WO2014107904A1

WO2014107904A1 - Channel state information report triggering

Info

Publication number: WO2014107904A1
Application number: PCT/CN2013/070424
Authority: WO
Inventors: Gilles Charbit; Erlin Zeng
Original assignee: Broadcom Corp
Current assignee: Broadcom Corp
Priority date: 2013-01-14
Filing date: 2013-01-14
Publication date: 2014-07-17
Anticipated expiration: 2015-07-14

Abstract

The present invention relates to methods, apparatuses and a computer program product for channel state information report triggering. The present invention includes obtaining, at a user equipment, an uplink grant for a specified uplink subframe via downlink control information, obtaining, at the user equipment, a parameter indicating an uplink subframe offset, causing a transmission of a channel state information report in the specified uplink subframe, and causing a transmission of a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset.

Description

CHAN N EL STATE I N FORMATI ON REPORT TRI GGERI N G

Field of the invention The present invention relates to channel state information (CSI) report triggering, and more particularly, relates to methods, apparatuses and a computer program product for CSI report triggering with reduced DL control overhead for NCT.

Background

Recently, in RAN#51 plenary, a new Release 11 Carrier Aggregation (CA) enhancements working item description (WID) was approved . This includes study NCT (New Carrier Type) including non-backwards compatible elements (cf. documents [1] and [2]).

During the 3GPP (3^rd Generation Partnership Project) RAN (radio access network) Release 12 and onwards workshop, New Carrier Type was identified as a potential feature for further study. A Rel-12 NCT Working Item was contributed to RAN#57 plenary recently (cf. document [3]).

In this document, it is mentioned that "minimizing legacy control signalling and common reference signals reduces the interference and overhead level at low-to- medium loads, allowing for higher end-user throughput and improving system spectral efficiency. This seems especially appealing at the cell edge of homogeneous deployments, in a cell range expansion zone of heterogeneous deployments and for the enhanced local area access in the deployment scenario of low-power nodes with/without coverage of an existing macro-node layer." The NCT will be typically used for small cell deployment. Furthermore, in the RAN#57 meeting there was a study item proposal on physical layer enhancement to local area scenario (cf. document [4]). In the SI (system information) proposal one outstanding topic is the potential enhancements to improve the spectrum efficiency. All the above information provides motivation to study the control overhead reduction in the local area scenario.

As mentioned above, in NCT there is motivation to reduce the DL control overhead . This may be done by applying one DL/UL grant to multiple DL/U L subframes, instead of only one. For example, a U E receives DL grant in subframe #n (denoted with reference sign 11 in Fig . 1), and it can be configured that the same grant applies to subframe #n + l, #n+m, for example, subframes 12 to 14 as illustrated in Fig . 1.

Further, this may be done by transmitting one complete DCI in subframe #n, and transmitting DCI with reduced size in the several following subframes #n + l, #n+m . The reduced-size DCI in subframes #n + l, #n+m only has necessary changes compared to the complete DCI format in subframe #n .

In the local area scenario, these optimization is effective if the channel fading changes slowly and the scheduling decision doesn't have to be change dramatically in the adjacent UL or DL subframes. However, for the first way above, it is clear that aperiodic CSI cannot be triggered in subframe #n + l, #n+m due to the lack of any DL or UL grant for the UE. In current specification, there is dependency between the subframe where CSI trigger is received and the proper CSI reference to use, and the corresponding UL subframe where the aperiodic CSI report can be sent by measuring UE to the serving eN B.

There could be issue with efficiency of aperiodic CSI report if multiple UL grant (#n, #n + l, #n + 2, #n + 3) for the CSI request triggered via DCI format on DL subframe #n-n_CQ, __ref are scheduled (with the CSI RS scheduled on DL subframe #n-n_CQi ret) - This would be wasteful of PUSCH resources. From U L control overhead point of view, it is also desirable to have balanced UL overhead in the set of UL subframes.

In document [5] section 7.2.3, the CSI reference resource is defined as follows : "In the frequency domain, the CSI reference resource is defined by the group of downlink physical resource blocks corresponding to the band to which the derived CQI value relates.

- In the tim e domain, the CSI reference resource is defined by a single

downlink subfram e n-n_CQ, __ref,

o where for periodic CSI reporting n_CQi ret is the smallest value greater than or equal to 4, such that it corresponds to a valid downlink subfram e;

o where for aperiodic CSI reporting n_CQi ret is such that the reference resource is in the sam e valid downlink subfram e as the corresponding CSI request in an uplink DCI format.

o where for aperiodic CSI reporting n_CQi ret is equal to 4 and downlink subfram e n-n cQi ref corresponds to a valid downlink subframe, where downlink subfram e n-n cQi ref is received after the subfram e with the corresponding CSI request in a Random Access Response Grant. "

Hence, for aperiodic CSI report, the CSI reference resource is in the subframe where the CSI triggering is received, e.g ., in subframe n-4 where a U L grant containing a CSI triggering is detected . However, the specifications do not define which U L subframe should be used for the CSI reporting following a CSI request in case of reduced DL control overhead in NCT as outlined in the previous section .

References :

[1] RP- 110451, "LTE CA enhancements WID", RAN 1#54, March 2011

[2] Rl- 100809, "Carrier types offline discussion", Huawei, 3GPP RAN I 59bis [3] RP- 121247, 3GPP Working Item Description, "New Carrier Type for LTE",

RAN#57, Sept. 2012.

[4] RP- 121403 New SI proposal : Small Cell Enhancements for E-UTRA and E- UTRAN - Physical-layer Aspects

[5] 3GPP TS 36.213, "E-UTRA Physical Layer Procedure", vlO.5.0, 2012-03

[6] 3GPP TS 36.331, "E-UTRAN Radio Resource Configuration", vlO.2.0

Summary of the invention According to some embodiments of the invention, there are provided methods, apparatuses and a computer program product for CSI report triggering with reduced DL control overhead for NCT.

Various aspects of exemplary embodiments of the present invention are set out in the appended claims.

According to an exemplary aspect of the present invention, there is provided a method, comprising :

obtaining, at a user equipment, an uplink grant for a specified uplink subframe via downlink control information,

obtaining, at the user equipment, a parameter indicating an uplink subframe offset,

causing a transmission of a channel State information report in the specified uplink subframe, and

causing a transmission of a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset.

According to another exemplary aspect of the present invention, there is provided a method, comprising :

obtaining, at a user equipment, channel state information measurement subframe subsets,

performing, by the user equipment, channel state information measurements at the specified uplink subframes, and

causing a transmission of the channel state information report in the specified uplink subframes. According to another exemplary aspect of the present invention, there is provided a method, comprising :

causing a transmission of downlink control information to a user equipment, the downlink control information indicating a subframe in which an uplink is granted and an uplink subframe offset.

causing a transmission of channel state information measurement subframe subsets to a user equipment,

the channel state information measurement subframe subsets indicating a subset of subframes in which the user equipment performs channel state information measurements and transmits channel state information reports.

According to another exemplary aspect of the present invention, there is provided an apparatus for use in a user equipment, comprising :

at least one processor,

and at least one memory including computer program code,

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

obtaining an uplink grant for a specified uplink subframe via downlink control information,

obtaining a parameter indicating an uplink subframe offset,

transmitting a channel state information report in the specified uplink subframe, and

transmitting a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset.

at least one processor,

and at least one memory including computer program code,

obtaining channel state information measurement subframe subsets, performing channel state information measurements at the specified uplink subframes, and

transmitting the channel state information report in the specified uplink subframes.

According to another exemplary aspect of the present invention, there is provided an apparatus for use in a base station, comprising :

at least one processor,

and at least one memory including computer program code,

transmitting downlink control information to a user equipment,

the downlink control information indicating a subframe in which an uplink is granted and an uplink subframe offset.

at least one processor,

and at least one memory including computer program code,

transmitting channel state information measurement subframe subsets to a user equipment,

According to an exemplary aspect of the present invention, there is provided a computer program product comprising computer-executable computer program code which, when the program is run on a computer (e.g . a computer of an apparatus according to any one of the aforementioned apparatus-related exemplary aspects of the present invention), is arranged to cause the computer to carry out the method according to any one of the aforementioned method- related exemplary aspects of the present invention. Such computer program product may comprise or be embodied as a (tangible) computer-readable (storage) medium or the like on which the computer- executable computer program code is stored, and/or the program may be directly loadable into an internal memory of the computer or a processor thereof.

Advantageous further developments or modifications of the aforementioned exemplary aspects of the present invention are set out in the dependent claims. Brief Description of the Drawings

For a more complete understanding of exemplary embodiments of the present invention, reference is now made to the following description taken in connection with the accompanying drawings in which :

Fig . 1 is a diagram illustrating an example of reduced DL control overhead;

Fig . 2 is a diagram illustrating example of DL and UL signaling for CSI report; Fig . 3 shows a principle flowchart of an example for a method according to certain embodiments of the present invention;

Fig . 4 shows a principle flowchart of another example for a method according to certain embodiments of the present invention;

Fig . 5 shows a principle flowchart of another example for a method according to certain embodiments of the present invention;

Fig . 6 shows a principle flowchart of another example for a method according to certain embodiments of the present invention;

Fig . 7 shows a principle configuration of an example for an apparatus according to certain embodiments of the present invention; Fig . 8 shows a principle configuration of another example for an apparatus according to certain embodiments of the present invention.

Description of exemplary embodiments

Some example aspects of the present invention will be described herein below. More specifically, exemplary aspects of the present are described hereinafter with reference to particular non-limiting examples and to what are presently considered to be conceivable embodiments of the present invention. A person skilled in the art will appreciate that the invention is by no means limited to these examples, and may be more broadly applied.

It is to be noted that the following description of the present invention and its embodiments mainly refers to specifications being used as non-limiting examples for certain exemplary network configurations and deployments. Namely, the present invention and its embodiments are mainly described in relation to 3GPP specifications being used as non-limiting examples for certain exemplary network configurations and deployments. In particular, a LTE-Advanced communication system is used as a non-limiting example for the applicability of thus described exemplary embodiments. As such, the description of exemplary embodiments given herein specifically refers to terminology which is directly related thereto. Such terminology is only used in the context of the presented non-limiting examples, and does naturally not limit the invention in any way. Rather, any other network configuration or system deployment, etc. may also be utilized as long as compliant with the features described herein .

Some embodiments of the invention propose solutions for efficient CSI reporting with reduced DL control overhead on NCT. In particular, some embodiments of the invention propose mechanisms for triggering the Channel State Information (CSI) measurements and CSI report on NCT with reduced control overhead and provide solutions for efficient CSI reporting with reduced DL control overhead on NCT. It is to be noted that the advantages described in the following description are merely specific examples and that of course additional advantages may be achieved.

In summary, some example embodiments of the invention relates to a scenario where one downlink control information can grant multiple downlink or uplink transmissions. In this case, CSI request in DCI format 0/4 will lead to multiple redundant CSI reports in PUSCH. According to the present invention, there is proposed a solution with a parameter of UL-subframe-offset to indicate which subframe should be used for CSI reporting, where UL-subframe-offset can be implicitly derived from C-RNTI, or explicitly indicated in UL grant with CSI request. Additionally, a CSI measurement subframe subset configuration is proposed.

According to a first example embodiment, the CSI report is sent in UL subframe #n + UL-subframe-offset, where the UL grant is given via DCI format in DL subframe #n-n_CQi__ref and an UL subframe offset, UL-subframe-offset, is subsequently applied. The UL-subframe-offset is determined implicitly by a higher-layer configured m-bit C-RNTI-mask as UL-subframe-offset = C-RNTI-mask x C-RNTI ...(1)

According to one example of the first example embodiment, the C-RNTI-mask x C-RNTI masking operation returns the m LSB bits of C-RNTI. In another example of the first example embodiment, a set of possible C-RNTI- mask sequence is predefined, and UE determines UL-subframe-offset based on the detection of the C-NRTI-mask that is applied.

In a second example embodiment, the CSI report is sent in UL subframe #n + UL-subframe-offset, where the UL grant explicitly includes the UL-subframe- offset in spare field in DCI format in DL subframe #n-n_CQi__ref-

In one example embodiment, the RRC configuration may be used to determine UL subframe for CSI reporting. Namely, the UL-subframe-offset may be indicated via higher layer signaling in an optional field in the CQI-ReportConfig RRC IE (cf. document [6], section 6.3.2).

According to a third example embodiment,, the UE is configured via higher-layer with CSI measurement subframe subsets which are subject to different levels of interference from NCT cells. The UE is signaled explicitly the CSI measurement subframe subsets to use for the CSI measurements on the serving NCT cell.

According to the first example embodiment of the invention, an example of the C-RNTI masking operation will be described .

In a first example, it is assumed that a 2-bit C-RNTI mask (m = 2) is used . Further, there are assumed 4 UEs which have the 2 LSB bits in their 16-bit C- RNTI with values 00, 01, 10, 11 respectively. Then, using the formula (1), we have UE# 1, UE#2, UE#3, UE#4 sending their CSI report in UL subframes #n, #n + l, #n+2, #n+3, respectively. In another example, it is assumed that a 3-bit C-RNTI mask is used (m = 3). Further, there are assumed 8 UEs which have the 3 LSB bits in their 16-bit C- RNTI with values 000, 001, 010, 011, 100, 101, 110, 111 respectively. Then, using the formula, we have UE#1, UE#2, UE#3, UE#4, UE#5, UE#6, UE#7, UE#8 sending their CSI report in UL subframes #n, #n + l, #n+2, #n+3, #n+4, #n+5, #n+6, #n+7, respectively.

This way has no impact on DCI overhead, since the UL subframe used for the CSI reporting is implicitly known from the C-RNTI at the UE side and E-UTRAN side.

Alternatively, as already mentioned above, a set of possible C-RNTI-mask sequence is predefined, and UE determines UL-subframe-offset based on the detection of the C-RNTI-mask that is applied . One example is given in the table below. Table 1 : Example of C-RNTI-mask for CSI feedback subframe selection

According to the second example embodiment of the invention, the UL-subframe- offset can be explicitly indicated in U L grant with CSI request. That is, Layer 1 signalling is used to determine the UL subframe for CSI reporting . As an example, assuming UL-subframe-offset may have value in {0, 1, 2, 3}, this results in UE# 1, UE#2, U E#3, U E#4 sending their CSI report in UL subframes #n, #n + l, #n+2, #n+3 respectively.

According to one embodiment, 2 new information bits are introduced in the DCI format. For example, [b0,bl ] are inserted to the DCI format, if reduced control overhead is configured for a U E. Further, it is specified that UE determines the UL subframe for CSI report based on

• b0,bl = 00, aperiodic CSI is transmitted in subframe #n

• b0,bl = 01, aperiodic CSI is transmitted in subframe #n + l

· b0,bl = 10, aperiodic CSI is transmitted in subframe #n + 2

• b0,bl = 11, aperiodic CSI is transmitted in subframe #n + 3

According to another embodiment, existing DCI bits are redefined for the same purpose. For example, the transmit power control field can be redefined to bO and bl in same way as listed above. And the U L power control can be based on DCI format 3/3a if needed . How much DL control signaling reduction can be achieved while ensuring adequate aperiodic CSI reporting depends to some extent on the channel coherence time as illustrated in Fig . 2. The CSI report is used to schedule resources via ePDCCH/PDSCH, which may need reduced reference signal resources. In Fig. 2, 21 denotes a reduced reference signal resource for CSI measurements, 22 denotes subframes where no DL control signaling CSI measurements are performed, 23 denotes UL subframes for CSI report as indicated by UL-subframe-offset, and 24 denotes subframes where there is no CSI report opportunity.

As a minimum requirement to be met, the CSI report triggering, CSI measurements and reporting should be done within a time T < T_coh, where T_coh is the coherence time. Here, at least one reduced reference signal resource should be scheduled within the coherence time, T_coh. This requirement effectively gives a limit to the value of m in the first and second proposal . For example, assume NCT cell is a local cell experiencing a typical coherence time of the order of 10 ms or so. This would give a value of m = 10 subframes for the reduced reference signal periodicity as expressed in subframes. In certain embodiments, eNB only schedules on UL subframe #n+i with i in [0, .., m-1] for a CSI report from a given UE within the scheduling window #n,#n + l,...,#n + m-l . This means no PUSCH resource reserved in multiple UL subframes for a given UE. The first example embodiment is especially efficient from DCI overhead viewpoint, but would require the following to ensure there is no wastage of PUSCH resources for CSI reporting in NCT with reduced DL control overhead :

• There are at least m UEs in the NCT cell (note that up to 2^m UEs may be scheduled based on m-bit C-RNTI-mask ), otherwise some CSI report resources on PUSCH in subframes #n, #n + l, #n + m-l will not be used .

• The eNB MAC needs to allocate the C-RNTI judiciously. The second example embodiment has a good flexibility in balancing the CSI reporting in different UL subframes, as these UL subframe are indicated by UL grant on UL DCI format with the proposed new field addition. Another embodiment relates to the CSI measurement subframe subset configuration.

A neighbour eNB cell may interfere with the serving NCT cell more significantly in subframes where it schedules the reduced reference signal and reduced control signaling . Neighbouring NCT cells may have orthogonal reduced reference signal patterns to mitigate inter NCT cell interference. The measuring UE needs to make CSI measurements that can reflect the different levels of interference from neighbour NCT cells. The UE may then be scheduled according to the CSI report. In an example, the PCell may configure UE with two CSI measurement subframe subsets via higher-layer to measure interference from NCT cells. One CSI measurement subframe subset#l given as subset # 1 = {((SFN + u) mod m), ((SFN + v) mod m), ((SFN + w) mod m)} contains the subframes of neighbour NCT cells likely to cause interference when transmitting their reduced reference signals and reduced control signaling (it is here assumed that the reduced reference signal and reduced control signaling are transmitted in the same subframe).

The parameters u, v, and w have value in [0-9] and u≠ v≠ w. The parameter m is the reduced reference signal periodicity as outlined above. The other subset #2 given as subset #2 = {((SFN+a) mod m), ((SFN + b) mod m), ((SFN + g) mod m)} contains subframes of neighbour NCT cells where only data may be scheduled. The parameters a, b, and g have value in [0-9] and a≠ b≠ ...≠ g and m = 10 in the example. There are 3 subframes assumed to contain the reduced reference signal from 3 neighbour NCT cells. There are 7 subframes assumed to be without reduced reference signal from neighbour NCT cells.

It is noted that each NCT cell may have its own reduced signal reference pattern, which is orthogonal to that of other NCT cells - i.e. orthogonal in time on different subframes or slots. The PCell indicates explicitly to the UE one CSI measurement subframe subset to use for the CSI measurements via a 1-bit field signaled in spare field or in a 1 redefined bit (or redefined existing bit) iO in DCI format in DL subframe #n- nCQI_ref during aperiodic CSI triggering . We have

• iO = 0, the CSI measurement shall base on reference signal in subframe subset # 1

• iO = 1, the CSI measurement shall base on reference signal in subframe subset #2

The PCell makes a decision on which CSI measurement subframe subset the measuring UE should use, may be for example based on the serving cell Identity (ID), the closest neighbour NCT cell IDs, RRM measurements on neighbour NCT cells (e.g. RSRP, RSRQ).

In the considered example, the ambiguity of NCT cells having different reduced reference signal patterns is removed . This ensures that the UE makes CSI measurements in subframes experiencing different levels of interference, for example.

The NCT cells belonging to the same NCT cell group may be configured reduced reference signals orthogonal in frequency on a Resource Element or Resource Block. This helps UE discriminate between NCT cells and mitigate inter-NCT cell interference within an NCT cell group, for example. Certain embodiments of the invention may provide the following advantages for NCT, namely, efficient DL control signaling for CSI triggering and aperiodic CSI reporting, efficient use of PUSH resources for aperiodic CSI reporting, balanced UL control overhead in the set of UL subframes, and inter-NCT cell interference mitigation, for example. However, it is noted that these advantages are merely examples and that certain embodiments of the invention may provide further advantages.

Fig . 3 shows a principle flowchart of an example for a method according to certain embodiments of the present invention. That is, as shown in Fig. 3, this method comprises obtaining, at a user equipment, an uplink grant for a specified uplink subframe via downlink control information in a step S31 and obtaining, at the user equipment, a parameter indicating an uplink subframe offset in a step S32. Further, the method comprises causing a transmission of a channel state information report in the specified uplink subframe in a step S33, and causing a transmission of a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset in a step S34. According to exemplary embodiments oif the present invention, the parameter indicating the uplink subframe offset is determined implicitly by a higher-layer m-bit cell radio network temporary identifier mask.

Alternatively, according to further exemplary embodiments of the present invention, the parameter indicating the uplink subframe offset is included in the downlink control information regarding the uplink grant.

Fig . 4 shows a principle flowchart of another example for a method according to certain embodiments of the present invention. That is, as shown in Fig. 4, this method comprises obtaining, at a user equipment, channel state information measurement subframe subsets in a step S41. Further, the method comprises performing, by the user equipment, channel state information measurements at the specified uplink subframes in a step S42, and causing a transmission of the channel state information report in the specified uplink subframes in a step S43. According to exemplary embodiments of the present invention, the methods as illustrated in Figs. 3 and 4 are implemented in a user equipment located in an LTE or LTE-A based cellular communication network. In this case, the information is transmitted from an evolved node B of the LTE or LTE-A based cellular communication network to a user equipment.

Fig . 5 shows a principle flowchart of still another example for a method according to certain embodiments of the present invention. That is, as shown in Fig. 5, this method comprises causing a transmission of downlink control information to a user equipment in a step S51. The downlink control information indicates a subframe in which an uplink is granted and an uplink subframe offset.

Fig . 6 shows a principle flowchart of still another example for a method according to certain embodiments of the present invention. That is, as shown in Fig. 6, this method comprises causing a transmission of channel state information measurement subframe subsets to a user equipment in a step S61, wherein the channel state information measurement subframe subsets indicate a subset of subframes in which the user equipment performs channel state information measurements and transmits channel state information reports.

According to exemplary embodiments of the present invention, the methods as illustrated in Figs. 5 and 6 are implemented in a communication network control element, in particular an evolved node B of an LTE or LTE-A based cellular communication network.

Fig . 7 shows a principle configuration of an example for a user equipment according to certain embodiments of the present invention. One option for implementing this example for a user equipment according to certain embodiments of the present invention would be a component in a handset such as user equipment UE according to LTE/LTE-A.

Specifically, as shown in Fig. 7, the example for a user equipment 70 comprises at least one processor 71, at least one memory 72 including computer program code and an interface 73 which are connected by a bus 74 or the like. The at least one memory and the computer program code are arranged to, with the at least one processor, cause the user equipment at least to perform obtaining an uplink grant for a specified uplink subframe via downlink control information, obtaining a parameter indicating an uplink subframe offset, transmitting a channel state information report in the specified uplink subframe, an transmitting a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset.

According to another exemplary embodiments of the present invention, the at least one memory and the computer program code are arranged to, with the at least one processor, cause the user equipment at least to perform obtaining channel state information measurement subframe subsets, performing channel state information measurements at the specified uplink subframes, and transmitting the channel state information report in the specified uplink subframes.

For further functions of the user equipment according to further exemplary embodiments of the present invention, reference is made to the above description of methods according to certain embodiments of the present invention, as described in connection with Figs. 3 and 4.

Fig . 8 shows a principle configuration of an example for an apparatus according to certain embodiments of the present invention. One option for implementing this example for an apparatus according to certain embodiments of the present invention would be a base station like an eNB according to LTE/LTE-A.

Specifically, as shown in Fig . 8, the example for an apparatus 80, e.g . an eNB, comprises at least one processor 81, at least one memory 82 including computer program code, and an interface 83 which are connected by a bus 84 or the like. The at least one memory and the computer program code are arranged to, with the at least one processor, cause the apparatus at least to perform transmitting downlink control information to a user equipment, wherein the downlink control information indicates a subframe in which an uplink is granted and an uplink subframe offset.

According to another exemplary embodiments of the present invention, the at least one memory and the computer program code are arranged to, with the at least one processor, cause the user equipment at least to perform transmitting channel state information measurement subframe subsets to a user equipment, wherein the channel state information measurement subframe subsets indicates a subset of subframes in which the user equipment performs channel state information measurements and transmits channel state information reports.

For further functions of the base station, e.g . eNB, according to further exemplary embodiments of the present invention, reference is made to the above description of methods according to certain embodiments of the present invention, as described in connection with Figs. 5 and 6.

In the foregoing exemplary description of the apparatus, e.g. the user equipment or base station (or part of the user equipment or base station e.g. modem), only the units that are relevant for understanding the principles of the invention have been described using functional blocks. The apparatus may comprise further units that are necessary for its respective operation as user equipment and base station, respectively. However, a description of these units is omitted in this specification. The arrangement of the functional blocks of the apparatuses is not construed to limit the invention, and the functions may be performed by one block or further split into sub-blocks. Further, the apparatus, e.g . the user equipment or the base station (or part of the user equipment or base station e.g . modem), may be connected via a link 75/85. The link 75/85 may be a physical and/or logical coupling, which is implementation-independent (e.g . wired or wireless).

According to exemplarily embodiments of the present invention, a system may comprise any conceivable combination of the thus depicted devices/apparatuses and other network elements, which are arranged to cooperate as described above. 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, 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 procedural step or functionality is suitable to be implemented as software 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, system in package (SIP), 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. That is, for example, it is possible to perform the above mentioned timing advance procedure and the connectivity adjustment procedure either individually or in combination.

Even though the present invention and/or exemplary embodiments are described above with reference to the examples according to the accompanying drawings, it is to be understood that they are not restricted thereto. Rather, it is apparent to those skilled in the art that the present invention can be modified in many ways without departing from the scope of the inventive idea as disclosed herein.

Abbreviations:

CA Carrier Aggregation

CC Component Carrier

C-RNTI Cell Radio Network Temporary Identifier

CRS Cell-specific Reference Signal

CSI RS Channel State Information Reference Signal DCI Downlink Control Information

DL Downlink

DM RS Demodulation Reference Signal eNB Enhanced Node B

LTE Long Term Evolution

LTE-A Long Term Evolution Advanced

NCT New Carrier Type

PDCCH Physical Downlink Control Channel

PDSCH Physical Downlink Shared Channel

RCRS Reduced Common Reference Signal

RRC Radio Resource Control

RRM Radio Resource Management

RS Reference Signal

SI System Information

SFN System Frame Number

UE User Equipment

UL Uplink

TD Time Domain

WID Working Item Description

Claims

W HAT I S CLA I M ED I S:

1. A method, comprising :

2. The method according to claim 1, wherein

the parameter indicating the uplink subframe offset is determined implicitly by a higher-layer m-bit cell radio network temporary identifier mask.

3. The method according to claim 1, wherein

the parameter indicating the uplink subframe offset is included in the downlink control information regarding the uplink grant.

4. A method, comprising :

causing a transmission of the channel state information report in the specified uplink subframes.

5. The method according to any one of claims 1 to 4, wherein the method is implemented in a user equipment located in a Long Term Evolution or Long Term Evolution Advanced based cellular communication network.

6. A method, comprising : causing a transmission of downlink control information to a user equipment,

7. A method, comprising :

8. The method according to any one of claim 6 or 7, wherein the method is implemented in a base station located in a Long Term Evolution or Long Term Evolution Advanced based cellular communication network.

9. An apparatus for use in a user equipment, comprising :

at least one processor,

and at least one memory including computer program code,

obtaining a parameter indicating an uplink subframe offset,

10. The apparatus according to claim 9, wherein

11. The apparatus according to claim 9, wherein

12. An apparatus for use in a user equipment, comprising :

at least one processor,

and at least one memory including computer program code,

13. The apparatus according to any one of claims 9 to 12, wherein the apparatus is implemented in a user equipment located in a Long Term Evolution or Long Term Evolution Advanced based cellular communication network.

14. The apparatus according to any one of claims 9 to 12, wherein

the apparatus comprises a user equipment.

15. An apparatus for use in a base station, comprising :

at least one processor,

and at least one memory including computer program code,

transmitting downlink control information to a user equipment,

16. An apparatus for use in a base station, comprising :

at least one processor,

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

17. The apparatus according to claim 15 or 16, wherein the apparatus is implemented in a base station located in a Long Term Evolution or Long Term

Evolution Advanced based cellular communication network.

18. The apparatus according to claim 15 or 16, wherein

the apparatus comprises a base station.

19. An apparatus, comprising :

means for obtaining an uplink grant for a specified uplink subframe via downlink control information,

means for obtaining a parameter indicating an uplink subframe offset, means for transmitting a channel state information report in the specified uplink subframe, and

means for transmitting a channel state information report in additional subframes determined based on the specified uplink subframe and the parameter indicating the uplink subframe offset.

20. An apparatus, comprising :

means for obtaining channel state information measurement subframe subsets,

means for performing channel state information measurements at the specified uplink subframes, and

means for transmitting the channel state information report in the specified uplink subframes.

21. An apparatus, comprising : means for transmitting downlink control information to a user equipment, the downlink control information indicating a subframe in which an uplink is granted and an uplink subframe offset.

22. An apparatus, comprising :

means for transmitting channel state information measurement subframe subsets to a user equipment,

23. A computer program product comprising computer-executable computer program code which, when the program is run on a computer, is arranged to cause the computer to carry out the method according to any one of claims 1 to 8.

24. The computer program product according to claim 23, embodied as a computer-readable storage medium.