CN114095861A - Timing adjustment mechanism for signal transmission in non-terrestrial networks - Google Patents
Timing adjustment mechanism for signal transmission in non-terrestrial networks Download PDFInfo
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1851—Systems using a satellite or space-based relay
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
- H04W4/02—Services making use of location information
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1853—Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
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- H04W28/0231—Traffic management, e.g. flow control or congestion control based on communication conditions
- H04W28/0236—Traffic management, e.g. flow control or congestion control based on communication conditions radio quality, e.g. interference, losses or delay
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- H—ELECTRICITY
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
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- H—ELECTRICITY
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W84/00—Network topologies
- H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
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Abstract
The invention provides a timing sequence adjusting method. The time sequence adjusting method comprises the following steps: obtaining a predetermined initial timing of signal transmission from a user equipment to a satellite through a gateway in a non-terrestrial network; and in response to the number of failures in the signal transmission being greater than or equal to a first predetermined number, shifting, with the user equipment, timing for a subsequent signal transmission using a timing adjustment mechanism.
Description
Technical Field
The present invention generally relates to wireless communications. In particular, the present invention relates to a signal transmission timing adjustment mechanism for Non-Terrestrial Network (NTN).
Background
A non-Terrestrial Network (NTN) system may provide communication services, such as oceans, deserts, mountainous areas, high altitudes, and the like, in areas without Terrestrial Network (TN) services. In addition, the NTN communication can also be used as a backup scheme of the TN. When TN traffic is unavailable for some reason, the terminal may attempt to communicate through the NTN. NTN communication and TN communication have different physical characteristics in terms of time delay.
Since the communication distance between the user terminal and the satellite varies with the movement of the satellite, the signal delay (signal delay) of the NTN is large and time-varying with respect to the TN communication system. Taking a Geostationary Earth Orbit (GEO) satellite with an altitude of 35778 km as an example, assume that the base station is on the ground and the GEO satellite has an elevation angle relative to the base station gateway and the user terminal of about 10 degrees above the horizon. Fig. 1 shows the Round-Trip Propagation Delay (RTD) of a GEO satellite at 35778 km height. For example, as shown in fig. 1, the round trip propagation delay (i.e., RTD) from the user terminal to the GEO satellite to the gateway may drift between 535.4 milliseconds (ms) to 514.4 ms in one day (24 hours) with a maximum drift rate of ± 0.25 microseconds/second.
Figure 2 shows the round trip propagation delay of a LEO satellite at a height of 600 km. Taking a LEO satellite with an altitude of 600 km as an example, assuming that the base station is on the ground (e.g., sea level), when the user terminal enters the LEO satellite coverage area at an elevation angle of 10 degrees, as shown in fig. 2, the round trip propagation delay from the user terminal to the LEO satellite to the base station gateway drifts between 10 milliseconds and 26 milliseconds as the LEO satellite moves within the LEO satellite coverage area, wherein the maximum drift rate is ± 80 microseconds/second.
Fig. 3 illustrates the common and residual propagation delays for LEO satellite 310, assuming a beam layout based on a 3dB coverage angle (theta)3dB). To more efficiently use radio resources and to more efficiently integrate the NTN and TN, the NTN system may divide the propagation delay intoIs in two parts. The propagation delay of the reference point 320 is set to the common propagation delay with the position of the satellite 310 closest to the terminal in the cell 0 as the reference point 320. As shown in fig. 3, the propagation delays of other cell positions can be divided into a common propagation delay (common propagation delay) and a residual propagation delay (residual propagation delay).
Thus, common propagation delays in the beams can be compensated by the satellite or user terminal, and the remaining propagation delays are supported by the communication system design.
Disclosure of Invention
In an exemplary embodiment, a method is provided. The method comprises the following steps: acquiring a predetermined initial timing of signal transmission from a User Equipment (UE) to a satellite through a gateway in a non-terrestrial network; in response to the number of failures in the signal transmission being greater than or equal to a first predetermined number, shifting, with the UE, timing for a subsequent signal transmission using a timing adjustment mechanism.
In some embodiments, when the UE cannot acquire sign bit (sign bit) information of the propagation delay drift rate from the UE to the satellite through the gateway, the UE performs a timing adjustment mechanism to offset the timing of each round of signal transmission, wherein the timing adjustment mechanism uses a positive and negative alternating sequence. S (n) for positive and negative alternate sequence2) Δ t, and function S (n)2) Expressed as:
wherein Δ t represents a minimum time shift unit defined in a transmission protocol used by the UE; function S (n)2) Represents an adjustment step per offset; n is2Is an integer between 0 and a second predetermined number.
In some embodiments, the transmission power for subsequent signal transmissions is adjusted with the UE in response to the number of signal transmission failures being less than a first predetermined number. In response to the number of signal transmission failures being greater than or equal to a predetermined parameter, the UE determines that the transmission between the UE and the satellite was not successfully established.
The embodiment of the invention provides a method. The method comprises the following steps: performing, with a User Equipment (UE), the steps of: estimating drift rate and sign bit of propagation delay from UE to satellite through a base station gateway in a non-ground network; a timing adjustment mechanism is implemented to adjust the timing of signal transmission from the UE to the satellite through the gateway using the estimated drift rate and its sign bit.
In some embodiments, the step of estimating the drift rate of the propagation delay from the UE to the satellite through the base station gateway and its sign bit in the non-terrestrial network comprises: acquiring ephemeris data (ephemeris data) of satellites in a non-terrestrial network; acquiring position information of a base station gateway in a non-ground network; calculating the position and track information of the satellite by using the acquired ephemeris data; acquiring position information of the UE from a GNSS sensor arranged in the UE; calculating a propagation delay by dividing a relative distance between the UE and the satellite through the gateway by the speed of light; and estimating the drift rate of the propagation delay and the sign bit thereof according to the calculated satellite trajectory information.
In some embodiments, the step of estimating the drift rate of the propagation delay from the UE to the satellite through the base station gateway and its sign bit in the non-terrestrial network comprises: performing, with the UE, the steps of: performing an estimation algorithm to estimate a timing offset of a downlink channel from the satellite to the UE; estimating a drift rate of the downlink channel and a sign bit thereof using the estimated timing offset of the downlink channel; and setting the drift rate and the sign bit of the downlink channel as the drift rate and the sign bit of the uplink channel from the UE to the satellite.
In some embodiments, the step of estimating the drift rate of the propagation delay from the UE to the satellite through the base station gateway and its sign bits in the non-terrestrial network comprises performing, with the UE, the steps of: acquiring northern hemisphere or southern hemisphere information of a UE from a Global Navigation Satellite System (GNSS) sensor provided in the UE; obtaining the information of a northern hemisphere or a southern hemisphere of the gateway; acquiring latitude information of a satellite; and predicting the drift rate and the sign bit of the propagation delay by using the acquired northern hemisphere or southern hemisphere information of the UE, the northern hemisphere or southern hemisphere information of the gateway and the latitude information of the satellite.
In some embodiments, the step of estimating the drift rate of the propagation delay from the UE to the satellite through the base station gateway and its sign bits in the non-terrestrial network comprises the steps of, with the UE: the drift rate of the propagation delay of the satellite is acquired through broadcasting system information or the internet.
In another exemplary embodiment, an apparatus is provided. The device includes: a processing circuit configured to: obtaining a predetermined initial timing for signal transmission from a device to a satellite through a gateway in a non-terrestrial network; and in response to the number of signal transmission failures being greater than or equal to a first predetermined number, shifting a timing for a subsequent signal transmission using a timing adjustment mechanism.
In some embodiments, when the processing circuitry is unable to obtain sign bit information of the propagation delay drift rate from the device to the satellite through the gateway, the processing circuitry uses a timing adjustment mechanism to offset the timing of each round of signal transmission, wherein a positive and negative alternating step sequence is used. S (n) for positive and negative alternate sequence2) Δ t, and function S (n)2) Expressed as:
wherein Δ t represents a minimum time shift unit defined in a transmission protocol used by the UE; function S (n)2) Represents an adjustment step per offset; n is2Is an integer between 0 and a second predetermined number.
In some embodiments, the processing circuit adjusts the transmission power for subsequent signal transmissions in response to the number of signal transmission failures being less than a first predetermined number. In response to the number of failures in signal transmission being greater than or equal to a predetermined parameter, the processing circuitry determines that the transmission between the UE and the satellite was not successfully established.
In yet another exemplary embodiment, an apparatus is provided. The apparatus comprises processing circuitry configured to: estimating drift rate and sign bit of propagation delay from the device to the satellite through a base station gateway in the non-terrestrial network; a timing adjustment mechanism is implemented to adjust the timing of signal transmission from the device to the satellite through the gateway using the estimated drift rate and its sign bit.
In some embodiments, the processing circuitry is further to: acquiring ephemeris data of a satellite in a non-terrestrial network; acquiring position information of a base station gateway in a non-ground network; calculating the position and track information of the satellite by using the acquired ephemeris data; acquiring position information of a device from a GNSS sensor provided in the device; calculating a propagation delay by dividing a relative distance between a device passing through the gateway and the satellite by the speed of light; and estimating the drift rate of the propagation delay and the sign bit thereof according to the calculated satellite trajectory information.
In some embodiments, the processing circuitry is further configured to: performing an estimation algorithm to estimate a timing offset of a downlink channel from the satellite to the device; estimating a drift rate of a downlink channel and a sign bit thereof using the estimated downlink channel timing offset; the drift rate of the downlink channel and its sign bit are set to the drift rate of the uplink channel from the device to the satellite and its sign bit.
In some embodiments, the processing circuitry is further configured to: acquiring information of a northern hemisphere or a southern hemisphere of the device from a GNSS sensor provided in the apparatus; obtaining the information of a northern hemisphere or a southern hemisphere of the gateway; acquiring latitude information of a satellite; and predicting the drift rate and the sign bit of the propagation delay by using the acquired northern hemisphere or southern hemisphere information of the device, the northern hemisphere or southern hemisphere information of the gateway and the latitude information of the satellite.
In some embodiments, the processing circuitry is further to: the drift rate of the propagation delay of the satellite is acquired through broadcasting system information or the internet.
Drawings
The following figures depict embodiments of the present invention in which like numerals represent like elements.
Figure 1 shows the round trip propagation delay of a GEO satellite at 35778 km height.
Figure 2 shows the round trip propagation delay of a LEO satellite at a height of 600 km.
Fig. 3 shows the common propagation delay and the residual propagation delay of LEO satellite 310.
Fig. 4 is a schematic diagram of a non-terrestrial network (NTN) system according to an embodiment of the present invention.
FIG. 5 is a sequence diagram illustrating steps used in a timing adjustment mechanism according to an embodiment of the present invention.
FIG. 6 is a sequence diagram illustrating steps used in a timing adjustment mechanism according to another embodiment of the present invention.
FIG. 7 is a sequence diagram illustrating steps used in a timing adjustment mechanism according to another embodiment of the present invention.
FIG. 8 is a flowchart illustrating a sequence of steps used in a timing adjustment mechanism according to another embodiment of the present invention.
Fig. 9 is a flowchart of a timing adjustment method in a non-terrestrial network (NTN) according to an embodiment of the present invention.
Fig. 10 is a flowchart of a timing adjustment method in a non-terrestrial network (NTN) according to another embodiment of the present invention.
Detailed Description
Certain terms are used throughout the description and following claims to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. Furthermore, the term "coupled" is intended to encompass any direct or indirect electrical connection. Thus, if a first device couples to a second device, that connection may be through a direct electrical connection, or through an indirect electrical connection via other devices and connections.
The following description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
The following description is presented to enable one of ordinary skill in the art to make and use the invention and is provided in the context of a patent application and its requirements. Various modifications to the embodiments and the generic principles and features described herein will be readily apparent to those skilled in the art. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features described herein.
Fig. 4 is a schematic diagram of a non-terrestrial network (NTN) system according to an embodiment of the present invention.
For ease of description, as shown in fig. 4, the NTN system 400 may include a satellite 410, a base station 420, a gateway 425, and a User Equipment (UE) 430. In some embodiments, NTN system 400 may include one or more satellites 410, one or more base stations 420, and one or more devices of UE 430. The satellite 410 has a satellite orbital altitude 440 (e.g., GEO satellite or LEO satellite) that depends on the type of satellite 410. The coverage area of the satellite 410 has a radius 450. In some embodiments, the base station 420 may be considered an "evolved node B" (i.e., abbreviated "eNB") if Long Term Evolution (LTE) protocols are used. The UE430 may be a mobile electronic device such as a smart phone, a tablet computer, etc., but the invention is not limited thereto. In some embodiments, the UE430 may include a GNSS sensor or a Global Positioning System (GPS) sensor capable of receiving positioning information from one or more satellites, and the UE430 may determine its own location information using the received positioning information.
In some embodiments, base station 420, gateway 425, and UE430 may be within a terrestrial network cell 460. The gateway 425 may be located between a wired network (e.g., the internet) and a wireless network (e.g., the NTN or TN). Further, multiple base stations 420 may be connected to the gateway 425, and the gateway 425 and the base stations 420 may be located in different locations, where the gateway 425 is capable of communicating with the satellite 410 and the UE 430. In other embodiments, the gateway 425 may be located in the satellite 410, which allows the UE430 to communicate directly with the satellite 410.
Communications between the satellite 410 and the gateway 425 or the user terminal 430 may be considered communications in a non-terrestrial network (NTN), and communications between the gateway 425 and the user terminal 430 may be considered communications in a Terrestrial Network (TN). The following embodiment will be described next with reference to fig. 4.
Example 0: predetermined timing
Scene 0-1:
in one embodiment, the UE430 may use the location information of the UE430, the satellite 410, and the gateway 425 to perform accurate initial propagation delay pre-compensation. For example, the UE430 may calculate position and trajectory information for the satellites 410 using ephemeris data for the satellites 410, where the UE430 may obtain the ephemeris data from a broadcast of the satellites 410 or from the internet. Further, the UE430 may obtain its own location information using a GNSS sensor disposed in the UE430 and obtain location information of the base station 420 using system information or from the internet.
Thus, the UE430 can very accurately calculate and pre-compensate for the initial propagation delay of the round trip route from the UE430 to the satellite 410 and the gateway 425 using the speed of light and the locations of the UE430, the satellite 410, and the base station 420. For example, the initial propagation delay may be calculated by dividing the total distance of the above round trip routes by the speed of light. Thereafter, the timing adjustment mechanism performed by the UE430 may calculate the remaining propagation delay using a propagation delay drift scheme.
Scenes 0-2:
in one embodiment, the UE430 may perform coarse initial propagation delay pre-compensation by a fixed value for each beam. Thereafter, the timing adjustment mechanism performed by the UE430 may calculate the remaining propagation delay using the pre-compensation error and the propagation delay drift scheme.
Example 1: detecting failure events
Scene 1-1:
in one embodiment, UE430 may determine that the signal transmission failed if UE430 did not receive any Random Access Response (RAR) from satellite 410 within a predetermined random access response window or if the random access response received after UE430 sent a signal to gateway 425 (or satellite 410) does not contain the transmitted preamble. Here, if the LTE protocol is used between the UE430 and the base station 420 (or the gateway 425), the signal may be in a Physical Random Access Channel (PRACH), a Physical Uplink Shared Channel (PUSCH), a Physical Uplink Control Channel (PUCCH), or the like, but the present invention is not limited thereto. It should be noted that the above-mentioned signals may be any other signals if a different protocol is used between the UE430 and the base station 420 (or gateway 425).
If the UE430 determines that the current signal transmission fails, the UE430 may increase the value of the preamble transmission counter by 1. When the UE430 determines that the signal transmission failed N1 times consecutively (i.e., the preamble transmission counter equals N1), the UE430 may initiate a timing adjustment mechanism to correct the transmission timing. For example, if the LTE protocol is used between the UE430 and the base station 420, the maximum number of transmissions, i.e., preambleTransMax, is defined in the preamble of the signal. If the UE430 determines that the signal transmission failed, the UE430 may adjust the transmission power for the next signal transmission. If the number of signal transmissions exceeds the parameter preambleTransMax, the UE430 may determine that the transmission power meets the requirements and may indicate a random access procedure (RACH) problem to the upper layers. In this embodiment, the value N1 is equal to the parameter preamblltransmax.
Scenes 1-2:
in another embodiment, the UE430 may initiate the timing adjustment mechanism after the first round of signal transmission fails. For example, when the UE430 performs a round of timing adjustment mechanism, the UE430 may obtain the adjusted timing and adjusted power for the next signal transmission. That is, a timing adjustment mechanism may be implemented to calibrate timing errors and retransmit signals to ensure reliability of signal transmission. Taking the preamble transmission in the LTE system as an example, the value of N3 may be the maximum number of rounds of the timing adjustment mechanism. In this case, N3 may be equal to the parameter preamblltransmax, and N1 ═ 1 (i.e., N3 and N1 are positive integers). To achieve signal timing alignment between the base station 420 and the UE430 as quickly as possible, maximum power may be used in the first round of signal transmission.
Scenes 1-3:
in yet another embodiment, the values N3 and N1 described in scenarios 1-2 may be a random combination that satisfies the following equation:
N1+N3＝preambleTransMax.
example 2: timing adjustment mechanism
For convenience of description, it is assumed that a time-shift value (timing-shift value) may be S (n)2) Δ t, where Δ t represents the minimumTime shift units of (e.g., may be a few microseconds); n is2Represents the number of time shift wheels; function S (n)2) Indicating the adjustment step size for each offset.
Scene 2-1:
in one embodiment, the UE430 cannot obtain sign bit information of the drift rate of the propagation delay. Since the propagation delay at the base station 420 (i.e., eNB) may drift in the negative and positive directions, as shown in the upper part of fig. 5, the timing adjustment mechanism performed by the UE430 may arrange the transmission timing as a positive and negative alternating sequence, represented by equation (2):
wherein n is2Is an integer from 0 to N2. In this case, Δ t ═ CPlenWherein CPlen(i.e., cyclic prefix length) represents the maximum tolerable timing error range for normal signal transmission. For example, in the first round of signal transmission (i.e., n)21), function S (n)2) Equal to 0 and the UE430 may use a predetermined initial timing TinitThe propagation delay is compensated in advance. In the second round of signal transmission (i.e. n)22), function S (n)2) Equal to 1, the UE430 may use Tinit+CPlenThe propagation delay is compensated in advance. In the third round of signal transmission (i.e. n)23), function S (n)2) Equal to-1, the UE430 may use Tinit-CPlenAnd the propagation delay is compensated in advance, and so on. The UE430 will continue to perform the timing adjustment mechanism until the base station 420 (or satellite 410) successfully detects the transmitted signal. Scene 2-2:
in another embodiment, the UE430 cannot obtain the sign bit information of the drift rate of the propagation delay, but the UE430 has pre-compensated the initial propagation delay with sufficient accuracy. Thus, the UE430 may perform subsequent signal transmissions based on the predetermined timing of the previous successful signal transmission. For example, in preamble transmission in a conventional TN system, the propagation delay of a transmission signal is always positive. However, in NTN systems, negative drift in propagation delay may occur. In this case, the UE430 may perform the timing adjustment mechanism using equation (3):
wherein n is2Is an integer from 0 to N2. In this case, it is preferable that the air conditioner,
wherein CPlenRepresenting the maximum tolerable timing error range for normal signal transmission. For example, in the first round of the timing adjustment mechanism (i.e., n)21), the UE430 may use Tinit+CPlenThe propagation delay is pre-compensated by/2 to allow for tolerance of small positive and negative drift propagation delays. In the second round of the timing adjustment mechanism (i.e., n)22), the UE430 may use TinitThe propagation delay is pre-compensated. In the third case of the timing adjustment mechanism (i.e., n)23), the UE430 may use Tinit+CPlenTo pre-compensate for propagation delay, etc.
In particular, because of the offset CP len2 is a better option to allow positive and negative drift of the tolerable small propagation delay at the beginning, so UE430 will use T when first trying to signal transmissioninit+CPlenAnd/2 to pre-compensate for propagation delay. Thus, there is a high probability that the first attempt will be successful without requiring a subsequent retry of the signal transmission.
Scene 2-3:
in yet another embodiment, it is assumed that the UE430 can obtain sign bit information of the drift rate of the propagation delay, and the sign bit is negative. In this case, this indicates that the propagation delay may drift in a negative direction, as shown in the upper half of fig. 7. Thus, as shown in the lower half of fig. 7, the UE430 can set the function S (n) by setting the function S2)＝n2To perform a timing adjustment mechanism using an incremental step sequence, where n2Is an integer of 0 to N2, and Δ t ═ CPlen。
Scenes 2-4:
in yet another aspectIn one embodiment, it is assumed that the UE430 can obtain sign bit information of the drift rate of the propagation delay, and the sign bit is positive. In this case, it is shown that the propagation delay may drift in a positive direction and may become larger and larger, as shown in the upper half of fig. 8. Thus, the UE430 may set the function S (n)2)＝-n2To perform the timing adjustment mechanism using a decreasing sequence of step sizes, as shown in the lower half of fig. 8, where n is2Is an integer of 0 to N2, and Δ t ═ CPlen。
Example 3: setting a maximum number of time shifts
Scene 3-1:
in one embodiment, the value N2 may be the maximum number of time shifts. Assume that the UE430 can obtain the maximum drift rate d _ rate for the propagation delay of the satellite 410 from broadcast system information (e.g., from a monitoring station that collects the ephemeris for various satellites) or from the InternetmaxThe information of (1). In addition, the UE430 may also obtain updated location information Period from broadcast system information or the internetlocationThe period of (c). As described in scenarios 2-1 and 2-2, if the propagation delay drifts in both the negative and positive directions, the UE430 may set
If the propagation delay drifts in one direction as described in scenarios 2-3 and 2-4, the UE430 may set
In one example, satellite 410 may be a LEO satellite with an altitude of 600 kilometers and use narrowband internet of things (NB-IoT) technology. As shown in fig. 2, the maximum drift rate d _ ratemaxIs 80 microseconds/second. Assume the CP Length in NB-IoT preamble Format 1 (i.e., CP)len) For the duration of the 266 microsecond range,
microsecond, if periodic Period of location information is updatedlocation2.5 seconds, UE430 may calculate N24. In addition, different cells may have different maximum times of time shifts.
Scene 3-2:
in another embodiment, it is assumed that the UE430 can obtain information about the precise drift rate d _ rate of the propagation delay of the satellite 410 from broadcast system information or from the internet. In addition, the UE430 may also obtain updated location information Period from broadcast system information or the internetlocationThe period of (c). As described in scenarios 2-1 and 2-2, if the propagation delay drifts in both the negative and positive directions, the UE430 may set
If the propagation delay drifts in one direction as described in scenarios 2-3 and 2-4, the UE430 may set
Example 4: obtaining drift rate of propagation delay
Scene 4-1:
in one embodiment, UE430 may use the precise location information of UE430, satellite 410, and gateway 425 to estimate the drift rate of the propagation delay. For example, the UE430 may obtain ephemeris data for the satellites 410 from broadcast system information or from the internet, and the UE430 may calculate position and trajectory information of the satellites using the obtained ephemeris data. In addition, the UE430 may obtain its own location information from a GNSS provided in the UE430 and obtain location information of the gateway 425 from broadcast system information or from the internet.
Specifically, the broadcast ephemeris data, which is continuously transmitted by the satellite 410 (or monitoring station), contains information about the satellite's orbit and the time of validity of the orbit information. Thus, the UE430 may calculate the orbits of the satellites 410 using the ephemeris data of the satellites 410 and predict the accurate position of the satellites 410 at a given time. Further, UE430 may calculate the propagation delay by dividing the relative distance between UE430 and satellite 410 through gateway 425 by the speed of light. The UE430 may also calculate a drift rate of the propagation delay and a sign bit thereof using the calculated trajectory information of the satellite 410.
Scene 4-2:
in another embodiment, the UE430 may estimate the drift rate of the propagation delay and its sign bit by performing an estimation algorithm of the downlink timing offset. For example, since the downlink channel and the uplink channel between the UE430 and the satellite 410 are opposite, the UE430 may use the drift rate of the propagation delay in the downlink channel as the propagation delay drift rate in the uplink channel.
For example, the estimation algorithm for the downlink timing offset may be implemented by a kalman filter, which is a recursive estimator that analyzes the signal and/or the time series to estimate the system state and remove any measurement errors and/or distortions that may be present.
Scene 4-3:
in yet another embodiment, the UE430 may predict a drift curve of the propagation delay based on the coarse latitude information of the UE430 and the gateway 425, and obtain a drift rate of the timing drift over time and sign bits thereof, and a drift curve of the propagation delay of the satellite 410. For example, the UE430 may obtain northern hemisphere or southern hemisphere information of the UE430 from a GNSS sensor provided in the UE430 or from fixed information. In addition, UE430 may obtain the northern hemisphere or southern hemisphere information of gateway 425 from broadcast system information, the internet, or fixed information. The UE430 may also obtain latitude information of the satellite 410 from broadcast system information, from the internet, or from fixed information. In an example, if satellite 410 is a GEO satellite with an altitude of 35778 kilometers, UE430 may use the aforementioned information to calculate the drift rate of the propagation delay over time and its sign bit. For example, as shown in fig. 1, the drift rate of the propagation delay is negative in the first half day, and the drift rate of the propagation delay is positive in the second half day.
Scene 4-4:
in yet another embodiment, scenario 4-4 is similar to scenario 4-3, except that the UE430 in scenario 4-4 may obtain the drift rate of the propagation delay of the satellite 410 from the broadcast system information or the Internet.
Fig. 9 is a flowchart of a timing adjustment method in a non-terrestrial network (NTN) according to an embodiment of the present invention. Please refer to fig. 4 and fig. 9.
In step S902, the UE430 performs initial propagation delay pre-compensation. For example, when the UE430 starts to perform initial propagation delay pre-compensation, the UE430 may set variables n, n1, n2, and n3 to initial values 0, where the variables n, n1, n2, and n3 are natural numbers.
In steps S904, S906, and S908, the UE430 sets variables n3, n2, and n1 to 0, respectively.
In step S910, the UE430 performs signal transmission to the satellite 410 through the gateway 425 and adds 1 to the variables n and nl. For example, the variable n may represent the number of signal transmissions that have been performed. The UE 430.
In step S912, the UE430 determines whether the signal transmission is successful. If the signal transmission is successful, step S930 is executed to indicate that the signal transmission is successful. Thus, the power sum configuration of successful signal transmissions may be used by the UE430 for subsequent signal transmissions. For example, if UE430 does not receive any Random Access Response (RAR) from satellite 410 within a predetermined Random Access Response (RAR) window or the received random access response does not contain the transmitted preamble after UE430 sends a signal to gateway 425 (or base station 420), UE430 may determine that the signal transmission failed. Here, if the LTE protocol is used between the UE430 and the base station 420 (or the gateway 425), the above signal may be on PRACH, PUSCH, PUCCH, or the like, but the present invention is not limited thereto. It should be noted that the above-mentioned signals may be any other signals if a different protocol is used between the UE430 and the base station 420 (or gateway 425).
In step S914, the UE430 determines whether the number of signal transmissions performed is below a predetermined parameter TransMax. If the number of signal transmissions is lower than the predetermined parameter TransMax, step S916 is executed. If the number of signal transmissions performed is not less than the predetermined parameter TransMax, step S932 is performed to indicate that the transmission from the UE430 to the satellite 410 cannot be successfully established.
In step S916, the UE430 determines whether the variable nl is less than a first predetermined number N1. If the judgment variable N1 is smaller than the first predetermined number N1, the flow returns to step S910. If the variable N1 is not less than the first predetermined number N1, step S918 is executed.
In step S918, the UE430 performs a timing adjustment mechanism to use S (n)2) The sequence of steps by Δ t shifts the timing of the signal transmission and increments variable n2 by 1. For example, Δ t represents the minimum time shift unit (e.g., which may be a few microseconds) defined in the transmission protocol (e.g., LTE) used in UE 430; function S (n)2) Indicating the adjustment step size for each offset.
In step S920, the UE430 determines whether the variable N2 is less than a second predetermined number N2. If the judgment variable N2 is smaller than the second predetermined number N2, the flow returns to step S908. If the variable N2 is not less than the second predetermined number N2, step S922 is executed to add 1 to the variable N3.
In step S924, the UE430 determines whether the variable N3 is less than a third predetermined number N3. If the judgment variable N3 is smaller than the third predetermined number N3, the flow returns to step S906. If the judgment variable N3 is not less than the third predetermined number N3, the flow returns to step S904.
It should be noted that the first predetermined number Nl, the second predetermined number N2, and the third predetermined number N3 can refer to the above-mentioned embodiments 0 to 4.
Fig. 10 is a flowchart of a timing adjustment method in a non-terrestrial network (NTN) according to an embodiment of the present invention. Please refer to fig. 4 and fig. 10.
In step S1010, the UE430 performs initial propagation delay pre-compensation. For example, when the UE430 starts to perform initial propagation delay pre-compensation, the UE430 may set variables n, n1, n2, and n3 to initial values 0, where the variables n, n1, n2, and n3 are natural numbers.
In step S1020, the UE430 performs signal transmission to the satellite 410 through the gateway 425.
In step S1030, the UE430 determines whether the number of times of signal transmission performed is lower than a predetermined parameter (e.g., TransMax) in response to the determination that the signal transmission failed.
In step S1040, the UE430 performs a timing adjustment mechanism to use S (n)2) The sequence of steps at shifts the timing of the signal transmission. For example, Δ t represents the minimum time shift unit (e.g., which may be a few microseconds) defined in the transmission protocol (e.g., LTE) used by UE 430; function S (n)2) Indicating the adjustment step size per offset.
In view of the foregoing, an apparatus and method are provided that can perform a timing adjustment mechanism for signal transmissions in a non-terrestrial network (NTN) and allow a UE to better guess an initial time of the signal transmission on a first attempt. Once a successful signal transmission is performed in the first attempt, no subsequent signal transmission retries are required. In addition, the device and the method provided by the invention can also determine the drift rate and the sign bit thereof in various ways, thereby accurately determining the time sequence required for pre-compensating the propagation delay from the UE to the satellite through the gateway.
While the invention has been described by way of examples and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Accordingly, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims (20)
1. A timing adjustment method comprises the following steps:
obtaining a predetermined initial timing of signal transmission from a user equipment to a satellite through a gateway in a non-terrestrial network; and
in response to the number of failures in the signal transmission being greater than or equal to a first predetermined number, shifting, with the user equipment, timing for a subsequent signal transmission using a timing adjustment mechanism.
2. The timing adjustment method of claim 1, wherein the timing adjustment mechanism is performed by the UE to offset the timing of each round of signal transmission when the UE cannot obtain sign bit information of the propagation delay drift rate from the UE to the satellite through the gateway, wherein the timing adjustment mechanism uses an alternating positive and negative sequence.
3. The timing adjustment method of claim 2, wherein the positive and negative alternating sequence is S (n)2) Δ t, and function S (n)2) Expressed as:
where Δ t represents the minimum time shift unit defined in the transmission protocol used by the user equipment, the function S (n)2) Denotes the adjustment step size per offset, and n2Is an integer between 0 and a second predetermined number.
4. The timing adjustment method of claim 3, further comprising: the second predetermined amount is set by obtaining maximum drift rate information of the propagation delay, wherein the maximum drift rate information is broadcast through system information or from the internet.
5. The timing adjustment method of claim 3, wherein the Δ t is half of a cyclic prefix length.
6. A timing adjustment method comprises the following steps:
performing, with a user equipment, the steps of:
estimating drift rate and sign bit of propagation delay from the user equipment to the satellite through a gateway of a base station in the non-terrestrial network; and
a timing adjustment mechanism is implemented to adjust the timing of signal transmissions from the user equipment to the satellite through the gateway using the estimated drift rate and its sign bit.
7. The timing adjustment method of claim 6, wherein the step of estimating a drift rate of a propagation delay from the user equipment to a satellite through a gateway of a base station in a non-terrestrial network and a sign bit thereof comprises:
acquiring ephemeris data of the satellite in the non-ground network;
obtaining the position information of the gateway of the base station in the non-ground network;
calculating the position and track information of the satellite by using the acquired ephemeris data;
acquiring location information of the user equipment from a global navigation satellite system sensor provided in the user equipment;
calculating a propagation delay by dividing a relative distance between the user equipment and the satellite through the gateway by the speed of light; and
and estimating the drift rate and the sign bit of the propagation delay according to the calculated satellite trajectory information.
8. The timing adjustment method of claim 6, wherein the step of estimating a drift rate of a propagation delay from the user equipment to a satellite through a gateway of a base station in a non-terrestrial network and a sign bit thereof comprises:
performing, with the user equipment, the steps of:
performing an estimation algorithm to estimate a timing offset of a downlink channel from the satellite to the user equipment;
estimating the drift rate and sign bit of the downlink channel using the estimated timing offset of the downlink channel; and
setting the drift rate and sign bit of the downlink channel to the drift rate and sign bit of the uplink channel from the user equipment to the satellite.
9. The timing adjustment method of claim 6, wherein the step of estimating a drift rate of a propagation delay from the user equipment to a satellite through a gateway of a base station in a non-terrestrial network and a sign bit thereof comprises:
performing, with the user equipment, the steps of:
acquiring information of a northern hemisphere or a southern hemisphere of the user equipment from a global navigation satellite system sensor arranged in the user equipment;
obtaining the northern hemisphere or southern hemisphere information of the gateway;
acquiring latitude information of the satellite; and
and predicting the drift rate and the sign bit of the propagation delay by using the acquired northern hemisphere or southern hemisphere information of the user equipment, the northern hemisphere or southern hemisphere information of the gateway and the latitude information of the satellite.
10. The timing adjustment method of claim 6, wherein the step of estimating a drift rate of a propagation delay from the user equipment to a satellite through a gateway of a base station in a non-terrestrial network and a sign bit thereof comprises:
performing, with the user equipment, the steps of:
the drift rate of the propagation delay of the satellite is acquired through broadcasting system information or the internet.
11. A user equipment for timing adjustment, comprising:
processing circuitry configured to perform:
obtaining a predetermined initial timing of signal transmission from the user equipment to a satellite through a gateway in a non-terrestrial network; and
in response to the number of failures in the signal transmission being greater than or equal to a first predetermined number, shifting, with the user equipment, timing for a subsequent signal transmission using a timing adjustment mechanism.
12. The user equipment of claim 11 wherein the processing circuit implements the timing adjustment mechanism to offset the timing of each round of signal transmission when sign bit information of a propagation delay drift rate from the user equipment to the satellite through the gateway is not available to the processing circuit, wherein the timing adjustment mechanism uses an alternating positive and negative sequence.
13. As claimed inThe UE of claim 12, wherein the positive-negative alternating sequence is S (n)2) Δ t, and function S (n)2) Expressed as:
where Δ t represents the minimum time shift unit defined in the transmission protocol used by the user equipment, the function S (n)2) Denotes the adjustment step size per offset, and n2Is an integer between 0 and a second predetermined number.
14. The UE of claim 13, wherein the processing circuit sets the second predetermined amount by obtaining maximum drift rate information of the propagation delay, wherein the maximum drift rate information is broadcasted by system information or from the Internet.
15. The user equipment of claim 13 wherein the at is half a cyclic prefix length.
16. A user equipment for timing adjustment, comprising:
processing circuitry configured to perform the steps of:
estimating drift rate and sign bit of propagation delay from the user equipment to the satellite through a gateway of a base station in the non-terrestrial network; and
a timing adjustment mechanism is implemented to adjust the timing of signal transmissions from the user equipment to the satellite through the gateway using the estimated drift rate and its sign bit.
17. The user equipment of claim 16 wherein the processing circuit is further configured to perform:
acquiring ephemeris data of the satellite in the non-ground network;
obtaining the position information of the gateway of the base station in the non-ground network;
calculating the position and track information of the satellite by using the acquired ephemeris data;
acquiring location information of the user equipment from a global navigation satellite system sensor provided in the user equipment;
calculating a propagation delay by dividing a relative distance between the user equipment and the satellite through the gateway by the speed of light; and
and estimating the drift rate and the sign bit of the propagation delay according to the calculated satellite trajectory information.
18. The user equipment of claim 16 wherein the processing circuit is further configured to perform:
performing an estimation algorithm to estimate a timing offset of a downlink channel from the satellite to the user equipment;
estimating the drift rate and sign bit of the downlink channel using the estimated timing offset of the downlink channel; and
setting the drift rate and sign bit of the downlink channel to the drift rate and sign bit of the uplink channel from the user equipment to the satellite.
19. The user equipment of claim 16 wherein the processing circuit is further configured to perform:
acquiring information of a northern hemisphere or a southern hemisphere of the user equipment from a global navigation satellite system sensor arranged in the user equipment;
obtaining the northern hemisphere or southern hemisphere information of the gateway;
acquiring latitude information of the satellite; and
and predicting the drift rate and the sign bit of the propagation delay by using the acquired northern hemisphere or southern hemisphere information of the user equipment, the northern hemisphere or southern hemisphere information of the gateway and the latitude information of the satellite.
20. The user equipment of claim 16 wherein the processing circuit is further configured to perform:
the drift rate of the propagation delay of the satellite is acquired through broadcasting system information or the internet.
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| TW110124400A TWI797663B (en) | 2020-07-03 | 2021-07-02 | Timing adjustment mechanism for signal transmission in non-terrestrial network |
| US17/366,408 US20220007323A1 (en) | 2020-07-03 | 2021-07-02 | Timing adjustment mechanism for signal transmission in non-terrestrial network |
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| PCT/CN2020/100238 WO2022000493A1 (en) | 2020-07-03 | 2020-07-03 | Method and system for timing handling mechanisms for integration terrestrial networks and non terrestrial network |
| CNPCT/CN2020/100238 | 2020-07-03 |
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