WO2013166644A1

WO2013166644A1 - Multi-cell periodic csi reporting

Info

Publication number: WO2013166644A1
Application number: PCT/CN2012/075149
Authority: WO
Inventors: Shuang TAN; Erlin Zeng; Chunyan Gao; Jari Juhani Mattila
Original assignee: Renesas Mobile Corporation
Priority date: 2012-05-07
Filing date: 2012-05-07
Publication date: 2013-11-14

Abstract

It is provided a method, comprising determining, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type; for each of the plural cells, if the priority is high, precoding of the measured channel state indicator to obtain a precoded channel state indicator, else, if the priority is not high, making the precoded channel state indicator the same as the measured channel state indicator; concatenating the precoded channel state indicators to obtain a multi- cell channel state indicator; and providing the multi-channel state indicator for transmitting in a container.

Description

MULTI-CELL PERIODIC CSI REPORTING

Field of the invention

The present invention relates to an apparatus, a method, and a computer program product for multi-cell CSI reporting. More particularly, the present invention relates to an apparatus, a method, and a computer program product for multi-cell periodic CSI reporting.

Background of the invention

Abbreviations

3GPP Third Generation Partnership Project

BER Bit Error Rate

CA Carrier Aggregation

CoMP Coordinated Multiple Point Transmission/Reception

CQI Channel Quality Indicator

CSI Channel State Information

elCIC Enhanced Inter-Cell Interference Cancellation

eNB Evolved NodeB

DL Downlink

FFS for further study

HARQ-ACK Hybrid Automatic Repeat Request - Acknowledgement

Id Identifier

LTE Long-term Evolution

MIMO Multi-Input Multi-Output

MU-MIMO Multiple User MIMO

PMI Precoding Matrix Indicator

PUCCH Physical Uplink Control Channel

PUSCH Physical Uplink Shared Channel

P-CSI Periodic CSI

Rel Release

RI Rank Indicator RM Rate Matching

SR Scheduling Request

SU-MIMO Single User MIMO

TS Technical Specification

UE User Equipment

UL Uplink

In the context of LTE Release 11 work, discussion on the need for uplink (UL) control signaling improvements to support Carrier Aggregation (CA) enhancements has emerged. In LTE Release 11 work, a set of new features have been identified as ways to further improve downlink (DL) performance. Beside Carrier Aggregation, improvements for e.g. CoMP, elCIC, and DL SU-MIMO and MU-MIMO have been proposed and there are great expectations related to achievable performance gains they could promise.

One common nominator for all of these DL features is that their applicability relies heavily on the availability of accurate UL Channel State Information (CSI). While the design of the CSI contents is not a matter of particular interest to "LTE Carrier Aggregation Enhancements" Work Item, the CSI container itself has clearly a significant effect on what kind of CSI can be made available at the eNodeB. The impact of CSI reporting on the overall system performance is twofold. Purely from the DL point of view, the more accurate and elaborate CSI there is available, the better. From the UL point of view, on the other hand, the CSI provides significant overhead by reserving bandwidth that could otherwise be used for data transmission. The efficiency of CSI transmission is expected to become even more critical along with the upcoming CA features and system deployments.

For Re!-10 DL CA, each serving cell is independently configured for periodic CSI reporting, and in the event of a collision of two or more CSI reports, the UE shall drop all but one of the CSI reports. Furthermore, if multi-cell HARQ-ACK feedback collides with a CSI report in a subframe the CSI report is dropped. It was observed that such frequent dropping of periodic CSI (P-CSI) reports could be detrimental to DL throughput [1], [2]. On the other hand it was observed in [3], [4] that aperiodic CSI reporting adequately compensates for most loss in periodic CSI reporting.

The following agreements were achieved at 3GPP RANI #68bis meeting

· Multi-Cell Periodic CSI Multiplexing for DL CA is supported in Rel-11 based on existing UL channel formats (FFS which one)

• Multi-cell HARQ-ACK and Periodic CSI Multiplexing for DL CA is supported in Rel-11

o A Rel-11 UE that supports PUCCH Format 3 can be configured for simultaneous transmission of multi-cell HARQ-ACK feedback, SR and periodic CSI report for one serving cell on PUCCH Format 3; o For a Rel-11 UE that is configured for Format lb with channel selection, simultaneous transmission of multi-cell HARQ-ACK feedback and a periodic CSI report on PUCCH Format 2a/2b is FFS;

o FFS whether separate coding or joint coding of HARQ-ACK and CSI.

In Rel-11 time frame, multi-cell periodic CSI reporting will be supported based on existing uplink channel formats, i.e. PUCCH or PUSCH. Among all the container alternatives, PUCCH format 3 is very attractive due to the largest capacity in all PUCCH formats and being more efficient than PUSCH for periodic CSI reporting. If PUCCH format 3 shall be used for multi-cell periodic CSI reporting, some open questions need to be answered:

• Under the maximum payload size (22 bits) of PUCCH format 3, how many cells' periodic CSI can be actually reported in one subframe is unclear. One option is two cells always, and another option is matching the maximum payload size.

• In Rel-10, only single-ceil periodic CSI feedback via PUCCH is supported. In this case, the different BER requirements of various feedback types, e.g. RI normally needs more reliable performance than CQI/PMI, can be naturally satisfied by employing different size of source bits. However, when combining multi-cell periodic CSI together, multiple reporting types may be transmitted in same PUCCH channel. How to do channel coding in order to adapt different CSI reporting type performance needs considerations.

In Rel-10, PUCCH format 3 is only used for multi-cell HARQ-ACK feedback. In Rel-11 study, multiplexing HARQ-ACK with one cell periodic CSI using PUCCH format 3 was widely discussed and various solutions were also given. So far, to our best knowledge, only the idea of using PUCCH format 3 for multi- cell periodic CSI reporting is proposed. No detailed design is disclosed in public.

References

[1]. Rl-113631, Huawei, "Simultaneous transmission of periodic CSI and HARQ-ACK"

[2]. Rl-113757, ZTE, "Support of simultaneous transmission for periodic CSI and HARQ-ACK"

[3]. Rl-113779, Texas Instruments, "Further Analysis of Multi-Cell Periodic CSI Reporting"

[4]. Rl-113670, Ericsson, "Evaluations of dropping periodic CSI"

Summary of the invention

It is an object of the present invention to improve the prior art.

In particular, it is an object to provide a design of carrying multi-cell periodic CSI using PUCCH format 3.

According to a first aspect of the invention, there is provided an apparatus, comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least a base station of a first radio technology, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to at least perform : determining, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type; for each of the plural cells, if the priority is high, precoding of the measured channel state indicator to obtain a precoded channel state indicator, else, if the priority is not high, making the precoded channel state indicator the same as the measured channel state indicator; concatenating the precoded channel state indicators to obtain a multi-cell channel state indicator; and providing the multi-channel state indicator for transmitting in a container. The apparatus may be used on a terminal side.

According to a second aspect of the invention, there is provided an apparatus, comprising determining means adapted to determine, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type; precoding means adapted to precode, for each of the plural cells, if the priority is high, the measured channel state indicator to obtain a precoded channel state indicator; making means adapted to make, if the priority is not high, the precoded channel state indicator the same as the measured channel state indicator; concatenating means adapted to concatenate the precoded channel state indicators to obtain a multi-cell channel state indicator; and providing means adapted to provide the multi-channel state indicator for transmitting in a container.

According to a third aspect of the invention, there is provided an apparatus, comprising at least one processor, at least one memory including computer program code, and at least one interface configured for communication with at least a user equipment of a first radio technology, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to at least perform : splitting a received multi-cell channel indicator into plural precoded channel state indicators, wherein each of the plural precoded channel state indicators is related to a respective cell identifier; selecting the one of the precoded channel state indicators for which the cell identifier corresponds to a cell represented by the apparatus; determining if a priority related to the selected precoded channel state indicator is high, wherein the priority is based on a respective CSI reporting type; if the priority is high, decoding the selected precoded channel state indicator to obtain a measured channel state indicator; else, if the priority is not high, making the measured channel state indicator the same as the selected precoded channel state indicator; and providing the measured channel state indicator for further evaluation.

The apparatus may be used on a network side.

According to a fourth aspect of the invention, there is provided an apparatus, comprising splitting means adapted to split a received multi-cell channel indicator into plural precoded channel state indicators, wherein each of the plural precoded channel state indicators is related to a respective cell identifier; selecting means adapted to select the one of the precoded channel state indicators for which the cell identifier corresponds to a cell represented by the apparatus; determining means adapted to determine, if a priority related to the selected precoded channel state indicator is high, wherein the priority is based on a respective CSI reporting type; decoding means adapted to decode, if the priority is high, the selected precoded channel state indicator to obtain a measured channel state indicator; making means, adapted to make, if the priority is not high, the measured channel state indicator the same as the selected precoded channel state indicator; and providing means adapted to provide the measured channel state indicator for further evaluation.

According to a fifth aspect of the invention, there is provided a method, comprising determining, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type; for each of the plural cells, if the priority is high, precoding of the measured channel state indicator to obtain a precoded channel state indicator, else, if the priority is not high, making the precoded channel state indicator the same as the measured channel state indicator; concatenating the precoded channel state indicators to obtain a multi- cell channel state indicator; and providing the multi-channel state indicator for transmitting in a container.

The method may be used on a terminal side. The method may be a method of CSI reporting. According to a sixth aspect of the invention, there is provided a method, comprising splitting a received multi-cell channel indicator into plural precoded channel state indicators, wherein each of the plural precoded channel state indicators is related to a respective cell identifier; selecting the one of the precoded channel state indicators for which the cell identifier corresponds to a cell represented by an apparatus performing the method; determining if a priority related to the selected precoded channel state indicator is high, wherein the priority is based on a respective CSI reporting type; if the priority is high, decoding the selected precoded channel state indicator to obtain a measured channel state indicator; else, if the priority is not high, making the measured channel state indicator the same as the selected precoded channel state indicator; and providing the measured channel state indicator for further evaluation.

The method may be used on a network side. The method may be a method of CSI reporting.

According to a seventh aspect of the invention, there is provided a computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any one of the fifth and sixth aspects.

The computer program product may be embodied as a computer-readable medium. According to some embodiments of the invention, at least the following advantages are achieved:

The usage of PUCCH format 3 exploits from the existing HARQ-ACK only transmission to multi-cell CSI transmission. The proposed design has the following advantages:

• Reuse the current PUCCH format 3 coding structure to a large extent

• Satisfy the different performance requirements of various periodic CSI reporting types

• Capable of supporting more than two cell P-CSI feedback as long as the overhead is no more than the maximum PUCCH format 3 payload size It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects to which they refer, unless they are explicitly stated as excluding alternatives.

Brief description of the drawings

Further details, features, objects, and advantages are apparent from the following detailed description of the preferred embodiments of the present invention which is to be taken in conjunction with the appended drawings, wherein

Fig. 1 shows an example of a channel encoding scheme according to an embodiment of the invention;

Fig. 2 shows an apparatus according to an embodiment of the invention; Fig. 3 shows a method according to an embodiment of the invention. Fig. 4 shows an apparatus according to an embodiment of the invention; and Fig. 5 shows a method according to an embodiment of the invention. Detailed description of certain embodiments

Herein below, certain embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein the features of the embodiments can be freely combined with each other unless otherwise described. However, it is to be expressly understood that the description of certain embodiments is given for by way of example only, and that it is by no way intended to be understood as limiting the invention to the disclosed details. Moreover, it is to be understood that the apparatus is configured to perform the corresponding method, although in some cases only the apparatus or only the method are described.

According to embodiments of the invention, a procedure to achieve multi-cell periodic CS1 reporting using PUCCH format 3 is as outlined hereinafter. Fig. l shows the general diagram of the proposed method to multiplex multi-cell periodic CSI into one PUCCH format 3 resource.

• Introduce a pre channel encoder at transmitter (UE) for the cells having the 1^st priority periodic CSI reporting types (e.g. reporting types 3, 5 and 6 comprising RI feedback, see 3GPP TS 36.213 vlO.5.0, chapter 7.2.2)

o Other reporting types do not employ any pre channel encoder o The pre channel encoder(s) could be separate for each cell's P- CSI, or a single joint one for all cells having 1^st priority P-CSI

• Sort all cells' P-CSI following the following rules:

o The 1^st priority reporting types, e.g. reporting types 3, 5 and 6, have higher priority

o For the same reporting type priority

^■ Smaller-length coded (for 1^st priority types) or original (for other priority types) P-CSI has higher priority. For the same coded (for 1^st priority types) or original (for other priority types) P-CSI length, sort according to the cell-IDs (i.e. one of smaller or larger cell-Id has higher priority); or

^■ Sort according to the cell-Ids (i.e. one of smaller or larger cell-ID has higher priority).

• Construct a P-CSI block containing N cells' coded (for 1^st priority types) or original (for other priority types) P-CSI in the order of their priorities o The value N is determined such that the size of N cell P-CSI block is smaller than or equal to the maximum PUCCH format 3 payload size, and the size of N+l P-CSI block is larger than the maximum PUCCH format 3 payload size. Note that the maximum PUCCH format 3 payload size can be fixed or configurable. o The P-CSI of other cells except these N cells will be dropped • This P-CSI block is fed into the legacy PUCCH format 3 encoders and interleavers afterwards.

On the receiver side (eNB), an extra channel decoder is employed for the 1^st priority reporting types after the legacy PUCCH format 3 decoders. The detailed decoding procedure is:

• After the legacy PUCCH format 3 deinterleaver and decoder, estimated concatenated multi-cell CSI block is obtained by receiver (eNB).

• The concatenated P-CSI block is decomposed into multiple single-cell CSI sub-blocks. The size of each sub-block, its reporting type, priority and corresponding cell ID are known by the receiver. Thus, the eNodeB may re-construct the structure of the multi-cell CSI block according to the same CSI sorting principles as the transmitter (UE).

In detail, in embodiments of the invention applied to carrier aggregation, 'cell' means one carrier in frequency domain actually and all 'cells' belong to the same spatial cell, i.e. single eNB. Thus, the eNB is aware of the reporting types, priorities, and corresponding cell IDs.

If embodiments of the invention are applied to CoMP, where CSI reports for multiple spatial cells may be multiplexed in one subframe, these multiple cells may belong to a single (intra-site) or multiple (inter-site) eNBs. In the former case, eNB is anyway aware of the reporting types, priorities, and corresponding cell IDs. In the latter case, eNBs cooperate in order to achieve CoMP gain, and the periodic CSI reporting configuration is shared among these eNBs. Thus, each single eNB is aware of the reporting types, priorities, and corresponding cell IDs, too.

The same principles apply to e.g. elCIC, and DL SU-MIMO and MU-MIMO correspondingly. • For the CSI sub-blocks having the 1^st reporting priority, an extra channel decoder correspond to that on the UE side is used to decode the precoded CSI reporting, thus obtaining the wanted single-ceil CSI reporting. For other reporting priorities, the CSI sub-block is already the wanted single- cell CSI reporting

According to some embodiments of the invention, in case of multi-cell periodic CSI reporting using PUSCH in one subframe, a similar method is used : · Introduce a pre channel encoder at transmitter (UE) for the cells having the 1^st priority periodic CSI reporting types (e.g. reporting types 3, 5 and 6)

o Other reporting types do not employ any pre channel encoder o The pre channel encoder(s) could be separate for each cell's P- CSI, or a single joint one for all cells having 1^st priority P-CSI.

• Construct a P-CSI block containing all cells' coded (for 1^st priority types) or original (for other priority types) P-CSI. · This P-CSI block is further encoded in order to match the payload size of the allocated PUSCH resource

The sorting required for the transmission in PUCCH is not required for the transmission in PUSCH, but may be performed for transmission in PUSCH, too. Alternatively, the sequence may be determined e.g. by the cell Ids (cell indices) only.

At the receiver side (eNB), an extra channel decoder is employed for the 1^st priority reporting types after the PUSCH decoders. The detailed decoding procedure is:

• After the legacy PUSCH deinterleaver and decoder, estimated concatenated multi-cell CSI block is obtained by receiver (eNB) • The concatenated P-CSI block is decomposed into multiple single-cell CSI sub-blocks. The size of each sub-block, its reporting type and corresponding cell ID are known by the receiver, as discussed with respect to transmission in PUCCH. Thus, the eNB may reconstruct the structure of the multi-cell CSI block according to the same CSI sorting principles as the transmitter.

• For the CSI sub-blocks having the 1^st reporting priority, an extra channel decoder is used to decode the precoded CSI reporting, thus obtaining the wanted single-cell CSI reporting. For other reporting priorities, the CSI sub-block is already the wanted single-cell CSI reporting.

An exemplary embodiment of the invention will be explained with reference to Table 1 : In the exemplary embodiment, there is a 5-cell CA scenario as shown in Table 1.

However, in general, the number of cells is not limited to 5 but may be arbitrary.

For a particular subframe, one UE needs to report all 5 cells' periodic CSI to eNB.

The code rate of the pre channel coding for the 1^st priority reporting types (e.g. reporting types 3, 5 and 6) could be assumed 0.5. Thus, robustness of the transmission of these CSIs is enhanced. Then these 5 cells can be sorted according to their priorities, length and cell-ID, as shown in Table 1.

When the maximum pay load size of PUCCH format 3 is 21 bits, the first sorted three cells' P-CSI (cell indices 4, 3, and 2) are selected for transmission, and a size- 16 P-CSI block is constructed. This P-CSI block is fed into the legacy PUCCH format 3 channel encoder and interleaver, and finally mapped into the two time slots. CSIs of cells 1 and 5 are dropped.

Cell Index

in the order of 1 2 3 4 5

cell-ID

Reporting type 2 4 5 3 2b

Original length 8 bits 4 bits 4 bits 2 bits 11 bits

Coded length — — 8 bits 4 bits — Sorting index 4 3 2 1 5

Selected in P-CSI

No Yes Yes Yes No

block

Table 1: An example of Periodic CSI reporting

Fig. 2 shows an apparatus according to an embodiment of the invention. The apparatus may be a terminal such as a UE or a part thereof. Fig. 3 shows a method according to an embodiment of the invention. The apparatus according to Fig. 2 may perform the method of Fig. 3 but is not limited to this method. The method of Fig. 3 may be performed by the apparatus of Fig. 2 but is not limited to being performed by this apparatus. The apparatus comprises determining means 10, deciding means 15, precoding means 20, making means 25, concatenating means 30, and providing means 40.

The determining means 10 determines, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type.

Then, for each of the plural cells, one of the following steps is performed ;

If the priority is high (S15: yes), as decided by the deciding means 15, the precoding means 20 precodes the measured channel state indicator to obtain a precoded channel state ^"indicator (S20). Else, if the priority is not high (S15: no), the making means 25 makes the precoded channel state indicator the same as the measured channel state indicator (S25). The concatenating means 30 concatenates the precoded channel state indicators to obtain a multi-cell channel state indicator (S30). The providing means (40) provides the mu!ti-channe! state indicator for transmitting in a container.

Fig. 4 shows an apparatus according to an embodiment of the invention. The apparatus may be a base station such as an eNB or a part thereof. Fig. 5 shows a method according to an embodiment of the invention. The apparatus according to Fig. 4 may perform the method of Fig. 5 but is not limited to this method. The method of Fig. 5 may be performed by the apparatus of Fig. 4 but is not limited to being performed by this apparatus.

The apparatus comprises splitting means 120, obtaining means 130, selecting means 140, determining means 150, deciding means 155, decoding means 160, making means 165, and providing means 170.

The splitting means 120 splits a multi-cell channel indicator into plural precoded channel state indicators (S120). The multi-cell channel indicator may be received in a container. Each precoded channel state indicator is related to a respective cell. The obtaining means 130 obtains for the precoded channel state indicators the respective cells (S130).

The selecting means 140 selects the one of the precoded channel state indicators for which the cell corresponds to a cell represented by the apparatus, i.e. the eNodeB or NodeB (S140). The determining means 150 determines if a priority related to the selected precoded channel state indicator is high, wherein the priority is based on a respective CSI reporting type (S150). If the priority is high (S155: yes) as determined by the deciding means 155, the decoding means 160 decodes the selected precoded channel state indicator to obtain a measured channel state indicator (S160). If the priority is not high (S155: no), the making means 165 makes the measured channel state indicator the same as the selected precoded channel state indicator (S165). Thus, the measured channel state indicator may correspond to the channel state indicator that would be transmitted if the CSI of this cell would have been transmitted singly.

The providing means 170 provides the measured channel state indicator for further evaluation (S170).

Embodiments of the invention are described based on an LTE system but embodiments of the invention may be applied to other radio access technologies such as WiFi, WLAN, UMTS, HSPA, if multi-cell CSI reporting is foreseen. A device may be a user equipment, a terminal, a mobile phone, a laptop, a smartphone, a tablet PC, or any other device that may attach to the mobile network. A base station may be a NodeB, an eNodeB or any other base station of a radio network.

If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they are differently addressed in their respective network. It does not necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hardware.

According to the above description, it should thus be apparent that exemplary embodiments of the present invention provide, for example a base station apparatus such as a NodeB or an eNodeB, or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s). Furthermore, it should thus be apparent that exemplary embodiments of the present invention provide, for example a controller apparatus such as a user equipment, a UE, or a component thereof, an apparatus embodying the same, a method for controlling and/or operating the same, and computer program(s) controlling and/or operating the same as well as mediums carrying such computer program(s) and forming computer program product(s).

According to exemplari!y embodiments of the present invention, a system may comprise any conceivable combination of the thus depicted devices/apparatuses and other network elements, which are configured to cooperate with any one of them.

In general, it is to be noted that respective functional blocks or elements according to above-described aspects can be implemented by any known means, either in hardware and/or software/firmware, respectively, if it is only adapted to perform the described functions of the respective parts. The mentioned method steps can be realized in individual functional blocks or by individual devices, or one or more of the method steps can be realized in a single functional block or by a single device. Generally, any structural means such as a processor or other circuitry may refer to one or more of the following : (a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) combinations of circuits and software (and/or firmware), such as (as applicable) : (i) a combination of processor(s) or (ii) portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present. Also, it may also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware, any integrated circuit, or the like.

Generally, any procedural step or functionality is suitable to be implemented as software/firmware or by hardware without changing the idea of the present invention. Such software may be software code independent and can be specified using any known or future developed programming language, such as e.g. Java, C+ + , C, and Assembler, as long as the functionality defined by the method steps is preserved. Such hardware may be hardware type independent and can be implemented using any known or future developed hardware technology or any hybrids of these, such as MOS (Metal Oxide Semiconductor), CMOS (Complementary MOS), BiMOS (Bipolar MOS), BiCMOS (Bipolar CMOS), ECL (Emitter Coupled Logic), TTL (Transistor-Transistor Logic), etc., using for example ASIC (Application Specific IC (Integrated Circuit)) components, FPGA (Field-programmable Gate Arrays) components, CPLD (Complex Programmable Logic Device) components or DSP (Digital Signal Processor) components. A device/apparatus may be represented by a semiconductor chip, a chipset, or a (hardware) module comprising such chip or chipset; this, however, does not exclude the possibility that a functionality of a device/apparatus or module, instead of being hardware implemented, be implemented as software in a (software) module such as a computer program or a computer program product comprising executable software code portions for execution/being run on a processor. A device may be regarded as a device/apparatus or as an assembly of more than one device/apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

Apparatuses and/or means or parts thereof can be implemented as individual devices, but this does not exclude that they may be implemented in a distributed fashion throughout the system, as long as the functionality of the device is preserved. Such and similar principles are to be considered as known to a skilled person.

Software in the sense of the present description comprises software code as such comprising code means or portions or a computer program or a computer program product for performing the respective functions, as well as software (or a computer program or a computer program product) embodied on a tangible medium such as a computer-readable (storage) medium having stored thereon a respective data structure or code means/portions or embodied in a signal or in a chip, potentially during processing thereof.

The present invention also covers any conceivable combination of method steps and operations described above, and any conceivable combination of nodes, apparatuses, modules or elements described above, as long as the above- described concepts of methodology and structural arrangement are applicable.

It is to be understood that what is described above is what is presently considered the preferred embodiments of the present invention. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope of the invention as defined by the appended claims.

Claims

WHAT IS CLAIMED IS:

1. An apparatus, comprising

at least one processor,

at least one memory including computer program code, and

at least one interface configured for communication with at least a base station of a first radio technology,

the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to at least perform :

determining, for each of plural cells for which a reporting of a measured channel state indicator is to be performed, a priority of the reporting based on a respective CSI reporting type;

for each of the plural cells, if the priority is high, precoding of the measured channel state indicator to obtain a precoded channel state indicator, else, if the priority is not high, making the precoded channel state indicator the same as the measured channel state indicator;

concatenating the precoded channel state indicators to obtain a multi-cell channel state indicator; and

providing the multi-channel state indicator for transmitting in a container.

2. The apparatus according to claim 1, wherein the processor is configured to perform

determining a maximum length available in the container;

sorting the precoded channel state indicators according to the priorities, wherein the priority of the reporting of a former precoded channel state indicator is higher than the priority of the reporting of a latter precoded channel state indicator, and, if the priorities of two or more reportings are equal, sorting the corresponding precoded channel state indicators according to at least one of a length of the precoded channel state indicator and an identification of the respective cell, thus obtaining a sequence of the precoded channel state indicators; wherein

the concatenating comprises concatenating, according to the sequence, as many precoded channel state indicators as possible to obtain the multi-cell channel state indicator such that a length of the multi-cell channel indicator is not larger than the maximum length.

3. The apparatus according to claim 2, wherein the processor is configured to perform the sorting such that it comprises

sorting the precoded channels state indicators whose corresponding reportings have the same priority according to the lengths of the precoded channel state indicators, wherein the length of a former eel! is shorter than the length of a latter cell;

if two or more of the lengths are equal, sorting these precoded channel state indicators whose corresponding reportings have the same priority and whose lengths are equal according to identifications of their corresponding cells.

4. The apparatus according to claim 2, wherein the processor is configured to perform the sorting such that it comprises

sorting the precoded channels state indicators whose corresponding reportings have the same priority according to identifications of the corresponding cells.

5. The apparatus according to any of claims 2 to 4, wherein the container belongs to a physical uplink control channel.

6. The apparatus according to any of claims 1 to 4, wherein the container belongs to a physical uplink shared channel.

7. The apparatus according to any of claims 1 to 6, wherein the processor is configured to perform :

setting the priority high if the CSI reporting type comprises reporting of a feedback on a rank indicator.

8. A user equipment comprising the apparatus according to any of claims 1 to 7.

9. An apparatus, comprising

at least one processor,

at least one memory including computer program code, and

at least one interface configured for communication with at least a user equipment of a first radio technology, the at least one processor, with the at least one memory and the computer program code, being configured to cause the apparatus to at least perform :

splitting a received multi-cell channel indicator into plural precoded channel state indicators, wherein each of the plural precoded channel state indicators is related to a respective cell identifier;

selecting the one of the precoded channel state indicators for which the ceil identifier corresponds to a cell represented by the apparatus;

determining if a priority related to the selected precoded channel state indicator is high, wherein the priority is based on a respective CSI reporting type; if the priority is high, decoding the selected precoded channel state indicator to obtain a measured channel state indicator;

else, if the priority is not high, making the measured channel state indicator the same as the selected precoded channel state indicator; and

providing the measured channel state indicator for further evaluation.

10. The apparatus according to claim 9, wherein the processor is configured to perform the splitting based on the cell identifiers, the respective CSI reporting types, and respective lengths of the precoded channel state indicators.

11. The apparatus according to any of claims 9 and 10, wherein the processor is configured to perform :

determining that the priority is high if the CSI reporting type comprises reporting of a feedback on a rank indicator.

12. The apparatus according to any of claims 9 to 11, wherein the container belongs to one of a physical uplink control channel and a physical uplink shared channel.

13. A base station comprising an apparatus according to any of claims 9 to 12.

14. A method, comprising

providing the muiti-channel state indicator for transmitting in a container.

15. The method according to claim 14, further comprising

determining a maximum length available in the container;

16. The method according to claim 15, wherein the sorting comprises

sorting the precoded channels state indicators whose corresponding reportings have the same priority according to the lengths of the precoded channel state indicators, wherein the length of a former cell is shorter than the length of a latter cell;

17. The method according to claim 15, wherein the sorting comprises

18. The method according to any of claims 15 to 17, wherein the container belongs to a physical uplink control channel.

19. The method according to any of claims 14 to 18, wherein the container belongs to a physical uplink shared channel.

20. The method according to any of claims 14 to 19, further comprising:

21. A method, comprising

selecting the one of the precoded channel state indicators for which the cell identifier corresponds to a cell represented by an apparatus performing the method;

providing the measured channel state indicator for further evaluation.

22. The method according to claim 21, wherein the splitting is based on the cell identifiers, the respective CSI reporting types, and respective lengths of the precoded channel state indicators.

23. The method according to any of claims 21 and 22, further comprising:

24. The method according to any of claims 21 to 23, wherein the container belongs to one of a physical uplink control channel and a physical uplink shared channel.

25. A computer program product comprising a set of instructions which, when executed on an apparatus, is configured to cause the apparatus to carry out the method according to any one of claims 14 to 24.

26. The computer program product according to claim 25, embodied as a computer-readable medium.