WO2012109931A1

WO2012109931A1 - Lte time adjustment method and base station

Info

Publication number: WO2012109931A1
Application number: PCT/CN2011/082286
Authority: WO
Inventors: 余秋星; 陈琼
Original assignee: 中兴通讯股份有限公司
Priority date: 2011-02-17
Filing date: 2011-11-16
Publication date: 2012-08-23
Also published as: CN102647780A

Abstract

Disclosed are an LTE time adjustment method and a base station. A time offset instantaneous value of a target user equipment is measured and recorded by the base station, and a smoothed time offset value for the target user equipment is calculated on the basis of the time offset instantaneous value of the target user equipment. Before an activated timing advance (TA) timer expires, a timing advance adjustment command is issued on the basis of the smoothed time offset value of the target user equipment. In the LTE time adjustment method and the base station provided in the present invention, a plurality of time offset measurement values of a relatively smaller quantity are averaged, then the average values are smoothed, and the smoothed value is compared against a time offset expected value, and the timing advance adjustment command to be issued to the target user equipment is confirmed, thus improving the accuracy of time offset measurement, while also preventing multiple inaccurate adjustments, and improving greatly the accuracy and efficiency of timing advance adjustment.

Description

LTE time adjustment method and base station

The present invention relates to the field of wireless communication technologies, and specifically relates to a time adjustment method for LTE (Long Term Evolution) and a base station. Background technique

In the LTE system, Time Advance (TA) is a parameter used to characterize the timing deviation of the data transmitted by the UE (User Equipment) received by the eNodeB (evolved NodeB). In order to maintain the uplink synchronization, the eNodeB instructs the UE to send a DMRS (Demodulation Reference Signal) or a SRS (Sounding Reference Signal) at a specified time point, and obtains a TA after timing measurement, and the eNodeB passes the physical downlink shared channel. The time advance adjustment command is sent to the UE for adjustment to maintain uplink synchronization between the UE and the eNodeB.

In LTE, the time advance adjustment command is expressed in multiples of 16 times Ts (ITs is the basic time unit of LTE) with respect to the current uplink timing, and is MAC (Medium/Media Access Control). Control) the control unit to deliver. The time adjustment command ⁷ carrying 6 bits in the time adjustment MAC control unit is used to indicate the absolute adjustment amount ^ relative to the current. "The relative adjustment amount, the value range is: ⁰ , ¹ ,..., ⁶³ , then the new absolute adjustment is expressed as ^ ^w + (^ ~ ^{31) χ16} , the unit is Ts

In the prior art, the base station generally obtains a smoothed value according to the measured instantaneous TA value or based on the instantaneous value, and then notifies the UE to perform TA adjustment. When the uplink signal-to-noise ratio is low, the measured instantaneous value is easily affected by noise and interference and becomes inaccurate, and even the result of the TA measurement at the adjacent time fluctuates within a wide range, so the time advance is performed based on the prior art. Adjustment will make When the base station processes the uplink received signal, its Fourier transform (FFT) window contains information of adjacent symbols, introducing inter-symbol interference (ISI), thereby greatly degrading the performance of the uplink demodulation test signal, so that the system The throughput is decreasing. Summary of the invention

The main object of the present invention is to provide a time adjustment method and base station for LTE to improve the accuracy and efficiency of time advance adjustment.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A time adjustment method for LTE, including:

The base station measures and records the time-offset instantaneous value of the target user equipment, and calculates a smoothing time offset value of the target user equipment according to the instantaneous time-offset value of the target user equipment;

And according to the smoothed time offset value of the target user equipment, the time advance adjustment command is issued before the time advance TA timer expires.

After the TA timer expires and the time advance adjustment command is issued, the method further includes: measuring and recording the time offset value of the target user equipment after receiving the confirmation information of the target user equipment.

The condition for starting the TA timer is: the user equipment completes the random access procedure, or the base station completes the delivery timing advance adjustment command.

The measuring and recording the time-averaged instantaneous value of the target user equipment includes:

Calculating the time-offset instantaneous value according to a channel response phase difference between adjacent or spaced subcarriers of the uplink demodulation reference signal or the sounding reference signal, or

The time-offset instantaneous value is obtained by estimating an arrival time of the first path or the strongest path of the channel according to the uplink demodulation reference signal or the sounding reference signal.

The calculating the smoothing time offset value of the target user equipment according to the time-offset instantaneous value of the target user equipment, including:

During the period of the TA timer timeout value, the measurement is performed to obtain multiple time-offset instantaneous values, which will be connected. The continuation time is divided into a group, the average value of each group is calculated, and then the average value of each group is smoothed to obtain a smoothing time value.

The time advance adjustment command is sent according to the smoothing time offset value of the target user equipment before the TA timer expires, including:

When the absolute value of the difference between the smoothed time offset value and the TA expected value exceeds a predefined time offset threshold value, the time advance adjustment command TAC is issued;

When the absolute value of the difference between the smoothed offset value and the TA expected value does not exceed the predefined time offset threshold, the time advance adjustment command C is issued before the TA timer expires.

The time advance adjustment command sent according to the following steps is generated: when the difference between the offset value and the TA expected value is greater than a predefined time offset threshold, the time advance adjustment command is ₃₂ ; or

When the difference between the TA expected value and the smoothed offset value is greater than a predefined time offset threshold, the time advance adjustment command is ₃₀ ; or,

A base station comprising:

a timer start unit, configured to start a TA timer;

a measurement recording unit, configured to measure and record a time-series instantaneous value of the target user equipment; and a calculation processing unit, configured to calculate a smoothing time offset value of the target user equipment according to the time-offset instantaneous value of the target user equipment;

The adjustment command issuing unit is configured to send a time advance adjustment command before the TA timer expires according to the smoothing time offset value of the target user equipment.

The method further includes: a repeating unit, configured to measure and record a time-offset instantaneous value of the target user equipment after receiving the confirmation information of the target user equipment.

The timer starting unit is configured to complete the random access procedure according to the user equipment, or start the TA timer when the base station sends a timing advance adjustment command. The measurement recording unit is configured to calculate the time-offset instantaneous value according to a channel response phase difference between adjacent or separated sub-carriers of the uplink demodulation reference signal or the sounding reference signal, or

The calculation processing unit is configured to perform measurement to obtain a plurality of time-offset instantaneous values in a period of the TA timer timeout value, and divide the consecutive L time-offset instantaneous values into a group, and calculate an average value of each group. Then, smooth the average of each group to obtain the smoothing time offset value.

The adjustment command issuing unit is configured to:

When the absolute value of the difference between the smoothed offset value and the TA expected value exceeds a predefined time offset threshold value, the time advance adjustment command c is issued;

The adjustment command issuing unit is configured to: when the difference between the offset value and the TA expected value is greater than a predefined time offset threshold, the time advance adjustment command is ₃₂ ; or ,

The technical solution of the present invention has the following beneficial effects: The LTE time adjustment method and the base station provided by the present invention first average a plurality of time-biased measurement values, and then smooth the average values, and obtain The smoothing value is compared with the time-biased expectation value to determine the time advance adjustment command for the target user equipment, so that the accuracy of the time-offset measurement can be improved, and the measurement uncertainty caused by the time-bias measurement being affected by noise and interference can be avoided. The time adjustment is inaccurate in advance, and even causes the problem of uplink out-of-step, especially when the signal-to-noise ratio is greatly improved. The accuracy of the adjustment in advance; and greatly reduces the implementation complexity of the time advance adjustment. By setting the statistical length parameter, the reliability of the time advance adjustment can be improved for the discontinuous scheduling and the continuous read scheduling situation; since the measurement of the record is started after receiving the confirmation message of the information adjusted by the user equipment in advance. The instantaneous value is offset, so that incorrect adjustments can be avoided multiple times, which greatly improves the adjustment accuracy and efficiency of time advancement, thereby ultimately improving system throughput. DRAWINGS

1 is a flowchart of a method according to an embodiment of the present invention;

2 is a flow chart of a method according to another embodiment of the present invention;

3 is a schematic structural diagram of a base station according to an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a base station according to another embodiment of the present invention. detailed description

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The embodiment of the present invention provides a time adjustment method for LTE. The steps of the method may be implemented by a base station. As shown in FIG. 1, the method includes the following steps:

S110. The base station starts the TA timer. In other embodiments, the condition for starting the TA timer is: the user equipment completes the random access procedure, or the base station completes the delivery timing advance adjustment command.

S120. Measure and record a time-biased instantaneous value of the target user equipment.

In other embodiments, S 120 may further include:

Calculating the time-offset instantaneous value according to a channel response phase difference between adjacent or spaced subcarriers of the uplink demodulation reference signal or the sounding reference signal; or estimating the first path of the channel according to the uplink demodulation reference signal or the sounding reference signal Or the strongest diameter (the strongest diameter is: the most powerful The arrival time of the force) to obtain the instantaneous value of the time.

S130. Calculate a smoothing time offset value of the target user equipment according to a time-offset instantaneous value of the target user equipment.

During the period of the TA timer timeout value, multiple time-offset instantaneous values are measured, and successive time-offset instantaneous values are grouped into one group, and the average value of each group is calculated, and then the average value of each group is smoothed to obtain smoothing. Time offset value.

For example: Suppose that the time-offset instantaneous value obtained in the TA timer timeout value is ^ ⁴ ^ , ^{k =} U , which is the index of the number of time-series values according to the chronological order, then calculate the continuous time-series values according to the following formula. Average: :丄⁰ ί

L t=io(i-i)+i i = 1,2,..., .

Where M = ^ / ", L." means rounding down.

The following methods can be used to calculate the smoothing time offset of the target user equipment:

Smoothing the average of each group to obtain the smoothing time offset value ^ ⁴² '' ( i = 2 .., M _)?

TA2 _i = (1 - α)23⁄42 + - TA i = 2,3,...,M .

Where Τ^ ΤΜ^ is the smoothing coefficient, 0 < ≤1.

S140: According to the smoothing time offset value of the target user equipment, send a time advance adjustment command before the TA timer expires, and restart the TA timer.

In other embodiments, more specifically, when the absolute value of the difference between the smoothed time offset value and the TA expected value exceeds a predefined time offset threshold value, the time advance adjustment command is issued;

More specifically, it is necessary to set the TA adjustment expectation value ⁷ and the defined time deviation threshold value ^^. _ω . Comparing the smoothing value of the bias value ⁷ ^ ² ; the absolute value of the difference between the expected value and the pre-defined time-biased gate The size of the limit value ⁷ , combined with the TA timer, is issued in advance to adjust the command:

When the absolute value of the difference between the offset ² '· and the expected value exceeds the predefined time offset threshold, the time advance adjustment command is issued.

The time advance adjustment command can be generated by a slow adjustment method or a quick adjustment method.

Before the TA timer expires, the difference between the calculated smoothing time offset value ² '· and the expected value _t is compared with the TA threshold value ⁷ , and a time advance adjustment command is generated according to the comparison result: if ^^ is subtracted ^ is greater than ⁷ ^^. , the time advance adjustment command is 23⁄4C = ³² , and the TA is gradually adjusted to the vicinity of the expected value;

If ⁷ ^ ² '· subtract ⁷ ^ is less than - ⁷ ^^. Then the time advance adjustment command is 23⁄4C = ³ 0 , and the TA is gradually adjusted to the vicinity of the expected value.

It can be seen that the above content is a method of gradually adjusting the time offset to the vicinity of the expected value, which may be referred to as a slow adjustment method.

The quick adjustment method is to generate the time advance adjustment command TAC according to the following formula:

— TA

TAC = round (― + 31

16 · Where round represents the rounding operation, I l> ^Τ When the smoothing time offset ² '· The absolute value of the difference between the expected value does not exceed the predefined time offset threshold ^tow, before the TA timer expires The delivery time is adjusted in advance, and the time advance adjustment command is = ³ 1.

In the LTE system, the preferred value of the time offset threshold is 8.

The base station needs to restart the ΤΑ timer at the same time as the base station adjusts the command in advance. On the basis of the foregoing embodiments, after the time advance adjustment command is issued, the method further includes: S150: After receiving the confirmation information of the target user equipment, measure and record the time-offset instantaneous value of the target user equipment. Specifically, after the base station sends the time advance adjustment command, the user sets The backup needs to correctly parse the time advance command and apply the time advance command after a certain delay. Therefore, before the base station receives the acknowledgement information (ACK) of the correct demodulation of the time advance command of the user equipment, the time offset of the user equipment is the time offset before the time advance adjustment command takes effect; after the base station receives the ACK, the user equipment The time offset value is the time offset value after adjustment. It can be seen that, in S150, the time-offset instantaneous value of the measurement measurement is started after receiving the confirmation message of the time advance adjustment information sent by the user equipment, so that it is possible to avoid incorrectly adjusting the timing advance amount multiple times.

When adjusting the time of LTE, first averaging a plurality of time-biased measurement values, then smoothing each average value, and comparing the obtained smoothed value with the time-biased expected value to determine the target user equipment. The pre-adjustment command is issued in advance, so that the accuracy of the time-offset measurement can be improved, and the inaccurate time adjustment caused by the measurement inaccuracy caused by the noise and the disturbance of the time-biased measurement can be avoided, and even the problem of the uplink out-of-step is caused, especially It greatly improves the accuracy of time advance adjustment under low SNR; and greatly reduces the implementation complexity of time advance adjustment; By setting the statistical length parameter, the time advance can be improved for discontinuous scheduling and continuous read scheduling. The reliability of the adjustment; since the time-offset instantaneous value of the measurement measurement is started after receiving the confirmation message of the advance adjustment information of the user equipment, it is possible to avoid incorrect multiple adjustments, thereby greatly improving the adjustment of the time advancement. Accuracy and efficiency, which ultimately increases system throughput.

An embodiment of the present invention further provides a base station. As shown in FIG. 3, the base station includes:

The timer starting unit 210 is configured to start the TA timer. In other embodiments, the timer starting unit 210 is configured to complete a random access procedure according to the user equipment, or send a timing at the base station. The TA timer is started when the command is adjusted in advance.

The measurement recording unit 220 is configured to measure and record the time-offset instantaneous value of the target user equipment. In other embodiments, the measurement recording unit 220 is configured to demodulate the reference signal or the sounding reference signal according to the uplink. Calculating the time-shifted instantaneous value of the channel response phase difference between adjacent or separated sub-carriers, or estimating according to the uplink demodulation reference signal or the sounding reference signal The time-of-arrival value of the first or most strong path of the channel is obtained.

The calculation processing unit 230 is configured to calculate a smoothing time offset value of the target user equipment according to the time-series instantaneous value of the target user equipment. In other embodiments, the computing processing unit 230 is further It is used to measure multiple time-offset instantaneous values in the period of the TA timer timeout value, divide successive time-offset instantaneous values into one group, calculate the average value of each group, and then perform average value for each group. Smooth, get the smoothing time offset.

The adjustment command issuing unit 240 is configured to send a time advance adjustment command before the TA timer expires according to the smoothing time offset value of the target user equipment, and restart the TA timer. In other embodiments, the adjustment command issuing unit 240 is configured to:

When the absolute value of the difference between the smoothed offset value and the TA expected value does not exceed the predefined time offset threshold, the time advance adjustment command C is issued before the TA timer expires. Further, the time advance adjustment command sent by the adjustment command issuing unit 240 may be generated according to the following steps:

When the difference between the smoothed offset value and the TA expected value is greater than a predefined time offset threshold, the time advance adjustment command is ₃₂ ; or,

In other embodiments, the base station further includes: a repeating unit 250, configured to measure and record a time-offset instantaneous value of the target user equipment after receiving the acknowledgement information of the target user equipment.

The base station provided by the embodiment of the present invention first averages a plurality of time-biased measurement values with a small number, and then smoothes each average value, and compares the obtained smoothed value with the time-biased expected value, and determines the target user equipment accordingly. The time to adjust the command in advance can improve the accuracy of the time-biased measurement. Avoid inaccurate adjustment of time due to measurement inaccuracy caused by noise and interference, and even cause uplink out-of-synchronization, especially greatly improving the accuracy of time advance adjustment under low SNR; Moreover, the implementation complexity of the time advance adjustment is greatly reduced; by setting the statistical length parameter, the reliability of the time advance adjustment can be improved for the discontinuous scheduling and the continuous read scheduling; since the time of receiving the user equipment is adjusted in advance After the confirmation message of the information, the time-biased instantaneous value of the measurement measurement is started, so that the adjustment can be avoided multiple times incorrectly; the adjustment precision and efficiency of the time advancement are greatly improved, thereby finally improving the system throughput.

The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalents, and improvements made within the spirit and scope of the present invention should be included in the scope of the present invention. Inside.

Claims

Claim

1. A time adjustment method for LTE, including:

The method of claim 1, wherein, before the TA timer expires, after the time advance adjustment command is issued, the method further includes: measuring and recording the target user equipment after receiving the confirmation information of the target user equipment Partial instantaneous value.

The method of claim 1 or 2, wherein the condition for starting the TA timer is: the user equipment completes the random access procedure, or the base station completes the delivery timing advance adjustment command.

4. The method according to claim 1 or 2, wherein the measuring and recording the time-offset instantaneous value of the target user equipment comprises:

The method according to claim 1 or 2, wherein the calculating the smoothing time offset value of the target user equipment according to the time-offset instantaneous value of the target user equipment comprises:

During the period of the TA timer timeout value, the measurement is performed to obtain a plurality of time-offset instantaneous values, and the successive time-offset instantaneous values are grouped into one group, the average value of each group is calculated, and then the average value of each group is smoothed. Get the smoothed bias value.

The method according to claim 1 or 2, wherein the time advance adjustment command is issued before the TA timer expires according to the smoothed time offset value of the target user equipment, including:

When the absolute value of the difference between the offset value and the expected value of the TA exceeds the predefined time-deviation threshold When the time is issued, the command is adjusted in advance;

The method of claim 6, wherein the issued time advance adjustment command is generated according to the following steps:

When the bias value vice limit value is greater than the difference between a desired value TA predefined smoothing, the timing advance adjustment command _32; or

8. A base station comprising:

a timer start unit, configured to start a TA timer;

The base station according to claim 8, further comprising: a repeating unit, configured to measure and record a time-offset instantaneous value of the target user equipment after receiving the confirmation information of the target user equipment.

The base station according to claim 8 or 9, wherein the timer starting unit is configured to start the random access procedure according to the user equipment, or start the TA timer when the base station sends a timing advance adjustment command.

The base station according to claim 8 or 9, wherein the measurement recording unit is configured to calculate the time according to a channel response phase difference between adjacent or spaced subcarriers of the uplink demodulation reference signal or the sounding reference signal. Partial instantaneous value, or, The time-offset instantaneous value is obtained by estimating an arrival time of the first path or the strongest path of the channel according to the uplink demodulation reference signal or the sounding reference signal.

The base station according to claim 8 or 9, wherein the calculation processing unit is configured to perform measurement in a period of a TA timer timeout value to obtain a plurality of time-offset instantaneous values, and successive time-offset instantaneous values Divided into one group, the average value of each group is calculated, and then the average value of each group is smoothed to obtain a smoothed time offset value.

The base station according to claim 8 or 9, wherein the adjustment command issuing unit is used to:

The base station according to claim 13, wherein the adjustment command issuing unit is configured to: