WO2022000493A1 - Method and system for timing handling mechanisms for integration terrestrial networks and non terrestrial network - Google Patents
Method and system for timing handling mechanisms for integration terrestrial networks and non terrestrial network Download PDFInfo
- Publication number
- WO2022000493A1 WO2022000493A1 PCT/CN2020/100238 CN2020100238W WO2022000493A1 WO 2022000493 A1 WO2022000493 A1 WO 2022000493A1 CN 2020100238 W CN2020100238 W CN 2020100238W WO 2022000493 A1 WO2022000493 A1 WO 2022000493A1
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- WIPO (PCT)
- Prior art keywords
- information
- propagation delay
- timing
- satellite
- transmission
- Prior art date
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Classifications
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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
-
- 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
-
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W28/00—Network traffic management; Network resource management
- H04W28/02—Traffic management, e.g. flow control or congestion control
- 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
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W56/00—Synchronisation arrangements
- H04W56/004—Synchronisation arrangements compensating for timing error of reception due to propagation delay
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- 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]
- H04W84/04—Large scale networks; Deep hierarchical networks
- H04W84/06—Airborne or Satellite Networks
Definitions
- UE calculates the position and trajectory information of satellite by Ephemeris of satellite, which can be broadcasted by system information or Internet.
- UE gets its own position information by GNSS.
- UE gets the position information of gateway of base station by system information or Internet.
- UE calculates and pre-compensates the initial propagation delay for UE ⁇ ->SAT ⁇ ->GW very precisely. Then the residual propagation delay may be solved by timing adjustment mechanism mainly by propagation delay drifting.
Abstract
There is long dynamic propagation delay in non Terrestrial Network (NTN) than integration Terrestrial Networks (TN). The invention introduces methods of transmission timing adjustment mechanism for non-terrestrial network, wherein shift the transmission timing over the pre-determined timing when failure event is detected.
Description
The present disclosure is generally related to wireless communication, and, more particularly, to a transmission timing adjustment mechanism for Non Terrestrial Network (NTN) .
Non Terrestrial Network (NTN) can provide communication services in areas without Terrestrial Network (TN) services, such as the ocean, desert, mountain, high altitude areas, etc. In addition, NTN communication can also be used as a backup scheme for TN. When the TN service is unavailable for some reasons, the terminal device can try to communicate through the NTN. The NTN communication and the TN communication have different physical characteristics in time delay.
Signal time delay in NTN:
Because the communication distance between the terminal device and the satellite changes with the movement of the satellite, compared with the TN communication system, the signal delay of the NTN is relatively large and time varying. Taking the GEO satellite with an altitude of 35778 kms as an example, and assuming that a base station is on the ground, the elevation angle between satellite and both the terminal device and gateway of the base station is 10 degrees, the round-trip propagation delay from the terminal device to the satellite then to gateway drifts between 535.4ms and 514.4ms in 24 Hours, and the maximum drift rate is +/-0.25us/sas shown in FIG. 1. FIG. 1 shows the round-trip propagation delay of GEO with an altitude of 35778km. Taking the LEO satellite with an altitude of 600 kms as an example as shown in FIG. 2, and assuming that base station is on the ground, the terminal device enters the coverage of the satellite at an elevation of 10 degrees, the round-trip propagation delay from the terminal device to the satellite then to the gateway drifts between 10ms and 26ms in coverage of the satellite as the satellite is moving, the maximum drift rate is +/-80us/sas shown in FIG. 2. FIG. 2 shows the round-trip propagation delay of LEO with an altitude of 600 kms.
In order to use radio resources more efficiently and integrate NTN and TN more efficiently, NTN can divide propagation delay into two parts. Taking the location of the nearest distance between the terminal device and the satellite in a cell as a reference point, the propagation delay of this point is set as the common propagation delay. The propagation delay of other locations in the cell can be further divided into the common propagation delay and the residual propagation delay, as shown in FIG. 3. FIG. 3 shows a common propagation delay and residual propagation delay of LEO satellites, assuming that the beam layout is based on 3dB coverage angle (θ
3dB) .
The common propagation delay in the beam can be compensated by the satellite or the terminal device, and the delay of residual propagation is supported by communication system design.
SUMMARY
There are long dynamic propagation delay in NTN system, although the common propagation delay have been pre-compensated as shown in background, the residual propagation delay by pre-compensation error and the propagation delay drift will still introduce timing deviation in signal transmission. The invention introduces a method for adjusting the transmission timing to solve timing error caused by long dynamic propagation delay in NTN system, wherein the method includes shifting the transmission timing over the pre-determined timing when a failure event is detected.
FIG. 1 shows the round-trip propagation delay of GEO with an altitude of 35778km.
FIG. 2 shows the round-trip propagation delay of LEO with an altitude of 600km.
FIG. 3 shows the common propagation delay and residual propagation delay of satellites.
FIG. 4 shows the transmission timing adjustment mechanism for NTN.
FIG. 7 shows the embodiment with S (n
2) =n
2, n
2=0, 1, …, N
2 and Δt=CP
len.
FIG. 8 shows the embodiment with S (n
2) =-n
2, n
2=0, 1, …, N
2 and Δt=CP
len.
DETAILED DESCRIPTION OF PREFERRED IMPLEMENTATIONS
The invention introduces methods for adjusting transmission timing to solve timing error caused by long dynamic propagation delay in NTN system, wherein the methods include shifting the transmission timing over the pre-determined timing when failure event is detected.
References will now be made in details to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.
One embodiment of transmission timing adjustment mechanism described in FIG. 4:
Step 1: Repeatedly transmitting signals based on pre-determined timing N
1 times. Here the signal may but not limited in various channels or singles or procedures in communication system, such as PRACH, PUSCH, PUCCH and so on. If the signal is transmitted unsuccessfully within N
1 times, the flow goes to step 2, otherwise ends the signal transmission.
Step 2: Shifting the transmission timing over the pre-determined timing, then the flow goes back to Step 1. Timing can be dynamically adjusted according to different application scenarios, may but not limited to accompanying specific embodiments.
Embodiments of pre-determined timing
Case 0-1:
One embodiment of precisely initial propagation delay pre-compensation by location information of UE and satellite and gateway of base station. UE calculates the position and trajectory information of satellite by Ephemeris of satellite, which can be broadcasted by system information or Internet. UE gets its own position information by GNSS. UE gets the position information of gateway of base station by system information or Internet. By the position of UE and satellite and gateway of base station and light speed, UE calculates and pre-compensates the initial propagation delay for UE<->SAT<->GW very precisely. Then the residual propagation delay may be solved by timing adjustment mechanism mainly by propagation delay drifting.
Case 0-2:
One embodiment of roughly initial propagation delay pre-compensation by a fixed value per beam. Then the residual propagation delay may be solved by timing adjustment mechanism mainly by pre-compensation error and propagation delay drifting.
Embodiments of failure event is detected
Case 1-1:
One embodiment of failure event is detected, if the signal transmission fails after transmission N
1 times which can ensure the reliable signal transmission under the correct timing, start-up the transmission timing adjustment mechanism. Take preamble transmission in LTE system as an example, if the transmissions times exceed preambleTransMax, it is considered that the transmission reliability meets the requirements, so N
1 can be preambleTransMax.
Case 1-2:
One embodiment of failure event is detected, the transmission timing adjustment mechanism is started, after the first transmission fails, with a round of timing shift adjustment, it returns to the pre-determined timing and adjusts the power to retransmission. That means the transmission timing adjustment mechanism carried out firstly to calibrate the timing error, and then retransmit to ensure the reliability of the signal transmission. Take preamble transmission in LTE system as an example, assume N
3 is the maximum number of the round of timing shift adjustment as shown in FIG. 4, so N
3 can be preambleTransMax, N
1=1. In order to realize the signal timing alignment of base station and UE as soon as possible, the maximum power can be used in the first round transmission.
Case 1-3:
One embodiment of failure event is detected. N
1 and N
3 can be Random combination as long as satisfy N
1+N
3= preambleTransMax.
Embodiments of timing adjustment mechanism
For convenience of expression, assume the shift value expressed by sequence of S (n
2) *Δt, wherein Δt is smallest shift unit; the elements of S (n
2) is adjustment steps per shift; n
2 is the shifting number.
Case 2-1:
One embodiment of timing adjustment mechanism, which assumed no information of the sign bit of drift rate of propagation delay. In order to cover propagation delay drifting in both negative and positive direction, adjust timing shift of transmission by positive and negative alternating sequence. Such as
n
2=0, 1, …, N
2, Δt =CP
len, as shown in FIG. 5, where CP
len is the maximum tolerable timing error range for normal signal transmission. The first round of signal transmission pre-compensates the propagation delay of T
init, the second round of signal transmission pre-compensate the propagation delay of T
init+CP
len, the third round of signal transmission pre-compensate the delay of T
init-CP
len, and so on, until signal was detected by base station successfully.
Case 2-2:
One embodiment of timing adjustment mechanism, which assumed no information of the sign bit of drift rate of propagation delay, but the initial propagation delay have been pre-compensated precisely enough, so it is better that signal transmit successfully in pre-determined timing. Take preamble transmission in legacy TN system, timing error of signal always positive, but in NTN system, the propagation delay may drift negatively, so the first round of preamble transmission should pre-compensate the delay of T
init+CP
len/2 to tolerance of small positive and negative drift of propagation delay. So in this case as shown in FIG. 6, set
n
2=0, 1, …, N
2, such as {1, 0 , 2, -1, 3, -2, …} , and Δt=CP
len/2.
Case 2-3:
One embodiment of timing adjustment mechanism shown in FIG. 7, which assumed have information of the sign bit of drift rate of propagation delay is negative. In this case, the propagation delay just drift negative, adjust timing shift of transmission by increasing sequence, so set S (n
2) =n
2, n
2=0, 1, …, N
2 and Δt=CP
len.
Case 2-4:
One embodiment of setting the shifting sequence and shifting unit S (n
2) *Δt shown in FIG. 8, have information of the sign bit of drift rate of propagation delay is positive. In this case, the propagation delay just drift larger and larger, adjust timing shift of transmission by decreasing sequence, so set S (n
2) =-n
2, n
2=0, 1, …, N
2 and Δt=CP
len.
Embodiments of setting the maximum timing shifting times
Case 3-1:
One embodiment of setting the maximum shifting times N
2. Assume have information of maximum propagation delay drift rate (d_rate
max) of the satellite, which may but not limited to be broadcast by system information or Internet. Assume the period of updating location information is Period
location, which may but not limited to be broadcast by system information or Internet. If propagation delay drift is both negative and positive, such as Case2-1 and Case2-2, set
If propagation delay drift is in one direction, such as Case2-3 and Case2-4, set
Take LEO with height of 600km and NBIOT as example, as shown in FIG. 2, d_rate
max=+/-80us/s, the CP length is 266us of NBIOT preamble format 1, Δt =CP/2=133us, assume Period
location = 2.5s, N
2= 4. Different cells can have different shifting window times.
Case 3-2:
One embodiment of setting the maximum shifting times N
2 based on Case 3-1, have information of precise delay drift rate,
or
Embodiments of getting the sign bit of drift rate of propagation delay
Case 4-1:
One embodiment of getting the sign bit of drift rate of propagation delay. The drift rate of propagation delay can be estimated precisely by precise location information of UE and satellite and gateway of base station. Ephemeris of satellite can be broadcasted by system information or Internet, UE calculates the position and trajectory information of satellite by ephemeris. UE gets its own position information by GNSS. UE gets the position information of gateway of base station by system information or Internet.
Case 4-2:
One embodiment of getting the sign bit of drift rate of the satellite. UE can estimate the drift rate of the propagation delay according to the estimation algorithm of the downlink timing offset. The uplink drift rate can be approximate to the downlink drift rate.
Case 4-3:
One embodiment of getting the sign bit of drift rate of satellite, according to rough latitude information of UE and Gateway of Base station, and the propagation delay drift curve of satellite, UE can predict the drift curve of propagation delay and get the rate of timing drift by time. For example, UE gets the northern or southern hemisphere information of UE by GNSS or fixed information; UE gets the northern or southern hemisphere information of GW of base station by system information or Internet or fixed information; UE gets the approximate latitude information of satellite by system information or Internet or fixed information. Take GEO with height of 35778km as example, with those information, the drift rate of propagation delay is negative in the first half of the day, the drift rate of propagation delay is positive in the second half of the day, as shown in FIG. 1.
In the above-mentioned embodiments, it is assumed that initial propagation delay is compensated. In fact, if initial propagation delay is not compensated, the above-mentioned embodiment will still be used, except the scope of signal shifting are larger.
For integration TN and NTN system, the above-mentioned embodiments are also applicable to TN system, except the signal transmission is successful in the first round, so no need to shifting transmit.
Claims (20)
- A method of transmission timing adjustment mechanism for non-terrestrial network, comprising: shifting the transmission timing over the pre-determined timing when failure event is detected.
- The method of claim 1, wherein the pre-determined timing is initial propagation delay pre-compensated by location information of UE and satellite and gateway of base station.
- The method of claim 1, wherein the pre-determined timing is initial propagation delay pre-compensated by a fixed value per beam.
- The method of claim 1, wherein the failure event is detected if the signal transmission fail after transmission N 1 times, which can ensure the reliable signal transmission under the correct timing.
- The method of claim 1, wherein the failure event is detected if the first transmission failure. With a round of timing shift adjustment, it returns to the pre-determined timing and adjusts the power to retransmission.
- The method of claim 1, wherein the timing adjustment mechanism is shift the timing of each group of transmissions by a positive and negative alternating sequence, which assumed have no information of the sign bit of drift rate of propagation delay.
- The method of claim 1, wherein the timing adjustment mechanism shift the timing of each group of transmissions by increasing sequence or decreasing sequence, which assumed have information of the sign bit of drift rate of propagation delay.
- The method of claim 1, wherein the increasing sequence is S (n 2) = n 2, n 2=0, 1, …, N 2 and Δt = CP len.
- The method of claim 1, wherein the decreasing sequence is S (n 2) =-n 2, n 2=0, 1, …, N 2 and Δt = CP len.
- The method of claim 9, wherein the sign bit of drift rate of propagation delay can be estimated precisely by precise location information of UE and satellite and gateway of base station.
- The method of claim 9, wherein the sign bit of drift rate of propagation delay can be estimated by rough latitude information of UE and Gateway of Base station, and the propagation delay drift curve of satellite.
- The method of claim 14, wherein the position information of satellite can be got by Ephemeris of satellite, which can be broadcasted by system information or Internet.
- The method of claim 14, wherein the position information of gateway of base station can be got by system information or Internet.
- The method of claim 15, wherein rough latitude information of UE is northern or southern hemisphere information, which can be got by GNSS or fixed information.
- The method of claim 15, wherein rough latitude information of GW is northern or southern hemisphere information, which can be got by system information or Internet or fixed information.
- The method of claim 15, wherein the propagation delay drift curve of satellite can be Internet or system information or fixed information.
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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 |
CN202110733833.9A CN114095861A (en) | 2020-07-03 | 2021-06-30 | Timing adjustment mechanism for signal transmission in non-terrestrial networks |
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 |
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US20190394770A1 (en) * | 2018-06-20 | 2019-12-26 | Qualcomm Incorporated | Upstream timing control mechanisms for non-terrestrial networks |
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US9055528B2 (en) * | 2013-02-06 | 2015-06-09 | Qualcomm Incorporated | Determination of NCS parameter and logical root sequence assignments |
WO2020071698A1 (en) * | 2018-10-05 | 2020-04-09 | 주식회사 케이티 | Method for performing communication by using non-terrestrial network and apparatus thereof |
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US20190313357A1 (en) * | 2018-04-05 | 2019-10-10 | Qualcomm Incorporated | Techniques for initial access in wireless systems |
US20190394770A1 (en) * | 2018-06-20 | 2019-12-26 | Qualcomm Incorporated | Upstream timing control mechanisms for non-terrestrial networks |
WO2020075044A1 (en) * | 2018-10-08 | 2020-04-16 | Telefonaktiebolaget Lm Ericsson (Publ) | Adapting phy layer procedures for a moving ran in non-terrestrial networks |
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Non-Patent Citations (1)
Title |
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HUAWEI, HISILICON: "Discussion on timing advance and RACH procedures for NTN", 3GPP DRAFT; R1-1904000, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, vol. RAN WG1, no. Xi’an, China; 20190408 - 20190412, 7 April 2019 (2019-04-07), Mobile Competence Centre ; 650, route des Lucioles ; F-06921 Sophia-Antipolis Cedex ; France , XP051699411 * |
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