A method, apparatus and storage medium for solving multipath effect

Abstract

The embodiment of the present application discloses a method, device and storage medium for solving multipath effect, wherein the method for solving multipath effect comprises: firstly, establishing one-to-one mapping relationship between each virtual antenna and each physical antenna, and setting antenna address and antenna frequency of each physical antenna based on the mapping relationship; then, each virtual antenna respectively performs time-sharing communication with a plurality of terminals through the mapped physical antenna; finally, periodically adjusting the one-to-one mapping relationship between each virtual antenna and each physical antenna based on preset adjustment rule. By using the present application, the problem of multipath effect is solved based on software algorithm, and the present application has the advantages of simple structure and low cost.

Description

Technical Field

[0001] This invention relates to the field of wireless communication technology, and in particular to a method, apparatus, and storage medium for solving multipath effects. Background Technology

[0002] Multipath effect refers to the phenomenon where electromagnetic waves propagate along different paths, causing different component fields to arrive at the receiver at different times. These components then superimpose their phases, causing interference and resulting in signal distortion or errors. For example, if an electromagnetic wave propagates along two different paths with a length difference of exactly half a wavelength, the two signals will cancel each other out upon reaching their destinations.

[0003] Multipath effects can be addressed by improving the distance measurement accuracy of the receiver, using anti-multipath antennas, and employing anti-multipath signal processing and adaptive cancellation techniques. However, these solutions suffer from significant drawbacks such as equipment complexity and high cost in low-cost indoor applications. Summary of the Invention

[0004] The present invention aims to provide a method, device, and storage medium for solving the multipath effect, so as to solve the problem that the existing multipath effect solutions are not suitable for indoor multi-terminal wireless communication scenarios.

[0005] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:

[0006] According to one aspect of the present invention, a method for solving multipath effects is provided, the method being applied to a base station, the base station being provided with a plurality of virtual antennas and a plurality of physical antennas, wherein the number of virtual antennas is not less than the number of physical antennas, the method comprising:

[0007] Establish a one-to-one mapping relationship between each virtual antenna and each physical antenna;

[0008] Based on the mapping relationship, the antenna address and antenna frequency of each physical antenna are set;

[0009] Each of the virtual antennas communicates with several bound terminals in a time-division manner through a mapped physical antenna;

[0010] The one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted based on a preset adjustment rule. Based on the adjusted mapping relationship, the antenna address and antenna frequency of each physical antenna are reset so that any virtual antenna is mapped to a different physical antenna in adjacent periods.

[0011] Optionally, the virtual antenna corresponds to a unique virtual antenna address and a different virtual antenna frequency. Based on the mapping relationship, the step of setting the antenna address and antenna frequency of each physical antenna includes:

[0012] Based on each physical antenna, the antenna address and antenna frequency of the physical antenna are set to the virtual antenna address and virtual antenna frequency of the mapped virtual antenna.

[0013] Optionally, the plurality of physical antennas consists of an equal number of left-polarized antennas and right-polarized antennas, and the left-polarized antennas and the right-polarized antennas are arranged alternately.

[0014] Optionally, before the step of each of the virtual antennas communicating with the bound terminals via a mapped physical antenna in a time-division manner, the method further includes:

[0015] The transmit power of each physical antenna is dynamically set.

[0016] Optionally, the step of dynamically setting the transmission power of each of the physical antennas includes:

[0017] The first period is defined as the time slot in which each virtual antenna communicates with each bound terminal in a time-division manner. Based on the first period, the transmission power of the physical antenna mapped by the virtual antenna is periodically set, and the transmission power is obtained through a random function.

[0018] Optionally, the method further includes:

[0019] The maximum cumulative duration of each virtual antenna and each bound terminal completing one communication is taken as the second period. Based on the second period and the preset adjustment rules, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted.

[0020] Optionally, the step of establishing a one-to-one mapping relationship between each of the virtual antennas and each of the physical antennas includes:

[0021] Arrange the physical antennas into a queue;

[0022] Establish a one-to-one mapping relationship between each virtual antenna and a position number in the queue;

[0023] The step of periodically adjusting the one-to-one mapping relationship between each virtual antenna and each physical antenna based on the second period and a preset adjustment rule includes:

[0024] Based on each virtual antenna, obtain the first position number mapped by the virtual antenna in the previous second cycle;

[0025] The second position number mapped by the virtual antenna in the current second cycle is determined based on the first position number and the adjustment rule;

[0026] Establish a mapping relationship between the virtual antenna and the second position number.

[0027] Optionally, the step of determining the second position number mapped by the virtual antenna in the current second cycle based on the first position number and the adjustment rule includes:

[0028] Based on the first position number, the second position number is obtained by cyclically moving the queue a preset number of positions in a preset direction.

[0029] According to another aspect of the present invention, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and running thereon, wherein the processor executes the program to implement the steps of the method for solving the multipath effect described in any of the preceding claims.

[0030] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method for resolving multipath effects as described in any of the preceding claims.

[0031] The beneficial effects of this invention are as follows: Unlike existing technologies, this invention first establishes a one-to-one mapping relationship between each virtual antenna and each physical antenna, and based on this mapping relationship, sets the antenna address and antenna frequency of each physical antenna; then, each virtual antenna communicates with several bound terminals through its mapped physical antenna in a time-division manner; finally, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted based on a preset adjustment rule. Using this invention, when a terminal communicates wirelessly with a base station, each received or transmitted data is transmitted through a different wireless path, thus solving the multipath effect problem. The solution of this invention is entirely based on software algorithms, which, compared to existing technologies that solve the multipath effect problem through hardware devices, has the advantages of simple structure and low cost. Attached Figure Description

[0032] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0033] Figure 1 This is a schematic diagram of an indoor multi-terminal wireless communication system provided in an embodiment of the present invention;

[0034] Figure 2 This is a flowchart illustrating a method for solving the multipath effect provided in Embodiment 1 of the present invention;

[0035] Figure 3 This is a schematic diagram of adjusting the mapping relationship provided in Embodiment 1 of the present invention;

[0036] Figure 4 This is a schematic diagram of the structure of an electronic device provided in Embodiment 2 of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0040] This invention provides a solution to the multipath effect problem, adaptable to multi-terminal wireless communication scenarios, particularly indoor multi-terminal wireless communication scenarios. Figure 1 The diagram illustrates an indoor multi-terminal wireless communication system according to an embodiment of the present invention. The system includes a base station and several terminals. Specifically, this system is applied in a classroom teaching scenario, with each terminal corresponding to a question-answering device. To handle data communication from hundreds of question-answering devices, multiple physical antennas are installed within the base station, each communicating with a corresponding subset of terminals. Due to the limited indoor space, when each question-answering device sends or receives electromagnetic signals, some of the signals are reflected through the walls, creating multiple transmission paths and resulting in a multipath effect.

[0041] Example 1

[0042] According to embodiments of the present invention, a method for solving multipath effects is provided. Please refer to... Figures 2 to 3 This is a schematic diagram illustrating a method for solving multipath effects provided in Embodiment 1 of the present invention. This embodiment of the invention is adaptable to scenarios where multiple terminals communicate wirelessly with a base station. The method is executed by the base station, which is equipped with multiple virtual antennas and multiple physical antennas, wherein the number of virtual antennas is not less than the number of physical antennas. The method specifically includes the following steps:

[0043] Step 201: Establish a one-to-one mapping relationship between each virtual antenna and each physical antenna.

[0044] In one embodiment of the present invention, the base station virtualizes the same number of virtual antennas or fewer virtual antennas than the number of physical antennas, and sets the parameter information of each virtual antenna. The frame format for setting the parameter information of the virtual antennas is shown in the table below:

[0045] Table 1

[0046]

[0047] Each virtual antenna has a unique virtual antenna address and a different virtual antenna frequency. After setting up the virtual antennas, a one-to-one mapping relationship is established between each virtual antenna and each physical antenna. One implementation is to sort the physical antennas into a queue; and establish a one-to-one mapping relationship between each virtual antenna and a position number in the queue. The one-to-one mapping relationship means that each virtual antenna maps to one physical antenna, and each physical antenna maps to zero or one virtual antenna. It is understood that when establishing the one-to-one mapping relationship, the virtual antennas can also be sorted into another queue, and then the one-to-one mapping relationship between each virtual antenna and each physical antenna can be established based on the same position number. Another implementation is to establish a one-to-one mapping relationship between each virtual antenna and each physical antenna based on the user's pre-set configuration information. The configuration information may include the parameter information of each virtual antenna and the mapping information between each virtual antenna and each physical antenna. It is understood that the user can also establish a one-to-one mapping relationship between each virtual antenna and each physical antenna based on other implementation methods. When the number of physical antennas is greater than the number of virtual antennas, the number of physical antennas equal to the number of virtual antennas is selected first, and then the one-to-one mapping relationship between each virtual antenna and each physical antenna is established.

[0048] Specifically, suppose a base station device includes four physical antennas ABCD. The software generates four virtual antennas abcd. Virtual antenna a has the following virtual antenna addresses: 0xEF 0xAF 0x01 0x10 0x21 and a frequency of 2.411 GHz; virtual antenna b has the following virtual antenna addresses: 0xEF 0xBF 0x02 0x21 0x22 and a frequency of 2.421 GHz; virtual antenna c has the following virtual antenna addresses: 0xEF 0xCF 0x03 0x31 0x23 and a frequency of 2.431 GHz; and virtual antenna d has the following virtual antenna addresses: 0xEF 0xDF 0x04 0x41 0x24 and a frequency of 2.441 GHz. Initially, the virtual antennas abcd are mapped to the physical antennas ABCD respectively.

[0049] To reduce signal interference within the base station, the base station includes an equal number of left-polarized antennas and right-polarized antennas, arranged alternately. In one embodiment, when the number of physical antennas is even, the number of left-polarized antennas is the same as the number of right-polarized antennas; when the number of physical antennas is odd, the number of left-polarized antennas differs from the number of right-polarized antennas by one. Figure 3 As shown, the four antennas ABCD are arranged in a grid pattern, with each pair separated by 0.5 wavelengths. Antenna AC is a left-polarized antenna, and antenna BD is a right-polarized antenna.

[0050] Step 202: Based on the mapping relationship, set the antenna address and antenna frequency of each physical antenna.

[0051] For each physical antenna, set its antenna address and frequency to the virtual antenna address and frequency of the mapped virtual antenna. If a physical antenna does not have a mapped virtual antenna, no settings are required.

[0052] The transmit power of a physical antenna can affect the location where multipath effects occur. To prevent multipath effects from always occurring at the same location, which would cause terminals located at that location to be in a state of communication abnormality for a long time, the transmit power of the physical antenna is dynamically set, as detailed below.

[0053] Step 203: Each of the virtual antennas communicates with several bound terminals through the mapped physical antennas in a time-division manner.

[0054] Assumption Figure 3 The base station is used for wireless communication with 120 terminals. Each virtual antenna is pre-bound to a corresponding terminal. For example, virtual antenna a is bound to terminals numbered 1-30, virtual antenna b to terminals numbered 61-60, virtual antenna c to terminals numbered 61-90, and virtual antenna a to terminals numbered 91-120. After binding, each virtual antenna communicates with its bound terminal in a time-division multiplexing manner. Generally, each virtual antenna communicates with its bound terminal in the same time slot.

[0055] To avoid multipath effects always occurring at the same location, the transmit power of each physical antenna is dynamically set before each virtual antenna communicates with the bound terminals via its mapped physical antenna. This dynamic setting includes periodic dynamic setting and irregular dynamic setting. Preferably, periodic dynamic setting is used. In one embodiment, the time slot for each virtual antenna to communicate with the bound terminals is taken as the first period. Based on this first period, the transmit power of the physical antenna mapped by the virtual antenna is periodically set, where the transmit power is obtained through a random function. For example, if virtual antenna a maps to physical antenna A, and communicates with 30 bound terminals via time slot t, the base station generates a random number every time slot t based on the random function and sets the transmit power of physical antenna A to this random number, so that physical antenna A uses a different transmit power to communicate with each terminal each time. It is understood that the first period is not limited to the time slot for each virtual antenna to communicate with the bound terminals via time-division multiplexing; it can also be twice the time slot or other durations. Because each virtual antenna uses a different antenna frequency, all virtual antennas operate simultaneously when the base station communicates with each terminal.

[0056] In one embodiment of the present invention, a frame format for wireless communication between a virtual antenna and a bound terminal, as shown in the table below, is provided.

[0057] Table 2

[0058]

[0059] Step 204: Based on preset adjustment rules, periodically adjust the one-to-one mapping relationship between each virtual antenna and each physical antenna, and based on the adjusted mapping relationship, reset the antenna address and antenna frequency of each physical antenna so that any virtual antenna is mapped to a different physical antenna in adjacent periods.

[0060] In one embodiment, the second period is defined as the maximum cumulative duration of each virtual antenna completing one communication session with each bound terminal. Based on this second period and a preset adjustment rule, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted. When each virtual antenna uses the same time slot to perform time-division multiplexing communication with the same number of terminals, the second period = time slot * number of terminals bound to each virtual antenna. For example, if each virtual antenna uses the same time slot t to perform time-division multiplexing communication with 30 terminals, the period for adjusting the mapping relationship is 30t. When each virtual antenna uses the same or different time slots to perform time-division multiplexing communication with different numbers of terminals, the second period is the maximum cumulative duration of each virtual antenna completing one communication session with each bound terminal. For example, if virtual antenna a is bound to 20 terminals and virtual antenna b is bound to 21 terminals, and the communication time slot for both virtual antenna a and virtual antenna b is t, then the second period is 21t.

[0061] To facilitate adjusting the mapping relationship between virtual and physical antennas, the physical antennas are sorted into a queue; a one-to-one mapping relationship is established between each virtual antenna and a position number in the queue. In one embodiment of the present invention, the method for adjusting this mapping relationship includes: based on each virtual antenna, first obtaining the first position number mapped to the virtual antenna in the previous second cycle; determining the second position number mapped to the virtual antenna in the current second cycle according to the first position number and adjustment rules; and establishing a mapping relationship between the virtual antenna and the second position number. Specifically, determining the second position number mapped to the virtual antenna in the current second cycle according to the first position number and adjustment rules involves: based on the first position number, cyclically moving the virtual antenna a preset number of positions in a preset direction within the queue to obtain the second position number. The preset direction includes a direction towards the tail of the queue and a direction towards the head of the queue. Figure 3 As shown, physical antennas ABCD are arranged in a queue, with A at the head and D at the tail. Before adjustment, the one-to-one mapping relationship between virtual antennas abcd and physical antennas ABCD is aA, bB, cC, dD. The preset adjustment rule is to cyclically move one position towards the tail of the queue. After adjustment, the one-to-one mapping relationship between each virtual antenna and each physical antenna is aB, bC, cD, dA.

[0062] Wireless communication between the virtual antenna and the terminal is actually accomplished through the physical antenna. Changing the mapping relationship between the virtual antenna and the physical antenna alters the wireless transmission path when the terminal communicates with the base station. For example, in the previous second cycle, virtual antenna 'a' communicated with terminal number 1 via physical antenna A in a time-division manner, with the wireless transmission path running from the location of terminal number 1 to the location of physical antenna A. In the current second cycle, virtual antenna 'a' communicates with terminal number 1 via physical antenna B in a time-division manner, with the wireless transmission path running from the location of terminal number 1 to the location of physical antenna B. Because the wireless transmission paths are different in the two communications, the multipath effect problem is avoided.

[0063] The method for solving multipath effects provided in this invention first establishes a one-to-one mapping relationship between each virtual antenna and each physical antenna, and sets the antenna address and antenna frequency of each physical antenna based on the mapping relationship; then, each virtual antenna communicates with several bound terminals through the mapped physical antenna in a time-division multiplexing manner; finally, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted based on a preset adjustment rule. Using this invention, when a terminal communicates wirelessly with a base station, each received or transmitted data is transmitted through a different wireless path, thereby solving the multipath effect problem. The solution of this invention is entirely based on software algorithms, which, compared to existing technologies that solve multipath effects through hardware devices, has the advantages of simple structure and low cost.

[0064] Example 2

[0065] According to embodiments of the present invention, a three-dimensional measuring device is provided, such as... Figure 4 The diagram shown is a structural schematic of an electronic device according to Embodiment 2 of the present invention. The electronic device may include a processor 401, a communication interface 402, a memory 403, and a communication bus 404. The processor 401, communication interface 402, and memory 403 communicate with each other via the communication bus 404. The processor 401 can call logical instructions in the memory 403 to execute the method for solving multipath effects in Embodiment 1. The method for solving multipath effects includes: establishing a one-to-one mapping relationship between each virtual antenna and each physical antenna; setting the antenna address and antenna frequency of each physical antenna based on the mapping relationship; each virtual antenna communicating with several bound terminals in a time-division manner through its mapped physical antenna; periodically adjusting the one-to-one mapping relationship between each virtual antenna and each physical antenna based on a preset adjustment rule; and resetting the antenna address and antenna frequency of each physical antenna based on the adjusted mapping relationship, so that any virtual antenna maps to different physical antennas in adjacent periods.

[0066] Furthermore, the logical instructions in the aforementioned memory 403 can be implemented as software functional units and, when sold or used as independent products, can be stored in several computer-readable storage media. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of any of the methods described in Embodiment 1 of the present invention. The aforementioned storage media include: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and various other media capable of storing program code.

[0067] The above-mentioned product can perform any of the methods for solving multipath effects described in Embodiment 1, and has the corresponding functional modules and beneficial effects of the method. For technical details not described in detail in this embodiment, please refer to the method for solving multipath effects provided in Embodiment 1 of the present invention.

[0068] Example 3

[0069] According to an embodiment of the present invention, a computer-readable storage medium of the type described in Embodiment 2 is provided. The computer-readable storage medium stores a computer program. When the computer program is executed by a processor, the processor performs the steps of the method for solving the multipath effect described in any of Embodiment 1.

[0070] The above-mentioned product can perform any of the methods for solving multipath effects described in Embodiment 1, and has the corresponding functional modules and beneficial effects of the method. For technical details not described in detail in this embodiment, please refer to the method for solving multipath effects provided in Embodiment 1 of the present invention.

[0071] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented using software plus a general-purpose hardware platform, or of course, using hardware. Based on this understanding, the above technical solutions, in essence or the parts that contribute to the related technology, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to enable a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; under the concept of the present invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the present invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for solving multipath effect, the method being applied to a base station, characterized in that, The base station is equipped with multiple virtual antennas and multiple physical antennas, and the number of virtual antennas is not less than the number of physical antennas. The method includes: Establish a one-to-one mapping relationship between each virtual antenna and each physical antenna; Based on the mapping relationship, the antenna address and antenna frequency of each physical antenna are set; Each of the virtual antennas communicates with several bound terminals in a time-division manner through a mapped physical antenna; Based on preset adjustment rules, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted, and based on the adjusted mapping relationship, the antenna address and antenna frequency of each physical antenna are reset so that any virtual antenna is mapped to a different physical antenna in adjacent periods. The setting of the antenna address and antenna frequency of each of the physical antennas includes: Set the antenna address and antenna frequency of the physical antenna to the virtual antenna address and virtual antenna frequency of the mapped virtual antenna.

2. The method according to claim 1, characterized in that, The virtual antenna corresponds to a unique virtual antenna address and a different virtual antenna frequency. Based on the mapping relationship, the step of setting the antenna address and antenna frequency of each physical antenna includes: Based on each physical antenna, the antenna address and antenna frequency of the physical antenna are set to the virtual antenna address and virtual antenna frequency of the mapped virtual antenna.

3. The method according to claim 1, characterized in that, The plurality of physical antennas consist of an equal number of left-polarized antennas and right-polarized antennas, and the left-polarized antennas and the right-polarized antennas are arranged alternately.

4. The method according to claim 1, characterized in that, Before the step of each of the virtual antennas communicating in time-division multiplexing with the bound terminals through the mapped physical antenna, the method further includes: The transmit power of each physical antenna is dynamically set.

5. The method according to claim 4, characterized in that, The step of dynamically setting the transmission power of each physical antenna includes: The first period is defined as the time slot in which each virtual antenna communicates with each bound terminal in a time-division manner. Based on the first period, the transmission power of the physical antenna mapped by the virtual antenna is periodically set, and the transmission power is obtained through a random function.

6. The method according to any one of claims 1 to 5, characterized in that, The method further includes: The maximum cumulative duration of each virtual antenna and each bound terminal completing one communication is taken as the second period. Based on the second period and the preset adjustment rules, the one-to-one mapping relationship between each virtual antenna and each physical antenna is periodically adjusted.

7. The method according to claim 6, characterized in that, The step of establishing a one-to-one mapping relationship between each virtual antenna and each physical antenna includes: Arrange the physical antennas into a queue; Establish a one-to-one mapping relationship between each virtual antenna and a position number in the queue; The step of periodically adjusting the one-to-one mapping relationship between each virtual antenna and each physical antenna based on the second period and a preset adjustment rule includes: Based on each virtual antenna, obtain the first position number mapped by the virtual antenna in the previous second cycle; The second position number mapped by the virtual antenna in the current second cycle is determined based on the first position number and the adjustment rule; Establish a mapping relationship between the virtual antenna and the second position number.

8. The method according to claim 7, characterized in that, The step of determining the second position number mapped by the virtual antenna in the current second cycle based on the first position number and the adjustment rule includes: Based on the first position number, the second position number is obtained by cyclically moving the queue a preset number of positions in a preset direction.

9. An electronic device, comprising a memory, a processor, and a computer program stored in the memory and running thereon, characterized in that, When the processor executes the program, it implements the steps of the method for solving multipath effects as described in any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the method for resolving multipath effects as described in any one of claims 1-8.

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