Patent Description:
In 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) Release <NUM>, i.e., a legacy system, a Physical Downlink Control CHannel (PDCCH) is presented in several initial Orthogonal Frequency Division Multiplexing (OFDM) symbols. The number of OFDM symbols used for the PDCCH is indicated in a Physical Control Format Indication CHannel (PCFICH) in a first OFDM symbol. Each PDCCH includes L Control Channel Elements (CCEs), where L=<NUM>, <NUM>, <NUM>, or <NUM>, representing different CCE aggregation levels. Each CCE includes <NUM> Resource Element Group (REG) spreading on the transmission bandwidth.

Upon receiving the PDCCH, the UE blindly attempts decoding the PDCCH on its search space. The search space contains multiple possible CCE starting indexes and CCE aggregation levels. The UE attempts to decode an expected Downlink Control Information (DCI) format based in this assumption. If a Cyclic Redundancy Check (CRC) passes, the UE assumes a DCI format is successfully received. In legacy 3GPP systems, e.g., 3GPP LTE Releases <NUM>-<NUM>, the PDCCH is transmitted using transmit diversity when multiple antennas are available, and the UE uses common reference signals inside the PDCCH region for decoding. The common reference signals are cell-specific.

<CIT> discloses systems and methodologies facilitate defining a new control region over resources allocated for communicating general non-control data in a legacy network specification. <CIT> discloses techniques for supporting communication for different user equipment on different system bandwidths.

There are problems related to transmitting data in restricted resource circumstance.

The downlink transmission method includes determining, by the base station, whether resources for a terminal are restricted; determining a sub-set of resource blocks for the terminal from among all resource blocks, if the resources for the terminal are restricted; transmitting information about the sub-set of the resource blocks to the terminal; and allocating a first sub-sub-set of the sub-set of the resource blocks for control channel transmission, and a second sub-sub-set of the sub-set of the resource blocks for data channel transmission.

An aspect of the present invention is to provide apparatuses and methods for a wireless system to schedule both control and data channel within the same bandwidth, wherein resource blocks in the frequency domain are assigned to a UE, and the assigned resource blocks are selected such that the UE will have better channel gain on those selected resource blocks.

The above and other aspects, features, and advantages of certain embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:.

Another aspect of the present invention is to impose a constraint on resource scheduling for both control and data channels, such that a resource allocated to a data channel must be overlapped by at least a resource block used by a control channel.

By introducing such resource allocation constraints to the system, the number of information bits needed to be carried by the DCI can be reduced, reducing system overhead and improving system performance.

In accordance with an aspect of the present invention a method by a user equipment in a wireless communication system is provided according to claim <NUM>.

In accordance with an aspect of the present invention a method by a base station in a wireless communication system is provided according to claim <NUM>.

In accordance with an aspect of the present invention a user equipment in a wireless communication system is provided according to claim <NUM>.

In accordance with an aspect of the present invention a base station in a wireless communication system is provided according to claim <NUM>.

Examples and technical descriptions of apparatuses, products and/or methods in the description and/or drawings which are not covered by the claims are presented not as embodiments of the invention but as background art or examples useful for understanding the invention.

Various embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, specific details such as detailed configuration and components are merely provided to assist the overall understanding of these embodiments of the present invention. Therefore, it should be apparent to those skilled in the art that various changes and modifications of the embodiments described herein can be made without departing from the scope of the present invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

In an evolutionary system based on LTE Release <NUM>, such as Release <NUM> and beyond, the PDCCH might be further extended into the legacy data channel region. For example, a system can either assign one or a few OFDM symbols, e.g., a next one or two OFDM symbols following the legacy PDCCH symbols in a subframe, or assign a sub-set of Resource Blocks (RBs) for extended PDCCH.

<FIG> illustrates two examples of a subframe including extended PDCCH regions. Referring to <FIG>, in subframes <NUM> and <NUM>, each of the symbols to the right of those indicated as being within the legacy PDCCH region, except those indicated as common reference signals, can be considered as being part of the legacy data channel region. In subframe <NUM>, the PDCCH is extended into the legacy data channel region, by assigning a next symbol following the symbols of the legacy PDCCH region as an extended PDCCH region. Further, in subframe <NUM>, the PDCCH is extended into the legacy data channel region, by assigning all of the symbols of the legacy data channel region in RB <NUM> as an extended PDCCH region.

For the extended PDCCH, because it can be either locally or distributed located in the frequency domain, a system can exploit multi-user gain by scheduling preferable sub-bands with better channel gain to respective users. In general, several key objectives have been proposed for the extended PDCCH. First, the resources available for the PDCCH are extended, in particular for carrier aggregation as well as for other features that also increase the required resources for the PDCCH, such as multiple user multiple input/multiple output (MU-MIMO). Second, interference mitigation of the PDCCH for heterogeneous networks might be performed as the extended PDCCH is defined in the PDSCH region, and therefore RB-based interference management and coordination can be performed.

In a wireless OFDM system according to an embodiment of the present invention, a subset of RBs included in the full bandwidth are selected for a particular UE. The subset may be different from UE to UE, and the size of the subset, i.e., the number of RBs included in the subset, may vary.

More specifically, a base station (or eNB) determines whether or not resource restriction should be applied to a UE and selects RBs for the UE based on information and feedback of the UE, e.g., channel information on a subband, expected traffic for the UE, channel status feedback information, etc. When the resource restriction decision is made, the eNB sends a configuration message to the UE, informing the UE of its assigned control and data channels. For example, the configuration message can be transmitted via high layer Radio Resource Control (RRC) message, hereinafter referred to as an RRC resource restriction message. Further, the RB sub-set configuration may be semi-statically configured, i.e., once configured, it is not to be expected to be reconfigured for a certain period of time, e.g., several radio frames.

After the UE is allocated with the RB sub-set restriction, it assumes all control and data payload will be transmitted using the allocated RBs. Basically, the UE assumes the allocated subset of RBs as a virtual system bandwidth, and the resource partitioning and assignment will be done based on this assumption.

Because the size of the virtual system bandwidth is reduced as indicated by the configuration message, the bits used for resource allocation can be accordingly reduced.

For a system bandwidth with NRB RBs, out of which <MAT> RBs are allocated to a UE u, the RRC configuration can be an NRB-bit bitmap indicated, if each RB is allocated for the UE. In 3GPP, the number of bits used for resource allocation is shown below.

With a resource restriction method in accordance with an embodiment of the present invention, the number of bits used for resource allocation within an RB subset is reduced as shown below.

Because a new DCI format size with the resource restriction method will be variable and user-specific, restrictions should be imposed on the value of <MAT>, such that it does not conflict with other DCIs format sizes. The restricted values of <MAT> will depend on the system bandwidth.

<FIG> illustrates resource allocation restriction for a PDCCH and PDSCH according to the present invention. Specifically, <FIG> illustrates an example of type <NUM> resource allocation, where a <NUM>-RB system is presented.

Referring to <FIG>, the RRC resource restriction message indicates that RBs <NUM>-<NUM> are allocated as the RB subset for UE u, and a field for indicating the PDSCH data resource in a DCI format assigns RBs <NUM>-<NUM> for PDSCH transmission. In this example, <NUM> bit (RB <NUM>)is saved for DCI format for downlink allocation. The savings will be more significant if the system bandwidth increases and the subset size decreases.

<FIG> is a flowchart illustrating an evolved Node B (eNB) method of resource allocation restriction according to the present invention.

Referring to <FIG>, the eNB performs initial access for a UE in step <NUM>. For example, the eNB and UE can set up communication as defined in the legacy systems.

In step <NUM>, the eNB collects UE's feedback and other information. For example, the other information may include at least one of channel information on a subband, expected traffic of the UE, and channel status feedback information.

Based on the collected information, the eNB performs scheduling for the UE in step <NUM>, and determines whether or not resource restriction should be applied to the UE in step <NUM>.

When resource restriction is applied (or modified from a previous restriction), the eNB sends a message, i.e., an RRC resource restriction message, to the UE to activate( or update) the resource restriction in step <NUM>. For example, the RRC resource restriction message can be a bitmap indicating which RBs or which predefined sub-bands are allocated to the UE. The RRC resource restriction message can also take a compressed version for RB indication, e.g., the tree structure indication illustrated in <FIG>, where each node indicates all the branches under it.

In step <NUM>, the eNB transmits PDCCH and PDSCH payload to the UE using the restricted resources.

When resource restriction is not applied in step <NUM>, legacy operations are performed without sending any configuration to the UE in step <NUM>. Alternatively, in step <NUM>, the eNB can indicate all of the RBs or subbands included in the system bandwidth, such that no resource restriction is applied.

In step <NUM>, the eNB determines whether communication between the eNB and the UE is finished. When the communication is not finished, the method returns to step <NUM>, where the eNB collects the UE's feedback and other information. When the communication is finished, the method ends.

<FIG> is a flowchart illustrating a UE method of resource allocation restriction according to the present invention.

Referring to <FIG>, the UE performs initial access for the eNB in step <NUM>. For example, the UE and the eNB can set up communication as defined in the legacy systems.

In step <NUM>, the UE transmits feedback and other information to the eNB. As described above, the other information may include channel information on a subband, expected traffic of the UE, channel status feedback information, etc..

In step <NUM>, the UE receives a message from the eNB. The message may be an RRC resource restriction message, such as a bitmap indicating which RBs or which predefined sub-bands are allocated to the UE.

In step <NUM>, the UE decodes the message and determines whether or not resource restriction is applied to the UE.

When the UE receives the RRC resource restriction message, the UE re-indexes its available RBs and re-partitions resources for potential extended PDCCH usage based on the RRC resource restriction message in step <NUM>.

In step <NUM>, the UE decodes PDCCH and PDSCH payload received within the restricted resources. More specifically, the eNB sends both the control and data channels to the UE, as scheduled by the RRC resource restriction message. The UE first tries extended PDCCH blind decoding on the modified search spaces, which are restricted in the RB subset. Because the PDSCH data channel transmission will also be restricted within the RB subset, the size of related DCI format will also be changed. The UE also takes this into account when doing the control channel blind decoding. After decoding the extended PDCCH, the UE locates its assigned PDSCH resource within the RB subset, and then decodes the data carried therein.

When the UE does not receive an RRC resource restriction message in step <NUM>, legacy reception for PDCCH and PDSCH is performed in step <NUM>. Alternatively, the UE could receive an indication that all of the RBs or subbands of the system bandwidth are available, so that no resource restriction is applied.

In step <NUM>, the UE determines whether communication between the UE and the eNB is finished. If the communication is not finished, the method returns to step <NUM>; otherwise, the method is ended.

In accordance with another embodiment of the present invention, a system can mandate common resources for both control and data channels, such that the resources for the two channels can be bonded in frequncy domain, and the resource allocation indication field size can be reduced accordingly. For example, the resource block of control channel and the resurce block of data channel have at least one resource block in common.

There are multiple alternatives for defining a common resource. For example, a common resource can be defined such that a PDSCH must include at least a first RB in which an extended PDCCH is located. Alternatively, a common resource can be defined such that a PDSCH must include at least a first few RBs (e.g., in granularity of a RB group as defined in 3GPP specification) in which an extended PDCCH is located. A common resource can also be defined such that a PDSCH must include all of the RBs occupied by the extended PDCCH.

In a system where an RB is exclusively allocated for an extended PDCCH, the neighboring one or several RBs next to the first extended PDCCH RB can be mandated to be included in PDSCH resource.

<FIG> illustrates resource allocation mandating a PDCCH RB to include a PDSCH resource according to the present invention. Specifically, <FIG> illustrates two RBs used for extended PDCCH transmission.

Referring to <FIG>, in a system where a PDCCH resource is mandated to be a subset of PDSCH transmission, only code points inclusive of the two PDCCH RBs are used for PDSCH resource allocation. These code points exclusive of either of the two PDCCH RBs are not considered for PDSCH resource allocation. The possible code point will be significantly reduced and so be done for the resource allocation field size, accordingly. In <FIG>, a size of a resource allocation field size depends on a starting location of a PDCCH. Further, when the UE is attempting blind decoding, the UE will assume different DCI format size for each search space.

<FIG> is a flow chart illustrating an eNB resource allocation mandating method according to an embodiment of the present invention.

Referring to <FIG>, the eNB performs initial access for the UE in step <NUM>. For example, the eNB and UE can set up communication as defined in the legacy systems.

In step <NUM>, the eNB collects UE's feedback and other information. Again, the other information may include channel information on a subband, expected traffic of the UE, channel status feedback information, etc..

Based on the collected information, the eNB performs scheduling for the UE in step <NUM>, and determines whether or not resource mandating should be applied to the UE in step <NUM>.

When resource mandating is applied (or modified from a previous mandate), the eNB sends a message to the UE to activate (or update) the resource mandating in step <NUM>. For example, the message may be an RRC message, which includes a short flag indicating whether a resource mandating mode is on or off. Additionally, there can be another independent RRC message restricting the resource to be used by the PDCCH. In step <NUM>, the eNB transmits PDCCH and PDSCH payloads using the mandated resources.

When resource mandating is not applied in step <NUM>, legacy operations are performed, without sending any configuration to the UE in step <NUM>. Alternatively, to the eNB may indicate all RBs or subbands of the system bandwidth, so that no resource mandating is applied.

In step <NUM>, the eNB determines whether or not communication between the eNB and the UE is finished. If the communication is not finished, the method returns to step <NUM>, where the eNB collects the UE's feedback and other information.

<FIG> is a flow chart illustrating a UE resource allocation mandating method according to the present invention.

In step <NUM>, the UE transmits feedback of the UE and other information. The other information may include channel information on a subband, expected traffic of the UE, channel status feedback information, etc..

In step <NUM>, the UE receives a message from the eNB. The message may include resource mandating information, i.e., the message may be a RRC message for resource mandating.

In step <NUM>, the UE decodes the received message and determines whether or not resource mandating is applied to the UE.

When resource mandating is applied, the UE assumes that the PDSCH resource allocated to it will be mandated as indicated therein. Accordingly, in step <NUM>, the user re-generates search spaces and respective DCI sizes, based on the message.

In step <NUM>, the UE decodes the PDCCH and PDSCH payload included in the mandated resources. More specifically, the eNB sends both the control and data channels to the UE as scheduled by the RRC signals. After decoding the extended PDCCH, the UE locates its assigned PDSCH resource within an RB subset, and then decodes the data carried therein.

When the UE does not receive resource mandating in step <NUM>, legacy reception is performed for the PDCCH and the PDSCH in step <NUM>. Alternatively, to the eNB may indicate all of the RBs or subbands of the system bandwidth, so that no resource mandating is applied.

In step <NUM>, the UE determines whether or not communication between the UE and the eNB is finished. If the communication is not finished, the method returns to step <NUM>; otherwise, the method ends.

<FIG> is a block diagram illustrating a base station according to the present invention.

Referring to <FIG>, the base station (or eNB) includes a transceiver <NUM> and a controller <NUM>. The transceiver <NUM> transmits and receives signals, e.g., with a UE. The controller <NUM>, e.g., a processor, controls the base station to operate according to the methods described above and illustrated in <FIG> and <FIG>.

<FIG> is a block diagram illustrating a UE according to the present invention.

Referring to <FIG>, the UE includes a transceiver <NUM> and a controller <NUM>. The transceiver <NUM> transmits and receives signals, e.g., with an eNB. The controller <NUM>, e.g., a processor, controls the UE to operate according to the methods described above and illustrated in <FIG> and <FIG>.

Claim 1:
A method by a user equipment, UE, in a wireless communication system, the method comprising:
receiving (<NUM>) bit map information on a set of resource blocks through radio resource control, RRC, signaling from a base station, wherein resource blocks for a control channel for the UE are restricted by the set of resource blocks;
receiving (<NUM>), from the base station, control information for downlink data on the control channel identified based on the bit map information; and
receiving (<NUM>), from the base station, the downlink data on a data channel based on the control information,
wherein the control information is received on at least one control channel resource, the at least one control channel resource being included in the set of resource blocks, and
wherein a search space for the control channel of the UE is defined based on an aggregation level, a number of the at least one control channel resource included in the set of resource blocks, and a number of candidates associated with the control channel.