WO2010124721A1

WO2010124721A1 - Optimized resource allocation signaling on a physical downlink control channel

Info

Publication number: WO2010124721A1
Application number: PCT/EP2009/055087
Authority: WO
Inventors: Frank Frederiksen; Carsten Ball; Mieszko Chmiel; Wolfgang Payer
Original assignee: Nokia Siemens Networks Oy
Priority date: 2009-04-27
Filing date: 2009-04-27
Publication date: 2010-11-04

Abstract

According to several embodiments of the present invention, a downlink control information format is monitored or created, wherein downlink control information format is a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel. Alternatively, the downlink control information format may be a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel. Also further downlink control information formats are proposed.

Description

Optimized resource allocation signaling on a physical downlink control channel

Field of the Invention

The present invention relates to an apparatus, method and computer program product for an optimized resource allocation signaling on a physical downlink control channel .

Related background Art

The following meanings for the abbreviations used in this specification apply:

AGG - CCE aggregation level BW - bandwidth

CCE - control channel element

CL - closed loop

CQI - channel quality indicator

CRC - cyclic redundancy check C-RNTI - cell radio network temporary identifier

DCI - downlink control information

DL - downlink

DRS - dedicated reference signal (also referred to as URS (UE-specific reference signal) ) eNB - evolved Node B, (also referred to as eNodeB)

LTE - Long Term Evolution

MIMO - multiple input multiple output

OL - open loop

PDCCH - physical downlink control channel PDSCH - physical downlink shared channel PMI - precoding matrix indicator

RA - resource allocation

RB - resource block

ReI - release

RI - rank indicator

RNTI - radio network temporary identifier

SNIR - signal to noise and interference ratio

TM - transmission mode

TM3 - transmission mode 3 (open-loop spatial multiplexing)

TM4 - transmission mode 4 (closed-loop spatial multiplexing)

TTI - transmission time interval

UE - user equipment

3GPP - 3rd Generation Partnership Project

Embodiments of the present invention relate to the Long Term Evolution (LTE) system currently specified in 3GPP, and, more specifically, to resource allocation, downlink (DL) control signalling and DL grant monitoring by the UE configured in open or closed loop spatial multiplexing or dual layer dedicated beamforming.

According to the LTE Rel-8 specification [c.f. 36.213 v8.4.0 or 8.5.0], UEs configured in the transmission modes (TM) closed/open-loop spatial multiplexing (OL SM (open-loop spatial multiplexing) with TM-3 (transmission mode 3) and CL SM (closed-loop spatial multiplexing) with TM-4 (transmission mode 4)) can be scheduled by the eNB downlink data on PDSCH by two types of downlink control signalling grants on PDCCH, namely DCI 2/2A and DCI IA. The key properties of these three types of DL grants are summarized in the following table 1. In LTE Rel-8 specification the open loop spatial multiplexing is equivalently termed as large delay CDD (cyclic delay diversity), as mentioned in 36.213 vδ.6.0, for example.

In the following table 1, it is listed in which transmission mode the UE is configured. Moreover, the payload size including CRC (cyclic redundancy check) for bandwidth (BW) is listed for each DCI format. Furthermore, supported PDSCH resource allocation types are listed, wherein there are three different types, namely types 0, 1 and 2. Type 2 can be further distinguished (by means of a bit flag) between localized virtual resource block (VRB) (LVRB) assignment and distributed VRB (DVRB) assignment. Furthermore, the supported physical downlink shared channel (PDSCH) precoding is listed.

Table 1: Comparison between DCI Format IA and 2/2A

As can be seen in table 1, the merit of using DCI IA in closed/open-loop spatial multiplexing is the reduced PDCCH size compared to single codeword transmission with DCI 2/2A. Message 2/2A has a factor 1.5 higher payload thus resulting in less coding gain for the same CCE aggregation level. This results in:

• Better DCI coverage of message IA compared to 2/2A ^ Coverage Gain, larger cell Size

• Lower aggregation level of message IA compared to 2/2A for the same SINR ^■* Capacity Gain on PDCCH and hence higher LTE system capacity

• Lower UE blocking on PDCCH for IA compared to 2/2A due to lower Aggregation and hence more potential CCE positions in the search space.

The estimates of coverage gains of DCI IA compared to DCI 2/2A are shown in table 2 assuming theoretical calculation of coding gain due to the message payload. There is a non negligible gain of typically ~ 1.5 dB for reasonable carrier bandwidths of 10 MHz or more.

Table 2 Theoretical coverage Gains of DCI Format IA over

DCI 2/2A

Link Level Simulations assuming real Channel Estimation show an even higher SINR gain of small vs. large DCI formats. Fig. 2A and 2B provide block error rate (BLER) vs. SINR curves for different CCE Aggregation Levels ranging from AGG-I to AGG-8. In particular, Fig. 2A shows 45 bit PDCCH BLER for EPA5 channel model assuming real channel estimation vs. SNIR, and Fig. 2B shows 60 bit PDCCH BLER for EPA5 channel model vs. SNIR.

Note that for higher Aggregation AGG-8 and AGG-4 the Gain is about 2 dB, however, for small AGG-I and AGG-2 there is a huge gain of roughly 3 - 4 dB .

However, as can also be seen in table 1, the two different DCI formats unfortunately have incompatible

PDSCH resource allocation capabilities, which results in scheduling restrictions and consequently throughput and capacity losses when considering the need of coexistence of these two resource allocation types especially in the same subframe. Namely, the resource allocation type 2, c.f. 36.213, supported with DCI format IA allocates only consecutive resource blocks either in the localized or distributed virtual block domain, while the resource allocation type 0 and 1 supported by DCI formats 2/2A allocate either resource block groups by a bitmap approach or allocate resource blocks (RBs) within a selected resource block group subset respectively.

A further issue, related to the current resource allocation setup with DCI 2/2A and IA in closed/open-loop spatial multiplexing relates to retransmissions: the channel quality indicator (CQI) reporting modes [c.f. 36.213] for closed/open-loop spatial multiplexing modes are tailored for transmission modes supported by corresponding DCI formats 2/2A. However, in case initial transmission or retransmission is carried out with the use of DCI IA, the resource allocation of this DCI does not fully match the available CQI information and reduces the gains of frequency domain packet scheduling. It has been agreed that in transmission modes 3 and 4, the eNode B can switch between DCI formats 2/2A and IA during a retransmission of a transport block. However, in this case, the problem that the CQI feedback and resource allocation mismatches for this transport block (TB) will be even more pronounced.

Another alternative for overcoming the drawbacks of the limited Rel-8 PDCCH signalling capabilities is semi- static adaptation of the transmission mode via dedicated RRC signalling. UEs under poor radio conditions, which are preferably supporting OL diversity or CL single codeword transmission, might be commanded transmission mode 2 for OL operation or transmission mode 6 for CL operation thus permanently using small DCI format Ix. Drawback of such a solution, however, is the slow transmission mode adaptation capability causing high signaling load on the air interface as well as high eNodeB internal processing load. Furthermore such a solution is much slower than the decisions provided by a dynamic MIMO mode switching algorithm. Also synchronizatin issues during the higher layer switching must be carefully handeled.

Summary of the Invention

Thus, it is an object of the present invention to overcome the shortcomings of the prior art. According to several embodiments of the present invention, a downlink control information format is monitored or created, wherein downlink control information format is a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

Alternatively, a downlink control information format is monitored or created, wherein the downlink control information format is a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

Further alternatively, a downlink control information format may be monitored or created, wherein the downlink control information format is a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

As an alternative, a downlink control information format may be monitored or created, wherein the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format .

As a further alternative, a dual code word downlink control information format may be monitored or created in a predetermined first search space, and a single stream downlink control information format may be monitored or created in a predetermined second search space.

Brief Description of the Drawings

These and other objects, features, details and advantages will become more fully apparent from the following detailed description of embodiments of the present invention which is to be taken in conjunction with the appended drawings, in which:

Fig. 1 a structure of an eNodeB and a user equipment (UE) according to some embodiments of the present invention;

Fig. 2A and 2B show SNIR gain for DCI format 1/lx over

DCI format 2/2A depending on CCE aggregation levels AGG-I to AGG- 8;

Fig. 3 shows system simulation results for a MIMO dual code word utilization vs. Load,

Fig. 4A and 4B show number of scheduled users per TTI versus PDCCH load for DCI format 1/lx and DCI format 2/2A at full load; and

Fig. 5 shows average aggregation levels for DCI format 1/lx and 2/2A at full load.

Detailed Description of embodiments

In the following, description will be made to embodiments of the present invention. It is to be understood, however, that the description is given by way of example only, and that the described embodiments are by no means to be understood as limiting the present invention thereto .

Fig. 1 shows structures of the network elements as used in some of the embodiments described in the following.

Reference number 11 shows an eNodeB as an example for a network control element or an apparatus creating downlink control information. The eNodeB 11 comprises a controller 111 which may perform the overall control of the eNodeB. The controller comprises a DCI generator 112 configured to create downlink control information, and a DCI positioner 113 configured to position or place the created DCI on a search space, e.g., a UE-specific search space or a common search space on a PDCCH. It is noted that the functions of the DCI generator 112 and the DCI positioner can be also carried out by the controller 111.

Reference number 12 shows an user equipment (UE) as an example for an apparatus monitoring downlink control information or downlink control information formats. The UE comprises a controller 121 which may perform the overall control of the UE. Furthermore, a monitor unit 122 is provided which is configured to monitor downlink control information formats on a PDCCH, for example. It is noted that the controller 121 and the monitor unit 122 may be provided as one unit, e.g., such that the controller performs the control and performs monitoring.

According to a first embodiment of the present invention, the monitor unit 122 of the UE 12 is configured in dual code word transmission mode (also referred to as dual or double stream transmission mode) to monitor a downlink control information format on a downlink control channel, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel. Similar, the controller 111 of the eNodeB is configured to create downlink control information in a dual code word transmission mode on a downlink control channel in a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel (e.g., PDSCH) .

Thus, according to examples of the first embodiment, it is proposed to add DCI Format 1 (as an example for the single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel) to the current DCI formats monitored by the UE in closed-loop and open- loop spatial multiplexing transmission modes (and in the future mode of DRS/URS-based dual layer beamforming) . The key features of DCI format 1, as specified in Rel-8, are listed in the following table 3.

DCI format 1 has similar size as DCI format IA (47 bit instead of 43 bit for 10 MHz Bandwidth) but relies on the same allocation types as DCI formats 2/2A.

Table 3 Properties of DCI format 1

for BW of {1.4,

3, 5, 10, 15,

20} MHz

Supported PDSCH Type 0 or Type resource 1 allocation types

Supported PDSCH OL Transmit precoding Diversity or CL single codeword transmission

As an alternative, another DCI format IX is added to the 3GPP standard having less payload than 2/2A and providing the same resource allocation type, preferably of the same size as the current DCI format 0 or IA in order not to increase the number of UE blind decodings .

According to a second embodiment of the present invention, the monitor unit 122 of the UE 12 is configured to monitor a downlink control information format, the downlink control information format being a dual code word (also referred to as dual stream) downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel (PDSCH) . Similar, the controller 111 of the eNodeB is configured to create downlink control information in a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel (PDSCH) .

That is, according to more concrete examples of the second embodiment, dual codeword DL grants (as examples for the downlink control information described above) are extended so that the resource allocation type(s) supported by these grants are compatible with the resource allocation of DCI IA (e.g. DCI 2X/2Y supporting resource allocation type 2 of LVRD and/or DVRB) .

Table 4 shows the sizes of the RB assignment fields for resource allocation type 0/1 and 2. As can be seen the sizes of RB assignment field for RA type 0/1 are always greater than the ones for RA type 2. Therefore, this embodiment can be implemented by inserting a RA Type 0/1 or 2 flag into the new dual code word DCI format (or some other indication e.g. base on CRC masking varying, redundancy version varying or scrambling varying) so that the flag/indication redefines the (or a subset of) RB assignment field to alternatively support RA type 2 (in addition to RA type 0/1)

Table 4 Size of RB Assignment Field for RA Type 0/1 and 2

BW [MHz] Size of RB Size of RB assignment field assignment field for RA Type 0/1 for RA Type 2 [bits] [bits]

1.4 6 5

3 8 7

5 13 9

10 17 11

15 19 12

20 25 13 The benefit of this approach is that the number of UE blind decoding trials is not increased compared to Rel-8.

According to a third embodiment of the present invention, the monitor unit 122 of the UE 12 is configured to monitor a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel (PDSCH) . Similar, the controller 111 of the eNodeB is configured to create downlink control information in a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel (PDSCH) . According to a first alternative of the third embodiment, the downlink control information format is adapted also to carry the payload of a single stream downlink control information format. According to a second alternative, appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

Thus, according to the third embodiment, the existing formats 2/2A are modified towards a message 2Z to carry the smaller payload of a format IX (or format 1) in case of diversity or single codeword transmission and appropriate coding is added to achieve a format 1/lX equivalent link performance and to achieve the same number of bits as the payload of format 2/2A, prior to convolutional encoding. That is, in case of the third embodiment, a number of bits remain unused. According to the first alternative of the third embodiment, the dual stream format is adapted such that only the payload of a single stream downlink allocation is contained; this basically results then in a single stream allocation format (e.g., a format Iz) . According to the other alternative of the third embodiment, as described above, the "unused" bits are used to add additional coding/improve the coding of the used bits thereby improving decoding performance in the UE.

According to a fourth embodiment the monitor unit 122 of the UE 12 is configured to monitor a dual code word downlink control information format in a first search space, and to monitor a single stream downlink control information format in a predetermined second search space. Similar, the controller 111 of the eNodeB 11 is configured to position downlink control information in a dual code word downlink control information format in a first search space, and to position downlink control information in a single stream downlink control information in a predetermined second search space.

That is, according to examples of the fourth embodiment, it is introduced the option of expanding (or appending) the PDCCH search space for the cases where more DCI formats for DL allocations are introduced.

It is noted that the above-described embodiments and its examples can be implemented separately, but can also be arbitrarily combined. For example, the new formats for the downlink control information as specified in the first, second and third embodiments and its examples can be used in connection with the expanded search space as defined in the third embodiment and its example.

In the following, examples of the above-described embodiments and their effects are described in more detail .

In particular, in the following it is described how the embodiments can be implemented. Namely:

• Adding DCI format 1 (or new IX) to the formats monitored by the UE (in TM3, TM4, or in other dual code word mode) only in UE-specific search spaces, the DCI CRC should be scrambled with a cell radio network temporary identifier (C-RNTI), or

• Adding format 1 (or new IX) to the formats monitored by the UE (in TM3, TM4, or in other dual code word mode) both in UE-specific search spaces and the common search spaces, the DCI CRC should be scrambled with the cell radio network temporary identifier (C-RNTI), or

• Modifying format 2 (or new 2X) including sufficient additional coding to achieve a format IX (or format 1) equivalent link performance for OL diversity or CL single codeword transmission in tramsmission modes TM- 3, TM-4 or in dual layer DRS-based beamforming, as a more concrete example of the third embodiment described above. More specifically, this can be achieved by appropriate coding of the DCI lX/1 payload (e.g. repetition coding) prior or after the CRC attachment but prior to convolutional encoding so that the size of the DCI 2/2A and DCI IX (or DCI 1) is the same (prior to convolutional encoding) . According to the last alternative method, an additional indication could be used to allow the UE to distinguish the two DCI formats. In this case e.g. a flag to distinguish the DCI format 2/2A from IX/ 1 can be added to the payload of both DCI formats or indicative CRC masking can be used The benefit of this approach is that the number of UE blind decoding trials is not increased.

As an option for the case that single stream OL Diversity or CL single codeword transmission and dual code word OL SM or CL double codeword transmission are both used, the eNB could use the new format for DL transmission grants, if single stream OL Diversity or CL single codeword transmission has been decided, for example by the fast dynamic MIMO switch. For dual code word OL SM or CL double codeword transmission, the existing formats 2/2A could be used.

The proposal will require a moderate increase of the UE PDCCH blind decoding trials from the current 44 to 76 blind decodes per subframe (the increase would be applicable to UEs in TM3, TM4, or in other dual code word beamforming mode) . However, the current number of blind decoding attempts is not considered extensive and the required increase is seen as feasible in the Rel-9 timeframe .

Alternatively, if a new DCI format with the properties as described in connection with the first embodiment, but with the payload size equal to the size of DCI lA/0 is specified, then there would be no increase in the number of UE blind decoding trials compared to Rel-8.

One option, as described above in more general in connection with the third embodiment, would be to introduce an expansion of the UE-specific search space (but could also be generalized to the common search space) . For example, it is assumed that a UE is configured to be monitoring DCI format 2/2A using the UE specific search space given by 3GPP 36.213, section 9.1.1. In order to allow for fast switching to DCI format 1 (or whichever single-stream DCI format is configured) , the UE is given an additional search space to look for the PDCCH. This additional search space could be defined as a subset of the normal PDCCH search space, but could also be defined as an expansion/extension of the traditional search space. On option for this would be to introduce a simple and linear extension of the search space. That is, if the UE is searching CCEs (control channel elements) 1-6 using the regular UE-specific search space (looking for DCI format 2/2A) , it would be searching CCEs 7-9 for DCI format 1 (as a simple example) . The benefits of using this approach are as follows :

• The eNB is provided an option for fast switching between single and dual code word transmission.

• The UE search space is expanded by a small fraction.

• The PDCCH blocking would be reduced, as the eNB will have more positions' to place the scheduled UEs upon

(and chose to downgrade the link performance in case of switching to single-stream) .

• The proposed solution is backwards compatible, i.e. the existing algorithms in the eNB for PDCCH scheduling need only minor upgrade since the proposed solution fully contains the existing Rel-8 compatible one.

Alternatively, it is also possible to apply an opposite configuration (with a single-stream UE using DCI format 1) where DCI format 2/2A is used to create the expanded search space. That is, this basically refers to a UE being configured in TM 2.

In more detail, using the fourth embodiment and this alternative thereof, it is possible to implicitly change between single and dual codeword transmission modes without the explicit need for RRC reconfiguration while always being able to use the most appropriate DCI format provided that according feedback information (RI/PMI/CQI) is available.

Note that the simple example above could also be refined such that e.g. a certain range of the search space is valid for both DCI formats, e.g. there might be some overlap such as CCEs 1-4 for DCI format 2/2A, 5-7 for DCI 1 and 2/2A as well as CCEs 8-9 for DCI format 1.

Instead of a simple and linear extension also a more complex extension by means of other starting points given by a Hashing function is feasible.

The following advantages are obtained by examples of the embodiments described above:

• The same resource allocation types can be supported by the single codeword and dual codeword DL scheduling grants used in closed/open-loop spatial multiplexing modes (or in other modes like DRS-based dual layer beamforming) thus: o Efficient coexistence of resource allocations scheduled with dual codeword DL grants (DCI 2/2A) and with single codeword DL grants (DCI 1) is enabled allowing to avoid scheduler restrictions (due to mismatch between the DCI IA and 2/2A resource allocation types) . o A better match between the available CQI feedback and the resource allocation types is provided allowing higher gains of the frequency domain scheduling of the corresponding PDSCH. PDCCH coverage gains of in case a single TB is scheduled with DCI 1 not 2/2A as estimated in the following table 5.

PDCCH capacity gain: the link level gains can be also translated into less PDCCH resources needed for single code word transmission and thus a higher overall PDCCH capacity.

Lower Aggregation levels for the same SNIR results is less PDCCH blocking, since the average Aggregation level is significantly decreased. Moreover, the small Aggregation levels allow for more search positions on the PDCCH search spaces (AGG-I and AGG-2 have 6 positions whereas AGG-4 and AGG-8 have only 2 positions) .

Furthermore, retransmissions of a single codeword also could use the more appropriate single codeword DCI format.

Table 5 Theoretical coverage Gains of DCI Format 1 over

DCI 2/2A

It is noted that DCI 1 can even outperform IA in 1.4 MHz and in configurations where UL BW is grater than the DL BW due to IA padding.

Note that in a fully loaded LTE system, the portion of OL/CL dual code word utilization is well below 20%. Single stream diversity modes are dominant. Hence the usage of DCI format 2/2A is a pure waste of PDCCH capacity. With DCI format 1/lX, a significantly higher number of users can be served with less blocking. The same would be valid for a modified DCI format 2/2X with equivalent format 1/lX link performance.

Fig. 3 shows simulation results for the MIMO dual code word utilization vs. Load, and in more detail OL and CL MIMO spatial multiplexing Utilization vs. System Load given in avg. #UEs per cell.

Figs. 4A and 4B shows the number of users possible for scheduling per transmission time interval (TTI) versus PDCCH load when limiting to -4% blocking, and in more detail the number of scheduled Users per TTI for the different DCI formats (Fig. 4A:DCI format 1/1X, Fig. 4B: DCI format 2) vs. PDCCH Loading (fully loaded 10 MHz System) . The obtained capacity gain is significant and is in the order of up to 50% for the same PDCCH Load (practically, it can be expected up to 20-30%) . In Figs. 4A and 4B, the parameter "alpha" is indicated on the abscissa as an indicator of the PDCCH load, and is an eNodeB internal parameter. In more detail, alpha represents the load, i.e. alpha = 1 is fully loaded, alpha > 1 means over-provisioning and alpha < 1 means fractionally loaded. Mapping the Link Level from Fig. 2 on a CELL SNIR CDF obtained by system level simulations at full Load. Fig. 5, which illustrates Average Aggregation Levels for DCI format 1 and 2/2A at full Load shows, that the average Aggregation Levels for DCI format 2/2A are significantly higher than for format 1. Note that AGG-4 has only 2 search positions on PDCCH, whereas AGG-2 has 6 positions.

It is furthermore noted that the names of the new DCI format are not limited to IX, 2X, 2Y, 2Z etc., but can be modified as necessary. For example, the format 2Z according to the third embodiment could be named as 2C, 2D or the like.

In the following, several embodiments of the invention are described in generic terms by referring to several aspects thereof.

According to a first aspect of several embodiments of the invention, an apparatus is provided which comprises a monitor unit configured in dual code word transmission mode to monitor a downlink control information format on a downlink control channel, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

The downlink control information format may be a downlink control information format 1 or IX.

According to a second aspect of embodiments of the present invention, an apparatus is provided which comprises a monitor unit configured to monitor a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The downlink control information may comprise a dual codeword downlink grant.

According to a third aspect of embodiments of the present invention, an apparatus is provided which comprises a monitor unit configured to monitor a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

According to an alternative of the third aspect, an apparatus is provided which comprises a monitor unit configured to monitor a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

The first to third aspects may be modified as follows: The downlink control information format may comprise a cyclic redundancy check scrambled with a cell radio network temporary identifier.

The monitor may be configured to monitor user equipment specific search spaces only.

The monitor may be configured to monitor user equipment specific search spaces and common search spaces.

According to a fourth aspect of embodiments of the present invention, an apparatus is provided which comprises a monitor unit configured to monitor a dual code word downlink control information format in a predetermined first search space, and to monitor a single stream downlink control information format in a predetermined second search space.

The fourth aspect may be modified as follows:

The second search space may be an extension of the first search space or a subset of the first search space, or the first search space may be a subset of the second search space.

The first search space may be a user equipment specific search space or a common search space, or a combination thereof .

The first search space and the second search space may partly overlap each other.

The single stream downlink control information format may be a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

The dual code word downlink control information format may be a format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The dual code word downlink control information format may be a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel.

The apparatus according to the first to fourth aspects may be or may be part of a user equipment.

According to a fifth aspect of embodiments of the present invention, an apparatus is provided which comprises a controller configured to create downlink control information in dual code word transmission mode on a downlink control channel using a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

The fifth aspect may be modified as follows:

The controller may be configured to use, for a single stream open loop diversity, the single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel. The controller may be configured to use, for a open-loop double codeword transmission or closed-loop double codeword transmission, a dual code word downlink control information format for a physical downlink shared channel .

According to a sixth aspect of embodiments of the present invention, an apparatus is provided which comprises a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The sixth aspect may be modified as follows:

The downlink control information may comprise a dual codeword downlink grant.

The controller may be configured to use, for open loop dual codeword transmission or closed loop dual codeword transmission or DRS-based dual layer/codeword transmission, the dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The controller may be configured to use, for a single stream open loop diversity, a single stream downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

According to a seventh aspect of embodiments of the present invention, an apparatus is provided which comprises a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

According to an alternative of the seventh aspect an apparatus is provided which comprises a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

The fifth to seventh aspects may be modified as follows:

The downlink control information may comprise a cyclic redundancy check scrambled with a cell radio network temporary identifier.

The controller may be configured to position the downlink control information in user equipment specific search spaces only.

The controller may be configured to position the downlink control information in user equipment specific search spaces and common search spaces. According to a eighth aspect of embodiments of the present invention, an apparatus is provided which comprises a controller configured to position downlink control information in a dual code word downlink control information format in a predetermined first search space, and to position downlink control information in a single stream downlink control information in a predetermined second search space.

The eighth aspect may be modified as follows:

The first search space may be a user equipment specific search space or a common search space, or a combination thereof.

The apparatus according to the fifth to eighth aspects may be or may be part of a network control element.

The network control element may be an eNodeB.

According to a ninth aspect of several embodiments of the invention, an apparatus is provided which comprises means for monitoring monitor a downlink control information format on a downlink control channel in dual code word transmission mode, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

According to a tenth aspect of embodiments of the present invention, an apparatus is provided which comprises means for monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

The downlink control information may comprise a dual codeword downlink grant.

According to an eleventh aspect of embodiments of the present invention, an apparatus is provided which comprises means for monitoring a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

According to an alternative of the eleventh aspect, an apparatus is provided which comprises means for monitoring a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format .

The ninth to eleventh aspects may be modified as follows:

The downlink control information format may comprise a cyclic redundancy check scrambled with a cell radio network temporary identifier.

The apparatus may comprise means monitoring a user equipment specific search spaces only.

The apparatus may comprise means for monitoring user equipment specific search spaces and common search spaces .

According to a twelfth aspect of embodiments of the present invention, an apparatus is provided which comprises means for monitoring a dual code word downlink control information format in a predetermined first search space, and for monitoring a single stream downlink control information format in a predetermined second search space.

The twelfth aspect may be modified as follows:

The dual code word downlink control information format may be a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel. The apparatus according to the ninth to twelfth aspects may be or may be part of a user equipment.

According to a thirteenth aspect of embodiments of the present invention, an apparatus is provided which comprises means for creating downlink control information in dual code word transmission mode on a downlink control channel using a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

The thirtheenth aspect may be modified as follows:

The apparatus may comprise means for using, for a single stream open loop diversity, the single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

The apparatus may comprise means for using, for a open- loop double codeword transmission or closed-loop double codeword transmission, a dual code word downlink control information format for a physical downlink shared channel .

According to a fourteenth aspect of embodiments of the present invention, an apparatus is provided which comprises means for creating downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

The fourteenth aspect may be modified as follows:

The downlink control information may comprise a dual codeword downlink grant.

The apparatus may comprise means for using, for open loop dual codeword transmission or closed loop dual codeword transmission or DRS-based dual layer/codeword transmission, the dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The apparatus may comprise means for using, for a single stream open loop diversity, a single stream downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

According to a fifteenth aspect of embodiments of the present invention, an apparatus is provided which comprises means for creating downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

According to an alternative of the seventh aspect an apparatus is provided which comprises means for creating downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

The thirteenth to fifteenth aspects may be modified as follows :

The apparatus may comprise means for positioning the downlink control information in user equipment specific search spaces only.

The apparatus may comprise means for positioning the downlink control information in user equipment specific search spaces and common search spaces.

According to a sixteenth aspect of embodiments of the present invention, an apparatus is provided which comprises means for positioning downlink control information in a dual code word downlink control information format in a predetermined first search space, and means for positioning downlink control information in a single stream downlink control information in a predetermined second search space.

The sixteenth aspect may be modified as follows: The second search space may be an extension of the first search space or a subset of the first search space, or the first search space may be a subset of the second search space.

The apparatus according to the thirteenth to sixteenth aspects may be or may be part of a network control element .

The network control element may be an eNodeB.

According to a seventeenth aspect of several embodiments of the present invention, a method is provided which comprises monitoring a downlink control information format in a dual code word transmission mode on a downlink control channel, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

According to an eighteenth aspect of several embodiments of the present invention, a method is provided which comprises monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The downlink control information may comprise a dual codeword downlink grant.

According to a nineteenth aspect of several embodiments of the present invention, a method is provided which comprises monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format .

According to an alternative of the nineteenth aspect a method is provided which comprises monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

The seventeenth to nineteenth aspects may be modified as follows :

The monitoring may monitor user equipment specific search spaces only.

The monitoring may monitor user equipment specific search spaces and common search spaces.

According to a twentieth aspect of several embodiments of the present invention, a method is provided which comprises monitoring a dual code word downlink control information format in a predetermined first search space, and monitoring a single stream downlink control information format in a predetermined second search space .

The twentieth aspect may be modified as follows:

The method is carried out by an apparatus such as a user equipment or a part thereof.

According to a twenty-first aspect of several embodiments of the present invention, a method is provided which comprises creating downlink control information in a dual code word transmission mode on a downlink control channel using a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel. The twenty-first aspect may be modified as follows:

The downlink control information format may be a downlink control information format 1.

The method may further comprise using, for a single stream open loop diversity, the single stream downlink control information format being adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

The method may further comprise using, for a dual code word open loop diversity or closed-loop double codeword transmission, a dual code word downlink control information format resource allocation type for a physical downlink shared channel.

According to a twenty-second aspect of several embodiments of the present invention, a method is provided which comprises creating downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The twenty-second aspect may be modified as follows:

The downlink control information may comprise a dual codeword downlink grant.

The method may further comprise using, for open loop dual codeword transmission or closed loop dual codeword transmission or DRS-based dual layer/codeword transmission, the dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

The method may further comprise using, for a single stream open loop diversity, a single stream downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

According to a twenty-third aspect of several embodiments of the present invention, a method is provided which comprises creating downlink control information in a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel, and to carry the payload of a single stream downlink control information format.

According to an alternative of the twenty-second aspect a method is provided which comprises creating downlink control information in a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel, and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

The twenty-first to twenty-third aspects may be modified as follows: The downlink control information may comprise a cyclic redundancy check scrambled with a cell radio network temporary identifier.

The method may further comprise positioning the downlink control information in user equipment specific search spaces only.

The method may further comprise positioning the downlink control information in user equipment specific search spaces and common search spaces.

According to a twenty-fourth aspect of several embodiments of the present invention, a method is provided which comprises positioning downlink control information in a dual code word downlink control information format in a predetermined first search space, and positioning downlink control information in a single stream downlink control information in a predetermined second search space.

The twenty-fourth aspect may be modified as follows:

The first search space and the second search space may partly overlap each other. The single stream downlink control information format may be a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

The method is carried out by an apparatus such as a network control element or a part thereof.

The network control element may be an eNodeB.

According to a tenth aspect of several embodiments of the present invention, a computer program product is provided which comprises code means for performing a method according any of the above seventeenth to twenty-fourth aspects or their modifications when run on a processing means or module.

It is to be understood that any of the above modifications can be applied singly or in combination to the respective aspects and/or embodiments to which they refer, unless they are explicitly stated as excluding alternatives .

For the purpose of the present invention as described herein above, it should be noted that - method steps likely to be implemented as software code portions and being run using a processor at a network element or terminal (as examples of devices, apparatuses and/or modules thereof, or as examples of entities including apparatuses and/or modules therefore) , are software code independent and can be specified using any known or future developed programming language as long as the functionality defined by the method steps is preserved; - generally, any method step is suitable to be implemented as software or by hardware without changing the idea of the invention in terms of the functionality implemented; - method steps and/or devices, units or means likely to be implemented as hardware components at the above- defined apparatuses, or any module (s) thereof, (e.g., devices carrying out the functions of the apparatuses according to the embodiments as described above, UE, eNodeB etc. as described above) are hardware 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; - devices, units or means (e.g. the above-defined apparatuses, or any one of their respective means) can be implemented as individual devices, units or means, but this does not exclude that they are implemented in a distributed fashion throughout the system, as long as the functionality of the device, unit or means is preserved; - an 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 an 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 an apparatus or as an assembly of more than one apparatus, whether functionally in cooperation with each other or functionally independently of each other but in a same device housing, for example.

It is noted that the embodiments and examples described above are provided for illustrative purposes only and are in no way intended that the present invention is restricted thereto. Rather, it is the intention that all variations and modifications be included which fall within the spirit and scope of the appended claims.

Claims

1. An apparatus comprising a monitor unit configured in dual code word transmission mode to monitor a downlink control information format on a downlink control channel, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

2. The apparatus according to claim 1, wherein the downlink control information format is a downlink control information format 1 or IX.

3. An apparatus comprising a monitor unit configured to monitor a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

4. The apparatus according to claim 3, wherein the downlink control information comprises a dual codeword downlink grant.

5. An apparatus comprising a monitor unit configured to monitor a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

6. An apparatus comprising a monitor unit configured to monitor a downlink control information format, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format .

7. The apparatus according to one of the claims 1 to 6, wherein the downlink control information format comprises a cyclic redundancy check scrambled with a cell radio network temporary identifier.

8. The apparatus according to one of the claims 1 to 6, wherein the monitor is configured to monitor user equipment specific search spaces only.

9. The apparatus according to one of the claims 1 to 6, wherein the monitor is configured to monitor user equipment specific search spaces and common search spaces.

10. An apparatus comprising a monitor unit configured to monitor a dual code word downlink control information format in a predetermined first search space, and to monitor a single stream downlink control information format in a predetermined second search space .

11. The apparatus according to claim 10, wherein the second search space is an extension of the first search space or a subset of the first search space, or the first search space is a subset of the second search space.

12. The apparatus according to claim 10 or 11, wherein the first search space is a user equipment specific search space or a common search space, or a combination thereof .

13. The apparatus according to one of the claims 10 to

12, wherein the first search space and the second search space partly overlap each other.

14. The apparatus according to one of the claims 10 to

13, wherein the single stream downlink control information format is a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

15. The apparatus according to one of the claims 10 to 13, wherein the dual code word downlink control information format is a format adapted to support a type

2 resource allocation type for a physical downlink shared channel.

16. The apparatus according to one of the claims 10 to 13, wherein the dual code word downlink control information format is a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel.

17. The apparatus according to one of the claims 1 to 16, wherein the apparatus is or is part of a user equipment.

18. An apparatus comprising a controller configured to create downlink control information in dual code word transmission mode on a downlink control channel using a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

19. The apparatus according to claim 18, wherein the downlink control information format is a downlink control information format 1.

20. The apparatus according to claim 18 or 19, wherein the controller is configured to use, for a single stream open loop diversity, the single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

21. The apparatus according to claim 20, wherein the controller is configured to use, for an open-loop double codeword transmission or closed-loop double codeword transmission, a dual code word downlink control information format for a physical downlink shared channel .

22. An apparatus comprising a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

23. The apparatus according to claim 22, wherein the downlink control information comprises a dual codeword downlink grant.

24. The apparatus according to claim 22 or 23, wherein the controller is configured to use, for open loop dual codeword transmission or closed loop dual codeword transmission or DRS-based dual layer/codeword transmission, the dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

25. The apparatus according to claim 24, wherein the controller is configured to use, for a single stream open loop diversity, a single stream downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

26. An apparatus comprising a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

27. An apparatus comprising a controller configured to create downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

28. The apparatus according to one of the claims 18 to 27, wherein the downlink control information comprises a cyclic redundancy check scrambled with a cell radio network temporary identifier.

29. The apparatus according to one of the claims 18 to 27, wherein the controller is configured to position the downlink control information in user equipment specific search spaces only.

30. The apparatus according to one of the claims 18 to 27, wherein the controller is configured to position the downlink control information in user equipment specific search spaces and common search spaces.

31. An apparatus comprising a controller configured to position downlink control information in a dual code word downlink control information format in a predetermined first search space, and to position downlink control information in a single stream downlink control information in a predetermined second search space.

32. The apparatus according to claim 31, wherein the second search space is an extension of the first search space or a subset of the first search space, or the first search space is a subset of the second search space.

33. The apparatus according to claim 31 or 32, wherein the first search space is a user equipment specific search space or a common search space, or a combination thereof .

34. The apparatus according to one of the claims 31 to 33, wherein first search space and the second search space partly overlap each other.

35. The apparatus according to one of the claims 31 to 34, wherein the single stream downlink control information format is a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

36. The apparatus according to one of the claims 31 to 34, wherein the dual code word downlink control information format is a format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

37. The apparatus according to one of the claims 31 to 34, wherein the dual code word downlink control information format is a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel.

38. The apparatus according to one of the claims 18 to

37. wherein the apparatus is or is part of a network control element.

39. The apparatus according to claim 38, wherein the network control element is an eNodeB.

40. A method comprising monitoring a downlink control information format in a dual code word transmission mode on a downlink control channel, the downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

41. The method according to claim 40, wherein the downlink control information format is a downlink control information format 1 or IX.

42. A method comprising monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

43. The method according to claim 42, wherein the downlink control information comprises a dual codeword downlink grant.

44. A method comprising monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and to carry the payload of a single stream downlink control information format.

45. A method comprising monitoring a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel and and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

46. The method according to one of the claims 40 to 45, wherein the downlink control information format comprises a cyclic redundancy check scrambled with a cell radio network temporary identifier.

47. The method according to one of the claims 40 to 46, wherein the monitoring is configured to monitor user equipment specific search spaces only.

48. The method according to one of the claims 40 to 46, wherein the monitoring is configured to monitor user equipment specific search spaces and common search spaces .

49. A method comprising monitoring a dual code word downlink control information format in a predetermined first search space, and monitoring a single stream downlink control information format in a predetermined second search space .

50. The method according to claim 49, wherein the second search space is an extension of the first search space or a subset of the first search space, or the first search space is a subset of the second search space.

51. The method according to claim 49 or 50, wherein the first search space is a user equipment specific search space or a common search space, or a combination thereof.

52. The method according to one of the claims 49 to 51, wherein the first search space and the second search space partly overlap each other.

53. The method according to one of the claims 49 to 52, wherein the single stream downlink control information format is a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

54. The method according to one of the claims 49 to 52, wherein the dual code word downlink control information format is a format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

55. The method apparatus according to one of the claims 49 to 52, wherein the dual code word downlink control information format is a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel.

56. The method according to one of the claims 40 to 56, wherein the method is carried out by a user equipment or a part thereof.

57. A method comprising creating downlink control information in a dual code word transmission mode on a downlink control channel using a downlink control information format being a single stream downlink control information format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

58. The method according to claim 57, wherein the downlink control information format is a downlink control information format 1.

59. The method according to claim 57 or 58, further comprising using, for a single stream open loop diversity, the single stream downlink control information format being adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel.

60. The method according to claim 59, further comprising using, for a dual code word open loop diversity or closed-loop double codeword transmission, a dual code word downlink control information format resource allocation type for a physical downlink shared channel.

61. A method comprising creating downlink control information on a downlink control channel using a downlink control information format being a dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

62. The method according to claim 61, wherein the downlink control information comprises a dual codeword downlink grant.

63. The method according to claim 61 or 62, further comprising using, for open loop dual codeword transmission or closed loop dual codeword transmission or DRS-based dual layer/codeword transmission, the dual code word downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel .

64. The method according to claim 63, further comprising using, for a single stream open loop diversity, a single stream downlink control information format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

65. A method comprising creating downlink control information in a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel, and to carry the payload of a single stream downlink control information format.

66. A method comprising creating downlink control information in a downlink control information format on a downlink control channel, the downlink control information format being a dual code word downlink control information format adapted to support a single stream type 0 or type 1 resource allocation type for a physical downlink shared channel, and wherein appropriate coding is added to achieve the same number of bits as the payload of a dual stream downlink control information format.

67. The method according to one of the claims 57 to 66, wherein the downlink control information comprises a cyclic redundancy check scrambled with a cell radio network temporary identifier.

68. The method according to one of the claims 57 to 67, further comprising positioning the downlink control information in user equipment specific search spaces only.

69. The method according to one of the claims 57 to 67, further comprising positioning the downlink control information in user equipment specific search spaces and common search spaces .

70. A method comprising positioning downlink control information in a dual code word downlink control information format in a predetermined first search space, and positioning downlink control information in a single stream downlink control information in a predetermined second search space.

71. The method according to claim 70, wherein the second search space is an extension of the first search space or a subset of the first search space, or the first search space is a subset of the second search space.

72. The method according to claim 70 or 71, wherein the first search space is a user equipment specific search space or a common search space, or a combination thereof.

73. The method according to one of the claims 70 to 72, wherein first search space and the second search space partly overlap each other.

74. The method according to one of the claims 70 to 73, wherein single stream downlink control information format is a format adapted to support a type 0 or type 1 resource allocation type for a physical downlink shared channel .

75. The method according to one of the claims 70 to 73, wherein dual code word downlink control information format is a format adapted to support a type 2 resource allocation type for a physical downlink shared channel.

76. The method according to one of the claims 70 to 73, wherein dual code word downlink control information format is a format adapted to support a single stream type 1 or 0 resource allocation type for a physical downlink shared channel.

77. The method according to one of the claims 40 to 76, wherein the method is carried out by a network control element or a part thereof.

78. The method according to claim 77, wherein the network control element is an eNodeB.

79. A computer program product comprising code means for performing a method according to any one of claims 40 to 78 when run on a processing means or module.