Wireless signal identification

Technologies are generally described for identifying whether a propagation path between a mobile device and an access point is line-of-sight. In some examples, a method performed under control of a mobile device may include receiving, from an access point, a first signal transmitted at a first frequency band; receiving, from the access point, a second signal transmitted at a second frequency band; measuring a difference value between propagation properties of the first signal and the second signal; and identifying whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value.

CROSS-REFERENCE TO RELATED APPLICATION

This Application is the U.S. National Stage filing under 35 U.S.C. § 371 of International Application No. PCT/US14/36080, filed on Apr. 30, 2014. The disclosure of the International Application is hereby incorporated herein by reference in its entirety.

BACKGROUND

Location estimation in wireless technology has attracted great interests in recent research, because it is an important task in various applications of wireless communications. Further, attention on developing an indoor location technology based on the wireless local area network (WLAN) is gradually increasing while the population of the WLAN is growing. The superiority in using this technique can utilize the existing hardware without affecting the original network access function, and will also create a popular value added.

SUMMARY

In an example, a method performed under control of a mobile device may include receiving, from an access point, a first signal transmitted at a first frequency band; receiving, from the access point, a second signal transmitted at a second frequency band; measuring a difference value between propagation properties of the first signal and the second signal; and identifying whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value.

In another example, a mobile device may include a receiver unit configured to receive, from an access point, a first signal transmitted at a first frequency band and a second signal transmitted at a second frequency band; a difference value calculation unit configured to calculate a difference value between propagation properties of the first signal and the second signal; an identification unit configured to identify whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value; and a position calculation unit configured to calculate a current position of the mobile device based at least in part on the first signal and/or the second signal.

In yet another example, a computer-readable storage medium may store thereon computer-executable instructions that, in response to execution, cause a mobile device to perform operations, including transmitting, to an access point, a probe request signal at a first frequency band; receiving, from the access point, a probe response signal transmitted at the first frequency band in response to the probe request signal; receiving, from the access point, a beacon signal transmitted at a second frequency band; measuring a difference value between propagation properties of the probe response signal and the beacon signal; and identifying whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value.

DETAILED DESCRIPTION

This disclosure is generally drawn, inter alia, to methods, apparatuses, systems, devices, and computer program products related to identify a wireless signal from an access point. Further, technologies are herein generally described for identifying whether a propagation path between a mobile device and an access point is line-of-sight or non-line-of-sight based on properties of multiple signals each transmitted, from the access point, at a different frequency band to provide more accurate position information of the mobile device.

In some examples, a mobile device may be configured to receive, from an access point, a first signal and a second signal respectively transmitted at a first frequency band and a second frequency band. In such cases, propagation properties of the first frequency band and the second frequency band may be different. By way of example, but not limitation, the first frequency band may be an industry-science-medical (ISM) band of about 2.4 GHz and the second frequency band may be a unlicensed national information infrastructure (UNII) band of about 5 GHz. By way of non-limiting example, the propagation property may include, but not limited thereto, a propagation loss, a reflection property, a diffraction property or an absorption property.

The mobile device may be configured to measure a difference value between the propagation properties of the first signal and the second signal. Further, the mobile device may be configured to identify whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value. By way of example, but not limitation, a difference value of propagation losses between the ISM band and the UNII band is normally about 6.8 dB. However, the difference value may be higher than the normal value when there are obstacles (such as, for example, walls, furniture, etc.) between the mobile device and the access point (that is, the propagation path between the mobile device and the access point is non-line-of-sight). The mobile device may determine that the propagation path between the mobile device and the access point is non-line-of-sight when the difference value is higher than the normal value.

In some examples, the mobile device may be further configured to receive, from the access point, a propagation environment signal, which may include, for example, at least one of information about a layout of a building, in which the access point and the mobile device are located, or information about materials of the building. In such cases, the mobile device may be further configured to identify whether the propagation path is line-of-sight or non-line-of-sight based on the propagation environment signal.

In some examples, the first signal and/or the second signal transmitted from the access point may include location information of the access point, and the mobile device may be configured to calculate a current position of the mobile device based on the location information of the access point. Further, the mobile device may use the location information to calculate the current position of the mobile device only when the propagation path is identified as being line-of-sight. By way of example, but not limitation, the mobile device may receive signals from multiple access points (including the access point) and calculate the current position of the mobile device using triangulation based on respective location information of the multiple access points.

FIG. 1shows an illustrative example of a wireless communication environment100including a mobile device110and an access point120, arranged in accordance with at least some embodiments described herein. For example, but not as a limitation, mobile device110may refer to at least one of a smart phone, a portable device, a notebook computer, a tablet device, a phablet device, a personal computer or a personal communication terminal, such as PCS (Personal Communication System), GMS (Global System for Mobile communications), PDC (Personal Digital Cellular), or PDA (Personal Digital Assistant).

Access point120may be configured to provide wireless communication capability to one or more devices, including mobile device110, located within its communication range. Access point120may be configured to transmit, to mobile device110, a first signal130at a first frequency band. Further, access point120may be configured to transmit, to mobile device110, a second signal140at a second frequency band that is different from the first frequency band. In some embodiments, access point120may receive a probe request signal from mobile device110and, in response to the probe request signal, transmit, to mobile device110, first signal130(which may be a probe response signal) at the first frequency band. In the present disclosure, it is assumed that a propagation property (such as, for example, a propagation loss, a reflection property, a diffraction property or an absorption property) of the first frequency band is different from that of the second frequency band.

In some embodiments, mobile device110may be configured to receive first signal130at the first frequency band and second signal140at the second frequency band. Mobile device110may be configured to measure a propagation property of first signal130and that of second signal140and measure a difference value between propagation properties of first signal130and second signal140. Mobile device110may then be configured to identify whether a propagation path between mobile device110and access point120is line-of-sight or non-line-of-sight based on the measured difference value. In some embodiments, mobile device110may compare the measured difference value with a normal difference value of free-space propagation. In such cases, when the measured difference value is higher than the normal difference value of free-space propagation, mobile device110may determine that the propagation path between mobile device110and access point120is non-line-of-sight.

By way of non-limiting example, access point120may include a wireless-fidelity (Wi-Fi) access point based on IEEE 802.11a/b/g/n/ac. Such Wi-Fi access point is capable to use an ISM band and a UNII band to perform wireless communication. Available frequency resources at the Wi-Fi access point may include fourteen (14) channels at the ISM band (2.412 to 2.472 GHz; represented by 2.4 GHz) and twenty four (24) channels at the UNII band (5.180 to 5.825 GHz; represented by 5 GHz). In such examples, the first frequency band may correspond to the ISM band and the second frequency band may correspond to the UNII band. Further, mobile device110may be equipped with a Wi-Fi chipset, which can provide wireless communication capability at both of the ISM band and the UNII band, so that mobile device110may be able to perform wireless communication with access point120through both of the ISM band and the UNII band.

Propagation properties in the ISM band and the UNII band may have inherent characteristics due to the difference in frequency bands, as below. For example, the difference of propagation losses between 2.4 GHz and the 5 GHz is normally around 6.8 dB. If the difference of propagation losses is over 15 dB, mobile device110may determine that the propagation path between mobile device110and access point120is non-line-of-sight.

In some embodiments, mobile device110may be configured to concurrently receive first signal130at the first frequency band and second signal140at the second frequency band. In some other embodiments, mobile device110may perform an active scanning (for example, transmitting a probe request signal to access point120) at the first frequency and receive first signal130(for example, a probe response signal) from access point120. In such cases, mobile device110may then perform a passive scanning (for example, receiving a beacon signal from access point120) at the second frequency band.

In some embodiments, at least one of first signal130or second signal140may be configured to include location information of access point120. Mobile device110, which has received first signal130and second signal140, may calculate a current position of mobile device110using the location information of access point120together with location information of one or more other access points. By way of example, but not limitation, mobile device110may calculate the current position using triangulation based on respective location information of the multiple access points. In some embodiments, mobile device110may be configured to calculate the current position based only on access points that are located in a line-of-sight path. That is, when mobile device110determines that the propagation path between mobile device110and access point120is non-line-of-sight, mobile device110may not use the location information of access point120to calculate the current position of mobile device110.

In some examples, mobile device110may be configured to receive a propagation environment signal from access point120. In the examples of using the ISM band and the UNII band, mobile device110may receive the propagation environment signal at the ISM band. By way of example, but not limitation, the propagation environment signal may include at least one of information about a layout of a building, in which mobile device110and access point120are located, or information about materials of the building. In such cases, mobile device110may be further configured to identify whether the propagation path is line-of-sight or non-line-of-sight based on the propagation environment signal.

FIG. 2shows a block diagram of an example architecture of mobile device110configured to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein. Reference may be made to the embodiments depicted and described with reference toFIG. 1.

As depicted, mobile device110may include a receiver unit210, a difference value calculation unit220, an identification unit230and a position calculation unit240. Although illustrated as discrete components, various components may be divided into additional components, combined into fewer components, or eliminated while being contemplated within the scope of the disclosed subject matter. It will be understood by those skilled in the art that each function and/or operation of the components may be implemented, individually and/or collectively, by a wide range of hardware, software, firmware, or virtually any combination thereof.

Receiver unit210may be configured to receive, from access point110, first signal130at the first frequency band and second signal140at the second frequency band. In some embodiments, receiver unit210may receive first signal130and second signal140concurrently. In some embodiments, receiver unit210may receive first signal130first and then second signal140later. By way of example, the first frequency band may be an ISM band of 2.4 GHz and the second frequency band may be a UNII band of 5 GHz. In some embodiments, receiver unit may be further configured to receive a propagation environment signal from access point120. The propagation environment signal may be received at the first frequency band. By way of example, but not limitation, the propagation environment signal may include at least one of information about a layout of a building, in which mobile device110and access point120are located, or information about materials of the building.

Difference value calculation unit220may be configured to measure a propagation property of first signal130and that of second signal140and calculate a difference value between propagation properties of first signal130and second signal140. By way of example, but not limitation, the propagation property may include a propagation loss, a reflection property, a diffraction property or an absorption property.

Identification unit230may be configured to identify whether a propagation path between mobile device110and access point120is line-of-sight or non-line-of-sight based on the calculated difference value. In some embodiments, identification unit230may compare the calculated difference value with a normal difference value of free-space propagation. In such cases, when the calculated difference value is higher than the normal difference value of free-space propagation, identification unit230may determine that the propagation path between mobile device110and access point120is non-line-of-sight. In some embodiments, identification unit230may further make a reference to the propagation environment signal received by receiver unit210for the determination, and such reference may contribute to a more precise determination.

Position calculation unit240may be configured to calculate a current position of mobile device110based at least in part on first signal130and/or second signal140. In such cases, at least one of first signal130or second signal140may include location information of access point120. By way of example, but not limitation, mobile device110may calculate the current position using triangulation based on respective location information of multiple access points including access point120. In some embodiments, position calculation unit240may be configured to calculate the current position based only on access points that are located in a line-of-sight path. That is, when identification unit230determines that the propagation path between mobile device110and access point120is non-line-of-sight, position calculation unit240may not use the location information of access point120to calculate the current position of mobile device110.

FIG. 3shows a block diagram of another example architecture of mobile device110configured to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein. Reference may be made to the embodiments depicted and described with reference toFIGS. 1 and 2.

As depicted, mobile device110may include a signal identification manager310, an operating system320and a processor330. Signal identification manager310may be adapted to operate on operating system320such that the wireless signal identification scheme, as described herein, may be provided. Operating system320may allow signal identification manager310to manipulate processor330to implement the wireless signal identification scheme as described herein.

FIG. 4shows a block diagram of an example architecture of signal identification manager310to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein. Reference may be made to the embodiments depicted and described with reference toFIGS. 1 to 3.

As depicted, signal identification manager310may include a difference value calculation component410and an identification component420. Difference value calculation component410may be adapted to calculate a difference value between propagation properties of first signal130and second signal140, in accordance with various example methods as described above. Identification component420may be adapted to identify whether a propagation path between mobile device110and access point120is line-of-sight or non-line-of-sight based at least in part on the calculated difference value, in accordance with various example methods as described above.

FIG. 5shows an illustrative example of an indoor place in which a mobile device510and multiple access points521,522,523,524and525are located, arranged in accordance with at least some embodiments described herein.

As depicted, access points521to525are located in various positions in the indoor place, in which a hallway wall530, a room540and a block550are arranged to divide the indoor place. Mobile device510, which is located in the indoor place, may receive signals from access points521to525.

In some embodiments, mobile device510may receive a first signal at a first frequency band and a second signal at a second frequency band from each of access points521to525. The first signal and the second signal may be received at mobile device510concurrently or sequentially. Mobile device510may then measure and/or calculate a difference value between propagation properties of the first signal and the second signal for each of access points521to525and identify whether each propagation path between mobile device510and each of access points521to525is line-of-sight or non-line-of-sight based on corresponding difference value.

As depicted inFIG. 5, there are no obstacles between mobile device510and access points521to523, and thus, it may be determined that the propagation paths between mobile device510and access points521to523are line-of-sight. However, access points524and525are blocked by hallway wall530and room540, respectively, and the propagation paths between mobile device510and access points524and525are non-line-of-sight. In some embodiments, mobile device510may receive location information from each of access points521to523, of which the propagation path is line-of-sight, to calculate a current position of mobile device510using triangulation based the received location information.

FIG. 6shows an example flow diagram of a process to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein.

Process600may be implemented by a mobile device such as mobile device110including at least some of receiver unit210, difference value calculation unit220, identification unit230or position calculation unit240. Process600may also be implemented by computer programs or program modules that may be adapted to provide a wireless signal identification scheme and hosted by mobile device110, such as signal identification manager310including difference value calculation component410and identification component420. Thus, reference may be made to the embodiments depicted and described with reference toFIGS. 1-5. Process600may include one or more operations, actions, or functions as illustrated by one or more blocks610,620,630and/or640. Although illustrated as discrete blocks, various blocks may be divided into additional blocks, combined into fewer blocks, or eliminated, depending on the desired implementation. Processing may begin at block610.

At block610(Receive a First Signal Transmitted at a First Frequency Band), mobile device110and/or receiver unit210may receive, from access point120, first signal130at the first frequency band. By way of example, but not limitation, the first frequency band may be an ISM band. Processing may continue from block610to block620.

At block620(Receive a Second Signal Transmitted at a Second Frequency Band), mobile device110and/or receiver unit210may receive, from access point120, second signal140at the second frequency band. By way of example, but not limitation, the second frequency band may be a UNII band. Processing may continue from block620to block630.

At block630(Calculate a Difference Value between Propagation Properties of the First and Second Signals), mobile device110and/or difference value calculation unit220may measure a propagation property of first signal130and that of second signal140. Then, mobile device110and/or difference value calculation unit220may measure and/or calculate a difference value between the propagation properties of first signal130and second signal140. By way of non-limiting example, the propagation property may include, but not limited thereto, a propagation loss, a reflection property, a diffraction property or an absorption property. Processing may continue from block630to block640.

At block640(Identify Whether a Propagation Path is Line-of-Sight), mobile device110and/or identification unit230may identify whether a propagation path between mobile device110and access point120is line-of-sight or non-line-of-sight based on the difference value. In some embodiments, mobile device110and/or identification unit230may compare the difference value with a normal difference value of free-space propagation. In such cases, when the difference value is within a predetermined range of the normal difference value of free-space propagation, mobile device110and/or identification unit230may determine that the propagation path between mobile device110and access point120is line-of-sight.

FIG. 7illustrates an example computer program product700that may be utilized to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein.

As depicted, program product700may include a signal bearing medium702. Signal bearing medium702may include one or more instructions704that, when executed by, for example, a processor of mobile device110may provide the functionality described above with respect toFIGS. 1-6. By way of example, instructions704may include: one or more instructions for receiving, from an access point, a first signal transmitted at a first frequency band; or one or more instructions for receiving, from the access point, a second signal transmitted at a second frequency band; or one or more instructions for calculating (and/or measuring) a difference value between propagation properties of the first signal and the second signal; or one or more instructions for identifying whether a propagation path between the mobile device and the access point is line-of-sight or non-line-of-sight based at least in part on the difference value.

In some implementations, signal bearing medium702may encompass a computer-readable medium706, such as, but not limited to, a hard disk drive, a CD, a DVD, a digital tape, memory, etc. In some implementations, signal bearing medium702may encompass a recordable medium708, such as, but not limited to, memory, read/write (R/W) CDs, R/W DVDs, etc. In some implementations, signal bearing medium702may encompass a communications medium710, such as, but not limited to, a digital and/or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link, etc.). Thus, for example, program product700may be conveyed to one or more modules of electronic device120by an RF signal bearing medium702, where the signal bearing medium702is conveyed by a wireless communications medium710(e.g., a wireless communications medium conforming with the IEEE 802.11 standard).

FIG. 8is a block diagram illustrating an example computing device800that may be utilized to implement a wireless signal identification scheme, arranged in accordance with at least some embodiments described herein.

In a very basic configuration802, computing device800typically includes one or more processors804and a system memory806. A memory bus808may be used for communicating between processor804and system memory806.

Depending on the desired configuration, processor804may be of any type including but not limited to a microprocessor (μP), a microcontroller (μC), a digital signal processor (DSP), or any combination thereof. Processor804may include one or more levels of caching, such as a level one cache810and a level two cache812, a processor core814, and registers816. An example processor core814may include an arithmetic logic unit (ALU), a floating point unit (FPU), a digital signal processing core (DSP Core), or any combination thereof. An example memory controller818may also be used with processor804, or in some implementations memory controller818may be an internal part of processor804.

Depending on the desired configuration, system memory806may be of any type including but not limited to volatile memory (such as RAM), nonvolatile memory (such as ROM, flash memory, etc.) or any combination thereof. System memory806may include an operating system820, one or more applications822, and program data824.

Application822may include an signal identification algorithm826that may be arranged to perform the functions as described herein including the actions described with respect to mobile device110architecture as shown inFIGS. 2-4or including the actions described with respect to the flow chart shown inFIG. 6. Program data824may include any data that may be useful for providing the signal identification scheme as is described herein. In some examples, application822may be arranged to operate with program data824on an operating system820such that the wireless signal identification scheme as described herein may be provided.

Computing device800may have additional features or functionality, and additional interfaces to facilitate communications between basic configuration802and any required devices and interfaces. For example, a bus/interface controller830may be used to facilitate communications between basic configuration802and one or more data storage devices832via a storage interface bus834. Data storage devices832may be removable storage devices836, non-removable storage devices838, or a combination thereof. Examples of removable storage and non-removable storage devices include magnetic disk devices such as flexible disk drives and hard-disk drives (HDD), optical disk drives such as compact disk (CD) drives or digital versatile disk (DVD) drives, solid state drives (SSD), and tape drives to name a few. Example computer storage media may include volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information, such as computer readable instructions, data structures, program modules, or other data.

System memory806, removable storage devices836and non-removable storage devices838are examples of computer storage media. Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which may be used to store the desired information and which may be accessed by computing device800. Any such computer storage media may be part of computing device800.

Computing device800may also include an interface bus840for facilitating communication from various interface devices (e.g., output devices842, peripheral interfaces844, and communication devices846) to basic configuration802via bus/interface controller830. Example output devices842include a graphics processing unit848and an audio processing unit850, which may be configured to communicate to various external devices such as a display or speakers via one or more A/V ports852. Example peripheral interfaces844include a serial interface controller854or a parallel interface controller856, which may be configured to communicate with external devices such as input devices (e.g., keyboard, mouse, pen, voice input device, touch input device, etc.) or other peripheral devices (e.g., printer, scanner, etc.) via one or more I/O ports858. An example communication device846includes a network controller860, which may be arranged to facilitate communications with one or more other computing devices862over a network communication link via one or more communication ports864.