1. Field of the Disclosure
The present invention relates generally to wireless communication, and more particularly to configuring antenna arrays of mobile wireless devices using motion sensors.
2. Description of the Related Art
Wireless communication is being used in a plethora of mobile devices, such as in laptops, cell phones, and other communication devices. Some mobile wireless devices obtain connectivity to a wireless network via a peer wireless device while others rely on an Access Point (AP) to provide connectivity to the wireless network. However, AP locations may be scattered or sparse thereby limiting the reception range for the mobile wireless device. Some mobile wireless devices monitor at regular intervals, parameters indicative of the reception range of a communications channel. In the event that a mobile wireless device's reception range is weak, the orientation of the mobile wireless device's antenna can be altered to a new orientation thereby improving the device's reception range. Various techniques can be used to determine the new configuration of the antenna's orientation. These techniques can consume significant processing time and power and as such, are typically performed on a periodic basis. However, in situations where a mobile wireless device is moving continuously and rapidly, these techniques may not be able to adapt to the sudden changes in the device's orientation in a timely manner to improve the device's reception range. Therefore, improvements in mobile wireless communications are needed.
Embodiments of the invention relate to a mobile wireless device that includes an antenna array for receiving and/or transmitting wireless signals, a motion sensor coupled to the antenna array, and a first circuitry coupled to the antenna array. The motion sensor is used to dynamically adjust in real-time the orientation of the antenna array due to a detected change in the movement of the antenna array. The first circuitry compares new values received from the motion sensor to a stored value corresponding to the most recent configuration of the antenna array, and determines an ideal antenna configuration in response to the antenna's movement.
In some embodiments, the antenna array is a sectorized antenna array. In response to the motion sensor detecting a change in orientation, the method may select and activate a sector antenna in the sector antenna array in response to the detected change in orientation. In other embodiments, the antenna array is an array of omnidirectional antennas. In response to detecting a change in orientation, a determination may be made as to whether the detected change meets or exceeds a specified threshold. If it is determined that the change in orientation meets or exceeds the threshold, then beamforming coefficients or other beam parameters, may be reconfigured to recalibrate the antenna array in response to the detected change in orientation.
A better understanding of the present invention can be obtained when the following Detailed Description of the Embodiments is read in conjunction with the following drawings, in which:
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
Embodiments of the mobile wireless device disclosed herein may operate to reconfigure its antenna array based on detected changes in the device's orientation by an onboard motion sensor.
In some embodiments, the antenna array is a sectorized antenna array. In response to a motion sensor detecting a change in orientation, the method may reconfigure the antenna array in response to the detected change in orientation. Reconfiguring the antenna array may include activating one or more sector antennas, and/or deactivating at least one sector antenna. The determination of an ideal sector can be based on detecting or receiving the strongest signal based on the change in orientation, and may select that sector antenna for activation, possibly deactivating any other active sector antennas with weaker reception.
In other embodiments, the antenna array is an array of omnidirectional antennas. In response to detecting a change in orientation, a determination may be made as to whether the detected change meets or exceeds a specified threshold. The specified threshold is indicative of the degree of change that warrants the need to alter the antenna orientation. The threshold may be a specified change in angle, such as azimuthal angle, or possibly a three dimensional angle or a set of angles such as Euler angles, among other means of expressing changes in orientation. If it is determined that the change in orientation meets or exceeds the threshold, then new beamforming coefficients, or other beam parameters, such as phase relationships, may be determined by recalibrating the antenna array in response to the detected change in orientation.
The beamforming coefficients may be determined as part of a recalibration procedure. In various embodiments, the recalibration of the antenna array may be performed using any explicit or implicit techniques in accordance with the IEEE 802.11 wireless transmission protocol, among others. In one embodiment, the method may include receiving channel state information (CSI), from an AP, and recalibrating the antenna based on the received CSI. The channel state information can contain specified information or attributes of a communication link that can be used to assess transmission/reception conditions, including, for example, effects of scattering, fading, and/or power decay with distance, which may facilitate adaptation of the antenna array configuration to current channel conditions.
In other embodiments when the change in orientation meets or exceeds the threshold, then new beamforming coefficients may be determined in response to the detected change in orientation without recalibrating the antenna array. The determination of the new beamforming coefficients may be made via any of a variety of techniques that do not include recalibration, including simple interpolation or extrapolation, statistical models, heuristics, neural networks, support vector machines, fuzzy logic, rule-based systems, historical data, lookup tables, and so forth, as desired. More generally, any technique that correlates absolute or relative changes in orientation with beam parameter values may be utilized as desired. Determining the new antenna configuration in this manner results in significant savings in time, power consumption, and computational bandwidth. There is also the additional benefit of a faster response time and a reduction in consumption of the wireless medium since the device does not have to request a new CSI and wait for its arrival.
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The mobile wireless device 100 may include a motion sensor that can determine the orientation of the device or its antenna array. The term “motion sensor” refers to a component that detects movement or changes in a device's movement, which may be accomplished by directly detecting a change in orientation or by determining a relative difference in the change of position. Examples of the motion sensor can include one or more accelerometers, one or more magnetic sensors, one or more optical sensors, one or more position sensors, one or more orientation sensors, and/or one or more gyroscopes. The motion sensor may be implemented using any technology desired, including, for example, microelectromechanical systems (MEMS) technology.
Note that motion sensors may include orientation sensors and be included in mobile devices, such as gaming devices, locationing devices such as GPS (Global Position System) devices, and some smartphones, etc., for uses such in gaming, text-orientation, etc. In some embodiments, these pre-existing motion sensors may be used to detect the orientation of the device or the device's antenna array, as described herein. In other words, in some embodiments, the mobile wireless device 100 may have one or more motion sensors for performing orientation functionality for the device for purposes that may be otherwise unrelated to the functionality disclosed herein, and these motion sensors can be used to implement embodiments described herein. The use of these existing motion sensors may provide savings with regard to the design, operation and manufacture of the device.
Attention now turns to a discussion on beamforming. The IEEE 802.11n 2009 standard offers beamforming techniques to create a virtual array of antennas that form high-gain beams focused at client mobile wireless devices. Focusing beams has the impact of increasing range and lowering overall environmental interference. Specifically, rather than radiate energy in all directions, transmit energy is focused directly at the intended receiver. Such a focused beam ensures that the majority of the energy transmitted will reach the proper receiver. In addition, focused beams may reduce the amount of energy sent in other directions and thereby cause less interference with other wireless links.
Maximizing the accuracy of these beams is important to achieving the highest effective throughput. Unless a signal can be sufficiently sustained from transmitter to receiver, errors and noise may erode throughput. For example, coding losses, lack of phase alignment, and marginal demodulation between multiple receivers results in higher bit error rates (BER) that may lead to more retransmissions, wasted signal energy, and greater interference.
Transmit Beamforming (TxBF) is a technology that enhances the reliability and performance of beamformed links by allowing the transmitter to generate signals that can be better received. Beamforming may use sounding techniques to align the transmitter with the receiver. The transmitter sends a signal and listens for a response from the receiver. By changing the characteristics of the transmission, such as by modifying beam parameters such as beam coefficients or phase relationships, the transmitter can hone in on the receiver's location to tune the beam to be as narrow as possible. This process is referred to as calibration (or recalibration), and thus may include determining transmission and/or reception conditions.
With open loop beamforming techniques, the transmitter is effectively forced to estimate where the receiver is and whether a change would improve or degrade signal reception. When signals and reflections arrive in phase, they add their energy to create the strongest possible signal. However, when they arrive out of phase, they begin to destructively interfere with each other, reducing the signal energy reaching the receiver. Ideally, transmitted signals and their reflections arrive phase-aligned at the receive antenna. One example of open loop beamforming is often referred to as implicit beamforming. Implicit beamforming tasks the transmitter to determine beamforming coefficients (i.e., phase, amplitude and/or timing adjustments) assuming a reciprocal communication channel and typically based upon one or more signals sent by the receiver to the transmitter.
Closed loop TxBF techniques improve accuracy by enabling the receiver to provide direct feedback to the transmitter to maximize the phase alignment of signals and their reflections. Closed loop TxBF opens a channel to the transmitter that allows the receiver to provide specific data on how well it is receiving signals. In this way, the transmitter can more quickly and accurately assess the optimal beam to use. The final result of closed loop TxBF is a relatively accurate steering matrix that may be applied to signals before transmission. One example of closed loop beamforming is often referred to as explicit beamforming. Explicit beamforming tasks the receiver to determine beamforming coefficients based upon one or more signals sent by the transmitter to the receiver. These coefficients are then sent to the transmitter.
Generally, receive and transmit antennas in an antenna array may operate simultaneously through the respective parallel receive and transmit chains to perform beamforming, where antenna signals from multiple omnidirectional antennas are combined to maximize performance via determining or updating beamforming coefficients. The beamforming coefficients may configure the antennas to constructively and destructively interfere, resulting in an effective directional antenna pattern.
As
Other beamforming techniques can be used herein, such as those described in U.S. Pat. No. 7,366,089, entitled “Apparatus and Method of Multiple Antenna Receiver Combining of High Data Rate Wideband Packetized Wireless Communication Signals”, filed on Oct. 8, 2003, as well as U.S. Pat. No. 7,385,914, entitled, “Apparatus and Method of Multiple Antenna Transmitter Beamforming of High Data Rate Wideband Packetized Wireless Communication Signals”, also filed on Oct. 8, 2003, both of which are hereby incorporated herein by reference.
The mobile wireless devices 100C, 100D may also include antenna control circuitry 140A, 140B, which may be coupled to at least one antenna array, such as the sector antenna array 150 shown in
Each of the circuitries 120, 130, and/or 140 may be implemented using any one or more technologies, such as analog logic, digital logic, a processor and memory (such as a CPU, DSP, microcontroller, etc.), an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), mechanical and/or electrical components, actuators, servos, or any combination of the above.
Thus, the mobile wireless device 100 may include an antenna array 150, 160 for receiving and/or transmitting wireless signals, antenna control circuitry 140A, 140B for controlling the antenna array 150, 160 and a motion detection circuitry 130 for detecting changes in orientation of the mobile wireless device 100. The mobile wireless device 100 may also have circuitry for performing various other functions of the device, for example, device circuitry 120, as would be known to one of ordinary skill in the art.
The antenna control circuitry 140A, 140B may utilize detected changes in the orientation of the wireless device to control the configuration of the antenna array. In other words, information from the motion sensor(s) may be used to detect a change in orientation of the mobile wireless device or its antenna array. This information may be used to detect the need for, trigger, or even to determine, a reconfiguration of the mobile wireless device's antenna.
For example, in embodiments where the antenna array is a sector antenna array 150, as shown in
In embodiments where the antenna array includes multiple omnidirectional antennas, such as shown in
For gaming applications running on a mobile wireless device, there are often sudden movements of the mobile wireless device often resulting in rapid changes in the orientation of a mobile wireless device's antenna. The motion detection circuitry 130 would detect these sudden movements and notify the antenna control circuitry 140A, 140B of the change in orientation. This notification would allow the antenna control circuitry 140A, 140B to update the antenna array configuration when the orientation is changing rapidly, while allowing longer use of configurations when the orientation is changing more slowly.
In step 402, a change in orientation of the antenna array 150, 160 may be detected via the motion sensor in the motion detection circuitry 130. For example, in one exemplary embodiment, the motion detection circuitry 130 may monitor or poll the motion sensor. The motion detection circuitry 130 may compare new values from the motion sensor to a stored value corresponding to the most recent reconfiguration, and determine whether the difference exceeds some specified threshold. Note that changes in orientation of the antenna array may be due to any of various types of motion of the wireless device. Exemplary types of motion include rotations and/or translations of the mobile wireless device. As another example, moving in a non-radial direction with respect to a signal source may change the orientation of the device's antenna array with respect to the signal source without rotation.
In step 404, the antenna array 150, 160 may be reconfigured by the antenna control circuitry 140A, 140B in response to the detected change in orientation. In one embodiment, the first circuitry may determine an ideal configuration and reconfigure the antenna array 150, 160 within an acceptable tolerance of the ideal configuration. For example, within 10%, 5%, 2%, or 1% of the ideal configuration, depending on acceptable tolerances of a given application.
In step 502, a change in orientation of the sector antenna array 150 may be determined via the motion sensor in the motion detection circuitry 130. The motion detection circuitry 130 may monitor or poll the motion sensor. The motion detection circuitry 130 may compare new values from the motion sensor to a stored value corresponding to the most recent reconfiguration, and may determine the difference, such as a difference in orientation angle(s). In one embodiment, the motion detection circuitry may also determine whether the difference exceeds a specified threshold. Thus, in some embodiments, the motion detection circuitry 130 may detect a change in orientation, and may also determine the amount of the change.
In step 504, the method 500 may select and activate a sector antenna of the sector antenna array 150 in response to the detected change in orientation. Thus, reconfiguring the antenna array may include activating one or more sector antennas, and/or deactivating at least one sector antenna. For example, the method may determine which of the sector antennas detects or receives the strongest signal, and may select that sector antenna for activation. In some cases, the method may deactivate other active sector antennas with weaker reception. In some embodiments, the antenna control circuitry 140A may determine an improved configuration for the sector antenna array 150 without determining and performing an analysis of current conditions. In some embodiments, the reconfiguration may only be performed if the difference in orientation, or amount of change in orientation, exceeds a specified threshold.
In step 602, a change in orientation of the antenna array 160 may be determined by the motion detection circuitry 130. The motion detection circuitry 130 notifies the antenna control circuitry 140B. In step 603, a determination may be made as to whether the detected change meets or exceeds a specified threshold. For example, the threshold may be a specified change in angle, such as azimuthal angle, or possibly a three dimensional angle or a set of angles such as Euler angles, among other means of expressing changes in orientation. If the detected change does not meet or exceed the threshold (step 603—no), then the method may return to 602, and continue to monitor for a detected change in orientation. Otherwise, if it is determined that the change in orientation does meet or exceed the threshold (step 603—yes), then in step 604, new beamforming coefficients (or other beam parameters, such as phase relationships) may be determined by recalibrating the antenna array in response to the detected change in orientation.
The new beamforming coefficients may be determined as part of a recalibration procedure. In various embodiments, the recalibration of the antenna array may be performed using any explicit or implicit techniques well known in the art. For example, in one embodiment, the method may include receiving channel state information (CSI), for example, from an AP, and recalibrating the antenna based on the received CSI. Note that as used herein, the term “channel state information” refers to specified information or attributes of a communication link that can be used to assess transmission/reception conditions, including, for example, effects of scattering, fading, and/or power decay with distance, which may facilitate adaptation of the antenna array configuration to current channel conditions.
Thus, in embodiments where the antenna array includes two or more omnidirectional antennas, reconfiguring the antenna array may include modifying beamforming coefficients of, and/or adjusting phase relationships among, two or more antennas in the antenna array, based on determined conditions via a recalibration process.
In step 702, a change in orientation of the omnidirectional antenna array 160 may be determined via the motion sensor in the motion detection circuitry 130. In step 703, a determination may be made as to whether the detected change meets or exceeds a specified threshold. If the detected change does not meet or exceed the threshold (step 703—no), the method 700 may return to step 702, and continue to monitor for a detected change in orientation. Otherwise, if it is determined that the change in orientation meets or exceeds the threshold (step 703—yes), new beamforming coefficients, may be determined in response to, and based on, the detected change in orientation, without recalibrating the antenna array (step 704). For example, the determination of the new beamforming coefficients may be made via any of a variety of techniques, such as, including simple interpolation or extrapolation, statistical models, heuristics, neural networks, support vector machines, fuzzy logic, rule-based systems, historical data, lookup tables, and so forth. More generally, any technique that correlates absolute or relative changes in orientation with beam parameter values may be utilized as desired. Determining the new configuration in this way, where the antenna array is reconfigured without recalibrating the antenna, may result in significant savings in time, power consumption, and computational bandwidth.
In some embodiments, combinations of the above-described techniques may be utilized. For example, for quick optimization or improvement, small changes in orientation, up to some cumulative maximum, special geometries, where the change in orientation is 180 degrees, and so forth, the reconfiguration without recalibration approach may be used. Otherwise, the reconfiguration may include recalibrating the antenna. In other embodiments, any of various conditions may be specified for determining which approach to use, possibly dynamically.
Although the embodiments above have been described in considerable detail, numerous variations and modifications will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such variations and modifications. Although the embodiments described herein have been discussed with respect to an access point, the embodiments can be applied to systems or networks where there are no access points. For example, in an ad hoc network, the functionality of an access point can be performed by one or more peer mobile wireless devices.