Background technology
Insert evolution (High Speed Packet Access Plus in high-speed packet, HSPA+) system and Long Term Evolution (Long Term Evolution, LTE) in the future communications system such as system, in order further to improve message transmission rate and channel capacity, introduced the MIMO technology, that is, base station and terminal are launched a plurality of data flow simultaneously or are received a plurality of data flow.Adopted the communication system of MIMO technology to be called mimo system.
A lot of mimo systems also are time division duplex (TDD) systems simultaneously.The up-downgoing channel of TDD system can be used mutually, and promptly the up-downgoing channel has identical characteristic, can replace the characteristic of down channel with the characteristic of up channel.
Under many circumstances, Node B in the mimo system need operate accordingly according to the state of each down channel, for example, carry out based on singular value decomposition (Singular Value Decomposition, SVD) no codebook precoding, antenna mode switch, (Adaptive Modulationand Coding AMC) waits operation in the Adaptive Modulation decoding.If this mimo system also is the TDD system simultaneously, then can utilize the characteristic that the up-downgoing channel can be used mutually in the TDD system, carry out corresponding uplink channel estimation by Node B according to the signal of each root antenna transmission of UE, to carry out channel vector that uplink channel estimation obtains channel vector at every antenna as corresponding down channel, form complete channel matrix H by the channel vector of each down channel, and then operate accordingly according to complete channel matrix H.Wherein, each element that carries out the channel vector that uplink channel estimation obtains at every antenna is the channel fading coefficient between all antennas of this every antenna and Node B.
For example, the number of antennas of supposing Node B is N nb, the number of antennas of UE is 2, in no codebook precoding based on SVD, Node B end carries out uplink channel estimation, obtain the channel matrix H of complete N nb * 2, Node B carries out SVD to complete channel matrix H and decomposes and to obtain the certain characteristics vector then, and the characteristic vector number is the order of complete channel matrix H.When Node B need walk abreast m downstream data flow of transmission (m is not more than the order of complete channel matrix H), Node B selects the characteristic vector of a corresponding m eigenvalue of maximum from the characteristic vector that SVD decomposites, each characteristic vector of selecting is used for armed data flow of weighting.In like manner, technology such as antenna mode switching and AMC also often need to utilize complete channel matrix H in conjunction with factors such as detection algorithms, obtain the signal to noise ratio of each data flow under each antenna mode, and then carry out antenna mode switching and/or AMC operation.
As seen, obtain complete channel matrix H great important is arranged.
At present, the hardware of considering UE is realized and problem such as cost loss, in the TDD system, usually the many antennas that limited UE can only be used for the while downlink data receiving to obtain receive diversity, but can not send upstream data simultaneously, each antenna of UE only when being assigned with uplink physical channel, could send upstream data.This is for the TDD system that has adopted the MIMO technology, and Node B can only obtain the channel vector of the every antenna of UE by uplink channel estimation in each TTI, and can't obtain complete channel matrix H.
At obtaining this technical problem of complete channel matrix H at synchronization at present, prior art has proposed two kinds of solutions, the first utilizes the occasion of complete channel matrix H to use the technology that other do not need complete channel matrix H instead at needs, it two is, each antenna by UE sends uplink detection (sounding) signal to Node B respectively, Node B estimates the channel vector of each antenna respective channels respectively according to the up sounding signal of each antenna transmission, forms complete channel matrix H by each channel vector.
For preceding a kind of method, utilize the occasion of complete channel matrix H to adopt the technology that only depends on the local channel matrix at needs, can make communication performance that certain loss is arranged, for example, when Node B employing is launched a plurality of data flow based on the no codebook precoding of SVD, can obtain near optimum in theory performance, if but the technology such as beam shaping (Beam forming) and/or antenna grouping of using instead realize multithread MIMO emission, owing to do not make full use of the full detail of space channel, can't use optimum equivalent wave beam (beam) territory that whole aerial array provided of Node B to launch data, therefore can cause performances such as array gain and power gain to reduce.Wherein, the Beam forming technology channel matrix that only need obtain UE single antenna correspondence can be realized multithread MIMO emission.
For a kind of method in back, also do not propose to send the concrete scheme of up sounding signal at present in the prior art, therefore, in fact prior art also can't provide its needed up sounding signal for estimating complete channel matrix H.
Embodiment
For making purpose of the present invention, technical scheme and advantage clearer, below with reference to the accompanying drawing embodiment that develops simultaneously, the present invention is described in more detail.
Fig. 1 is the method flow diagram that sends up sounding signal in mimo system provided by the invention, and as shown in Figure 1, this method comprises:
Step 101, UE receives the scheduling message of Node B, if receive described scheduling message, execution in step 102, otherwise, continue execution in step 101.
Step 102 estimates that according to the pre-configured needs of network side the conditional parameter of complete channel matrix H judges whether needs estimation complete channel matrix H, if, execution in step 103, otherwise, step 101 returned.
In this step, can judge whether needs estimation complete channel matrix H according to described conditional parameter, also can judge whether to need to estimate described complete channel matrix H by Node B by UE.
Step 103, each antenna of UE sends up sounding signal to NodeB respectively according to the pre-configured signal transmission parameter of network side.
In this step, in Node B side, Node B receives sounding signal from each antenna of UE according to described configuration, estimates the channel vector of each antenna correspondence according to the sounding signal of each antenna, forms complete channel matrix H by the channel vector of each antenna.
The present invention proposes, need to estimate that the conditional parameter of complete channel matrix H can be parameters such as channel quality thresholds or downlink data traffic volume, after then UE receives the scheduling message of Node B, can trigger this UE according to the channel quality between Node B and the UE by UE and send up sounding signal to Node B, also can be when needs to be estimated complete channel matrix H by Node B, the mode of employing signaling triggers UE and sends up sounding signal to Node B.Wherein, Node B can judge whether needs estimation complete channel matrix H according to the size of channel quality between Node B and the UE or downlink data amount.Node B can define new signaling, sends up sounding signal by this new signaling UE to Node B, also can adopt the state notifying UE that is not used in the existing signaling message to send up sounding signal to Node B.
If UE is after receiving scheduling message, trigger UE by UE or Node B according to current channel quality and send up sounding signal to Node B, the pre-configured channel quality thresholds of network side then, at current channel quality during greater than described channel quality thresholds, trigger UE and send up sounding signal to Node B, otherwise, do not trigger UE and send up sounding signal to Node B.
Described network side be generally radio network controller (Radio Network Controller, RNC).Described channel quality thresholds can be a signal to noise ratio SINR threshold value, perhaps with SINR threshold value corresponding channel quality indication information (Channel Quality Indication, CQI) threshold value.
Particularly, the pre-configured channel quality thresholds of network side, UE receives the schedule information that Node B sends on down control channel HS-SCCH, receive downlink traffic channel HS-PDSCH message according to this schedule information, HS-PDSCH message is measured current channel quality, and whether UE judges current channel quality greater than described channel quality thresholds, if, then explanation needs to estimate complete channel matrix H, and each antenna of UE sends up sounding signal to Node B respectively.Perhaps, Node B receives the HS-SICH message of UE feedback, whether judges the CQI information of carrying in this HS-SICH message greater than CQI information threshold value, if, then explanation needs to estimate complete channel matrix H, and Node B notice UE sends up sounding signal to Node B.
Particularly, the problem that relates to of the method for the up sounding signal of transmission provided by the invention comprises: UE sends the concrete form of the concrete opportunity of up sounding signal, up sounding signal, the condition that stops to send up sounding signal, Node B side and how to determine when to receive the sounding signal of sounding signal and reception specifically by which antenna transmission in the process that is scheduled.Below, in conjunction with the detailed process of the method that sends up sounding signal in the mimo system, to send up sounding signal to Node B be example to trigger this UE by UE according to the channel quality between Node B and the UE, and the problems referred to above are set forth.
Fig. 2 is the detail flowchart that sends the method for up sounding signal in the mimo system provided by the invention.Wherein, the network side configuration needs to estimate the conditional parameter of complete channel matrix H and sends the required various signal transmission parameters of up sounding signal, in Fig. 2, with described conditional parameter is that channel quality thresholds is that example describes, in the practical application, described conditional parameter is not limited to channel quality thresholds, and described signal transmission parameter includes but not limited to timer dispatching cycle (Timer) timing length and is used for determining the up sounding signal of the transmission time parameter on opportunity.As shown in Figure 2, this method comprises:
Step 201, Node B dispatches the UE that possesses the MIMO ability.
In this step, among Node B each UE to the communication network that enters this Node B and covered, the UE that possesses the MIMO ability dispatches, and sends scheduling message by the HS-SCCH channel to the UE that is scheduled.
Carry transport format information, resource allocation information and HARQ information etc. in the described scheduling message.
In this step, Node B is when initial transmission, adopt the single-stream transmission pattern to send downstream data flow to UE, after waiting to estimate complete channel matrix H, the self adaptation of carrying out single current and multi-streaming transmission mode is again switched, better can adopt multi-streaming transmission mode to send downstream data flow to UE under the channel condition, described channel condition obtains by complete channel matrix H is assessed.
Step 202, UE receives the scheduling message of Node B, and estimates current channel quality according to scheduling message.
In this step, UE according to the sequential relationship of the middle regulation of stipulating among the 3GPP standard TS25.221, receives downlink traffic channel HS-PDSCH message according to the physical resource of indicating in the scheduling message in corresponding TTI.
UE measures HS-PDSCH message, obtains current channel quality.Wherein, this current channel quality can be SINR, also can be the CQI information corresponding with SINR.This current channel quality can be SINR value or the CQI value that single records, and also can be the mean value of each SINR that arrives that repeatedly measures or the mean value of CQI.
In step 201~202, if Node B continuous dispatching UE, then Node B is passing through the HS-SCCH channel after UE sends scheduling message, send a HS-PDSCH message to UE, if Node B semi-continuous scheduling UE, then Node B sends a plurality of HS-PDSCH message passing through the HS-SCCH channel after UE sends scheduling message to UE.
Step 203, whether UE judges current channel quality greater than channel quality thresholds, if, execution in step 204, otherwise, step 202 returned.
Step 204, each antenna of UE sends parameter according to the coherent signal of network side configuration, sends up sounding signal to NodeB.
In this step, the signal of network side configuration sends relevant parameter and comprises: the condition that is used for determining the form of the up sounding signal of the transmission time parameter on opportunity, up sounding signal and stops to send up sounding signal.
In this step, each antenna of UE sends up sounding signal to Node B according to described time parameter respectively in the corresponding moment.
Particularly, described time parameter comprises: periodically send the time parameter of up sounding signal, then UE sends the time parameter of up sounding signal according to described periodicity, periodically sends up sounding signal.That is to say that be the opportunity that sends up sounding signal: UE periodically sends up sounding signal according to the time parameter of network side configuration.
Wherein, the described periodicity time parameter that sends up sounding signal comprises: subframe time migration T
Offset, period T s and in TTI, send the ascending time slot position of up sounding signal.UE is according to T
OffsetJudge whether to send up sounding signal to Node B in current TTI with Ts, that is, UE is according to (2 * SFN+S-T
Offset) mod Ts=0 judges whether to send up sounding signal to NodeB in current TTI, if above-mentioned equation is set up, then the ascending time slot position of the up sounding signal of described transmission sends up sounding signal to Node B in current TTI.Wherein, mod represents modulo operation, T
OffsetWith the value of Ts all are numbers of TTI, SFN is the System Frame Number at current TTI place, S is the subframe numbers at current TTI place, the S value is 0 or 1.
Send up sounding signal opportunity can also for: UE when the Node B feedback HS-SICH message, if there is other ascending time slot except the ascending time slot at HS-SICH place in the TTI at feedback HS-SICH message place, then send up sounding signal to Node B, and adopt different UE antenna transmission HS-SICH message and send up sounding signal at described ascending time slot.Wherein, UE sends moment of up sounding signal to Node B first after receiving scheduling message should be after UE feeds back HS-SICH message, so that Node B determines whether to receive up sounding signal in the corresponding moment according to the HS-SICH message of UE feedback.NodeB and UE can make an appointment and send the antenna that HS-SICH message adopts.
In addition, if when in TTI, having a plurality of ascending time slot that can send up sounding signal, the different up sounding signal of antenna transmission of employing on each ascending time slot of up sounding signal can sent.
The form of described sounding signal can be the training sequence code displacement Midamble shift of the free time of distributing for UE.Wherein, can be that UE distributes idle Midamble shift by the spreading factor that UE is set.Wherein, UE can be according to the configuration of the high-level signaling of network side, by each idle Midamble shift of the UE time division multiplexing in the same sub-district.
If in the time slot that sends up sounding signal place, there is HS-SICH message to need feedback, then described sounding signal can also be described HS-SICH message.
The condition that stops to send up sounding signal can be: dispatching cycle, Timer was overtime, and perhaps, the continuous predetermined number contents of UE is judged current channel quality and is not more than described channel quality thresholds.Satisfy stop to send the condition of up sounding signal after, UE does not send up sounding signal to Node B in the current scheduling process.
If dispatching cycle, Timer was overtime, illustrate that then current dispatching cycle is long, UE can stop to send up sounding signal, this be because, generally, the initial data-transmission mode that adopts was single-stream mode or multithread pattern when the complete channel matrix H that upgrades in current dispatching cycle was generally used for assessing Node B and dispatches UE next time, if current dispatching cycle is long, then the complete channel matrix H of Geng Xining can't reflect the channel condition when Node B dispatches UE next time, therefore, in current dispatching cycle, needn't estimate complete channel matrix H, and when dispatching UE next time, directly adopt single-stream mode to send downlink data to UE.Wherein, UE receives HS-SCCH message in the continuous dispatching process, perhaps receives HS-PDSCH message in the semi-continuous scheduling process, and then UE starts or restarts Timer dispatching cycle.
Judge current channel quality k time and be not more than described channel quality thresholds (k is a predetermined value) if UE is continuous, illustrate that then the channel quality between UE and the Node B is very poor, be unsuitable for adopting multi-streaming transmission mode, therefore, needn't estimate complete channel matrix H, therefore, can stop to send up sounding signal.
The concrete value of k and dispatching cycle Timer timing length can obtain by l-G simulation test or field testing.
Step 205, the up sounding signal that each antenna of Node B reception UE is sent.
In this step, Node B is according to the relevant parameter of network side configuration, determines the up sounding signal that receives is by which antenna transmission of UE.
Particularly, UE carries current channel quality in the scheduling according to Node B in the HS-SICH message of described Node B feedback, Node B judges that whether the current channel quality that carries in the HS-SICH message of UE feedback is greater than the default channel quality thresholds value of network side, if then Node B begins to receive the sounding signal from each antenna of UE.
Node B begins to receive after the sounding signal from each antenna of UE, and according to the time parameter of network side configuration, the moment that sends up sounding signal at UE receives the sounding signal that respective antenna sends.
Wherein, can make an appointment moment of the up sounding signal of each antenna transmission of UE by Node B and UE, perhaps, agreement UE sends the antenna of up sounding signal employing and the order of the up sounding signal of each antenna transmission first in each dispatching cycle.
For example, UE only adopts 2 antennas usually at present, adopt at UE under the situation of 2 antennas, UE and Node B can fix on the antenna that sends up sounding signal in each dispatching cycle first approximately, after sending up sounding signal first, 2 antennas of UE alternately send up sounding signal.
In fact, step 204 among Fig. 2 and step 205 are carried out synchronously, that is to say, UE is in the process that sends up sounding signal, and Node B receives the sounding signal in real time.
Step 206, the up sounding signal that Node B sends according to each antenna of UE estimates complete channel matrix H.Process ends.
In this step, the up sounding signal that Node B sends according to the every antenna of UE estimates the channel vector of this root antenna correspondence of UE, forms complete channel quality matrix H by the channel vector of each antenna correspondence of UE.Each element of described channel vector is respectively that this root antenna of UE is to the channel fading coefficient between each antenna of Node B.
Node B is in the process of scheduling UE, before estimating complete channel matrix H, adopt the single-stream transmission pattern to send data to UE, after estimating complete channel matrix H, assess current channel condition according to complete channel matrix H, switch between single-stream transmission pattern and multi-streaming transmission mode according to the current channel condition of assessing out, adopt the transmission mode after switching to send data to UE.Can adopt existing techniques in realizing to assess current channel condition according to complete channel matrix H.
The invention provides UE and send the complete scheme of up sounding signal to Node B, thereby for estimating that complete channel matrix H provides its needed up sounding signal.
And, because the present invention has disposed the conditional parameter that needs to estimate complete channel matrix H by network side in advance, only when judging needs according to described conditional parameter and estimate that complete channel matrix H and UE are scheduled, just send up sounding signal to Node B, therefore, needn't be when not needing to estimate complete channel matrix H and UE also send up sounding signal when not being scheduled, can save the communication resource on the one hand, on the other hand, can be the UE power saving.
Again further, when the up sounding signal of UE transmission is Midamble shift, owing to do not need uplink physical channel can send Midamble shift, therefore, when UE is up sounding signal with Midamble shift, as long as there is ascending time slot, then UE can send up sounding signal, and just send up sounding signal needn't be assigned with uplink physical channel by the time the time, it is shorter that each antenna of UE all sends the cycle of once up sounding signal, correspondingly, Node B is also shorter according to the cycle that up sounding signal estimates complete channel matrix H, thereby makes the complete channel matrix H estimate real-time tracking channel space condition well.
The above is preferred embodiment of the present invention only, is not to be used to limit protection scope of the present invention, all any modifications of being made within the spirit and principles in the present invention, is equal to replacement, improvement etc., all should be included within protection scope of the present invention.