(19)
(11)EP 2 230 807 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
11.12.2019 Bulletin 2019/50

(21)Application number: 10157008.3

(22)Date of filing:  19.03.2010
(51)International Patent Classification (IPC): 
H04L 25/03(2006.01)
H04L 5/00(2006.01)

(54)

Apparatus and method for reducing inter-cell interference in multiple input multiple output system

Vorrichtung und Verfahren zur Verringerung der Zwischenzellinterferenz in MIMO-Systemen

Appareil et procédé pour réduire l'interférence intracellulaire dans un système d'entrée/sortie multiples


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO SE SI SK SM TR

(30)Priority: 20.03.2009 KR 20090024136

(43)Date of publication of application:
22.09.2010 Bulletin 2010/38

(73)Proprietor: Samsung Electronics Co., Ltd.
Suwon-si, Gyeonggi-do, 443-742 (KR)

(72)Inventors:
  • Kim, Eun-Yong
    Gyeonggi-do (KR)
  • Kim, Yu-Seok
    Seoul (KR)
  • Lee, Sang-Min
    Seoul (KR)
  • Ko, Eun-Seok
    Gyeonggi-do (KR)

(74)Representative: HGF Limited 
Saviour House 9 St. Saviourgate
York YO1 8NQ
York YO1 8NQ (GB)


(56)References cited: : 
  
  • SHKUMBIN HAMITI: "THE DRAFT IEEE 802.16m System Description Document. IEEE 802.16M-08/003R7", IEEE 802.16 BROADBAND WIRELESS ACCESS WORKING GROUP, IEEE 802.16 BROADBAND WIRELESS ACCESS WORKING GROUP, USA , vol. IEEE 802.16M-08/003R7, no. IEEE 802.16M-08/003R7 7 February 2009 (2009-02-07), pages 1-171, XP008161571, Retrieved from the Internet: URL:http://ieee802.org/16/tgm/docs/80216m- 08_003r7.zip
  • LG ELECTRONICS: "UE Measurement and Feedback for DL CoMP", 3GPP DRAFT; R1-091193 LGE_COMP UE_MEASUREMENT_FEEDBACK, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, no. Seoul, Korea; 20090318, 18 March 2009 (2009-03-18), XP050338810, [retrieved on 2009-03-18]
  • QUALCOMM EUROPE: "Signaling for spatial coordination in DL CoMP", 3GPP DRAFT; R1-090867, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, no. Athens, Greece; 20090204, 4 February 2009 (2009-02-04), XP050318716, [retrieved on 2009-02-04]
  • SAMSUNG: "Further discussion on Inter-Cell Interference Mitigation through Limited Coordination", 3GPP DRAFT; R1-083569 FURTHER DISCUSSION ON COMP, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, no. Prague, Czech Republic; 20080925, 25 September 2008 (2008-09-25), XP050316931, [retrieved on 2008-09-25]
  • "Views on Coordinated Multipoint Transmission/Reception in LTE-Advanced", 3GPP DRAFT; R1-084252 COMP, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, vol. RAN WG1, no. Prague, Czech Republic; 20081110 - 20081114, 4 November 2008 (2008-11-04), XP050597118, [retrieved on 2008-11-04]
  • QUALCOMM EUROPE: "Impact of Downlink CoMP on the Air Interface", 3GPP DRAFT; R1-090366, 3RD GENERATION PARTNERSHIP PROJECT (3GPP), MOBILE COMPETENCE CENTRE ; 650, ROUTE DES LUCIOLES ; F-06921 SOPHIA-ANTIPOLIS CEDEX ; FRANCE, no. Ljubljana; 20090108, 8 January 2009 (2009-01-08), XP050318270, [retrieved on 2009-01-08]
  • "Proposed Text of MIMO for the IEEE 802.16m Amendment ; C80216m-09_0513r2", IEEE DRAFT; C80216M-09_0513R2, IEEE-SA, PISCATAWAY, NJ USA, vol. 802.16m, 11 March 2009 (2009-03-11), pages 1-36, XP017611801, [retrieved on 2009-03-12]
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

BACKGROUND OF THE INVENTION


1. Field of the Invention:



[0001] The present invention relates to a Multiple Input Multiple Output (MIMO) system. More particularly, the present invention relates to an apparatus and method for reducing an inter-cell interference in a MIMO system.

2. Description of the Related Art:



[0002] Recently, research on a technique for controlling an inter-cell interference through inter-Base Station (BS) coordination has been conducted. The inter-BS coordination technique is called Coordinated Multiple Point Transmission/Reception (CoMP) in the 3rd Generation Partnership Project (3GPP) Long Term Evolution-Advanced (LTE-A) standard and is called Multi-cell Multiple Input Multiple Output (MIMO) in the Institute of Electrical and Electronics Engineers (IEEE) standard 802.16m. Although the following description is given of the CoMP technique with reference to the 3GPP standardization group, it is also applicable to the multi-cell MIMO technique of the IEEE standard 802.16m.

[0003] The CoMP technique is divided into a Coordinated scheduling and/or Beamforming (CB) technique and a Joint Processing/transmission (JP) technique. Similar to a conventional single-cell MIMO technique, the CB technique transmits traffic data for one User Equipment (UE) from one transmitting node (i.e., a BS or a cell). Thus, the CB technique does not require inter-cell packet sharing and cannot use a Signal-to-Noise Ratio (SNR) enhancement technique. On the other hand, the JP technique transmits traffic data for one UE from two or more transmitting nodes. Thus, the JP technique can enhance an SNR by means of the SNR enhancement technique and requires inter-cell packet sharing.

[0004] An example of the CB technique is a Precoding Matrix Information (PMI) restriction technique. In the PMI restriction technique, a UE located at a cell boundary requests a serving BS to prevent a precoding vector from being used by an adjacent BS if the UE receives a strong interference from an adjacent cell due to the use of a precoder between adjacent cells. The adjacent BS does not use the precoding vector according to the request. Accordingly, the inter-cell interference decreases and thus the PMI restriction technique can enhance an SNR.

[0005] Examples of the JP technique include a Macro diversity technique and a multi-cell Zero-Forcing BeamForming (ZFBF) technique. The macro diversity technique transmits traffic data from multiple cells to only one UE. The macro diversity technique has poor frequency efficiency. However, because the macro diversity technique uses an interference channel as an effective signal channel, it can reduce the interference and increase the signal strength. The multi-cell ZFBF technique transmits traffic data from multiple cells to multiple UEs simultaneously and uses downlink channel information to reduce the interference between the UEs. The multi-cell ZFBF technique is very similar to a single-cell ZFBF technique. However, due to an addition of a backhaul and a multi-cell concept, the multi-cell ZFBF technique is difficult to implement and its throughput may depend on the backhaul characteristics.

[0006] The following document discloses an interference mitigation scheme using advanced antenna technologies based on precoding matrix indexes coordination among adjacent base stations: SHKUMBIN HAMITI, IEEE 802.16M-08/003R7, "IEEE 802.16m System Description Document [Draft]", IEEE 802.16 BROADBAND WIRELESS ACCESS WORKING GROUP, USA, 7 February 2009, pages 1-171.

[0007] As described above, the CoMP technique increases the system complexity and cannot secure performance improvement in an actual system. More specifically, the CoMP technique has the following three problems.

[0008] Firstly, the CoMP technique is problematic in terms of system operation. A conventional CoMP technique requires a fast operation in comparison with the conventional single-cell MIMO technique. For example, the CoMP technique must select target UEs and manage the selected UEs in a separate manner, which increases the complexity of a scheduler and reduces resource utilization efficiency. Also, except for the macro diversity technique, the CoMP is applicable only to a closed-loop MIMO technique. Therefore, a moving UE cannot benefit from noise reduction.

[0009] Secondly, if the conventional CoMP technique is applied to the system, cells participating in a coordination must be grouped into clusters for scheduling and transmission. In this case, because the number of cells included in a cluster is restricted, only a portion of a multi-cell interference can be controlled. Thus, although the conventional CoMP technique is applied, the throughput may be restricted by the interferences between uncontrolled remaining cells, which are received from outside of the cell cluster. Also, there is an increased probability that scheduling complexity may increase due to a cluster-by-cluster multi-cell scheduling.

[0010] Thirdly, the CoMP technique has a throughput restriction problem due to a backhaul. The conventional CoMP technique must exchange coordination information through backhaul for inter-BS coordination. In this case, the coordination level can increase according to the amount of exchanged coordination information, but the throughput may degrade due to the time delay taken for an inter-BS information exchange. Similarly, the conventional CoMP technique requires a high backhaul overhead and is very sensitive to backhaul latency. Therefore, improvement of the throughput versus the overhead may be small if there is not a good backhaul.

[0011] Therefore, a need exists for an apparatus and method for reducing an inter-cell interference while having low scheduling complexity and low backhaul dependence.

SUMMARY OF THE INVENTION



[0012] The invention is defined and limited by the scope of appended claims 1-16. In the following description, any embodiment(s) referred to and not falling within the scope of the appended claims, is (are) merely example(s) useful to the understanding of the invention.

[0013] An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide an apparatus and method for reducing an inter-cell interference in a Multi-cell Multiple Input Multiple Output (MIMO) system.

[0014] Another aspect of the present invention is to provide an apparatus and method for efficiently reducing an inter-cell interference in a MIMO system while having low scheduling complexity and low backhaul dependence.

[0015] Still another aspect of the present invention is to provide an apparatus and method for operating a codebook to reduce an inter-cell interference in a MIMO system.

[0016] A further aspect of the present invention is to provide an apparatus and method for exchanging a Codebook Subset Pattern (CSP) between cells and broadcasting the inter-cell CSP in a MIMO system.

[0017] Another aspect of the present invention is to provide an apparatus and method for each cell to adaptively update a CSP in a MIMO system.

[0018] Still another aspect of the present invention is to provide an apparatus and method for each cell to transmit a CSP update request to an adjacent cell and receive an ACKnowledge (ACK)/Non-ACKnowledge (NACK) message for the CSP update request from the adjacent cell in a MIMO system.

[0019] In accordance with an aspect of the present invention, a method for operating a CSP of a Base Station (BS) in a MIMO system is provided. The method includes determining whether there is a CSP-updated BS among the BS and adjacent BSs, exchanging the updated CSP between cells if it is determined that there is a CSP-updated BS, and broadcasting the CSP of each cell acquired through the exchange.

[0020] In accordance with another aspect of the present invention, an apparatus for operating a CSP of a BS in a MIMO system is provided. The apparatus includes a CSP updater for determining whether there is a CSP-updated BS among the BS and adjacent BSs, an inter-cell information exchanger for exchanging the updated CSP between cells if it is determined that there is a CSP-updated BS, and a signal transmitter for broadcasting the CSP of each cell acquired through the exchange.

[0021] In accordance with still another aspect of the present invention, a method for reporting a Channel Quality Indicator (CQI) of a User Equipment (UE) in a MIMO system is provided. The method includes receiving a CSP of each of a plurality of cells, receiving a Common Reference Signal (CRS) from each cell, determining a multi-cell CQI based on the received CSP and CRS of each cell, and reporting the determined multi-cell CQI to a BS.

[0022] In accordance with a further aspect of the present invention, an apparatus for reporting a CQI of a UE in a MIMO system is provided. The apparatus includes a signal receiver for receiving a CSP of each of a plurality of cells and for receiving a CRS from each cell, and a feedback information generator for determining a multi-cell CQI based on the received CSP and CRS of each cell and for reporting the determined multi-cell CQI to a BS.

[0023] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS



[0024] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a diagram illustrating an example of a Codebook Subset Pattern (CSP) according to an exemplary embodiment of the present invention;

FIG. 2 is a diagram illustrating an example of a codebook subset table according to an exemplary embodiment of the present invention;

FIG. 3 is a diagram illustrating an example where each of a plurality of cells uses one CSP according to an exemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method for a serving Base Station (BS) to transmit a CSP update request to a BS of an adjacent cell (i.e., an adjacent BS or an adjacent sector) and receive information regarding the updated CSP from the adjacent BS according to an exemplary embodiment of the present invention;

FIG. 5 is a flowchart illustrating a method for a BS of an adjacent cell (i.e., an adjacent BS or an adjacent sector) to update a CSP in response to a CSP update request of a serving BS and transmit information regarding the updated CSP to the serving BS in a MIMO system, according to an exemplary embodiment of the present invention;

FIG. 6 is a diagram illustrating an example where each of a plurality of cells use a CSP to schedule a User Equipment (UE) according to an exemplary embodiment of the present invention;

FIG. 7 is a flowchart illustrating a data transmitting method of a serving BS in a MIMO system according to an exemplary embodiment of the present invention;

FIG. 8 is a flowchart illustrating a data receiving method of a UE in a MIMO system according to an exemplary embodiment of the present invention; and

FIG. 9 is a diagram illustrating a cell structure in a MIMO system according to an exemplary embodiment of the present invention.



[0025] Throughout the drawings, like reference numerals will be understood to refer to like parts, components, and structures.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS



[0026] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the appended claims. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0027] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended.

[0028] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.

[0029] By the term "substantially" it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide

[0030] Exemplary embodiments of the present invention provide an apparatus and method for operating a codebook to reduce an inter-cell interference in a Multiple Input Multiple Output (MIMO) system.

[0031] A conventional system uses one codebook defined according to the number of antennas regardless of cells and resources. In an exemplary implementation, different codebooks according to cells and resources (time/frequency) are used. Accordingly, a codebook structure for each of predefined time/frequency resources will be referred to as a Codebook Subset Pattern (CSP). Each cell uses one CSP and transmits DownLink (DL) data through a codebook for each time/frequency resource. Herein, the codebook may be an empty set or a set of one or more precoding vectors and the precoding vector may be a vector representing a data precoding rule. Herein, the codebook being an empty set denotes that the corresponding time/frequency resource is not used for data transmission, which may be used to reliably prevent an interference with an adjacent cell.

[0032] FIG. 1 is a diagram illustrating an example of a CSP according to an exemplary embodiment of the present invention.

[0033] Referring to FIG. 1, a horizontal axis of a CSP represents a time (i.e., a subframe) and a vertical axis represents a frequency (i.e., a Resource Block (RB) or a subband). The CSP represents a color or pattern corresponding to a codebook to be used for each time/frequency resource. In an exemplary implementation, the pattern is used to represent a codebook to be used for each resource in the CSP. Herein, the representation of one or more precoding vectors constituting a codebook corresponding to each color or pattern will be referred to as a codebook subset table.

[0034] FIG. 2 is a diagram illustrating an example of a codebook subset table according to an exemplary embodiment of the present invention.

[0035] Referring to FIG. 2, the codebook subset table represents one or more precoding vectors constituting a codebook corresponding to each pattern (or color).

[0036] The codebook subset table includes supersets and subsets. Herein, the superset is a precoding vector set of a codebook including all possible precoding vectors in one codebook. The subset is a precoding vector set of a codebook including some of the possible precoding vectors in one codebook. In FIG. 2, vn denotes the nth element of a superset codebook, i.e., the nth precoding vector.

[0037] For example, if all possible precoding vectors in one codebook are v1, v2, v3 and v4, a precoding vector set {v1, v2, v3, v4} corresponds to a pattern (or color) corresponding to the superset in the codebook subset table. For example, restricted precoding vector sets {v1, v2}, {v3, v4} and {v2, v3, v4} may correspond to a pattern (or color) corresponding to the subset. Herein, the precoding vector set being {v1, v2} denotes that only the v1 and v2 among the v1, v2, v3 and v4 are used to precode data to be transmitted to a User Equipment (UE), which guarantees that an interference due to {v3, v4} will not be transmitted to an adjacent cell.

[0038] Although FIG. 2 illustrates that the codebook subset table includes one superset and a plurality of subsets, the present invention is not limited thereto. For example, the codebook subset table may further include an empty subset with an empty precoding vector set.

[0039] FIG. 3 is a diagram illustrating an example where each of a plurality of cells uses one CSP according to an exemplary embodiment of the present invention.

[0040] Referring to FIG. 3, each cell has one CSP and a codebook used for each resource in the cell is represented by a pattern (or color) in the CSP. If one CSP includes more patterns (or colors) corresponding to a superset and fewer patterns (or colors) corresponding to a subset, that is, if the cell has more resources using a superset codebook and fewer resources using a subset codebook, it is advantageous to the throughput of the cell due to a high scheduling gain in a spatial domain but increases the probability that the UEs of an adjacent cell (more particularly, the edge UEs of an adjacent cell) may receive a strong interference. Thus, in order to effectively manage an intra-cell UE distribution change and a service type for a UE, it is necessary to control a ratio of patterns (or colors) corresponding to a subset to patterns (or colors) corresponding to a superset in the CSP of each cell. Accordingly, a serving BS of the UE transmits a CSP update request to a BS of an adjacent cell (i.e., an adjacent BS), and the adjacent BS updates a CSP in response to the CSP update request and transmits information regarding the updated CSP to the serving BS.

[0041] Herein, a CSP of each cell may be randomly selected or updated, or may be adaptively selected or updated using feedback information from a UE (e.g., a Channel Quality Indicator (CQI) and an ACKnowledge (ACK)/ Non-ACKnowledge (NACK) ratio) or a downlink throughput Cumulative Density Function (CDF). Also, the CSP update may be requested by transmitting the cell loading conditions between adjacent cells or a CSP exchange request message through a backhaul. The CSP may be determined by the upper network or BSs. Hereinafter, a description will be given of a method for updating a CSP by using a downlink throughput CDF according to an exemplary embodiment of the present invention.

[0042] FIGs. 4 and 5 illustrate a method for updating a CSP and exchanging information regarding the updated CSP between cells in order to effectively manage an intra-cell UE distribution change and a service type for a UE.

[0043] FIG. 4 is a flowchart illustrating a method for a serving BS to transmit a CSP update request to a BS of an adjacent cell (i.e., an adjacent BS or an adjacent sector) and receive information regarding the updated CSP from the adjacent BS in order to reduce an inter-cell interference in a MIMO system, according to an exemplary embodiment of the present invention.

[0044] Referring to FIG. 4, in step 401, a serving BS uses a downlink throughput CDF to determine a ratio of a cell average throughput to the cell edge throughput. Herein, the throughput may be defined by a data rate (bps/Hz). For example, in the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) or the Institute of Electrical and Electronics Engineers (IEEE) standard 802.16m system, the cell edge throughput may be defined by a 5% point of the CDF.

[0045] In step 403, the serving BS determines whether the determined ratio is greater than a first threshold value.

[0046] If it is determined that the ratio is greater than the first threshold value, the serving BS determines that the cell edge throughput is lower than an allowable value due to an inter-cell interference influence and proceeds to step 405. In step 405, the serving BS generates a CSP update request message for requesting an adjacent cell to increase the amount of subset codebook resources in order to reduce an inter-cell interference received from the adjacent cell.

[0047] On the other hand, if it is determined that the ratio is not greater than the first threshold value, the serving BS proceeds to step 407. In step 407, the serving BS determines whether the determined ratio is smaller than a second threshold value. Herein, the second threshold value is set to be smaller than the first threshold value, and the first threshold value and the second threshold value are determined according to an intra-call UE distribution and a service type of a UE.

[0048] If it is determined that the ratio is smaller than the second threshold value, the serving BS determines that the cell edge throughput is higher than the allowable value due to little influence of an inter-cell interference and proceeds to step 409. In step 409, the serving BS generates a CSP update request message for requesting an adjacent cell to increase an amount of superset codebook resources.

[0049] On the other hand, if it is determined that the ratio is not smaller than the second threshold value, the serving BS determines that a CSP update is unnecessary and ends the algorithm.

[0050] In step 411, the serving BS selects one of a plurality of adjacent cells, to which the generated CSP update request message is to be transmitted. In step 413, the serving BS transmits the generated CSP update request message to a BS of the selected adjacent cell (i.e., an adjacent BS).

[0051] In step 415, the serving BS determines whether a CSP update ACK message is received from the adjacent BS. If it is determined that the CSP update ACK message is received from the adjacent BS, the serving BS proceeds to step 417. In step 417, the serving BS receives an updated CSP from the adjacent BS. Herein, the updated CSP is received through a backhaul and a cell identifier is received together with the updated CSP. Also, information regarding the application time of the updated CSP and the number of antennas of the adjacent BS may be received together with the updated CSP. Herein, in the case of LTE, the application time of the updated CSP may be represented using a System Frame Number (SFN). On the other hand, if a CSP update NACK message is received from the adjacent BS, or if the CSP update ACK message or the CSP update NACK message is not received from the adjacent BS within a preset time, the serving BS returns to step 411. In step 411, the serving BS selects one of the adjacent cells other than the adjacent cell that transmitted a CSP update NACK message.

[0052] Thereafter, the serving BS ends the algorithm.

[0053] FIG. 5 is a flowchart illustrating a method for a BS of an adjacent cell (i.e., an adjacent BS or an adjacent sector) to update a CSP in response to a CSP update request of a serving BS and transmit information regarding the updated CSP to the serving BS in a MIMO system, according to an exemplary embodiment of the present invention.

[0054] Referring to FIG. 5, in step 501, an adjacent BS determines whether a CSP update request message is received from a serving BS of a UE. Herein, the CSP update request message requests the adjacent BS to increase the amount of subset codebook resources or the amount of superset codebook resources.

[0055] If the CSP update request message is received from the serving BS, the adjacent BS proceeds to step 503. In step 503, the adjacent BS determines whether the received CSP update request message is a message for requesting the adjacent BS to increase the amount of subset codebook resources.

[0056] If it is determined that the received CSP update request message is a message for requesting the adjacent BS to increase the amount of subset codebook resources, the adjacent BS proceeds to step 505. In step 505, the adjacent BS determines whether the cell average throughput is higher than a third threshold value.

[0057] If the adjacent BS determines that the cell average throughput is higher than the third threshold value, the adjacent BS determines that there will be no serious performance problem even in the event of decreasing the amount of superset codebook resources in the current CSP and proceeds to step 507. In step 507, the adjacent BS determines whether the amount of subset codebook resources can be increased. Herein, whether the amount of subset codebook resources can be increased may be determined according to whether there is at least one superset codebook resource in the current CSP that can be changed to use a subset codebook. In an exemplary implementation, whether the amount of subset codebook resources can be increased may be determined according to whether there is a CSP that has a higher subset codebook ratio than the current CSP among the CSPs designated in the system.

[0058] If it is determined that the amount of subset codebook resources can be increased, the adjacent BS proceeds to step 509. In step 509, the adjacent BS increases the amount of subset codebook resources in a CSP to update the CSP. That is, in an exemplary implementation, a change is made to use a subset codebook for the superset codebook resources in the current CSP within a possible range. In another exemplary implementation, a change is made to use a CSP that has a higher subset codebook ratio than the current CSP among the CSPs designated in the system.

[0059] In step 511, the adjacent BS transmits a CSP update ACK message to the serving BS. In step 513, the adjacent BS transmits the updated CSP to the serving BS. Herein, the updated CSP is transmitted through a backhaul and a cell identifier is transmitted together with the updated CSP. Also, information regarding an application time of the updated CSP and a number of antennas of the adjacent BS may be transmitted together with the updated CSP. Herein, in the case of LTE, the application time of the updated CSP may be represented using an SFN. On the other hand, if the cell average throughput is not higher than the third threshold value or if the amount of subset codebook resources cannot be increased, the adjacent BS proceeds to step 519. In step 519, the adjacent BS transmits a CSP update NACK message to the serving BS. Thereafter, the adjacent BS ends the algorithm.

[0060] On the other hand, if the received CSP update request message is a message for requesting the adjacent BS to increase the amount of superset codebook resources, the adjacent BS proceeds to step 515. In step 515, the adjacent BS determines whether the amount of superset codebook resources can be increased. Herein, in an exemplary implementation, whether the amount of superset codebook resources can be increased may be determined according to whether there is at least one subset codebook resource in the current CSP that can be changed to use a superset codebook. In another exemplary implementation, whether the amount of superset codebook resources can be increased may be determined according to whether there is a CSP that has a higher superset codebook resource ratio than the current CSP among the CSPs designated in the system.

[0061] If it is determined that the amount of superset codebook resources can be increased, the adjacent BS proceeds to step 517. In step 517, the adjacent BS increases the amount of superset codebook resources in a CSP to update the CSP. That is, in an exemplary implementation, a change is made to use a superset codebook for the subset codebook resources in the current CSP within a possible range. In another exemplary implementation, a change is made to use a CSP that has a higher superset codebook resource ratio than the current CSP among the CSPs designated in the system. Thereafter, the adjacent BS returns to step 511.

[0062] On the other hand, if the amount of superset codebook resources cannot be increased, the adjacent BS proceeds to step 519. In step 519, the adjacent BS transmits a CSP update NACK message to the serving BS. Thereafter, the adjacent BS ends the algorithm.

[0063] As described above, exemplary embodiments of the present invention update a CSP of each cell and exchange the updated CSP between cells. The CSP exchanged between cells is broadcast to the UEs of the corresponding cell. An intra-cell UE determines a multi-cell CQI through a CSP for each cell based on an inter-cell interference and transmits the determined multi-cell CQI to the serving BS. Upon receiving the determined multi-cell CQI, the serving BS performs a scheduling operation based on the received multi-cell CQI. The multi-cell CQI is determined based on an inter-cell interference that is estimated through not only a codebook and a channel matrix received from the serving BS but also a codebook and a channel matrix received from adjacent BSs.

[0064] FIG. 6 is a diagram illustrating an example where each of a plurality of cells uses a CSP to schedule a UE according to an exemplary embodiment of the present invention.

[0065] Referring to FIG. 6, if a different codebook is used for each cell with respect to given time/frequency resources according to an exemplary embodiment of the present invention, UEs with high estimated SNR and inter-cell interference (such as, UE1 601, UE2 602, UE4 604, UE8 608, UE11 611 and UE13 613 have a better multi-cell CQI. Thus, it is advantageous to allocate resources through scheduling from the corresponding BSs 620 and 630.

[0066] FIG. 7 is a flowchart illustrating a data transmitting method of a serving BS in a MIMO system according to an exemplary embodiment of the present invention.

[0067] Referring to FIG. 7, in step 701, a serving BS determines whether there is a CSP-updated BS among the serving BS and adjacent BSs. If it is determined that there is no CSP-updated BS among the serving BS and adjacent BSs, the serving BS proceeds directly to step 707.

[0068] On the other hand, if it is determined that there is a CSP-updated BS among the serving BS and adjacent BSs, the serving BS proceeds to step 703. In step 703, the serving BS exchanges the updated CSP with an adjacent cell. Herein, the updated CSP is exchanged through a backhaul and a cell identifier is exchanged together with the updated CSP. Also, information regarding an application time of the updated CSP and a number of antennas of the adjacent BS may be exchanged together with the updated CSP. Herein, in the case of LTE, the application time of the updated CSP may be represented using an SFN. Accordingly, a BS of each cell acquires its own CSP, and an adjacent cell identifier and a CSP of adjacent cells.

[0069] In step 705, the serving BS broadcasts the adjacent cell identifier and the CSP for each cell, which are acquired through the exchange, to intra-cell UEs. The inter-cell CSP exchange and the broadcast to the UEs must be performed whenever the CSP is updated. Herein, application time of a new CSP is notified by an SFN, and the CSP is sufficiently exchanged before the application time based on a backhaul latency (e.g., up to 20 msec for X2) and the time taken for broadcast to a UE. Also, in order to reduce the amount of information necessary to represent the CSP, only an index may be exchanged by setting a main CSP.

[0070] In step 707, the serving BS transmits a Common Reference Signal (CRS) for channel estimation and a CQI measurement to intra-cell UEs. The following description illustrates a CRS for 3GPP. However, in the case of the IEEE standard 802.16m, a common pilot signal, such as a preamble/midamble may be transmitted to the UE.

[0071] In step 709, the serving BS determines whether a multi-cell CQI is received from an intra-cell UE. Herein, each intra-cell UE determines a multi-cell CQI based on an inter-cell interference by using the adjacent cell identifier and the CSP for each cell received from the serving BS and the CRS received from the serving cell and the adjacent cell. Also, each intra-cell transmits the determined multi-cell CQI to the serving BS.

[0072] In step 711, upon receiving the multi-cell CQI from the intra-cell UE, the serving BS uses the received multi-cell CQI to allocate each resource a UE, to which data will be transmitted, and select Transmission (TX) parameters and a TX mode of the corresponding UE. Herein, some of the resources may not be allocated a UE to which data will be transmitted. For example, the TX mode may be one of a Single User MIMO (SU-MIMO) mode such as Spatial Division Multiplexing (SDM) and a Multi User MIMO (MU-MIMO) mode such as Spatial Division Multiple Access (SDMA). Herein, the TX parameters may include a TX stream, a subchannel, a precoding vector, a rank, a Modulation and Coding Selection (MCS) level and the like.

[0073] In step 713, the serving BS uses the selected TX mode and TX parameters to transmit data. Thereafter, the serving BS ends the algorithm.

[0074] FIG. 8 is a flowchart illustrating a data receiving method of a UE in a MIMO system according to an exemplary embodiment of the present invention.

[0075] Referring to FIG. 8, in step 801, a UE determines whether the reception of an updated CSP is necessary. If it is determined that the reception of an updated CSP is not necessary, the UE proceeds directly to step 805. On the other hand, if it is determined that the reception of an updated CSP is necessary, the UE proceeds to step 803. In step 803, the UE receives an adjacent cell identifier and a CSP for each cell from a serving BS.

[0076] In step 805, the UE determines whether a CRS is received from the serving cell and the adjacent cell. If it is determined that a CRS is received from the serving cell and the adjacent cell, the UE proceeds to step 807. In step 807, the UE determines a multi-cell CQI based on an inter-cell interference by using the adjacent cell identifier and the CSP for each cell received from the serving BS and the CRS received from the serving cell and the adjacent cell.

[0077] Herein, the multi-cell CQI is determined as follows. A BS of each cell multiplies a CRS signal, which is used to estimate a channel undergone by a TX signal of the corresponding cell, by a scrambling sequence allocated to each cell and transmits the scrambled CRS signal to a UE. Herein, the UE may use the cell identifiers of the adjacent cells and the serving cell to extract the scrambling sequence allocated to each cell. Also, the UE extracts a signal of the CRS-allocated resource from a Reception (RX) signal, descrambles the extracted signal by the allocated scrambling sequence to acquire a CRS signal of each cell, and uses the acquired CRS signal to determine a channel estimation value of each cell. Also, the UE uses the CSP of the adjacent cell and the serving cell to search a codebook of the adjacent cells and the serving cell corresponding to each time/frequency resource, and uses the channel estimation value of each cell to measure elements of the codebook searched for each cell, i.e., the multi-cell CQI corresponding to each precoding vector.

[0078] In step 809, the UE transmits the determined multi-cell CQI to the serving BS. In step 811, the UE receives data from the serving BS according to the scheduling performed by the serving BS based on the multi-cell CQI received from intra-cell UEs.

[0079] Thereafter, the UE ends the algorithm.

[0080] As described above, in an exemplary embodiment of the present invention, the UE determines a multi-cell CQI through a CSP update and inter-cell CSP exchange to perform a scheduling operation, thus giving an inter-cell interference reduction effect to all the UEs in the cell. Herein, it should be noted that the multi-cell CQIs of adjacent cells become different if some cell does not use a codebook designated in a CSP. Accordingly, the following scheduling restrictions are required. Because transmission schemes using a codebook based on 3GPP, such as open-loop Spatial Multiplexing (SM), closed-loop SM, multi-user MIMO and closed-loop rank=1 precoding, use a codebook designated in a CSP, the transmission schemes may be used in any time/frequency resource. However, because transmission schemes not using a codebook, such as a single-antenna port (port 0), transmit diversity and a single-antennal port (port 5), do not use a codebook designated in a CSP, the transmission schemes may be used in a time/frequency resource allocated a superset codebook in a CSP.

[0081] FIG. 9 is a diagram illustrating a cell structure in a MIMO system according to an exemplary embodiment of the present invention.

[0082] Referring to FIG. 9, a BS 900 includes a CSP updater 902, an inter-cell information exchanger 903, a feedback information processor 904, a selector 906, and a signal transmitter 908. Each of a plurality of UEs 910-1 ∼ 910-N in a cell includes a signal receiver 912, a channel estimator 914, and a feedback information generator 916.

[0083] Regarding the BS 900, the CSP updater 902 determines the ratio of the cell average throughput to the cell edge throughput, compares the determined ratio with a preset threshold value to generate a CSP update request message for requesting the update of the amount of subset codebook resources and the amount of superset codebook resources, and transmits the generated CSP update request message through the inter-cell information exchanger 903 to an adjacent cell. Herein, the CSP updater 902 may receive a CSP update ACK message or a CSP update NACK message, which indicates the possibility of a CSP update, from the adjacent cell through the inter-cell information exchanger 903. Thereafter, when the adjacent cell updates its own CSP according to the request, the CSP updater 902 exchanges the updated CSP with the adjacent cell through the inter-cell information exchanger 903 and broadcasts the same through the signal transmitter 908 together with an adjacent cell identifier. Meanwhile, if a CSP update request message is received from the adjacent cell through the inter-cell information exchanger 903, the CSP updater 902 determines the possibility of the CSP update, transmits a CSP update ACK message or a CSP update NACK message, which indicates the possibility of CSP update, through the inter-cell information exchanger 903 to the adjacent cell, updates a CSP within a possible range, and transmits the updated CSP through the inter-cell information exchanger 903 to the adjacent cell. Herein, the CSP updater 902 may transmit its own cell identifier together with the updated CSP. Also, information regarding the application time of the updated CSP and the number of its own antennas may be transmitted together with the updated CSP. Herein, in the case of LTE, an application time of the updated CSP may be represented using an SFN.

[0084] For exchange of inter-cell information or messages with the BS 900, the inter-cell information exchanger 903 transmits a signal from the CSP updater 902 through an antenna to the adjacent cell and provides the CSP updater 902 with a signal received from the adjacent cell through an antenna.

[0085] The feedback information processor 904 receives a multi-cell CQI as feedback information from the UEs 910-1 ∼ 910-N and outputs the received multi-cell CQI to the selector 906.

[0086] The selector 906 uses the multi-cell CQI from the UEs 910-1 ∼ 910-N to allocate each resource a UE, to which data will be transmitted, and select TX parameters and a TX mode of the corresponding UE. The selector 906 outputs the selected TX mode and TX parameters to the signal transmitter 908. For example, the TX mode may be one of a Single User MIMO (SU-MIMO) mode such as Spatial Division Multiplexing (SDM) and a Multi User MIMO (MU-MIMO) mode such as Spatial Division Multiple Access (SDMA). Herein, the TX parameters may include a TX stream, a subchannel, a precoding vector, a rank, an MCS level and the like.

[0087] The signal transmitter 908 uses the selected TX mode and TX parameters to transmit data through an antenna. Also, the signal transmitter 908 transmits a CRS at each subframe.

[0088] Regarding each of the UEs 910-1 ∼ 910-N, the signal receiver 912 receives a signal through one or more antennas and outputs the Received (RX) signal.

[0089] The channel estimator 914 receives a cell identifier of adjacent cells, which is transmitted by a serving BS through the signal receiver 912 and uses the cell identifier of the adjacent cells and the serving cell to extract a scrambling sequence allocated to each cell. Also, the channel estimator 914 receives a signal, which is transmitted by the serving cell and the adjacent cells, through the signal receiver 912, extracts a signal of the CRS-allocated resource from the RX signal, and descrambles the extracted signal by the allocated scrambling sequence to acquire a CRS signal of each cell. Thereafter, the channel estimator 914 uses the acquired CRS signal to determine a channel estimation value of each cell and outputs the determined channel estimation value to the feedback information generator 916.

[0090] The feedback information generator 916 receives a CSP of the adjacent cell and the serving cell from the serving BS through the signal receiver 912, uses the CSP of the adjacent cell and the serving cell to search a codebook of the adjacent cells and the serving cell corresponding to each time/frequency resource, and uses the channel estimation value of each cell to measure elements of the codebook searched for each cell, i.e., the multi-cell CQI corresponding to each precoding vector. Thereafter, the feedback information generator 916 generates the measured multi-cell CQI as feedback information and feeds back the same to the serving BS.

[0091] As described above, exemplary embodiments of the present invention adaptively update a CSP of each cell in a multi-cell MIMO system, exchange the updated CSP between cells and broadcast the exchanged inter-cell CSP, thereby effectively reducing the inter-cell interference of all the UEs in the cell by exchanging a small amount of information between the cells. Also, exemplary embodiments of the present invention, which include conventional scheduling complexity without using the inter-cell interference technique, have a very low scheduling complexity in comparison with other CoMP techniques. The reason for this is that a scheduling operation for each cell is performed independently, discrimination between a cell center UE and a cell edge UE is not necessary and discrimination between a low-mobility UE and a high-mobility UE is not necessary to apply the inter-cell interference reduction technology. Accordingly, the CSP is exchanged only when the CSP is updated. Thus, backhaul overhead is very low and is robust against backhaul latency, and the number of cells participating in BS coordination has no limit.


Claims

1. A method for operating a serving Base Station, BS, (900) in a Multiple Input Multiple Output, MIMO, system comprising the serving BS and at least one adjacent BS, wherein each of the serving BS and the at least one adjacent BS is associated with one or more cells, and wherein each cell uses a Codebook Subset Pattern, CSP, to schedule a User Equipment, UE, (910) the method comprising:

determining (701) whether there is a BS having an updated CSP among the serving BS and the at least one adjacent BS;

if it is determined that there is a BS having the updated CSP among the serving BS and the at least one adjacent BS, acquiring CSPs of the serving BS and the at least one adjacent BS by exchanging (703) the updated CSP with the at least one adjacent BS;

broadcasting (705) the acquired CSPs to at least one intra-cell UE of the serving BS;

transmitting (707) a Common Reference Signal, CRS, to the at least one intra-cell UE;

receiving (709) a multi-cell Channel Quality Indicator, CQI, from the at least one intra-cell UE; and

performing (711) a scheduling operation based on the received multi-cell CQI,

wherein the CSP represents a pattern corresponding to a codebook for each predefined time/frequency resource, and wherein the codebook comprises an empty set or a set of one or more precoding vectors,

wherein the method further comprises:

determining (401) a ratio of a cell average throughput to a cell boundary throughput;

comparing (403) the determined ratio with a threshold value to generate (405, 409) a CSP update request message for requesting the at least one adjacent BS to perform a CSP update;

transmitting (413) the generated CSP update request message to the at least one adjacent BS; and

receiving (417) the updated CSP from the at least one adjacent BS, and

wherein the generating (405, 409) of the CSP update request message comprises:

generating (405) a CSP update request message for requesting the at least one adjacent BS to increase an amount of subset codebook resources when it is determined that the ratio is greater than a first threshold value;

generating (409) a CSP update request message for requesting the at least one adjacent BS to increase an amount of superset codebook resources when it is determined that the ratio is not greater than the first threshold value and is smaller than a second threshold value; and

not generating a CSP update request message when it is determined that the ratio is not greater than the first threshold value and is not smaller than a second threshold value,

wherein the first threshold value and the second threshold value vary according to an intra-cell UE distribution and a service type of a UE,

wherein the second threshold value is set to be smaller than the first threshold value, and

wherein a superset codebook comprises a precoding vector set including all possible precoding vectors in one codebook.


 
2. The method of claim 1, further comprising:
receiving a CSP update ACKnowledge, ACK/Non-ACKnowledge, NACK, message for the request from the at least one adjacent BS before receiving the updated CSP from the at least one adjacent BS.
 
3. The method of claim 1, wherein at least one of the application time of the updated CSP and the number of antennas of the at least one adjacent BS is received from the at least one adjacent BS together with the updated CSP.
 
4. The method of claim 1, further comprising:

updating a CSP when receiving a CSP update request message from the at least one adjacent BS; and

transmitting the updated CSP to the at least one adjacent BS.


 
5. The method of claim 4, wherein the updating of the CSP comprises:

upon receiving a CSP update request message for requesting an increase in an amount of subset codebook resources from the adjacent cell, determining whether the cell average throughput is greater than a threshold value and updating the CSP by increasing the amount of subset codebook resources in the CSP when the cell average throughput is greater than the threshold value; and

upon receiving a CSP update request message for requesting an increase in an amount of superset codebook resources from the adjacent cell, updating the CSP by increasing the amount of superset codebook resources in the CSP,

wherein a superset codebook comprises a precoding vector set including all possible precoding vectors in one codebook.


 
6. The method of claim 4, further comprising:
transmitting a CSP update ACKnowledge, ACK/Non-ACKnowledge, NACK, message to the at least one adjacent BS before transmitting the updated CSP to the at least one adjacent BS.
 
7. The method of claim 4, wherein at least one of the application time of the updated CSP and the number of antennas of the adjacent cell is transmitted to the serving cell together with the updated CSP.
 
8. The method of claim 1, wherein the performing a scheduling operation based on the received multi-cell CQI comprising:

using the received multi-cell CQI to allocate each resource to an intra-cell UE, which is to receive data, and to select a Transmission, TX, parameter and a TX mode of the intra-cell UE; and

transmitting data by using the selected TX mode and TX parameter.


 
9. An apparatus for operating a serving Base Station, BS, (900) in a Multiple Input Multiple Output, MIMO, system comprising the serving BS and at least one adjacent BS, wherein each of the serving BS and the at least one adjacent BS is associated with one or more cells, and wherein each cell uses a Codebook Subset Pattern, CSP, to schedule a User Equipment, UE, (910) the apparatus comprising:

a CSP updater (902) for determining whether there is a BS having an updated CSP among the serving BS and the at least one adjacent BS;

an inter-cell information exchanger (903) for acquiring CSPs of the serving BS and the at least one adjacent BS by exchanging the updated CSP with the at least one adjacent BS, if it is determined that there is a BS having the updated CSP among the serving BS and the at least one adjacent BS;

a signal transmitter (908) for broadcasting the acquired CSP to at least one intra-cell UE of the serving BS, and transmitting a Common Reference Signal, CRS, to the at least one intra-cell UE;

a feedback information processor (904) for receiving a multi-cell Channel Quality Indicator, CQI from the at least one intra-cell UE; and

a selector (906) for performing a scheduling operation based on the received multi-cell CQI,

wherein the CSP represents a pattern corresponding to a codebook for each predefined time/frequency resource, and wherein the codebook comprises an empty set or a set of one or more precoding vectors,

wherein the CSP updater (902) is configured for:

determining a ratio of a cell average throughput to a cell boundary throughput;

comparing the determined ratio with a threshold value to generate a CSP update request message for requesting the at least one adjacent BS to perform a CSP update;

transmitting the generated CSP update request message to the at least one adjacent BS through the inter-cell information exchanger; and

receiving the updated CSP from the at least one adjacent BS through the inter-cell information exchanger (903), and

wherein the CSP updater (902) is further configured for generating the CSP update request message by:

generating a CSP update request message for requesting the at least one adjacent BS to increase an amount of subset codebook resources when it is determined that the ratio is greater than a first threshold value;

generating a CSP update request message for requesting the at least one adjacent BS to increase an amount of superset codebook resources when it is determined that the ratio is not greater than the first threshold value and is smaller than a second threshold value; and

not generating a CSP update request message when it is determined that the ratio is not greater than the first threshold value and is not smaller than a second threshold value,

wherein the first threshold value and the second threshold value vary according to an intra-cell UE distribution and a service type of a UE,

wherein the second threshold value is set to be smaller than the first threshold value, and

wherein a superset codebook comprises a precoding vector set including all possible precoding vectors in one codebook.


 
10. The apparatus of claim 9, wherein the CSP updater is configured for:
receiving, through the inter-cell information exchanger, a CSP update ACKnowledge, ACK/Non-ACKnowledge, NACK, message for the request from the at least one adjacent BS before receiving the updated CSP from the at least one adjacent BS.
 
11. The apparatus of claim 9, wherein at least one of the application time of the updated CSP and the number of antennas of the at least one adjacent BS is received from the at least one adjacent BS together with the updated CSP.
 
12. The apparatus of claim 9, wherein the CSP updater is configured for:

updating a CSP when receiving a CSP update request message from at least one adjacent BS through the inter-cell information exchanger; and

transmitting the updated CSP to the at least one adjacent BS through the inter-cell information exchanger.


 
13. The apparatus of claim 12, wherein the CSP updater is configured for updating the CSP by:

upon receiving, through the inter-cell information exchanger, a CSP update request message for requesting an increase in an amount of subset codebook resources from the adjacent cell, determining whether the cell average throughput is greater than a threshold value and updating the CSP by increasing the amount of subset codebook resources in the CSP when the cell average throughput is greater than the threshold value; and

upon receiving, through the inter-cell information exchanger, a CSP update request message for requesting an increase in an amount of superset codebook resources from the adjacent cell, updating the CSP by increasing the amount of superset codebook resources in the CSP,

wherein a superset codebook comprises a precoding vector set including all possible precoding vectors in one codebook.


 
14. The apparatus of claim 12, wherein the CSP updater is configured for:
transmitting, through the inter-cell information exchanger, a CSP update ACKnowledge, ACK/Non-ACKnowledge, NACK, message to the at least one adjacent BS before transmitting the updated CSP to the at least one adjacent BS.
 
15. The apparatus of claim 12, wherein at least one of the application time of the updated CSP and the number of antennas of the adjacent cell is transmitted to the serving cell together with the updated CSP.
 
16. The apparatus of claim 9,
wherein the selector uses the received multi-cell CQI to allocate each resource to an intra-cell UE, which is to receive data, and to select a Transmission, TX, parameter and a TX mode of the intra-cell UE, and
wherein the signal transmitter is configured for transmitting data by using the selected TX mode and TX parameter.
 


Ansprüche

1. Verfahren zum Betreiben einer bedienenden Basisstation, BS, (900) in einem System mit mehreren Ein- und Ausgängen, MIMO, das die bedienende BS und mindestens eine benachbarte BS aufweist, wobei jede der bedienenden BS und der mindestens einen benachbarten BS einer oder mehreren Zellen zugehörig ist, und wobei jede Zelle ein Codebuch-Untergruppenmuster, CSP, zum Planen eines Benutzergeräts, UE, (910) verwendet, wobei das Verfahren aufweist:

ein Bestimmen (701), ob eine BS mit einem aktualisierten CSP unter den bedienenden BS und der mindestens einen benachbarten BS vorhanden ist;

wenn bestimmt wird, dass eine BS mit dem aktualisierten CSP unter der bedienenden BS und der mindestens einen benachbarten BS vorhanden ist, ein Erfassen von CSPs der bedienenden BS und der mindestens einen benachbarten BS durch ein Austauschen (703) des aktualisierten CSP mit der mindestens einen benachbarten BS;

ein Rundsenden (705) der erfassten CSPs an mindestens ein Intrazellen-UE der bedienenden BS; ein Übertragen (707) eines gemeinsamen Referenzsignals, CRS, an das mindestens eine Intrazellen-UE;

ein Empfangen (709) eines Mehrzellen-Kanalqualitätsindikators, CQI, von dem mindestens einen Intrazellen-UE;

und ein Ausführen (711) einer Planungsoperation auf Grundlage des empfangenen Mehrzellen-CQI, wobei das CSP ein Muster darstellt, das einem Codebuch für jede vordefinierte Zeit/Frequenz-Ressource entspricht, und wobei das Codebuch ein leeres Set oder ein Set von einem oder mehreren Vorcodierungsvektoren aufweist, wobei das Verfahren ferner aufweist:

ein Bestimmen (401) eines Verhältnisses eines Zellendurchschnitt-Durchsatzes zu einem Zellengrenzen-Durchsatz;

ein Vergleichen (403) des bestimmten Verhältnisses mit einem Schwellenwert, um eine CSP-Aktualisierungsanforderungsnachricht zu generieren (405, 409), um die mindestens eine benachbarte BS aufzufordern, eine CSP-Aktualisierung auszuführen;

ein Übertragen (413) der generierten CSP-Aktualisierungsanforderungsnachricht zu der mindestens einen benachbarten BS;

und ein Empfangen (417) des aktualisierten CSP von der mindestens einen benachbarten BS, und wobei das Generieren (405, 409) der CSP-Aktualisierungsanforderungsnachricht aufweist:

ein Generieren (405) einer CSP-Aktualisierungsanforderungsnachricht zum Auffordern der mindestens einen benachbarten BS, eine Menge von Untergruppen-Codebuchressourcen zu erhöhen, wenn bestimmt wird, dass das Verhältnis größer als ein erster Schwellenwert ist;

ein Generieren (409) einer CSP-Aktualisierungsanforderungsnachricht zum Auffordern der mindestens einen benachbarten BS, eine Menge von Obergruppen-Codebuchressourcen zu erhöhen, wenn bestimmt wird, dass das Verhältnis nicht größer als der erste Schwellenwert und kleiner als ein zweiter Schwellenwert ist;

und kein Generieren einer CSP-Aktualisierungsanforderungsnachricht , wenn bestimmt wird, dass das Verhältnis nicht größer als der erste Schwellenwert und nicht kleiner als ein zweiter Schwellenwert ist, wobei der erste Schwellenwert und der zweite Schwellenwert gemäß einer Intrazellen-UE-Verteilung und eines Diensttyps eines UE variieren, wobei der zweite Schwellenwert so eingerichtet ist, dass er kleiner als der erste Schwellenwert ist, und wobei ein Obergruppen-Codebuch ein Vorcodierungsvektorset aufweist, das alle möglichen Vorcodierungsvektoren in einem Codebuch enthält.


 
2. Verfahren nach Anspruch 1, ferner aufweisend:
ein Empfangen einer CSP-Aktualisierungsbestätigungs-, ACK/Nicht-Bestätigungs-, NACK, Nachricht auf die Anforderung von der mindestens einen benachbarten BS, bevor das aktualisierte CSP von der mindestens einen benachbarten BS empfangen wird.
 
3. Verfahren nach Anspruch 1, wobei mindestens entweder die Anwendungszeit des aktualisierten CSP oder die Anzahl von Antennen der mindestens einen benachbarten BS von der mindestens einen benachbarten BS zusammen mit dem aktualisierten CSP empfangen wird.
 
4. Verfahren nach Anspruch 1, ferner aufweisend:

ein Aktualisieren eines CSP beim Empfangen einer CSP-Aktualisierungsanforderungsnachricht von der mindestens einen benachbarten BS;

und ein Übertragen des aktualisierten CSP zu der mindestens einen benachbarten BS.


 
5. Verfahren nach Anspruch 4, wobei das Aktualisieren des CSP aufweist:

bei Empfangen einer CSP-Aktualisierungsanforderungsnachricht zum Anfordern einer Erhöhung einer Menge von Untergruppen-Codebuchressourcen von der benachbarten Zelle, ein Bestimmen, ob der Zellendurchschnitt-Durchsatz größer als ein Schwellenwert ist, und ein Aktualisieren des CSP durch Erhöhen der Menge von Untergruppen-Codebuchressourcen in dem CSP, wenn der Zellendurchschnitt-Durchsatz größer als der Schwellenwert ist;

und bei Empfangen einer CSP-Aktualisierungsanforderungsnachricht zum Anfordern einer Erhöhung einer Menge von Obergruppen-Codebuchressourcen von der benachbarten Zelle, ein Aktualisieren des CSP durch Erhöhen der Menge von Obergruppen-Codebuchressourcen in dem CSP, wobei ein Obergruppen-Codebuch ein Vorcodierungsvektorset aufweist, dass alle möglichen Vorcodierungsvektoren in einem Codebuch aufweist.


 
6. Verfahren nach Anspruch 4, ferner aufweisend:
ein Übertragen einer CSP-Aktualisierungsbestätigungs-, ACK/Nicht-Bestätigungs-, NACK, Nachricht zu der mindestens einen benachbarten BS, bevor das aktualisierte CSP zu der mindestens einen benachbarten BS übertragen wird.
 
7. Verfahren nach Anspruch 4, wobei mindestens entweder die Anwendungszeit des aktualisierten CSP oder die Anzahl von Antennen der benachbarten Zelle zusammen mit dem aktualisierten CSP zu der bedienenden Zelle übertragen wird.
 
8. Verfahren nach Anspruch 1, wobei das Ausführen einer Planungsoperation auf Grundlage des empfangenen Mehrzellen-CQI aufweist:

ein Verwenden des empfangenen Mehrzellen-CQI, um jede Ressource einem Intrazellen-UE zuzuweisen, das Daten empfangen soll, und einen Übertragungs-, TX, Parameter und einen TX-Modus des Intrazellen-UE auszuwählen;

und ein Übertragen von Daten unter Verwendung des ausgewählten TX-Modus und TX-Parameters.


 
9. Vorrichtung zum Betreiben einer bedienenden Basisstation, BS, (900) in einem System mit mehreren Ein- und Ausgängen, MIMO, das die bedienende BS und mindestens eine benachbarte BS aufweist, wobei jede der bedienenden BS und der mindestens einen benachbarten BS einer oder mehreren Zellen zugehörig ist, und wobei jede Zelle ein Codebuch-Untergruppenmuster, CSP, zum Planen eines Benutzergeräts, UE, (910) verwendet, wobei die Vorrichtung aufweist:

ein CSP-Aktualisierungsprogramm (902) zum Bestimmen, ob eine BS mit einem aktualisierten CSP unter den bedienenden BS und der mindestens einen benachbarten BS vorhanden ist;

eine Zwischenzellen-Informationsaustauschvorrichtung (903) zum Erfassen von CSPs der bedienenden BS und der mindestens einen benachbarten BS durch ein Austauschen des aktualisierten CSP mit der mindestens einen benachbarten BS, wenn bestimmt wird, dass eine BS mit dem aktualisierten CSP unter der bedienenden BS und der mindestens einen benachbarten BS vorhanden ist;

einen Signalsender (908) zum Rundsenden des erfassten CSP an mindestens ein Intrazellen-UE der bedienenden BS, und ein Übertragen eines gemeinsamen Referenzsignals, CRS, an das mindestens eine Intrazellen-UE;

einen Rückmeldeinformationen-Prozessor (904) zum Empfangen eines Mehrzellen-Kanalqualitätsindikators, CQI, von dem mindestens einen Intrazellen-UE;

und einen Selektor (906) zum Ausführen einer Planungsoperation auf Grundlage des empfangenen Mehrzellen-CQI,

wobei das CSP ein Muster darstellt, das einem Codebuch für jede vordefinierte Zeit/Frequenz-Ressource entspricht, und wobei das Codebuch ein leeres Set oder ein Set von einem oder mehreren Vorcodierungsvektoren aufweist,

wobei das CSP-Aktualisierungsprogramm (902) konfiguriert ist für:

ein Bestimmen eines Verhältnisses eines Zellendurchschnitt-Durchsatzes zu einem Zellengrenzen-Durchsatz;

ein Vergleichen des bestimmten Verhältnisses mit einem Schwellenwert, um eine CSP-Aktualisierungsanforderungsnachricht zu generieren, um die mindestens eine benachbarte BS aufzufordern, eine CSP-Aktualisierung auszuführen;

ein Übertragen der generierten CSP-Aktualisierungsanforderungsnachricht zu der mindestens einen benachbarten BS über die Zwischenzellen-Informationsaustauschvorrichtung;

und ein Empfangen des aktualisierten CSP von der mindestens einen benachbarten BS über die Zwischenzellen-Informationsaustauschvorrichtung (903), und wobei das CSP-Aktualisierungsprogramm (902) ferner konfiguriert ist, um die CSP-Aktualisierungsanforderungsnachricht zu generieren durch:

ein Generieren einer CSP-Aktualisierungsanforderungsnachricht zum Auffordern der mindestens einen benachbarten BS, eine Menge von Untergruppen-Codebuchressourcen zu erhöhen, wenn bestimmt wird, dass das Verhältnis größer als ein erster Schwellenwert ist;

ein Generieren einer CSP-Aktualisierungsanforderungsnachricht zum Auffordern der mindestens einen benachbarten BS, eine Menge von Obergruppen-Codebuchressourcen zu erhöhen, wenn bestimmt wird, dass das Verhältnis nicht größer als der erste Schwellenwert und kleiner als ein zweiter Schwellenwert ist;

und kein Generieren einer CSP-Aktualisierungsanforderungsnachricht , wenn bestimmt wird, dass das Verhältnis nicht größer als der erste Schwellenwert und nicht kleiner als ein zweiter Schwellenwert ist, wobei der erste Schwellenwert und der zweite Schwellenwert gemäß einer Intrazellen-UE-Verteilung und eines Diensttyps eines UE variieren, wobei der zweite Schwellenwert so eingerichtet ist, dass er kleiner als der erste Schwellenwert ist, und wobei ein Obergruppen-Codebuch ein Vorcodierungsvektorset aufweist, das alle möglichen Vorcodierungsvektoren in einem Codebuch enthält.


 
10. Vorrichtung nach Anspruch 9, wobei das CSP-Aktualisierungsprogramm konfiguriert ist für:
ein Empfangen, über die Zwischenzellen-Informationsaustauschvorrichtung, einer CSP-Aktualisierungsbestätigungs-, ACK/Nicht-Bestätigungs-, NACK, Nachricht auf die Anforderung von der mindestens einen benachbarten BS, bevor das aktualisierte CSP von der mindestens einen benachbarten BS empfangen wird.
 
11. Vorrichtung nach Anspruch 9, wobei mindestens entweder die Anwendungszeit des aktualisierten CSP oder die Anzahl von Antennen der mindestens einen benachbarten BS von der mindestens einen benachbarten BS zusammen mit dem aktualisierten CSP empfangen wird.
 
12. Vorrichtung nach Anspruch 9, wobei das CSP-Aktualisierungsprogramm konfiguriert ist für:

ein Aktualisieren eines CSP beim Empfangen einer CSP-Aktualisierungsanforderungsnachricht von der mindestens einen benachbarten BS über die Zwischenzellen-Informationsaustauschvorrichtung;

und ein Übertragen des aktualisierten CSP zu der mindestens einen benachbarten BS über die Zwischenzellen-Informationsaustauschvorrichtung.


 
13. Vorrichtung nach Anspruch 12, wobei das CSP-Aktualisierungsprogramm konfiguriert ist zum Aktualisieren des CSP durch:

bei Empfangen, über die Zwischenzellen-Informationsaustauschvorrichtung, einer CSP-Aktualisierungsanforderungsnachricht zum Anfordern einer Erhöhung einer Menge von Untergruppen-Codebuchressourcen von der benachbarten Zelle, ein Bestimmen, ob der Zellendurchschnitt-Durchsatz größer als ein Schwellenwert ist, und ein Aktualisieren des CSP durch Erhöhen der Menge von Untergruppen-Codebuchressourcen in dem CSP, wenn der Zellendurchschnitt-Durchsatz größer als der Schwellenwert ist;

und bei Empfangen, über die die Zwischenzellen-Informationsaustauschvorrichtung, einer CSP-Aktualisierungsanforderungsnachricht zum Anfordern einer Erhöhung einer Menge von Obergruppen-Codebuchressourcen von der benachbarten Zelle, ein Aktualisieren des CSP durch Erhöhen der Menge von Obergruppen-Codebuchressourcen in dem CSP, wobei ein Obergruppen-Codebuch ein Vorcodierungsvektorset aufweist, dass alle möglichen Vorcodierungsvektoren in einem Codebuch aufweist.


 
14. Vorrichtung nach Anspruch 12, wobei das CSP-Aktualisierungsprogramm konfiguriert ist für:
ein Übertragen, über die Zwischenzellen-Informationsaustauschvorrichtung, einer CSP-Aktualisierungsbestätigungs-, ACK/Nicht-Bestätigungs-, NACK, Nachricht zu der mindestens einen benachbarten BS, bevor das aktualisierte CSP zu der mindestens einen benachbarten BS übertragen wird.
 
15. Vorrichtung nach Anspruch 12, wobei mindestens entweder die Anwendungszeit des aktualisierten CSP oder die Anzahl von Antennen der benachbarten Zelle zusammen mit dem aktualisierten CSP zu der bedienenden Zelle übertragen wird.
 
16. Vorrichtung nach Anspruch 9, wobei der Selektor den empfangenen Mehrzellen-CQI verwendet, um jede Ressource einem Intrazellen-UE zuzuweisen, das Daten empfangen soll, und einen Übertragungs-, TX, Parameter und einen TX-Modus des Intrazellen-UE auszuwählen, und wobei der Signalsender konfiguriert ist für ein Übertragen von Daten unter Verwendung des ausgewählten TX-Modus und TX-Parameters.
 


Revendications

1. Procédé d'exploitation d'une station de base, BS, de desserte (900) dans un système à entrées multiples sorties multiples, MIMO, comprenant la BS de desserte et au moins une BS adjacente, dans lequel chacune de la BS de desserte et l'au moins une BS adjacent est associée à une ou plusieurs cellules, et dans lequel chaque cellule utilise un diagramme de sous-ensemble de répertoire, CSP, pour planifier un équipement d'utilisateur, UE, (910) le procédé comprenant :

la détermination (701) s'il existe ou s'il n'existe pas de BS ayant un CSP actualisé parmi la BS de desserte et l'au moins une BS adjacente ;

s'il est déterminé qu'il existe une BS ayant le CSP actualisé parmi la BS de desserte et l'au moins une BS adjacente, l'acquisition de CSP de la BS de desserte et l'au moins une BS adjacente en échangeant (703) le CSP actualisé avec celui de l'au moins une BS adjacente ;

la diffusion (705) des CSP acquis à au moins un UE intracellulaire de la BS de desserte ; la transmission (707) d'un signal de référence commun, CRS, à l'au moins un UE intracellulaire ;

la réception (709) d'un indicateur de qualité de canal, CQI, multicellulaires depuis l'au moins un UE intracellulaire ;

et l'exécution (711) d'une opération de planification sur la base du CQI multicellulaires reçu, dans lequel le CSP représente un diagramme correspondant à un répertoire pour chaque ressource de temps/fréquence prédéfinie, et dans lequel le répertoire comprend un ensemble vide ou un ensemble d'un ou plusieurs vecteurs précodants, dans lequel le procédé comprend en outre :

la détermination (401) d'un ratio d'un débit moyen de cellules par rapport à un débit de limite de cellules ;

la comparaison (403) du ratio déterminé à une valeur seuil pour générer (405, 409) un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'exécuter une actualisation du CSP ;

la transmission (413) du message de requête d'actualisation de CSP généré à l'au moins une BS adjacente ;

et la réception (417) du CSP actualisé depuis l'au moins une BS adjacente, et dans lequel la génération (405, 409) du message de requête d'actualisation de CSP comprend :

la génération (405) d'un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'augmenter une quantité de ressources de répertoire du sous-ensemble quand il est déterminé que le ratio est supérieur à une première valeur seuil ;

la génération (409) d'un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'augmenter une quantité de ressources de répertoire du sur-ensemble quand il est déterminé que le ratio n'est pas supérieur à une première valeur seuil et est inférieur à une deuxième valeur seuil ;

et la non-génération d'un message de requête d'actualisation de CSP quand il est déterminé que le ratio n'est pas supérieur à la première valeur seuil et n'est pas inférieur à une deuxième valeur seuil, dans lequel la première valeur seuil et la deuxième valeur seuil varient en fonction d'une répartition d'UE intracellulaire et d'un type de service d'un UE, dans lequel la deuxième valeur seuil est définie pour être inférieure à la première valeur seuil, et dans lequel un répertoire du sur-ensemble comprend un ensemble de vecteurs précodants incluant tous les vecteurs précodants possibles dans un même répertoire.


 
2. Procédé selon la revendication 1, comprenant en outre :
la réception d'un message d'accusé ACK/non-accusé, NACK, d'actualisation de CSP pour la requête depuis l'au moins une BS adjacente avant la réception du CSP actualisé depuis l'au moins une BS adjacente.
 
3. Procédé selon la revendication 1, dans lequel au moins l'un du temps d'application du CSP actualisé et du nombre d'antennes de l'au moins une BS adjacente est reçu depuis l'au moins une BS adjacente conjointement au CSP actualisé.
 
4. Procédé selon la revendication 1, comprenant en outre :

l'actualisation d'un CSP lors de la réception d'un message de requête d'actualisation de CSP depuis l'au moins une BS adjacente ;

et la transmission du CSP actualisé à l'au moins une BS adjacente.


 
5. Procédé selon la revendication 4, dans lequel l'actualisation du CSP comprend :

à la réception d'un message de requête d'actualisation de CSP pour demander une augmentation d'une quantité de ressources de répertoire du sous-ensemble depuis la cellule adjacente, la détermination si le débit moyen de cellules est supérieur à une valeur seuil et l'actualisation du CSP en augmentant la quantité de ressources du répertoire du sous-ensemble dans le CSP quand le débit moyen de cellules est supérieur à la valeur seuil ;

et à la réception d'un message de requête d'actualisation de CSP pour demander une augmentation d'une quantité de ressources de répertoire du sur-ensemble depuis la cellule adjacente, l'actualisation du CSP en augmentant la quantité de ressources du répertoire du sur-ensemble dans le CSP, dans lequel un répertoire du sur-ensemble comprend un ensemble de vecteurs précodants incluant tous les vecteurs précodants possibles dans un même répertoire.


 
6. Procédé selon la revendication 4, comprenant en outre :
la transmission d'un message d'accusé, ACK/non-accusé, NACK, d'actualisation de CSP à l'au moins une BS adjacente avant la transmission du CSP actualisé à l'au moins une BS adjacente.
 
7. Procédé selon la revendication 4, dans lequel au moins l'un du temps d'application du CSP actualisé et du nombre d'antennes de la cellule adjacente est transmis à la cellule de desserte conjointement au CSP actualisé.
 
8. Procédé selon la revendication 1, dans lequel l'exécution d'une opération de planification sur la base du CQI multicellulaires reçu, comprenant :

l'utilisation du CQI multicellulaires reçu pour affecter chaque ressource à un UE intracellulaire, qui doit recevoir des données, et pour sélectionner un paramètre de Transmission, TX, et un mode TX de l'UE intracellulaire ;

et la transmission de données en utilisant le mode TX et le paramètre TX sélectionnés.


 
9. Appareil d'exploitation d'une station de base, BS, de desserte (900) dans un système à entrées multiples sorties multiples, MIMO, comprenant la BS de desserte et au moins une BS adjacente, dans lequel chacune de la BS de desserte et l'au moins une BS adjacent est associée à une ou plusieurs cellules, et dans lequel chaque cellule utilise un diagramme de sous-ensemble de répertoire, CSP, pour planifier un équipement d'utilisateur, UE, (910) l'appareil comprenant :

un actualisateur de CSP (902) destiné à déterminer s'il existe ou s'il n'existe pas de BS ayant un CSP actualisé parmi la BS de desserte et l'au moins une BS adjacente ;

un échangeur d'informations intercellulaire (903) destiné à acquérir des CSP de la BS de desserte et l'au moins une BS adjacente en échangeant le CSP actualisé avec l'au moins une BS adjacente, s'il est déterminé qu'il existe une BS ayant le CSP actualisé parmi la BS de desserte et l'au moins une BS adjacente ;

un transmetteur de signal (908) destiné à diffuser le CSP acquis à l'au moins un UE intracellulaire de la BS de desserte, et à transmettre un signal de référence commun, CRS, à l'au moins un UE intracellulaire ;

un processeur d'informations de retour (904) destiné à recevoir un indicateur de qualité de canal, CQI, multicellulaires depuis l'au moins un UE intracellulaire ;

et un sélecteur (906) destiné à exécuter une opération de planification sur la base du CQI multicellulaires reçu, dans lequel le CSP représente un diagramme correspondant à un répertoire pour chaque ressource de temps/fréquence prédéfinie, et dans lequel le répertoire comprend un ensemble vide ou un ensemble d'un ou plusieurs vecteurs précodants, dans lequel l'actualisateur de CSP (902) est configuré pour :

déterminer un ratio d'un débit moyen de cellules par rapport à un débit de limite de cellules ;

comparer le ratio déterminé à une valeur seuil pour générer un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'exécuter une actualisation du CSP ;

transmettre le message de requête d'actualisation de CSP généré à l'au moins une BS adjacente par le biais de l'échangeur d'informations intercellulaire ;

et recevoir le CSP actualisé depuis l'au moins une BS adjacente par le biais de l'échangeur d'informations intercellulaire (903), et dans lequel l'actualisateur de CSP (902) est en outre configuré pour générer le message de requête d'actualisation du CSP en :

générant un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'augmenter une quantité de ressources de répertoire du sous-ensemble quand il est déterminé que le ratio est supérieur à une première valeur seuil ;

générant un message de requête d'actualisation de CSP pour demander à l'au moins une BS adjacente d'augmenter une quantité de ressources de répertoire du sur-ensemble quand il est déterminé que le ratio n'est pas supérieur à la première valeur seuil et est inférieur à une deuxième valeur seuil ;

et ne générant pas de message de requête d'actualisation de CSP quand il est déterminé que le ratio n'est pas supérieur à la première valeur seuil et n'est pas inférieur à une deuxième valeur seuil, dans lequel la première valeur seuil et la deuxième valeur seuil varient en fonction d'une répartition d'UE intracellulaire et d'un type de service d'un UE, dans lequel la deuxième valeur seuil est définie pour être inférieure à la première valeur seuil, et dans lequel un répertoire du sur-ensemble comprend un ensemble de vecteurs précodants incluant tous les vecteurs précodants possibles dans un même répertoire.


 
10. Appareil selon la revendication 9, dans lequel l'actualisateur de CSP est configuré pour :
recevoir, par le biais de l'échangeur d'informations intercellulaire, un message d'accusé ACK/non-accusé, NACK, d'actualisation de CSP pour la requête depuis l'au moins une BS adjacente avant la réception du CSP actualisé depuis l'au moins une BS adjacente.
 
11. Appareil selon la revendication 9, dans lequel au moins l'un du temps d'application du CSP actualisé et du nombre d'antennes de l'au moins une BS adjacente est reçu depuis l'au moins une BS adjacente conjointement au CSP actualisé.
 
12. Appareil selon la revendication 9, dans lequel l'actualisateur de CSP est configuré pour :

actualiser un CSP lors de la réception d'un message de requête d'actualisation de CSP depuis l'au moins une BS adjacente par le biais de l'échangeur d'informations intercellulaire ;

et transmettre le CSP actualisé à l'au moins une BS adjacente par le biais de l'échangeur d'informations intercellulaire.


 
13. Appareil selon la revendication 12, dans lequel l'actualisateur de CSP est configuré pour actualiser le CSP en :

à la réception, par le biais de l'échangeur d'informations intercellulaire, d'un message de requête d'actualisation de CSP pour demander une augmentation d'une quantité de ressources de répertoire du sous-ensemble depuis la cellule adjacente, déterminant si le débit moyen de cellules est supérieur à une valeur seuil et en actualisant le CSP en augmentant la quantité de ressources du répertoire du sous-ensemble dans le CSP quand le débit moyen de cellules est supérieur à la valeur seuil ;

et à la réception, par le biais de l'échangeur d'informations intercellulaire, d'un message de requête d'actualisation de CSP pour demander une augmentation d'une quantité de ressources de répertoire du sur-ensemble depuis la cellule adjacente, en actualisant le CSP en augmentant la quantité de ressources du répertoire du sur-ensemble dans le CSP, dans lequel un répertoire du sur-ensemble comprend un ensemble de vecteurs précodants incluant tous les vecteurs précodants possibles dans un même répertoire.


 
14. Appareil selon la revendication 12, dans lequel l'actualisateur de CSP est configuré pour :
transmettre, par le biais de l'échangeur d'informations intercellulaire, un message d'accusé, ACK/non-accusé, NACK, d'actualisation de CSP à l'au moins une BS adjacente avant la transmission du CSP actualisé à l'au moins une BS adjacente.
 
15. Appareil selon la revendication 12, dans lequel au moins l'un du temps d'application du CSP actualisé et du nombre d'antennes de la cellule adjacente est transmis à la cellule de desserte conjointement au CSP actualisé.
 
16. Appareil selon la revendication 9, dans lequel le sélecteur utilise le CQI multicellulaires reçu pour affecter chaque ressource à un UE intracellulaire , qui doit recevoir des données, et pour sélectionner un paramètre de Transmission, TX, et un mode TX de l'UE intracellulaire , et dans lequel le transmetteur de signal est configuré pour transmettre des données en utilisant le mode TX et le paramètre TX sélectionnés.
 




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Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Non-patent literature cited in the description