GB2562053A - Improvements in and relating to telecommunication systems - Google Patents

Abstract

A method of operating Non Coherent Joint Transmission (NCJT) in a telecommunications network comprising at least one User Equipment (UE) 10 and two cooperating Transmission Points (TPs) 20,30, comprising at least one operational mode defining at least one set of possible resource allocation schemes. The method may comprise a plurality of operational modes defining permitted combinations of transmission such as fully overlapped or non-overlapped resource allocations where other UEs may or may not be served on the same resource. Further channel state measurement (CSI) requirements may be defined such that information such as CQI, PMI, PTI, CRI or RI may be fed back from the UE aperiodically or with a defined periodicity wherein a sequential hybrid report is sent comprising baseline information with additional information provided in a cyclic manner where the cooperating TPs may be operable to determine missing CSI information on the basis of the received CSI information.

Description

(71) Applicant(s):

Samsung Electronics Co., Ltd.

129, Samsung-ro Yeongtong-gu, Suwon-si, Gyeonggi-do 16677, Republic of Korea (72) Inventor(s):

Mohammed Al-lmari Yinan Qi

Louis Christodoulou (74) Agent and/or Address for Service:

Appleyard Lees IP LLP

Clare Road, HALIFAX, West Yorkshire, HX1 2HY, United Kingdom (51) INT CL:

H04L 5/00 (2006.01) H04W 72/04 (2009.01) (56) Documents Cited:

WO 2013/136777 A1 US 20140192734 A1 XP051243137 Enhancement to CSI feedback for NCJT 3GPP TSG RAN WG1 #88bis R1-1705006 April 3rd - 7th, 2017 Spokane, USA (58) Field of Search:

INT CL H04B, H04L, H04W

Other: WPI, EPODOC, TXTE, XPI3E, XPIEE, XP3GPP (54) Title of the Invention: Improvements in and relating to telecommunication systems

Abstract Title: A Non Coherent Joint Transmission system comprising operational modes defining sets of possible resource allocation schemes (57) A method of operating Non Coherent Joint Transmission (NCJT) in a telecommunications network comprising at least one User Equipment (UE) 10 and two cooperating Transmission Points (TPs) 20,30, comprising at least one operational mode defining at least one set of possible resource allocation schemes. The method may comprise a plurality of operational modes defining permitted combinations of transmission such as fully overlapped or nonoverlapped resource allocations where other UEs may or may not be served on the same resource. Further channel state measurement (CSI) requirements may be defined such that information such as CQI, PMI, PTI, CRI or Rl may be fed back from the UE aperiodically or with a defined periodicity wherein a sequential hybrid report is sent comprising baseline information with additional information provided in a cyclic manner where the cooperating TPs may be operable to determine missing CSI information on the basis of the received CSI information.

Non*Coh@rsnt Joint Transmission

Fig. 1b

1/3

Fig. 1b

2/3

Transm. to UE1

Transm. to another UE or blank

Pl TP2

Fully

Overlapped

Partially

Overlapped

TPl		ΓΡ2 J
	Not

Overlapped

Fig. 2

PRB

TPl/ TP2/ UEI _: UE1

Interf. Type 1

TPl/	TP2/
UEI	Blank

Interf. Type 2

TPl/ TI’2/ Blank UEI Interf. Type 3

Interf. Type 4

Fig. 3

	TP2/
	UEI

Interf. Type 5

3/3

Included in Interference report

- Baseline Report

- Additional Report

Fig. 4

UE

Fig. 5

Improvements in and relating to telecommunication systems [0001] The present invention relates to improvements in the operation of telecommunication systems, particularly cellular telecommunication systems and more particularly, cellular telecommunication systems which operate in a non-coherent joint transmission (NCJT) mode.

[0002] Non-Coherent Joint Transmission (NCJT) refers to a transmission scheme where transmission of the ΜΙΜΟ layer(s) is performed from two or more transmission points (TPs) without adaptive precoding across the TPs. In NCJT, precoding is applied individually to the TX antennas belonging to each TP. In other words, a UE would receive M transmissions which are each precoded by a N₇/Rank, precoding matrix where Rank/ is the rank from the /^h TP participating in the JT. Figure 1 illustrates the difference between NCJT and coherent joint transmission.

[0003] Figures 1 a and 1 b show systems operating in Coherent Joint Transmission (CJT) and Non-Coherent Joint Transmission (NCJT) modes respectively. Figures 1a and 1b each show a UE 10, in communication with 2 TPs 20, 30, each of which is further connected to a Core Network 40.

[0004] The requirements on the network operation for coherent and non-coherent JT are quite different. While both require a low latency backhaul connection, NCJT only requires sharing of the control information (e.g.: MCS, RB assignment, rank, etc) between the two TPs involved in the NCJT operation. Data does not necessarily need to be shared between the two TPs since each TP is transmitting different data as shown in Figure 1b. Compared to NCJT, coherent JT requires the downlink data to be shared among the two TPs - TP A and TP B. This requirement is necessary since both TPs are transmitting signals representing the same data. Being able to operate without having to share data between TPs is a significant benefit for networks where the backhaul bandwidth is limited. This is why NCJT is considered advantageous in certain situations.

[0005] As with coherent JT, NCJT can be supported using the existing specification. However, it is predicted that there will be limitations on the performance since the current specification was not designed with NCJT in mind.

[0006] Embodiments of the present invention aim to address problems associated with the implementation of NCJT in a cellular telecommunication network.

[0007] According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.

[0008] Although a few preferred embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims.

[0009] For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example only, to the accompanying diagrammatic drawings in which:

[0010] Figures 1a and 1b show typical network configurations for Coherent Joint Transmission (JCT) and Non Coherent Joint Transmission (NCJT) respectively;

[0011] Figure 2 shows examples of different resource allocations in NCJT with 2 TPs;

[0012] Figure 3 shows examples of different interference types associated with different resource allocations;

[0013] Figure 4 shows a table illustrating Sequential Hybrid Reporting (SHR); and [0014] Figure 5 shows an example signal flow associated with an embodiment of the invention.

[0015] One of the problems involved in implementing NCJT successfully is concerned with the Channel State Information (CSI) process. In the current specification, CSI is optimized per CSI process. Therefore, a UE can be configured to report back CSI optimized for single TP transmission or optimized for coherent JT from multiple TPs. However, it is not possible to configure the UE to report back CSI that is optimized for non-coherent JT from multiple TPs, as shown in Figure 1 b. Such a CSI needs to take into account the fact that each TP will generate different sets of DMRS ports and reflect that in choosing the preferred transmission parameters (e.g. precoding, CQI, rank etc.) for the TPs involved in non-coherent JT.

[0016] One of the consequence of transmitting different data from different TPs in NCJT is that there is no need to keep the Resource Block (RB) allocation identical between two TPs. This is shown in Figure 2, which illustrates three different possible schemes:

[0017] Scheme 1 (Fully Overlapped), where the resource allocations from different TPs for a UE are fully overlapped. This is shown by the resource allocations from TP1 and TP2 being targeted at UE1 simultaneously. In other words, for each of PRB#1 - PRB#5, TP1 and TP2 are transmitting to UE1.

[0018] Scheme 2 (Partially Overlapped), where the resource allocations from different TPs for a UE are partially overlapped. This is shown in the resource allocations for PRB#1 and PRB#2 where TP1 is shown to be transmitting to another UE (i.e. not UE1) or is blank, while TP2 is transmitting to UE1. In PRB#4 and PRB#5, the situation is reversed, where TP1 is transmitting to UE1 while TP2 is transmitting to another UE or is blank. In PRB#3, transmissions from TP1 and TP2 are aimed at UE1.

[0019] Scheme 3 (Not overlapped), where the resource allocations from different TPs for a UE are not overlapped. This is shown in the resource allocations for PRB#1 and PRB#2 where TP1 is shown to be transmitting to another UE (i.e. not UE1) or is blank, while TP2 is transmitting to UE1. In PRB#3, PRB#4 and PRB#5, the situation is reversed, where TP1 is transmitting to UE1 while TP2 is transmitting to another UE or is blank. There are no PRBs where TP1 and TP2 are both transmitting to UE1 simultaneously.

[0020] In NCJT, the UE can suffer from different interference types based on the overlapping of the resources allocated to the UE by the two TPs and the transmission on these resources. So, in each Physical Resource Block (PRB), or group of PRBs, the interference type can be one of:

[0021] Interference Type 1 [0022] Interference Type 2 [0023] Interference Type 3 [0024] Interference Type 4 [0025] Interference Type 5

Both TP1 and TP2 are transmitting to UE1

TP1 is transmitting to UE1 and TP2 is silent

TP1 is silent and TP2 is transmitting to UE1

TP1 is transmitting to UE1 and TP2 is transmitting to another UE

TP1 is transmitting to another UE and TP2 is transmitting to UE1 [0026] These different interference types are illustrated in Figure 3.

[0027] To make an appropriate scheduling decision, the coordinating TPs require the necessary channel state information (CSI) to perform the scheduling and resource allocation for the UE. Two CSI-RS (Channel State Information-Reference Signals) resources and three CSI-IM (Channel State Information-Interference Measurement) resources are required to measure all the possible channel and interference types. These resources are as set out below:

• A first CSI-RS resource to estimate the channel part of TP1;

• A second CSI-RS resource to estimate the channel part of TP2;

• A first CSI-IM resource to estimate the interference from out of the cooperating set of TPs, corresponding to interference types 1,2 and 3;

• A second CSI-IM resource to estimate the interference corresponding to interference type 4; and • A third CSI-IM resource to estimate the interference corresponding to interference type 5.

[0028] CSI-RS is similar to a pilot or training signal and allows the UE to perform a channel estimation on the basis of receiving a known transmission.

[0029] CSI-IM is essentially an empty transmission which allows the UE to measure interference from other sources while the TP is silent.

[0030] A CSI report can consist of channel quality indicator (CQI), precoding matrix indicator (PMI), precoding type indicator (PTI), CSI-RS resource indicator (CRI), and/or rank indication (Rl). For example, UE1 will feedback the following CSI if all the resource allocations (as shown in Figure 2) are allowed:

• PMI (ΙΦΤ): selected precoding matrix for TP1.

• PMI (14//): selected precoding matrix for TP2.

• CQIi^P1: The CQI of TP1 if TP2 transmits to UE1 on the same PRB using the selected precoding matrix (14//).

• CQI₂ ^P1: The CQI of TP1 if TP2 is not transmitting to UE1 on that PRB.

• CQIJP¹: The CQI of TP1 if TP2 transmits to another UE on the same PRB using the precoding matrix (14/,) that is different from the selected precoding matrix (14//).

• CQIi^P2: The CQI of TP2 if TP1 transmits to UE1 on the same PRB using the selected precoding matrix (14//).

• CQI₂ ^P2: The CQI of TP2 if TP1 is not transmitting to UE1 on that PRB.

• CQIJP²: The CQI of TP2 if TP1 transmits to another UE on the same PRB using the precoding matrix (14/J that is different from the selected precoding matrix (14//).

[0031] The following equations illustrate the relation between the different CQI types and the interference types:

H₂W$ + I + Nj

CQI?ⁿ

CQI^PPi

HiW( \ HzWz + I + Nj

CQI

T'P'2 rTP2

Π.+Ν λ IIA Vf + I + N) liCY+\ i 1 rTP'l ll+\+ \ //: ill + I + .V J where I is the interference from the TPs outside the cooperation set, and N is the noise.

[0032] As is clear from the preceding description, NCJT operation can require a high level of resources support for operating the CSI-RS/CSI-IM and feedback overhead.

[0033] Embodiments of the present invention relate to an operation mode for NCJT that defines the operation of the scheme in terms of the permissible resource allocations and the required CSI resources and feedback. Compared to the prior art scenario where no operation modes are defined, embodiments of the invention can reduce the required CSI resources and feedback overhead.

[0034] Embodiments of the invention introduce operation modes for NCJT, where, an operation mode may define either all or a subset of possible (permitted) resource allocation schemes. By doing so, the required CSI resources and overhead introduced by feedback can be reduced commensurate with specific requirements. Provided below are exemplary details of operation modes. Other modes may be defined by amalgamating certain features of the modes described. Still further modes may be defined as required and as understood by those skilled in the art. In one embodiment of the present invention, a single operational mode is defined in NCJT mode, which defines a certain set of resource allocations. This single mode, which may be considered a default mode may be defined to correspond to one of the following operation modes or may be defined differently as required. In another embodiment, a plurality of operational modes are defined, each defining a set of possible resource allocations. Examples of a plurality of operational modes include:

[0035] Operation mode 1 (OpM1): All resource allocations are possible and other UEs can be served on the same resources allocated to UE1 (UE1 will report all the possible interference types, as illustrated in Figure 3 since, in principle, any of these interference types may arise).

[0036] Operation mode 2 (OpM2): All resource allocations are possible and NO other UEs can be served on the same resources allocated to UE1, avoiding interference types 4 and 5 (i.e. second and third CSI-IM resources are not needed). Also, the UE does not need to report back CSI for interference types 4 and 5 (i.e. CQIJP¹, CQIJp²).

[0037] Operation mode 3 (OpM3): Fully overlapped resource allocation only (the UE needs to feedback interference type 1 only, since interference types 2-5 will not arise).

[0038] Operation mode 4 (OpM4): Non-overlapped resource allocation only and other UEs can be served on the same resources allocated to UE1 (the UE does not need to feedback interference type 1).

[0039] Operation mode 5 (OpM5): Non-overlapped resource allocation only and other UEs cannot be served on the same resources allocated to UE1 (the UE does not need to feedback interference types 1,4 and 5, since these cannot arise).

[0040] The example operation modes are shown in the table below (Table 1).

	Resource Allocation	Serve other UEs on same resource	Interference Type Reported
1	2	3	4	5
OpM1	All Permitted	Permitted	R	R	R	R	R
OpM2	All Permitted	Not Permitted	R	R	R
OpM3	Fully Overlapped Only	-	R
OpM4	Non Overlapped Only	Permitted		R	R	R	R
OpM5	Non Overlapped Only	Not Permitted		R	R

TABLE 1 [0041] For each NCJT operation mode, set out above, there are corresponding :

1) Permissible resource allocation options;

2) Required CSI-RS/CSI-IM resources for CSI measurements; and

3) CSI feedback schemes: Which the UE uses to calculate the CSI reports and feedback to the cooperating TPs [0042] The following passages set out the main steps involved in a method according to an embodiment of the invention:

1. The NCJT operation is selected dynamically by: a) joint decision by the cooperating TPs; or b) by one TP (e.g. master TP) in the cooperating set of TPs. Note that in this description, an example of two cooperating TPs is described for simplicity, but the principle extends to any number of cooperating TPs operating in NCJT mode.

2. The NCJT operation mode can be selected based on several aspects, such as the signaling/feedback overhead, resources utilization, users’ complexity, or other parameter of interest.

3. The selected NCJT operation mode will be signaled among the cooperating TPs using, for example, an X2 Interface. This is shown as Step 1 in Figure 5.

4. The selected NCJT operation mode will be signaled to the UE using higher layers, such as RRC or MAC. This may require the introduction of a new indicator/trigger field. This is shown as Step 2 in Figure 5.

In NCJT mode, the CSI reporting mode can be signaled to the UE from only one of the cooperating TPs, CSI-RS and CSI-IM need to be transmitted from both (or all) cooperating TPs.

As such, there are 2 instances labeled Step 2 in Figure 5. The first shown with a solid line indicates a signal from TP 1 to the UE and the second, shown with a dotted line indicates a signal from TP2 to the UE. The dotted line indicates that at least part of the information of Step 2 (NCJT mode, CSI-RS/CSI-IM configurations and CSI reporting mode) is transmitted to the UE from the other cooperating TPs - TP2 in this example.

5. The UE will be configured with CSI-RS and CSI-IM resources based on the selected NCJT operation mode. This is also covered by Step 2 in Figure 5, which indicates that the TPs (or one TP) needs to signal to the UE the selected NCJT mode and the CSI reporting mode. In addition, all the TPs need to configure the UE with the relevant CSI-RS/CSI-IM resources required for this NCJT mode, which requires informing the UE where, in frequency and time, the CSI-RS/CSI-IM will be transmitted.

6. The UE will calculate the CSI reports that are optimized for the selected NCJT operation mode using the CSI-RS and CSI-IM resources.

7. The UE will feedback the CSI reports based on the feedback mode corresponding to the selected NCJT operation mode. This is shown as Step 3 in Figure 5.

8. The cooperating TPs will allocate the resource for downlink transmission based on the selected NCJT operation mode.

[0043] With less frequent periodicity, or aperiodically, the network may require a full set of CSI measurements and reports be produced to establish if the currently selected operation mode has become sub-optimal for the given scenario. This may be achieved in a number of ways, examples of which follow.

[0044] A first approach is that a more complete or full (i.e. OpM1) report is performed in place of a reduced report, at a reduced frequency. This could be performed every n reports, where n may be defined by the network as required.

[0045] This is achieved with a semi static agreement, whereby the cooperating TPs configure the UE statically or semi-statically. Each UE may be configured with an offset, distributing larger reports overtime.

[0046] An example configuration structure may include the following:

NCJT-Mode-AdditionalReporting : AdditionalReport-AllocPeriod rl28},

AdditionalReport-AllocOffset

SEQUENCE {

ENUMERATED {r2, r4, r8, rl6, r32, r64,

INTEGER ¢0.. AllocPeriod-1),

AdditionalReport-OpMode }

INTEGER (0

N_Modes),

OPTIONAL [0047] The allocation period is defined per report, i.e. an allocation period of 2 will result in every second report containing additional information. Requesting the additional reporting mode is optional, with the UE defaulting to OpM1 (Full Reporting) if undefined.

[0048] A second approach requires that with each measurement and report in the currently defined operation mode (Apart from OpM1 (Full Reporting)), one or more additional measurements are made and included in the feedback. This allows the network to aggregate these reports in lieu of a single full report.

[0049] This is facilitated with the use of a Sequential Hybrid Reporting (SHR) operation mode. Each SHR mode is focused on a providing the same operation mode as its equivalent static mode and is selected and communicated to the UE in the same manner. The SHR mode will, in a pre-determined manner known to both the TP and UE, cycle through the otherwise missing measurements and report these back in each report. This allows the network to continually update its assessment of the UEs current operation mode, deducing its optimality for the current scenario at.

[0050] The allocation strategy of CSI-RS/CSI-IM resources will be determined by the cooperating TPs and can be either explicitly communicated to the UE or determined a priori given the configuration parameters.

[0051] Figure 4 shows an example of SHR reporting mode with full operational equivalence to OpM5 i.e. full (baseline) reports are provided for Type 2 and Type 3 interference each reporting period, with additional reports for interference types 1,4 and 5 provided as shown in the table in a cyclical manner. In all reporting periods, interference reports type 2 and 3 are reported. Every third reporting period on of interference reports 1, 4 or 5 are additionally provided. In reporting periods 1, 4, 7, 10, 13 etc., interference type 1 is reported; in reporting periods 2, 5, 8,11, 14 etc., interference type 4 is reported; and in reporting periods 3, 6, 9, 12, 15 etc., interference type 5 is reported.

[0052] In a third approach, the cooperating set of TPs may request a full measurement and report aperiodically. This may be requested if there is a change in operating conditions or environment e.g. UE attachment, detachment or sudden change in network conditions.

[0053] In addition to the three approaches set out above, the network may manually trigger an additional (full or selective) measurement and report at any time by sending a suitable request message.

[0054] In instances where an operating mode with high feedback overhead is selected (e.g. OpM1), it is possible for the network to permit the UE to carry out partial reporting at its own discretion. In this case, on conducting a full measurement for the currently selected operation mode (OpM), the UE may establish a subset of possible scheduling schemes to be clearly suboptimal, dropping this information from its feedback report to the TP. This results in an overall reduction of feedback overhead. For example, if the UE is configured with OpM1 and with ‘UE-selected full/partial feedback’, the UE can feedback all the corresponding CSI for this specific operation mode or a subset of the CSI.

[0055] One alternative is to do “wideband” selection of the feedback, in which the selected feedback mode/type is for all the subbands (a subband can consist of one or more resource blocks) that are configured with CSI measurement (CSI-RS/CSI-IM). Another option is to do per-subband feedback selection, where the UE selects the feedback mode for each subband independently.

[0056] The UE can inform the cooperating TPs about the selected feedback mode using an indicator (wideband or per-subband).

[0057] In a situation when the UE is not configured to measure all the interference types, (e.g. not configured with OpM1 or the UE fed back part of the report), the base-station can infer or deduce the missing channel state information from the reported ones.

[0058] For example, if the UE fed back to TP1, CQlI^P1 and CQip¹ but notCQIJP¹, the basestation (TP1) can estimate the value of CQIJP¹ using CQip¹ and/or CQlI^P1. Given that CQip¹ reflects the channel quality when TP2 is silent (not transmitting on that specific subband), CQl3^P1 will be smaller (or equal if l+N are relatively large) than CQIJ^P1. Thus, it be calculated at follows: CQIJ ^P1 = CQl2^P1 - K, where K is a back-off value, which may be determined by the network, based on measurements, simulations or analytical evaluations.

[0059] Embodiments of the invention provide flexibility in the operation of an NCJT scheme. Instead of fixing the resource allocation scheme to allow all the resource allocation options or restricting it to a specific set of resource allocation options, the NCJT setup can be allowed to operate through different defined operation modes (OpM).

[0060] Each operation mode has its associated permissible resource allocation options, required CSI-RS/CSI-IM resources for CSI measurements and CSI feedback schemes. By allowing NCJT to operate in different operation modes, the operation mode can be selected to optimize the scheme performance.

[0061] Further, there are direct savings in terms of required CSI resources and feedback overhead. In addition, embodiments introduce procedures for UE-selected feedback modes that allow the UE to feedback part of the channel state information based on the expected performance. Embodiments further introduce a method relating to how to calculate or infer the missing channel state information (e.g. CQI for some interference types) based on the reported channel state information.

[0062] At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component’, ‘module’ or ‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, objectoriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

[0063] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0064] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

[0065] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0066] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (16)

1. A method of operating in Non Coherent Joint Transmission, NCJT, mode in a telecommunication network comprising at least one User Equipment, UE, and two cooperating Transmission Points, TP, the method comprising at least one operational modes, each at least one operational mode defining at least one set of possible resource allocation schemes.

2. The method of claim 1 wherein the method comprises a plurality of operational modes, each operation mode defining at least one set of possible resource allocation schemes.

3. The method of claim 2 wherein each operational mode defines permitted combinations of transmission to the at least one UE from the two cooperating TPs operating in NCJT mode.

4. The method of claim 3 further defining channel state measurement requirements for the at least one UE, whereby said measurements are fedback to at least one of the cooperating Transmission Points.

5. The method of any one of claims 2 to 4 wherein the plurality of operational modes comprise one or more of:

a first operational mode, OpM1 where all resource allocations are permitted and other UEs may be served on the same resource;

a second operational mode, OpM2, where all resource allocations are permitted and other UEs may not be served on the same resource;

a third operational mode, OpM3, where fully overlapped resource allocations are permitted;

a fourth operational mode, OpM4, where non overlapped resource allocations are permitted and other UEs may be served on the same resource; and a fifth operational mode, OpM5, where non overlapped resource allocations are permitted and other UEs may not be served on the same resource.

6. The method of any preceding claim wherein NCJT operation is selected either by a joint decision of the cooperating TPs or by one of the cooperating TPs, acting as master.

7. The method of claim 6 wherein the decision may be based on one or more of signalling or feedback overhead, resource utilisation and users’ complexity.

8. The method of claim 6 or 7 wherein information on NCJT operation is shared between cooperating TPs using an interface between the TPs.

9. The method of any of claims 6, 7 or 8 wherein information on NCJT operation is signalled to the at least one UE using higher layer signalling.

10. The method of any of claims 6 to 9 wherein channel state transmissions are sent from each of the cooperating TPs to the at least one UE to permit it to make measurements and feedback, according to resources which have been allocated by the TPs.

11. The method of any of claims 4 to 10 wherein the channel state measurements are fed back from the at least one UE aperiodically or with a defined periodicity.

12. The method of claim 11 wherein the channel state measurements are fed back in one of the following manners: a full report is provided at a reduced frequency; a sequential hybrid report is fed back comprising certain baseline information in each reporting period with additional information provided in a cyclic manner; and a full report is provided from the at least one UE when requested by one of the cooperating TPs.

13. The method of any of claims 4 to 12 wherein at least one of the cooperating transmissions points is operable to determine missing channel state information on the basis of channel state information which has been received.

14. A UE operable to perform the method according to any of the preceding claims.

15. A TP operable to perform the method according to any of claim 1 to 13.

16. A telecommunication system, comprising at least one UE and two cooperating TPs to perform the method of any of claims 1 to 13.

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