Background technology
Long Term Evolution (LTE, Long Term Evolution) project is the evolution of 3G, and it improves and strengthened the aerial access technology of 3G.Adopt OFDM (OFDM, Orthogonal Frequency Division Multiplexing) and MIMO (multiple-input and multiple-output, Multiple-Input Multiple-Out-put) sole criterion as its wireless network evolution.The peak rate of descending 100Mbit/s and up 50Mbit/s can be provided under the 20MHz spectral bandwidth.Improve the performance of Cell Edge User, improved cell capacity, and reduced system delay.
In Rel 11, multi-point cooperative (CoMP, Cordinated multi-point) is a kind of MIMO technology, through the cooperation of a plurality of signal launch points, with being originally that interference signals becomes the signal that can help to improve performance.
There is common part in CoMP as the branch and the other types usage of MIMO technology, but because the difference of working method also has unique consideration point.
The power division problem: in traditional M IMO system, because each antenna is all located placement in the base station, so their transmitting power is limited by total base station power.And for CoMP, the Power Limitation at possible each eNB/RRH place is all different, therefore can cause different optimization conclusions.For example, whether the constant power designed code book is suitable.
Complexity issue: because CoMP is a plurality of geographical eNB/RRH/antenna fellowships that separate; Therefore to consider the whole users' under the covering of a plurality of sub-districts performance optimization problem; Processing complexity becomes non-linear growth; Therefore corresponding to user's scheduling, various aspects such as channel estimating are all had higher requirement.
Delay problem: for traditional colocation site mimo system; Basically exceed consider signal inside of base station propagation delay time; But for the CoMP system; Because need in the cooperation of different location set eNB, transmit data/dispatch, excessive propagation delay time will make the performance gain of CoMP be restricted, the signaling transmission system of this point during to networking proposed requirement.
The terminal mainly is based on CSI-RS to the measurement of channel information; The possible position of CSI-RS in the LTE frame structure for the different antennae port number; Add that the cycle information that these positions possibly occur constitutes a CSI-RS resource distribution, the base station is notified its that which prepares to select dispose for each UE with high-level signaling to supply the terminal to carry out channel measurement.The CSI-RS reference symbol transmitting site and the cycle of this sub-district arranged in the base station, and through high-level signaling configuring condition sent to corresponding terminal, and corresponding terminal is according to the go forward side by side channel estimating of line correlation of corresponding configuration location CSI-RS reference symbol.Disposing the different cycles can corresponding different channel variation speed; The port that each cell configuration is different can manage to avoid interference each other; And can cut off the transmission of the antenna port that the generation of other sub-districts is disturbed, thereby reach the purpose of better measured channel.
For this working method, in the former working version, owing to only consider the situation of this transmitting antenna port in sub-district, number of users is also more limited in the sub-district of facing, and than being easier to the user is classified to come definite cycle that occurs.But under the mode of operation of CoMP, signal launch point will be towards all users in the collaboration region, and a user will measure the whole signal launch points in the collaboration region, the channel measurement burden that causes thus.The user of fast change of channel is for example arranged in a sub-district, disposed the CSI-RS in 5ms cycle, and other signal launch points all are users at a slow speed; All disposed the CSI-RS cycle of 80ms, and under the CoMP pattern, because this user need measure the channel of all signal launch points; Therefore all signal launch points all need dispose the CSI-RS in 5ms cycle; And simultaneously because the number that needs the measuring-signal launch point under the CoMP pattern also than original many, is for example measured 3 neighbor cells simultaneously, there are 3 sectors each sub-district; Distribution 5-6 high power/low-power RRH and Microcell under each sector, the signal launch point number progression that will cause needs to be measured increases.
Channel measurement need be carried out to the signal launch point in the CoMP collaboration region in the terminal in the time of work; Because signal launch point number is numerous; The antenna port number of each signal launch point also maybe be more; And the CSI-RS resource-constrained of system need guarantee the ageing signal launch point existence certain difficulty all with covering simultaneously.
In sum, under the existing C oMP mode of operation, exist the CSI-RS resource nervous, and because CSI-RS is a resource of having utilized PDSCH, the CSI-RS that high density distributes has also caused the decline of PDSCH utilance simultaneously.
Summary of the invention
The invention provides the channel measuring method of a kind of LTE system,, improve the resource utilization of PDSCH with the nervous problem of CSI-RS resource under the existing CoMP pattern that solves.
The invention discloses the channel measuring method of a kind of LTE system, this method is applicable to that this method comprises under multipoint cooperative CoMP mode of operation:
The base station is that a signal launch point among the CoMP marks off a reference symbol put area in Physical Downlink Shared Channel PDSCH, in said reference symbol put area, a plurality of reference symbols is set;
In said reference symbol put area, the base station is that each signal launch point is set a resources pattern that has sign among the said CoMP; The resources pattern and the positional information of said reference symbol put area in PDSCH of each signal launch point are sent to the terminal;
The terminal utilizes the reference symbol on the said reference symbol put area that each signal launch point is carried out channel measurement according to the positional information of reference symbol put area in PDSCH;
The terminal is chosen and is satisfied pre-conditioned resources pattern according to the channel measurement result of each signal launch point, gives the base station with the identification feedback of selected resources pattern;
Corresponding signal launch point is searched according to the sign of the resources pattern of terminal feedback in the base station, on said signal launch point, uses channel condition information measurement pilot frequency CSI-RS resource to carry out channel measurement.
In said method, said reference symbol put area discrete distribution on the frequency domain of whole PDSCH is perhaps concentrated to distribute on the frequency domain of part PDSCH;
Wherein, said reference symbol put area comprises one or more basic mapping blocks, and basic mapping block is made up of all or part of resource RE of one or more Physical Resource Block PRB.
In said method, said base station is that a signal launch point among the CoMP marks off a reference symbol put area and comprises in PDSCH:
When adjacent base station sends the PDSCH of same frequency,
The reference symbol put area that the base station is divided is arranged in the common factor of the idle PDSCH of each base station, CoMP collaboration region;
Perhaps, the transfer of data of mapping area is at first arranged in the base station, arranges the transfer of data of PDSCH again.
In said method, said base station is that resources pattern that has sign of each signal launch point setting comprises among the said CoMP:
In said reference symbol put area, the number of the corresponding RE of each signal launch point is identical; Wherein,
A RE in the corresponding said mapping area of signal launch point;
Perhaps, a plurality of RE in the corresponding said mapping area of signal launch point;
Perhaps, a plurality of RE in the corresponding said mapping area of a plurality of signal launch points distinguish through specific coded system between the various signals launch point.
In said method, in said reference symbol put area, exist not under the situation of the RE that is taken by any signal launch point, said RE is used to measure the interference that the signal launch point outside the CoMP collaboration region causes signal launch point in the CoMP collaboration region;
Perhaps,
In said reference symbol put area, exist under the situation that is used for the special-purpose RE of certain allocated resource configuration mode, said RE is used to measure the interference that the signal launch point outside the CoMP collaboration region causes signal launch point in the CoMP collaboration region.
In said method, said resources pattern and the positional information of said reference symbol put area in PDSCH with each signal launch point sends to the terminal and comprises:
The resources pattern and the positional information of said reference symbol put area in PDSCH of each signal launch point are sent to the terminal through physical downlink control channel PDCCH or high-level signaling;
Perhaps, parameter and the positional information of said reference symbol put area in PDSCH with the resources pattern of each signal launch point sends to the terminal through PDCCH or high-level signaling.
In said method, saidly send to the terminal through PDCCH or high-level signaling and comprise:
In said PDCCH or high-level signaling, use the said reference symbol put area of specific bit group-indicate.
In said method, said choosing satisfied pre-conditioned resources pattern and comprised:
The terminal is according to the data that on the corresponding RE of each resources pattern, receive, calculate each resources pattern the signal to noise ratio on the corresponding RE, choose wherein signal to noise ratio greater than the resources pattern of designated value, and to the sign of these resources pattern of base station feedback.
In said method, said base station is that resources pattern that has sign of each signal launch point setting comprises among the said CoMP:
After the long-time data statistics of said base station basis; Be lower than the threshold level at any terminal under the said base station when the channel quality that has the pairing a plurality of signal launch points of different resource configuration mode; And when the set of the Serving cell that the terminal of said a plurality of signal launch points is connected does not respectively overlap
A plurality of signal launch points that said channel quality is lower than the threshold level at any terminal under the said base station use identical resources pattern.
In said method, a plurality of signal launch points that said channel quality is lower than the threshold level at any terminal under the said base station use identical resources pattern to comprise:
When said terminal during to the unlike signal launch point of the said use same asset of base station feedback configuration mode,
Distinguish the various signals launch point according to the pairing different service cells in each terminal.
In sum; The present invention is through divide the reference symbol put area freely in the PDSCH zone; The RE that the reference symbol put area occupies can set according to actual conditions, in a sub-frame, holds the target that the signal launch point of more number is more measured thereby reach; When dividing this piece reference symbol put area, can consider the actual conditions of business datum flexibly in addition, reduce influence business.And the correspondence one by one through launch point and resources pattern has reduced system's configuration information needed transmission capacity through the means such as configuration that adopt identical RE number, has also reduced the terminal information feedback quantity simultaneously.
Embodiment
For making the object of the invention, technical scheme and advantage clearer, will combine accompanying drawing that embodiment of the present invention is done to describe in detail further below.
The invention discloses channel measuring method in a kind of LTE system, this method is applicable to the mode of operation at multipoint cooperative CoMP.Fig. 1 is the flow chart of channel measuring method in a kind of LTE system among the present invention; It is as shown in Figure 1,
Step 101, base station are that a signal launch point among the CoMP marks off a reference symbol put area in Physical Downlink Shared Channel PDSCH, in said reference symbol put area, a plurality of reference symbols are set.
Step 102, in said reference symbol put area, the base station is that each signal launch point is set a resources pattern that has sign among the said CoMP; The resources pattern and the positional information of said reference symbol put area in PDSCH of each signal launch point are sent to the terminal.
Step 103, terminal utilize the reference symbol on the said reference symbol put area that each signal launch point is carried out channel measurement according to the positional information of reference symbol put area in PDSCH.
Step 104, terminal are chosen and are satisfied pre-conditioned resources pattern according to the channel measurement result of each signal launch point, give the base station with the identification feedback of selected resources pattern.
Step 105, base station are searched corresponding signal launch point according to the sign of the resources pattern of terminal feedback, on said signal launch point, use channel condition information measurement pilot frequency CSI-RS resource to carry out channel measurement.
In flow chart as shown in Figure 1; In step 101; The base station is that a signal launch point in the CoMP collaboration region marks off a reference symbol put area in PDSCH, is specially: the base station marks off appropriate area symbol put area as a reference according to the number and the actual conditions of signal launch point in the affiliated CoMP collaboration region in the PDSCH of free time; Wherein, Said reference symbol put area comprises one or more basic mapping block, and basic mapping block is made up of all or part of RE of one or more PRB, and the channel situation that the base station is measured is according to actual needs chosen the number of basic mapping block.Said reference symbol put area can be on the frequency domain of whole PDSCH discrete distribution, perhaps can on the frequency domain of part PDSCH, concentrate distribution.
In the said reference symbol put area a plurality of reference symbols are set; Be specially: in the basic mapping block in said reference symbol put area; To the different resources configuration mode; On corresponding RE, place reference symbol, said reference symbol is used to measure the channel quality of unlike signal launch point.
Fig. 2 is the structural representation of a kind of basic mapping block among the present invention; In this embodiment, said basic mapping block is made up of the frequency domain width of a PRB and the corresponding time domain width that marks off; As shown in Figure 2, the base station with idle data subcarrier in the said basic mapping block from time domain to the frequency domain number consecutively, obtain corresponding No. 0 RE~No. 119 RE totally 120 RE resources.
In said reference symbol put area, the base station is that all the signal launch points among the said CoMP are set unique resources pattern.Wherein, said resources pattern is specially: the one-to-one relationship in signal launch point and the said basic mapping block between the idle RE.Wherein, said resources pattern has unique sign.In an embodiment of the present invention, the resources pattern that the signal launch point is corresponding unique, the sign of said resources pattern can be carried out number consecutively through the RE of correspondence.
In said reference symbol put area, the number of the corresponding subcarrier of each signal launch point is identical; Wherein, a RE in the corresponding said mapping area of signal launch point; Perhaps, a plurality of RE in the corresponding said mapping area of signal launch point; Perhaps, a plurality of RE in the corresponding said mapping area of a plurality of signal launch points distinguish through specific coded system between the various signals launch point.
In an embodiment of the present invention, a signal launch point is through the corresponding RE of different resources configuration mode, the different RE that the various signals launch point is corresponding.Through the 1st resources pattern, corresponding No. 0 RE shines upon successively like the 1st signal launch point, and the n-signal launch point is through N resource distribution module, corresponding n-1 RE.
In another embodiment of the invention, two number of sub-carrier that the signal launch point is corresponding adjacent; Pass through the 1st resources pattern like the 1st signal launch point, corresponding No. 0 and No. 1 RE; The 2nd signal launch point passes through the 2nd resources pattern, corresponding No. 2 and 3 work song carrier waves; Shine upon successively, the n-signal launch point passes through N resource distribution module, corresponding 2*n-2 number and 2*n-1 work song carrier wave.
In other a kind of embodiment of the present invention; Two two subcarriers that the signal launch point is corresponding adjacent, and use the mode of orthogonal coding to distinguish the different resources configuration mode, wherein; The configuration of the corresponding low sequence number of use+1+1, the configuration of the corresponding high sequence number of use+1-1.Pass through corresponding 0 work song carrier wave of the 1st resources pattern and 1 work song carrier wave like the 1st signal launch point; The 2nd signal launch point is through corresponding 0 work song carrier wave of the 2nd resources pattern and 1 work song carrier wave; Wherein+and corresponding the 1st resources pattern of 1+1, corresponding the 2nd resources pattern of+1-1.Receiving terminal can independently recover the signal of each launch point with the quadrature merging mode of correspondence.Data on the RE of various resources pattern correspondences should be separated through time-division/frequency division/sign indicating number grading mode be used for channel measurement.
The base station is that each signal launch point is set unique resources pattern among the said CoMP; The resources pattern and the positional information of said reference symbol put area in PDSCH of each signal launch point are sent to the terminal, perhaps can the parameter and the positional information of said reference symbol put area in PDSCH of the resources pattern of each signal launch point be sent to the terminal.Wherein, can send to the terminal through PDCCH or high-level signaling.
In an embodiment of the present invention, be example with basic mapping block shown in Figure 2,50 signal launch points are arranged among the CoMP, per 2 the adjacent RE of base station sets are a resources pattern, corresponding signal launch point.Promptly the 1st signal launch point is through No. 0 RE and No. 1 RE in the corresponding basic mapping block of the 1st resources pattern; The 2nd signal launch point is through No. 2 RE and No. 3 RE in the corresponding basic mapping block of the 2nd resources pattern; N signal launch point is through 2n-1 RE and 2n RE in the corresponding basic mapping block of n resources pattern; The 50th signal launch point is through No. 99 RE and No. 100 RE in the corresponding basic mapping block of the 50th resources pattern; The maximum of n is the total number of signal launch point, and the minimum value of n is 1.In addition, pairing 2m-1 RE of m resources pattern and 2m RE, 50<m≤60 are used to measure the interference that the extra-regional signal launch point of CoMP causes the signal launch point in the CoMP zone.
When the base station sends to the terminal with said resources pattern, can only send the parameter 2 of said resources pattern; The RE numbering that each resources pattern is shared is known according to the parameter 2 of said resources pattern in the terminal.Operation can be saved the volume of transmitted data of corresponding PDCCH or high-level signaling like this.
The channel quality of various signals launch point is measured according to said resources pattern in the terminal on different RE, as tests corresponding signal to noise ratio.
According to the measurement result of carrying out through the different resource configuration mode behind the channel measurement; Through after the long data statistics; Choose successively and satisfy pre-conditioned resources pattern; As according to the pairing successively from high to low resources pattern of signal to noise ratio, give the base station with the identification feedback of selected resources pattern.The base station can get access to the respective signal launch point according to the sign of said resources pattern.
The base station sends to the terminal with the resources pattern of each signal launch point or its parameter and the positional information of said reference symbol put area in PDSCH through PDCCH.In an embodiment of the present invention, the base station is through being provided with a specific Radio Network Temporary Identifier RNTI, and the corresponding virtual terminal of said RNTI is used in reference to the positional information that is shown in the reference symbol put area that marks off in the PDSCH clear area; On the Downlink Control Information DCI that carries, select a specific bit group to be used to indicate the purposes of said reference symbol put area above that.All terminals in this CoMP zone can obtain the positional information that corresponding PDSCH goes up resources pattern through intercepting this DCI information, and in said DCI, place the parameter information of said resources pattern.
Fig. 3 is the sketch map that uses PDCCH indication reference symbol put area among the present invention, and is as shown in Figure 3, virtual terminal of base station sets; In PDCCH; Through the pairing DCI message of said virtual terminal; Indicate the positional information of the reference symbol put area that said virtual terminal divides on PDSCH, and the said reference symbol put area that marks off of indication is used to place that each signal launch point carries out the required reference symbol of channel measurement in the CoMP collaboration region on certain specific bit position of said DCI.
Each terminal obtains the resources pattern and the positional information of said reference symbol put area in PDSCH of each signal launch point through intercepting specific RNTI corresponding virtual terminal among this PDCCH among the DCI that is carried.
Because the symbolic number of PDCCH can change, and the number of signal launch point maybe be less than the idle sub-carrier number in the basic mapping block, the situation of the subcarrier that is not taken by any signal launch point that promptly in said reference symbol put area, exists; Then said subcarrier is used to measure the interference that the signal launch point outside the CoMP collaboration region causes signal launch point in the CoMP collaboration region.In addition; Also possibly exist; In said reference symbol put area, have the situation that is used for the special-purpose subcarrier of certain allocated resource configuration mode, said subcarrier is used to measure the interference that the signal launch point outside the CoMP collaboration region causes signal launch point in the CoMP collaboration region.
Fig. 4 is the sketch map of reference symbol put area in two sub-frame among the present invention; As shown in Figure 4; In the process of using PDCCH to dispatch, possibly there is the Indication message of the position that comprises a plurality of basic mapping blocks, because the scheduling situation of each subframe at terminal is all inequality; Can reach the purpose of measuring whole frequency domain through the dynamic change of measured zone.As shown in Figure 4, in former and later two adjacent subframes, the frequency domain resource that the position of said basic mapping block occupies is different, when measuring the long characteristic of channel, can reach the purpose of measuring whole frequency domain.
The data that receive on the corresponding RE of terminal according to each resources pattern each corresponding PRB in each subframe; After adding up after a while; The data that can obtain sufficient density are calculated the long-time characteristic of channel of each resources pattern, choose the influential resources pattern in this terminal sign and feed back to the base station.
When in a sub-district, measuring, the situation that adjacent base station sends the PDSCH of same frequency may occur, then the base station is arranged in the reference symbol put area of dividing the common factor of the idle PDSCH of each base station, CoMP collaboration region; Perhaps, the transfer of data of mapping area is at first arranged in the base station, arranges the transfer of data of PDSCH again.
In addition; Owing to the signal launch point number among the CoMP is numerous; When the base station is added up through long term data; After long-time data statistics is carried out in the base station; If exist the channel quality of the pairing a plurality of signal launch points of different sub carrier to be lower than the threshold level at any terminal of said base station; And when the set of the Serving cell that the terminal of said a plurality of signal launch points is connected did not respectively overlap, when promptly said a plurality of signal launch points always can not also never be overlapped by the set that any terminal detected and can detect the Serving cell that the terminal of these two signal launch points connected respectively simultaneously, a plurality of signal launch points that then said channel quality is lower than the threshold level at any terminal used identical resources pattern.In the time of the sign of terminal to report resources pattern, distinguish the various signals launch point according to the pairing different service cells in each terminal.Promptly combine the corresponding Serving cell in this terminal to come unique sign of confirming this signal launch point.For preventing actual environment change, the signal launch point of reusing should regularly be tested again, and the signal launch point of reusing resources pattern with checking still can not received simultaneously and cause confusion.
In an embodiment of the present invention; The terminal is according to the data that on the corresponding RE of each resources pattern, receive; Calculate the signal to noise ratio on each signal launch point; Choose wherein signal to noise ratio will obtain signal to noise ratio and gives the base station greater than the resources pattern of designated value or the identification feedback of said resources pattern greater than the resources pattern of designated value after will measuring.Wherein, said designated value is set according to the actual disposition situation of base station, does not do qualification at this.In an embodiment of the present invention, said designated value can be that benchmark adds 3dB skew and sets with the maximum signal to noise ratio that receives.In another embodiment, said designated value is for being benchmark with the outer interference power of detected set, and search noise acoustic ratio is greater than the launch point of a certain fixed value, and wherein said fixed value is set according to the information actual conditions, like 3db.
In another embodiment of the invention, resources pattern and the positional information of said reference symbol put area in PDSCH with each signal launch point sends to the terminal through high-level signaling.Be specially: information and the positional information of reference symbol put area on PDSCH that marks off of the resources pattern of each signal launch point carried in the base station at high-level signaling.In order to reduce the transinformation of resources pattern in the high-level signaling; Resources pattern through each independent signal launch point in said reference symbol put area takies identical RE number of resources and well-regulated placement, and the terminal of said rule announcement is perhaps arranged in advance.
For example, in the said reference symbol put area, in said basic mapping block, occupy 1 number of sub-carrier on each signal launch point frequency domain, occupy 1 symbol on the time domain, and by distributing from small to large; Corresponding diagram 2 can be expressed as, the corresponding 0 work song carrier wave of the 1st signal launch point, the corresponding 1 work song carrier wave of the 2nd signal launch point.Parameter in the said rule (1,1) is sent to terminal or prior agreement.The terminal can be carried out between each signal launch point and the RE resource corresponding according to said rule, and the channel quality of the corresponding signal launch point of test on said RE resource obtains the long-term characteristics of signals of each signal launch point.
Use high-level signaling notice can not reach the effect that every subframe changes, but does the adjustment of reference symbol put area through the interval of long period, also can reach the similar effect of measuring whole frequency domain.
The terminal according to the base station announcement resources pattern, in the reference symbol put area of said PDSCH, each signal launch point carried out the measuring operation of channel.Through long data statistics, choose in all the signal launch points from said CoMP the influential signal launch point in this terminal, promptly this signal launch point corresponding signal to noise ratio of reference symbol of being launched is greater than designated value.The terminal feeds back to the base station with relevant parameters.
In sum; The present invention is through divide the reference symbol put area freely in the PDSCH zone; The RE that the reference symbol put area occupies can set according to actual conditions, in a sub-frame, holds the target that the signal launch point of more number is more measured thereby reach; When dividing this piece reference symbol put area, can consider the actual conditions of business datum flexibly in addition, reduce influence business.And through the correspondence one by one of launch point and resources pattern, count means such as configuration, reduced system's configuration information needed transmission capacity, also reduced the terminal information feedback quantity simultaneously through adopting same sub-carrier.
The above is merely preferred embodiment of the present invention, is not to be used to limit protection scope of the present invention.All any modifications of within spirit of the present invention and principle, being done, be equal to replacement, improvement etc., all be included in protection scope of the present invention.