CN104080159A - Carrier transmission time setting method and communication system - Google Patents

Abstract

The invention discloses a carrier transmission time setting method and a communication system. The carrier transmission time setting method comprises the following steps: computing time sequence information transmitted specific to each carrier by a base station respectively according to the time advance of each carrier of each terminal; computing time advance time differences between other component carriers and one component carrier taken as a reference according to the time sequence information; and determining the transmission time of each carrier according to the time advance of different terminals on different carriers to ensure that the maximum time difference among carrier signals received by all terminals in a cell meets the requirement of TAE (Time Alignment Error) and corresponding demodulation performance.

Description

Carrier wave transmitting time method to set up and communication system

Technical field

The present invention relates to the communications field, be specifically related to a kind of carrier wave transmitting time method to set up and communication system.

Background technology

The radio-frequency (RF) index TAE(Time Alignment Error of base station, time synchronization error) be the time difference thresholding that unlike signal branch that base station sends arrives same terminal.If the different branch signal differences time of advent that terminal receives are greater than TAE, demodulation performance can drop to not receivable degree, otherwise demodulation performance is not had a significant effect.So, how to ensure that each signal branch difference time of advent of terminal reception, within TAE, is the key that ensures terminal demodulation performance.

According to studies show that: when terminal is used same TAG(to send lead group to different carrier) time, the TAE that 260ns is set can ensure the demodulation performance of terminal; In the time that terminal is used two or more TAG to different carrier, the TAE that 1300ns is set can ensure the demodulation performance of terminal.

In base station radio-frequency performance specification TS36.104, be mainly divided into several classes for the definition of TAE:

1. for many antennas and transmit diversity technique, the TAE on each carrier wave can not be greater than 65ns;

2. for continuous carrier polymerization in band, do not adopt many antennas and transmit diversity technique, TAE can not be greater than 130ns;

3. for discontinuous carrier polymerization in band, do not adopt many antennas and transmit diversity technique, TAE can not be greater than 260ns;

4. for interband carrier aggregation, do not adopt many antennas and transmit diversity technique, TAE can not be greater than 1300ns.

Can find out, for different carrier aggregation scenes, 3GPP specification different TAE values ensure the demodulation performance of terminal.Many time of the current terminal MTA(carrying out at 3GPP RAN2Rel-11 sends lead) problem, specify that terminal need to adopt different Timing Advances to send different branch informations in some scene, to ensure that each branch information arrives base station received, demodulation simultaneously.These branches may be different carriers in carrier aggregation scene, may be also by relay base station or RRH(RF remote) the different propagation paths that cause.In the time that the different paths of different carrier, relay base station or RRH in carrier aggregation adopt different TAG, illustrate between multiple carrier waves or multiple path and have obvious propagation time difference.If send different carrier waves according to prior art base station at synchronization, this time difference may produce obvious negative effect to the demodulation performance of terminal.The carrier wave of multiple TAG in this problem both may also may be from same frequency range (band intercarrier polymerization) from different frequency range (interband carrier aggregation).If according to current TAE define method, be defined as 130ns with the TAE of intercarrier polymerization.According to 3GPP specification, a TA step-length is 520ns.When two carrier waves with intercarrier polymerization adopt different TAG, the terminal of two carrier waves sends lead and at least differs 520ns.According to definition of T A for being round-trip delay (Round Trip Time); the difference that base station sends two carrier waves is not less than 520ns/2=260ns; conventionally base station sends different carrier waves simultaneously, and the difference of two carrier waves that terminal receives is not less than 260ns, can not meet the demand of TAE.

In addition, 3GPP determines the carrier aggregation in descending support RRH and relay base station scene, according to the result of study of RAN2, for these two scenes, no matter be band intercarrier polymerization or interband carrier aggregation, all need to support multiple upper row clocks in advance, need terminal pins to set different TAG to different component carriers.Now, in TS36.104, for thirdly just there will be in the time that terminal adopts different TAG of TAE specification, can not meet the demand of TAE.

Visible, setting is not well positioned to meet the requirement of TAE to each carrier wave transmitting time to adopt prior art.

Summary of the invention

The main technical problem to be solved in the present invention is, a kind of carrier wave transmitting time method to set up and communication system are provided, and solves existingly can not finely meet the requirement of time synchronization error TAE and the problem of corresponding demodulation performance to each carrier wave transmitting time set-up mode.

For solving the problems of the technologies described above, the invention provides a kind of carrier wave transmitting time method to set up, comprising:

Obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; Described i=1 ..., n, described n is more than or equal to 2 integer; Described j=1 ..., m, described m is more than or equal to 2 integer;

From described carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, described terminal A _iat described carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

By described TA _ijwith described TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, described j is not equal to described k;

Based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time.

In an embodiment of the present invention, described carrier wave C _jbe described terminal A for controlling base station _ithe carrier wave providing; Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

By Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)described carrier wave C is set ₁..., C _mtransmitting time.

In an embodiment of the present invention, described m=2, described carrier wave C ₁be described terminal A for controlling base station _ithe carrier wave providing, described carrier wave C ₂for relay base station is described terminal A _ithe carrier wave providing;

Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz;

By described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1z, TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

In an embodiment of the present invention, described m=2, described carrier wave C ₁be described terminal A for controlling base station _ithe carrier wave providing, described carrier wave C ₂for RF remote is described terminal A _ithe carrier wave providing;

Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir;

By described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1r, TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

In an embodiment of the present invention, described in, obtain the terminal A in community, place, base station _iat carrier wave C _jon Timing Advance TA _ijbe specially:

By terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij.

In an embodiment of the present invention, the described class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time comprise:

Reference carrier C is set _ktransmitting time T _k;

Judge the class mean value Δ T of described Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).

In an embodiment of the present invention, described carrier wave C _jfor the different carrier with in interior continuous carrier polymerization, or the different carrier in discontinuous carrier polymerization in band, or different carrier in the polymerization of interband continuous carrier.

In order to address the above problem, the present invention also provides a kind of communication system, comprises the terminal A controlling in base station and community _i; Described i=1 ..., n, described n is more than or equal to 2 integer; Described control base station comprises that Timing Advance acquisition module, reference carrier selection module, Timing Advance difference acquisition module and carrier wave transmitting time arrange module,

Described Timing Advance acquisition module is used for obtaining terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; Described j=1 ..., m, described m is more than or equal to 2 integer;

Described reference carrier selects module to be used for from described carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, described terminal A _iat described carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

Described Timing Advance difference acquisition module is used for described TA _ijwith described TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, described j is not equal to described k;

Carrier wave transmitting time arranges module for based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time.

In an embodiment of the present invention, described carrier wave C _jfor described control base station is described terminal A _ithe carrier wave providing; Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module by Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)described carrier wave C is set ₁..., C _mtransmitting time.

In an embodiment of the present invention, described m=2, described carrier wave C ₁for described control base station is described terminal A _ithe carrier wave providing, described carrier wave C ₂for relay base station is described terminal A _ithe carrier wave providing;

Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz;

Described carrier wave transmitting time arranges module by described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1z, TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

In an embodiment of the present invention, described m=2, described carrier wave C ₁for described control base station is described terminal A _ithe carrier wave providing, described carrier wave C ₂for RF remote is described terminal A _ithe carrier wave providing;

Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir;

Described carrier wave transmitting time arranges module by described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1r, TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

In an embodiment of the present invention, described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module reference carrier C is set _ktransmitting time T _k;

Described carrier wave transmitting time arranges module and judges the class mean value Δ T of described Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).

The invention has the beneficial effects as follows:

Carrier wave transmitting time method to set up provided by the invention and communication system, by obtaining terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; I=1 ..., n, n is more than or equal to 2 integer; J=1 ..., m, m is more than or equal to 2 integer; Then from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; By TA _ijwith TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, j is not equal to described k; Based on Timing Advance difference DELTA TA _{i (k-j)}carrier wave C is set ₁..., C _mtransmitting time; Also be, according to each terminal, the Timing Advance on each carrier wave calculates respectively the time sequence information that base station sends for each carrier wave in the present invention, and according to this time sequence information, taking one of them component carrier as benchmark, calculate other component carriers Timing Advance time difference with it, and then the Timing Advance on different carrier is determined the transmitting time of each carrier wave according to different terminals, to ensure that the maximum time difference between each carrier signal that in community, all terminals receive meets requirement and the corresponding demodulation performance of TAE.

Brief description of the drawings

Fig. 1 arranges carrier wave transmitting time schematic flow sheet one in the embodiment of the present invention one;

Fig. 2 arranges carrier wave transmitting time schematic flow sheet two in the embodiment of the present invention one;

Fig. 3 arranges carrier wave transmitting time schematic flow sheet in the embodiment of the present invention two;

Fig. 4 arranges carrier wave transmitting time schematic flow sheet in the embodiment of the present invention three;

Fig. 5 arranges carrier wave transmitting time schematic flow sheet in the embodiment of the present invention four;

Fig. 6 is the structural representation of controlling base station in the embodiment of the present invention five.

Embodiment

According to each terminal, the Timing Advance on each carrier wave calculates respectively the time sequence information that base station sends for each carrier wave in the present invention, and according to this time sequence information, taking one of them component carrier as benchmark, calculate other component carriers Timing Advance time difference with it, and then the Timing Advance on different carrier is determined the transmitting time of each carrier wave according to different terminals, to ensure that the maximum time difference between each carrier signal that in community, all terminals receive meets requirement and the corresponding demodulation performance of TAE.By reference to the accompanying drawings the present invention is described in further detail below by embodiment.

Embodiment mono-:

Shown in Figure 1, the carrier wave transmitting time method to set up that the present embodiment provides comprises:

Step 101: obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; Wherein, described i=1 ..., n, described n is more than or equal to 2 integer; Described j=1 ..., m, described m is more than or equal to 2 integer;

Step 102: from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

Step 103: by the TA of institute _ijwith TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, wherein, described j is not equal to described k;

Step 104: the Timing Advance difference DELTA TA based on obtaining _{i (k-j)}carrier wave C is set ₁..., C _mtransmitting time.

In the present embodiment, above-mentioned steps 101 specifically can be passed through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij; Because which has been the disclosed mode of this area, no longer it is repeated at this.

Shown in Figure 2, in the present embodiment, the Timing Advance difference DELTA TA based on obtaining _{i (k-j)}carrier wave C is set ₁..., C _mtransmitting time specifically can be further comprising the steps:

Step 1041: the lead difference DELTA TA based on obtaining _{i (k-j)}obtain the class mean value Δ T of Timing Advance difference in conjunction with concrete application scenarios _(k-j);

Step 1042: the class mean value Δ T of the Timing Advance difference based on obtaining _(k-j)carrier wave C is set ₁..., C _mtransmitting time, specific as follows:

Reference carrier C is set _ktransmitting time T _k;

Judge the class mean value Δ T of Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).

Should be understood that the carrier wave C in the present embodiment _jfor the different carrier with in interior continuous carrier polymerization, or the different carrier in discontinuous carrier polymerization in band, or different carrier in the polymerization of interband continuous carrier.

Visible, the present embodiment based on each terminal Ai at each carrier wave C _jon Timing Advance calculate respectively the time sequence information that base station sends for each carrier wave, and then taking one of them component carrier as benchmark, calculate other component carriers Timing Advance time difference with it, then according to different terminals, the Timing Advance on different carrier is determined the transmitting time of each carrier wave, can ensure that the maximum time difference between each carrier signal that in community, all terminals receive meets requirement and the corresponding demodulation performance of TAE.Respectively taking several concrete application scenarioss as example, the present invention is described further below.

Embodiment bis-:

In the present embodiment, establish two component carrier C that control base station employing carrier aggregation ₁and C ₂for terminal A _iservice, wherein, i=1 ..., n, described n is more than or equal to 2 integer.Also, in the present embodiment, the m=2 in embodiment mono-, but should be understood that, herein just for the present invention being done to schematic explanation, be only terminal A but the present invention also is not only confined to control base station _itwo carrier waves are provided, and also, the value of a kind of m of embodiment can be taken as any integer value that is greater than 2.

In order to ensure to control base station to terminal A _i(wherein, i=1 ..., n, described n is more than or equal to 2 integer) and two carrier information times of advent sending poorly meet TAE requirement, the Timing Advance carrier wave transmitting time of large (propagation delay time is larger) need to shift to an earlier date.Because different terminals in control Serving cell, base station is for carrier wave C ₁with carrier wave C ₂up transmitting time lead TA _i1, TA _i2can be different apart from factors such as base station locations because of it, i.e. TA _i1≠ TA _i2thereby, therefore need to consider the up transmitting time lead of different terminals on carrier wave C1 and carrier wave C2 and determine the carrier wave transmitting time of base station for different carrier.In the present embodiment, establish carrier wave C ₁transmitting time be T1, establish carrier wave C ₂transmitting time be T2; Shown in Figure 3, the setting up procedure of carrier wave C1 and carrier wave C2 transmitting time is specific as follows:

Step 301: obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Step 302: from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, select C ₁as reference carrier, be also TA _i1for lead fiducial time;

Step 303: by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (1-2)}, wherein, j and k are unequal;

Step 304: the lead difference DELTA TA based on obtaining _{i (1-2)}obtain the class mean value Δ T of Timing Advance difference _(1-2); Also, by Δ TA _{1 (1-2)}..., Δ TA _{n (1-2)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(1-2);

Step 305: the class mean value Δ T of the Timing Advance difference based on obtaining _(1-2)carrier wave C is set ₁, C ₂transmitting time, specific as follows:

Judge Δ T _(1-2)whether be more than or equal to 0, in this way, obtain T ₂=T ₁+ Δ T _(1-2); Otherwise, T ₂=T ₁-Δ T _(1-2)in the present embodiment, specifically can be by T ₁be made as for zero moment.

It should be noted that in above-mentioned steps 305, also can comprise the following steps:

Δ T based on obtaining _(1-2)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

Embodiment tri-:

In the present embodiment, establish relay base station and adopt wireless mode to be connected with control base station (Donor eNode B), this link can be described as return link (Backhaul Link); Relay base station adopts with the similar mode in control base station and is connected with each terminal, is called access link (Access Link).In the MTA carrier aggregation scene that 3GPP RAN2 specifies, control base station and relay base station and can adopt different carrier waves (for example C ₁and C ₂) for terminal provides service, control base station and adopt carrier wave C ₁for terminal provides service; In this simultaneously, the service employing carrier wave C that control base station provides for terminal for relay base station, relay base station ₂.C ₁and C ₂may be same frequency band intercarrier, at this moment both can be considered as being with intercarrier polymerization; C ₁and C ₂also may be the carrier wave of different frequency bands, at this moment both can be considered as interband carrier aggregation., all may there is C in above-mentioned situation ₁and C ₂the incoming terminal time difference, (TAE) was larger, and need to adopt different up lead TA.The present embodiment for this application scenarios for carrier wave C ₁with carrier wave C ₂the setting up procedure of transmitting time describe, shown in Figure 4:

Step 401: obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically also can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij, for example, control base station and can pass through terminal A _iat carrier wave C ₁send the mode acquisition time lead TA of random joining procedure _i1; Relay base station can be passed through terminal A _iat carrier wave C ₂send the mode acquisition time lead TA of random joining procedure _i2, and send to and control base station by above-mentioned return link; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Step 402: from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, selecting C2 as reference carrier, is also TA _i2for lead fiducial time;

Step 403: by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (2-1)}, wherein, j and k are unequal;

Step 404: obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz;

Step 405: the lead difference DELTA TA based on obtaining _{i (1-2)}obtain the class mean value Δ T of Timing Advance difference in conjunction with this application scenarios _(2-1); Also, by Δ TA _{1 (2-1)}..., Δ TA _{n (2-1)}and described TT _1z..., TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(2-1);

Step 406: the class mean value Δ T of the Timing Advance difference based on obtaining _(2-1)carrier wave C is set ₁, C ₂transmitting time, specific as follows:

Judge Δ T _(2-1)whether be more than or equal to 0, in this way, obtain T ₁=T ₂+ Δ T _(2-1); Otherwise, T ₁=T ₂-Δ T _(2-1)in the present embodiment, specifically can be by T ₂be made as for zero moment.

It should be noted that in above-mentioned steps 406, also can comprise the following steps:

Δ T based on obtaining _(2-1)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

It should be noted that, in the present embodiment, be only that as example, the present invention will be described taking a relay base station, but the present invention is not limited in the situation of a relay base station, known according to the scheme in above-described embodiment one, those skilled in the art are easy to be generalized to the situation of multiple relay base station according to record herein, no longer repeat herein.

Embodiment tetra-:

In the present embodiment, establish RRH and adopt optical fiber to be connected with control base station (Donor eNode B), be referred to as return link; If adopting with the similar mode in control base station, RRH is connected with each terminal.In the MTA carrier aggregation scene that 3GPP RAN2 specifies, control base station and RRH and can adopt different carrier waves (for example C ₁and C ₂) for terminal provides service, base station adopts carrier wave C ₁for terminal provides service, and the service employing carrier wave C that RRH provides for terminal ₂.C ₁, C ₂may be same frequency band intercarrier, at this moment both can be considered as being with intercarrier polymerization; C ₁, C ₂also may be the carrier wave of different frequency bands, at this moment both can be considered as interband carrier aggregation., all may there is C in above-mentioned two situations ₁and C ₂the incoming terminal time difference, (TAE) was larger, and need to adopt different up leads (TA).The present embodiment is for the carrier wave C of this application scenarios ₁with carrier wave C ₂the setting up procedure of transmitting time describe, shown in Figure 5:

Step 501: obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically also can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij, for example, control base station and can pass through terminal A _iat carrier wave C ₁send the mode acquisition time lead TA of random joining procedure _i1; RRH can pass through terminal A _iat carrier wave C ₂send the mode acquisition time lead TA of random joining procedure _i2, and send to and control base station by above-mentioned return link; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Step 502: from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, select C ₂as reference carrier, be also TA _i2for lead fiducial time;

Step 503: by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (2-1)}, wherein, j and k are unequal;

Step 504: obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir;

Step 505: the lead difference DELTA TA based on obtaining _{i (1-2)}obtain the class mean value Δ T of Timing Advance difference in conjunction with this application scenarios _(2-1); Also, by Δ TA _{1 (2-1)}..., Δ TA _{n (2-1)}and described TT _ir..., TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(2-1);

Step 506: the class mean value Δ T of the Timing Advance difference based on obtaining _(2-1)carrier wave C is set ₁, C ₂transmitting time, specific as follows:

Judge Δ T _(2-1)whether be more than or equal to 0, in this way, obtain T ₁=T ₂+ Δ T _(2-1); Otherwise, T ₁=T ₂-Δ T _(2-1)in the present embodiment, specifically can be by T ₂be made as for zero moment.

It should be noted that in above-mentioned steps 506, also can comprise the following steps:

Δ T based on obtaining _(2-1)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

Set each carrier wave C by said process ₁..., C _mtransmitting time after, transmitting time that can be based on setting is at carrier wave C ₁..., C _min at least one carrier wave on send corresponding signal of communication and communicate.

It should be noted that, in the present embodiment, be only that as example, the present invention will be described taking a RRH, but the present invention is not limited in the situation of a RRH, known according to the scheme in above-described embodiment one, those skilled in the art are easy to be generalized to the situation of multiple RRH according to record herein, no longer repeat herein.

Embodiment five:

For a better understanding of the present invention, the present embodiment is described further the application in conjunction with communication system.

Communication system in the present embodiment comprises the terminal A controlling in base station and community _i, i=1 ..., n, n is more than or equal to 2 integer;

Shown in Figure 6, the control base station in the present embodiment comprises that Timing Advance acquisition module, reference carrier selection module, Timing Advance difference acquisition module and carrier wave transmitting time arrange module;

Timing Advance acquisition module is for obtaining in the manner described above terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; J=1 ..., m, m is more than or equal to 2 integer;

Reference carrier selects module to be used for from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

Timing Advance difference acquisition module is used for TA _ijwith TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, j and k are unequal;

Carrier wave transmitting time arranges module for based on Timing Advance difference DELTA TA _{i (k-j)}carrier wave C is set ₁..., C _mtransmitting time, specific as follows:

Carrier wave transmitting time arranges the lead difference DELTA TA of module based on obtaining _{i (k-j)}obtain the class mean value Δ T of Timing Advance difference in conjunction with concrete application scenarios _(k-j);

Carrier wave transmitting time arranges the class mean value Δ T of the Timing Advance difference of module based on obtaining _(k-j)carrier wave C is set ₁..., C _mtransmitting time, specific as follows:

Reference carrier C is set _ktransmitting time T _k;

Judge the class mean value Δ T of Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).

Be example in conjunction with three kinds of application scenarioss in said system and embodiment bis-to embodiment tetra-respectively below, the present invention will be further described:

Embodiment six:

In the present embodiment, control two component carrier C of base station employing carrier aggregation ₁and C ₂for terminal A _iservice, wherein, i=1 ..., n, described n is more than or equal to 2 integer.Also, in the present embodiment, the m=2 in embodiment mono-, but should be understood that, herein just for the present invention being done to schematic explanation, be only terminal A but the present invention also is not only confined to control base station _itwo carrier waves are provided, and also, the value of a kind of m of embodiment can be taken as any integer value that is greater than 2.

In order to ensure to control base station to terminal A _i(wherein, i=1 ..., n, described n is more than or equal to 2 integer) and two carrier information times of advent sending poorly meet TAE requirement, the Timing Advance carrier wave transmitting time of large (propagation delay time is larger) need to shift to an earlier date.Because different terminals in control Serving cell, base station is for carrier wave C ₁with carrier wave C ₂up transmitting time lead TA _i1, TA _i2can be different apart from factors such as base station locations because of it, i.e. TA _i1≠ TA _i2thereby, therefore need to consider the up transmitting time lead of different terminals on carrier wave C1 and carrier wave C2 and determine the carrier wave transmitting time of base station for different carrier.In the present embodiment, establish carrier wave C ₁transmitting time be T1, establish carrier wave C ₂transmitting time be T2; The setting up procedure of carrier wave C1 and carrier wave C2 transmitting time is specific as follows:

Timing Advance acquisition module obtains terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Reference carrier selects module from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, select C ₁as reference carrier, be also TA _i1for lead fiducial time;

Timing Advance difference acquisition module is by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (1-2)}, wherein, j and k are unequal;

Carrier wave transmitting time arranges the lead difference DELTA TA of module based on obtaining _{i (1-2)}obtain the class mean value Δ T of Timing Advance difference _(1-2); Also, by Δ TA _{1 (1-2)}..., Δ TA _{n (1-2)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(1-2);

Carrier wave transmitting time arranges the class mean value Δ T of the Timing Advance difference of module based on obtaining _(1-2)carrier wave C is set ₁, C ₂transmitting time, specific as follows:

Carrier wave transmitting time arranges module and judges Δ T _(1-2)whether be more than or equal to 0, in this way, obtain T ₂=T ₁+ Δ T _(1-2); Otherwise, T ₂=T ₁-Δ T _(1-2)in the present embodiment, specifically can be by T ₁be made as for zero moment.

It should be noted that in said process, carrier wave transmitting time arranges the Δ T that module also can be based on obtaining _(1-2)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

Embodiment seven:

In the present embodiment, establish relay base station and adopt wireless mode to be connected with control base station (Donor eNode B), this link can be described as return link (Backhaul Link); Relay base station adopts with the similar mode in control base station and is connected with each terminal, is called access link (Access Link).In the MTA carrier aggregation scene that 3GPP RAN2 specifies, control base station and relay base station and can adopt different carrier waves (for example C ₁and C ₂) for terminal provides service, control base station and adopt carrier wave C ₁for terminal provides service; In this simultaneously, the service employing carrier wave C that control base station provides for terminal for relay base station, relay base station ₂.C ₁and C ₂may be same frequency band intercarrier, at this moment both can be considered as being with intercarrier polymerization; C ₁and C ₂also may be the carrier wave of different frequency bands, at this moment both can be considered as interband carrier aggregation., all may there is C in above-mentioned situation ₁and C ₂the incoming terminal time difference, (TAE) was larger, and need to adopt different up lead TA.The present embodiment for this application scenarios for carrier wave C ₁with carrier wave C ₂the setting up procedure of transmitting time describe:

Timing Advance acquisition module obtains terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically also can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij, for example, control base station and can pass through terminal A _iat carrier wave C ₁send the mode acquisition time lead TA of random joining procedure _i1; Relay base station can be passed through terminal A _iat carrier wave C ₂send the mode acquisition time lead TA of random joining procedure _i2, and send to the Timing Advance acquisition module of controlling base station by above-mentioned return link; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Reference carrier selects module from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, selecting C2 as reference carrier, is also TA _i2for lead fiducial time;

Timing Advance difference acquisition module is by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (2-1)}, wherein, j and k are unequal;

Carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz; By Δ TA _{1 (2-1)}..., Δ TA _{n (2-1)}and described TT _1z..., TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(2-1), specific as follows:

Carrier wave transmitting time arranges module and judges Δ T _(2-1)whether be more than or equal to 0, in this way, obtain T ₁=T ₂+ Δ T _(2-1); Otherwise, T ₁=T ₂-Δ T _(2-1)in the present embodiment, specifically can be by T ₂be made as for zero moment.

It should be noted that in said process, carrier wave transmitting time arranges the Δ T that module also can be based on obtaining _(2-1)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

Embodiment eight:

In the present embodiment, establish RRH and adopt optical fiber to be connected with control base station (Donor eNode B), be referred to as return link; If adopting with the similar mode in control base station, RRH is connected with each terminal.In the MTA carrier aggregation scene that 3GPP RAN2 specifies, control base station and RRH and can adopt different carrier waves (for example C ₁and C ₂) for terminal provides service, base station adopts carrier wave C ₁for terminal provides service, and the service employing carrier wave C that RRH provides for terminal ₂.C ₁, C ₂may be same frequency band intercarrier, at this moment both can be considered as being with intercarrier polymerization; C ₁, C ₂also may be the carrier wave of different frequency bands, at this moment both can be considered as interband carrier aggregation., all may there is C in above-mentioned two situations ₁and C ₂the incoming terminal time difference, (TAE) was larger, and need to adopt different up leads (TA).The present embodiment is for the carrier wave C of this application scenarios ₁with carrier wave C ₂the setting up procedure of transmitting time describe:

Timing Advance acquisition module obtains terminal A in community _iat carrier wave C _jon Timing Advance TA _ij, specifically also can pass through terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij, for example, control base station and can pass through terminal A _iat carrier wave C ₁send the mode acquisition time lead TA of random joining procedure _i1; RRH can pass through terminal A _iat carrier wave C ₂send the mode acquisition time lead TA of random joining procedure _i2, and send to the Timing Advance acquisition module of controlling base station by above-mentioned return link; Wherein, described i=1 ..., n, n is more than or equal to 2 integer; Described j=1 ..., m, described m=2;

Reference carrier selects module from carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, terminal A _iat carrier wave C _kon Timing Advance TA _ikfor lead fiducial time; In the present embodiment, select C ₂as reference carrier, be also TA _i2for lead fiducial time;

Timing Advance difference acquisition module is by the TA of institute _i2with TA _i1subtract each other, obtain Timing Advance difference DELTA TA _{i (2-1)}, wherein, j and k are unequal;

Carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir, by Δ TA _{1 (2-1)}..., Δ TA _{n (2-1)}and described TT _ir..., TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(2-1); The class mean value Δ T of the Timing Advance difference based on obtaining _(2-1)carrier wave C is set ₁, C ₂transmitting time, specific as follows:

Carrier wave transmitting time arranges module and judges Δ T _(2-1)whether be more than or equal to 0, in this way, obtain T ₁=T ₂+ Δ T _(2-1); Otherwise, T ₁=T ₂-Δ T _(2-1)in the present embodiment, specifically can be by T ₂be made as for zero moment.

It should be noted that in said process, carrier wave transmitting time arranges the Δ T that module also can be based on obtaining _(2-1)judge terminal A ₁..., A _nin whether exist do not meet TAE require terminal; As still have, control base station and abandon these terminals to adopt carrier aggregation technology, adopt single carriers to carry out transfer of data for these terminals, adopt carrier wave that link-quality is good for this reason Terminal Type carry out transfer of data.Then this Terminal Type is got rid of in the sequence of calculating delivery time.

Set each carrier wave C by said process ₁..., C _mtransmitting time after, transmitting time that can be based on setting is at carrier wave C ₁..., C _min at least one carrier wave on send corresponding signal of communication and communicate.

Visible, according to each terminal, the Timing Advance on each carrier wave calculates respectively the time sequence information that base station sends for each carrier wave in the present invention, and according to this time sequence information, taking one of them component carrier as benchmark, calculate other component carriers Timing Advance time difference with it, and then the Timing Advance on different carrier is determined the transmitting time of each carrier wave according to different terminals, to ensure that the maximum time difference between each carrier signal that in community, all terminals receive meets requirement and the corresponding demodulation performance of TAE.

Above content is in conjunction with concrete execution mode further description made for the present invention, can not assert that specific embodiment of the invention is confined to these explanations.For general technical staff of the technical field of the invention, without departing from the inventive concept of the premise, can also make some simple deduction or replace, all should be considered as belonging to protection scope of the present invention.

Claims (12)

1. a carrier wave transmitting time method to set up, is characterized in that comprising:

Obtain terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; Described i=1 ..., n, described n is more than or equal to 2 integer; Described j=1 ..., m, described m is more than or equal to 2 integer;

From described carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, described terminal A _iat described carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

By described TA _ijwith described TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, described j is not equal to described k;

Based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time.

2. carrier wave transmitting time method to set up as claimed in claim 1, is characterized in that, described carrier wave C _jbe described terminal A for controlling base station _ithe carrier wave providing; Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

By Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)described carrier wave C is set ₁..., C _mtransmitting time.

3. carrier wave transmitting time method to set up as claimed in claim 1, is characterized in that, described m=2, described carrier wave C ₁be described terminal A for controlling base station _ithe carrier wave providing, described carrier wave C ₂for relay base station is described terminal A _ithe carrier wave providing;

Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz;

By described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1z, TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

4. carrier wave transmitting time method to set up as claimed in claim 1, is characterized in that, described m=2, described carrier wave C ₁be described terminal A for controlling base station _ithe carrier wave providing, described carrier wave C ₂for RF remote is described terminal A _ithe carrier wave providing;

Described based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Obtain terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir;

By described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1r, TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

5. the carrier wave transmitting time method to set up as described in claim 1-4 any one, is characterized in that, described in obtain the terminal A in community, place, base station _iat carrier wave C _jon Timing Advance TA _ijbe specially:

By terminal A _iat carrier wave C _jsend the mode acquisition time lead TA of random joining procedure _ij.

6. the carrier wave transmitting time method to set up as described in claim 2-4 any one, is characterized in that, the described class mean value Δ T based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time comprise:

Reference carrier C is set _ktransmitting time T _k;

Judge the class mean value Δ T of described Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).

7. the carrier wave transmitting time method to set up as described in claim 1-4 any one, is characterized in that, described carrier wave C _jfor the different carrier with in interior continuous carrier polymerization, or the different carrier in discontinuous carrier polymerization in band, or different carrier in the polymerization of interband continuous carrier.

8. a communication system, is characterized in that comprising the terminal A controlling in base station and community _i; Described i=1 ..., n, described n is more than or equal to 2 integer; Described control base station comprises that Timing Advance acquisition module, reference carrier selection module, Timing Advance difference acquisition module and carrier wave transmitting time arrange module,

Described Timing Advance acquisition module is used for obtaining terminal A in community _iat carrier wave C _jon Timing Advance TA _ij; Described j=1 ..., m, described m is more than or equal to 2 integer;

Described reference carrier selects module to be used for from described carrier wave C ₁..., C _mcarrier wave C of middle selection _kas reference carrier, described terminal A _iat described carrier wave C _kon Timing Advance TA _ikfor lead fiducial time;

Described Timing Advance difference acquisition module is used for described TA _ijwith described TA _iksubtract each other, obtain Timing Advance difference DELTA TA _{i (k-j)}, described j is not equal to described k;

Carrier wave transmitting time arranges module for based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time.

9. communication system as claimed in claim 8, is characterized in that, described carrier wave C _jfor described control base station is described terminal A _ithe carrier wave providing; Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module by Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}the value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)described carrier wave C is set ₁..., C _mtransmitting time.

10. communication system as claimed in claim 8, is characterized in that, described m=2, described carrier wave C ₁for described control base station is described terminal A _ithe carrier wave providing, described carrier wave C ₂for relay base station is described terminal A _ithe carrier wave providing;

Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _iz;

Described carrier wave transmitting time arranges module by described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1z, TT _nzthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

11. communication systems as claimed in claim 8, is characterized in that, described m=2, described carrier wave C ₁for described control base station is described terminal A _ithe carrier wave providing, described carrier wave C ₂for RF remote is described terminal A _ithe carrier wave providing;

Described carrier wave transmitting time arranges module based on described Timing Advance difference DELTA TA _{i (k-j)}described carrier wave C is set ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module and obtains terminal A _ithe corresponding downlink transfer time T T of base station to relay base station that control _ir;

Described carrier wave transmitting time arranges module by described Δ TA _{1 (k-j)}..., Δ TA _{n (k-j)}, and described TT _1r, TT _nrthe value that addition obtains obtains the class mean value Δ T of Timing Advance difference divided by n _(k-j);

Described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time.

12. communication systems as described in claim 9-11 any one, is characterized in that, described carrier wave transmitting time arranges the class mean value Δ T of module based on described Timing Advance difference _(k-j)value arranges described carrier wave C ₁..., C _mtransmitting time comprise:

Described carrier wave transmitting time arranges module reference carrier C is set _ktransmitting time T _k;

Described carrier wave transmitting time arranges module and judges the class mean value Δ T of described Timing Advance difference _(k-j)whether be more than or equal to 0, in this way, carrier wave C _jtransmitting time T _j=T _k+ Δ T _(k-j); Otherwise, carrier wave C _jtransmitting time T _j=T _k-Δ T _(k-j).