CN102970067B - A kind of method for realizing continuous print broadband connections - Google Patents

Abstract

The present invention proposes a kind of method for realizing continuous print broadband connections.In the high-speed railway communication plan that the present invention proposes a kind of improvement, first, the network architecture is improved, virtual single cell topology is provided.Further, base station is by the positional information of Remote Radio Unit, and choosing suitable Remote Radio Unit is that user terminal is served.When base station selection, multiple Remote Radio Unit is user terminal when serving, and according to the channel condition information of the plurality of Remote Radio Unit respectively and between user terminal, carries out united beam shaping preliminary treatment to sent signal.

Description

A kind of method for realizing continuous print broadband connections

Technical field

The present invention relates to wireless broadband communication, particularly relate to the network topology structure in wireless broadband communication and beamforming patterns.

Background technology

WiMAX is becoming possibility in recent years.Online multimedia, game, application download etc., become the main business in mobile network.In order to train such as, between Beijing and Shanghai with 350km/h speed run China Railway High-speed (CRH) on passenger data-intensive application is provided, wish to develop a kind of access network, be characterized in there is high bandwidth and high rate travel can be resisted.In recent years, in order to make traditional GSM framework adapt to high-speed railway communication (High-SpeedTrainCommunication, HSTC), carried out multiple effort, thus created GSM-R, GSM-R is the GSM standard being exclusively used in railway.GSM-R ensure that with the speech business of the passenger on the train that 500km/h runs, and disposes along most high-speed railway rail.But the challenge that GSM-R faces is that GSM-R lacks broadband data service support, this means that passenger cannot obtain Online Video or game in train journey process.

Traditional framework of HSTC system is similar to conventional GSM cellular system, as shown in Figure 1.In FIG, the base station of GSM-R, such as eNB1 and eNBk, dispose along rail.Therefore, require that adjacent base station has overlapping overlay area, to ensure sufficient switching time.Such as, overlapping overlay area is there is between the community that the administrative community of base station eNB 1 is administrative with base station eNB k, in addition, by between the administrative different Remote Radio Unit (RemoteRadioHead, RRH) of same eNB, also overlapping overlay area must be had, such as, between RRH1 and RRH2 ..., between RRHk and RRHk+1, there is overlapping overlay area respectively.

The problem of traditional HSTC system based on RRH is, along with the raising of train translational speed, system suffers the serious Special Handle of Drop Question caused by handoff failure.Avoid the large alternate covering region that handoff failure needs between adjacent community, this also just means the significant reduction covering efficiency.By Guo, Hui; Wu, Hao; Zhang, " GSM-RNetworkPlanningforHighSpeedRailway " that Yushu delivers, Wireless, MobileandMultimediaNetworks (ICWMNN2010), IET3rdInternationalConferenceon, 26-29Sep.2010, p10-13, in Beijing, China (" the GSM-R network planning of high-speed railway "), give some for studying the analysis of the radius of society restriction for meeting overlapping requirement.Research finds, the requirement of overlapping region can cause covering efficiency to reduce by 30%.

Another challenge that HSTC system faces is, because high-speed mobile, creates Doppler frequency shift.Doppler frequency shift causes interchannel interference (Inter-channel-interference, ICI), thus limits link data rates.Most traditional HSTC scheme only considers that the interchannel interference of receiver side is eliminated.Because usually poor than the disposal ability of the base station of rail side in the disposal ability of vehicle-mounted mobile unit, also namely computing capability is poor, and number of antennas is less, and surrounding environment is poor, etc., therefore, the enhancing in receiver on-board side possibly cannot provide gratifying performance.In addition, consistent Consumer's Experience can not be provided for all users belonging to a specific operator in the enhancing of receiver side.

According to the analysis in " GSM-RNetworkPlanningforHighSpeedRailway " literary composition, for GSM-R system, traditional handoff procedure needs 8 second time to complete.And the switching do not completed can cause call drop.For the train run with 450 kilometers of speed per hour, what this means that adjacent community needs 1.1 kilometers does not overlapping coveredly cause call drop to ensure sufficient switching time.Considering that typical radius of society is 3 kilometers, this means the great reduction to covering efficiency.

Switching delay causes primarily of following 2 factors:

1. adjacent base station uses different wireless channels.Therefore, when train moves to another community from a community, need to distribute new channel, and discharge old channel.Need to coordinate between the base station distributing this new channel and the base station distributing this old channel.

2. base station is distributed usually on geographical position.Therefore, depend on the link with larger delay alternately between these base stations, such as, there is the X.2 link of the delay of level second.

3. the decision-making switched, to perform and complete the cross-layer protocol be included between different network entities mutual, such as, mutual between physical layer (PHYlayer), media access control layer (MAClayer), network layer (Netlayer), wireless chain control layer (RadioLinkControl, RLC).And high-level signaling can bring more obvious delay usually.

Summary of the invention

Based in the HSTC framework of conventional cell, be difficult to overcome the problems referred to above.Therefore, the present invention proposes a kind of HSTC scheme of improvement, first, the network architecture is improved, virtual single cell topology is provided.Further, base station is by the positional information of RRH, and choosing suitable RRH is that user terminal is served.When base station selection, multiple RRH is user terminal when serving, and according to the channel condition information of the plurality of RRH respectively and between user terminal, carries out united beam shaping preliminary treatment to sent signal.

According to a first aspect of the invention, provide a kind of in a base station for providing the method for continuous print broadband connections for the user terminal of high-speed mobile, wherein, multiple Remote Radio Unit is administrative by described base station, the plurality of Remote Radio Unit shares identical running time-frequency resource, and the method comprises the following steps: A. obtains current location and the translational speed of described user terminal; B. according to described current location and the described translational speed of described user terminal, select at least one Remote Radio Unit for the transfer of data of described user terminal.

According to a second aspect of the invention, provide a kind of method of carrying out united beam shaping in Remote Radio Unit according to the instruction of base station, comprise the following steps :-receive the indication information carrying out united beam shaping from this Remote Radio Unit indicated by described base station, wherein, this indication information comprises and makes the maximized weight of the Signal to Interference plus Noise Ratio of Received signal strength;-utilize channel matrix between this Weight user terminal and this Remote Radio Unit, with compensating for doppler frequency deviation.

Adopt the solution of the present invention, preferably, the RRH Choice adopting the network topology structure of virtual single community and assist with positional information, within the specific limits, no longer need cell merge process, therefore, the cutting off rate caused by handoff failure can be greatly diminished.

Preferably, when choosing multiple RRH and carrying out business transmission, the beam forming based on ICI of the present invention, compared with traditional high specific transmit beamforming scheme, even if under the speed per hour of 450kmph, still brings the link performance gain of at least 1.5dB.This gain can guarantee more reliable transfer of data.

Accompanying drawing explanation

Read the following detailed description to non-limiting example by referring to accompanying drawing, further feature of the present invention, object and advantage will be more obvious.

Fig. 1 shows network topology structure schematic diagram of the prior art;

Fig. 2 shows the network topology structure schematic diagram according to a specific embodiment of the present invention;

Fig. 3 shows the systems approach flow chart according to a specific embodiment of the present invention;

Fig. 4 shows the network topology structure schematic diagram when selecting multiple RRH;

Fig. 5 shows for three kinds of different transmission preprocess methods, the impact when RRH covering radius changes on systematic function.

Wherein, same or analogous Reference numeral represents same or analogous steps characteristic or device/module.

Embodiment

Although be described for bullet train herein, but, those skilled in the art will be understood that the present invention is not limited only to bullet train, and the present invention is equally applicable to the vehicles that ground traffic tools, aircraft etc. on highway travel along set route or course line.

Fig. 2 shows system topology schematic diagram according to a particular embodiment of the invention.This system is made up of 3 assemblies, is respectively row in-vehicle network (In-TrainNetwork, ITN), and train is to ground network (Train-to-GroundNetwork, TGN) and ground network (GroundNetwork, GN).In the present invention, TGN comprises vehicle-mounted train access unit (TrainAccessUnit, TAU), rail side Remote Radio Unit (RemoteRadioHeader, RRH), and baseband processing unit (BaseBandUnit).TAU is used for being responsible for communicating with rail side RRH via air interlace channel.The number of the TAU disposed ON TRAINS depends on the transmission bandwidth between customer service capacity and train to ground.Below, for train deploy, TAU unit is described for we, it will be understood by those skilled in the art that TAU is access device, and it has the function convergence of the multiple user terminals on train accessed.Certainly, train also can not comprise TAU access device, but directly be communicated with RRH by user terminal.Therefore, the information between user terminal and RRH mutual, had both comprised the information interaction of RRH directly and between user terminal, and had also comprised user terminal via TAU, carry out information interaction with RRH.

In fig. 2, such as, optical cable at a high speed can be adopted between RRH and BBU to connect.In addition, although adopt the mode of chain to connect between the multiple RRH shown in Fig. 2, it will be understood by those skilled in the art that and also can adopt other topological structures such as Y-connection or annular connection between RRH, these distortion still belong within protection scope of the present invention.

Be different from the network topology structure schematic diagram shown in Fig. 1, in the network topology structure schematic diagram of Fig. 2, RRH1, RRH2, RRH3......RRHk are managed by same group of BBU, also be, these RRH belong to same virtual single community, also namely, according to the maximum length of the link from BBU to RRH, be multiple part along rail by interval division.Wherein, each part comprises multiple RRH, these RRH covered by a base station, and, share any one in same cell ID, cell special reference, scrambler and cell-specific broadcast channel and cell-specific control channel between these RRH or appoint multinomial.

It will be understood by those skilled in the art that BBU is arranged in base station, BBU has the processing capacity of base band, and in this manual, we represent base station with BBU.And RRH is radio frequency transmission unit, not there is the function of Base-Band Processing.

When train moves to adjacent RRH from service RRH, because this service RRH and adjacent RRH is administrative by same group of BBU, these RRH share community ID, cell special reference etc., therefore, do not need, for the user terminal on train carries out cell merge, not need the resource switching to transfer of data to distribute yet, namely, do not need to carry out traditional switching yet.

Fig. 3 shows the systems approach flow chart according to a specific embodiment of the present invention.First, in step s 30, BBU obtains current location and the translational speed of user terminal.Be all different arbitrarily from customer location and user moving speed in common cell mobile communication systems, HSTC system is used for railway, and wherein, rail is all fixing, and the speed of service of train also can obtain easily.

Certainly, the translational speed of this user terminal had both comprised the rate travel of this user terminal, comprised again the direction of the movement of this user terminal.

Then, in step S31, BBU, according to the current location of user terminal and translational speed, selects at least one RRH for the transfer of data of this user terminal.

Any one in following two kinds of modes can be adopted for obtaining the current location information of train.Mode one is that this dedicated channel can utilize more effective error control mechanism based on the special control channel between user terminal and TGN, such as, and the Turbo code of 1/3 code check, and low-order-modulated mode, such as QPSK modulation.This scheme, to sacrifice data rate for cost, has exchanged a more reliable data channel for, transmits to the geography information of BBU for by TGN.The positional information of user terminal is obtained by the GPS transceiver installed ON TRAINS, and is reported to BBU by special control channel.

In a further mode of operation, transducer can be disposed along rail, for detecting and reporting the positional information of train.When train is through transducer, transducer is triggered and measures the speed of service of train and position, and by these information reportings measured to the controller in BBU.BBU, based on this report, selects and switches the RRH for transmitting.This mode requires extra sensor network, but which does not need special control channel, and it is higher that the business for user terminal transmits the resource utilization of distributing.Which to be applicable in high-speed railways, in order to railway maintenance and driverless train control (automatictraincontrol) object, install the scene of sensor network.The example of this scene comprises and is integrated with communication-based train control (Communication-BasedTrainControl, CBTC) high speed rail system, see R.D.Pascoe, and T.N.Eichorn, " Whatiscommunication-basedtraincontrol? " (what is communication-based train control), IEEEVehicularTechnologyMagazine, vol.4, no.4, pp.16-21, Dec.2009, it discloses the method obtaining accurate speed and positional information.

BBU, according to certain strategy, selects RRH.BBU can select 1 RRH, also can select multiple RRH.When the selected data for being train simultaneously of multiple RRH are transmitted, link data rates can be improved.But, when multiple RRH transmits simultaneously in elected, because the plurality of RRH shares identical channel and cell parameter, may common-channel interference be produced between these RRH, and the expected gain of multicast communication is difficult to obtain.

BBU selects the strategy of RRH can comprise distance at least one RRH immediate selected with user terminal.Such as, this strategy can comprise only selects a RRH to be subscriber terminal service as the RRH selected, and this strategy also can comprise selects multiple RRH to be subscriber terminal service as the RRH selected.

Indicate not selected RRH to reduce transmitting power for not selected RRH, BBU, or close transmitting power.

Therefore, when in elected, multiple RRH is subscriber terminal service, in step s 32, BBU obtains the channel condition information between user terminal and each selected RRH.

Then, in step S33, BBU, according to channel condition information, carries out united beam shaping to sent signal, with compensating for doppler frequency deviation.

Particularly, first set up the channel model of the ofdm system under high-speed mobile, then according to this signal model, describe the sufficient channeling in order to obtain between selected multiple RRH in detail, and reduce impact at a high speed, and the united beam forming arrangements carried out.

We consider the joint transmission of the selectable ofdm signal of RRH, the RRH of all selections has K root antenna.From different transmit antennas signal from experienced by different time varying channels between reception antenna.But according to the distribution leaving angle (AngleofDeparture, AoD) of the signal of dispersion, there are some correlations in the interval between antenna element and the electromagnetic coupling effect between these antenna unit between these channels.

Only consider the link between ground to train because this link more easily becomes the data-intensive broadband services in high ferro, such as, Online Video, game, download etc., bottleneck.In addition, suppose that the BBU of rail side has the correlation information of the non-time-varying part of channel channel time become part and the cross-correlation between these channels wherein, get desired value in time domain and subcarrier, to form K × K matrix R respectively _hH, R _{h ' H '}, and R _{h ' H}.Also namely, matrix notation be R _hH, matrix notation be R _{h ' H '}, matrix notation be R _{h ' H}.

For TTD system, because up link and down link share identical frequency band, therefore, BBU side, by utilizing the up-downgoing reciprocity in TDD system, obtains above-mentioned channel information.And for FDD system, can be estimated by down channel and feed back to obtain above-mentioned information.

Under this scene, be different from traditional beam forming solutions, in the present invention, the beam forming carried out for each OFDM symbol launched in time domain, this beam forming for K root antenna time become beam-forming weights w (t)=[w ₁(t), w ₂(t) ... w _k(t)] ^t.Therefore, the signal through beam forming conversion can be represented as:

s(t)＝w(t)u(t)(1)

Wherein, u (t) represents subscriber signal.The choosing of w (t) depends on the requirement of correlation between channel and computation complexity.Notice that the weight w (t) of beam forming can be expanded into following Taylor expansion approx:

w _i(t)＝w _i(t ₀)+w′ _i(t ₀)(t-t ₀)+O((t-t ₀) ²)(2)

Which form common beam-forming weights vector

w(t)≈w ₀+(t-t ₀)w ₁(3)

Utilize formula (3), approximate beam-forming weights can be constructed to precision and the complexity of hope.In the present invention, single order can be restricted to by approximate.Therefore, the signal received by RRH can be approximately:

r _p(t)≈D _p(t)+I _p(t)+n(t)(4)

Wherein, $D_p\left(t\right)={\mathrm{\Σ}}_{n=0}^{N-1}{H}_n\left(t_0\right)w_0{e}^{j2\mathrm{\πn}{f}_{s}t}{u}_n---\left(5\right)$

$I_p\left(t\right)={\mathrm{\Σ}}_{n=0}^{N-1}(t-t_0)[H_n^{\′}\left(t_0\right)w_0+H_n\left(t_0\right)w_1]e^{j2\mathrm{\π}{\mathrm{nf}}_{s}t}{u}_n---\left(6\right)$

Formula (5) represents the signal section of wishing, formula (6) represents interference sections.

For a given w ₀and w ₁, the power section that the power of the ICI generation of the signal section of wishing, signal and noise produce can be represented as respectively:

$P_D=E\left\{\mathrm{tr}\left(D_p\left(t\right)\right)\right\}$ (7)

$=E\left\{\mathrm{tr}\left(H_n\left(t_0\right)w_0{w}_0^H{H}_n^H\left(t_0\right)\right)\right\}$

P _I＝E{tr(I _p(t))}(8)

$P_N={\mathrm{\σ}}_n^2---\left(9\right)$

Therefore, the ratio (Signal-to-InterferenceplusNoiseRatio, SINR) of the signal of wishing and ICI and noise can be represented as:

$\mathrm{SINR}=\frac{P_D}{P_I+P_N}---\left(10\right)$

SINR is received, by the optimization problem of SINR definition vector parameter in order to maximize:

$\mathrm{\ω}=\left[\begin{array}{c}{w}_1\\ w_0\end{array}\right]---\left(11\right)$

Make Θ _n=[0 _{1 × K}h _n], ∏ _n=[H _nh ' _n], and select t ₀=1, therefore, SINR can be rewritten as:

$\mathrm{SINR}=\frac{P_D}{P_I+P_N}$

$=\frac{E\left\{\mathrm{tr}\left({\mathrm{\Θ}}_n\mathrm{\ω}{\mathrm{\ω}}^H{\mathrm{\Θ}}_n^H\right)\right\}}{E\left\{\mathrm{tr}\left({\mathrm{\Π}}_n\mathrm{\ω}{\mathrm{\ω}}^H{\mathrm{\Π}}_n^H\right)\right\}+{\mathrm{\σ}}_n^2}---\left(12\right)$

$=\frac{E\left\{\mathrm{tr}\left({\mathrm{\ω}}^H{R}_{\mathrm{\Θ}}\mathrm{\ω}\right)\right\}}{E\left\{\mathrm{tr}\left({\mathrm{\ω}}^H{R}_{\mathrm{\Π}}\mathrm{\ω}\right)\right\}}$

Wherein, and because R _Θand R _∏be covariance matrix, they are the close conjugation of positive definite strategic point.Therefore, optimization SINR problem is vague generalization Rayleigh entropy problem, and the solution of this problem is and maximization matrix bunch (R _Θ, R _∏) the corresponding characteristic vector of general characteristic value, such as, $\mathrm{\ω}=\underset{\mathrm{\ω}}{\arg \max }\left(\frac{E\left\{\mathrm{tr}\left({\mathrm{\ω}}^H{R}_{\mathrm{\Θ}}\mathrm{\ω}\right)\right\}}{E\left\{\mathrm{tr}\left({\mathrm{\ω}}^H{R}_{\mathrm{\Π}}\mathrm{\ω}\right)\right\}}\right)---\left(13\right)$

$=g\_\mathrm{eig}\_{\mathrm{vec}}_{\max }(R_{\mathrm{\Θ}},R_{\mathrm{\Π}}).$

Wherein, R _Θand R _∏can obtain from known channel related information.

Therefore, the object that this united beam is shaped is, calculate the maximized weight of Signal to Interference plus Noise Ratio of the Received signal strength from BBU that TAU is received, with the signal that this Weight is to be sent, with compensating for doppler frequency deviation, the Signal to Interference plus Noise Ratio of this Received signal strength represent Received signal strength time constant part power relative to the ratio of the interference power caused because of time varying signal and channel noise power sum.

Then, BBU utilizes channel estimating and formula (1) to formula (13), carry out precoding to sent signal u (t), and send this signal through precoding by the RRH that chooses to TAU, the signal also namely received by TAU is Received signal strength r _p(t), wherein, r _p(t) ≈ D _p(t)+I _p(t)+n (t).

Then, the TAU unit on train receives the signal from RRH, decoded data, and these data are routed to object Service Access Point (Multi-standardAccessPoint, MAP), and is finally transferred to user terminal.

Numerical Validation

We provide numerical result, can provide higher data transfer rate to show HSTC scheme of the present invention for the railway passenger of high-speed cruising.Suppose that each RRH in this HSTC system all has multiple directions antenna.By suitably placing antenna, RRH can cover the both sides that its radius is R.Select 3 adjacent RRH for serving 2 TAU of front portion and the afterbody laying respectively at train at every turn.These two TAU are configured to be positioned at different frequency bands, and each TAU takies 20MHz bandwidth.

Adopt the relevant Rayleigh channel modeling mobility based on inverse discrete Fourier transform method.Interval between the antenna of RRH and TAU is enough large, therefore, is independently between the element of channel matrix H.Channel condition information (CSI) obtains by estimating reference signal at receiver side, and obtains by the up-downgoing reciprocity in TDD system or by the feedback in FDD system at transmitting pusher side.For the OFDM channel between RRH and TAU, suppose N=2048 subcarrier.Further hypothesis Transmission Time Interval (TransmissionTimeInterval, TTI) T _tTI=1ms, and each TTI comprises M=14OFDM symbol.Therefore, the duration of OFDM symbol is 71.4 microseconds, consistent with the design of 3GPPLTE.The symbol rate of this system is provided by following formula:

R _s＝(1-γ)NM/T _TTI

Wherein, γ is signaling consumption, is up to 35% for LTE system.Then, compute sign rate is R _s=18.637 × 10 ⁶symbol/second.

The Turbo code of code-rate-compatible is adopted to be used for error control.The bit rate of system is determined by modulation coding mode (ModulationandcodingScheme, MCS), can provide gratifying error control performance for given input SINR, this MCS.

Table one shows the effective data transfer rate required for different MCS and SINR, and the SINR to demodulator input needed, with reach 10 ^-5bit error rate, for different MCS, it is considered to the scene of zero defect usually.

Table one

From table one, can find out, in order to ensure the peak-data rates of 100Mbps to the user terminal be loaded with on the train of 2 TAU, system needs the modulation coding mode using 16QAM and R=3/4, and guarantees that the SINR that demodulator inputs is 7.0dB.Below, by descriptive system how under the speed per hour of 450kmph, this SINR is reached.

Each transmission, adopt 3 RRH, each RRH to have 4 antennas, each TAU has 2 antennas.Carrier frequency is 2GHz.MMSE receiver is adopted to be used for receiving.Fast for the resource be made up of 3 symbol * 4 subcarriers, channel estimating adopts 4 pilot sub-carriers.

Fig. 5 shows under 3 kinds of transmission algorithms, the impact of RRH covering radius change on systematic function.Wherein, the abscissa in Fig. 5 (a) to Fig. 5 (d) represents the distance between RRH to TAU, and ordinate represents Signal to Interference plus Noise Ratio.Particularly, Fig. 5 (a) represents that RRH radius is 800 meters, and Fig. 5 (b) represents that RRH radius is 1600 meters, and Fig. 5 (c) represents that RRH radius is 4000 meters, and Fig. 5 (d) represents that RRH radius is 8000 meters.In Fig. 5 (a)-Fig. 5 (d), triangle pictorial representation single antenna SingleAnt, round dot represents maximum transmitted beam forming MRTBF, and circle represents the beam forming that ICI of the present invention compensates.Fig. 5 (a) represents particularly,

Single antenna: single antenna sends and receiving system

High specific transmit beamforming: adopt traditional high specific transmit beamforming algorithm

Inter-cell interference cancellation beam forming: adopt the mimo system ICI by transmit beamforming algorithm of the present invention to compensate

When the covering radius of RRH is increased to 8000 meters (Fig. 5 (d)) from 800 meters, for inter-cell interference cancellation beam forming, minimum receiver exports SINR and is reduced to 4.4dB from 7.3dB; For high specific transmit beamforming, minimum receiver exports SINR and is reduced to 3.3dB from 6.2dB.It should be noted that traditional high specific transmit beamforming even also cannot reach target capabilities when RRH covering radius is 800 meters (Fig. 5 (a)).

But by adopting inter-cell interference cancellation beam forming solutions of the present invention, until RRH covering radius is increased in the whole overlay area of 1600m, can ensure that the demodulator of 7.0dB exports SINR.

Be described embodiments of the invention above, but the present invention is not limited to specific system, equipment and concrete agreement, those skilled in that art can make various distortion or amendment within the scope of the appended claims.

The those skilled in the art of those the art can pass through research specification, disclosed content and accompanying drawing and appending claims, understand and implement other changes to the execution mode disclosed.In the claims, word " comprises " element and step of not getting rid of other, and wording " one " does not get rid of plural number.In the present invention, " first ", " second " only represent title, do not represent orbution.In the practical application of invention, the function of the multiple technical characteristics quoted during a part possibility enforcement of rights requires.Any Reference numeral in claim should not be construed as the restriction to scope.

Claims (4)

1., in a base station for providing a method for continuous print broadband connections for the user terminal of high-speed mobile, wherein, multiple Remote Radio Unit is administrative by described base station, and the plurality of Remote Radio Unit shares identical running time-frequency resource, and the method comprises the following steps:

A. current location and the translational speed of described user terminal is obtained;

B. according to described current location and the described translational speed of described user terminal, at least two Remote Radio Unit are selected to be used for the transfer of data of described user terminal;

C. the channel condition information between described user terminal and each described selected Remote Radio Unit is obtained; And

D. according to described channel condition information, united beam shaping is carried out to sent signal, with compensating for doppler frequency deviation,

Wherein, described step D also comprises:

-calculating makes the maximized weight of the Signal to Interference plus Noise Ratio of Received signal strength, united beam shaping is carried out to sent signal by this weight, with compensating for doppler frequency deviation, the Signal to Interference plus Noise Ratio of this Received signal strength represent Received signal strength time constant part power relative to the ratio of the interference power caused because of time varying signal and channel noise power sum.

2. method according to claim 1, wherein, described step B also comprises: the power of closing not selected Remote Radio Unit in the plurality of Remote Radio Unit, or reduces the power of described not selected Remote Radio Unit.

3. method according to claim 1, wherein, described steps A adopts any one realization in following two kinds of modes:

-current location and the translational speed of the described user terminal that described user terminal is reported is obtained by the special channel between described user terminal and described base station; Or

-obtain current location and the translational speed of the described user terminal reported by transducer.

4. method according to claim 1, wherein, described multiple Remote Radio Unit is shared any one in same cell ID, cell special reference, scrambler and cell-specific broadcast channel and cell-specific control channel or is appointed multinomial.