CN110865330B - Rapid tracking method for wave beam azimuth angle in wireless virtual reality system - Google Patents
Rapid tracking method for wave beam azimuth angle in wireless virtual reality system Download PDFInfo
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- 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
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Abstract
The invention provides a fast tracking method of a wave beam azimuth angle in a wireless virtual reality system, which comprises the following steps: selecting a current working remote radio unit, and alternately taking the rest remote radio units as search remote radio units; the method comprises the steps that an audio and video information transmission is carried out by a current working remote radio unit, and channel detection signals in multiple beam directions are transmitted to a helmet by the remote radio unit; the helmet acquires an azimuth angle for searching the remote radio unit; updating an optimal estimate of the helmet position; adjusting the beam azimuth angle of the current working remote radio unit according to the optimal estimation; and increasing the current moment, updating the searching remote radio unit, searching the wave beam again, and repeating the steps. The searching remote radio unit adopted by the method is not responsible for audio and video information transmission, so that the beam scanning can be carried out uninterruptedly, thereby achieving the highest beam scanning frequency and enabling the current working remote radio unit to also transmit data at high speed when a user moves.
Description
Technical Field
The invention relates to the field of virtual reality, in particular to a fast tracking method of a wave beam azimuth angle in a wireless virtual reality system.
Background
As a novel man-machine interaction technology, a virtual reality system has been rapidly developed in recent years. Traditional man-machine interaction technologies, such as mice, keyboards, touch screens, etc., are two-dimensional. The virtual reality system can simulate three-dimensional space information through a high-performance computer and transmit the three-dimensional space 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 by people in daily life are three-dimensional, the reality of the simulation is greatly improved by the virtual reality system, and therefore the user experience is remarkably improved.
The virtual reality system mainly comprises a host and a helmet. The host is a high-performance computer 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 and video information generated by the host to the helmet, a wired mode or a wireless mode can be adopted. The wired mode is relatively simple, and a physical 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 free movement of the user. Especially when there are multiple users, the cables of different users may also be intertwined. The wireless mode eliminates the cable and utilizes the wireless communication technology to transmit audio and video information, so that the user can freely move. Because the data volume of the high-definition video and the high-fidelity audio generated by the host is large, the wireless virtual reality system generally adopts the millimeter wave communication technology. This results in two important problems in wireless virtual reality systems: firstly, the signal shielding problem; and secondly, beam tracking caused by user movement.
Millimeter wave communication has poor signal diffraction capability due to shorter wavelength, and once an obstacle is encountered, the signal quality is drastically reduced, i.e. the millimeter wave signal is blocked by the obstacle. To solve this problem, in patent application CN201910809798.7, a wireless virtual reality system based on a distributed antenna is proposed. The main method is that a remote radio unit (remote radio units, RRUs) is arranged at each of 8 vertexes of a room. If an obstacle appears between the remote radio unit at a certain vertex and the helmet, the remote radio unit can be quickly switched to other remote radio units. In a virtual reality system, latency is a key indicator. Because once the delay exceeds 20 milliseconds, the user will have a sense of dizziness. The architecture of the distributed antenna minimizes the time required to switch remote units.
Millimeter wave communication has high frequency band and high path loss, and the intensity of a received signal needs to be improved by utilizing a beam forming technology, namely, a radio remote unit transmits a narrow beam to be aligned with a helmet. If the user moves position, the azimuth of the beam needs to be readjusted to track the change in user position to keep the beam always able to cover the helmet. In the wireless virtual reality system, a user can freely move, so that the wireless virtual reality system is required to detect obstacles and track the change of the position of the helmet at the same time so as to continuously adjust the azimuth angle of a wave beam sent by the remote radio unit. The faster the user moves, the shorter the time required to complete updating of the beam azimuth.
The wireless virtual reality system based on the distributed antenna proposed by the above-mentioned patent adopts a traditional beam tracking method, namely, a radio remote unit is required to specially divide certain time-frequency resources for beam scanning when transmitting data, so as to adjust the azimuth angle of the beam transmitted by the radio remote unit. The more frequent the beam scanning is, the more timely and accurate the tracking of the helmet position is, but at the same time the more time-frequency resources are used for the beam scanning. Beam scanning is not possible too often in order to have enough time-frequency resources for transmission of high definition video and high fidelity audio. This means that existing wireless virtual reality systems based on distributed antennas may not keep up with rapid changes in helmet position at higher communication transmission rates. At this time, the beam emitted by the remote radio unit may deviate from the optimal direction angle, so that the strength of the received signal may be reduced, and even the helmet may be missed completely.
Disclosure of Invention
The invention provides a fast tracking method of a wave beam azimuth angle 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 fast tracking method of a beam azimuth in a wireless virtual reality system, which is used in a wireless virtual reality system based on a distributed antenna, wherein the wireless virtual reality system is installed with 1 helmet and 8 remote radio units in a room, and the fast tracking method is characterized in that the fast tracking method comprises:
step S0: selecting a current working remote radio unit p, and using the rest remote radio units 1, p-1, p+1, 8 as search remote radio units q in turn along with the increment of time, then setting the current time t to 0, and initializing the optimal estimation of the helmet position
And a construction matrix A thereof 0 Construction vector b 0 Then increasing t to 1;
step S1: transmitting high-definition video and high-fidelity audio signals by using the current working remote radio unit p and the helmet, and transmitting channel detection signals in (2A+1) x (2B+1) beam directions to the helmet by using the current time searching remote radio unit q, wherein A and B are positive integers;
step S2: after receiving the channel detection signal, the helmet acquires the azimuth angle of the searching remote radio unit q at the current moment and feeds the azimuth angle back 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 current working remote radio unit p according to the optimal estimation in the step S3;
step S5: updating the searching radio remote unit q at the current moment when the value of the current moment t is increased, and predicting the azimuth angle from the searching radio remote unit q at the current moment to the helmet according to the space coordinate of the searching radio remote unit q and the optimal estimation in the step S3;
step S6: carrying out beam searching again in the vicinity of the azimuth angle from the searching radio remote unit q to the helmet in the step S5, and repeating the steps S1-S4;
step S7: repeating the steps S5-S6.
In said step S1, the horizontal component of the beam direction of the transmitted channel-sounding signal is
The vertical component is +.>
To search for the horizontal component of the azimuth of the remote unit q to the helmet, < >>
To search for the vertical component of the azimuth of the remote unit q to the helmet, delta phi, delta theta is the search step,
and in the step S5, the azimuth angle from the search remote radio unit q to the helmet is predicted according to the helmet position at the previous 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 as follows:
the calculation formula for searching the vertical component of the azimuth angle from the remote radio unit q to the helmet is as follows:
wherein ,
the helmet position at the last time t-1, (x) q ,y q ,z q ) To search for the spatial coordinates of the remote radio unit q.
In the step S1, before the channel sounding signal is transmitted, a spreading operation is performed, a Zadoff-Chu sequence is used as a spreading sequence, the roots of the Zadoff-Chu sequences used by different remote radio units are different, and after the spreading, the bandwidths of the high-definition video and high-fidelity audio signals are the same as the bandwidths of the channel sounding signal.
In the step S2, whether an obstacle exists between the search remote radio unit q and the helmet is determined according to the intensity of the received channel detection signal, if the intensity of the received channel detection signal is greater than a threshold, no obstacle exists between the search remote radio unit q and the helmet, a beam with the highest intensity of the received signal is selected as an azimuth angle of the search remote radio unit q at the current moment, otherwise, the azimuth angle from the search remote radio unit q predicted in the step S5 to the helmet is taken as the azimuth angle of the search remote radio unit q at the current moment.
In the 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 an analog-to-digital converter, and the helmet selects the beam direction with the maximum intensity of the received signal by calculating the energy of the data obtained by sampling.
In said step S3, the optimal estimate of the helmet position is:
wherein
A t ＝A t-1 +ΔA(φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )
f 1 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 cos 2 φ q,t-1 -sin 2 θ q,t cos 2 φ q,t
f 2 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sinφ q,t-1 cosφ q,t-1 -sin 2 θ q,t sinφ q,t cosφ q,t
f 3 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 cosφ q,t-1 -sinθ q,t cosθ q,t cosφ q,t
f 4 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sin 2 φ q,t-1 -sin 2 θ q,t sin 2 φ q,t
f 5 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 sinφ q,t-1 -sinθ q,t cosθ q,t sinφ q,t
f 6 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t -sin 2 θ q,t-1
wherein ,φq,t ,θ q,t Represents the azimuth angle phi of the search remote radio unit q at the current time t q,t-1 ,θ q,t-1 Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x) q ,y q ,z q ) Representing the spatial coordinates of the search remote unit q, ΔA (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 ) Only the azimuth angles of the search remote radio unit q at the current time t and the last time t-1.
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 angle of the current working 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:
wherein ,
for the helmet position at the current time t, (x) p ,y p ,z p ) And the position coordinates of the current working remote radio unit p are obtained.
The fast tracking method of the wave beam azimuth in the wireless virtual reality system detects the position of the helmet by utilizing the search remote radio unit for detecting the obstacle, and the current working remote radio unit responsible for transmitting the high-definition video and the high-fidelity audio does not carry out wave beam scanning. Because the searching remote radio unit is not responsible for the transmission of audio and video information, the beam scanning can be carried out uninterruptedly, so that the highest beam scanning frequency is achieved, and the current working remote radio unit can also transmit data at high speed when a user moves.
In addition, the fast tracking method of the wave beam azimuth in the wireless virtual reality system leads the bandwidth of the channel detection signal to be the same as the bandwidths of the high-definition video and the high-fidelity audio signals after the channel detection signal is spread by spreading, so that the signals with two bandwidths do not need to be respectively adapted in the remote radio unit, thereby simplifying a hardware circuit; 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=100, the total transmit power of 8 remote units after spreading is only 13.4% of the total transmit power before spreading. Thereby significantly reducing the power consumption of the host.
In addition, the rapid tracking method of the beam azimuth in the wireless virtual reality system fully utilizes the information of the last moment to predict the azimuth, so that the searching range of the current moment t to the beam is reduced, the beam is not required to be searched in the whole space, and only the vicinity of the predicted position is searched, and the speed of the beam searching is increased.
Furthermore, since the fast tracking method of the wave beam azimuth in the wireless virtual reality system of the invention only updates the azimuth of one searching remote radio unit at one moment, the matrix A is calculated t Sum vector b t And in the time, incremental calculation can be adopted, so that the calculated 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 invention.
Detailed Description
The invention will be further illustrated with reference to specific examples. It should be understood that the following examples are illustrative of the present invention 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 characterized in that 1 host computer, 1 helmet R1 and 8 remote radio units R2 are installed in a room, the numbers of the host computer, the helmet R1 and the 8 remote radio units R2 are respectively 1,2, 8, and the space coordinates of the kth remote radio unit R2 are (x k ,y k ,z k ) And (3) representing. The host is a computer and is responsible for generating high-definition video and high-fidelity audio. And 1 radio remote unit R2 is selected from 8 radio remote units R2 to perform high-speed data transmission with the helmet R1, and the high-definition video and the high-fidelity audio generated by the host are transmitted to the helmet R1. The other 7 remote units R2 continuously transmit channel sounding signals for detecting the channel quality from each remote unit R2 to the helmet R1. Once the barrier appears before the remote radio unit R2 and the helmet R1 which are currently responsible for high-speed data transmission, the remote radio unit R2 is rapidly switched to the remote radio unit with the best channel quality in the rest 7 remote radio units R2 so as to ensure uninterrupted transmission of audio and video information.
The invention provides a fast tracking method of a wave beam azimuth angle 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 comprises a plurality of radio remote units R2, one radio remote unit R2 is responsible for transmitting high-definition video and high-fidelity audio without wave beam scanning, and is called as a current working radio remote unit, and the other 7 radio remote units R2 transmit channel detection signals to detect the position of a helmet R1, which is called as a searching radio remote unit. Since the searching remote radio unit R2 is not responsible for the transmission of audio and video information, the beam scanning can be continuously performed all the time, so that the highest beam scanning frequency is achieved, and the current working remote radio unit can also transmit data at high speed when a user moves.
The method for quickly tracking the azimuth angle of the wave beam in the wireless virtual reality system can be divided into two stages of initialization and quick tracking of the wave beam, and specifically comprises the following steps:
at the current time t=0, the initialization phase is defined.
Step S0: all remote units R2 are initialized to select the working remote unit p. Subsequently, an optimal estimate of the helmet position is initialized
And a construction matrix A thereof 0 Construction vector b 0 。
All remote radio units R2 are initialized, which specifically includes:
all remote units R2 are numbered 1, 2. Transmitting channel detection signals in all possible beam directions by using delta phi and delta theta as search steps in sequence by using all remote radio units R2 to perform exhaustive search, and selecting the beam direction with the maximum received signal strength as the azimuth angle of the remote radio units during initialization after the helmet R1 receives the channel detection signals, wherein the horizontal component of the azimuth angle uses phi k,0 Expressed as θ for vertical component k,0 And (3) representing. And selecting one remote radio unit R2 as a current working remote radio unit p, and respectively setting the rest numbers as 1 according to the increment of time, wherein the remote radio units R2 of p-1, p+1 and 8 are alternately used as a search remote radio unit q. The set of indices for all search remote units is denoted by Ω= {1, …, p-1, p+1,..8 }.
Considering that all the remote units are positioned at the top of the room, each remote unit only needs to search 1/4 plane, namely 90 degrees, in the horizontal direction; only the upper half space or the lower half space, i.e. 90 deg., has to be searched in the vertical direction.
Thus, during the initialization phase, each remote radio unit needs to search
Beam direction of>
As a round-up function.
The optimal estimate of the initialized helmet position is:
wherein the construction matrix A of the initialized helmet position estimate 0 Construction vector b 0 The method comprises the following steps of:
φ k,0 ,θ k,0 indicating the azimuth angle of the kth remote unit, (x) k ,y k ,z k ) Representing the space coordinates of a kth remote radio unit;
when the current time t is more than 0, the method is a beam tracking stage, and specifically comprises the following steps:
step S1: and transmitting channel detection signals in (2A+1) x (2B+1) beam directions to the helmet R1 by utilizing the current working remote radio unit p and the helmet R1 to perform high-speed transmission of high-definition video and high-fidelity audio signals, and simultaneously utilizing the current moment searching remote radio unit q to perform beam searching.
In said step S1, the horizontal component of the beam direction of the transmitted channel-sounding signal is
The vertical component is +.>
To search for the horizontal component of the azimuth of the remote radio unit q to the helmet R1, +.>
For searching the vertical component of the azimuth of the remote radio unit q to the helmet R1, ΔΦ, Δθ is the search step, ΔΦ, Δθ is typically 5 ° or 10 °, a, B is a positive integer, and a, B is typically 1,2 or 3.
Typically, the bandwidth of the channel sounding signal before spreading is much smaller than the bandwidth of the high definition video and high fidelity audio signals. Let the latter bandwidth be Q times the former bandwidth, where Q is an integer and the 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 fast tracking method of the wave beam azimuth in the wireless virtual reality system, before the channel detection signal is transmitted, the spreading operation is performed, the spreading sequence uses a Zadoff-Chu sequence, the length is Q, the roots of the Zadoff-Chu sequences used by different remote radio units are different, and the bandwidth of the channel detection signal after spreading is the same as the bandwidth of the high-definition video and high-fidelity audio signals. Thus, the invention only needs to use one shaping filter, and does not need a switch.
Therefore, the invention realizes two advantages by spreading the channel detection signal: the bandwidth of the channel detection signal after frequency expansion 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 a remote radio unit to respectively adapt to the signals with the two bandwidths, and a hardware circuit is simplified. Second, helmet R1 can accumulate energy over the entire spreading sequence when detecting the 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 transmit energy of the remote units may be 1/Q before spreading. Let the transmitting power of the remote radio unit be P RRU . If not spread, the total transmitting power of 8 RRU is 8P RRU . After spreading, the total transmitting power of 8 RRU is (1+7/Q) P RRU . If q=100, the total transmit power after spreading is only 13.4% of the total transmit power before spreading。
Step S2: after receiving the channel detection signal, the helmet R1 selects a wave beam with highest received signal intensity as an azimuth angle of the searching remote radio unit q at the current moment and feeds the azimuth angle back to the host.
The helmet R1 performs matching correlation on the received spread spectrum signals through a multiplier and an adder in an analog circuit, then samples the data after matching correlation by utilizing an analog-to-digital converter, and selects the beam direction with the maximum intensity of the received signals by calculating the energy of the data obtained by sampling. Wherein the horizontal component of the azimuth angle of the remote radio unit q at the current time t is phi q,t Expressed as θ for vertical component q,t And (3) representing.
In the step S2, when the current time t is greater than 0, whether an obstacle exists between the search remote radio unit q and the helmet R1 is determined according to the intensity of the received channel detection signal, if the intensity of the received channel detection signal is greater than a threshold value, no obstacle exists between the search remote radio unit q and the helmet R1, and then a beam with the highest intensity of the received signal is selected as the azimuth angle of the search remote radio unit q at the current time. On the contrary, if there is an obstacle between the search remote unit q and the helmet R1, the signal of the beam with the highest received signal strength may be weak, in which case the signal is directly transmitted
And taking the azimuth angle of the searching radio remote unit q predicted in the step S5 to the helmet R1 as the azimuth angle of the searching radio remote unit q at the current moment.
The invention carries out matching correlation on the received spread spectrum signal in the analog circuit through the helmet, and solves the problem that the power consumption of the analog-to-digital converter for the broadband signal is higher than that of the analog-to-digital converter for the narrowband signal for the helmet. This is because the matching 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 correlation. The symbol rate of the data has now fallen to exactly the same as the non-spread signal and thus the power consumption of the analog-to-digital converter is also the same as the non-spread signal.
Step S3: updating the optimal estimation of the helmet position at the current moment;
wherein in said step S3 an optimal estimate of the helmet position at the current moment t is obtained
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 azimuth is inevitably subject to errors, so more lines are required to reduce the estimation errors.
Order the
Indicating the position of the helmet at time t, d k Indicating the distance of the helmet from the line in which the beam of the kth remote radio unit is located. Then
The sum of the distances from the helmet R1 to all straight lines is
If there is no measurement error, d 2 =0. In the case of measurement errors, in order to obtain an optimal estimate of the helmet R1 position, the above derivative is derived,
order the
The following equation can be obtained
wherein
Therefore, an optimal estimation of the helmet position
The method comprises the following steps:
except for the remote units q, the rest of the remote units do not update the estimate of azimuth at time t, i.e. have phi k,t ＝φ k,t-1 ,
and θk,t ＝θ k,t-1 ,/>
Therefore, in order to reduce the calculation amount, A t and bt Can be written in the following form
A t ＝A t-1 +ΔA(φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )
Wherein, deltaA (phi) q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 ) Only in relation to the azimuth of the search for the remote unit q at times t and t-1,
f 1 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 cos 2 φ q,t-1 -sin 2 θ q,t cos 2 φ q,t
f 2 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sinφ q,t-1 cosφ q,t-1 -sin 2 θ q,t sinφ q,t cosφ q,t
f 3 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 cosφ q,t-1 -sinθ q,t cosθ q,t cosφ q,t
f 4 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sin 2 φ q,t-1 -sin 2 θ q,t sin 2 φ q,t
f 5 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 sinφ q,t-1 -sinθ q,t cosθ q,t sinφ q,t
f 6 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t -sin 2 θ q,t-1
wherein ,φq,t ,θ q,t Represents the azimuth angle phi of the search remote radio unit q at the current time t q,t-1 ,θ q,t-1 Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x) q ,y q ,z q ) Representing the spatial coordinates of the search remote unit q.
Step S4: according to the optimal estimation in the step S3
The azimuth angle of the current working remote radio unit p is adjusted;
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 angle of the current working 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:
wherein ,
for the helmet position at the current time t, (x) p ,y p ,z p ) And the position coordinates of the current working remote radio unit p are obtained.
Then, another search remote unit becomes the search remote unit q at the current time, thereby updating the search remote unit q at the current time.
Step S5: when the value of the current time t is increased, updating the searching remote radio unit q of the current time, and according to the space coordinates of the searching remote radio unit q and the optimal estimation in the step S3 (the optimal estimation is used as the helmet position of the last time t-1)
) And predicting the azimuth angle from the searching radio remote unit q at the new current moment to the helmet R1.
The position of helmet R1 may change from time t-1 to time t, so that remote radio unit q needs to transmit beams, i.e. beam scans, in a plurality of adjacent directions, respectively. Since the position of the helmet R1 does not change drastically at the two moments, the beam direction emitted at the moment t is searched for a small range in the vicinity thereof with reference to the position at the moment t-1. Thus, from the estimate of the helmet R1 position at time t-1, the azimuth angle of the outgoing remote unit q to the helmet R1 can be predicted.
The azimuth angle from the searching radio remote unit q to the helmet is predicted according to the helmet position at the last time t-1, and the horizontal component of the azimuth angle from the searching radio remote unit q to the helmet R1 is as follows:
the vertical component of the azimuth angle from the search remote radio unit q to the helmet R1 is as follows:
wherein ,
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 ,y q ,z q ) Space sitting for searching remote radio unit qAnd (5) marking.
Step S6: and (4) searching the vicinity of the azimuth angle from the remote radio unit q to the helmet R1 in the step S5, and repeating the steps S1-S4.
Step S7: repeating the steps S5-S6.
The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and various modifications can be made to the above-described embodiment of the present invention. All simple, equivalent changes and modifications made in accordance with the claims and the specification of the present application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.
Claims (6)
1. A method for fast tracking of 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 is characterized by comprising the following steps:
step S0: selecting a current working remote radio unit p, and using the rest remote radio units 1, p-1, p+1, 8 as search remote radio units q in turn along with the increment of time, then setting the current time t to 0, and initializing the optimal estimation of the helmet position
And a construction matrix A thereof 0 Construction vector b 0 Then increasing t to 1;
step S1: transmitting high-definition video and high-fidelity audio signals by using the current working remote radio unit p and the helmet, and transmitting channel detection signals in (2A+1) x (2B+1) beam directions to the helmet by using the current time searching remote radio unit q, wherein A and B are positive integers;
step S2: after receiving the channel detection signal, the helmet acquires the azimuth angle of the searching remote radio unit q at the current moment and feeds the azimuth angle back 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 current working remote radio unit p according to the optimal estimation in the step S3;
step S5: updating the searching radio remote unit q at the current moment when the value of the current moment t is increased, and predicting the azimuth angle from the searching radio remote unit q at the current moment to the helmet according to the space coordinate of the searching radio remote unit q and the optimal estimation in the step S3;
step S6: carrying out beam searching again in the vicinity of the azimuth angle from the searching radio remote unit q to the helmet in the step S5, and repeating the steps S1-S4;
step S7: repeating the steps S5-S6;
in the step S3, the optimal estimation of the helmet position is:
wherein
A t ＝A t-1 +ΔA(φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )
f 1 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 cos 2 φ q,t-1 -sin 2 θ q,t cos 2 φ q,t
f 2 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sinφ q,t-1 cosφ q,t-1 -sin 2 θ q,t sinφ q,t cosφ q,t
f 3 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 cosφ q,t-1 -sinθ q,t cosθ q,t cosφ q,t
f 4 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t-1 sin 2 φ q,t-1 -sin 2 θ q,t sin 2 φ q,t
f 5 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sinθ q,t-1 cosθ q,t-1 sinφ q,t-1 -sinθ q,t cosθ q,t sinφ q,t
f 6 (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 )＝sin 2 θ q,t -sin 2 θ q,t-1
wherein ,φq,t ,θ q,t Represents the azimuth angle phi of the search remote radio unit q at the current time t q,t-1 ,θ q,t-1 Represents the azimuth angle of the searching remote radio unit q at the last time t-1, (x) q ,y q ,z q ) Representing the spatial coordinates of the search remote unit q, ΔA (φ q,t ,θ q,t ,φ q,t-1 ,θ q,t-1 ) Only the azimuth angles of the search remote radio unit q at the current time t and the last time t-1.
2. The method according to claim 1, wherein in said step S1, the horizontal component of the beam direction of the transmitted channel sounding signal is
The vertical component is +.>
To search for the horizontal component of the azimuth of the remote unit q to the helmet, < >>
To search for the vertical component of the azimuth of the remote unit q to the helmet, delta phi, delta theta is the search step,
and in the step S5, the azimuth angle from the search remote radio unit q to the helmet is predicted according to the helmet position at the previous 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 as follows:
the calculation formula for searching the vertical component of the azimuth angle from the remote radio unit q to the helmet is as follows:
wherein ,
the helmet position at the last time t-1, (x) q ,y q ,z q ) To search for the spatial coordinates of the remote radio unit q.
3. The method according to claim 1, wherein in the step S1, a spreading operation is performed before the channel sounding signal is transmitted, the spreading sequences use Zadoff-Chu sequences, the roots of the Zadoff-Chu sequences used by different remote radio units are different from each other, and after the spreading, the bandwidth of the channel sounding signal is the same as the bandwidths of the high definition video and high fidelity audio signals.
4. The method according to claim 1, wherein in the step S2, it is determined whether an obstacle exists between the search remote unit q and the helmet according to the intensity of the received channel detection signal, if the intensity of the received channel detection signal is greater than a threshold, no obstacle exists between the search remote unit q and the helmet, a beam with the highest intensity of the received signal is selected as the azimuth angle of the search remote unit q at the current moment, otherwise, the azimuth angle from the search remote unit q predicted in the step S5 to the helmet is taken as the azimuth angle of the search remote unit q at the current moment.
5. The method according to claim 4, wherein in the step S2, the helmet performs matching correlation on the received spread spectrum signal through a multiplier and an adder in an analog circuit, and then samples the data after matching correlation by using an analog-to-digital converter, and the helmet selects the beam direction with the maximum intensity of the received signal by calculating the energy of the data obtained by sampling.
6. The method according to claim 1, wherein in the step S4, the optimal estimation of the helmet position in the step S3 is used as the helmet position at the current time t, and the azimuth angle of the current working 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:
wherein ,
for the helmet position at the current time t, (x) p ,y p ,z p ) And the position coordinates of the current working remote radio unit p are obtained. />
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