WO2013008958A1 - Method and device for allocation of physical downlink control channel - Google Patents
Method and device for allocation of physical downlink control channel Download PDFInfo
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- WO2013008958A1 WO2013008958A1 PCT/JP2012/068540 JP2012068540W WO2013008958A1 WO 2013008958 A1 WO2013008958 A1 WO 2013008958A1 JP 2012068540 W JP2012068540 W JP 2012068540W WO 2013008958 A1 WO2013008958 A1 WO 2013008958A1
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0072—Error control for data other than payload data, e.g. control data
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L1/00—Arrangements for detecting or preventing errors in the information received
- H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
- H04L1/0045—Arrangements at the receiver end
- H04L1/0046—Code rate detection or code type detection
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/003—Arrangements for allocating sub-channels of the transmission path
- H04L5/0053—Allocation of signaling, i.e. of overhead other than pilot signals
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L5/00—Arrangements affording multiple use of the transmission path
- H04L5/0091—Signaling for the administration of the divided path
- H04L5/0094—Indication of how sub-channels of the path are allocated
Definitions
- the receiving unit is configured to receive the control channel region information over a UE specific channel and the control channel region information comprises a format indicator indicating the UE specific search space and a Downlink Control Information (DCI) format.
- the format indicator comprises a specific bit indicating the UE specific search space and the parsing unit is configured to obtain the UE specific search space based on the specific bit.
- the monitoring step comprises performing detection in the UE specific search space using the DCI format, so as to monitor the PDCCH .
- the monitoring step comprises performing blind decoding in the UE specific search space to monitor the PDCCH .
- the preset PDCCH parameter comprises information on size and location of the PDCCH .
- Fig. 4 is a schematic diagram showing a format indicator which dynamically indicates a UE specific search space according to an embodiment of the present invention
- Fig. 8 is a flowchart illustrating a method for monitoring PDCCH according to an embodiment of the present invention.
- the BS may transmit a dedicated PDCCH in the common PDCCH search space of each subframe . Similar to the PDCCH indicating paging channel resource allocation, a specific 16-bit RNTI may be predefined for the UE 10, denoted as X-RNTI .
- the parsing unit 120 calculates CRC bits for the payload bits of the dedicated PDCCH and then scrambles the resulting CRC bits with the X-RNTI of the UE 10. It is to be noted that every UE in the system monitors the common search space and performs blind decoding for the candidates of a certain PDCCH based on a common X-RNTI . This PDCC H indicates the resource allocation for a certain RRC signaling.
- the search space of the UE A in Fig. 7 includes CCEs only, in which case the entire PDCCH detection procedure as defined in the LTE/ LTE-Advanced systems can be reused as it is .
- the search space of the UE B in Fig. 7 includes both CCEs and RBs, in which case the CCEs need to be demodulated using a common reference signal while the RB s need to be demodulated using a UE specific reference signal. Then, the demodulated payloads are combined for subsequent processing.
- the search space of the UE C in Fig. 7 includes RBs only, in which case the UE only needs to perform demodulation using a UE specific reference signal.
- the UE receives control channel region information broadcasted by the BS via a certain channel.
- the UE can receive via a common channel the control channel region information including a set of UE IDs .
- the UE can blindly detect, in a common PDCCH search space defined in the LTE-Advanced system, a PDCCH indicating the control channel region information using X-RNTI .
- a PDCCH indicating the control channel region information using X-RNTI .
- the received control channel region information is parsed to obtain a search space specific to the UE. For example, it is possible to read from the content of the above PDCCH the data information on corresponding RBs, decode the read data information, and check whether the ID of the UE itself is included in the signaling based on a predefined RRC signaling format.
Abstract
A User Equipment (UE) is provided, which comprises: a receiving unit configured to receive control channel region information; a parsing unit configured to parse the received control channel region information to obtain a UE specific search space including at least one of a Physical Downlink Control Channel (PDCCH) region and an enhanced PDCCH (e-PDCCH) region; and a monitoring unit configured to monitor a PDCCH in the UE specific search space. Also provided is a method performed by a UE for monitoring a PDCCH.
Description
DESCRIPTION
TITLE OF INVENTION :
METHOD AND DEVICE FOR ALLOCATION OF PHYSICAL DOWNLINK CONTROL CHANNEL TECHNICAL FIELD
The invention relates to mobile communication technology, and more particularly, to a method and a device for allocation of Physical Downlink Control Channel (PDCCH) , applicable to a mobile communication system which performs data demodulation for a PDCCH of a User Equipment (UE) using a UE specific reference signal .
BACKGROUND ART
In 3GPP Long Term Evolution (LTE) and LTE-Advanced systems, the first few symbols of each data sub-frame are reserved for transmitting control information such as uplink/ downlink resource allocation for a UE. A PDCCH is transmitted on one or more Control Channel Elements (CCEs) each corresponding to a set of Resource Elements (REs) .
As defined in standardization documents, in the entire system, the capacity of PDCCH is closely correlated with the number of CCEs and the size of the CCE set. Since the capacity
of the PDCCH in the system is limited (e . g. , the first two symbols of a data sub-frame are reserved for transmitting the PDCCH) , a Base Station (BS) may not be able to perform further scheduling in the following situations.
1 . With the increasing use of Demodulation Reference Signal (DMRS) in the LTE-Advanced system, a Downlink Control Information (DCI) format 2C having a larger payload will be widely used. For most of scheduled UEs, at least two CCEs are necessary for reliable transmission of the DCI format 2C . If only one CCE is used, the error probability may increase due to higher code rate .
2. Coordinated Multi-Point (CoMP) transmission will be applied in the LTE-Advanced system . For a UE performing CoMP transmission at the edge of a cell, more CCEs are necessary for transmitting PDCCH information so as to ensure reliable coverage . Since the CoMP transmission cannot be performed on the PDCCH of the UE, for reliability purpose , the code rate should be lowered to ensure the desired error probability.
3. In the current standardization process for LTE-Advanced system, a research on enhanced downlink Multiple-Input Multiple-Output (MIMO) transmission in heterogeneous network is prioritized. In a typical research
scenario, a macro BS is connected via optical fiber to a number of low power Remote Radio Heads (RRHs) having the same cell ID as the BS . In this scenario, the limited PDCCH resources in the system are shared by UEs served by the macro BS and the RRH , which will necessarily lead to shortage of the PDCCH resource and thus affect the improvement of the system performance.
Therefore, enhanced PDCCH techniques need to be introduced to the LTE-Advanced system and the evolution thereof, so as to increase the PDCCH capacity and improve the spectral efficiency of the system.
In the contribution R l - 1 10461 , Ericsson, Baseline Schemes and Focus of CoMP Studies, in 3GPP TSG-RAN WG 1 #63bis meeting, Dublin, Ireland, January 201 1 , it is pointed out that further research on enhanced PDCCH technique is necessary to investigate the possibility of PDCCH transmission using UE specific signal and suggested that the R-PDCCH design for transmission of relay backhaul control information can be referenced.
In the TSG-RAN WG 1 #65 meeting, Barcelona, Spain, May 201 1 , a specific subject is separately listed for discussing the design of enhanced PDCCH (e-PDCCH) . In this meeting, a
general agreement on the design of e-PDCCH is reached, e . g. , the data modulation for the e- PDCCH can be carried out using UE specific reference signal . Also in this meeting, Samsung analyzed and compared the difference between the designs of R-PDCCH and e-PDCCH and pointed out that the relay nodes for the R-PDCCH service are typically fixed while the e-PDCCH is considered for mobile UEs . Additionally, from the perspective of physical distribution, the number of relay nodes in a macro cell is very limited while the number of UEs performing CoMP transmission or MIMO transmission may be very large . Moreover, another important difference is that a relay node cannot receive the legacy PDCCH transmission, while a UE supporting e-PDCCH may need to monitor not only the legacy PDCCH , but also the e-PDCCH newly introduced into the system, thereby obtaining corresponding control information . Further, LGE also provided two e-PDCCH design schemes. According to the first scheme, the PDCCH and the e-PDCCH are jointly designed and the UE can monitor both the PDCCH and the e-PDCCH in a particular sub-frame . However, the further detailed scheme is not described . According to the second scheme, the e-PDCCH is separately designed and, as configured via higher layer signaling, the UE can only monitor either the PDCCH or the e-PDCCH to obtain the corresponding control information. In the first scheme, a higher PDCCH transmission robustness can be achieved at the expense of the increased
number of PDCCH blind decodings. Thus, the first scheme needs to be designed in combination with a scheme for reducing the number of PDCCH blind decodings. In the second scheme, the complexity of the UE can be reduced to some extent, but the performance of e-PDCCH may be significantly degraded if the higher layer signaling is inappropriately configured or incorrectly received.
There is thus a need for a method and a device for allocation of PDCCH , capable of dynamically transmitting control signals over PDCCH or e-PDCCH without degrading the robustness of control signal transmission or increasing the complexity of UE . SUMMARY OF INVENTION
According to an aspect of the present invention, a User Equipment (UE) is provided, which comprises : a receiving unit configured to receive control channel region information; a parsing unit configured to parse the received control channel region information to obtain a UE specific search space including at least one of a Physical Downlink Control Channel (PDCCH) region and an enhanced PDCCH (e-PDCCH) region; and a monitoring unit configured to monitor a PDCCH in the UE specific search space .
Preferably, the control channel region information is received over a common channel and comprises a set of UE identifiers . The parsing unit is configured to : parse the set of UE identifiers; determine that the UE specific search space is in the e-PDCCH region if the identifier of the UE is included in the set; otherwise determine that the UE specific search space is in the PDCCH region.
Preferably, the monitoring unit is configured to perform blind decoding in the UE specific search space to monitor the PDCCH .
Preferably, the receiving unit is configured to receive the control channel region information over a UE specific channel and the control channel region information comprises a format indicator indicating the UE specific search space and a Downlink Control Information (DCI) format. The format indicator comprises a specific bit indicating the UE specific search space and the parsing unit is configured to obtain the UE specific search space based on the specific bit.
Preferably, the monitoring unit is configured to perform detection in the UE specific search space using the DCI format, so as to monitor the PDCCH .
According to another aspect of the present invention, a method performed by a User Equipment (UE) for monitoring a Physical Downlink Control Channel (PDCCH) is provided, the method comprising: receiving control channel region information; parsing the received control channel region information to obtain a UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e-PDCCH) region; and monitoring the PDCCH in the UE specific search space .
Preferably, the control channel region information is received over a common channel and comprises a set of UE identifiers. The parsing step comprises : parsing the set of UE identifiers; determining that the UE specific search space is in the e-PDCCH region if the identifier of the UE is included in the set; otherwise determining that the UE specific search space is in the PDCCH region.
Preferably, the monitoring step comprises performing blind decoding in the UE specific search space to monitor the PDCCH .
Preferably, the control channel region information is received over a UE specific channel and comprises a format indicator indicating the UE specific search space and a
Downlink Control Information (DCI) format. The format indicator comprises a specific bit indicating the UE specific search space and the parsing step comprises obtaining the UE specific search space based on the specific bit.
Preferably, the monitoring step comprises performing detection in the UE specific search space using the DCI format, so as to monitor the PDCCH . According to another aspect of the present invention, a
User Equipment (UE) is provided, which comprises : a parsing unit configured to obtain a UE specific search space based on a preset Physical Downlink Control Channel (PDCCH) parameter and a Radio Network Temporary Identifier (RNTI) of the UE, the UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e-PDCCH) region; and a monitoring unit configured to monitor a PDCCH in the UE specific search space. Preferably, the monitor unit is configured to perform blind decoding in the UE specific search space to monitor the PDCCH .
Preferably, the preset PDCCH parameter comprises information on size and location of the PDCCH .
According to another aspect of the present invention, a method performed by a User Equipment (UE) for monitoring a Physical Downlink Control Channel (PDCCH) is provided, which comprises : obtaining a UE specific search space based on a preset Physical Downlink Control Channel (PDCCH) parameter and a Radio Network Temporary Identifier (RNTI) of the UE, the UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e-PDCCH) region; and monitoring a PDCCH in the UE specific search space .
Preferably, the monitoring step comprises performing blind decoding in the UE specific search space to monitor the PDCCH . Preferably, the preset PDCCH parameter comprises information on size and location of the PDCCH .
With the present invention, a load balance in control information allocation can be achieved in a particular scenario, so as to reduce the waste of system resource due to the shortage of control channel resource. The system design according to the present invention has a low complexity and satisfies the requirements of the actual system as well as the LTE-Advanced system and the evolution thereof.
BRIEF DESCRIPTION OF DRAWINGS
The above and other features of the present invention will become more apparent from the following detailed description with reference to the figures, in which :
Fig. 1 is a block diagram showing a UE according to an embodiment of the present invention;
Fig. 2 shows a schematic diagram of a dynamic indication of a UE specific search space according to an embodiment of the present invention ;
Fig. 3 is a schematic diagram showing PDCCH candidates for a UE in a legacy PDCCH region according to an embodiment of the present invention;
Fig. 4 is a schematic diagram showing a format indicator which dynamically indicates a UE specific search space according to an embodiment of the present invention;
Fig. 5 is another schematic diagram showing a format indicator which dynamically indicates a UE specific search space according to an embodiment of the present invention;
Fig. 6 is a block diagram showing a UE according to an embodiment of the present invention;
Fig. 7 shows another schematic diagram of a dynamic indication of a UE specific search space according to an embodiment of the present invention;
Fig. 8 is a flowchart illustrating a method for monitoring PDCCH according to an embodiment of the present invention;
and
Fig. 9 is a flowchart illustrating a method for monitoring PDCCH according to an embodiment of the present invention. DESCRIPTION OF EMBODIMENTS
The principles and implementations of the present invention will become more apparent from the following description of the particular embodiments of the present invention with reference to the drawings . It should be noted that the present invention is not limited to the particular embodiments given below. Further, in the following description, details of well-known techniques unnecessary to the present invention are omitted for the sake of simplicity. The embodiments of the present invention as described below are applicable to a mobile communication system which uses a UE specific reference signal for enhanced PDCCH transmission, particularly the LTE-Advanced cellular mobile communication system and the evolution thereof. Herein, it is to be noted that the present invention is not limited to the application exemplified in the embodiments . Rather, it is applicable to other relevant communication systems, such as 5G system in the future . Fig. 1 is a block diagram showing a UE 10 according to an
embodiment of the present invention. As shown in Fig. 1 , the UE 10 according to the embodiment of the present invention comprises a receiving unit 1 10, a parsing unit 120 and a monitoring unit 130. The components of the UE 10 and their respective operations will be described in detail below.
The receiving unit 1 10 receives control channel region information broadcasted by a Base Station (BS) via a certain channel . In this embodiment, the receiving unit 1 10 receives the control channel region information via a common channel . Since the minimum time granularity for allocation of PDCCH is one sub-frame (which is defined as 1 ms in the LTE and the LTE-Advanced systems) , the minimum time granularity for broadcasting control channel region information is also one sub-frame .
After the control channel region information is correctly received, the parsing unit 120 parses the received control channel region information to obtain a UE specific search space . In accordance with the capacity for PDCCH in the system and the real-time scheduling of the UE, the PDCCH for the UE 10 can be scheduled to be transmitted in a legacy PDCCH region or in an e-PDCCH region . Fig. 2 shows a schematic diagram of a UE specific search space according to an embodiment of the present invention . As shown in Fig. 2 , the control channel
region in the system consists of two parts: one being the legacy PDCCH region and the other being the newly introduced e-PDCCH region. Fig. 3 is a schematic diagram showing a legacy PDCCH region for the UE 10 according to an embodiment of the present invention. In the legacy PDCCH region (e . g. , as defined in the LTE and the LTE-Advanced systems) , the minimum allocation unit for PDCCH is a CCE . Each CCE consists of nine Resource Element Groups (REGs) , each of which in turn includes four available resource elements (REs) . In the case of QPSK modulation, each CCE can carry 72 bits of control information. Additionally, in the legacy PDCCH region, a portion of CCEs is reserved as a common search space for transmitting resource allocation information for some common channels (e. g. , a paging channel, a dynamic broadcast channel and the like) . This common search space is monitored by every UE in a cell . Each UE has a corresponding UE specific search space . A unique CCE number can be calculated from the UE's Radio Network Temporary Identifier (RNTI) . A number of consecutive CCEs starting from the one having that CCE number constitute the search space specific to the UE .
Assuming that the CCE-n l is the start CCE of the search space specific to the UE 10 , Fig. 3 shows 16 PDCCH candidates
for the UE 10 according to the sizes of the PDCCH candidates in the CCE set. The UE 1 0 determines which of the PDCCH candidates to be the actual PDCCH for the transmission of the UE itself by blindly decoding the individual PDCCH candidates using Cyclic Redundancy Check (CRC) bits .
Referring back to Fig. 2 , in the newly introduced e-PDCCH region, since the PDCCH transmission is carried out using the UE specific reference signal, the minimum allocation unit for PDCCH is a Resource Block (RB) . There are a number of implementations for detecting PDCCH in the e-PDCCH region. For example, the blind decoding for PDCCH can be performed in a way similar to the legacy PDCCH detection by considering a RB as a CCE. Further, the UE 1 0 may be notified of relevant information such as size and location of the e-PDCCH region via higher layer signaling (RRC signaling or system broadcast channel) .
In this embodiment, the BS may transmit a dedicated PDCCH in the common PDCCH search space of each subframe . Similar to the PDCCH indicating paging channel resource allocation, a specific 16-bit RNTI may be predefined for the UE 10, denoted as X-RNTI . The parsing unit 120 calculates CRC bits for the payload bits of the dedicated PDCCH and then scrambles the resulting CRC bits with the X-RNTI of the UE 10.
It is to be noted that every UE in the system monitors the common search space and performs blind decoding for the candidates of a certain PDCCH based on a common X-RNTI . This PDCC H indicates the resource allocation for a certain RRC signaling. This certain RRC signaling includes at least a control channel region information field, which in turn includes at least a set of UE identifiers (IDs) . The UEs corresponding to the UE IDs included in the set are UEs allocated with the resource in the current sub-frame and scheduled by the BS to transmit PDCCH in the e-PDCCH region . In contrast, if a UE's ID is not included in the set, the UE is scheduled by the BS to transmit PDCCH in the legacy PDCCH region. In this case, the UE may perform blind decoding for PDCCH in the legacy PDCCH region by using the procedure defined in the LTE/ LTE-Advanced systems.
In this embodiment, the parsing unit 120 checks the set of UE IDs included in the control channel region information . If the ID of the UE 10 is included in the set, it is determined that the search space specific to the UE 10 is in the e-PDCCH region . Otherwise, it is determined that the search space specific to the UE 10 is in the PDCCH region. Afterwards, the monitoring unit 130 monitors the PDCCH in only one control channel region (either the PDCCH region or the e-PDCCH region) based on the parsing result of the parsing unit 120.
A special application of this embodiment will be given below. In order to reuse the P-RNTI defined in the LTE/ LTE-Advanced systems as the above X-RNTI , in the sub-frames having sub-frame numbers of 0 , 4 , 5 and 9 in the LTE/ LTE-Advanced systems, a PDCCH associated with the P-RNTI is transmitted in the common PDCCH search space for indicating the resource allocation for paging channels. This PDCCH is only monitored by UEs being in an idle state. In this case , in order not to affect the normal paging operation, the RRC signaling for PDCCH indication associated with the P-RNTI on the sub-frames having sub-frame numbers of 0 , 4 , 5 and 9 in the system needs to be redefined . The RRC signaling includes at least two fields . The first field is a paging information field which has the same definition as the paging information defined in 3GPP TS 36.33 1 V I O .0.0 and is used for paging one or more UEs in the idle state . The second field is the above described control channel region information field which includes at least a set of UE IDs .
According to another embodiment, in order to further reduce the complexity of the UE 10 , a Format Indicator (FI) can be introduced to reduce the number of blind decodings performed by the UE 10. In this embodiment, the receiving unit 1 10 receives, via a UE specific channel, the control channel
region information including a FI indicating the UE specific search space and a Downlink Control Information (DCI) format. In particular, a FI composed of a fixed number of bits (e .g. , 3 bits) is coded at a fixed code rate and then mapped, along with a UE specific CRC bit, onto a particular CCE in the UE specific search space in the control channel PDCCH region of the UE 10. Depending on the specific system design and the actual transmission code rate, the above coded bits can be mapped onto the entire CCE or onto a part of RE resources of the CCE. In the latter case, the remaining RE resources of the CCE can be used to transmit the corresponding DCI information .
The FI may include two portions of information, one being information on the control channel region where the DCI is located, the other being DCI format information. For example , a 3-bit FI can indicate 8 states (000 - 1 1 1 ) , in which four states (000 -0 1 1 ) can indicate at maximum four different DCI formats for the control channel PDCCH region and the remaining four states ( 100- 1 1 1 ) can indicate at maximum four different DCI formats for the control channel e-PDCCH region .
Fig. 4 is a schematic diagram showing a format indicator and a UE specific search space according to an embodiment of the present invention . As shown in Fig. 4 , assuming that, in the control channel PDCCH region, the search space for the UE is
CCE-nO ~ CCE-n7, according to the scheduling by a BS , the FI bits are mapped onto the first CCE (i. e . , CCE-nO) in the search space of the UE. A CCE consists of 9 REGs. Assuming the FI bits are mapped onto the first 5 REGs in the CCE, the FI bits indicate that the control channel region of the UE is the PDCCH region and the DCI format is a particular DCI format X. In this way, the UE 1 0 can monitor using the DCI format X at individual set levels based on the FI information. For example, assuming that the set level is 4 , data modulation can be performed on the remaining REGs of the CCE-nO as well as the CCE-n 1 ~CCE-n3 using a common reference signal. Then , the modulated payload can be verified by means of CRC .
Fig. 5 is another schematic diagram showing a format indicator and a UE specific search space according to an embodiment of the present invention . As shown in Fig. 5 , assuming that, in the control channel PDCCH region, the search space for the UE is CCE-nO~CCE-n7, according to the scheduling by a BS , the FI bits are mapped onto the first CCE (i. e . , CCE-nO) in the search space of the UE . A CCE consists of 9 REGs. Assuming the FI bits are mapped onto the first 5 REGs in the CCE, the FI bits indicate that the control channel region of the UE is the e-PDCCH region and the DCI format is a particular DCI format X. In this way, the UE 10 can monitor using the DCI format X at individual set levels based on the FI
information. For example, assuming that the set level is 4 , data modulation can be performed on the remaining REGs of the CCE-nO using a common reference signal and on the RB-nO~RB-n2 using a UE specific reference signal. Then, the modulated payload can be verified by means of CRC .
In this embodiment, by indicating to the currently scheduled UE its DCI format and the control information region where its DCI format is located, it is possible to reduce the number of blind decodings performed by the UE 10 , thereby reducing the complexity of the UE 10.
Fig. 6 is a block diagram showing a UE 60 according to an embodiment of the present invention. As shown in Fig. 6, the UE 60 includes a parsing unit 620 and a monitoring unit 630. The components of the UE 60 and their respective operations will be described in detail below.
The parsing unit 620 obtains a UE specific search space based on a preset Physical Downlink Control Channel (PDCCH) parameter and a Radio Network Temporary Identifier (RNTI) of the UE. In this embodiment, the legacy PDCCH region is extended to the e-PDCCH region . In other words, the e-PDCCH can be considered as an extension of the legacy PDCCH region . In the legacy PDCCH region, the minimum unit for allocation of
PDCCH is a CCE on which the data is demodulated using a Common Reference Signal (CRS) . On the other hand, in the e-PDCCH region, the minimum unit for allocation of PDCCH is a RB on which the data is demodulated using a UE specific reference signal. The UE 60 can obtain the number of CCEs in the PDCCH region in each sub-frame based on PCFICH and the number of PHICH symbols. Herein, the PCFICH indicates the number of OFDM symbols in the PDCCH region and the number of PHICH symbols is obtained from PBCH . Further, the UE 60 may be notified of the size and location of the e-PDCCH region via a higher layer signaling or a broadcast channel .
The monitoring unit 630 monitors the PDCCH in the search space specific to the UE 60. Fig. 7 shows a schematic diagram of a UE specific search space according to an embodiment of the present invention . As shown in Fig. 7, the entire PDCCH region of the system consists of a legacy PDCCH region and an e- PDCCH region which are numbered logically in a unified manner. Here, the CCE0-CCE 15 are defined as a common PDCCH search space in which the resource allocation information for some common information is transmitted. The same algorithm as that used in the LTE/ LTE-Advanced systems can be applied in which the sum of total number of CCEs and the total number of RBs is defined as the total number of CCEs in the LTE/ LTE-Advanced systems .
The parsing unit 620 can calculate a unique search space start position based on the total number of CCEs and the RNTI of the UE 60. For each allocated search space, the monitoring unit 630 will monitor (by means of blind decoding) the possible PDCCH payload for every candidate . Herein, a search space means a series of CCEs and/ or a set of RBs.
In view of the fact that the search spaces of different UEs may have different start positions and different sizes, there are the following three situations. 1 ) The search space of the UE A in Fig. 7 includes CCEs only, in which case the entire PDCCH detection procedure as defined in the LTE/ LTE-Advanced systems can be reused as it is . 2) The search space of the UE B in Fig. 7 includes both CCEs and RBs, in which case the CCEs need to be demodulated using a common reference signal while the RB s need to be demodulated using a UE specific reference signal. Then, the demodulated payloads are combined for subsequent processing. 3) The search space of the UE C in Fig. 7 includes RBs only, in which case the UE only needs to perform demodulation using a UE specific reference signal.
In this embodiment, the UE 60 is pre-configured such that the UE 60 can monitor the PDCCH without receiving additional information from the BS , thereby reducing the communication
between the UE and the BS .
Fig. 8 is a flowchart illustrating a method 80 for monitoring PDCCH according to an embodiment of the present invention . This method can be performed at the above described UE according to the present invention. As shown in Fig.8 , the method starts with step S8 10.
At step S820, the UE receives control channel region information broadcasted by the BS via a certain channel. For example , the UE can receive via a common channel the control channel region information including a set of UE IDs . In this way, the UE can blindly detect, in a common PDCCH search space defined in the LTE-Advanced system, a PDCCH indicating the control channel region information using X-RNTI . Alternatively, if such PDCCH is not detected, it is determined that no resource is allocated to the UE in this sub-frame and the method 80 ends. If the above PDCCH is detected, at step S830, the received control channel region information is parsed to obtain a search space specific to the UE. For example, it is possible to read from the content of the above PDCCH the data information on corresponding RBs, decode the read data information, and check whether the ID of the UE itself is included in the
signaling based on a predefined RRC signaling format.
At step S840, the UE monitors the PDCCH in the UE specific search space . For example, if the RRC signaling includes the ID of the UE itself, the UE will perform a PDCCH blind decoding in a specified e-PDCCH region . On the other hand, if the RRC signaling does not include the ID of the UE itself, the UE will perform a PDCCH blind decoding in the legacy PDCCH region.
Alternatively, if the UE fails to detect the PDCCH for the UE itself in the specified control channel region, it is determined that no resource is allocated to the UE in this sub-frame and the method 80 ends . On the other hand, if the UE detects the PDCCH for the UE itself in the specified control channel region , the PDSCH content is read on the corresponding RBs based on the content of the PDCCH .
Finally, the method 80 ends at step S850.
Alternatively, the control signal region information can be received via a UE specific channel and includes a FI indicating the UE specific search space and a DCI format. This FI includes a specific bit for indicating the UE specific search space . In this case, the UE specific search space can be obtained based on the
specific bit and the PDCCH can be monitored by detecting in the UE specific search space using the DCI format (see Figs . 4 and 5) . Fig. 9 is a flowchart illustrating a method 90 for monitoring PDCCH according to an embodiment of the present invention. This method can be performed at the above described UE according to the present invention. As shown in Fig.9 , the method starts with step S9 10.
At step S920, the UE specific search space can be obtained based on a preset PDCCH parameter and the UE's RNTI . The present PDDCH parameter includes information on size and location of the PDCCH . For example, a unique search space start position can be calculated based on the total number of CCEs in the system and the RNTI of the UE. For each allocated search space, the possible PDCCH payload on every candidate can be monitored (by means of blind decoding) . Next, at step S930 , the PDCCH is monitored in the UE specific search space . In view of the fact that the search spaces of different UEs may have different start positions and different sizes, there are the following three situations . 1 ) If the search space of the UE includes CCEs only, the entire PDCCH detection procedure as defined in the LTE / LTE-Advanced
systems can be reused as it is . 2) If the search space of the UE includes both CCEs and RB s, the CCEs need to be demodulated using a common reference signal while the RBs need to be demodulated using a UE specific reference signal. Then, the demodulated payloads are combined for subsequent processing. 3) If the search space of the UE includes RBs only, the UE only needs to perform demodulation using a UE specific reference signal. Finally, the method 90 ends at step S940.
With the above approaches for monitoring PDCCH , the BS can dynamically allocate PDCCH to the UE in the control channel PDCCH region or the control channel e-PDCCH region, such that a load balance in control information allocation can be achieved in a particular scenario, thereby reducing the waste of system resource due to the shortage of control channel resource . The system design according to the present invention has a low complexity and satisfies the requirements of the actual system as well as the LTE-Advanced system and the evolution thereof.
The present invention has been described above with reference to the preferred embodiments thereof. It should be understood that various modifications, alternations and
additions can be made by those skilled in the art without departing from the spirits and scope of the present invention. Therefore, the scope of the present invention is not limited to the above particular embodiments but only defined by the claims as attached and the equivalents thereof.
Claims
1 . A User Equipment (UE) , comprising:
-a receiving unit configured to receive control channel region information;
-a parsing unit configured to parse the received control channel region information to obtain a UE specific search space including at least one of a Physical Downlink Control Channel (PDCCH) region and an enhanced PDCCH (e-PDCCH) region; and
-a monitoring unit configured to monitor a PDCCH in the UE specific search space .
2. The UE according to claim 1 , wherein the receiving unit is configured to receive the control channel region information over a common channel and the control channel region information comprises a set of UE identifiers .
3. The UE according to claim 2 , wherein the parsing unit is configured to :
parse the set of UE identifiers ;
determine that the UE specific search space is in the e-PDCCH region if the identifier of the UE is included in the set; otherwise determine that the UE specific search space is in the PDCCH region.
4. The UE according to claim 3 , wherein the monitoring unit is configured to perform blind decoding in the UE specific search space to monitor the PDCCH .
5. The UE according to claim 1 , wherein the receiving unit is configured to receive the control channel region information over a UE specific channel and the control channel region information comprises a format indicator indicating the UE specific search space and a Downlink Control Information (DCI) format.
6. The UE according to claim 5, wherein the format indicator comprises a specific bit indicating the UE specific search space and the parsing unit is configured to obtain the UE specific search space based on the specific bit.
7. The UE according to claim 6, wherein the monitoring unit is configured to perform detection in the UE specific search space using the DCI format, so as to monitor the PDCCH .
8. A method performed by a User Equipment (UE) for monitoring a Physical Downlink Control Channel (PDCCH) , the method comprising:
-receiving control channel region information; -parsing the received control channel region information to obtain a UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e- PDCCH) region; and
-monitoring the PDCCH in the UE specific search space.
9. The method according to claim 8, wherein the control channel region information is received over a common channel and comprises a set of UE identifiers .
10. The method according to claim 9 , wherein the parsing step comprises:
parsing the set of UE identifiers;
determining that the UE specific search space is in the e-PDCCH region if the identifier of the UE is included in the set; otherwise determining that the UE specific search space is in the PDCCH region .
1 1 . The method according to claim 10, wherein the monitoring step comprises performing blind decoding in the UE specific search space to monitor the PDCCH .
12. The method according to claim 8 , wherein the control channel region information is received over a UE specific channel and comprises a format indicator indicating the UE specific search space and a Downlink Control Information (DCI) format.
13. The method according to claim 12 , wherein the format indicator comprises a specific bit indicating the UE specific search space and the parsing step comprises obtaining the UE specific search space based on the specific bit.
14. The method according to claim 13 , wherein the monitoring step comprises performing detection in the UE specific search space using the DCI format, so as to monitor the PDCCH .
1 5. A User Equipment (UE) , comprising:
-a parsing unit configured to obtain a UE specific search space based on a preset Physical Downlink Control Channel (PDCCH) parameter and a Radio Network Temporary Identifier (RNTI) of the UE, the UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e-PDCCH) region; and
-a monitoring unit configured to monitor a PDCCH in the
UE specific search space .
16. The UE according to claim 15 , wherein the monitor unit is configured to perform blind decoding in the UE specific search space to monitor the PDCCH .
17. The UE according to claim 1 5, wherein the preset PDCCH parameter comprises information on size and location of the PDCCH .
18. A method performed by a User Equipment (UE) for monitoring a Physical Downlink Control Channel (PDCCH) , the method comprising:
-obtaining a UE specific search space based on a preset Physical Downlink Control Channel (PDCCH) parameter and a Radio Network Temporary Identifier (RNTI) of the UE, the UE specific search space including at least one of a PDCCH region and an enhanced PDCCH (e-PDCCH) region; and
-monitoring a PDCCH in the UE specific search space .
19. The method according to claim 18 , wherein the monitoring step comprises performing blind decoding in the UE specific search space to monitor the PDCCH .
20. The method according to claim 18 , wherein the preset
PDCCH parameter comprises information on size and location of the PDCCH .
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| CN2011101958936A CN102883368A (en) | 2011-07-13 | 2011-07-13 | Distribution method and equipment of physical downlink control channel |
| CN201110195893.6 | 2011-07-13 |
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| WO2013008958A1 true WO2013008958A1 (en) | 2013-01-17 |
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| WO2017091384A1 (en) * | 2015-11-23 | 2017-06-01 | Qualcomm Incorporated | Techniques for multiplexing or cascading control information and data within a transmission time interval |
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| CN102883368A (en) | 2013-01-16 |
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