WO2013117014A1

WO2013117014A1 - Identifying a subset of a plurality of radio resources of a downlink control channel

Info

Publication number: WO2013117014A1
Application number: PCT/CN2012/071041
Authority: WO
Inventors: Li Zhang; Peter Skov; Frank Frederiksen; Chunye Wang
Original assignee: Nokia Siemens Networks Oy
Priority date: 2012-02-10
Filing date: 2012-02-10
Publication date: 2013-08-15

Abstract

It is described a method for identifying a subset of a plurality of radio resources of a downlink control channel, wherein the subset of radio resources is temporarily allocated to a downlink shared channel, wherein the downlink control channel is used for sending downlink control information being responsive for controlling a transmission between a user equipment and a base station via a radio transmission channel, wherein the downlink shared channel is used for sending common user data and control signals to the user equipment, wherein a plurality of radio resources of th radio transmission channel is allocated to the downlink control channel, and wherein a subset of the plurality of radio resources of the downlink control channel is temporarily allocated to the downlink shared channel. The method comprises receiving, by the user equipment, information being indicative for the subset of radio resources of the plurality of radio resources of the downlin control channel, which are temporarily allocated to the downlink shared channel, if they are unused by the downlink control channel, wherein the information is provided via at least one of the plurality of radio resources of the downlin control channel, and identifying, by the user equipment, the subset of the plurality of radio resources of the downlink control channel based on the received information, which subset is temporarily allocated to the downlink control channel.

Description

IDENTIFYING A SUBSET OF A PLURALITY OF RADIO RESOURCES OF A DOWNLINK CONTROL CHANNEL

Field of invention

The present invention relates to the field of cellular networks, especially to LTE networks, and in particular to the field of enhanced downlink control channel signalling.

Art Background In the latest LTE rel. 11+ discussion, it has been agreed that within the frequency domain, there will be an enhanced physical downlink control channel region, which will contain all physical resource blocks (PRB) . In particular, there have been some agreements on ePDCCH-PDSCH (enhanced physical downlink control channel/ physical downlink shared channel) multiplexing .

According to the discussion, there may be some PRB-pair-level multiplexing between PDSCHs and ePDCCHs within a subframe using FDM (frequency division multiplexing) . A PRB pair may contain parts of different ePDCCHs to different UEs . There is the assumption that there is no multiplexing of PDSCH and ePDCCH within a PRB pair. However, if there is any

multiplexing of PDSCH and ePDCCH within a PRB pair, it would be by FDM.

According to the discussion, there will be an ePDCCH region defined in frequency domain comprising all the PRBs on which an ePDCCH is transmitted. However, if there are any empty PRBs in the ePDCCH region which cannot be utilized for data transmission, this would result in a waste of resources if some of the empty PRBs in the ePDCCH region. If a base station or NB would re-use empty resources in the ePDCCH region for PDSCH, there may still be a problem how to inform a user equipment about this re-use.

There may be a need for an improved system and method for informing a user equipment about resources in the ePDCCH region being used for PDSCH.

Summary of the Invention

This need may be met by the subject matter according to the independent claims. Advantageous embodiments of the present invention are described by the dependent claims.

According to a first aspect of the invention there is provided a method for identifying a subset of a plurality of radio resources of a downlink control channel. The subset of radio resources may be temporarily allocated to a downlink shared channel. The downlink control channel is used for sending downlink control information being responsive for controlling a transmission between a user equipment and a base station via a radio transmission channel. The downlink shared channel is used for sending common user data and control signals to the user equipment. A plurality of radio resources of the radio transmission channel is allocated to the downlink control channel, and a subset of the plurality of radio resources of the downlink control channel is temporarily allocated to the downlink shared channel. The method comprises receiving, by the user equipment,

information being indicative for the subset of radio

resources of the plurality of radio resources of the downlink control channel, which are temporarily allocated to the downlink shared channel, if they are unused by the downlink control channel, wherein the information is provided via at least one of the plurality of radio resources of the downlink control channel, and identifying, by the user equipment, the subset of the plurality of radio resources of the downlink control channel based on the received information, which subset is temporarily allocated to the downlink control channel .

This aspect of the invention is based on the idea that a user equipment may be informed via resources of the downlink control channel whether some resources are temporarily allocated to the downlink shared channel or not. According to the described method, dynamical re-use of some empty ePDCCH PRBs for PDSCH may be enabled, without introducing any common control channel to indicate the ePDCCH region usage or utilization.

The described method relates in particular to LTE rel. 11+ and in particular to enhanced downlink (DL) control channel signalling, but is not limited to these environments. The described method provides a way to enhance the re-use of empty resources of the downlink control channel (ePDCCH, enhanced physical downlink control channel) by the downlink shared channel (PDSCH, physical downlink shared channel) .

According to the latest discussions in view of LTE Rel.11+ , it may be expected that there will be an ePDCCH region defined in frequency domain comprising all the physical resource blocks (PRBs) on which ePDCCH is transmitted. It would be a waste of resources if some of the empty PRBs in the ePDCCH region (for example when there are few users allocated with large bandwidth) cannot be utilized for data transmission .

The frequency resource allocation on PDSCH might not be flexible enough to be in PRB-granularity, and it is very likely that the granularity for ePDCCH allocation {1- or 2- PRB) will be smaller than that of PDSCH (4-PRB for example) . One approach could be to have a pre-defined rule that marks all pre-assigned ePDCCH resources as already reserved for control transmission and the user equipment (UE) , whose frequency allocation would include such ePDCCH PRBs, will by default assume these resources to be punctured out from its PDSCH. Then in one UE' s frequency allocation, there could be some ePDCCH PRBs, which are left empty without any control transmission, and theses resources should be dynamically reused for PDSCH. The problem to dynamically re-use those empty ePDCCH PRB for PDSCH is to ensure the UE has the information about the usage of those PRBs, so that eNB and UE can have a common understanding about the TB size, the amount of

physical resource, and following this, how the data on PDSCH is rate matched.

One approach could be that the UE blind decodes what is transmitted in the ePDCCH PRB. Since DMRS (demodulation reference signal) sequence on the PRBs of the ePDCCH will usually be different depending on what is transmitted, the UE can try to decode whether the PRB is used for control

transmission. This method may complicate UE decoding behavior, and more importantly, it may require that the UE has an extra knowledge on what is the DMRS sequence if the ePDCCH PRB is used for control {such as id or group id of other UEs) .

Further, there may be a risk that the UE erroneously detects the existence/non-existence of control information and

creates a wrong puncturing pattern, and would hence create erroneous detection of the data packet (s).

A further approach could be a cell-specific Ll indication. This method may introduce a PCFICH (physical control format indicator channel) type of control channel for ePDCCH region, which means the ePDCCH region can be different from subframe to subframe. The problem with this method may be that a new common control channel is introduced, and some semi-static resources should be reserved for this channel (typically in distributed manner) , which would potentially be overlapping with and restricting Rel'8, Rel' 9, and Rel'lO (or other earlier releases) PDSCH scheduling options. The idea of the herein described method is to provide a method with which it may be ensured that the user equipment is informed or has knowledge about a re-scheduling of

resources of the ePDCCH to the PDSCH and to ensure at the same time that other Rel. 10 channels (like PDSCH) or

channels of any other earlier releases may be still supported.

According to the described method, dynamic re-use of empty ePDCCH PRBs to PDSCH may be enabled. Specifically, the UE may be informed about the usage of ePDCCH PRBs, for instance through DCI (downlink control information) . It should be noted that this indication only relates to PDSCH puncturing in the PRBs where the UE is scheduled, and has no impact on the UE assumption on what is transmitted on ePDCCH PRBs outside the UE's frequency allocation. It should be further noted that it is assumed that the ePDCCH region is semi- statically determined or configured (it can be different from subframe to subframe but in a pre-defined pattern) .

Based on received information, the UE may determine a subset of resources of the ePDCCH being re-scheduled for the PDSCH. This may be the case for instance if some of the resources of the ePDCCH would be empty. The UE may then identify these resources and may take this into account when monitoring the transmissions .

The term "user equipment" in this context may be any type of communication end device, which is capable of performing the described determinations and identifications. The UE may be in particular a cellular mobile phone, a Personal Digital Assistant (PDA) , a notebook computer, a printer and/or any other movable communication device.

The term "base station" in this context may denote any kind of physical entity being able to hold one or more cells. A base station in this context may be any kind of network device providing the functionality of re-scheduling or temporarily allocating resources of the ePDCCH to the PDSCH. The base station may be for example an eNodeB or eNB.

The "downlink control channel" may be physical downlink control channel (PDCCH) and in particular an enhanced PDCCH (ePDCCH) as introduced by LTE Rel. 11+. Such a channel is a transmission channel that is used to transfer control information to mobile devices. The PDCCH may define how the paging channel and shared downlink channels are configured and it may define uplink transmission scheduling information to help coordinate access control to the radio system. A region of the frequency domain of a radio transmission channel may be defined to support the ePDCCH. Such a region may comprise one or more PRBs (physical resource blocks) . A physical resource block may denote a specific number of subcarriers being allocated to specific channels, like the ePDCCH.

The "downlink shared channel" may be a physical downlink shared channel (PDSCH) being used to send common user data and control information {such as paging messages) to all mobile devices operating within its coverage area.

According to an embodiment of the invention, the method further comprises receiving, by the user equipment, data transmissions on the identified subset of the plurality of radio resources.

As the UE knows which kind of signals to expect on the subset of the plurality of radio resources, the UE may receive these data transmissions.

According to a further embodiment of the invention, the information corresponds to a field indicator being

transmitted in the downlink control information (DCI) of the downlink control channel. The DCI may comprise for instance a flag for informing the UE about re-assigned resources. The UE may have prior knowledge about the meaning of any flags or other field indicators.

According to a further embodiment of the invention, the user equipment determines the subset of the plurality of radio resources to be zero, if the field indicator indicates that at least one of the plurality of radio resources of the downlink control channel is used.

According to this embodiment, the UE may receive the

information that at least one resource of the ePDCCH

transmits control information. Thus, the UE may assume that all resources of the ePDCCH comprise or transmit control information .

According to a further embodiment of the invention, the user equipment determines the subset of the plurality of radio resources to correspond to the plurality of radio resources, if the field indicator indicates that the plurality of radio resources of the downlink control channel is unused.

According to this embodiment, the UE may receive the

information that the resources of the ePDCCH are unused and thus may be re-used or re-scheduled for the PDSCH. Thus, the UE may assume that all resources of the ePDCCH are allocated to PDSCH and may transmit data.

According to a further embodiment of the invention, the information corresponds to a position of the plurality of radio resources of the downlink control channel within the radio transmission channel.

The UE may have a prior knowledge about possible positions of the resources of the ePDCCH when they are empty and rescheduled for the PDSCH. Thus, based on a specific position, for instance within the frequency domain, the UE may determine whether the resources are allocated to PDSCH or not. The position may also refer to a position of control

information within the ePDCCH.

The information, which corresponds to a position of the plurality of radio resources, may also correspond to an index which points to a specific position. The position may be inter alia a position within a search space of the UE .

According to a further embodiment of the invention, receiving information comprises determining whether a first of the plurality of radio resources of the downlink control channel comprises allocation information for the user equipment.

The UE may determine whether the first (and eventually a second) of the plurality of radio resources comprises or transmits control information and this control information comprises allocation information for the UE {i.e., to which resources the UE is allocated to transmissions.

According to a further embodiment of the invention, the method further comprises, if the first of the plurality of radio resources of the downlink control channel comprises a allocation information for the user equipment, determining the subset of the plurality of radio resources to correspon to the remaining radio resources of the plurality of radio resources .

For instance, the first (and eventually a second) of the plurality of radio resources comprises or transmits control information and this control information comprises the

allocation information for the UE (i.e., to which resources the UE is allocated to transmissions) . In this case, the UE may assume that the following resources of the ePDCCH are rescheduled to PDSCH and corresponds thus to the subset of radio resources. According to a further embodiment of the invention, the method further comprises, if the first of the plurality of radio resources of the downlink control channel comprises allocation information for the user equipment, determining the subset of the plurality of radio resources to be zero.

For instance, the first (and eventually a second) of the plurality of radio resources comprises or transmits control information and this control information comprises some allocation information for the UE {i.e., to which resources the UE is allocated to transmissions) . In this case, the UE may assume that the following resources of the ePDCCH are not empty and may transmit further control information (are still allocated to ePDCCH) .

According to a second aspect of the invention, there is provided a user equipment for identifying a subset of a plurality of radio resources of a downlink control channel, wherein the subset of radio resources is temporarily

allocated to a downlink shared channel, wherein the downlink control channel is used for sending downlink control

information being responsive for controlling a transmission between the user equipment and a base station via a radio transmission channel, wherein the downlink shared channel is used for sending common user data and control signals to the user equipment, wherein a plurality of radio resources of the radio transmission channel is allocated to the downlink control channel, and wherein a subset of the plurality of radio resources of the downlink control channel is

temporarily allocated to the downlink shared channel. The user equipment comprises a receiving unit being adapted to receive information being indicative for the subset of radio resources of the plurality of radio resources of the downlink control channel, which are temporarily allocated to the downlink shared channel, if they are unused by the downlink control channel, wherein the information is provided via at least one of the plurality of radio resources of the downlink control channel, and an identification unit being adapted to identify the subset of the plurality of radio resources of the downlink control channel based on the received

information, which subset is temporarily allocated to the downlink control channel.

The user equipment (UE) may be any type of communication en device, which is capable of providing the described

functionalities. The UE may be in particular a cellular mobile phone, a Personal Digital Assistant (PDA) , a noteboo computer, a printer and/or any other movable communication device .

The user equipment may comprise a receiving unit or receiver which is adapted for receiving signals from the base station, in particular as a ePDCCH or PDSCH. The user equipment may comprise a transmitting unit for transmitting signals. The transmitting unit may be a transmitter as known by a skilled person. The receiver and the transmitting unit may be

implemented as one single unit, for example as a transceiver. The transceiver or the receiver and the transmitting unit may be adapted to communicate with the base station via an antenna .

The user equipment may comprise an identification unit as described above. The identification unit of the user

equipment may be implemented for example as part of a control unit, like a CPU or a microcontroller. The identification unit and the transceiver may be coupled or may be implemented as one single unit. The identification unit may be adapted to perform identification procedures on signals received via the transceiver .

According to a third aspect of the invention, there is provided a base station being adapted to communicate with the user equipment having the above mentioned features. 1041

11

The base station may be any type of access point or point of attachment, which is capable of providing a wireless access to a cellular network system. Thereby, the wireless access may be provided for a user equipment or for any other network element, which is capable of communicating in a wireless manner. The base station may be an eNodeB, eNB, home NodeB or HNB, or any other kind of access point. A cell may be

assigned to the base station, wherein the base station may also serve more than one cell.

The base station may comprise a receiving unit, for example a receiver as known by a skilled person. The base station may also comprise a transmitting or sending unit, for example a transmitter. The receiver and the transmitter may be

implemented as one single unit, for example as a transceiver. The transceiver or the receiving unit and the sending unit may be adapted to communicate with the user equipment via an antenna .

The base station may also comprise a control unit for

instance for controlling or scheduling transmissions for the ePDCCH and the PDSCH, in particular for re-scheduling

resources of the ePDCCH to be used by the PDSCH. The control unit may be implemented as a single unit or may be

implemented for example as part of a standard control unit, like a CPU or a microcontroller.

According to a fourth aspect of the invention, there is provided a cellular network system. The cellular network system comprises a user equipment as described above. The cellular network system may also comprise a base station as described above.

Generally herein, the method and embodiments of the method according to the first aspect may include performing one or more functions described with regard to the second, third or fourth aspect or an embodiment thereof. Vice versa, the user equipment, the base station or the cellular network system and embodiments thereof according to the second, third and fourth aspect may include units or devices for performing one or more functions described with regard to the first aspect or an embodiment thereof.

According to a fifth aspect of the herein disclosed subject- matter, a computer program for identifying a subset of a plurality of radio resources of a downlink control channel is provided, the computer program being adapted for, when

executed by a data processor assembly, controlling the method as set forth in the first aspect or an embodiment thereof.

As used herein, reference to a computer program is intended to be equivalent to a reference to a program element and/or a computer readable medium containing instructions for

controlling a computer system to coordinate the performance of the above described method.

The computer program may be implemented as computer readable instruction code by use of any suitable programming language, such as, for example, JAVA, C++, and may be stored on a computer-readable medium (removable disk, volatile or nonvolatile memory, embedded memory/processor, etc.). The

instruction code is operable to program a computer or any other programmable device to carry out the intended functions. The computer program may be available from a network, such as the World Wide Web, from which it may be downloaded.

The herein disclosed subject matter may be realized by means of a computer program respectively software. However, the herein disclosed subject matter may also be realized by means of one or more specific electronic circuits respectively hardware. Furthermore, the herein disclosed subject matter may also be realized in a hybrid form, i.e. in a combination of software modules and hardware modules. In the above there have been described and in the following there will be described exemplary embodiments of the subject matter disclosed herein with reference to a cellular network system, a base station, a user equipment and a method of identifying a subset of a plurality of radio resources of a downlink control channel. It has to be pointed out that of course any combination of features relating to different aspects of the herein disclosed subject matter is also possible. In particular, some embodiments have been described with reference to apparatus type embodiments whereas other embodiments have been described with reference to method type embodiments. However, a person skilled in the art will gather from the above and the following description that, unless otherwise notified, in addition to any combination of features belonging to one aspect also any combination between features relating to different aspects or embodiments, for example even between features of the apparatus type

embodiments and features of the method type embodiments is considered to be disclosed with this application.

The aspects and embodiments defined above and further aspects and embodiments of the present invention are apparent from the examples to be described hereinafter and are explained with reference to the drawings, but to which the invention is not limited.

Brief Description of the Drawing

Figure 1 shows a cellular network system according to an exemplary embodiment of the present invention.

Figure 2 shows a frequency domain comprising ePDCCH regions. Figure 3 shows a user equipment and a base station within a cellular network system according to an exemplary embodiment of the invention.

It is noted that in different figures, similar or identical elements are provided with the same reference signs.

Detailed Description

In the following, embodiments of the herein disclosed subject matter are illustrated with reference to the drawings and reference to aspects of current standards, such as LTE .

However, such reference to current standards is only

exemplary and should not be considered as limiting the scope of the claims.

Figure 1 shows a cellular network system 100. The cellular network system 100 comprises at least one cell 103. The cell is assigned to a base station 102. A user equipment (UE) 101 is served by this base station.

The base station 102 transmits several signals to the user equipment 101 via a radio transmission channel. These signals comprise inter alia a downlink control channel (ePDCCH in the following) and a downlink shared channel (PDSCH in the following. The ePDCCH may be transmitted within specific radio resources of the radio transmission channel. However, if the ePDCCH does not require all assigned resources for its transmissions, some of the resources of the ePDCCH may be rescheduled or temporarily allocated to the PDSCH. The UE would nevertheless need to be informed in any way of this rescheduling .

Thus, the base station may transmit information to the UE comprising an indication for a re-scheduling of resources . The UE 101 may receive this information and may determine, based on the information, that a subset of resources of the ePDCCH is re-scheduled to the PDSCH. Based on the determined subset, the UE may identify the resources and may adapt its receiving behaviour.

As mentioned above, according to the latest discussions in view of LTE Rel.llt, there will be an ePDCCH region defined in frequency domain comprising all the PRBs on which the ePDCCH is transmitted. This is shown in Figure 2, wherein the frequency domain 200 comprises regions 202 being assigned to ePDCCH and regions 201 being assigned to other channels. It can occur that the ePDCCH does not require all of its assigned resources. As described above, it would be a waste of resources if some of the empty PRBs in the ePDCCH region (for example when there are few users allocated with large bandwidth) cannot be utilized for data transmission. It should be noted that the FDM approach shown in Figure 2 is exemplary by nature. In case the ePDCCH co-exists with legacy Rel'lO transmissions, the start of a subframe would carry the regular PDCCH (which can take between 1 and 3 OFDM symbols for system bandwidths of 3 MHz and above, while it can take 2 to 4 OFDM symbols for system bandwidth of 1.4 MHz). It should be noted that the ePDCCH region is semi-statically determined or configured (it can be different from subframe to subframe but in a pre-defined pattern) .

According to the herein described method, dynamic re-use of empty ePDCCH PRBs to PDSCH may be enabled. Specifically, the UE may be informed about the usage of ePDCCH PRBs through DCI (downlink control information) . It should be noted that this indication only relates to PDSCH puncturing in the PRBs where the UE is scheduled, and has no impact on the UE assumption on what is transmitted on ePDCCH PRBs outside the UE' s frequency allocation.

The information of the UE may be achieved inter alia

according to the following approachs: 1. There may be an explicit indication by one field in the DCI to indicate the UE about the usage of ePDCCH PRBs . For example, with 1-bit field, "1" indicates none of the ePDCCH PRBs in the UE's frequency allocation is used for control (UE may assume data transmission on those PRBs) , while "0" indicates at least one of the ePDCCH PRBs is used for control (UE may assume no data transmission on any of ePDCCH PRBs in its frequency allocation, and would assume that ePDCCH exists on all the pre-configured resources) . Of course, the UE might only ignore the physical PRB resources that coincide with its own PDSCH allocation.

2. There may be an implicit indication by a DL

assignment position. For example, if the frequency allocation contains some empty ePDCCH PRBs, the DL assignment may be placed at a special position in the UE's search space. The UE may then assume data transmission on those ePDCCH PRBs.

3. There may be an implicit indication by the ePDCCH position. For example, if the frequency allocation contains some empty ePDCCH PRBs, the ePDCCH may be frequency modulated with the PDSCH within one PRB. The UE may assume data

transmission on those ePDCCH PRBs.

The last two approaches may be implemented according to the following. One implementation could be the position of the actual PRB (or more accurately PRB pair) that the ePDCCH is located upon. For instance, in case one UE is configured to monitor a set of PRB pairs (a, b, c, and d) . Then a rule could be applied that in case a UE is scheduled using the first two PRB pairs, the eNB would not assign any other UE control channels to this PRB pair, and the resources could here be reused. Further, another implementation could be that the UE may assume that in case it is finding its allocation in PRB pair a or b, all PRB pairs are potentially part of the scheduled resources (in the resource allocation map) . A further implementation could be that the search space within a PRB pair may be considered. Here, it can be assumed that each PRB pair can be split into a number (4) of enhanced control channel elements (E-CCE) , and as above, in case one UE is scheduled using one or two pre-agreed of these, the UE may know that the remainder of the E-PDCCH resources are used for PDSCH data (given back to the data domain) .

Figure 2 shows a cellular network system 200 according to a further exemplary embodiment of the invention. The cellular network system comprises a base station 102 and a user equipment 101.

The user equipment 101 comprises a receiving unit 301 being adapted to receive information being indicative for a subset of radio resources of a plurality of radio resources of a downlink control channel, which are temporarily allocated to a downlink shared channel, if they are unused by the downlink control channel. This information is provided via at least one of the plurality of radio resources of the downlink control channel. The user equipment comprises further an identification unit 302 being adapted to identify the subset of the plurality of radio resources of the downlink control channel 202 based on the received information, which subset is temporarily allocated to the downlink control channel.

As mentioned above, the downlink control channel is used for sending downlink control information being responsive for controlling a transmission between the user equipment and the base station via the radio transmission channel. The downlink shared channel is used for sending common user data and control signals to the user equipment 101. A plurality of radio resources of the radio transmission channel is

allocated to the downlink control channel, and a subset of the plurality of radio resources of the downlink control channel is temporarily allocated to the downlink shared channel, for instance when some of the resources of the downlink control channel are not used and thus empty.

The user equipment (UE) may be any type of communication end device, which is capable of providing the described

functionalities. The UE may be in particular a cellular mobile phone, a Personal Digital Assistant (PDA), a notebook computer, a printer and/or any other movable communication device .

The user equipment may comprise a receiving unit or receiver which is adapted for receiving signals from the base station, The user equipment may comprise a transmitting unit for transmitting signals. The transmitting unit may be a

transmitter as known by a skilled person. The receiver and the transmitting unit may be implemented as one single unit, for example as a transceiver 301. The transceiver or the receiver and the transmitting unit may be adapted to

communicate with the base station via an antenna.

The identification unit 302 of the user equipment may be implemented for example as part of a control unit, like a CPU or a microcontroller. The identification unit and the

transceiver may be coupled or may be implemented as one single unit.

The base station may be any type of access point or point of attachment, which is capable of providing a wireless access to a cellular network system. Thereby, the wireless access may be provided for a user equipment or for any other network element, which is capable of communicating in a wireless manner. The base station may be an eNodeB, eNB, home NodeB or HNB, or any other kind of access point.

implemented as one single unit, for example as a transceiver 303. The transceiver or the receiving unit and the sending unit may be adapted to communicate with the user equipment via an antenna.

The base station may also comprise a control unit 304 for instance for controlling or scheduling transmission to the user equipment, in particular via the downlink control channel and the downlink shared channel. The control unit may be implemented as a single unit or may be implemented for example as part of a standard control unit, like a CPU or a microcontroller .

Having regard to the subject matter disclosed herein, it should be mentioned that, although some embodiments refer to a "base station", "eNB", etc., it should be understood that each of these references is considered to implicitly disclose a respective reference to the general term "network

component" or, in still other embodiments, to the term

"network access node". Also other terms which relate to specific standards or specific communication techniques are considered to implicitly disclose the respective general term with the desired functionality.

It should further be noted that a user equipment or base station as disclosed herein is not limited to dedicated entities as described in some embodiments. Rather, the herein disclosed subject matter may be implemented in various ways in various locations in the communication network while still providing the desired functionality.

According to embodiments of the invention, any suitable entity {e.g. components, units and devices) disclosed herein, e.g. the identification unit, are at least in part provided in the form of respective computer programs which enable a processor device to provide the functionality of the respective entities as disclosed herein. According to other embodiments, any suitable entity disclosed herein may be provided in hardware. According to other - hybrid - embodiments, some entities may be provided in software while other entities are provided in hardware.

It should be noted that any entity disclosed herein (e.g. components, units and devices) are not limited to a dedicated entity as described in some embodiments. Rather, the herein disclosed subject matter may be implemented in various ways and with various granularities on device level while still providing the desired functionality. Further, it should be noted that according to embodiments a separate entity (e.g. a software module, a hardware module or a hybrid module) may be provided for each of the functions disclosed herein.

According to other embodiments, an entity (e.g. a software module, a hardware module or a hybrid module (combined software/hardware module) ) is configured for providing two or more functions as disclosed herein.

It should be noted that the term "comprising" does not exclude other elements or steps. It may also be possible in further refinements of the invention to combine features from different embodiments described herein above. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

List of reference signs:

100 Cellular network system

101 User equipment

102 Base station

103 Cell

200 Frequency domain comprising ePDCCH

201 non-ePDCCH region

202 ePDCCH region

300 Cellular network system

301 Transceiver of user equipment

302 Identification unit of user equipment 303 Transceiver of base station

304 Control unit of base station

Claims

What is Claimed is :

1. A method for identifying a subset of a plurality of radio resources of a downlink control channel (202), wherein the subset of radio resources is temporarily allocated to a downlink shared channel, wherein the downlink control channel (202) is used for sending downlink control information being responsive for controlling a transmission between a user equipment (101) and a base station (102) via a radio

transmission channel (200) , wherein the downlink shared channel is used for sending common user data and control signals to the user equipment (101), wherein a plurality of radio resources (202) of the radio transmission channel is allocated to the downlink control channel, and wherein a subset of the plurality of radio resources of the downlink control channel is temporarily allocated to the downlink shared channel, the method comprising

receiving, by the user equipment (101), information being indicative for the subset of radio resources of the plurality of radio resources of the downlink control channel (202) , which are temporarily allocated to the downlink shared channel, if they are unused by the downlink control channel, wherein the information is provided via at least one of the plurality of radio resources of the downlink control channel, and

identifying, by the user equipment (101) , the subset of the plurality of radio resources of the downlink control channel (202) based on the received information, which subset is temporarily allocated to the downlink control channel.

2. The method as set forth in any one of the preceding claims, the method further comprising

receiving, by the user equipment (101) , data

transmissions on the identified subset of the plurality of radio resources.

3. The method as set forth in any one of the preceding claims, wherein the information corresponds to a field indicator being transmitted in the downlink control

information of the downlink control channel (202).

4. The method as set forth in claim 3, wherein the user equipment (101) determines the subset of the plurality of radio resources to be zero, if the field indicator indicates that at least one of the plurality of radio resources of the downlink control channel (202) is used.

5. The method as set forth in any one of the claims 3 or 4, wherein the user equipment (101) determines the subset of the plurality of radio resources to correspond to the plurality of radio resources, if the field indicator indicates that the plurality of radio resources of the downlink control channel (202) is unused.

6. The method as set forth in any one of the preceding claims, wherein the information corresponds to a position of the plurality of radio resources of the downlink control channel (202) within the radio transmission channel (200).

7. The method as set forth in any one of the preceding claims, wherein receiving information comprises determining whether a first of the plurality of radio resources of the downlink control channel (202) comprises allocation

information for the user equipment (101) .

8. The method as set forth in claim 7, wherein the method further comprises

if the first of the plurality of radio resources of the downlink control channel (202) comprises allocation

information for the user equipment (101), determining the subset of the plurality of radio resources to correspond to the remaining radio resources of the plurality of radio resources .

9. The method as set forth In claim 7, wherein the method further comprises

information for the user equipment (101), determining the subset of the plurality of radio resources to be zero.

10. A user equipment (101) for identifying a subset of a plurality of radio resources of a downlink control channel (202) , wherein the subset of radio resources is temporarily allocated to a downlink shared channel, wherein the downlink control channel (202) is used for sending downlink control information being responsive for controlling a transmission between the user equipment (101) and a base station (102) via a radio transmission channel (200) , wherein the downlink shared channel is used for sending common user data and control signals to the user equipment (101), wherein a plurality (202) of radio resources of the radio transmission channel (200) is allocated to the downlink control channel, and wherein a subset of the plurality of radio resources of the downlink control channel (202) is temporarily allocated to the downlink shared channel, the user equipment (101) comprising

a receiving unit (301} being adapted to receive

information being indicative for the subset of radio

resources of the plurality of radio resources of the downlink control channel (202) , which are temporarily allocated to the downlink shared channel, if they are unused by the downlink control channel (202) , wherein the information is provided via at least one of the plurality of radio resources of the downlink control channel, and

an identification unit (302) being adapted to identify the subset of the plurality of radio resources of the

downlink control channel (202) based on the received

11. A base station (102} being adapted to communicate with the user equipment (101} as set forth in claim 10.

12. A cellular network system (100), the cellular network system comprising a user equipment (101) as set forth in claim 10.