The present invention relates to a device and a method used in a wireless communication system, and more particularly, to a device and a method of handling common search spaces (CSSs) in a wireless communication system.
A control resource set (CORESET) and at least one search space in a slot are configured for a communication device such that the communication device can receive a downlink (DL) control information (DCI) from a base station (BS) in the slot. However, when the BS transmits messages to multiple (or all) communication devices in a cell, if these communication devices have been configured to receive DCIs in search spaces in different CORESETs, respectively, the same DCI is transmitted in different CORESETs and time-frequency resources are wasted.
The present invention therefore provides a communication device for handling CSSs to solve the abovementioned problem.
A BS for handling CSSs comprises at least one storage device for storing instructions and at least one processing circuit coupled to the at least one storage device. The at least one processing circuit is configured to execute the instructions stored in the at least one storage device. The instructions comprise transmitting a first signaling for configuring a first group CSS on a first CORESET for a first communication device, to the first communication device; transmitting a second signaling for configuring a second group CSS on a second CORESET for a second communication device, to the second communication device; transmitting a third signaling for configuring the first group CSS on the first CORESET for the second communication device, to the second communication device; transmitting a first DCI via the first group CSS to the first communication device and the second communication device; and transmitting a second DCI to the second communication device via the second group CSS.
A communication device for handling CSSs comprises at least one storage device for storing instructions and at least one processing circuit coupled to the at least one storage device. The at least one processing circuit is configured to execute the instructions stored in the at least one storage device. The instructions comprise receiving a signaling for configuring a group CSS on a CORESET, from a BS; determining a time-frequency location of the CORESET according to the signaling; determining the group CSS on the CORESET according to the signaling; and decoding a DCI received via the first group CSS from the BS.
A communication device for handling CSSs comprises at least one storage device for storing instructions and at least one processing circuit coupled to the at least one storage device. The at least one processing circuit is configured to execute the instructions stored in the at least one storage device. The instructions comprise receiving a signaling for configuring a group CSS on a CORESET, from a BS; determining a time-frequency location of the CORESET and the group CSS on the CORESET, according to the signaling; decoding a DCI received via the group CSS from the BS, wherein the DCI comprises an uplink (UL) grant or a DL assignment.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
In
A communication device maybe a user equipment (UE), a machine type communication (MTC) device, a mobile phone, a laptop, a tablet computer, an electronic book, a portable computer system, a vehicle, or an aircraft. In addition, the network and the communication device can be seen as a transmitter or a receiver according to direction of transmission (i.e., transmission direction), e.g., for an uplink (UL), the communication device is the transmitter and the network is the receiver, and for a downlink (DL), the network is the transmitter and the communication device is the receiver.
In order to enable UEs with different bandwidth capabilities to efficiently access the same new radio (NR) carrier irrespective of the NR carrier bandwidth, a NR system supports a control region of which the bandwidth is smaller than a carrier bandwidth. The control region may be termed as a control resource set (CORESET) (or a control subband). A carrier bandwidth may include at least one CORESET, and each UE may attempt to blindly decode a DL control information (DCI) in a certain CORESET in a slot. In addition, a UE may be configured to decode a DCI in the at least one CORESET. In a frequency domain, a CORESET comprises several physical resource blocks (PRBs). These PRBs may or may not be frequency contiguous such that a BS can transmit a DCI in distributed PRBs to provide frequency diversity.
As in a LTE system, a structure of a control region is based on control-channel elements (CCEs). The control region includes a number of CCEs. One physical DL control channel (PDCCH) may use 1, 2, 4, or 8 CCEs to transmit a DCI. The number of CCEs for a PDCCH (called aggregation level) depends on a channel-coding rate and a size of a DCI payload. Accordingly, a dynamic rate control fora PDCCH may be performed. For example, in situations with disadvantageous channel conditions for a UE, a BS can use a larger number of CCEs (lower code rate) to transmit a DCI to the UE compared with situations with advantageous channel conditions.
A CCE is the smallest unit of a blind decoding attempt. A UE blindly decodes a DCI in 1, 2, 4 and 8 CCEs, which are at different aggregation levels, respectively. Although a CCE structure reduces the number of blind decoding attempts, the reduction may not be sufficient. Monitoring all CCEs in the control region results an impact on the implementation complexity of the UE. Therefore, in order to limit the number of CCEs at each aggregation level that the UE is supposed to monitor, a search space is defined for the LTE system. A search space is a set of candidate control channels formed by CCEs at a given aggregation level, which a UE is supposed to attempt to decode. Because the search spaces should differ for different UEs, each UE in a cell has a UE-specific search space (USS) at each aggregation level. In addition, a common search space (CSS) is also defined for the control region in the LTE system to let multiple UEs be addressed at the same time. Specifically, in the LTE system, a CSS at a given aggregation level is a set of candidate control channels formed by CCEs which is monitored by all UEs in a cell. The use of the CSS may provide necessary system information for multiple UEs in a cell. Therefore, in addition to USSs , each UE must blindly monitor the CSSs for a PDCCH in a slot.
A group CSS is defined as a search space monitored by part of the UEs in the cell. Several methods are proposed for applying group CSSs.
In the following embodiments, a UE is used for representing a communication device in
Step 300: Start.
Step 302: Transmit a first signaling for configuring a first group CSS on a first CORESET for a first UE, to the first UE.
Step 304: Transmit a second signaling for configuring a second group CSS on a second CORESET for a second UE, to the second UE.
Step 306: Transmit a third signaling for configuring the first group CSS on the first CORESET for the second UE, to the second UE.
Step 308: Transmit a first DCI via the first group CSS to the first UE and the second UE.
Step 310: Transmit a second DCI to the second UE via the second group CSS.
Step 312: End.
According to the process 30, the BS transmits a first signaling for configuring a first group CSS on a first CORESET for a first UE, to the first UE. The BS transmits a second signaling for configuring a second group CSS on a second CORESET for a second UE, to the second UE. The BS transmits a third signaling for configuring the first group CSS on the first CORESET for the second UE, to the second UE. Then, the BS transmits a first DCI via the first group CSS to the first UE and the second UE. The BS transmits a second DCI to the second UE via the second group CSS. That is, a specific group CSS is configured for multiple UEs to receive a specific DCI. The BS configures multiple UEs (e.g., the first UE and the second UE) to monitor the same group CSS (e.g., the first group CSS) so that the UEs receive the same DCI (e.g., the first DCI) on the same time-frequency resource, and the waste of the time-frequency resource is reduced.
Realization of the process 30 is not limited to the above description. The following examples may be applied to the process 30.
In one example, the first signaling is a random access response (RAR) signaling, a Msg.4 signaling or a radio resource control (RRC) signaling. In one example, the first signaling comprises first information of at least one of a time-frequency location of the first CORESET, a plurality of PDCCH candidates of the first group CSS, an aggregation level of the first group CSS, and a number of the plurality of PDCCH candidates for the first group CSS.
In one example, the second signaling is a RAR signaling, a Msg.4 signaling or a RRC signaling. In one example, the second signaling comprises second information of at least one of a time-frequency location of the second CORESET, a plurality of PDCCH candidates of the second group CSS, an aggregation level of the second group CSS, and a number of the plurality of PDCCH candidates for the second group CSS.
In one example, the third signaling and the first signaling is a same signaling or different signalings.
In one example, the BS transmits the first signaling for configuring the first group CSS on the first CORESET for a third UE, to the third UE, and transmits the first DCI via the first group CSS to the third UE. That is, the first UE and the third UE can be seen as the UEs in a same UE group which is defined as a group of UEs whose search spaces are configured in the same time-frequency resource by the BS. The BS configures the UEs in the same UE group to receive the same DCI(s) via the same group CSS on the same CORESET.
In one example, the BS transmits the second signaling for configuring the second group CSS on the second CORESET for a fourth UE, to the fourth UE. The BS transmits the third signaling for configuring the first group CSS on the first CORESET for the fourth UE, to the fourth UE. The BS transmits the first DCI to the fourth UE via the first group CSS. The BS transmits the second DCI to the fourth UE via the second group CSS. That is, the second UE and the fourth UE can be seen as the UEs in a same UE group. The BS configures the UEs in the same UE group to receive the same DCI(s) via the same group CSS on the same CORESET.
Step 400: Start.
Step 402: Receive a signaling for configuring a group CSS on a CORESET, from a BS.
Step 404: Determine a time-frequency location of the CORESET according to the signaling.
Step 406: Determine the group CSS on the CORESET according to the signaling.
Step 408: Decode a DCI received via the group CSS from the BS.
Step 410: End.
According to the process 40, the UE receives a signaling for configuring a group CSS on a CORESET, from a BS . Then, the UE determines a time-frequency location of the CORESET and determines the group CSS on the CORESET according to the signaling. The UE (e.g., blindly) decodes a DCI received via the group CSS from the BS. That is, the UE is configured to monitor an individual group CSS and to decode the DCI received on the individual group CSS from the BS.
Realization of the process 40 is not limited to the above description. The following examples may be applied to the process 40.
In one example, the signaling is a RAR signaling, a Msg.4 signaling or a RRC signaling.
In one example, the UE determines at least one of a plurality of PDCCH candidates of the group CSS, an aggregation level of the group CSS, and a number of the plurality of PDCCH candidates for the group CSS, according to the signaling.
Step 600: Start.
Step 602: Determine that a first search space on a first CORESET is a first group CSS.
Step 604: Determine that a second search space on a second CORESET is a second group CSS.
Step 606: Transmit a first signaling for configuring the first group CSS on the first CORESET for a first UE, to the first UE.
Step 608: Transmit a second signaling for configuring the second group CSS on the second CORESET for a second UE, to the second UE.
Step 610: Transmit a third signaling for configuring the first group CSS on the first CORESET for the second UE, to the second UE.
Step 612: Transmit a first DCI via the first group CSS to the first UE and the second UE.
Step 614: Transmit a second DCI via the second group CSS to the second UE.
Step 616: End.
According to the process 60, the BS determines (e.g., pre-determines) that a first search space on a first CORESET is a first group CSS, and determines (e.g., pre-determines) that a second search space on a second CORESET is a second group CSS. Then, the BS transmits a first signaling for configuring the first group CSS on the first CORESET for a first UE, to the first UE. The BS transmits a second signaling for configuring the second group CSS on the second CORESET for a second UE, to the second UE. The BS transmits a third signaling for configuring the first group CSS on the first CORESET for the second UE, to the second UE. The BS transmits a first DCI via the first group CSS to the first UE and the second UE. The BS transmits a second DCI via the second group CSS to the second UE. That is, a specific group CSS is configured for one or multiple UEs to receive a specific DCI. The BS configures multiple UEs (i.e., the first UE and the second UE) to monitor the same group CSS (i.e., the first group CSS) so that the UEs receive the same DCI (i.e., the first DCI) on the same time-frequency resource, which reduces the waste of the time-frequency resource
Realization of the process 60 is not limited to the above description. The following examples may be applied to the process 60.
In one example, the first CORESET may be the second CORESET.
In one example, the first signaling is a RAR signaling, a Msg.4 signaling or a RRC signaling. In one example, the first signaling comprises first information of at least one of a time-frequency location of the first CORESET and which set of search spaces the first group CSS belongs to.
In one example, the second signaling is a RAR signaling, a Msg.4 signaling or a RRC signaling. In one example, the second signaling comprises second information of at least one of a time-frequency location of the second CORESET and which set of search spaces the second group CSS belongs to.
In one example, the first signaling and the third signaling is a same signaling or different signalings.
In one example, the BS transmits the first signaling for configuring the first group CSS on the first CORESET for a third UE, to the third UE, and transmits the first DCI via the first group CSS to the third UE. That is, the first UE and the third UE can be seen as the UEs in a same UE group. The BS configures the UEs in the same UE group to receive the same DCI(s) via the same group CSS on the same CORESET.
In one example, the BS transmits the second signaling for configuring the second group CSS on the second CORESET for a fourth UE, to the fourth UE. The BS transmits the third signaling for configuring the first group CSS on the first CORESET for the fourth UE, to the fourth UE. The BS transmits the first DCI to the fourth UE via the first group CSS. The BS transmits the second DCI to the fourth UE via the second group CSS. That is, the second UE and the fourth UE can be seen as the UEs in a same UE group. The BS configures the UEs in the same UE group to receive the same DCI(s) via the same group CSS on the same CORESET.
Step 700: Start.
Step 702: Receive a signaling for configuring a group CSS on a CORESET, from a BS.
Step 704: Determine a time-frequency location of the CORESET and the group CSS on the CORESET, according to the signaling.
Step 706: Decode a DCI received via the group CSS from the BS, wherein the DCI comprises an UL grant or a DL assignment.
Step 708: End.
According to the process 70, the UE receives a signaling for configuring a group CSS on a CORESET, from a BS . Then, the UE determines a time-frequency location of the CORESET and the group CSS on the CORESET, according to the signaling. The UE (e.g., blindly) decodes a DCI received via the group CSS from the BS, wherein the DCI comprises an UL grant or a DL assignment.
Realization of the process 70 is not limited to the above description. The following examples may be applied to the process 70.
In one example, the signaling is a RAR signaling, a Msg.4 signaling or a RRC signaling.
In one example, the UE determines at least one of a plurality of PDCCH candidates of the group CSS, an aggregation level of the group CSS, and a number of the plurality of PDCCH candidates for the group CSS, according to the signaling.
In one example, the UE transmit a physical UL shared channel (PUSCH) to the BS according to the UL grant. The UE receives a physical DL shared channel (PDSCH) from the BS according to the DL assignment.
In one example, the group CSS is pre-allocated on the CORESET by the BS.
Those skilled in the art should readily make combinations, modifications and/or alterations on the abovementioned description and examples. For example, the skilled person easily makes new embodiments of the network based on the embodiments and examples of the UE, and makes new embodiments of the UE based on the embodiments and examples of the network. The abovementioned description, steps and/or processes including suggested steps can be realized by means that could be hardware, software, firmware (known as a combination of a hardware device and computer instructions and data that reside as read-only software on the hardware device) , an electronic system, or combination thereof. An example of the means may be the communication device 20. Any of the above processes and examples above may be compiled into the program codes 214.
To sum up, the present invention provides methods and devices for handling CSSs. The BS and the UEs are able to communicate with each other via the group CSS according to the DCI. The time-frequency resource is saved with this method. Thus, the problem in the art is solved.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.
This application claims the benefit of U.S. Provisional Applications No. 62/488,070 filed on Apr. 21, 2017, which is incorporated herein by reference.
Number | Date | Country | |
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62488070 | Apr 2017 | US |