Patent Application
20150045022
Embodiments pertain to wireless communications. Some embodiments relate to indoor navigation. Some embodiments relate to systems and methods to select access points for performing time-of-flight location techniques.
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. Some embodiments are illustrated by way of example, and not limitation, in the figures of the accompanying drawings in which:
The following description and the drawings sufficiently illustrate specific embodiments to enable those skilled in the art to practice them. Other embodiments may incorporate structural, logical, electrical, process, and other changes. Portions and features of some embodiments may be included in, or substituted for, those of other embodiments. Embodiments set forth in the claims encompass all available equivalents of those claims.
Outdoor navigation is widely deployed through the development of various global navigation satellite systems (GNSS) such as GPS, GLONASS and GALILEO. However, the field of indoor navigation is still developing. This field differs from the outdoor navigation because indoor environment typically prevent the reception of signals from GNSS satellites or degrade their level beyond usable levels. As a result, there is a need to provide an indoor navigation solution with satisfactory precision.
The time-of-flight (ToF) method of location may be defined as the overall time a signal propagates from a device to an access point (AP) and back to the device. This value can be converted into a distance value by dividing the time by two and multiplying that result by the speed of light. ToF calculations typically rely on the device knowing the basic parameters and location of one or more access points.
The radio strength signal indication (RSSI) method of location may be defined as determining a distance between a device and an AP based on signal strength received by the device from the AP or vice-versa. This value can be converted into a distance value by calculating a signal loss based on a known, expected, or exchanged signal strength. RSSI calculations typically rely on the device knowing the basic transmitter parameters and location of one or more access points.
Venues such as shopping malls, stadium, etc. may have hundreds, or more, APs. The device typically locates the proper APs to perform the measurements utilizing selection criteria such as the AP location or signal strength. Performing the ToF or RSSI algorithms for selecting APs can reach high computational complexity on the order of N-squared, which will typically consume device power in an inefficient manner, and creates additional latency for the overall location computation time.
Example embodiments discussed herein include an approach for representing an AP database that will enable a device to significantly reduce the computation complexity of the AP selection algorithm. In an example, the computation complexity is reduced, in the worst case, to O(N).
The network equipment 102 is illustrated in
Communication devices 104A, 104B, 104C may communicate with the network equipment 102 when in range or otherwise in proximity for wireless communications. As illustrated, the connection 106A may be established between the mobile device 104A (e.g., a smartphone) and the network equipment 102; the connection 106B may be established between the mobile device 104B (e.g., a mobile phone) and the network equipment 102; and the connection 106C may be established between the mobile device 104C (e.g., a personal computer) and the network equipment 102.
The wireless communications 106A, 106B, 106C between devices 104A, 104B, 104C may utilize a Wi-Fi or IEEE 802.11 standard protocol, or a protocol such as the current 3rd Generation Partnership Project (3GPP) long term evolution (LTE) time division duplex (TDD)-Advanced systems. In an embodiment, the communications network 116 and network equipment 102 comprises an evolved universal terrestrial radio access network (EUTRAN) using the 3rd Generation Partnership Project (3GPP) long term evolution (LTE) standard and operating in time division duplexing (TDD) mode. The devices 104A, 104B, 104C may include one or more antennas, receivers, transmitters, or transceivers that are configured to utilize a Wi-Fi or IEEE 802.11 standard protocol, or a protocol such as 3GPP, LTE, or TDD-Advanced or any combination of these or other communications standards.
Antennas in or on devices 104A, 104B, 104C may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, antennas may be effectively separated to utilize spatial diversity and the different channel characteristics that may result between each of the antennas and the antennas of a transmitting station. In some MIMO embodiments, antennas may be separated by up to 1/10 of a wavelength or more.
In some embodiments, the mobile device 104A may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen. The mobile device 104B may be similar to mobile device 104A, but does not need to be identical. The mobile device 104C may include some or all of the features, components, or functionality described with respect to mobile device 104A.
A base station, such as an enhanced or evolved node B (eNodeB), may provide wireless communication services to communication devices, such as device 104A. While the exemplary communication system 100 of
Although communication system 100 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of system 100 may refer to one or more processes operating on one or more processing elements.
Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. In some embodiments, system 100 may include one or more processors and may be configured with instructions stored on a computer-readable storage device.
In an example, a second access point 208 or a third access point 210 may be within range of the device 202. The device 202 may communicate with the first access point 204, the second access point 208 or the third access point 210. The device 202 may request location information regarding one or more of the first access point 204, the second access point 208, the third access point 210, or any other access point 218, from the access point server 214. In response to the location information request, the secure access point locations server 214 may provide the device 202, via connection 216, with the location information corresponding to the requested access point. In an example, the access point server 214 may also provide the device 202 with one or more keys that the device 202 may utilize to securely communicate with the requested access point.
The first access point 204, the second access point 208, and the third access point 210 may all provide timing and/or location information to the device 202 over a secure communication link that may be established using a key, or other security information obtained by the device 202, from the access point server 214. The timing information may include time-of-arrival or time-of-departure data with respect to the TOF protocol exchange that are local to the each access point. The location information may include an updated location of a respective access point.
In an example, device 202 may include an access point (AP) database that includes a representation of the first access point 204, the second access point 208, and the third access point 210. The AP database may be utilized by the device 202 to select the access points that the device 202 will communicate with in order to perform location measurements. In an example, the device 202 may be configured to select the access points with the use of a selection algorithm that is performed in a constant time or with a constant number of operations for any number of elements in the access database, e.g., on the order of one O(1).
In an example, the device 202 may obtain various information regarding individual access points, such as: a BSSID, a location, and/or a set of capabilities (e.g., bandwidth, modulation coding scheme (MCS), ToF support, etc.) in order to select an AP for performing a ToF calculation. Determining an appropriate AP may start with searching for the access points that are estimated to be the closest to the device location. Typically, the closest access points (e.g., an AP with the strongest signal(s) received by a device) have the most influence on the accuracy level of the ultimate location calculation.
At least two issues are present in determining an appropriate AP for performing the ToF calculation. First, it may be useful to sort an AP database stored on the device 202 from the nearest AP to the device (associated or strongest RSSI) to the farthest AP. This sort may generally be estimated as being performed in quadratic time, e.g., O(N*N), or linearithmic time e.g., O(N*log(N)). Second, not all APs may not necessarily be stored or represented in the same coordinate system, so part of the computation complexity may include converting an entire database, or at least portions of the database, to a uniform coordinate system.
These issues may be resolved in a variety of manners. For example, including the location of all access points in a list, such as a linked data structure, where the list includes access points that utilize the same coordinate system, may decrease the time or resources necessary to select an AP from the list. Additionally, each AP may include a link to up to a specified number (N) of other neighboring APs that are the closest to the AP (e.g., within a range where the APs may efficiently or reliably establish a connection).
Various protocols may publish the location of an AP in local coordinates, however, multiple access points in a single venue may be presented in a different coordinates system in some non-ideal circumstances. In an example, all the access points may be stored in a format compatible with a World Geodetic System (WGS), such as the WGS84 coordinate system, with additional information utilized to simplify the location computation.
In an example, a fourth access point 316 may form a terminal node such that it is only linked to a single access point, such as, the fourth link 314 between the second access point 306 and the fourth access point 316. The fourth access point 316 and the second access point 306 are direct neighbors, but the fourth access point 316 is not a direct neighbor with the access point 302.
In an example, a fifth access point 318 may form a terminal node that includes links to two or more access points. The fifth access point 318 is a direct neighbor to both the third access point 310 and the sixth access point 320. The example access point hierarchy 300 includes up to three neighbors for each AP, however, additional entries or links are contemplated. Although only seven access points are depicted in access point hierarchy 300 additional access points are contemplated.
In an example AP database, each time a device needs to select the best AP to perform location measurements, the device may sort all the DB according to their associated/strongest AP. However, this sorting operation may cause additional power consumption and creates additional latency for the overall location computation time. By providing the AP database to a device in a list format, where direct neighbors are linked in the list, a network equipment (e.g., access point) may decrease the processing burden on the device during the selection of which Aps the device should use to perform location measurements.
In an example, a device may utilize a “who are my neighbors” approach to eliminate the sorting process. The device may therefore also reduce the power and time needed to perform the selection process significantly, e.g., a linear time savings, up to O(N). In an example, the selection process may be further reduced if the AP list is stored or already sorted by basic service set identification (BSSID). In this scenario the selection process then may be performed in logarithmic time, e.g., within O log(N) time.
The plurality of properties may also include: a serial number (e.g., an integer value), an array of neighbors serial numbers, an items field, a floor name string, and a floor number value. The properties described herein may be modified to accommodate one or more protocol or navigation standards. Other properties may also be included.
In an example, a data structure may include all the access points with the following location information that may be utilized to establish a uniform coordinate system: latitude in WGS84, longitude in WGS84, lateral error, altitude above ellipsoid in WGS84, altitude above ellipsoid in WGS84 error, and height above a floor.
When the device is connected to an access point, then, at 507, the device may receive a copy of the AP database from the access point. The copy of the AP database may include all of the AP information known to or stored at the access point, or it may be a subset of the AP information. For example, an AP may only provide the device with a list of direct neighbors of the access point, or a list of direct neighbors and also neighbors of its direct neighbors.
At 508, the device will look up the identifier (e.g., BSSID) of the access point in its local copy of the access point database. In an example, the look up may be performed in logarithmic time e.g., within O log(N), where N is the number of entries in the database. At 510 the device may evaluate the neighbors of this access point, e.g., the direct neighbors that are closes to the access point. Neighbors of the access point may be indicated in the access point database by a pointer, vector, or other logical link in the list provided to the device by the access point. In an example, the evaluation may be performed in a constant, e.g., O(1), time.
At 512, the device may check to determine if additional information is needed from additional access points (e.g., neighbors of the direct neighbors of the access point) to successfully or accurately perform a ToF measurement. If more access points are needed, then, at 514, the device may connect to the next access point (e.g., a direct neighbor of the access point) in the AP hierarchy stored in the local access point database. If no additional access points are needed, then at 516, the device may perform any distance measurements according to any appropriate location protocol, such as ToF or RSSI techniques.
Though arranged serially in the example of
In some embodiments, a receiver implementing the access point database may be part of a portable wireless communication device, such as a personal digital assistant (PDA), a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly.
In some embodiments, a mobile device may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.
Although systems discussed herein may have several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements of system may refer to one or more processes operating on one or more processing elements.
Examples, as described herein, may include, or may operate on, logic or a number of components, modules, or mechanisms. Modules are tangible entities capable of performing specified operations and may be configured or arranged in a certain manner. In an example, circuits may be arranged (e.g., internally or with respect to external entities such as other circuits) in a specified manner as a module. In an example, the whole or part of one or more computer systems (e.g., a standalone, client or server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, an application portion, or an application) as a module that operates to perform specified operations. In an example, the software may reside (1) on a non-transitory machine-readable medium or (2) in a transmission signal. In an example, the software, when executed by the underlying hardware of the module, causes the hardware to perform the specified operations.
Accordingly, the term “module” is understood to encompass a tangible entity, be that an entity that is physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitorily) configured (e.g., programmed) to operate in a specified manner or to perform part or all of any operation described herein. Considering examples in which modules are temporarily configured, each of the modules need not be instantiated at any one moment in time. For example, where the modules comprise a general-purpose hardware processor configured using software, the general-purpose hardware processor may be configured as respective different modules at different times. Software may accordingly configure a hardware processor, for example, to constitute a particular module at one instance of time and to constitute a different module at a different instance of time.
Machine (e.g., computer system) 700 may include a hardware processor 702 (e.g., a processing unit, a graphics processing unit (GPU), a hardware processor core, or any combination thereof), a main memory 704, and a static memory 706, some or all of which may communicate with each other via a link 708 (e.g., a bus, link, interconnect, or the like). The machine 700 may further include a display device 710, an input device 712 (e.g., a keyboard), and a user interface (UI) navigation device 714 (e.g., a mouse). In an example, the display device 710, input device 712, and UI navigation device 714 may be a touch screen display. The machine 700 may additionally include a mass storage (e.g., drive unit) 716, a signal generation device 718 (e.g., a speaker), a network interface device 720, and one or more sensors 721, such as a global positioning system (GPS) sensor, camera, video recorder, compass, accelerometer, or other sensor. The machine 700 may include an output controller 728, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR)) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).
The mass storage 716 may include a machine-readable medium 722 on which is stored one or more sets of data structures or instructions 724 (e.g., software) embodying or utilized by any one or more of the techniques or functions described herein. The instructions 724 may also reside, completely or at least partially, within the main memory 704, within static memory 706, or within the hardware processor 702 during execution thereof by the machine 700. In an example, one or any combination of the hardware processor 702, the main memory 704, the static memory 706, or the mass storage 716 may constitute machine-readable media.
While the machine-readable medium 722 is illustrated as a single medium, the term “machine readable medium” may include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that configured to store the one or more instructions 724.
The term “machine-readable medium” may include any tangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine 700 and that cause the machine 700 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. Non-limiting machine-readable medium examples may include solid-state memories, and optical and magnetic media. Specific examples of machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.
The instructions 724 may further be transmitted or received over a communications network 726 using a transmission medium via the network interface device 720 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 700, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.
Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage device, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage device may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage device may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media.
In some embodiments, the UE 800 may include one or more of a keyboard, a display, a non-volatile memory port, multiple antennas, a graphics processor, an application processor, speakers, and other mobile device elements. The display may be an LCD screen including a touch screen.
The one or more antennas 801 utilized by the UE 800 may comprise one or more directional or omnidirectional antennas, including, for example, dipole antennas, monopole antennas, patch antennas, loop antennas, microstrip antennas or other types of antennas suitable for transmission of RF signals. In some embodiments, instead of two or more antennas, a single antenna with multiple apertures may be used. In these embodiments, each aperture may be considered a separate antenna. In some multiple-input multiple-output (MIMO) embodiments, the antennas may be effectively separated to take advantage of spatial diversity and the different channel characteristics that may result between each of antennas and the antennas of a transmitting station. In some MIMO embodiments, the antennas may be separated by up to 1/10 of a wavelength or more.
Although the UE 800 is illustrated as having several separate functional elements, one or more of the functional elements may be combined and may be implemented by combinations of software-configured elements, such as processing elements including digital signal processors (DSPs), and/or other hardware elements. For example, some elements may comprise one or more microprocessors, DSPs, application specific integrated circuits (ASICs), radio-frequency integrated circuits (RFICs) and combinations of various hardware and logic circuitry for performing at least the functions described herein. In some embodiments, the functional elements may refer to one or more processes operating on one or more processing elements.
Embodiments may be implemented in one or a combination of hardware, firmware and software. Embodiments may also be implemented as instructions stored on a computer-readable storage medium, which may be read and executed by at least one processor to perform the operations described herein. A computer-readable storage medium may include any non-transitory mechanism for storing information in a form readable by a machine (e.g., a computer). For example, a computer-readable storage medium may include read-only memory (ROM), random-access memory (RAM), magnetic disk storage media, optical storage media, flash-memory devices, and other storage devices and media. In these embodiments, one or more processors of the UE 800 may be configured with the instructions to perform the operations described herein.
In some embodiments, the UE 800 may be configured to receive OFDM communication signals over a multicarrier communication channel in accordance with an OFDMA communication technique. The OFDM signals may comprise a plurality of orthogonal subcarriers. In some broadband multicarrier embodiments, eNBs (including macro eNB and pico eNBs) may be part of a broadband wireless access (BWA) network communication network, such as a Worldwide Interoperability for Microwave Access (WiMAX) communication network or a 3rd Generation Partnership Project (3GPP) Universal Terrestrial Radio Access Network (UTRAN) Long-Term-Evolution (LTE) or a Long-Term-Evolution (LTE) communication network, although the scope of the inventive subject matter described herein is not limited in this respect. In these broadband multicarrier embodiments, the UE 800 and the eNBs may be configured to communicate in accordance with an orthogonal frequency division multiple access (OFDMA) technique. The UTRAN LTE standards include the 3rd Generation Partnership Project (3GPP) standards for UTRAN-LTE, release 8, March 2008, and release 10, December 2010, including variations and evolutions thereof.
In some LTE embodiments, the basic unit of the wireless resource is the Physical Resource Block (PRB). The PRB may comprise 12 sub-carriers in the frequency domain×0.5 ms in the time domain. The PRBs may be allocated in pairs (in the time domain). In these embodiments, the PRB may comprise a plurality of resource elements (REs). A RE may comprise one sub-carrier×one symbol.
Two types of reference signals may be transmitted by an eNB including demodulation reference signals (DM-RS), channel state information reference signals (CIS-RS) and/or a common reference signal (CRS). The DM-RS may be used by the UE for data demodulation. The reference signals may be transmitted in predetermined PRBs.
In some embodiments, the OFDMA technique may be either a frequency domain duplexing (FDD) technique that uses different uplink and downlink spectrum or a time-domain duplexing (TDD) technique that uses the same spectrum for uplink and downlink.
In some other embodiments, the UE 800 and the eNBs may be configured to communicate signals that were transmitted using one or more other modulation techniques such as spread spectrum modulation (e.g., direct sequence code division multiple access (DS-CDMA) and/or frequency hopping code division multiple access (FH-CDMA)), time-division multiplexing (TDM) modulation, and/or frequency-division multiplexing (FDM) modulation, although the scope of the embodiments is not limited in this respect.
In some embodiments, the UE 800 may be part of a portable wireless communication device, such as a PDA, a laptop or portable computer with wireless communication capability, a web tablet, a wireless telephone, a wireless headset, a pager, an instant messaging device, a digital camera, an access point, a television, a medical device (e.g., a heart rate monitor, a blood pressure monitor, etc.), or other device that may receive and/or transmit information wirelessly.
In some LTE embodiments, the UE 800 may calculate several different feedback values which may be used to perform channel adaption for closed-loop spatial multiplexing transmission mode. These feedback values may include a channel-quality indicator (CQI), a rank indicator (RI) and a precoding matrix indicator (PMI). By the CQI, the transmitter selects one of several modulation alphabets and code rate combinations. The RI informs the transmitter about the number of useful transmission layers for the current MIMO channel, and the PMI indicates the codebook index of the precoding matrix (depending on the number of transmit antennas) that is applied at the transmitter. The code rate used by the eNB may be based on the CQI. The PMI may be a vector that is calculated by the UE and reported to the eNB. In some embodiments, the UE may transmit a physical uplink control channel (PUCCH) of format 2, 2a or 2b containing the CQI/PMI or RI.
In these embodiments, the CQI may be an indication of the downlink mobile radio channel quality as experienced by the UE 800. The CQI allows the UE 800 to propose to an eNB an optimum modulation scheme and coding rate to use for a given radio link quality so that the resulting transport block error rate would not exceed a certain value, such as 10%. In some embodiments, the UE may report a wideband CQI value which refers to the channel quality of the system bandwidth. The UE may also report a sub-band CQI value per sub-band of a certain number of resource blocks which may be configured by higher layers. The full set of sub-bands may cover the system bandwidth. In case of spatial multiplexing, a CQI per code word may be reported.
In some embodiments, the PMI may indicate an optimum precoding matrix to be used by the eNB for a given radio condition. The PMI value refers to the codebook table. The network configures the number of resource blocks that are represented by a PMI report. In some embodiments, to cover the system bandwidth, multiple PMI reports may be provided. PMI reports may also be provided for closed loop spatial multiplexing, multi-user MIMO and closed-loop rank 1 precoding MIMO modes.
In some cooperating multipoint (CoMP) embodiments, the network may be configured for joint transmissions to a UE in which two or more cooperating/coordinating points, such as remote-radio heads (RRHs) transmit jointly. In these embodiments, the joint transmissions may be MIMO transmissions and the cooperating points are configured to perform joint beamforming.
The example embodiments discussed herein may be utilized by wireless network access providers of all types including, but not limited to, mobile broadband providers looking to increase cellular offload ratios for cost-avoidance and performance gains, fixed broadband providers looking to extend their coverage footprint outside of customers' homes or businesses, wireless network access providers looking to monetize access networks via access consumers or venue owners, public venues looking to provide wireless network (e.g., Internet) access, or digital services (e.g. location services, advertisements, entertainment, etc.) over a wireless network, and business, educational or non-profit enterprises that desire to simplify guest Internet access or Bring-Your-Own-Device (BYOD) access.
This patent application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/862,686, entitled “ACCESS POINT INFORMATION DATA STRUCTURE,” filed on Aug. 6, 2013, (Attorney Docket No. 884.P01PRV), which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61862686 | Aug 2013 | US |
