Antenna array with selectable horizontal, vertical or circular polarization

Abstract

A system and method for selecting polarization for a particular antenna in an antenna array are disclosed. The system includes an antenna array, where each antenna is adapted to receive and transmit horizontally and vertically polarized signals. The system also includes a switching network that is adapted to select either a vertical or a horizontal polarized signal for each antenna in the antenna array. The switching network also allows selection of circularly polarized signals from one or more antenna elements in the antenna array. This allows AoX to be more accurate as it is able to receive both horizontally and vertically polarized signals rather than just circularly polarized signals, thus improving its accuracy. The ability to receive circularly polarized signals during a reference period may help in obtaining appropriate gain and frequency.

Description

Technical Field

[0001] The present disclosure describes systems and methods for selecting a specific polarization for antennas in an antenna array. Background Art

[0002] Angle-of-arrival and angle-of-departure algorithms, collectively referred to as AoX algorithms, typically operate by determining the phase difference between different antenna elements in an antenna array. This phase difference can be used to determine the angle from which a signal originates, since the distance between the antenna elements is known.

[0003] Specifically, assume that the distance between two adjacent antenna elements is d. The phase difference between the detection times of an input signal at these two adjacent antenna elements can be expressed as This phase difference Divided by 2π multiplied by the wavelength λ represents the distance between the two antenna elements as observed from the signal source. Knowing the difference in the propagation distances of the input signal allows the calculation of the angle of arrival. Specifically, the angle of arrival can be given by dividing the difference in the propagation distances of the input signal by d, which represents the cosine of the input signal. In other words, the angle of arrival is defined as The arccosine of.

[0004] One algorithm commonly used to determine AoX is called MUSIC. This algorithm generates a pseudo-spectrum from the input data and estimates the most likely AoX from these pseudo-spectra. Many antenna arrays use circular polarization during the AoX algorithm. However, this method may result in larger errors than expected, especially in multipath environments.

[0005] Therefore, it would be beneficial if there were a system and method for determining a more accurate AoX than existing antenna arrays by using a dual-polarization reception method. Additionally, it would be advantageous to use circular polarization detection during the reference period of a data packet for more accurate receiver gain adjustment. Additionally, it would be advantageous if this system did not require any additional antenna elements to achieve this result. Summary of the Invention

[0006] Disclosed is a system and method for selecting a polarization for a specific antenna element in an antenna array. The system includes an antenna array, where each antenna element is adapted to receive and transmit horizontally and vertically polarized signals. The system also includes a switching network that is adapted to select a vertical or horizontal polarization signal for each antenna element in the antenna array. The switching network also allows the selection of circularly polarized signals from one or more antenna elements in the antenna array. This allows for a more accurate AoX, as it is able to receive horizontally and vertically polarized signals, rather than just circularly polarized signals, thereby improving its accuracy. The ability to receive circularly polarized signals during the reference period may help in obtaining appropriate gain and frequency.

[0007] According to one embodiment, a wireless network device is disclosed. The wireless network device includes an antenna array including a plurality of antenna elements; a wireless network interface, wherein the wireless network interface receives an input signal from one of the antenna elements in the antenna array; a processing unit; and a switching network disposed between the antenna array and the wireless network interface to select an antenna element from the antenna array, wherein the switching network is configured to couple a horizontally polarized signal or a vertically polarized signal from any one of the plurality of antenna elements to the wireless network interface, and the switching network is further configured to couple a circularly polarized signal from at least one of the antenna elements to the wireless network interface. In some embodiments, the wireless network device receives a signal including a constant tone extension (CTE) having a plurality of switching time slots and sampling time slots. In certain embodiments, the processing unit includes a plurality of output signals communicating with the switching network; wherein the processing unit selects one of the plurality of antenna elements during each switching time slot by modifying the plurality of output signals. In some embodiments, the CTE further includes a guard period and a reference period, wherein the processing unit modifies the plurality of output signals to receive a circularly polarized signal during at least a portion of the guard period and / or the reference period. In certain embodiments, the wireless network interface includes a programmable gain amplifier (PGA), and the processing unit sets the gain of the PGA based on the amplitude of the circularly polarized signal received during at least a portion of the guard period and / or the reference period. In certain embodiments, the wireless network interface includes a low noise amplifier (LNA), and the processing unit sets the gain of the LNA based on the amplitude of the circularly polarized signal received during the reference period. In some embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and the antenna elements disposed along the outer edge of the N×M array are used to provide circularly polarized signals. In some embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and the internal antenna elements are used to provide circularly polarized signals.

[0008] According to another embodiment, a switching network communicating with an antenna array is disclosed, wherein each antenna element in the antenna array includes a horizontally polarized signal and a vertically polarized signal. The switching network includes: an upper antenna selection switch and a lower antenna selection switch, an upper polarization switch, a lower polarization switch, a 90° hybrid, a bank selection switch, and a main polarization switch. The upper antenna selection switch and the lower antenna selection switch each have a multiplexed signal and a plurality of demultiplexed signals, wherein the horizontally polarized signal and the vertically polarized signal of each antenna element communicate with the demultiplexed signals on one of the upper antenna selection switch and the lower antenna selection switch; wherein, the vertically polarized signal and the horizontally polarized signal of at least one antenna element communicate with the demultiplexed signals on different antenna selection switches, and a control signal called ANTENNA SELECT is used to select one of the demultiplexed signals to communicate with the multiplexed signal; the upper polarization switch has a multiplexed signal communicating with the multiplexed signal from the upper antenna selection switch, and the upper polarization switch has a first demultiplexed signal and a second demultiplexed signal, and a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal; the lower polarization switch has a multiplexed signal communicating with the multiplexed signal from the lower antenna selection switch, and the lower polarization switch has a first multiplexed signal and a second demultiplexed signal, and a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal; the 90° hybrid communicates with the second demultiplexed signal from the upper polarization switch and the second demultiplexed signal from the lower polarization switch; the bank selection switch has a multiplexed signal, a first demultiplexed signal communicating with the first demultiplexed signal from the upper polarization switch, and a second demultiplexed signal communicating with the first demultiplexed signal from the lower polarization switch, and a control signal called UPPER / LOWER is used to select one of the demultiplexed signals to communicate with the multiplexed signal; the main polarization switch has a multiplexed signal, a first demultiplexed signal communicating with the multiplexed signal from the bank selection switch, and a second demultiplexed signal communicating with the 90° hybrid, and a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal. In some embodiments, the vertically polarized signal and the horizontally polarized signal of at least two antenna elements communicate with the demultiplexed signals on different antenna selection switches. In certain embodiments, the upper antenna selection switch and the lower antenna selection switch each include 16 demultiplexed signals, and the antenna array includes 16 antenna elements. In some embodiments, the switching network includes a third antenna selection switch and a fourth antenna selection switch; wherein the bank selection switch includes: a third demultiplexed signal communicating with the multiplexed signal from the third antenna selection switch; a fourth demultiplexed signal communicating with the multiplexed signal from the fourth antenna selection switch; and an additional control signal selected from the four demultiplexed signals.In some embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and where at least one of the antenna elements is an internal antenna element. In some embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and where at least one of the antenna elements is disposed along an outer edge of the antenna array. In certain embodiments, the switching network is adapted to send signals to or receive signals from the antenna array.

[0009] According to another embodiment, a method for calculating an angle of arrival is disclosed. The method includes: receiving, at a wireless network device, a signal including a constant tone extension having a guard period, a reference period, and a plurality of switching time slots and sampling time slots, where the wireless network device includes an antenna array and a switching network, the antenna array including a plurality of antenna elements, the switching network selecting among signals from the antenna array; configuring the switching network to receive a circularly polarized signal from one of the plurality of antenna elements; receiving the circularly polarized signal during at least a portion of the guard period and / or the reference period; configuring the switching network to receive a horizontally polarized signal from a first one of the plurality of antenna elements during a switching time slot; receiving the horizontally polarized signal from the first one of the plurality of antenna elements during a sampling time slot; configuring the switching network to receive a vertically polarized signal from the first one of the plurality of antenna elements during a switching time slot; receiving the vertically polarized signal from the first one of the plurality of antenna elements during a sampling time slot; repeating the configuring and receiving to receive vertically polarized signals and horizontally polarized signals from all of the antenna elements in the antenna array; using information from the horizontally polarized signals and the vertically polarized signals to calculate the angle of arrival. In some embodiments, the method includes using information from the circularly polarized signal to set a gain of a programmable gain amplifier (PGA). In certain embodiments, the method includes using information from the circularly polarized signal to set a gain of a low noise amplifier (LNA). In some embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and the circularly polarized signal is received from an internal antenna element. In certain embodiments, the antenna array includes an N×M array, where both N and M are greater than 1, and the circularly polarized signal is received from an antenna element disposed along an outer edge of the antenna array. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] To better understand the present disclosure, reference is made to the accompanying drawings, where like elements are denoted by like reference numerals, and where:

[0011] Figure 1 is a block diagram of a network device that can be used to perform the methods described herein;

[0012] Figure 2 is Figure 1 a block diagram of a radio receiver of the network device of

[0013] Figures 3A - 3C shows a transmission toFigure 1 Format of a representative direction detection message of the system;

[0014] Figure 4 Shows a block diagram of a handover network according to an embodiment;

[0015] Figure 5 Shows various outputs that can be achieved using Figure 4 the handover network; and

[0016] Figure 6 Shows a flowchart describing the operation of a network device. DETAILED DESCRIPTION

[0017] Figure 1 Shows a network device that can be used to execute the AoX algorithm described herein. The network device 10 has a processing unit 20 and an associated memory device 25. The processing unit 20 can be any suitable component, such as a microprocessor, an embedded processor, an application-specific circuit, a programmable circuit, a microcontroller, or other similar devices. The memory device 25 contains instructions that, when executed by the processing unit 20, enable the network device 10 to perform the functions described herein. The memory device 25 can be a non-volatile memory, such as FLASH ROM, electrically erasable ROM, or other suitable devices. In other embodiments, the memory device 25 can be a volatile memory, such as RAM or DRAM. The instructions contained in the memory device 25 can be referred to as a software program, which is set on a non-transitory storage medium.

[0018] The network device 10 further includes a network interface 30, which can be a wireless network interface including an antenna array 38. The network interface 30 can support any wireless network protocol that supports AoX determination, such as Bluetooth. The network interface 30 is used to allow the network device 10 to communicate with other devices disposed on the network 39.

[0019] The network interface 30 includes a radio circuit 31. The radio circuit 31 is used to process input signals and convert wireless signals into digital signals. The components within the radio circuit 31 are described in more detail below.

[0020] The network interface 30 further includes a read channel 36. The read channel 36 is used to receive, synchronize, and decode the digital signals received from the radio circuit 31. Specifically, the read channel 36 has a preamble detector for identifying the start of an input data packet. The read channel 36 also has a synchronization detector for identifying a specific bit sequence known as a synchronization character. In addition, the read channel 36 has a decoder for converting the digital signals into correctly aligned data bytes.

[0021] The network device 10 may include a second memory device 40. Data received from or to be transmitted via the network interface 30 may also be stored in the second memory device 40. This second memory device 40 is traditionally a volatile memory.

[0022] Although the memory device 25 is disclosed, any computer-readable medium may be employed to store these instructions. For example, a read-only memory (ROM), a random access memory (RAM), a magnetic storage device such as a hard disk drive, or an optical storage device such as a CD or DVD may be used. Additionally, these instructions may be downloaded into the memory device 25, for example, via a network connection (not shown), via a CD ROM, or by another mechanism. These instructions may be written in any programming language, without limitation to this disclosure. Thus, in some embodiments, there may be multiple computer-readable non-transitory media including the instructions described herein. As Figure 1 shown, a first computer-readable non-transitory medium may communicate with the processing unit 20. A second computer-readable non-transitory medium may be a CDROM or a different memory device located remotely from the network device 10. The instructions contained on this second computer-readable non-transitory medium may be downloaded onto the memory device 25 to allow the network device 10 to execute the instructions.

[0023] Although the processing unit 20, the memory device 25, the network interface 30, and the second memory device 40 are shown as separate components in Figure 1 it should be understood that some or all of these components may be integrated into a single electronic component. Instead, Figure 1 is used to illustrate the functionality of the network device 10 rather than its physical configuration.

[0024] Although not shown, the network device 10 also has a power source, which may be a battery or a connection to a permanent power source such as a wall socket.

[0025] Figure 2 A block diagram of the radio circuit 31 is shown. The wireless signal first enters the radio circuit 31 through one antenna element 37 of the antenna array 38. A switching network 50 may be used to select one antenna element 37 from the antenna array 38. Once selected, this antenna element 37 is in electrical communication with a low-noise amplifier (LNA) 51. The LNA 51 receives a very weak signal from the antenna element 37 and amplifies the signal while maintaining the signal-to-noise ratio (SNR) of the input signal. The amplified signal is then passed to a mixer 52. The mixer 52 also communicates with a local oscillator 53, which provides two phases to the mixer 52. The cosine of the frequency may be referred to as I o and the sine of the frequency may be referred to as Q o Then the I oThe signal is multiplied by the input signal to generate the in-phase signal I m . Then Q o The signal is multiplied by a 90° delayed version of the input signal to generate the quadrature signal Q m . Then the in-phase signal I from mixer 52 m and the quadrature signal Q m are fed into a programmable gain amplifier (PGA) 54. PGA 54 amplifies the I m signal and Q m signals by a programmable amount. These amplified signals are referred to as I g and Q g . Then the amplified signals I g and Q g are fed from PGA 54 into an analog-to-digital converter (ADC) 55. ADC 55 converts these analog signals into digital signals I d and Q d . These digital signals can pass through channel filter 56 and then leave radio circuit 31 as I and Q. In some embodiments, the I and Q values can be considered complex numbers, where the I value is the real part and the Q value is the imaginary part.

[0026] Then, the I and Q signals enter a CORDIC (Coordinated Rotation Digital Computer), which determines the magnitude and phase of the signals. The magnitude is given by the square root of I 2 and Q 2 , while the phase is given by tan -1 (Q / I). The CORDIC can be set within radio circuit 31 or elsewhere within network interface 30.

[0027] In some embodiments, network interface 30 operates on a wireless network that utilizes the Bluetooth network protocol. Figure 3A Shows the format of a special Bluetooth data packet for direction detection. These packets typically start with a preamble 300, an address field 310, a payload 320, and a checksum or CRC 330. However, the special packet also includes a Constant Tone Extension (CTE) 340. Figure 3B and Figure 3C Show two different formats of the CTE 340. In both formats, the CTE 340 includes a guard period 341, a reference period 342, and a plurality of switching time slots 343 and sampling time slots 344. The duration of each switching time slot 343 and sampling time slot 344 can be 1 μsec or 2 μsec, respectively, as shown in Figure 3B and Figure 3CAs shown. The CTE 340 is a special extension that sends Bluetooth data packets at a constant frequency (such as a 250 kHz tone). For example, the CTE 340 can be a string of consecutive "1"s. The CTE 340 can be as long as 160 μsec and as short as 16 μsec. In practice, the network device 10 can use a single antenna element 37 of the antenna array 38 to receive the CTE 340 during the guard period 341 and the reference period 342. The device uses the signals received during the guard period 341 and the reference period 342 to set the gain (AGC) and frequency (AFC) of the radio circuit 31. If circularly polarized signals from the antenna element 37 are used during the guard period 341 and the reference period 342, the determination of the gain and frequency of the radio circuit 31 may be more accurate.

[0028] Then, by changing the selection of the switching network 50 in the radio circuit 31, the network device 10 switches to another antenna element 37 during each switching time slot 343. The network device 10 samples the tone again using that new antenna element 37 during the sampling time slot 344. The network device 10 continues to switch the antenna element 37 during each switching time slot 343 and continues to sample the tone during the sampling time slot 344. If the number of switching time slots 343 is more than the number of antenna elements, the network device 10 returns to the first antenna element 37 and repeats the sequence.

[0029] During the entire CTE 340, the transmitting device sends the tone at a constant known frequency. As described above, the network device 10 can use one antenna element 37 of the antenna array 38 to receive the tone. Specifically, the same antenna element 37 can be used to receive the guard period 341 and the reference period 342 with a combined duration of 12 μsec.

[0030] Importantly, it has been found that the accuracy of the AoX algorithm is improved when the radio circuit 31 utilizes the horizontal and vertical polarization signals from each antenna element 37. Therefore, the radio circuit 31 selects each antenna element during at least two different sampling time slots 344: one for receiving the horizontal polarization signal and one for receiving the vertical polarization signal.

[0031] Therefore, in summary, to optimize the accuracy of the AoX algorithm, it may be beneficial to utilize the circularly polarized signal from one antenna element 37 during the guard period 341 and the reference period 342. It is also beneficial to sample each antenna element 37 at least twice during the sampling time slot 344 such that the horizontal and vertical polarization signals from each antenna element are used as part of the AoX algorithm.

[0032] This complex switching operation can be performed by the switching network 50. Figure 4A representative block diagram of the switching network 50 is shown. In this figure, it is assumed that there are 16 antenna elements 37, each configured to transmit and receive both horizontally and vertically polarized signals. In other words, the switching network is adapted to receive a signal from one of the antenna elements or transmit a signal to one of the antenna elements.

[0033] The upper antenna selection switch 450 is used to select one of the 16 antenna signals. In some embodiments, the signals for the upper antenna selection switch 450 may be based on printed circuit board routing considerations. For example, if the antenna array is arranged as a 4×4 array, most of the signals communicating with the upper antenna selection switch 450 may be from the antenna elements disposed in the top two rows of the antenna array 38. The lower antenna selection switch 460 is used to select one of the 16 antenna signals. Similarly, the signals for the lower antenna selection switch 460 may be based on printed circuit board routing considerations. For example, if the antenna array 38 is arranged as a 4×4 array, most of the signals communicating with the lower antenna selection switch 460 may be from the antenna elements disposed in the bottom two rows of the antenna array 38.

[0034] The upper antenna selection switch 450 and the lower antenna selection switch 460 may be bidirectional switches. Thus, these switches can be used to receive signals from the antenna elements 37 and also transmit signals to the antenna elements 37. Thus, depending on the direction of activity, the upper and lower antenna selection switches act as multiplexers and demultiplexers. For clarity, the side of the switch with multiple interfaces will be referred to as demultiplexing the signal, while the side of the switch with a single interface will be referred to as multiplexing the signal.

[0035] For most antenna elements, the horizontally polarized signal and the vertically polarized signal of each antenna element 37 can communicate with the demultiplexed signal on the same antenna selection switch (either the upper antenna selection switch 450 or the lower antenna selection switch 460). However, for at least one antenna element, the horizontally polarized signal and the vertically polarized signal communicate with the demultiplexed signals on different switches. In this particular illustration, the vertically polarized signal from antenna #6 communicates with the demultiplexed signal on the lower antenna selection switch 460, while the horizontally polarized signal communicates with the demultiplexed signal on the upper antenna selection switch 450. To accommodate this variation, the horizontally polarized signal from antenna #14 communicates with the demultiplexed signal on the upper antenna selection switch 450. Note that the signal from antenna #6 communicates with the demultiplexed signals labeled 10 on both switches. Similarly, the signal from antenna #14 communicates with the demultiplexed signals labeled 11 on both switches.

[0036] The specific antenna signal selected by these antenna selection switches is determined based on the selection signal. For example, four binary signals can be used to select one of the 16 demultiplexed signals on these switches. In some embodiments, these selection signals, referred to as ANTENNA SELECT, can be provided by the processing unit 20. For all switches described herein, control signals are used to allow one of the demultiplexed signals to communicate with the multiplexed signal.

[0037] Note that the upper antenna selection switch 450 and the lower antenna selection switch 460 have 16 inputs to accommodate two signals from each antenna element 37 in the antenna array 38. If there are a different number of antenna elements 37 in the antenna array 38, the upper antenna selection switch 450 and the lower antenna selection switch 460 can have a different number of inputs. For example, an antenna array arranged as a 4×2 array can utilize an upper antenna selection switch and a lower antenna selection switch each having 8 inputs.

[0038] The multiplexed signal from the upper antenna selection switch 450 communicates with the multiplexed signal from the upper polarization switch 430. The upper polarization switch 430 is used to select between a circularly polarized signal or a signal polarized in only one direction. Similarly, the multiplexed signal from the lower antenna selection switch 460 communicates with the multiplexed signal from the lower polarization switch 440. The lower polarization switch 440 is used to select between a circularly polarized signal or a signal polarized in only one direction. A signal referred to as CIRCULAR is used to select between these modes. This CIRCULAR signal can be provided by the processing unit 20.

[0039] The demultiplexed signals from the upper polarization switch and the lower polarization switch communicate with the 90° mixer 420 and the bank selector switch 410, respectively.

[0040] The bank selector switch 410 is used to select between the upper polarization switch 430 and the lower polarization switch 440. In some embodiments, a signal referred to as UPPER / LOWER is used to select between the two polarization switches. This UPPER / LOWER signal can be provided by the processing unit 20.

[0041] The 90° mixer 420 is configured to generate a circularly polarized signal on the left side when a horizontally polarized signal and a vertically polarized signal appear at two signals on the right side of the device. Similarly, if a circularly polarized signal appears on the left side of the device, a horizontally polarized signal and a vertically polarized signal are generated on the right side of the device.

[0042] The multiplexed signal from the library selector switch 410 communicates with the first demultiplexed signal from the main polarization switch 400. In addition, the 90° mixer 420 communicates with the second demultiplexed signal from the main polarization switch 400. As described above, the main polarization switch 400 is also controlled by the CIRCULAR signal.

[0043] Thus, in summary, the switching network uses six signals (the ANTENNA SELECT signal, the CIRCULAR signal, and the UPPER / LOWER signal) to select between the vertical polarization signal of any one of the 16 antenna elements, the horizontal polarization signal of any one of the 16 antenna elements, and the circular polarization signal of at least one of the antenna elements. Figure 5 The operation of the switching network 50 is shown.

[0044] Note that when CIRCULAR is set to zero, it is possible to select each of the 16 antenna elements in the horizontal or vertical polarization mode. In addition, when CIRCULAR is set to 1, it is possible to select antenna #6 or antenna #14 in the circular mode.

[0045] Therefore, by using a single 90° mixer and three additional switches (i.e., the main polarization switch 400, the upper polarization switch 430, and the lower polarization switch 440), it is possible to generate and receive at least one circular polarization signal from the antenna array 38. In addition, note that the circular polarization signal is generated from one or more antenna elements 37 in the antenna array 38, and no additional antennas separate from the antenna array 38 are required.

[0046] In addition, each signal from the antenna element 37 communicates with exactly one signal on the upper antenna selection switch 450 or the lower antenna selection switch 460. Thus, the length of each signal can be matched so that the phase delay associated with each antenna element is the same.

[0047] Note, Figure 4Only antennas #6 and #14 are allowed for circular polarization. However, the present disclosure is not limited to this embodiment. For example, if it is desired that four antenna elements need to operate in a circular polarization mode, the vertical polarization of the third antenna element can be moved from the upper antenna selection switch 450 to the lower antenna selection switch 460, and the vertical polarization of the third antenna element can be replaced by the horizontal polarization of the fourth antenna element in the lower antenna selection switch 460, and the polarization position of the fourth antenna element is located at the same position as the horizontal polarization of the third antenna element. For example, if the vertical polarization of antenna #1 is moved to the lower antenna selection switch 460, the horizontal polarization of antenna #9 will be used to replace it. In a particular embodiment, the horizontal polarization of all antenna elements communicates with the upper antenna selection switch 450, and the vertical polarization of all antenna elements communicates with the corresponding demultiplexed signals on the lower antenna selection switch 460. However, in some embodiments, the wiring of the signals from the antenna array 38 may make this configuration difficult to implement.

[0048] However, as described above, in many embodiments, a single antenna element is typically used to receive or transmit the guard period 341 and the reference period 342. Thus, as Figures 4 - 5 shown, the ability to obtain circular polarization for two antenna elements in the antenna array 38 is sufficient for this application.

[0049] In some embodiments, it may make sense to select which antenna elements are capable of circular polarization. For example, in some embodiments, in a 4×4 array, one of the four inner antenna elements may be preferred. In other embodiments, one of the four antenna elements located at the corners of the antenna array 38 may be preferred. By correctly selecting which antenna element is connected to which signal of the upper antenna selection switch 450 and the lower antenna selection switch 460, these configurations can be achieved. Thus, in some embodiments, the antenna array can be a 4×4 array, and at least one of antenna #14 or antenna #6 can be an antenna element disposed along the outer edge of the array, such as along one side of the outer side or at one of the corners. In some embodiments, at least one of antenna #14 or antenna #6 can be an antenna element that is one of the four inner antenna elements in the array. In another embodiment, one of antenna #14 or antenna #6 can be an antenna element disposed along the outer edge of the array, and the other of antenna #14 and antenna #6 can be an inner antenna element.

[0050] Although the above disclosure describes the antenna array as a 4×4 array, antenna arrays of any size can be utilized. For example, the antenna array can be an N×N array, where N is greater than 1. In other embodiments, the antenna array is not square and can be N×M, where both N and M are greater than 1.

[0051] In these embodiments, the antenna element 37 selected for circular polarization can be an internal antenna element or an antenna element disposed along the edge of the array.

[0052] In addition, if N (and M for non-square arrays) is less than 4, the upper antenna selection switch 450 and the lower antenna selection switch 460 can be used unchanged by retaining some unused demultiplexed signals. If N is greater than 4, the upper antenna selection switch 450 and the lower antenna selection switch 460 can be modified to include more than 16 demultiplexed signals.

[0053] Alternatively, additional antenna selection switches can be added. For example, the signals used by the antenna elements can be routed to 4 antenna selection switches, where the bank selector switch 410 is converted into a 4-to-1 switch.

[0054] For example, for a 6×6 array, 4 antenna selection switches can be used, where the first two antenna selection switches can be configured as shown, and two new antenna selection switches are used to communicate with the additional antenna elements. The multiplexed outputs from the two new antenna selection switches will be additional demultiplexed signals on the 4-to-1 bank selector switch 410. The 4-to-1 bank selector switch 410 can also have additional control signals to enable the 4-to-1 bank selector switch 410 to select among the four demultiplexed signals.

[0055] Based on this switching network 50, an order can be defined for receiving CTE. Figure 6 One such order is shown. First, as shown in block 600, the processing unit 20 can configure the switching network 50 to select the antenna element that supports circular polarization. In Figure 4 this case, this can be antenna #6 or antenna #14. This selection can be made using the values shown in Figure 5 . This antenna element is used to receive at least a portion of the guard period 341 and the reference period 342. Note that during these periods, the gains used by the LNA 51 and the PGA 54 are set based on the amplitude of the received circularly polarized signal.

[0056] The processing unit 20 waits for the reference period 342 to end, as shown in block 610. Once the reference period 342 ends, the processing unit 20 then cycles through each antenna element 37 in the antenna array 38 and samples the horizontal and vertical polarization signals from each antenna element 37. First, as shown in block 620, the processing unit 20 selects a particular antenna element 37 and polarization. Next, as shown in block 630, the device samples the polarization signal during the sampling time slot 344. During the next switching time slot 343, the processing unit 20 selects another antenna element 37 and / or polarization and repeats blocks 620 - 630 until the data packet is complete. At this point, the device has collected all the data needed and can calculate the angle of arrival, as shown in block 640.

[0057] Note that the order of the antenna elements 37 and polarizations is not limited by this disclosure. For example, in one embodiment, the processing unit may sample the same polarization for each antenna element 37 and then sample each antenna element with another polarization. In another embodiment, the processing unit 20 may select one antenna element 37 and sample the vertical polarization signal and then the horizontal polarization signal in sequence, and then switch to the next antenna element 37 and repeat the process. In other words, the antenna switching pattern is not limited by the switching network 50.

[0058] Note that Figure 6 The sequence for receiving the CTE 340 and calculating the angle of arrival is shown. The sequence for transmitting the CTE to allow the calculation of the angle of departure is the same. In this embodiment, antenna elements with circular polarization are used during the guard period 341 and the reference period 342. Then the processing unit 20 switches between the antenna elements 37 and / or polarization directions according to a predetermined switching pattern.

[0059] The angle of arrival or angle of departure can be used for many functions. For example, an angle-of-arrival locator can be used to locate a beacon. Such applications can be referred to as wayfinding. For example, the beacon can be a set of car keys or another device that the user needs to find. The user holding the locator device can be guided to the beacon based on the angle of arrival detected by the locator device. For example, a motor vehicle can be equipped with Bluetooth. The owner can send commands to the motor vehicle set in the parking lot to send a beacon or a series of beacons. The locator device carried by the owner detects the angle of arrival and can guide the owner towards the motor vehicle within the parking lot. In another embodiment, a shopping mall can install beacons at certain locations, such as near exits, certain stores, or food courts. Shoppers can use a portable positioning device to utilize these beacons to guide them through the shopping mall. Similarly, the angle of arrival can be used to guide an operator towards an asset in a warehouse or other structure. The locator device can include an indicator that allows the operator to determine the angle of arrival. For example, the locator device can have a visual display indicating the direction of the beacon. Alternatively, the locator device can have an audio output notifying the user of the direction of the beacon.

[0060] When multiple locators are used, the exact position of the transmitter can be determined. Such applications are called spatial positioning. For example, within a structure with multiple positioning devices, the exact position of any transmitter can be determined. This can help replace GPS in these environments because GPS positioning requires more power to execute. In one example, an operator can carry a mobile phone. Multiple locator devices each determine the angle of arrival of the beacon transmitted by the phone. In one embodiment, these angles of arrival are forwarded to the mobile phone. In another embodiment, these angles of arrival are forwarded to a central computing device, which calculates the position of the mobile phone based on all the received angles of arrival. Thus, the mobile phone or other device can use the angles of arrival from each locator device to precisely locate the specific position of the mobile phone. If multiple locator devices are employed, three-dimensional spatial positioning can also be possible.

[0061] A departure angle algorithm can be used to perform similar functions. For example, a user may own a device with a single antenna instead of an antenna array. If the beacons in a shopping mall or warehouse as described above utilize an antenna array, the user's device can determine the departure angle.

[0062] The device is also capable of determining the departure angles from multiple beacons. If the positions of the beacons are known, the device may be able to calculate its spatial position based on these departure angles.

[0063] In other words, this information can be used for wayfinding and spatial positioning in the same manner as the angle-of-arrival information. Additionally, the device can have an indicator that provides an indication of the departure angle to the user. In other embodiments, the device can have an indicator that notifies the user of its spatial position.

[0064] The present system and method have many advantages. First, it has been found that sampling vertical and horizontal polarization signals during AoA calculation improves the accuracy of the calculation, especially in multipath situations.

[0065] In addition, it has been found that using signals with only one polarization (horizontal or vertical) during the reference period may result in weaker signals that produce incorrect gain values.

[0066] The present system and method overcome these drawbacks by providing a switching network that allows the device to sample horizontal and vertical polarization signals separately for each antenna element in the antenna array. In addition, the switching network allows the device to sample circular polarization signals from at least one antenna element in the antenna array. Thus, unlike other embodiments, no additional antenna elements are required to provide circular polarization signals.

[0067] The switching circuit minimizes cost and space while providing this enhanced functionality.

[0068] The scope of the present disclosure is not limited to the specific embodiments described herein. Indeed, various other embodiments and modifications of the present disclosure will be apparent to those of ordinary skill in the art in addition to those described herein. Accordingly, such other embodiments and modifications are intended to fall within the scope of the present disclosure. Moreover, although the present disclosure has been described in the context of specific embodiments implemented for a specific purpose in a specific environment, those of ordinary skill in the art will recognize that the present disclosure is not limited to this and that the present disclosure can be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below should be interpreted in light of the full scope and spirit of the present disclosure as described herein.

Claims

1. A wireless network device, comprising: an antenna array, the antenna array including a plurality of antenna elements, each antenna element including a vertically polarized signal and a horizontally polarized signal; a wireless network interface, wherein the wireless network interface receives an input signal from one of the antenna elements in the antenna array; a processing unit; and a switching network, the switching network being disposed between the antenna array and the wireless network interface to select an antenna element from the antenna array, wherein the switching network includes one or more selection switches, the one or more selection switches serving as a multiplexer and a demultiplexer depending on the direction of activity, the one or more selection switches communicating with the vertically polarized signal and the horizontally polarized signal from each of the plurality of antenna elements, the switching network being configured to couple the horizontally polarized signal or the vertically polarized signal from any one of the plurality of antenna elements to the wireless network interface, and the switching network further being configured to couple at least one circularly polarized signal to the wireless network interface, wherein each circularly polarized signal is formed by combining a vertically polarized signal and a horizontally polarized signal from a single antenna element.

2. The wireless network device according to claim 1, wherein, the wireless network device receives a signal, the signal including a constant tone extension (CTE) having a plurality of switching time slots and sampling time slots.

3. The wireless network device according to claim 2, wherein, the processing unit includes a plurality of output signals communicating with the switching network; wherein the processing unit selects one of the plurality of antenna elements during each switching time slot by modifying the plurality of output signals.

4. The wireless network device according to claim 3, wherein, the CTE further includes a guard period and a reference period, wherein the processing unit modifies the plurality of output signals to receive the circularly polarized signal during at least a portion of the guard period and / or the reference period.

5. The wireless network device according to claim 4, wherein, the wireless network interface includes a programmable gain amplifier (PGA), and the processing unit sets the gain of the PGA based on the amplitude of the circularly polarized signal received during at least a portion of the guard period and / or the reference period.

6. The wireless network device according to claim 4, wherein, the wireless network interface includes a low noise amplifier (LNA), and the processing unit sets the gain of the LNA based on the amplitude of the circularly polarized signal received during the reference period.

7. The wireless network device according to claim 1, wherein, the antenna array includes an N×M array, where N and M are both greater than 1, and the antenna elements disposed along the outer edge of the N×M array are used to provide the circularly polarized signal.

8. The wireless network device according to claim 1, wherein, the antenna array includes an N×M array, where N and M are both greater than 1, and the internal antenna elements are used to provide the circularly polarized signal.

9. A switching network communicating with an antenna array, wherein, Each antenna element in the antenna array includes a horizontally polarized signal and a vertically polarized signal, and the switching network includes: an upper antenna selection switch and a lower antenna selection switch, the upper antenna selection switch and the lower antenna selection switch each having a multiplexed signal and a plurality of demultiplexed signals, wherein the horizontally polarized signal and the vertically polarized signal of each antenna element communicate with a demultiplexed signal on one of the upper antenna selection switch and the lower antenna selection switch; wherein the vertically polarized signal and the horizontally polarized signal of at least one antenna element communicate with demultiplexed signals on different antenna selection switches, and a control signal called ANTENNA SELECT is used to select one of the demultiplexed signals to communicate with the multiplexed signal; an upper polarization switch, the upper polarization switch having a multiplexed signal communicating with the multiplexed signal from the upper antenna selection switch, and the upper polarization switch having a first demultiplexed signal and a second demultiplexed signal, wherein a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal; a lower polarization switch, the lower polarization switch having a multiplexed signal communicating with the multiplexed signal from the lower antenna selection switch, and the lower polarization switch having a first demultiplexed signal and a second demultiplexed signal, wherein a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal; a 90° hybrid, the 90° hybrid communicating with the second demultiplexed signal from the upper polarization switch and the second demultiplexed signal from the lower polarization switch; a bank selection switch, the bank selection switch having a multiplexed signal, a first demultiplexed signal communicating with the first demultiplexed signal from the upper polarization switch, and a second demultiplexed signal communicating with the first demultiplexed signal from the lower polarization switch, wherein a control signal called UPPER / LOWER is used to select one of the demultiplexed signals to communicate with the multiplexed signal; and a main polarization switch, the main polarization switch having a multiplexed signal, a first demultiplexed signal communicating with the multiplexed signal from the bank selection switch, and a second demultiplexed signal communicating with the 90° hybrid, wherein a control signal called CIRCULAR is used to select one of the demultiplexed signals to communicate with the multiplexed signal.

10. The switching network according to claim 9, wherein, the vertically polarized signal and the horizontally polarized signal of at least two antenna elements communicate with demultiplexed signals on different antenna selection switches.

11. The switching network according to claim 9, wherein, the upper antenna selection switch and the lower antenna selection switch each include 16 demultiplexed signals, and the antenna array includes 16 antenna elements.

12. The switching network according to claim 9, further comprising a third antenna selection switch and a fourth antenna selection switch ； wherein the bank selection switch includes: A third demultiplexed signal that communicates with a multiplexed signal from the third antenna selection switch; A fourth demultiplexed signal that communicates with a multiplexed signal from the fourth antenna selection switch; and An additional control signal for selecting among the four demultiplexed signals.

13. The switching network according to claim 9, wherein, the antenna array comprises an N×M array, where both N and M are greater than 1, and one of the at least one antenna element is an internal antenna element.

14. The switching network according to claim 9, wherein, the antenna array comprises an N×M array, where both N and M are greater than 1, and one of the at least one antenna element is disposed along an outer edge of the antenna array.

15. The switching network according to claim 9, wherein, the switching network is adapted to transmit signals to or receive signals from the antenna array.

16. A method for calculating an angle of arrival, comprising: receiving, at a wireless network device, a signal comprising a constant tone extension having a guard period, a reference period, and a plurality of switching time slots and sampling time slots, wherein the wireless network device comprises an antenna array and a switching network, the antenna array comprising a plurality of antenna elements, and the switching network for selecting among signals from the antenna array; configuring the switching network to receive a circularly polarized signal from one of the plurality of antenna elements; receiving the circularly polarized signal during at least a portion of the guard period and / or the reference period; configuring the switching network to receive a horizontally polarized signal from a first one of the plurality of antenna elements during a switching time slot; receiving the horizontally polarized signal from the first one of the plurality of antenna elements during a sampling time slot; configuring the switching network to receive a vertically polarized signal from the first one of the plurality of antenna elements during a switching time slot; receiving the vertically polarized signal from the first one of the plurality of antenna elements during a sampling time slot; repeating the configuring and receiving to receive vertically polarized signals and horizontally polarized signals from all antenna elements in the antenna array; using information from the horizontally polarized signals and the vertically polarized signals to calculate the angle of arrival.

17. The method according to claim 16, further comprising using information from the circularly polarized signal to set a gain of a programmable gain amplifier (PGA).

18. The method according to claim 16, further comprising using information from the circularly polarized signal to set a gain of a low noise amplifier (LNA).

19. The method according to claim 16, wherein, the antenna array comprises an N×M array, where both N and M are greater than 1, and the circularly polarized signal is received from an internal antenna element.

20. The method according to claim 16, wherein, the antenna array comprises an N×M array, where both N and M are greater than 1, and the circularly polarized signal is received from an antenna element disposed along an outer edge of the antenna array.

Images