The present invention relates to inter-band carrier aggregation (CA) and more particularly relates to addressing User Equipment (UE) behavior during overlapped uplink-downlink sub frames of different component carriers in inter-band CA with cell specific TDD configuration.
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and LTE-Advanced systems, the required spectral efficiency and requested peak data rates for downlink (DL) and uplink (UL) can be achieved with Carrier Aggregation (CA). CA is one of the promising technologies that enhance the data throughput using multiple component carriers (CCs). It is a highly demanded feature from a network operator perspective, since it also enables the aggregation of different frequency spectrum fragments and offers a way out of the spectrum crunch. CA aggregates multiple CCs and jointly uses them for transmission to/from a single User Equipment (UE). CA is supported in both Frequency Division Duplex (FDD) and Time Division Duplex (TDD) operation modes. LTE-Advanced cellular system specified by 3GPP supports two types of CA techniques, namely, intra-band CA and inter-band CA.
In inter-band CA, it is possible to support different uplink-downlink configurations on different carriers on different frequency bands which are far apart. With cell specific TDD configuration on each CC even though there is a possibility of overlap of DL-UL sub frames of involved component carriers; the UE behavior for monitoring Physical Downlink Control Channels (PDCCH) sub frames during the DL-UL overlap depends on UE implementation.
The full duplex UE implementation handles the overlap situation by supporting simultaneous reception (DL) and transmission (UL) in the respective configured CC. In half duplex UE implementations, where the UE is not capable of simultaneous reception and transmission in overlapped DL-UL sub frames of the respective configured CC on different frequency bands, the UE behavior has to be specified.
Existing methods such as follow PCell, union and intersection specify UE behavior for monitoring PDCCH and handling the Discontinuous Reception (DRX) timers related to the PDCCH sub frames only for full duplex UE implementation. These existing methods limit only to UE implementations capable of simultaneous reception and transmission in overlapped DL-UL sub frames. Also, existing methods are ambiguous to specify additional details required by the UE when the UE implementations do not support simultaneous transmission and reception.
In the light of above discussion, a method and system to define UE behavior to monitor PDCCH sub frame and handling the DRX timers for UE's not capable of simultaneous reception and transmission in overlapped DL-UL sub frames in inter-band carrier aggregation with cell specific TDD configuration is appreciated.
The principal object of the embodiments herein is provide a method and system that define User Equipment (UE) behavior to monitor PDCCH sub frame, in which the UE is capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames in inter-band Carrier Aggregation (CA) with cell specific Time Division Duplex (TDD) configuration.
Another object of the invention is to provide a method to address the UE behavior for handling Discontinuous Reception (DRX) timers when UE is not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames in inter-band carrier aggregation with cell specific TDD configuration.
Accordingly the invention provides a method for handling behavior of User Equipment (UE) which is capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames during inter-band carrier aggregation of configured component carriers in a Time Division Duplex (TDD) mode. The method comprises allowing the UE to monitor PDCCH sub frame of the configured component carriers when DL sub frame of respective component carrier is not overlapping with corresponding UL sub frame of at least one component carrier from the configured component carriers. Further the method allows the UE to transmit on the UL sub frame of the configured component carriers when the UL sub frame of respective component carrier is not overlapping with corresponding DL sub frame of at least one component carrier from the configured component carriers.
Accordingly the invention provides a configuration and signaling from network for handling behavior of User Equipment (UE) which is capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames during inter-band carrier aggregation of configured component carriers in a Time Division Duplex (TDD) mode. The network is configured to allow the UE to monitor PDCCH sub frame of the configured component carriers when DL sub frame of respective component carriers is not overlapping with corresponding UL sub frame of at least one component carrier from the configured component carriers. Further the network is configured to allow the UE to transmit on the UL sub frame of the component carriers when the UL sub frame of respective component carrier is not overlapping with corresponding DL sub frame of at least one component carrier from the configured component carriers.
Accordingly the invention provides a User Equipment (UE) capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames during inter-band carrier aggregation of configured component carriers in a Time Division Duplex (TDD) mode. The UE comprises an integrated circuit. Further the integrated circuit comprises at least one processor and at least one memory. The memory comprises a computer program code within the circuit. At least one memory and the computer program code with the at least one processor cause the UE to monitor PDCCH sub frame of the configured component carriers when DL sub frame of respective component carriers is not overlapping with corresponding UL sub frame of at least one component carrier from the configured component carriers. Further the UE is configured to transmit on the UL sub frame of the component carriers when UL sub frame of respective component carriers is not overlapping with corresponding DL sub frame of at least one component carrier from the configured component carriers.
These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
The present invention is capable of defining User Equipment (UE) behavior to monitor PDCCH sub frame, in which the UE is capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames in inter-band Carrier Aggregation (CA) with cell specific Time Division Duplex (TDD) configuration.
This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The embodiments herein achieve a method and system to handle behavior of User Equipment (UE), where the UE is capable of carrier aggregation but not capable of simultaneous reception and transmission in overlapped Downlink (DL)-Uplink (UL) sub frames during inter-band carrier aggregation with cell specific TDD configuration. The method specifies whether the UE is allowed or not allowed to monitor the PDCCH sub frames during overlap of DL-UL sub frames by signaling the UE with a resultant TDD configuration that is applicable to the PCell and one or more SCells. The method also addresses handling of the DRX timers by defining the active time for common DRX operation by the UE for all component carriers.
In an embodiment, the network signals the resultant TDD configuration through Radio Resource Control (RRC) signaling either in System Information broadcast or dedicated RRC message or through physical layer signaling.
The method also enhances the procedures and UE behavior specified in 3GPP TS 36.321, Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC); Protocol specification.
Referring now to the drawings, and more particularly to
In an embodiment, the UE may also comprise of several other modules which fall within the scope of the invention known to a person with ordinary skill in the art.
The upper part of
The lower part of
In accordance with LTE Release 10 specification (TS 36.331) in context of Carrier Aggregation (CA), the primary cell (PCell) is the cell operating on the primary frequency, in which the UE 100 either performs the initial connection establishment procedure or initiates the connection re-establishment procedure, or is the cell indicated as the primary cell in the handover procedure. The secondary cell (SCell) is the cell operating on a secondary frequency, which may be configured once an RRC connection is established in the PCell, and the SCell may be used to provide additional radio resources. For the UE 100 in RRC_CONNECTED not configured with CA there is only one serving cell comprising of the primary cell. For the UE 100 in RRC_CONNECTED configured with CA the term ‘serving cells’ is used to denote the set of one or more configured carriers comprising of one primary cell and all other secondary cells.
The ten sub frames in each of PCell and SCell consists either RX (reception sub frames) relating to downlink (DL) operation or TX (transmission sub frames) relating to uplink (UL) operation and one special sub frame. As depicted in figure, both PCell and SCell have component carriers that follow different (cell specific) LTE TDD configuration. In such scenario of CA operation there exist DL-UL overlap of sub frames of respective component carrier and the UE 100 behavior for PDCCH monitoring and handling DRX timers has to be specified. For example, sub frame #4 of component carrier #1 of SCell indicates RX operation while the corresponding sub frame #4 of component carrier#2 of PCell indicates TX operation. The UE 100 should be specified (addressed) when it is allowed to monitor PDCCH (to find next PDCCH sub frame) and the way UE 100 has to handle the DRX timers.
Common DRX configuration and common DRX operation in LTE Release 10 specification TS 36.300:
In order to enable reasonable UE battery consumption, DRX in Evolved Universal Terrestrial Radio Access network (E-UTRAN) is characterized as Per UE mechanism (as opposed to per radio bearer).
In CA operation, whenever a UE is configured with only one serving cell (i.e. PCell) Rel-89 DRX applies. In other cases, the same DRX operation applies to all configured and activated serving cells (i.e. identical active time for PDCCH monitoring).
The specification above infers that DRX configuration is common across all component carriers and common DRX operation is applied across all configured and activated component carriers.
Handling of DRX timers in LTE Release 10 specification (TS 36.321) states the following definitions:
PDCCH-subframe: Refers to a subframe with PDCCH or, for an RN with R-PDCCH configured and not suspended, to a subframe with R-PDCCH. For Frequency Division Duplex (FDD) UE operation, this represents any subframe; for TDD, only downlink subframes and subframes including DwPTS. For RNs with an RN subframe configuration configured and not suspended, in its communication with the E-UTRAN, this represents all downlink subframes configured for RN communication with the E-UTRAN.
Active Time: Time related to DRX operation, during which the UE monitors the PDCCH, as defined in subclause 5.7 in of 3GPP specification TS 36.321.
DRX-InactivityTimer: Specifies the number of consecutive PDCCH-subframe(s) after successfully decoding a PDCCH indicating an initial UL or DL user data transmission for this UE.
DRX-RetransmissionTimer: Specifies the maximum number of consecutive PDCCH-subframe(s) for as soon as a DL retransmission is expected by the UE.
onDurationtimer: Specifies the number of consecutive PDCCH-subframe(s) at the beginning of a DRX Cycle.
In
The UE 100 implementation which is not capable of simultaneous reception and transmission (half duplex TDD UE implementation) in overlapped DL-UL sub frames can monitor PDCCH in PDCCH-sub frames identified by method 3 (intersection). When UE 100 adopts method 1 or method 2, the UE 100 behavior for PDCCH monitoring in the shaded PDCCH-sub frames (sub frame #8 in method 1 and sub frame #4, #5 and #8 in method 2 needs to be further specified. The network (eNB) additionally needs to inform the UE whether transmission or reception is supported in overlapped sub frames as half duplex capable UE 100 can perform either of transmission or reception operation at given time instant. The existing methods fail to specify this further behavior of UE 100 and cannot be used when the UE 100 is not capable of simultaneous reception and transmission (half duplex TDD UE implementation).
With the existing methods the half duplex UE can perform usual PDCCH monitoring in rest of the identified PDCCH-sub frames that do not have DL-UL overlap in the respective component carriers.
The method disclosed provides plurality of embodiments to address the UE's 100 behavior during DL-UL overlapped sub frames when the UE 100 is not capable of simultaneous reception and transmission (half duplex TDD UE implementation) in respective component carrier. The method specifies whether the UE 100 has to perform transmission or reception during the identified DL-UL overlap through the network configuration.
In one embodiment, the method enables the UE 100 to behave as specified by existing method-1 (follow PCell) and in addition specifies conditions the UE 100 should check to decide whether to transmit or not to transmit during identified DL-UL overlap. For example, referring to method -1 (Follow PCell) of
All sub frames of cell specific TDD configuration of each component carrier are allowed sub frames, except the overlapped sub frames where allowed sub frame on one component carrier correspond to not allowed sub frame on another component carrier based on network configuration.
In an embodiment, the network configuration is semi-static through RRC signaling or is dynamic through physical layer signaling.
In an embodiment, the UE 100 behavior is specified as follows:
In case of inter-band TDD CA, both half duplex and full duplex UE implementation should consider the union of PDCCH sub frames of configured component carriers for PDCCH sub frame identification (irrespective of whether the component carrier is active or not active).
In an embodiment, the UE 100 behavior is specified as follows:
In case of inter-band TDD CA, UE implementation not capable of simultaneous reception and transmission in overlapped DL-UL sub frames of respective component carriers on different bands, the UE should not monitor the PDCCH-sub frame of a component carrier if uplink transmission is scheduled in the corresponding UL sub frame of the other component carrier.
In an embodiment, the UE 100 behavior is specified as follows:
In case of inter-band TDD CA, UE implementation not capable of simultaneous reception and transmission in overlapped DL-UL sub frames of respective component carriers on different bands, UE should not transmit on the UL sub frame of a component carrier if DL assignment is scheduled in the corresponding DL sub frame of the other component carrier.
In an embodiment, all sub frames of cell specific TDD configuration of each component carrier are allowed sub frames, except the overlapped sub frames where allowed sub frame on one component carrier correspond to not allowed sub frame on another component carrier based on network configuration.
According to LTE Release 10 specification (TS 36.331), the SystemInformationBlockType1 (SIB1) contains information about the TDD configuration. Normally, the UE 100 follows the TDD configuration indicated by the PCell. According to LTE Release 10 specification (TS 36.300), when CA is deployed frame timing, System Frame Number (SFN) and TDD-Configuration are aligned across cells that can be aggregated. The TDD CA capable UE 100 has the same TDD configuration for all serving cells. This is true for intra-band CA while for inter-band CA, UE 100 could be configured with cell specific TDD configuration for each component carrier. The SIB1 of each component carrier can signal the cell specific TDD configuration. However, for UE implementation not capable of simultaneous reception and transmission in overlapped DL-UL sub frames during inter-band CA, the allowed/not allowed sub frame configuration needs to be signaled to the UE 100.
In an embodiment, the network (eNB) signals the resultant TDD configuration to the UE 100 either through dedicated signaling or dynamic physical layer signaling so that UE is aware of allowed/not allowed sub frames from the cell specific TDD configuration of each component carrier signaled in SIB1.
In another embodiment the network (eNB) signals the resultant TDD configuration through the RRC Connection Reconfiguration message when it configures the SCell(s).
In an embodiment, the resultant TDD configuration is from among the existing 3GPP pre-defined TDD configurations specified in said 3GPP specification TS 36.211.
In an embodiment, the resultant TDD configuration is other than the existing 3GPP pre-defined TDD configurations specified in said 3GPP specification TS 36.211.
In an embodiment, the resultant TDD configuration of the configured component carriers is same as the TDD configuration of the PCell.
In an embodiment, the method also specifies expected UE behavior while handling allowed PDCCH-sub frames to be considered for DRX timers based on the signaled resultant TDD configuration. The method ascertains the UE 100 behavior for handling DRX timers when DRX cycle is configured in the UE 100. The method specifies the UE 100 to monitor the PDCCH and consider the monitored PDCCH sub frame as part of active time of said DRX cycle if the sub frame is not part of configured measurement gap and is not configured as UL sub frame in the resultant TDD configuration. Thereafter with the sub frame considered as PDCCH sub frame, the method specifies the UE 100 to start Hybrid Automatic Repeat Request (HARQ) Round Trip Time (RTT) timer for the HARQ process and stop DRX retransmission timer for the HARQ process.
The method further allows the UE 100 to start DRX-Inactivity timer if the monitored PDCCH sub frame indicates either a new DL assignment and/or new grant for UL transmission.
In an embodiment, the method specifies expected UE behavior while handling not allowed (forbidden) PDCCH-sub frames to be considered for DRX timers based on the signaled resultant TDD configuration. The method ascertains the UE 100 behavior for handling DRX timers when DRX cycle is configured in UE. The method forbids the UE 100 to monitor the PDCCH and forbids the UE to consider the PDCCH sub frame as part of active time of said DRX cycle if the (not allowed PDCCH) sub frame is not part of configured measurement gap and if the (not allowed) sub frame is configured as UL sub frame in the resultant TDD configuration. The method further specifies the UE not to increment the onDurationTimer, if the onDurationTimer is running during the monitoring of PDCCH sub frame. Further, the method forbids incrementing the DRX-Inactivity timer during the not allowed (forbidden) PDCCH sub frame.
Thereafter, the method forbids the UE 100 to increment DRX retransmission timer for the HARQ process.
The embodiments disclosed herein can be implemented through at least one software program running on at least one hardware device and performing network management functions to control the elements. The elements shown in
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Number | Date | Country | Kind |
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973/CHE/2012 | Mar 2012 | IN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/KR2013/002095 | 3/15/2013 | WO | 00 |