ltePDCCHSearch
PDCCH downlink control information search
Description
[
recovers
downlink control information (DCI) message structures, dcistr
,dcibits
]
= ltePDCCHSearch(enb
,chs
,softbits
)dcistr
,
and corresponding vectors of DCI message bits, dcibits
,
after blind decoding the multiplexed physical downlink control channels
(PDCCHs) within the control region given by the softbits
input
vector, cell-wide configuration, enb
, and UE-specific
channel configuration, chs
. For more information,
see PDCCH Search Processing.
Examples
Get DCI Message Structure and Bits
Extract and decode the PDCCH symbols from the control region of a subframe grid created by the DL waveform generator, lteRMCDLTool
. Use the blind search function, ltePDCCHSearch
, to search the common and UE-specific spaces by demasking all PDCCH candidates with the configured RNTI.
Use a waveform generator to create a full subframe grid containing a reference PDSCH and associated DCI in UE-specific search space. Extract and decode all the PDCCH multiplex (control region) bits.
rmc = lteRMCDL('R.0');
[~,txGrid] = lteRMCDLTool(rmc,[1;0;0;1]);
pdcchSymbols = txGrid(ltePDCCHIndices(rmc));
rxPdcchBits = ltePDCCHDecode(rmc,pdcchSymbols);
Configure the UE-specific parameters that affect the DCI message lengths to match those of the reference UE.
ueConfig.RNTI = rmc.PDSCH.RNTI; ueConfig.EnableCarrierIndication = 'Off'; ueConfig.EnableSRSRequest = 'Off'; ueConfig.EnableMultipleCSIRequest = 'Off'; ueConfig.NTxAnts = 1;
Use PDCCH blind search to find the DCI that schedules the PDSCH. Extract and display first DCI message structure from the search list. Compare the format of the DCI message returned in the previous step with the format used by the waveform generator.
[rxDCI,rxDCIBits] = ltePDCCHSearch(rmc,ueConfig,rxPdcchBits); decDCI = rxDCI{1}
decDCI = struct with fields:
DCIFormat: 'Format1'
CIF: 0
AllocationType: 1
Allocation: [1x1 struct]
ModCoding: 14
HARQNo: 0
NewData: 1
RV: 0
TPCPUCCH: 0
TDDIndex: 0
HARQACKResOffset: 0
decDCIFormat = decDCI.DCIFormat
decDCIFormat = 'Format1'
txDCIFormat = rmc.PDSCH.DCIFormat
txDCIFormat = 'Format1'
Get Two DCI Messages
Map a pair of format 0 uplink and format 1A downlink grants into a UE-specific search space in the PDCCH multiplex. Use the blind search function to recover them. Because the search space is UE-specific, you can extend the messages to include the Release 10 SRS request field and a 2-bit CSI request field for the format 0 DCI. For simplicity, the example does not include any PDCCH channel processing steps.
Create a vector containing the control region PDCCH multiplex bits.
enb = lteRMCDL('R.0');
pdcchinfo = ltePDCCHInfo(enb);
pdcchmux = zeros(1,pdcchinfo.MTot);
Configure the UE-specific parameters to control the DCI and encoding.
chs = struct('RNTI',1,'PDCCHFormat',2); chs.ControlChannelType = 'PDCCH'; chs.SearchSpace = 'UESpecific'; chs.EnableCarrierIndication = 'Off'; chs.EnableSRSRequest = 'On'; chs.EnableMultipleCSIRequest = 'On'; chs.NTxAnts = 1;
List the formats to create and get the UE-specific search space candidate locations in the PDCCH multiplex.
formats = {'Format0','Format1A'}; candidates = ltePDCCHSpace(enb,chs);
For each DCI format, create the DCI info bits and encode them for PDCCH mapping. Demonstrate setting of the ModCoding
field to a nondefault value. Select a candidate to carry the target PDCCH.
for f = 1:length(formats) dciin = struct('DCIFormat',formats{f},'ModCoding',f); [dci,dcibits] = lteDCI(enb,chs,dciin); pdcch = lteDCIEncode(chs,dcibits); pdcchmux(candidates(f,1):candidates(f,2)) = pdcch; end
Search PDCCH multiplex bits for any DCI messages directed at UE RNTI.
rxPdcchBits = 2*pdcchmux - 1; rxDCI = ltePDCCHSearch(enb,chs,rxPdcchBits)
rxDCI=1×2 cell array
{1x1 struct} {1x1 struct}
rxDCI{:}
ans = struct with fields:
DCIFormat: 'Format1A'
CIF: 0
AllocationType: 0
Allocation: [1x1 struct]
ModCoding: 2
HARQNo: 0
NewData: 0
RV: 0
TPCPUCCH: 0
TDDIndex: 0
SRSRequest: 0
HARQACKResOffset: 0
ans = struct with fields:
DCIFormat: 'Format0'
CIF: 0
FreqHopping: 0
Allocation: [1x1 struct]
ModCoding: 1
NewData: 0
TPC: 0
CShiftDMRS: 0
TDDIndex: 0
CSIRequest: 0
SRSRequest: 0
AllocationType: 0
Input Arguments
enb
— Cell-wide settings
structure
Cell-wide settings, specified as a structure with these fields.
Parameter Field | Required or Optional | Values | Description |
---|---|---|---|
NDLRB | Required | Scalar integer from 6 to 110 | Number of downlink resource blocks () For information on link bandwidth assignment, see Specifying Number of Resource Blocks. |
NULRB | Required | Scalar integer from 6 to 110 | Number of uplink resource blocks. () For information on link bandwidth assignment, see Specifying Number of Resource Blocks. |
NSubframe | Required | 0 (default), nonnegative scalar integer | Subframe number |
CellRefP | Required | 1, 2, 4 | Number of cell-specific reference signal (CRS) antenna ports |
DuplexMode | Optional |
| Duplexing mode, specified as one of the following:
|
Data Types: struct
chs
— User-equipment-related channel configuration
structure
User-equipment-related (UE-related) channel configuration, specified as a structure containing the following UE-specific fields.
RNTI
— Radio network temporary identifier
1 (default) | numeric scalar
Radio network temporary identifier value, specified as a numeric scalar.
Data Types: double
EnableCarrierIndication
— Option to enable carrier indication
'Off'
(default) | 'On'
| optional
Option to enable carrier indication UE configuration, specified
as 'Off'
or 'On'
. Default configuration
is disabled. When enabled, 'On'
, the carrier indication
field is present.
Data Types: char
| string
EnableSRSRequest
— Option to enable SRS request
'Off'
(default) | 'On'
| optional
Option to enable SRS request in the UE configuration, specified
as 'Off'
or 'On'
. By default, EnableSRSRequest
is
disabled. When EnableSRSRequest
is enabled ('On'
),
the SRS request field is present in UE-specific formats 0/1A for FDD
or TDD and formats 2B/2C/2D for TDD.
Data Types: char
| string
EnableMultipleCSIRequest
— Option to enable multiple CSI requests
'Off'
(default) | 'On'
| optional
Option to enable multiple CSI requests in the UE configuration,
specified as 'Off'
or 'On'
.
By default, EnableMultipleCSIRequest
is disabled.
When EnableMultipleCSIRequest
is enabled ('On'
),
the UE is configured to process multiple channel state information
(CSI) requests from cells. Enabling multiple CSI requests affects
the length of the CSI request field in UE-specific formats 0 and 4.
Data Types: char
| string
NTxAnts
— Number of UE transmission antennas
1 (default) | 2 | 4 | optional
Number of UE transmission antennas, specified as 1, 2, or 4. The number of UE transmission antennas affects the length of the precoding information field in DCI format 4.
Data Types: double
Data Types: struct
softbits
— Input vector of soft bits
numeric column vector
Input vector of soft bits, specified as a column vector.
Data Types: double
Output Arguments
dcistr
— Downlink control information (DCI) message structures
cell array of structures
Downlink control information (DCI) message structures, returned
as a cell array of structures. Each structure represents a successfully
decoded DCI whose fields match fields of the associated DCI format.
Each structure contains the fields associated with one or more decoded
DCI messages. Because multiple PDCCHs can be transmitted in a subframe,
the UE must monitor all possible PDCCHs directed at it. If more than
one PDCCH is directed to the UE or is successfully decoded, dcistr
contains
that number of decoded DCI messages.
Each cell contains a structure with the fields associated with the DCI format of the received PDCCHs.
DCIFormat
— DCI format type
'Format0'
| 'Format1'
| 'Format1A'
| 'Format1B'
| 'Format1C'
| 'Format1D'
| 'Format2'
| 'Format2A'
| 'Format2B'
| 'Format2C'
| 'Format3'
| 'Format3A'
| 'Format4'
| 'Format5'
DCI format type, specified as a character vector. This table presents the fields associated with each DCI format as defined in TS 36.212 [1], Section 5.3.3.
DCI Formats | dciout Fields | Size | Description |
---|---|---|---|
'Format0' | DCIFormat | - | 'Format0' |
CIF | 0 or 3 bits | Carrier indicator field | |
FreqHopping | 1 bit | PUSCH frequency hopping flag | |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation, coding scheme, and redundancy version | |
NewData | 1 bit | New data indicator | |
TPC | 2 bits | PUSCH TPC command | |
CShiftDMRS | 3 bits | Cyclic shift for DM RS | |
TDDIndex | 2 bits | For TDD config 0, this field is the Uplink Index. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
CSIRequest | 1, 2, or 3 bits | CSI request | |
SRSRequest | 0 or 1 bit | SRS request. This field can only be present in DCI formats scheduling PUSCH which are mapped onto the UE specific search space given by the C-RNTI | |
AllocationType | 1 bit | Resource allocation type, only present if ≤. | |
'Format1' | DCIFormat | - | 'Format1' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation and coding scheme | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
NewData | 1 bit | New data indicator | |
RV | 2 bits | Redundancy version | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format1A' | DCIFormat | - | 'Format1A' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | VRB assignment flag: 0 (localized), 1 (distributed) | |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation and coding scheme | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
NewData | 1 bit | New data indicator | |
RV | 2 bits | Redundancy version | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
SRSRequest | 0 or 1 bit | SRS request. This field can only be present in DCI formats scheduling PUSCH which are mapped onto the UE specific search space given by the C-RNTI | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format1B' | DCIFormat | - | 'Format1B' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | VRB assignment flag: 0 (localized), 1 (distributed) | |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation and coding scheme | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
NewData | 1 bit | New data indicator | |
RV | 2 bits | Redundancy version | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
TPMI | 2 bits for two antennas 4 bits for four antennas | PMI information | |
PMI | 1 bit | PMI confirmation | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format1C' | DCIFormat | - | 'Format1C' |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation and coding scheme | |
'Format1D' | DCIFormat | - | 'Format1D' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | VRB assignment flag: 0 (localized), 1 (distributed) | |
Allocation | Varies | Resource block assignment/allocation | |
ModCoding | 5 bits | Modulation and coding scheme | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
NewData | 1 bit | New data indicator | |
RV | 2 bits | Redundancy version | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
TPMI | 2 bits for two antennas 4 bits for four antennas | Precoding TPMI information | |
DlPowerOffset | 1 bit | Downlink power offset | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format2' | DCIFormat | - | 'Format2' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
SwapFlag | 1 bit | Transport block to codeword swap flag | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
RV1 | 2 bits | Redundancy version for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
RV2 | 2 bits | Redundancy version for transport block 2 | |
PrecodingInfo | 3 bits for two antennas 6 bits for four antennas | Precoding information | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format2A' | DCIFormat | - | 'Format2A' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
SwapFlag | 1 bit | Transport block to codeword swap flag | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
RV1 | 2 bits | Redundancy version for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
RV2 | 2 bits | Redundancy version for transport block 2 | |
PrecodingInfo | 0 bits for two antennas 2 bits for four antennas | Precoding information | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format2B' | DCIFormat | - | 'Format2B' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
ScramblingId | 1 bit | Scrambling identity | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
RV1 | 2 bits | Redundancy version for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
RV2 | 2 bits | Redundancy version for transport block 2 | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format2C' | DCIFormat | - | 'Format2C' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
TxIndication | 3 bits | Antenna ports, scrambling identity, and number of layers indicator | |
SRSRequest | Varies | SRS request. Only present for TDD. | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
RV1 | 2 bits | Redundancy version for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
RV2 | 2 bits | Redundancy version for transport block 2 | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format2D' | DCIFormat | - | 'Format2D' |
CIF | 0 or 3 bits | Carrier indicator field | |
AllocationType | 1 bit | Resource allocation header: type 0, type 1. If downlink bandwidth is ≤10 PRBs there is no resource allocation header and resource allocation type 0 is assumed. | |
Allocation | Varies | Resource block assignment/allocation | |
TPCPUCCH | 2 bits | PUCCH TPC command | |
TDDIndex | 2 bits | For TDD config 0, this field is not used. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
HARQNo | 3 bits (FDD) 4 bits (TDD) | HARQ process number | |
TxIndication | 3 bits | Antenna ports, scrambling identity, and number of layers indicator | |
SRSRequest | Varies | SRS request. Only present for TDD. | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
RV1 | 2 bits | Redundancy version for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
RV2 | 2 bits | Redundancy version for transport block 2 | |
REMappingAndQCL | 2 bits | PDSCH RE Mapping and Quasi-Co-Location Indicator | |
HARQACKResOffset | 2 bits | HARQ-ACK resource offset. Present when this format is carried by EPDCCH. Not present when this format is carried by PDCCH | |
'Format3' | DCIFormat | - | 'Format3' |
TPCCommands | Varies | TPC commands for PUCCH and PUSCH | |
'Format3A' | DCIFormat | - | 'Format3A' |
TPCCommands | Varies | TPC commands for PUCCH and PUSCH | |
'Format4' | DCIFormat | - | 'Format4' |
CIF | 0 or 3 bits | Carrier indicator field | |
Allocation | Varies | Resource block assignment/allocation | |
TPC | 2 bits | PUSCH TPC command | |
CShiftDMRS | 3 bits | Cyclic shift for DM-RS | |
TDDIndex | 2 bits | For TDD config 0, this field is Uplink Index. For TDD config 1–6, this field is the Downlink Assignment Index. Not present for FDD. | |
CSIReq | Varies | CSI request | |
SRSRequest | 2 bits | SRS request | |
AllocationType | 1 bit | Resource allocation header type 0 or type 1. | |
ModCoding | 5 bits | Modulation, coding scheme, and redundancy version | |
NewData | 1 bit | New data indicator | |
ModCoding1 | 5 bits | Modulation and coding scheme for transport block 1 | |
NewData1 | 1 bit | New data indicator for transport block 1 | |
ModCoding2 | 5 bits | Modulation and coding scheme for transport block 2 | |
NewData2 | 1 bit | New data indicator for transport block 2 | |
PrecodingInfo | 3 bits for two antennas 6 bits for four antennas | Precoding information | |
'Format5' | DCIFormat | - | 'Format5' |
PSCCHResource | 6 bits | Resource for PSCCH | |
TPC | 1 bit | TPC command for PSCCH and PSSCH | |
FreqHopping | 1 bit | Frequency hopping flag | |
Allocation | Varies | Resource block assignment and hopping resource allocation | |
TimeResourcePattern | 7 bits | Time resource pattern | |
'Format5A' | DCIFormat | - | 'Format5A' |
CIF | 3 bits | Carrier indicator | |
FirstSubchannelIdx | Lowest index of the subchannel allocation to the initial transmission | ||
RIV | from 0 to 13 bits, | Resource indication value | |
TimeGap | 4 bits |
Time gap between initial transmission and retransmission | |
SLIndex | 2 bits | SL SPS configuration index |
Data Types: char
Data Types: cell
dcibits
— DCI message bits
cell array of numeric vectors
DCI message bits, returned as a cell array of one or more numeric
vectors. Each vector contains the bit stream of a recovered DCI message,
including any zero-padding. Each vector of bit values corresponds
to successfully decoded DCI messages. For more information, see lteDCI
.
Data Types: cell
More About
PDCCH Search Processing
PDCCH search processing blindly decodes DCI
messages based on their lengths. The lengths and order in which DCI
messages are searched for is provided by lteDCIInfo
.
If one or more messages have the same length, the first message format
in the list is used to decode the message. The other potential message
formats are ignored. The ltePDCCHSearch
function
does not consider transmission mode (TM) during blind search, and
no DCI message format is filtered based on transmission mode. It also
does not search for format 3 and 3A (power adjustment commands for
PUSCH and PUCCH). For more information on the association between
transmission mode, transmission scheme, DCI format, and search space,
see TS 36.213 [2], Section
7.1 and Table 7.1-5.
The UE is required to monitor multiple PDCCHs within the control
region. The UE is informed only of the width, in OFDM symbols, of
the control region within a subframe, and is not aware of the exact
location of PDCCHs relevant to it. The UE finds the PDCCHs relevant
to it by monitoring a set of PDCCH candidates, that is, a set of consecutive
control candidate elements (CCEs) on which PDCCH can be mapped, in
every subframe. For details, see ltePDCCHSpace
.
This process is referred to as blind decoding.
To simplify the decoding task at the UE, the whole control region is subdivided into common and UE-specific search spaces which the UE monitors (monitor implies attempting to decode each PDCCH). Each search space comprises 2, 4, or 6 PDCCH candidates whose data length depends on its corresponding PDCCH format. Each PDCCH must be transmitted on 1, 2, 4, or 8 CCE (1 CCE = 72 bits). The common search space is limited to only two aggregation levels, 4 and 8, while the UE-specific search space can have an aggregation level of 1, 2, 4, or 8.
All UEs within a cell monitor the common search space that carries control information common to all UEs. The common control information carries initial important information including paging information, system information, and random access procedures. The UE monitors the common search space by demasking each PDCCH candidate with different RNTIs, for example, P-RNTI, SI-RNTI, RA-RNTI and so on.
In the UE-specific search space, the UE finds the PDCCH relevant to it by monitoring a set of PDCCH candidates in every subframe. If no CRC error is detected when the UE demasks a PDCCH candidate with its RNTI (16-bit C-RNTI value), the UE determines that the PDCCH candidate carries its own control information.
The number and location of candidates within a search space is different for each PDCCH format. There are four PDCCH formats (0, 1, 2, or 3). If the UE fails to decode any PDCCH candidates for a given PDCCH format, it tries to decode candidates for another PDCCH format.
Specifying Number of Resource Blocks
The number of resource blocks specifies the
uplink and downlink bandwidth. The LTE Toolbox™ implementation
assumes symmetric link bandwidth unless you specifically assign different
values to NULRB
and NDLRB
. If
the number of resource blocks is initialized in only one link direction,
then the initialized number of resource blocks (NULRB
or NDLRB
)
is used for both uplink and downlink. When this mapping is used, no
warning is displayed. An error occurs if NULRB
and NDLRB
are
both undefined.
References
[1] 3GPP TS 36.212. “Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
[2] 3GPP TS 36.213. “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures.” 3rd Generation Partnership Project; Technical Specification Group Radio Access Network. URL: https://www.3gpp.org.
Version History
Introduced in R2014a
See Also
ltePDCCH
| ltePDCCHDecode
| ltePDCCHIndices
| ltePDCCHInterleave
| ltePDCCHDeinterleave
| ltePDCCHInfo
| ltePDCCHSpace
| ltePDCCHPRBS
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