CN102195915A - Cooperative multi-point transmission method and equipment - Google Patents

Abstract

The invention discloses a cooperative multi-point transmission method and equipment. The method comprises the following steps of: weighting a data signal by using a phase adjusting value, so that a mobile terminal can combine data signals received from a plurality of cooperative sites to form a combination signal with the maximum signal intensity; and transmitting the weighted data signal to the mobile terminal. By adopting the technical scheme, the mobile terminal can constantly obtain enhanced data streams.

Description

A kind of collaborative point transmitting method and equipment thereof

Technical field

Embodiments of the present invention are broadly directed to the communications field, more specifically, relate to a kind of collaborative point transmitting method and equipment thereof.

Background technology

A technology that gets a good chance of in the Long Term Evolution (LTE-Advanced) that collaborative multiple spot (CoMP) transmission is the advanced person can be used for reducing effectively presence of intercell interference (ICI), improves the covering of cell edge, increases the throughput of system.Joint transmission (JT) is one of CoMP scheme, and in this scheme, data flow is shared in the collaborative collection of CoMP, carries out Combined Treatment by a plurality of sub-districts, and sends to a plurality of users.The user merges after receiving signal, to improve signal power and to reduce presence of intercell interference.

Fig. 6 shows the example of a such multi-site joint transmission.In Fig. 6, collaborative by eNB1, eNB2 and eNB3 for the UE1 among the eNB1 provides service, eNB1, eNB2 and eNB3 are called collaborative site.Use according to the selected transmission precoder of local channel state (CSI) and respectively the data flow from each collaborative site is weighted from each collaborative site to UE1.Suppose that the corresponding precoder of eNB1, eNB2 and eNB3 and UE1 is respectively W11, W12, W13, if be identical from each collaborative site to the data flow that UE1 sends, then the signal that receives of UE1 can be expressed as:

Y＝(H ₁₁W ₁₁+H ₁₂W ₁₂+H ₁₃W ₁₃)X+NI

Wherein, X is that NI is interference and the noise of introducing in the process of transmitting from the data flow of collaborative site before the precoding that UE1 sends.

In above-mentioned equation, have different phase informations from the signal of different collaborative site, therefore, the mixed channel H of equivalence ₁₁W ₁₁+ H ₁₂W ₁₂+ H ₁₃W ₁₃The data flow that always at any time can both be enhanced not.

Summary of the invention

Embodiments of the present invention have proposed a kind of collaborative point transmitting method and equipment thereof, with the data flow that is enhanced consistently.

According to an aspect of the present invention, a kind of collaborative point transmitting method is provided, comprise and use phase adjustment value that data-signal is weighted processing, so that described portable terminal can merge the data-signal that receives from a plurality of collaborative site, form combined signal with maximum signal; To send to portable terminal through the data-signal of weighted.

According to a further aspect in the invention, a kind of collaborative point transmitting method is provided, comprise reception and merging data-signal from a plurality of collaborative site, wherein, described data-signal uses corresponding phase adjustment value to carry out weighted in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity.

In accordance with a further aspect of the present invention, a kind of base station is provided, comprise the phase weighting unit, be used to use phase adjustment value that data-signal is weighted processing, so that described portable terminal can merge the data-signal that receives from a plurality of base stations, form combined signal with maximum signal; The base station transceiver unit is used for the data-signal through weighted is sent to portable terminal.

According to another aspect of the invention, a kind of portable terminal is provided, comprise: the terminal Transmit-Receive Unit, be used to receive and merge data-signal from a plurality of collaborative site, wherein, described data-signal uses corresponding phase adjustment value to carry out weighted in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity.

According to another aspect of the invention, provide a kind of cooperative multipoint transmission system, comprised a plurality of above-mentioned base stations and portable terminal, and be used for the backhaul of communicating by letter between the described base station.

According to the disclosed technical scheme of embodiments of the invention, make behind the collaborative site institute data signals transmitted arrival portable terminal, merge the signal that obtains through portable terminal and can reach maximum signal strength signal intensity, thereby obtained the data flow that strengthens consistently.

Description of drawings

In conjunction with the accompanying drawings embodiments of the invention are described in detail, can understand the present invention better, wherein:

Fig. 1 shows the applied exemplary cell of the embodiment of the invention and disposes and clustering architecture;

Fig. 2 shows the transmission system of the embodiment of the invention;

Fig. 3 shows the architecture of base station block diagram of the embodiment of the invention;

Fig. 4 shows the structured flowchart of the portable terminal of the embodiment of the invention;

Fig. 5 shows the method flow diagram of the embodiment of the invention;

Fig. 6 shows the transmission system of prior art scheme.

Embodiment

To a preferred embodiment of the present invention will be described in detail, having omitted in the description process is unnecessary details and function for the present invention with reference to the accompanying drawings, obscures to prevent that the understanding of the present invention from causing.

Fig. 1 shows applied a kind of cell deployment of the embodiment of the invention and clustering architecture.In structure shown in Figure 1, always have 7 websites (shown in the round dot among Fig. 1), each website has the sub-district of 3 rhombuses.Three neighbor cells from different websites form bunch (shown in the shadow region among Fig. 1).Joint transmission and combined dispatching carry out in each bunch.It should be appreciated by those skilled in the art that structure illustrated in fig. 1 only is to be used for the convenient technical scheme of clearly setting forth the embodiment of the invention and being proposed, rather than to the restriction of application scenarios of the present invention.From next can clearly be seen that the detailed description to embodiment of the present invention, the method and apparatus that embodiment of the present invention proposed is applicable to any cell deployment and clustering architecture that relates to a plurality of websites.

Embodiments of the invention have proposed a kind of transmission system, as shown in Figure 2, and a plurality of base stations, portable terminal and the backhaul that will describe below this transmission system comprises.Be to be appreciated that, though only schematically show three base station eNB 1, eNB2 and eNB3 and a mobile terminal UE 1 among Fig. 2, yet in the network design of reality, more or less base station and more portable terminal can be arranged, and the communication between each base station also can be undertaken by alternate manner.

Embodiments of the invention have proposed a kind of base station.As shown in Figure 3, this base station comprises phase weighting unit 320, is used for data-signal is carried out phase weighting; Base station transceiver unit 330 is used for the data-signal behind the phase weighting is treated to the signal that is fit to the spacing wireless transmission, and without limitation, the function of base station transceiver unit 330 can comprise digital to analog conversion, up-conversion, power amplification etc.

This base station also can comprise optimum precoder 310, is used for before data-signal is carried out phase weighting data-signal being carried out optimum precoding, the processing such as can pass through coding in advance, modulate and interweave of the data-signal of importing optimum precoder.

Base station transceiver unit 330 also sends downlink reference signal and mobile terminal receive to the feedback of downlink reference signal to portable terminal, without limitation, can send by the mode of broadcasting.This base station also can comprise information extraction unit 340, and the feedback that is used for receiving from base station transceiver unit 330 is extracted optimum phase adjusted value information.Phase weighting unit 320 is used for being configured according to this optimum phase adjusted value information, and it is weighted with the signal of optimum phase adjusted value to follow-up transmission.The optimum phase adjusted value information here can be optimum phase adjusted value itself, also can be can unique expression optimum phase adjusted value any numerical value.

In addition, in from the feedback of portable terminal, can also comprise optimum precoding information at this base station.

Embodiments of the invention have also proposed a kind of portable terminal.As shown in Figure 4, this portable terminal comprises terminal Transmit-Receive Unit 410, is used for the downlink reference signal that each collaborative base station sends is carried out radio frequency processing.Without limitation, the function of terminal Transmit-Receive Unit 410 can comprise that low noise amplifies (LNA), down-conversion, analog to digital conversion or the like.Phase calculation unit 420, be used for feeding back to corresponding collaborative base station according to the calculated signals optimum phase adjusted value after handling and by terminal Transmit-Receive Unit 410, here, the optimum phase adjusted value is the data flow phase adjustment value that makes each collaborative base station of the wireless signal strength maximum that receives.

Portable terminal also comprises precoding determining unit 440, is used for according to the optimum pre-coding matrix of the calculated signals after 410 processing of terminal Transmit-Receive Unit at each base station, and feeds back to corresponding base station by terminal Transmit-Receive Unit 410.

Terminal Transmit-Receive Unit 410 also is used for the data-signal that each collaborative base station sends is carried out radio frequency processing, and wherein, this data-signal has passed through phase weighting on each collaborative base station.This portable terminal also comprises demodulating unit 430, is used for the data of coming self terminal Transmit-Receive Unit 410 are carried out the signal baseband operation, as demodulation, deinterleaving, decoding or the like.

Though above with the formal description of the functional module of separating the base station and the portable terminal of the embodiment of the invention, but each assembly shown in Fig. 3 or Fig. 4 can realize with a plurality of devices in actual applications, and a plurality of assemblies that illustrate also can be integrated in chip piece or the equipment in actual applications.This base station and portable terminal also can comprise any unit and the device that is used for other purpose.

Below in conjunction with Fig. 5 the function of Fig. 3 and equipment shown in Figure 4 is described in detail.

In down link (DL) multi-site cooperative transmission schemes, one or more presence of intercell interference becomes the useful signal that is used to increase signal power.For example in Fig. 6, provide service to UE1 by three adjacent eNB.UE1 can be according to measuring DL channel condition information (CSI) from the DL reference signal of three eNB respectively, thereby and determine and optimum precoder that corresponding CSI is complementary, the same with example at Fig. 6, the optimum precoder of working in coordination with eNB can be expressed as W11, W12 and W13 respectively.Different channels from different e NB has different phase directionals, selects suitable phase directional adjustment for each collaborative site in an embodiment of the present invention and can strengthen the intensity of the signal after the merging.

As benchmark, the angle of supposing two data flow execution of phase correction of eNB2 is θ with the direction of the data flow of serving BS eNB1 ₁And θ ₂, and the angle of two data flow execution of phase correction of hypothesis eNB2 is θ ₃And θ ₄

As shown in Figure 5, in step 510,310 pairs of data-signals of optimum precoder among the collaborative eNB carry out precoding, in step 520, data-signal behind the 320 pairs of codings in phase weighting unit is introduced different phasing matrixes, and via data-signal and downlink reference signal behind the base station transceiver unit 330 transmission phase weightings.In step 530,410 pairs of data-signals of the terminal Transmit-Receive Unit of UE1 and downlink reference signal receive and detect, and wherein, the data-signal that receives can be expressed as:

$Y=(H_{11}{W}_{11}+H_{12}{W}_{12}{M}_{\mathrm{\θ}}^2+H_{13}{W}_{13}{M}_{\mathrm{\θ}}^3)X+\mathrm{NI}---\left(1\right)$

Wherein, the phasing matrix of eNB2 is $M_{\mathrm{\θ}}^2=\left(\begin{array}{cc}{e}^{j{\mathrm{\θ}}_1}& 0\\ 0& e^{j{\mathrm{\θ}}_2}\end{array}\right)$

The phasing matrix of eNB3 is $M_{\mathrm{\θ}}^3=\left(\begin{array}{cc}{e}^{j{\mathrm{\θ}}_3}& 0\\ 0& e^{j{\mathrm{\θ}}_4}\end{array}\right)$

In order to select optimum phase adjustment value, in step 540, according to formula (2), phase calculation unit 420 is found the solution maximum according to the capacity that the downlink reference signal that receives is combined signal, thereby obtains the optimum phase adjusted value:

$\underset{\left\{{\mathrm{\θ}}_i\right\}}{\arg \max }\underset{k}{\mathrm{\Σ}}{\left|\right|H_{11}\left(k\right)W_{11}+H_{12}\left(k\right)W_{12}\left(\begin{array}{cc}{e}^{j{\mathrm{\θ}}_1}& 0\\ 0& e^{j{\mathrm{\θ}}_2}\end{array}\right)+H_{13}\left(k\right)W_{13}\left(\begin{array}{cc}{e}^{j{\mathrm{\θ}}_3}& 0\\ 0& e^{j{\mathrm{\θ}}_4}\end{array}\right)\left|\right|}^2---\left(2\right)$

Wherein, the amplitude of acquiescence downlink reference signal is 1.Wherein, H ₁₁(k) expression H ₁₁Channel value on k frame or k carrier wave, but its value actual measurement obtains.K is time domain or frequency domain width, and the span of k can be several frames on the time domain, also can be tens subcarriers on the frequency domain, and preferably, the span of k should not be too big.

When equation (2) when obtaining maximum, can think to have obtained each optimum phase adjusted value.Preferably, resulting optimum phase adjusted value when solution formula (2), can from one group of following phase angle, select:

${\mathrm{\θ}}_i=\frac{2\mathrm{\π}(n-1)}{N},i=1,\·\·\·,4,n=1,\·\·\·,N$

Wherein, N is the granularity of phasing.

If N is set to 2, optionally the phase angle has two, promptly+1, and-1}, then each phasing needs the feedback of 1 bit.

If N is set to 4, optionally the phase angle has four, promptly Then each phasing needs the feedback of 2 bits.

If N is set to 2 ^m, then each phasing needs the feedback of m bit.

Phase calculation unit 420 returns optimum phase adjusted value feedback information to each collaborative eNB by terminal radio frequency unit 410, optimum phase adjusted value information can be optimum phase adjusted value itself, also can be can unique expression optimum phase adjusted value any numerical value.

At user side, have two kinds of feedbacks can determine to send weighted information (pre-coding matrix index and/or optimum phase adjusted value):

One, determine optimum precoder, and the pre-coding matrix index (PMI) of correspondence is fed back to its service eNB, by backhaul PMI is sent to other collaborative eNB by service eNB then with the local DL channel condition information (CSI) of coupling from collaborative eNB.Each collaborative eNB uses pre-coding matrix separately in step 510 data-signal to be carried out precoding.Wherein, optimum precoder is to find the solution respectively according to the channel of each sub-district to obtain, and its concrete method for solving is known to those skilled in the art, does not repeat them here.

Its two, if use the phasing algorithm further to strengthen the signal strength signal intensity that receives, only need a spot of added bit to come the adjustment of feedback phase direction.

After the base station transceiver unit 330 of corresponding eNB receives feedback information, in step 550, information extraction unit 340 extracts optimum phase adjusted value information and/or pre-coding matrix index, thereby, optimum precoder unit 310 uses pre-coding matrix index that data-signal is carried out precoding, and phase weighting unit 320 utilizes optimum phase adjusted value information that the data-signal through precoding is weighted.Behind the eNB and UE1 Transmit-Receive Unit 330,410 processing separately of data-signal after this weighting via correspondence, in step 560, carry out base band signal process, as demodulation, deinterleaving and decoding or the like by demodulating unit 430.

What should be noted that is, the transmission of downlink reference signal and the transmission of data-signal do not have necessary relation, though therefore above description indefiniteness ground with reference to figure 4 is with the generation of the transmission of data-signal and weighted information (pre-coding matrix index and/or optimum phase adjusted value) and be delivered in the flow process and narrate, yet those skilled in the art will be appreciated that, these two processing can be independently, the generation and the transmission that are weighted information can be before data, among or any stage afterwards carry out, also can when not having data, realize the generation and the transmission of weighted information.

Multi-site joint transmission that the embodiment of the invention the proposes systematic function in conjunction with phasing is assessed in the emulation of following using system level.

System consumption and policy parameter are as follows:

The rhombus sector

Transmitter: 4 * 2CL-MIMO

Receiver: MMSE detector

Do not adopt HARQ

11 MCS types, target BLER=0.01

Equitable proportion (PF) scheduler

Channel estimation errors=3dB

Cell Edge User threshold value :-1dB

Multi-site joint transmission scheme based on Single User MIMO (SU-MIMO)

The phasing of 1 bit feedback

Two flow transmission

PMI based on code book selects

The system-level simulation result of table 1

Transmission plan	Sub-district average throughput (kbps)	5% user throughput (kbps)
			SU-MIMO	9439(1.00)	177.4(1.00)
The multi-site joint transmission	9477(1.00)	224.1(1.26)
			Multi-site joint transmission (having phasing)	9413(1.00)	244.5(1.38)

Table 1 shows simulation result, compares with single sub-district SU-MIMO as can be seen, the cell edge throughput gain of (=(224.1-177.4)/177.4) that the multi-site transmission plan obtains 26%, and do not lose average throughput.When additional when using the phasing algorithm, multi-site joint transmission scheme can also obtain 12% more, and (=(244.5-177.4)/177.4-26%) edge cell user throughput gains and loses the sub-district average throughput hardly.Further emulation also shows, when granularity (N) increase of phasing, can also further improve the systematic function of multi-site joint transmission.

Those skilled in the art should be easy to recognize, can realize the different step of said method by programmed computer.At this, some execution modes comprise equally machine readable or computer-readable program storage device (as, digital data storage medium) and the coding machine can carry out or the executable program command of computer, wherein, some or all steps of said method are carried out in this instruction.For example, program storage device can be digital storage, magnetic storage medium (as Disk and tape), hardware or the readable digital data storage medium of light.Execution mode comprises the programmed computer of the described step of carrying out said method equally.

Description and accompanying drawing only illustrate principle of the present invention.Therefore should be appreciated that those skilled in the art can advise different structures,, embodied principle of the present invention and be included within its spirit and scope though these different structures are not clearly described herein or illustrated.In addition, all examples of herein mentioning mainly only are used for teaching purpose clearly helping the design of reader understanding's principle of the present invention and promotion this area that the inventor was contributed, and should be interpreted as not being the restriction to these specific examples of mentioning and condition.In addition, all statement and specific examples thereof of mentioning principle of the present invention, aspect and execution mode comprise its equivalent interior herein.

Top description only is used to realize embodiments of the present invention; it should be appreciated by those skilled in the art; the any modification or partial replacement that is not departing from the scope of the present invention; all should belong to claim of the present invention and come restricted portion; therefore, protection scope of the present invention should be as the criterion with the protection range of claims.

Claims (11)

1. collaborative point transmitting method comprises:

Use phase adjustment value that data-signal is weighted processing,, form combined signal with maximum signal so that described portable terminal can merge the data-signal that receives from a plurality of collaborative site;

To send to portable terminal through the data-signal of weighted.

2. method according to claim 1 also comprises:

Before described use phase adjustment value is weighted data-signal, described data-signal is carried out optimum precoding.

3. method according to claim 1 and 2 also comprises:

Send downlink reference signal to described portable terminal;

Receive the feedback of described portable terminal to described downlink reference signal, and the pre-coding matrix index that therefrom extracts described phase adjustment value and/or be used to carry out optimum precoding.

4. collaborative point transmitting method comprises:

Receive and merge data-signal from a plurality of collaborative site, wherein, described data-signal uses corresponding phase adjustment value to carry out weighted in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity.

5. method according to claim 4 also comprises:

Receive the downlink reference signal that described a plurality of collaborative site sends;

According to described downlink reference signal, determine in described a plurality of collaborative site each phase adjustment value and/or be used for the pre-coding matrix index that carries out optimum precoding in described a plurality of collaborative site;

Described phase adjustment value and/or described pre-coding matrix index are fed back to described a plurality of collaborative site.

6. base station comprises:

The phase weighting unit is used to use phase adjustment value that data-signal is weighted processing, so that described portable terminal can merge the data-signal that receives from a plurality of collaborative site, forms the combined signal with maximum signal;

The base station transceiver unit is used for the data-signal through weighted is sent to portable terminal.

7. base station according to claim 6 also comprises:

Optimum precoding unit is used for before described use phase adjustment value is weighted data-signal described data-signal being carried out optimum precoding.

8. according to claim 6 or 7 described base stations, wherein, described base station transceiver unit also is used for sending downlink reference signal to described portable terminal;

Described base station also comprises:

Information extraction unit is used to receive the feedback of described portable terminal to described downlink reference signal, and the pre-coding matrix index that therefrom extracts described phase adjustment value and/or be used to carry out optimum precoding.

9. portable terminal comprises:

The terminal Transmit-Receive Unit, be used to receive and merge data-signal from a plurality of collaborative site, wherein, described data-signal uses corresponding phase adjustment value to carry out weighted in each of described a plurality of collaborative site, so that the signal after merging has maximum signal strength signal intensity.

10. portable terminal according to claim 9, wherein, described terminal Transmit-Receive Unit also is used to receive the downlink reference signal that described a plurality of collaborative site sends;

Described portable terminal also comprises:

The phase place determining unit is used for according to described downlink reference signal, determines at each phase adjustment value in described a plurality of collaborative site; And/or

The precoding determining unit is used for according to described downlink reference signal, is identified for the pre-coding matrix index that carries out optimum precoding in described a plurality of collaborative site.

11. a cooperative multipoint transmission system comprises according to each described base station in the claim 6 to 8, according to claim 9 or 10 described portable terminals and be used for the backhaul of communicating by letter between the described base station.

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