adjust the transmit power within a range of values. The adjustment may include reducing the transmit power when a spatial received signal strength indication (RSSI) metric of the radio node is greater than a first threshold value and a coverage criterion is met. Note that the spatial RSSI metric of the radio node may correspond to a set of temporal RSSI metrics of the radio node received from neighboring radio nodes. Moreover, the coverage criterion may be that less than a portion of RSSI measurements of the radio node associated with electronic devices, which are communicatively attached with the radio node, is less than a second threshold value. Alternatively, the adjustment may include increasing the transmit power when the spatial RSSI metric is less than the first threshold value.

Abstract: A radio node may transmit a signal using a transmit power. Then, the radio node may adjust the transmit power within a range of values. The adjustment may include reducing the transmit power when a spatial received signal strength indication (RSSI) metric of the radio node is greater than a first threshold value and a coverage criterion is met. Note that the spatial RSSI metric of the radio node may correspond to a set of temporal RSSI metrics of the radio node received from neighboring radio nodes. Moreover, the coverage criterion may be that less than a portion of RSSI measurements of the radio node associated with electronic devices, which are communicatively attached with the radio node, is less than a second threshold value. Alternatively, the adjustment may include increasing the transmit power when the spatial RSSI metric is less than the first threshold value.

Abstract: In order to facilitate communication in a shared-license-access band of frequencies, an electronic device (such as an electronic device that implements a spectrum allocation service) allocates, to a radio node in a set of radio nodes, at least a first channel and a second channel in unallocated channels in the shared-license-access band of frequencies. Note that the first channel and the second channel are noncontiguous in the shared-license-access band of frequencies. Then, the electronic device monitors for transmissions by a higher-priority user than the set of radio nodes in the shared-license-access band of frequencies. When the transmissions are detected in the first channel, the electronic device instructs the radio node to discontinue use of the first channel, where allocation of at least the second channel allows uninterrupted communication by the radio node in the shared-license-access band of frequencies.