CN110865330A - Method for quickly tracking beam azimuth in wireless virtual reality system - Google Patents

Method for quickly tracking beam azimuth in wireless virtual reality system Download PDF

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CN110865330A
CN110865330A CN201911214259.5A CN201911214259A CN110865330A CN 110865330 A CN110865330 A CN 110865330A CN 201911214259 A CN201911214259 A CN 201911214259A CN 110865330 A CN110865330 A CN 110865330A
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helmet
remote radio
radio unit
azimuth
azimuth angle
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CN110865330B (en
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王旭
陈南希
张晓林
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Shanghai Institute of Microsystem and Information Technology of CAS
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Shanghai Institute of Microsystem and Information Technology of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
    • G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
    • G01S3/14—Systems for determining direction or deviation from predetermined direction
    • G01S3/143—Systems for determining direction or deviation from predetermined direction by vectorial combination of signals derived from differently oriented antennae
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention provides a method for quickly tracking a beam azimuth in a wireless virtual reality system, which comprises the following steps: selecting a current working remote radio unit, and taking the other remote radio units as search remote radio units in turn; the current working remote radio unit transmits audio and video information, and searches for channel detection signals of a plurality of wave beam directions emitted by the remote radio unit to the helmet; the helmet acquires an azimuth angle of a search radio remote unit; updating an optimal estimate of the position of the helmet; adjusting the beam azimuth angle of the current working remote radio unit according to the optimal estimation; and (4) increasing the current moment, updating the searching radio remote unit, searching the beam again, and repeating the steps. The searching radio frequency remote unit adopted by the method of the invention is not responsible for audio and video information transmission, so the beam scanning can be carried out uninterruptedly, thereby reaching the highest beam scanning frequency and leading the current working radio frequency remote unit to be capable of transmitting data at high speed when the user moves.

Description

Method for quickly tracking beam azimuth in wireless virtual reality system
Technical Field
The invention relates to the field of virtual reality, in particular to a method for quickly tracking a beam azimuth angle in a wireless virtual reality system.
Background
As a novel human-computer interaction technology, a virtual reality system has been rapidly developed in recent years. Traditional human-computer interaction technologies, such as mice, keyboards, touch screens, etc., are two-dimensional. The virtual reality system can simulate information of a three-dimensional space through a high-performance computer and transmit the information to a user, and the user can experience a three-dimensional world completely simulated by the computer after wearing a special helmet. Because the objects seen in daily life of people are three-dimensional, the reality of analog simulation is greatly improved by the virtual reality system, and the user experience is obviously improved.
The virtual reality system mainly comprises a host and a helmet. The host computer is a high-performance computer and is used for generating high-definition video and high-fidelity audio. The helmet receives and plays the audio and video information sent by the host. In order to transmit the audio-video information generated by the host computer to the helmet, a wired mode or a wireless mode can be adopted. The wired mode is relatively simple, and a physical entity cable is directly connected between the host and the helmet. This approach has found application in many virtual reality systems. However, this physical line limits the freedom of movement for the user. Especially when there are multiple subscribers, the cables of different subscribers may be intertwined with each other. The wireless mode cancels cables, and utilizes the wireless communication technology to transmit audio and video information, so that users can move freely. Because the data volume of high-definition video and high-fidelity audio generated by the host computer is large, the wireless virtual reality system generally adopts the millimeter wave communication technology. This leads to two important problems in wireless virtual reality systems: firstly, the signal occlusion problem; the second is the beam tracking problem caused by the user movement.
Millimeter wave communication has a short wavelength, so that the diffraction capability of signals is poor, and once an obstacle is met, the signal quality is rapidly reduced, namely, millimeter wave signals are shielded by the obstacle. To solve this problem, in patent application No. CN201910809798.7, a wireless virtual reality system based on distributed antennas is proposed. The main method is to arrange one Radio Remote Unit (RRUs) at each of 8 vertices of a room. If an obstacle appears between the remote radio unit at one vertex and the helmet, the remote radio unit can be quickly switched to other remote radio units. In a virtual reality system, time delay is a key index. Because the user feels vertigo once the time delay exceeds 20 ms. The architecture of the distributed antenna minimizes the time required to switch the remote radio unit.
Due to high frequency band and large path loss of millimeter wave communication, the intensity of a received signal needs to be improved by using a beam forming technology, that is, a radio remote unit emits a narrow beam to align with a helmet. If the user moves the position, the azimuth of the beam needs to be readjusted to track the change in the user's position to keep the beam covering the helmet all the time. In the wireless virtual reality system, a user can move freely, so the wireless virtual reality system not only needs to detect obstacles, but also needs to track the change of the position of the helmet so as to continuously adjust the azimuth angle of a beam emitted by the radio remote unit. The faster the user moves, the shorter the beam azimuth update needs to be completed.
The wireless virtual reality system based on the distributed antenna proposed by the above-mentioned patent adopts a traditional beam tracking method, that is, the remote radio unit is to specially divide a certain time-frequency resource for beam scanning when transmitting data, so as to adjust the azimuth angle of the beam transmitted by the remote radio unit. The more frequent the beam scanning is performed, the more timely and accurate the tracking of the position of the helmet is, but the more time-frequency resources are used for the beam scanning. In order to be able to have enough time-frequency resources for the transmission of high definition video and high fidelity audio, beam scanning cannot be performed too often. This means that existing wireless virtual reality systems based on distributed antennas may not be able to keep up with the rapid changes in the position of the helmet when the communication transmission rate is high. At this time, the beam emitted by the remote radio unit deviates from the optimal direction angle, so that the intensity of the received signal is reduced, and even the position of the helmet may be completely missed.
Disclosure of Invention
The invention provides a method for quickly tracking a beam azimuth in a wireless virtual reality system, which enables the wireless virtual reality system to transmit data at a high speed when a user moves.
In order to achieve the above object, the present invention provides a method for quickly tracking a beam azimuth in a wireless virtual reality system, which is used for a wireless virtual reality system based on a distributed antenna, wherein the wireless virtual reality system is provided with 1 helmet and 8 remote radio units in a room, and the method for quickly tracking the beam azimuth comprises:
step S0: selecting a current working remote radio unit p, taking the rest remote radio units 1, p-1, p +1, 8 as a search remote radio unit q in turn along with the increment of the time, then setting the current time t as 0, and initializing the optimal estimation of the helmet position
Figure BDA0002299046360000031
And its construction matrix A0Structural vector b0Then t is increased to 1;
step S1: the method comprises the steps that a current working radio remote unit p and a helmet are used for transmitting high-definition video and high-fidelity audio signals, and meanwhile, a searching radio remote unit q at the current moment is used for transmitting channel detection signals in (2A +1) × (2B +1) wave beam directions to the helmet, wherein A and B are positive integers;
step S2: after receiving the channel detection signal, the helmet acquires an azimuth angle of the searching remote radio unit q at the current moment and feeds back the azimuth angle to the host;
step S3: updating the optimal estimation of the helmet position at the current moment;
step S4: adjusting the beam azimuth angle of the currently operating remote radio unit p according to the optimal estimation in the step S3;
step S5: updating the searching remote radio unit q at the current moment when the value of the current moment t is increased progressively, and predicting the azimuth angle from the searching remote radio unit q at the current moment to the helmet according to the space coordinate of the searching remote radio unit q and the optimal estimation in the step S3;
step S6: performing the beam search again in the vicinity of the azimuth angle of the search remote radio unit q to the helmet in the step S5, and repeating the steps S1-S4;
step S7: the above steps S5-S6 are repeated.
In the step S1, the transmitted channel soundingThe horizontal component of the beam direction of the measurement signal is
Figure BDA0002299046360000032
A vertical component of
Figure BDA0002299046360000033
Figure BDA0002299046360000034
To search for the horizontal component of the azimuth of the remote radio unit q to the helmet,
Figure BDA0002299046360000035
in order to search for the vertical component of the azimuth angle from the remote radio unit q to the helmet, delta phi, delta theta are search step lengths,
and in the step S5, the azimuth angle from the remote radio unit q to the helmet is predicted according to the helmet position at the last time t-1,
the calculation formula of the horizontal component of the azimuth angle from the remote radio unit q to the helmet R1 is:
Figure BDA0002299046360000036
the calculation formula for searching the vertical component of the azimuth angle from the remote radio unit q to the helmet is as follows:
Figure BDA0002299046360000041
wherein ,
Figure BDA0002299046360000042
for the helmet position at the previous time t-1, (x)q,yq,zq) To search for the spatial coordinates of the remote radio unit q.
In step S1, before transmitting the channel sounding signal, a spreading operation is performed, wherein the spreading sequence uses Zadoff-Chu sequences, and the roots of the Zadoff-Chu sequences used by different remote radio units are different from each other, and the bandwidths of the high definition video and high fidelity audio signals after spreading are the same as the bandwidth of the channel sounding signal.
In the step S2, it is determined whether an obstacle exists between the remote radio unit q and the helmet according to the strength of the received channel sounding signal, if the strength of the received channel sounding signal is greater than a threshold, the obstacle does not exist between the remote radio unit q and the helmet, and a beam with the highest received signal strength is selected as the azimuth angle of the remote radio unit q at the current time, otherwise, the azimuth angle from the remote radio unit q to the helmet predicted in the step S5 is used as the azimuth angle of the remote radio unit q at the current time.
In step S2, the helmet performs matching correlation on the received spread spectrum signal through a multiplier and an adder in the analog circuit, then samples the data after matching correlation by using the analog-to-digital converter, and selects the beam direction with the maximum received signal intensity by calculating the energy of the data obtained by sampling.
In step S3, the optimal estimation of the helmet position is:
Figure BDA0002299046360000043
wherein
At＝At-1+ΔA(φq,t,θq,t,φq,t-1,θq,t-1)
Figure BDA0002299046360000044
Figure BDA0002299046360000045
f1(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1cos2φq,t-1-sin2θq,tcos2φq,t
f2(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sinφq,t-1cosφq,t-1-sin2θq,tsinφq,tcosφq,t
f3(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1cosφq,t-1-sinθq,tcosθq,tcosφq,t
f4(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sin2φq,t-1-sin2θq,tsin2φq,t
f5(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1sinφq,t-1-sinθq,tcosθq,tsinφq,t
f6(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-sin2θq,t-1
wherein ,φq,t,θq,tIndicates the azimuth angle phi of the search RRU q at the current time tq,t-1,θq,t-1Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x)q,yq,zq) Represents the spatial coordinates, Δ A (φ), of the search RRU qq,t,θq,t,φq,t-1,θq,t-1) Only the azimuth angles of the remote radio unit q at the current time t and the last time t-1 are searched.
In the step S4, the optimal estimation of the helmet position in the step S3 is taken as the helmet position at the current time t, and the azimuth of the currently operating remote radio unit p is adjusted according to the helmet position at the current time t,
the calculation formula of the azimuth angle of the current working remote radio unit p is as follows:
Figure BDA0002299046360000051
Figure BDA0002299046360000052
wherein ,
Figure BDA0002299046360000053
for the helmet position at the current time t, (x)p,yp,zp) And the position coordinates of the current working remote radio unit p.
The method for quickly tracking the beam azimuth in the wireless virtual reality system detects the position of a helmet by utilizing the searching remote radio unit for detecting obstacles, and the current working remote radio unit for transmitting high-definition video and high-fidelity audio does not perform beam scanning. Because the searching remote radio unit is not responsible for the transmission of the audio and video information, the beam scanning can be carried out uninterruptedly, thereby reaching the highest beam scanning frequency, and the current working remote radio unit can also transmit data at high speed when the user moves.
In addition, the method for quickly tracking the beam azimuth in the wireless virtual reality system has the advantages that the bandwidth of the channel detection signal after the channel detection signal is spread is the same as the bandwidth of high-definition video and high-fidelity audio signals, so that the signals with two bandwidths do not need to be respectively adapted in a radio remote unit, and a hardware circuit is simplified; meanwhile, if the length of the spreading sequence is Q, the energy of the remote radio unit when transmitting the channel sounding signal may be 1/Q before spreading. When Q is 100, the total transmission power of the 8 remote radio units after spreading is only 13.4% of the total transmission power before spreading. Thereby significantly reducing the power consumption of the host.
In addition, the method for quickly tracking the beam azimuth angle in the wireless virtual reality system fully utilizes the information of the previous moment to predict the azimuth angle, so that the searching range of the beam at the current moment t is reduced, the beam searching is not required to be carried out in the whole space, and the beam searching is only carried out near the predicted position, so that the beam searching speed is accelerated.
Moreover, because the method for quickly tracking the beam azimuth in the wireless virtual reality system only updates the azimuth of one searching remote radio unit at one moment, the calculation matrix A is used for calculating the azimuth of the beam azimuthtAnd vector btIncremental calculation can be adopted, and the calculation amount is effectively reduced.
Drawings
Fig. 1 is a schematic diagram of an application environment provided by a method for fast tracking of beam azimuth in a wireless virtual reality system according to the present invention.
Detailed Description
The present invention will be further described with reference to the following specific examples. It should be understood that the following examples are illustrative only and are not intended to limit the scope of the present invention.
As shown in fig. 1, consider a wireless virtual reality system based on distributed antennas. The wireless virtual reality system is provided with 1 host computer, 1 helmet R1 and 8 RRU R2 in a room, the serial numbers are 1,2, 8, the spatial coordinates of the kth RRU R2 are used (x)k,yk,zk) And (4) showing. The host computer is a computer and is responsible for generating high-definition video and high-fidelity audio. The high-speed data transmission is carried out between 1 radio remote unit R2 selected from 8 radio remote units R2 and the helmet R1, and the high-speed data transmission is responsible for transmitting high-definition video and high-fidelity audio generated by a host computer to the helmet R1. The other 7 remote radio units R2 continuously send channel sounding signals for detecting the channel quality from each remote radio unit R2 to the helmet R1. Once an obstacle appears before the radio remote unit R2 currently responsible for high-speed data transmission and the helmet R1, the radio remote unit with the best channel quality in the remaining 7 radio remote units R2 is quickly switched to ensure uninterrupted transmission of audio and video information.
The invention provides a method for quickly tracking a beam azimuth in a wireless virtual reality system, which is used for the wireless virtual reality system based on a distributed antenna, and the wireless virtual reality system comprises a plurality of remote radio units R2, wherein one remote radio unit R2 is responsible for transmitting high-definition video and high-fidelity audio without beam scanning and is called as a current working remote radio unit, and the other 7 remote radio units R2 transmit channel detection signals to detect the position of a helmet R1 and are called as search remote radio units. Since the search remote radio unit R2 is not responsible for the transmission of audio/video information, beam scanning can be performed continuously, so as to reach the highest beam scanning frequency, which enables the currently operating remote radio unit to transmit data at high speed even when the user moves.
The method for quickly tracking the beam azimuth in the wireless virtual reality system can be divided into two stages of initialization and quick beam tracking, and specifically comprises the following steps:
when the current time t is 0, the initialization phase is performed.
Step S0: all the remote radio units R2 are initialized to select the operating remote radio unit p. Subsequent initialization of optimal estimation of helmet position
Figure BDA0002299046360000071
And its construction matrix A0Structural vector b0。
All the remote radio units R2 are initialized, which specifically includes:
all of the remote radio units R2 are numbered 1, 2. Sequentially sending channel detection signals in all possible wave beam directions by all radio remote units R2 by taking delta phi and delta theta as search steps to carry out exhaustive search, selecting the wave beam direction with the maximum received signal intensity as an azimuth angle of the radio remote units during initialization after the helmet R1 receives the channel detection signals, and using phi as a horizontal component of the azimuth anglek,0Expressed by the vertical component θk,0And (4) showing. Selecting one radio remote unit R2 as a current working radio remote unit p, and taking the radio remote units R2 with the rest numbers of 1, p-1, p +1, 8 as search radio remote units q in turn along with the increment of time. The set of indices for all the remote radio units is denoted by Ω ═ 1, …, p-1, p + 1.
Considering that all the remote radio units are located at the vertex of the room, each remote radio unit only needs to search 1/4 planes in the horizontal direction, namely 90 degrees; only the upper or lower half-space, i.e. 90 °, has to be searched in the vertical direction.
Thus, during initialization, each remote radio unit needs to search
Figure BDA0002299046360000072
A beam direction wherein
Figure BDA0002299046360000073
Is an rounding-up function.
The optimal estimate of the initialized helmet position is:
Figure BDA0002299046360000081
wherein the construction matrix A of the initialized helmet position estimation0Construction of vector b0Respectively as follows:
Figure BDA0002299046360000082
Figure BDA0002299046360000083
φk,0,θk,0denotes the azimuth angle of the k-th remote radio unit, (x)k,yk,zk) Representing spatial coordinates of a k-th remote radio unit;
when the current time t is greater than 0, the method is a beam tracking stage, and specifically comprises the following steps:
step S1: the high-speed transmission of high-definition video and high-fidelity audio signals is carried out by using the current working remote radio unit p and the helmet R1, and meanwhile, channel detection signals in (2A +1) × (2B +1) beam directions are transmitted to the helmet R1 by using the searching remote radio unit q at the current moment so as to carry out beam searching.
In the step S1, the transmission is performedThe horizontal component of the beam direction of the channel sounding signal is
Figure BDA0002299046360000084
A vertical component of
Figure BDA0002299046360000085
Figure BDA0002299046360000086
To search for the horizontal component of the azimuth of the remote radio unit q to the helmet R1,
Figure BDA0002299046360000087
to search for the vertical component of the azimuth of the remote radio unit q to the helmet R1, Δ Φ, Δ θ are the search steps, Δ Φ, Δ θ are typically 5 ° or 10 °, a, B are positive integers, and a, B are typically 1,2 or 3.
Typically, the bandwidth of the channel sounding signal before spreading is much smaller than the bandwidth of high definition video and high fidelity audio signals. Let the bandwidth of the latter be Q times the bandwidth of the former, where Q is an integer, and a typical value of Q is 100. Patent CN201910809798.7 uses two shaping filters and a switch to support the transmission of both bandwidth signals simultaneously. In the method for quickly tracking the wave beam azimuth angle in the wireless virtual reality system, before the channel detection signal is transmitted, spread spectrum operation is firstly carried out, a Zadoff-Chu sequence is used as a spread spectrum sequence, the length is Q, the root of the Zadoff-Chu sequence used by different radio frequency remote units is different, and the bandwidth of the channel detection signal after spread spectrum is the same as that of the high-definition video and high-fidelity audio signal. Thus, the present invention requires only one shaping filter and no switch.
Therefore, the invention realizes two advantages by spreading the channel detection signal: firstly, the bandwidth of the channel detection signal after the spread spectrum is the same as that of the high-definition video and high-fidelity audio signals, so that two shaping filters and a switch are not needed to be used in the radio remote unit to respectively adapt to the signals with the two bandwidths, and the hardware circuit is simplified. First, theSecond, the helmet R1 can accumulate energy across the entire spreading sequence when detecting a spread spectrum signal. For a spreading sequence of length Q, the signal-to-noise ratio is Q times that before spreading. This means that the transmission energy of the remote radio unit can be 1/Q before spreading. Suppose the transmission power of the remote radio unit is PRRU. If not spread, the total transmitting power of 8 remote radio units is 8PRRU. After spreading, the total transmission power of 8 RRUs is (1+7/Q) PRRU. If Q is 100, the total transmit power after spreading is only 13.4% of the total transmit power before spreading.
Step S2: after receiving the channel sounding signal, the helmet R1 selects a beam with the highest received signal strength as an azimuth angle of the remote radio unit q at the current time, and feeds back the azimuth angle to the host.
The helmet R1 performs matching correlation on the received spread spectrum signal through a multiplier and an adder in the analog circuit, then samples the data after matching correlation by using the analog-to-digital converter, and selects the beam direction with the maximum received signal intensity by calculating the energy of the data obtained by sampling. Wherein the horizontal component of the azimuth angle of the RRU q at the current time t is represented by phiq,tExpressed by the vertical component θq,tAnd (4) showing.
In step S2, when the current time t > 0, it is determined whether an obstacle exists between the remote search unit q and the helmet R1 according to the strength of the received channel sounding signal, and if the strength of the received channel sounding signal is greater than a threshold, no obstacle exists between the remote search unit q and the helmet R1, and a beam with the highest received signal strength is selected as the azimuth angle of the remote search unit q at the current time. On the contrary, if there is an obstacle between the remote radio unit q and the helmet R1, the signal may be very weak even if the beam with the highest received signal strength is used, in this case, the command is directly sent
Figure BDA0002299046360000091
Namely the stepThe azimuth angle of the search remote radio unit q to the helmet R1 predicted in S5 is used as the azimuth angle of the search remote radio unit q at the current time.
The helmet carries out matching correlation on the received spread spectrum signal in the analog circuit, and solves the problem that the power consumption of an analog-to-digital converter for a broadband signal is higher than that of an analog-to-digital converter for a narrowband signal for the helmet. This is because the matched correlation essentially multiplies and adds a sequence, which can be done with multipliers and adders in analog circuits, respectively. Thus, the analog-to-digital converter only needs to sample the data after matching the correlation. The symbol rate of the data has now dropped to exactly the same as the signal that was not spread and therefore the power consumption of the analog to digital converter is also the same as the signal that was not spread.
Step S3: updating the optimal estimation of the helmet position at the current moment;
wherein, in the step S3, the optimal estimation of the helmet position at the current time t
Figure BDA0002299046360000101
The calculation process of (2) is as follows:
after the helmet R1 receives the azimuth angle fed back by the remote radio unit q, the host updates the helmet position according to the latest measurement result. According to geometric theory, two straight lines are sufficient to determine the position of a point. In practice, the estimation of the azimuth angle is inevitable to have errors, so more straight lines are needed to reduce the estimation error.
Order to
Figure BDA0002299046360000102
Indicating the position of the helmet at time t, dkIndicating the distance from the helmet to the line where the beam of the kth remote radio unit is located. Then
Figure BDA0002299046360000103
The sum of the distances from the helmet R1 to all the straight lines is
Figure BDA0002299046360000104
If there is no measurement error, then d20. In order to find an optimal estimate of the position of the helmet R1, in the presence of measurement errors, the derivation of the above equation,
Figure BDA0002299046360000111
Figure BDA0002299046360000112
Figure BDA0002299046360000113
order to
Figure BDA0002299046360000114
The following equation can be obtained
Figure BDA0002299046360000115
wherein
Figure BDA0002299046360000116
Figure BDA0002299046360000121
Therefore, an optimal estimation of the helmet position
Figure BDA0002299046360000122
Comprises the following steps:
Figure BDA0002299046360000123
except for RRU q, the rest RRUs do not update the estimation of the azimuth angle at the time t, namely phik,t＝φk,t-1,
Figure BDA0002299046360000124
and θk,t＝θk,t-1,
Figure BDA0002299046360000125
Therefore, to reduce the amount of calculation, At and btCan be written as follows
At＝At-1+ΔA(φq,t,θq,t,φq,t-1,θq,t-1)
Figure BDA0002299046360000126
Wherein, Δ A (φ)q,t,θq,t,φq,t-1,θq,t-1) Only with respect to the azimuth of the remote radio unit q at time t and time t-1,
Figure BDA0002299046360000127
f1(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1cos2φq,t-1-sin2θq,tcos2φq,t
f2(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sinφq,t-1cosφq,t-1-sin2θq,tsinφq,tcosφq,t
f3(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1cosφq,t-1-sinθq,tcosθq,tcosφq,t
f4(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sin2φq,t-1-sin2θq,tsin2φq,t
f5(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1sinφq,t-1-sinθq,tcosθq,tsinφq,t
f6(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-sin2θq,t-1
wherein ,φq,t,θq,tIndicates the azimuth angle phi of the search RRU q at the current time tq,t-1,θq,t-1Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x)q,yq,zq) Representing the spatial coordinates of the remote radio unit q being searched.
Step S4: according to the optimal estimation in the step S3
Figure BDA0002299046360000131
Adjusting the azimuth angle of the current working remote radio unit p;
in the step S4, the optimal estimation of the helmet position in the step S3 is taken as the helmet position at the current time t, and the azimuth of the currently operating remote radio unit p is adjusted according to the helmet position at the current time t,
the calculation formula of the azimuth angle of the current working remote radio unit p is as follows:
Figure BDA0002299046360000132
Figure BDA0002299046360000133
wherein ,
Figure BDA0002299046360000134
for the helmet position at the current time t, (x)p,yp,zp) And the position coordinates of the current working remote radio unit p.
Then, another searching remote unit becomes the searching remote unit q at the current moment, thereby updating the searching remote unit q at the current moment.
Step S5: when the value of the current time t is increased, the search remote radio unit q at the current time is updated, and the optimal estimation in the step S3 (the optimal estimation is the helmet position at the previous time t-1) is performed according to the spatial coordinates of the search remote radio unit q
Figure BDA0002299046360000135
) The new azimuth angle from the remote radio unit q to the helmet R1 at the current time is predicted.
The position of the helmet R1 may change from time t-1 to time t, so that the remote radio unit q needs to transmit beams to multiple adjacent directions, i.e., beam scanning. Since the position of the helmet R1 does not change dramatically at both times, the beam direction transmitted at time t is searched for a small range in the vicinity thereof with reference to the position at time t-1. Therefore, from the estimation of the position of the helmet R1 at time t-1, the azimuth angle of the RRU q to the helmet R1 can be predicted.
Predicting the azimuth angle from the search remote radio unit q to the helmet according to the helmet position at the last time t-1, wherein the horizontal component of the azimuth angle from the search remote radio unit q to the helmet R1 is as follows:
Figure BDA0002299046360000141
the vertical component of the azimuth angle from the search remote radio unit q to the helmet R1 is:
Figure BDA0002299046360000142
wherein ,
Figure BDA0002299046360000143
for the helmet position at the last time t-1 (i.e., the optimal estimate of the helmet position in said step S3), (x)q,yq,zq) To search for the spatial coordinates of the remote radio unit q.
Step S6: the beam search is performed again in the vicinity of the azimuth angle of the remote radio unit q to the helmet R1 searched in the step S5, and the above-described steps S1 to S4 are repeated.
Step S7: the above steps S5-S6 are repeated.
The above embodiments are merely preferred embodiments of the present invention, which are not intended to limit the scope of the present invention, and various changes may be made in the above embodiments of the present invention. All simple and equivalent changes and modifications made according to the claims and the content of the specification of the present application fall within the scope of the claims of the present patent application. The invention has not been described in detail in order to avoid obscuring the invention.

Claims (7)

1. A method for quickly tracking the azimuth of a beam in a wireless virtual reality system, which is used for the wireless virtual reality system based on a distributed antenna, wherein the wireless virtual reality system is provided with 1 helmet and 8 remote radio units in a room, and the method for quickly tracking the azimuth of the beam comprises the following steps:
step S0: selecting a current working remote radio unit p, taking the rest remote radio units 1, p-1, p +1, 8 as a search remote radio unit q in turn along with the increment of the time, then setting the current time t as 0, and initializing the optimal estimation of the helmet position
Figure FDA0002299046350000011
And its construction matrix A0Structural vector b0Then t is increased to 1;
step S1: the method comprises the steps that a current working radio remote unit p and a helmet are used for transmitting high-definition video and high-fidelity audio signals, and meanwhile, a searching radio remote unit q at the current moment is used for transmitting channel detection signals in (2A +1) × (2B +1) wave beam directions to the helmet, wherein A and B are positive integers;
step S2: after receiving the channel detection signal, the helmet acquires an azimuth angle of the searching remote radio unit q at the current moment and feeds back the azimuth angle to the host;
step S3: updating the optimal estimation of the helmet position at the current moment;
step S4: adjusting the beam azimuth angle of the currently operating remote radio unit p according to the optimal estimation in the step S3;
step S5: updating the searching remote radio unit q at the current moment when the value of the current moment t is increased progressively, and predicting the azimuth angle from the searching remote radio unit q at the current moment to the helmet according to the space coordinate of the searching remote radio unit q and the optimal estimation in the step S3;
step S6: performing the beam search again in the vicinity of the azimuth angle of the search remote radio unit q to the helmet in the step S5, and repeating the steps S1-S4;
step S7: the above steps S5-S6 are repeated.
2. The method for fast tracking beam azimuth angle in wireless virtual reality system according to claim 1, wherein in step S1, the horizontal component of the beam direction of the transmitted channel sounding signal is
Figure FDA0002299046350000012
A vertical component of
Figure FDA0002299046350000013
Figure FDA0002299046350000014
To search for the horizontal component of the azimuth of the remote radio unit q to the helmet,
Figure FDA0002299046350000015
in order to search for the vertical component of the azimuth angle from the remote radio unit q to the helmet, delta phi, delta theta are search step lengths,
and in the step S5, the azimuth angle from the remote radio unit q to the helmet is predicted according to the helmet position at the last time t-1,
the calculation formula of the horizontal component of the azimuth angle from the remote radio unit q to the helmet R1 is:
Figure FDA0002299046350000021
the calculation formula for searching the vertical component of the azimuth angle from the remote radio unit q to the helmet is as follows:
Figure FDA0002299046350000022
wherein ,
Figure FDA0002299046350000023
for the helmet position at the previous time t-1, (x)q,yq,zq) To search for the spatial coordinates of the remote radio unit q.
3. The method for fast tracking azimuth of beam in wireless virtual reality system according to claim 1, wherein in step S1, before transmitting the channel sounding signal, a spreading operation is performed, the spreading sequence uses Zadoff-Chu sequence, and the roots of the Zadoff-Chu sequence used by different remote radio units are different, and the bandwidth of the channel sounding signal after spreading is the same as the bandwidth of the high definition video and high fidelity audio signal.
4. The method as claimed in claim 1, wherein in the step S2, it is determined whether there is an obstacle between the remote radio unit q and the helmet according to the strength of the received channel sounding signal, if the strength of the received channel sounding signal is greater than a threshold, there is no obstacle between the remote radio unit q and the helmet, and a beam with the highest received signal strength is selected as the azimuth of the remote radio unit q at the current time, otherwise, the azimuth from the remote radio unit q to the helmet predicted in the step S5 is used as the azimuth of the remote radio unit q at the current time.
5. The method for fast tracking azimuth of beam in wireless virtual reality system according to claim 4, wherein in step S2, the helmet performs matching correlation on the received spread spectrum signal through a multiplier and an adder in an analog circuit, then samples the data after matching correlation by using an analog-to-digital converter, and selects the beam direction with the maximum received signal strength by calculating the energy of the sampled data.
6. The method for fast tracking azimuth angle of beam in wireless virtual reality system according to claim 1, wherein in step S3, the optimal estimation of the position of the helmet is:
Figure FDA0002299046350000031
wherein
At＝At-1+ΔA(φq,t,θq,t,φq,t-1,θq,t-1)
Figure FDA0002299046350000032
Figure FDA0002299046350000033
f1(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1cos2φq,t-1-sin2θq,tcos2φq,t
f2(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sinφq,t-1cosφq,t-1-sin2θq,tsinφq,tcosφq,t
f3(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1cosφq,t-1-sinθq,tcosθq,tcosφq,t
f4(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-1sin2φq,t-1-sin2θq,tsin2φq,t
f5(φq,t,θq,t,φq,t-1,θq,t-1)＝sinθq,t-1cosθq,t-1sinφq,t-1-sinθq,tcosθq,tsinφq,t
f6(φq,t,θq,t,φq,t-1,θq,t-1)＝sin2θq,t-sin2θq,t-1
wherein ,φq,t,θq,tIndicates the azimuth angle phi of the search RRU q at the current time tq,t-1,θq,t-1Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x)q,yq,zq) Represents the spatial coordinates, Δ A (φ), of the search RRU qq,t,θq,t,φq,t-1,θq,t-1) Only the azimuth angles of the remote radio unit q at the current time t and the last time t-1 are searched.
7. The method for fast tracking azimuth of beam in wireless virtual reality system according to claim 1, wherein in step S4, the optimal estimation of helmet position in step S3 is used as helmet position at current time t, and the azimuth of the currently operating RRU p is adjusted according to the helmet position at current time t,
the calculation formula of the azimuth angle of the current working remote radio unit p is as follows:
Figure FDA0002299046350000041
Figure FDA0002299046350000042
wherein ,
Figure FDA0002299046350000043
for the helmet position at the current time t, (x)p,yp,zp) And the position coordinates of the current working remote radio unit p.
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