Patent Description:
Communications using small-cell transceivers in wireless network systems can be affected by movement of the transceiver. In some systems, movement of even a few centimeters can cause enough of a signal impedance change to affect communication channels, for example, causing dropped calls or reducing data rates.

<CIT> discloses a coupling device including a receiving portion that receives a radio frequency signal conveying data from a transmitting device. A magnetic coupler magnetically couples the radio frequency signal to a transmission medium as a guided electromagnetic wave that is bound by an outer surface of the transmission medium.

<CIT> discloses an antenna enclosure designed to be suspended from a line such as a messenger strand which extends in a first direction between a pair of utility poles, in a similar manner to other aerial strand mounted communication system components. At least one antenna element is mounted in the enclosure. The antenna enclosure in one example is elongated in the first direction and tapers inwardly in a vertical direction between the upper and lower ends of the enclosure. Two spaced connecting brackets mounted on the upper end of the enclosure are configured for connection to spaced positions on a line to suspend the enclosure from the line.

<CIT> discloses a system for wirelessly communicating from a high speed data modem using a first radio transceiver at a first location and a second radio transceiver at a second location preferably includes: (i) a housing (containing the data modem, the first radio transceiver, a radio processor, and a power supply) connected to an outdoor supporting structure, which supports a coaxial cable carrying an RF signal and AC power; (ii) a splitter to split the RF signal from the AC power, wherein the radio processor sends a digital signal to the first radio transceiver, which sends the signal to a first antenna, and wherein the signal is provided from the first antenna to a second antenna coupled to the second radio transceiver at a user device, wherein the system communicates the signal from the second antenna to the second radio transceiver and then to a second radio processor coupled to the user device; and wherein the DC power is provided to the data modem, the first radio transceiver, and the radio processor.

In a described arrangement, a motion sensing device may be incorporated into a small cell apparatus to report movement of the cell to a central station for analysis. This may be particularly true when the cell is mounted on structures subject to movement including a mid-span installation on an outdoor cable, such as on the strand used to support wired network cabling. Such an installation may be subject to movement due to wind, other weather conditions, or nearby activity. The motion sensing device may include one or more accelerometers, a GPS receiver, optical sensors or combinations of these or others. Movement may be reported to a server for analysis and processing, including matching cell motion to call statistics. When a determination is made that movement of the small cell apparatus is causing service issues, the cell location may be stabilized or the apparatus may be remounted or moved.

Aspects of the present invention are recited by the appended claims.

The figures depict a preferred embodiment for purposes of illustration only. One skilled in the art may readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles described herein.

Cellular telephone sites are traditionally mounted on towers or buildings that provide stable platforms for the antenna structures associated with the cell site. The relatively low frequencies of the cell sites, such as <NUM>, accommodate both coverage areas in the kilometers and an inherent insensitivity to antenna movement. In more recent cellular system designs using a small cell apparatus, the combination of lower power cell transmitters along with higher frequencies into the tens of GHz and their correspondingly shorter wavelengths may result in a greater sensitivity to cell/antenna motion. This may be particularly true in the case of beam-forming technology used to steer radio energy to a particular target device.

In the following discussion, although the actual interest is in the movement of an antenna, the construction of a small cell apparatus generally involves an integral antenna, so that movement of the small cell directly corresponds to movement of its antenna. In a case where the actual transceiver may be remote from its antenna, the following teachings may be applied to the antenna itself. However, for the sake of simplicity, the former example will be used in this description.

In order to measure antenna motion, a small cell apparatus may include a motion sensing device to measure and report movement of the small cell apparatus. This movement information may be used in analyzing the effects of cell movement on call quality of service. For example, measured cell movement may be correlated to quality measurements such as dropped calls, lost packets, packet retries, or data rate.

<FIG> is an illustration of a simplified and exemplary embodiment of a small cell apparatus <NUM> showing a strand-mounting. A pole <NUM> may support multiple wired lines, including power transmission lines <NUM> and a small signal line <NUM>. Typically, a small signal line <NUM> may be mounted <NUM> (<NUM> inches) or more below the power transmission lines <NUM>. The small signal line <NUM> may include wired (landline) telephone conductors, cable TV/Internet conductors, fiber optic lines, or other signal carriers that do not represent an electrocution risk. The small signal line <NUM> may be hung from a steel cable or similar support mechanism known as a strand <NUM>. In some cases, the strand <NUM> may be encased within a jacket (not depicted) holding the associated small signal line <NUM> while in other cases, the strand may be visibly separate from the small signal line <NUM>.

The small cell apparatus <NUM> includes a housing <NUM> with a mounting structure <NUM> that couples the apparatus <NUM> to, in this example, the strand <NUM>. The housing <NUM> may be weather resistant to provide protection from the elements, especially rain, snow, or ice. The housing <NUM> may also provide interior mounting surfaces for the various components making up the small cell apparatus <NUM>. The apparatus <NUM> may also include an antenna <NUM>, although in some embodiments the antenna <NUM> may be internal to the housing <NUM>. Various electronics <NUM> may be mounted inside the housing <NUM> as illustrated in <FIG>.

The small cell apparatus <NUM> may include various mechanical, electrical, and electronic components as illustrated in <FIG>. A power supply <NUM> may supply power to the other components of the apparatus <NUM> and may include a battery or high value capacitor to maintain power at the apparatus <NUM> should external power be interrupted.

A first radio <NUM> supports communication with subscriber units for voice and data communications in accordance with known standards such as <NUM> LTE, <NUM>, WiFi, etc. The first radio may operate on first frequency in accordance with the appropriate standard and local configuration. A backhaul communications device <NUM> may transport subscriber unit communication to and from a hub, switch, or router associated with completing a communication path to a destination service or device.

A motion sensing device <NUM> is configured to use one or more techniques to detect movement of the apparatus <NUM>. The motion sensing device <NUM> is discussed in more detail below with respect to <FIG>.

A second radio <NUM> is used to transmit motion data from the motion sensing device <NUM> to a server or analysis center (not depicted). In some embodiments, the second radio <NUM> may be integral to the motion sensing device <NUM>. In some embodiments, the second radio <NUM> may contain its own battery <NUM> for powering the unit, such as a long-life lithium ion battery that may power the second radio (and optionally, the corresponding sensors in the motion sensing device <NUM>) for up to several years. In other cases, the second radio <NUM>, the entire motion sensing device <NUM>, or both, may be powered via the apparatus power supply <NUM>. The second radio <NUM> may also include a subscriber identify module (SIM) <NUM> for use in identification of the motion sensing device <NUM> as well as for security purposes including key storage, authentication, and data encryption.

The second radio may use a specialized protocol to optimize for efficiency, especially since the motion sensing device <NUM> may not require high data rates but in this application conservation of battery life may be important. Some protocols that may be useful in this application are lightweight machine-to-machine (LwM2M), narrowband Internet-of-Things (NB-loT), long range (LoRa), or differential binary phase shift keying (DBPSK) from SigFox, etc. In some embodiments, the motion data may be communicated via the backhaul communications device <NUM>.

A cooling device <NUM> may be used to cool the small cell apparatus <NUM>, or in some cases, may be part of the motion sensing device <NUM> for providing cooling to the device <NUM>. In some locations, particularly a strand mount in a desert climate, the apparatus <NUM> may be exposed to direct sun over a long period of time, requiring some form of cooling. The cooling device <NUM> may be passive, such as cooling fins, may be active, such as a fan, or may be a combination of both. In other embodiments, another form of cooling may be used, such as a circulating liquid.

Turning to <FIG>, a block diagram of an exemplary motion sensing device <NUM> is discussed and described. The motion sensing device <NUM> includes one or more accelerometers <NUM>, <NUM><NUM>. The accelerometers <NUM>, <NUM>, <NUM> may be mounted orthogonally to provide measurements in different axes. For example, in a strand-mounted apparatus, movement parallel to the strand <NUM> may be limited by the mounting structure <NUM> while movement perpendicular to the strand may occur due to any of the environmental conditions described above. For that reason, the one or more accelerometers <NUM>, <NUM> is mounted to detect motion normal to the strand. In some embodiments, the motion sensing device <NUM> may include the third axis sensor <NUM>, depending on the mounting arrangement and the influences for motion. Some prepackaged accelerometers include multi-axis sensors and may be suitable for this application. The accelerometers <NUM>, <NUM>, <NUM> may be mounted to the housing <NUM> or to an antenna <NUM> or an antenna support. A Global Navigation Satellite System (GNSS) <NUM>, such as GPS or Glonass, may also be part of the motion sensing device <NUM>. Signals received via the GNSS antenna <NUM> may be used to observe movement of the motion sensing device <NUM>. A vibration sensor <NUM> may be included in the motion sensing device <NUM>. While the vibration sensor <NUM> may simply be another form of accelerometer, the vibration sensor <NUM> may be sensitive at a higher frequency so that, for example, harmonic motion at a higher frequency that that caused by simple wind sway may be detectable.

An optical sensor <NUM> is used to detect motion in conjunction with one or more of the other sensors described. The optical sensor may operate in the visible light band or may operate in a non-visible spectrum such as infrared. Optical processing is used to detect motion by comparing the image features of known fixed objects, such as a nearby building, to current images to detect a shift indicating movement. In an embodiment, the optical sensor <NUM> may be directed to an object offline from any expected motion so that the shift in image may be more prominent. It is anticipated that in various embodiments, as few as one sensor up to all the sensors described or others may incorporated into the motion sensing apparatus <NUM>.

A processor <NUM>, such as a single chip computer or other controller may collect data from the various sensors <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> that are present in any given embodiment and transmit that data, via the second radio <NUM> for analysis. In operation, the motion sensing device <NUM> may be configured collect data at a given rate, such as every <NUM> milliseconds, and report the collected data periodically, such as once an hour. In another embodiment, the motion sensing device <NUM> may only report motion data when a certain motion threshold is reached. In some embodiments, such a threshold may include a minimum amount of movement, a minimum duration of movement, or both. In other embodiments, the motion sensing device <NUM> may be polled, for example, so that the external analysis service requests data only when errors associated with the cell apparatus <NUM> are observed. The unit may be independently powered by a battery <NUM>. In other embodiments, the motion sensing device <NUM> may use external power.

<FIG> is a flowchart of a method <NUM> of detecting motion in a small cell apparatus <NUM>. At block <NUM>, the small cell apparatus <NUM> may be coupled to a support using a mounting structure <NUM>. In some embodiments, the support may be a strand <NUM> of a small signal line. In other embodiments, the apparatus <NUM> may be mounted to a mast or other structure subject to sway or vibration. The small cell apparatus <NUM> may include an integral motion sensing device <NUM> as well as at least one radio <NUM> that communicates with subscriber equipment.

The motion sensing device <NUM> may collect data related to motion of the small cell apparatus <NUM>. The data may be collected, at block <NUM>, at a periodic rate or may be collected only when a predetermined motion threshold has been reached. In this exemplary embodiment, at block <NUM>, a test is performed to determine if criteria for sending the motion data to a server for analysis has been met. The criteria may be or include expiration of a time period for reporting, being polled by the server for data, or when the motion data indicates a condition that merits monitoring. If the criteria is not met, execution may follow the 'no' branch back to block <NUM>. If the criteria is satisfied, execution may follow the 'yes' branch to block <NUM>, where the data may be sent to the server for analysis. In an embodiment, after the current data is downloaded any internal memory buffers may optionally be cleared at block <NUM> and execution may continue at block <NUM>.

A technical effect of the disclosed system is a capability of the small cell apparatus <NUM> to determine whether it is moving and report such movement to a server or analysis process. The ability to self-detect motion may provide valuable insight into data rate changes and errors associated with the apparatus <NUM>. The need for this type of detailed information did not exist in previous generations of base station equipment because tower and building mounted transmitters/antenna, particularly those operating at much lower frequencies, were not subject to disruption due to movement.

Both system operators and subscribers benefit from the ability to identify movement of a small cell apparatus <NUM> and from the corresponding ability to correlate that motion with transmission rate reductions and errors. Subscribers may experience fewer dropped calls and higher data rates while operators are able to meet quality of service (QoS) obligations and satisfy their subscribers.

The figures depict preferred embodiments for purposes of illustration only.

Upon reading this disclosure, those of skill in the art will appreciate still additional alternative structural and functional designs for the systems and methods described herein through the disclosed principles herein. Thus, while particular embodiments and applications have been illustrated and described, it is to be understood that the disclosed embodiments are not limited to the precise construction and components disclosed herein. Various modifications, changes and variations, which will be apparent to those skilled in the art, may be made in the arrangement, operation and details of the systems and methods disclosed herein without departing from the scope defined in any appended claims.

Claim 1:
A small cell apparatus (<NUM>) configured to detect and report motion, the small cell apparatus (<NUM>) comprising:
a housing (<NUM>) including a mounting structure (<NUM>);
a first radio (<NUM>) coupled to the housing (<NUM>) that transmits and receives signals with communication system subscriber units;
a motion sensing device (<NUM>) coupled to the housing (<NUM>), wherein the motion sensing device includes at least one accelerometer (<NUM>, <NUM>, <NUM>) that are mounted to detect motion normal to a strand (<NUM>) on which the small cell apparatus (<NUM>) is mounted, and at least one optical sensor (<NUM>), optical
processing being used to detect motion by comparing known image features of fixed objects to current image features of the fixed objects in order to detect a shift indicating movement; and
a second radio (<NUM>) coupled to the housing (<NUM>) and communicatively coupled to the motion sensing device (<NUM>), the second radio (<NUM>) communicating data received from the motion sensing device (<NUM>) to a remotely located analysis unit.