Patent Application
20140315572
The present invention relates to location estimation with a reduced number of frame exchanges between electronic devices in a wireless network system, and more particularly, to a method for performing timing measurement for location estimation of an electronic device, and to an associated apparatus.
According to the related art, a conventional electronic device in a wireless network system can be designed to determine the location of the conventional electronic device in a situation where the locations of three points in the wireless network system and the time of flight (or the time of electromagnetic wave propagation) between the conventional electronic device and each of the three points are known. However, some problems may occur. For example, multiple requests are required for triggering the timing measurement corresponding to the aforementioned three points, respectively. In another example, before performing the timing measurement respectively corresponding to the aforementioned three points, it is typically required to send additional probe frames from the conventional electronic device to discover peer devices in the wireless network system, causing the power consumption of the conventional electronic device to be increased. More particularly, as the number of frame exchanges for the timing measurement is typically proportional to the number of peer devices under consideration and the frequency of updates, the total channel capacity of the wireless network system may be insufficient in some situations (e.g. the frequency of updates increases, and/or the number of users who need positioning in the wireless network system is many). Thus, a novel method is required for improving the location estimation of an electronic device in a wireless network system.
It is an objective of the claimed invention to provide a method for performing timing measurement for location estimation of an electronic device, and to an associated apparatus, in order to solve the above-mentioned problems.
It is another objective of the claimed invention to provide a method for performing timing measurement for location estimation of an electronic device, and to an associated apparatus, in order to reduce the number of frame exchanges in a wireless network system.
According to at least one preferred embodiment, a method for performing timing measurement for location estimation of an electronic device is provided, where the method comprises the steps of: sending a pre-association broadcast request frame to trigger multiple responders in a wireless network system to initiate timing measurement; and performing timing measurement according to a plurality of timestamps, for determining a location of the electronic device, wherein a portion of the plurality of timestamps is obtained from the responders. For example, at least one timestamp is determined based on a pre-association uni-cast response frame received from one of the responders, wherein no actual association is established between the electronic device and any of the responders. More particularly, for a specific responder of the responders (e.g. the aforementioned one of the responders), a first timestamp and a second timestamp within the plurality of timestamps respectively correspond to a time of departure (ToD) and a time of arrival (ToA) of a pre-association uni-cast response frame received from the specific responder, and a third timestamp and a fourth timestamp within the plurality of timestamps respectively correspond to a ToD and a ToA of an acknowledgement frame corresponding to the pre-association uni-cast response frame received from the specific responder, the acknowledgement frame sent from the electronic device to the specific responder. For example, the pre-association broadcast request frame can be a probe request frame, and the pre-association uni-cast response frame received from the specific responder can be a probe response frame. In another example, the pre-association broadcast request frame can be a Generic Advertisement Service (GAS) request frame, and the pre-association uni-cast response frame received from the specific responder can be a GAS response frame.
According to at least one preferred embodiment, an apparatus for performing timing measurement for location estimation of an electronic device is provided, where the apparatus comprises at least one portion of the electronic device. The apparatus comprises a processing circuit arrange to control operations of the electronic device, and further comprises a transceiver arranged to transmit or receive information for the electronic device, where the processing circuit is coupled to the transceiver. In addition, the processing circuit sends, by utilizing the transceiver, a pre-association broadcast request frame to trigger multiple responders in a wireless network system to initiate timing measurement, and performs timing measurement according to a plurality of timestamps, for determining a location of the electronic device, wherein a portion of the plurality of timestamps is obtained from the responders. For example, at least one timestamp is determined based on a pre-association uni-cast response frame received from one of the responders, wherein no actual association is established between the electronic device and any of the responders. More particularly, for a specific responder of the responders (e.g. the aforementioned one of the responders), a first timestamp and a second timestamp within the plurality of timestamps respectively correspond to a ToD and a ToA of a pre-association uni-cast response frame received from the specific responder, and a third timestamp and a fourth timestamp within the plurality of timestamps respectively correspond to a ToD and a ToA of an acknowledgement frame corresponding to the pre-association uni-cast response frame received from the specific responder, the acknowledgement frame sent from the electronic device to the specific responder. For example, the pre-association broadcast request frame can be a probe request frame, and the pre-association uni-cast response frame received from the specific responder can be a probe response frame. In another example, the pre-association broadcast request frame can be a GAS request frame, and the pre-association uni-cast response frame received from the specific responder can be a GAS response frame.
It is an advantage of the present invention that the present invention method and apparatus can use merely one request (more particularly, a request sent from the electric device to multiple peer devices) to immediately start performing timing measurement for location estimation. In addition, in comparison with the related art, the number of frame exchanges in a wireless network system is greatly reduced, where additional probe frames are not required. As a result, the power consumption can be decreased, and the problem of insufficiency of the total channel capacity of the wireless network system can be prevented.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
Certain terms are used throughout the following description and claims, which refer to particular components. As one skilled in the art will appreciate, electronic equipment manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but not in function. In the following description and in the claims, the terms “include” and “comprise” are used in an open-ended fashion, and thus should be interpreted to mean “include, but not limited to . . . ”. Also, the term “couple” is intended to mean either an indirect or direct electrical connection. Accordingly, if one device is coupled to another device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
Please refer to
As shown in
According to this embodiment, the processing circuit 110 may send, by utilizing the transceiver 120, a pre-association broadcast request frame to trigger some peer devices in a wireless network system to initiate timing measurement. The peer devices may respond to the pre-association broadcast request frame by sending pre-association uni-cast response frames to the electronic device, respectively, so the aforementioned timing measurement can be performed immediately. Thus, the electronic device can be regarded as the initiator, and the peer devices can be regarded as the responders. More particularly, the initiator may uses the pre-association broadcast (or multicast) request frame, such as a probe request or a Generic Advertisement Service (GAS) request, as a timing measurement request to solicit multiple responders to directly perform timing measurement operations such as some interactions for measuring the time of flight (or the time of electromagnetic wave propagation) between the electronic device and each of the responders whose locations are known. For example, each of the responders may send a pre-association uni-cast response frame, such as a probe response frame or a GAS response frame, as a timing measurement frame. Regarding determining the location of the electronic device in a situation where the locations of three points in the wireless network system and the time of flight (or the time of electromagnetic wave propagation) between the electronic device and each of the three points are known, please refer to Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards (e.g. “IEEE 802.11-2012” standards) for more information when needed.
As a result of using the pre-association broadcast request frame to simultaneously trigger the responders to initiate the timing measurement, the total number of exchange frames of multiple peers can be reduced significantly in comparison with the related art, where it is unnecessary to perform peer-to-peer IEEE 802.11v timing measurement frame handshaking of the related art before the feedback of the timing measurement report. In addition, the time and power consumption of the additional discovery phase of the related art and the information query phase of the related art can be saved since all information required can be obtained during (or before) the timing measurement process triggered by the pre-association broadcast request frame. For example, the locations of the three points can be carried by the aforementioned pre-association uni-cast response frames, and therefore can be sent to the electronic device right after the pre-association broadcast request frame is sent. In another example, the locations of the three points can be retrieved from the Internet or somewhere else in the wireless network system in advance, rather than being sent from the responders at this moment during the timing measurement.
In Step 310, the processing circuit 110 sends, by utilizing the transceiver 120, a pre-association broadcast request frame such as that mentioned above to trigger multiple responders in a wireless network system such as the wireless network system 200 to initiate the timing measurement. For example, the pre-association broadcast request frame can be a probe request frame. In another example, the pre-association broadcast request frame can be a GAS request frame.
In Step 320, the processing circuit 110 performs timing measurement according to a plurality of timestamps, for determining a location of the electronic device, where a portion of the plurality of timestamps can be obtained from the responders, and another portion of the plurality of timestamps can be determined within the electronic device. For example, within the plurality of timestamps, at least one timestamp can be determined based on a pre-association uni-cast response frame received from one of the responders, such as the pre-association uni-cast response frame mentioned in the embodiment shown in
According to this embodiment, for a specific responder of the responders (e.g. the aforementioned one of the responders), a first timestamp t1 and a second timestamp t2 within the plurality of timestamps respectively correspond to a time of departure (ToD) and a time of arrival (ToA) of a pre-association uni-cast response frame received from the specific responder, and a third timestamp t3 and a fourth timestamp t4 within the plurality of timestamps respectively correspond to a ToD and a ToA of an acknowledgement (or ACK) frame corresponding to this pre-association uni-cast response frame, the acknowledgement frame sent from the electronic device to the specific responder. For example, in a situation where the pre-association broadcast request frame is a probe request frame, this pre-association uni-cast response frame can be a probe response frame. In another example, in a situation where the pre-association broadcast request frame is a GAS request frame, this pre-association uni-cast response frame can be a GAS response frame.
More particularly, the aforementioned specific responder may represent each responder of at least one portion (e.g. a portion or all) of the responders. For example, the specific responder may represent each responder of a portion of the responders. This is for illustrative purposes only, and is not meant to be a limitation of the present invention. In another example, the specific responder may represent each of the responders.
According to some embodiments of the present invention, such as some variations of the embodiment shown in
As shown in
ToF=((t4−t1)−(t3−t2))/2;
where the distance between the initiator and the specific responder can be determined or estimated to be (c*ToF), with the notation “c” representing the speed of light in vacuum. That is, the initiator, i.e. the electronic device of this embodiment (more particularly, the processing circuit 110 therein), can determine or estimate the distance between the initiator and the specific responder based on the following equation:
D=(c*ToF)=c*((t4−t1)−(t3−t2))/2;
where the notation “D” represents the distance between the initiator and the specific responder. As a result, the distance D between the electronic device and the specific responder can be utilized for determining the location of the electronic device.
Please note that similar operations may be applied to the interactions between the initiator and another responder such as that mentioned above (more particularly, any of the other responders within the responders mentioned in Step 310, i.e. any responder within the responders mentioned in Step 310 except for the specific responder mentioned above). In another example, the other responder may send another one of the uni-cast response frames shown in
ToF′=((t4′−t1′)−(t3′−t2′))/2;
where the distance between the initiator and the other responder can be determined or estimated to be (c*ToF′), with the notation “c” representing the speed of light in vacuum. That is, the initiator, i.e. the electronic device of this embodiment (more particularly, the processing circuit 110 therein), can determine or estimate the distance between the initiator and the other responder based on the following equation:
D′=(c*ToF′)=c*((t4′−t1′)−(t3′−t2′))/2;
where the notation “D′” represents the distance between the initiator and the other responder. As a result, the distance D′ between the electronic device and the other responder can be utilized for determining the location of the electronic device.
In general, the equations disclosed above can be collectively expressed as follows:
ToF(n)=((t4(n)−t1(n))−(t3(n)−t2(n)))/2; and
D(n)=(c*ToF(n))=c*((t4(n)−t1(n))−(t3(n)−t2(n)))/2;
where the index n corresponds to the responder under consideration within the responders, such as the responder R(n) (e.g. the specific responder, or the other responder mentioned above). Thus, the initiator and the responder R(n) are arranged to capture four timestamps including ToDs and ToAs for a transmitted response frame and the corresponding ACK frame, respectively, where the responder R(n) uses a uni-cast report frame to provide its locally captured timestamps to the initiator. As a result, the initiator can determine or estimate a set of time of flight {ToF(n)} relative to the aforementioned multiple responders using the plurality of timestamps. In addition, the initiator can further determine or estimate a set of distances {D(n)} between the initiator and the responders {R(n)}, respectively, in order to determine the location of the initiator, i.e. the location mentioned in Step 320. Please note that the initiator may utilize a terminate frame (which is a broadcast or multicast frame) to cancel the measurement process if known points are enough to calculate the aforementioned location of the electronic device.
Based on the method 300 shown in
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
This application claims the benefit of U.S. Provisional Application No. 61/813,198, which was filed on Apr. 18, 2013, and is included herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61813198 | Apr 2013 | US |
