CN100512468C - Multi-media broadcast and multicast service transmitting and receiving method under the time division duplex mode - Google Patents

Abstract

The invention discloses a method for transmitting and receiving multimedia broadcast/multicast service (MBMS) in time-division diplexing (TDD) mode, comprising: transmitting end makes different cells transmit the same MBMS information at the same time; receiving end makes multi-cell combined detection on the received data to restore the original MBMS information. On the one hand, it can avoid the problem of same-frequency interference between MBMS broadcast services in TDD mode; and on the other hand, can provide the combined gain by symbol-level combination; because this mode can transmit high speed MBMS in a time gap, the system utilization ratio is relatively high. And the method can support the MBMS in TDD system in high efficiency.

Description

The method that multimedia broadcast multicast service in TDD mode transmits and receives

Technical field

The present invention relates to wireless communication field, relate in particular to the method that MBMS (multimedia broadcast-multicast service) transmits and receives under a kind of TDD (time division duplex) pattern.

Background technology

The MBMS business is a kind of high speed one way traffic with the transmission of broadcast or multicast form, and it can effectively transmit high-speed multimedia data to a plurality of users simultaneously.MBMS requires this professional user of any activation in the whole sub-district can receive the content that this business is sent out.Because the point-to-multipoint mode (PtM) among the MBMS uses broadcast channel to launch, up do not have a feedback information, the base station can't obtain each user position information, so common Poewr control method can't be implemented, downlink broadcast is launched with fixing power within a certain period of time usually.

Simultaneously, because the data rate of MBMS business is than higher, so the code channel number that MBMS business takies is more than the code channel number of P-CCPCH (Primary Common Control Physical Channel), if time slot power is identical, the solid size road transmitting power of the S-CCPCH of MBMS business (auxiliary publish control physical channel) can be littler than the solid size road transmitting power of P-CCPCH, so, be broadcast channel equally, the coverage of the S-CCPCH channel of carrying MBMS business can be little more a lot of than the coverage of P-CCPCH.

If utilize the method for the transmitting power that increases the MBMS business to remedy above deficiency, so in network, except having increased the signal power of this sub-district, the also corresponding increase of signal power of adjacent sub-district, so, the interference signal of user side increases simultaneously with effective power, and the signal interference ratio of user's received signal does not improve.In this case, be in the middle user in a plurality of sub-districts and can't from multiple interference, obtain correct signal.

At publication number is WO2005048484, name is called have been mentioned a kind of neighbor cell and divides time slot to send the method for same MBMS business in the international patent application of " method and apparatus for combiningmacro-diversity with timeslot re-use in a communication ", can carry out the laggard line data of receiving demodulation to these data at user equipment (UE) like this and merge, can provide macro diversity for the reception of MBMS business like this.But this method can take too much time interval resource, and the cell management more complicated.

For fear of the problems referred to above, must find and a kind ofly can avoid minizone MBMS traffic interference, can receive the method that the MBMS business provides gain for UE again.

Summary of the invention

The technical problem to be solved in the present invention just provides the method that a kind of multimedia broadcast multicast service in TDD mode transmits and receives, raising is to the inter-cell interference suppression ability, and improve the UE termination and receive gain, thereby effectively in the mobile communication system of tdd mode, implement the MBMS business.

In order to solve the problems of the technologies described above, the invention provides the method that a kind of multimedia broadcast multicast service in TDD mode information transmits and receives, comprise the steps:

(1) radio network controller sends simultaneously the MBMS business information of same format, identical content to each base station, and it is all consistent to control business mapping, the modulated process of all sub-districts in each base station;

(2) each base station is carried out spectrum-spreading and scrambling respectively with the MBMS sign level data that obtains, and forms the armed MBMS business datum in each sub-district, and sends this MBMS business datum simultaneously at a time slot;

(3) user equipment (UE) carries out the multi-plot joint detection to the MBMS business datum that receives, and obtains original MBMS information.

Further, described step (2) comprises the steps:

(b1) the base station end of each sub-district carries out business mapping processing respectively to the MBMS business datum of receiving, forms the physical layer bit data flow;

(b2) the physical layer bit data flow is carried out data-modulated, form sign level data, the sign level data of each sub-district is all the same;

(b3) each sub-district utilizes the compound spreading code of this sub-district that described sign level data is carried out spectrum-spreading and scrambling respectively;

(b4) each sub-district sends the same MBMS service data of process spectrum-spreading and scrambling at synchronization.

Further, described step (3) comprises the steps:

(A) user equipment (UE) detects the peripheral cell system information, receives training sequence, spreading code and the scrambling code information of a plurality of sub-districts, receives training sequence according to the training sequence information butt joint and carries out channel estimating, obtains the pairing channel impulse response in each sub-district; The channel impulse response that obtains is sorted by the watt level order;

(B) find out the compound spreading code that the stronger preceding n of channel estimating power organizes the pairing m of a channel estimating code channel, the sytem matrix of forming first group of joint-detection with these compound spreading codes and its pairing channel impulse response, and then find out the compound spreading code of the more weak pairing m of the other n group channel estimating code channel of channel estimating power, the sytem matrix of forming second group of joint-detection, wherein n and m are by total number of users and code channel number decision;

(C) organize interior joint-detection according to the first group system matrix, the signal that obtains is carried out successive interference cancellation, the data that offset are sent into the second group system matrix organize interior joint-detection, the MBMS business datum that detected value and UE receive is carried out successive interference cancellation, data after offseting are carried out again joint-detection in first group the group, obtain MBMS service symbol level and receive data;

(D) if the first group system matrix by forming more than or equal to two cell datas, execution in step (E) then; If the first group system matrix is made up of the single subdistrict data, execution in step (F) then;

(E) the MBMS service symbol level that obtains being received data merges;

(F) the MBMS service symbol level that obtains is received data and carry out demodulation, decoding, obtain original MBMS service bits information.

One aspect of the present invention can be avoided the problem of co-channel interference between the MBMS broadcasting service under the tdd mode, can utilize symbol level to merge in addition and provide to merge gain; Because this mode can send MBMS business at a high speed in a time slot, so system availability is than higher.Adopt method of the present invention, can in the TDD system, support the MBMS business efficiently.

Description of drawings

Fig. 1 is the network figure of application example of the present invention;

Fig. 2 is the base station end group tape handling flow chart of i sub-district of application example of the present invention;

Fig. 3 is the UE end group tape handling flow chart of application example of the present invention.

Embodiment

Because the TDD system distributed channel resource according to the time, each minizone is a synchro system, method of the present invention is exactly to utilize the synchronizing characteristics of TDD system, make different sub-districts send identical MBMS business information at synchronization, the UE end can receive the different copies from the same MBMS business information of different districts in this time like this, these copies are carried out input and merge processing at the UE end, thereby obtain original MBMS business information data.

The embodiment of the invention comprises the steps:

Step 1, under a RNC (radio network controller), there are a plurality of base stations, RNC sends the MBMS business datum of same format, identical content simultaneously to each base station, and business mapping, the modulated process of controlling all sub-districts in each base station are all consistent, and above-mentioned all sub-districts of the professional emission of this MBMS that just lets on are just the same at symbol level in the MBMS business datum that synchronization sends;

Step 2, each sub-district is carried out spectrum-spreading and scrambling respectively with the MBMS sign level data that step 1 obtains, and forms each sub-district data to be launched, and finally these sub-districts send this MBMS business datum simultaneously at a time slot;

Step 3, the receiving terminal user equipment (UE) detects the peripheral cell system information, obtain training sequence, spreading code and the scrambling code information of a plurality of sub-districts simultaneously, at first receive training sequence and carry out channel estimating, obtain the pairing channel impulse response in each sub-district according to the training sequence information butt joint; The channel impulse response that obtains is sorted by the watt level order;

Step 4, the channel impulse response that step 3 is obtained, find out the compound spreading code of the stronger pairing m of the preceding n group channel estimating code channel of channel estimating power, the sytem matrix of forming first group of joint-detection with these compound spreading codes and its pairing channel impulse response, and then find out the compound spreading code of the more weak pairing m of the other n group channel estimating code channel of channel estimating power, form the sytem matrix of second group of joint-detection according to the method for front, wherein n and m are by total number of users and code channel number decision;

Step 5, at first organize interior joint-detection according to the first group system matrix, the signal that obtains is carried out successive interference cancellation, the data that offset are sent into the second group system matrix organize interior joint-detection, detected value and UE reception data are carried out successive interference cancellation, data after offseting are carried out again joint-detection in first group the group, finally obtain detecting dateout;

Step 6 is if the first group system matrix then carries out the processing of step 7 by forming more than or equal to two cell datas; If the first group system matrix is made up of the single subdistrict data, then carry out the processing of step 8;

Step 7 because sytem matrix is made up of a plurality of sub-districts, so detected symbol data is the symbol data of a plurality of sub-districts, merges these sign level data in this step;

Step 8 receives data to the MBMS service symbol level that obtains and carries out demodulation, decoding from top step, obtain original MBMS service bits information.

Be that example is carried out concrete description with the 64kbpsMBMS business in the TD-SCDMA communication system below:

As shown in Figure 1, in the TD-SCDMA system, a RNC controls a plurality of base stations, a base station can be divided into a plurality of sub-districts, should use in the example, RNC transmits identical MBMS business data flow to each sub-district, and it is just the same in the business mapping and the modulation system of same time slot to control each sub-district, spectrum-spreading and scrambling is carried out to these data respectively in each sub-district then, and then each sub-district sends the MBMS business datum simultaneously; At UE end, by detecting all system information of subdistricts, then according to the present invention the symbol level merge algorithm to data detect, demodulation, decoding, finally obtain original MBMS business datum.

As shown in Figure 2, should utilize the TD-SCDMA system with the transmitting terminal of example is the characteristics of synchro system, allows a plurality of sub-districts launch identical MBMS business datum d at one time _MBMS

Step 101, base station receive the MBMS business data flow from RNC, and the base station end of each sub-district carries out the business mapping respectively to these data to be handled, and forms the physical layer bit data flow;

Step 102 is carried out data-modulated to bit data flow, forms sign level data data ₁, the sign level data of each sub-district is all the same, that is:

data＝data ₁＝data ₂＝...＝data _n

Wherein on behalf of an object UE, n can receive the number of the sub-district of certain strength signal;

Step 103, i sub-district according to the compound spreading code that utilizes this sub-district to sign level data data ₁Carry out the spectrum-spreading and scrambling operation, that is:

S _i＝data ₁*C _i

C wherein _iIt is the professional corresponding compound spreading code of MBMS of i sub-district.

Each sub-district sends these same MBMS service datas through Base-Band Processing at synchronization.

As shown in Figure 3, be the UE end group tape handling flow chart of application example of the present invention.At receiving terminal, the received signal of UE can be expressed as:

$R=\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{S}_j\·H_j=\mathrm{data}\·\underset{j=1}{\overset{n}{\mathrm{\Σ}}}(C_j\·H_j)=\mathrm{data}\·A$

Wherein $A=\underset{j=1}{\overset{n}{\mathrm{\Σ}}}(C_j\·H_j)$ Be the hybrid system matrix that receiving terminal shows, H _jBe the signal of j sub-district actual arrive that UE experienced channel impulse response.

Step 201, UE is at first according to the training sequence M of each system information of subdistricts to receiving _RCarry out channel estimating, the basic training sequences of establishing i sub-district is M _i, can obtain each sub-district estimated channel impulse response according to channel estimation method:

Wherein ${\hat{H}}_i=[{\hat{h}}_{i1},{\hat{h}}_{i2},...,{\hat{h}}_{1w}],$ W represents that channel estimation window is long.Above-mentioned channel estimation value resequenced according to power obtain

If $P_j=\underset{i=1}{\overset{w}{\mathrm{\Σ}}}{\hat{h}}_{\mathrm{ji}}^{\′}\·{\left({\hat{h}}_{\mathrm{ji}}^{\′}\right)}^{*},$ So P ₁P ₂... P _n

Step 202, because be the 64kbps business, in the TD-SCDMA system, this business takies 8 Code Channels of a time slot, so i corresponding i estimated channel impulse response of user

The compound spreading code of simultaneously corresponding 8 Code Channels is designated as C _i=[c _I1, c _I2... .c _I8], the channel impulse response of two sub-district correspondences that the selection power ratio is bigger

And compound spread spectrum codes C ₁, C ₂, form sytem matrix A ₁Then find the channel impulse response of two time big sub-district correspondences of power again

And compound spread spectrum codes C ₃, C ₄, form sytem matrix A ₂If the sub-district number equals 3, sytem matrix A then ₂By And C ₃Constitute;

Step 203 is according to the first group system matrix A ₁Carry out joint-detection to receiving data e, obtain detecting output soft symbol data data ₁, to data ₁Carry out hard decision, the bit signal that obtains estimating

Make its received signal of regenerating $e_1,e_1=A_1\·{\hat{d}}_1^{\′},$ From received signal, eliminate e ₁, obtain e ₂=e-e ₁With A ₂Same e ₂Carry out joint-detection, obtain exporting soft symbol data data ₂, to data ₂Carry out hard decision, the bit signal that obtains estimating Make its received signal e that regenerates ₃, $e_3=A_2\·{\hat{d}}_2^{\′},$ From received signal, eliminate e ₃, obtain e ₄=e-e ₃At last with A ₁Same e ₄Carry out final joint detection algorithm, obtain soft symbol information data _SoftWherein, soft symbol is meant the data of joint-detection output, and hard decision is meant data to be demodulated and particular value are compared, similar to particular value this value that just is judged to be.

Step 204 is judged soft symbol information, is made up of the data of a plurality of sub-districts if detect the soft symbol information that obtains, and then execution in step 205; Just be made up of the data of single subdistrict if detect the soft symbol information that obtains, then execution in step 206;

Step 205 is because data _SoftThe symbolic information that comprises 2 sub-districts, that is: data _{Cell_1}, i=1,2, then the symbol data with these sub-districts merges, promptly

C wherein _iBe the weighted value that obtains according to the channel impulse response watt level, by c1=P1/ (P1+P2), c2=P2/ (P1+P2) obtains, and P1, P2 are channel impulse response power;

Step 206 is with data _EstimateCarry out demodulation, decoded operation, obtain the professional initial data of final MBMS: ${\hat{d}}_{\mathrm{MBMS}}.$

In sum, one aspect of the present invention can be avoided the problem of co-channel interference between the MBMS broadcasting service under the tdd mode, can utilize symbol level to merge in addition and provide to merge gain; Because this mode can send MBMS business at a high speed in a time slot, so system availability is than higher.Adopt method of the present invention, can in the TD-SCMDA system, support the MBMS business efficiently.

Claims (3)

1. the method that multimedia broadcast multicast service in TDD mode information transmits and receives comprises the steps:

(1) radio network controller sends simultaneously the MBMS business information of same format, identical content to each base station, and it is all consistent to control business mapping, the modulated process of all sub-districts in each base station;

(2) each base station is carried out spectrum-spreading and scrambling respectively with the MBMS sign level data that obtains, and forms the armed MBMS business datum in each sub-district, and sends this MBMS business datum simultaneously at a time slot;

(3) user equipment (UE) carries out the multi-plot joint detection to the MBMS business datum that receives, and obtains original MBMS information.

2. method according to claim 1 is characterized in that, described step (2) comprises the steps:

(b1) the base station end of each sub-district carries out business mapping processing respectively to the MBMS business datum of receiving, forms the physical layer bit data flow;

(b2) the physical layer bit data flow is carried out data-modulated, form sign level data, the sign level data of each sub-district is all the same;

(b3) each sub-district utilizes the compound spreading code of this sub-district that described sign level data is carried out spectrum-spreading and scrambling respectively;

(b4) each sub-district sends the same MBMS service data of process spectrum-spreading and scrambling at synchronization.

3. method according to claim 1 is characterized in that, described step (3) comprises the steps:

(A) user equipment (UE) detects the peripheral cell system information, receives training sequence, spreading code and the scrambling code information of a plurality of sub-districts, receives training sequence according to the training sequence information butt joint and carries out channel estimating, obtains the pairing channel impulse response in each sub-district; The channel impulse response that obtains is sorted by the watt level order;

(B) find out the compound spreading code that the stronger preceding n of channel estimating power organizes the pairing m of a channel estimating code channel, the sytem matrix of forming first group of joint-detection with these compound spreading codes and its pairing channel impulse response, and then find out the compound spreading code of the more weak pairing m of the other n group channel estimating code channel of channel estimating power, the sytem matrix of forming second group of joint-detection, wherein n and m are by total number of users and code channel number decision;

(C) organize interior joint-detection according to the first group system matrix, the signal that obtains is carried out successive interference cancellation, the data that offset are sent into the second group system matrix organize interior joint-detection, the MBMS business datum that detected value and UE receive is carried out successive interference cancellation, data after offseting are carried out again joint-detection in first group the group, obtain MBMS service symbol level and receive data;

(D) if the first group system matrix by forming more than or equal to two cell datas, execution in step (E) then; If the first group system matrix is made up of the single subdistrict data, execution in step (F) then;

(E) the MBMS service symbol level that obtains being received data merges;

(F) the MBMS service symbol level that obtains is received data and carry out demodulation, decoding, obtain original MBMS service bits information.

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