Pilot allocation method for joint communication and positioning (JCAP) in millimeter-wave band

Abstract

The present invention relates to the technical field of wireless communication and positioning based on a millimeter wave, and relates to a pilot frequency distribution method for joint communication

Description

A pilot allocation method for joint communication and positioning in millimeter wave frequency band

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 26, 2022, with application number 202211670525.7 and invention name “A pilot allocation method for joint communication and positioning in millimeter wave frequency band”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of millimeter wave wireless communication and positioning technology, and more specifically, to a pilot allocation method for millimeter wave frequency band joint communication and positioning. Background Art

[0003] In wireless communication systems, in order to increase data transmission rate and reduce data transmission delay, it is very useful to obtain the precise location information of mobile terminals. Accurate positioning can also improve channel estimation accuracy, thereby improving the performance of wireless communication systems.

[0004] Applications that require positioning (such as autonomous driving systems) require both communication and positioning hardware. During communication, users need to estimate instantaneous channel state information, a step achieved by inserting pilot signals into the transmitted signal. Pilot signals are signals agreed upon by the transmitter and receiver and therefore do not transmit data. When a base station or user receives the pilot signal, it can estimate the channel state information based on the pilot signal's fading. Generally speaking, the more pilot signals inserted, the higher the channel estimation accuracy. However, inserting too many pilot signals increases the space available for data transmission, reducing data transmission efficiency.

[0005] In communication systems that use channel estimation for positioning, pilots must be inserted into both uplink and downlink signals. The proportion of pilots in the signal significantly impacts both communication and positioning performance. Traditional signal structures designed solely for communication fail to consider positioning requirements and minimize the pilot ratio.

[0006] Summary of the Invention

[0007] The present invention proposes a joint communication and positioning pilot allocation method based on the millimeter wave frequency band, which can dynamically adjust the pilot ratio while considering both communication and positioning requirements to obtain a more accurate target position estimation.

[0008] In a first aspect, a pilot allocation method for joint communication and positioning in a millimeter wave frequency band is provided, comprising:

[0009] Step 1: The user establishes communication with the base station, and the base station receives the uplink signal sent by the user;

[0010] Step 2: The base station obtains uplink channel state information based on the uplink signal, calculates the time delay, transmission angle, and arrival angle of the uplink signal using a parameter estimation algorithm, and calculates the coordinates of the user based on the spatial position coordinates of the base station at this time;

[0011] Step 3: Based on the user's communication needs, the base station uses an alternating optimization algorithm to calculate an uplink and downlink pilot allocation scheme that meets the user's communication needs and maximizes positioning accuracy.

[0012] Step 4: The base station sends the pilot allocation plan along with the user data to the user in the downlink. At the same time, the base station adjusts its own working mode according to the pilot allocation plan and prepares to receive the signal of the next cycle.

[0013] Step 5: The user receives the downlink signal from the base station, obtains the downlink channel state information, and uses a parameter estimation algorithm to calculate the downlink signal's delay, transmission angle, and arrival angle. The user's coordinates are then calculated based on the spatial coordinates received from the base station. The final position estimate is then obtained by weighting the uplink and downlink channel estimation results.

[0014] Step 6: The user adjusts its own working mode according to the position estimation and pilot allocation, starts the next cycle of data transmission, and returns to step 2.

[0015] Preferably, in step 1, the uplink signal sent by the user reaches the base station through multiple paths, and the signal received by the base station is expressed as:

[0016] Among them, θ i is the transmission angle of the uplink signal, β i is the path gain, a Rx (θ i ), is the steering vector, where the superscript H represents the conjugate vector, φ i represents the angle of arrival, F is the uplink beamforming matrix, N is Gaussian noise, Y is the received signal, S is the transmitted signal, τ i is the path delay of the uplink signal.

[0017] Preferably, the path includes a line-of-sight path and a non-line-of-sight path.

[0018] Preferably, in step 2, the parameter estimation algorithm includes a multi-signal classification algorithm (Multi-Signal Classification, MUSIC) and a signal parameter estimation algorithm based on rotation invariance technology.

[0019] Preferably, in step 3, the base station optimizes the pilot ratio according to channel state information, line-of-sight path parameters, communication performance requirements and positioning performance requirements.

[0020] Preferably, in step 5, the weighting of the uplink channel and downlink channel estimation results to obtain the final position estimate includes: taking an average of the uplink estimated position and the downlink estimated position, or taking a weighted average according to the signal-to-noise ratio of the uplink signal and the downlink signal.

[0021] Preferably, in step 5, the acquiring of the downlink channel state information includes: performing channel estimation on the downlink signal to acquire the downlink channel state information, or using the uplink channel state information in step 2 as the downlink channel state information.

[0022] In the second aspect, a pilot allocation system for joint communication and positioning in the millimeter wave frequency band is provided, which is used to execute the pilot allocation method for joint communication and positioning in the millimeter wave frequency band described in the first aspect, including a base station and at least one user, and the base station and the user are communicated with each other.

[0023] In a third aspect, a computer storage medium is provided, in which a computer program is stored; when the computer program runs on a computer, the computer executes the pilot allocation method for millimeter wave frequency band joint communication and positioning described in the first aspect.

[0024] The beneficial effects of the present invention are: the present invention can simultaneously realize the two functions of positioning and communication in the same frequency band, and through continuous iterative optimization of the working mode, improve the real-time positioning accuracy and communication rate to meet system requirements; and the real-time iterative working mode of the present invention can realize continuous high-precision tracking of user positions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] FIG1 is a schematic diagram of a system architecture of an application scenario to which the present invention is applicable;

[0027] FIG2 is a flowchart of the user and base station system used in the present invention;

[0028] FIG3 is a simulation comparison diagram of the present invention and the simulation comparison diagram of the present invention;

[0029] FIG4 is a diagram showing the allocation of pilot resources for uplink and downlink joint positioning in the simulation of the present invention. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] Example 1:

[0032] A pilot allocation system for millimeter-wave frequency band joint communication and positioning, as shown in Figure 1, includes a base station s and at least one user (e.g., user i and user j), with a communication connection between the base station and the user. Signals sent by the base station to the user can reach the user via different paths, such as the direct path and indirect path shown in Figure 1.

[0033] For example, the base station is equipped with 64 antennas and the user is equipped with 16 antennas. The time division duplex period is 10us, which contains 28 symbols, including pilot symbols and data symbols. In addition, this embodiment assumes that the user transmits signal antenna power of 15dBm, the base station transmits power of 65dBm, and the environmental background noise is -170dBm. The base station is the origin, the horizontal axis is the x-axis, and the vertical axis is the y-axis. The user's initial position is 500m away from the base station, and the specific coordinates are (-400, 300). Under the Robustness test of the mobile scenario, the user will move in the positive direction of the x-axis at different initial speeds. In addition, this embodiment assumes that the user is at the initial position and does not change. When the user sends uplink data to the base station, it will also send its own communication rate requirements to the user.

[0034] Example 2:

[0035] Since the channel state information contains some information about the physical space (such as the angle of the receiving end relative to the transmitting end), the channel state information can be used to locate the user, that is, communication and positioning integration.

[0036] This paper proposes a pilot allocation method for combined communication and positioning in the millimeter wave frequency band. This method transmits a pilot to extract the user's location from the channel and, based on the positioning results, reversely updates the pilot allocation in the user's transmitted signal, maximizing positioning accuracy while meeting communication requirements. Furthermore, this method integrates positioning into the communication process, requiring only one set of antenna equipment, thereby reducing hardware costs and power consumption.

[0037] Specifically, a pilot allocation method for joint communication and positioning in the millimeter wave frequency band, as shown in FIG2 , includes:

[0038] Step 1: The user establishes communication with the base station, and the base station receives the uplink signal sent by the user.

[0039] In step 1, the uplink signal sent by the user reaches the base station through multiple paths. The signal received by the base station is expressed as:

[0040] Where i = 0, 1, ..., p, p is the number of users, t is the time when the base station receives the signal, θ i is the transmission angle of the uplink signal, β i is the path gain, a Rx (θ i ), is the steering vector, expressed as:

[0041] Among them, Δ Rx is the receiving antenna spacing after normalization of the signal wavelength.

[0042] Δ Tx is the transmit antenna spacing after normalization of the signal wavelength. In addition, F is the uplink beamforming matrix, N is Gaussian noise, Y is the received signal, S is the transmitted signal, and τ i is the path delay of the uplink signal.

[0043] In step 1, the signal strength attenuation of each path is derived from the formula, which is expressed as follows when the subscript i of different paths is omitted: β = α + 10γlog 10 (d)+ξ[dB]

[0044] Where ξ is the variance σ 2 , a Gaussian random variable with a mean of 0; α and γ are path parameters. The path includes a line-of-sight path and a non-line-of-sight path. For the line-of-sight path, this embodiment takes α = 61.4, γ = 2, and σ = 5.8; for the non-line-of-sight path, this embodiment takes α = 72.0, γ = 2.92, and σ = 8.7. In an actual scenario, there may be a large number of non-line-of-sight paths. In order to simplify the model, this embodiment only selects the non-line-of-sight path generated by a single reflection. Usually, multiple reflections will cause the signal of the path to decay rapidly, and the signal obtained by the receiver from the line-of-sight path and the single-reflection non-line-of-sight path contains more than 90% of all signal powers that the receiver can receive.

[0045] Step 2: The base station obtains uplink channel state information based on the uplink signal and uses a parameter estimation algorithm to calculate the uplink signal's time delay τ1, transmission angle φ1, and arrival angle θ1. The base station then calculates the user's coordinates based on the base station's spatial position at that time. The base station stores its own spatial position information locally. Assuming the coordinates of this position are (X, Y), and assuming the base station's receiving antenna is oriented in the positive Y direction, the user's coordinates can be calculated as (X + c0τ1sinθ1, Y + c0τ1cosθ1).

[0046] In step 2, the parameter estimation algorithm includes a multi-signal classification algorithm and a signal parameter estimation algorithm based on rotation invariance technology.

[0047] Step 3: Based on the user's communication needs, the base station uses an alternating optimization algorithm to calculate an uplink and downlink pilot allocation scheme that meets the user's communication needs and maximizes positioning accuracy.

[0048] In step 3, the base station optimizes the pilot ratio based on channel state information, line-of-sight path parameters, communication performance requirements, and positioning performance requirements.

[0049] For example, after receiving the user's uplink signal through steps 2 and 3, the base station estimates the uplink channel state information matrix H and uses a multi-signal classification algorithm to calculate the path with the highest power, namely the receiving angle, transmitting angle, and delay of the line-of-sight path, and converts this into the corresponding relative position of the user. Furthermore, the base station uses a particle swarm algorithm to optimize the optimal uplink and downlink pilot ratios in this scenario.

[0050] Step 4: The base station sends the pilot allocation plan together with the user data to the user in the downlink. At the same time, the base station adjusts its own working mode according to the pilot allocation plan and prepares to receive the signal of the next cycle.

[0051] Step 5: The user receives the downlink signal from the base station, obtains the downlink channel state information, and uses the parameter estimation algorithm to calculate the downlink signal delay τ2, transmission angle φ2 and arrival angle θ2, and calculates the user's coordinates based on the spatial position coordinates (X, Y) received from the base station. The final position estimate is then obtained by weighting the results of the uplink channel and downlink channel estimation.

[0052] In step 5, the final position estimate is obtained by weighting the results of the uplink channel and downlink channel estimation, including: taking the average of the uplink estimated position and the downlink estimated position, or obtaining the credibility of the uplink signal and the downlink signal based on the signal-to-noise ratio, and obtaining the uplink and downlink integrated user position estimate based on this weighting.

[0053] Given the reciprocity between the uplink and downlink, the channel information estimated using the uplink can be directly used for the downlink. In this case, the combined uplink and downlink algorithm can be degenerated into an uplink-only or downlink-only positioning algorithm. Therefore, there are various ways to obtain downlink channel state information, including: the user end repeats the position estimation portion in step 2 to calculate a position estimate based on the downlink channel state information, i.e., performing channel estimation on the downlink signal to obtain downlink channel state information, or using the uplink channel state information in step 2 as the downlink channel state information.

[0054] Step 6: The user adjusts its own working mode according to the position estimation and pilot allocation, starts the next cycle of data transmission, and returns to step 2.

[0055] The positioning accuracy of the present invention under different communication rate requirements is shown in Figure 3. Compared with the performance of the beamforming algorithm of the fixed pilot, it can be seen that the dynamic pilot can significantly improve the positioning performance under low communication requirements. Figure 4 shows the pilot resource allocation of the uplink and downlink joint positioning.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A pilot allocation method for joint communication and positioning in millimeter wave frequency band, It is characterized in that include: Step 1: The user establishes communication with the base station, and the base station receives the uplink signal sent by the user; Step 2: The base station obtains uplink channel state information according to the uplink signal, calculates the delay, transmission angle and arrival angle of the uplink signal by using a parameter estimation algorithm, and calculates the coordinates of the user according to the spatial position coordinates of the base station at this time; Step 3: The base station uses an alternating optimization algorithm to calculate an uplink and downlink pilot allocation scheme that meets the user's communication needs and maximizes positioning accuracy according to the user's communication needs. Step 4: The base station sends the pilot allocation plan together with the user data to the user in the downlink. At the same time, the base station adjusts its own working mode according to the pilot allocation plan and prepares to receive the signal of the next cycle. Step 5: The user receives the downlink signal from the base station, obtains the downlink channel state information, calculates the delay, transmission angle and arrival angle of the downlink signal using the parameter estimation algorithm, and calculates the coordinates of the user based on the spatial position coordinates received from the base station; then, the final position estimate is obtained by weighting the results of the uplink channel and downlink channel estimation; Step 6: The user adjusts its own working mode according to the position estimation and pilot allocation, starts the next cycle of data transmission, and returns to step 2.

2. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 1, It is characterized in that In step 1, the uplink signal sent by the user reaches the base station through multiple paths, and the signal received by the base station is expressed as: Among them, θ i is the transmission angle of the uplink signal, β i is the path gain, a Rx (θ i ), is the steering vector, where the superscript H represents the conjugate vector, φ i represents the angle of arrival, F is the uplink beamforming matrix, N is Gaussian noise, Y is the received signal, S is the transmitted signal, τ i is the path delay of the uplink signal.

3. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 2, It is characterized in that The paths include line-of-sight paths and non-line-of-sight paths.

4. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 3, It is characterized in that In step 2, the parameter estimation algorithm includes a multi-signal classification algorithm and a signal parameter estimation algorithm based on rotation invariance technology.

5. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 4, It is characterized in that In step 3, the base station optimizes the pilot ratio according to channel state information, line-of-sight path parameters, communication performance requirements, and positioning performance requirements.

6. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 5, It is characterized in that In step 5, the final position estimation is obtained by weighting the results of uplink channel and downlink channel estimation, including: taking an average of the uplink estimated position and the downlink estimated position, or taking a weighted average according to the signal-to-noise ratio of the uplink signal and the downlink signal.

7. The pilot allocation method for millimeter wave frequency band joint communication and positioning according to claim 6, It is characterized in that In step 5, the acquiring of downlink channel state information includes: performing channel estimation on the downlink signal to acquire the downlink channel state information, or using the uplink channel state information in step 2 as the downlink channel state information.

8. A pilot allocation system for joint communication and positioning in the millimeter wave frequency band, It is characterized in that The pilot allocation method for executing the millimeter wave frequency band joint communication and positioning as described in claim 1 includes a base station and at least one user, and the base station and the user are communicatively connected.

9. A computer storage medium, It is characterized in that The computer storage medium stores a computer program; when the computer program is executed on a computer, the computer executes the pilot allocation method for millimeter wave frequency band joint communication and positioning as claimed in claim 1.

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