PDCCH carries DCI (DOWNLINK Control), which contains resource allocation and other control information on one or more UE. The resource scheduling information (MCS, Resource, etc.) in the LTE is all carried by PDCCH. Generally speaking, there are multiple PDCCHs in one subframe. The UE needs to discrete the DCI in the PDCCH before being able to decompose the UE's own PDSCH (including broadcast messages, paging, UE's data, etc.) Over the time, the number of symbols occupied by PDCCH in a subframe (note that it is not the time) is determined by the CFI defined in the PCFICH. Through the master and auxiliary synchronization channels, the UE determines the physical ID PCI of the community. By reading PBCH, the resource distribution of Phich occupied by the read, the system antenna port of the system. UE can further read PCFICH to understand the number of symbols occupied by control channels such as PDCCH. In the symbol occupied by PDCCH, in addition to PDCCH, it also contains PCFICH, Phich, RS and other content. Among them, the content of PCFICH has been demodulated, and the distribution of Phich is determined by PBCH. The distribution of RS depends on the number of antenna ports in PBCH. At this point, (all) pdcch can be determined in a subframe.
It because the transmission bandwidth of the PDCCH can also include multiple PDCCH at the same time. In order to more effectively configure the time -frequency resources of PDCCH and other downlink control channels, LTE defines two dedicated control channel resource units: RE Group (RE Group, REG) and Control Channel Element (CCE). 1 R consists of 4 or 6 adjacent RE on the same OFDM symbol, but there are only 4 REGs available in them. The occupied REG cannot be used by control channels. In the agreement (36.211), it also specifically stipulates that for the situation where there is only a special reference signal of only one community, from the perspective of REG in the REG, it is necessary to assume that there are two antenna ports, so there are 4 or 6 REs in one REG. Essence A CCE consists of 9 REG. Defining resource units such as REG are mainly to effectively support the resource allocation of control channels with small data rates such as PCFICH and Phich. CCE is allocated to allocate the resource allocation of PDCCH with a relatively large amount of data.
pdcch is transmitted on one or more continuous CCE. LTE supports different types of PDCCH in 4, as shown in the figure below:
pdcch format number of ccess number of resource-element group number of pdcch bits n0 n 1 9 n1 n1 n1 n1 n1 n1 n1 n1 2 18 144
2 36 288 n3 8 72 576
LTE, the number and allocation of CCE are continuous. If the number of REGs after the system assigns PCFICH and Phich is NREG, the number of CCE available for PDCCH is ncce = nreg/9. The number of CCE is from 0 to NCCE -1.
PDCCH occupied by CCE depends on the downward channel environment where the UE is located. For the UE with a good downward channel environment, ENODEB may only allocate one CCE. For UE with poor downward channel environment, ENODEB may be possible. Need to allocate up to 8 CCEs. In order to simplify the complexity of the UE when decoding PDCCH, the LTE also stipulates that the number of CCEs is N PDCCH. The CCE number of its starting position must be an integer multiple of N.
It each PDCCH, contains a 16bit CRC verification, UE is used to verify whether the receiving PDCCH is correct, and the CRC uses Identity related to UE to make the disturbance code, so that the UE can determine which PDCCH is the What you need to receive is sent to other UEs. UE Identity that can be used to make disturbances includes: C -RNTI, SPS -RNTI, and public Si -RNTI, P -RNTI, and RA -RANTI.
each PDCCH, after CRC check, perform TBCC channel coding and rate matching. ENODEB can be matched according to the CQI (Channel Quality Indicator) reported on the UE. At this time, for each PDCCH, the size of the CCE it occupies can be determined.
This has been mentioned earlier, the number of cce available CCE is from 0 to NCCE -1. CCE can be regarded as logical resources, arranged in order, and shared all PDCCH. ENODEB places each PDCCH in a suitable position based on the restrictions on the starting position on each PDCCH. At this time, some CCEs may not be occupied. The standards need to be inserted in the standard. The sending power on the RE corresponding to NIL is -INF, which is 0.
M n Since then, the data on the CCE via the community physical ID -related disturbance code, QPSK modulation, layer mapping and pre -coding. The meta -group was mapped to a REG) to interweave and circulate the displacement, and finally mapped it to the corresponding physical resource REG.
The physical resource REG is first allocated to PCFICH and Phich, and the remaining is allocated to PDCCH, and the REG mapping is performed in accordance with the principle of the frequency domain of the time domain. The purpose of this is to avoid unevenness between the PDCCH symbols.
1, several PDCCH can be passed in a subframe. The so-called PDCCH here refers to a DCI, which has the corresponding format, adds 16bit CRC, and then adds to the X-RNTI, and then tail biting, rate match a better sequence.
The PDCCH is divided into 4 of 4, which corresponds to 1, 2, 4, and 8 CCEs, respectively. How many CCEs do a DCI information occupy is determined by the ENB side based on the quality of the UE's downward channel. The channel conditions are good, which is shorter, and the difference is long.
2, several pdcch reuse is to connect the above bit. b1 (0), B1 (1), ..., B1 (M1), B2 (0), B2 (1) ..... This way
.jpg (32.02 kb) 2011-12-27 13: 15
The reuse above is actually the mapping of the virtual resource from each PDCCH to the virtual resource of reg Number. There may be INF (zero) in the middle. 1. Brief description of the entire process of PDCCH, in fact, I have already written it before, but now I feel that it is not thorough. The CRC of various DCI (usually some people call a DCI called a PDCCH) ---- "RNTI addition (the RNTI type of the god horse type depends on what the UE wants to do now, what is needed, or what the DCI passes) ----》 ENCODER ---》 Ratemach ----》 PDCCH reuse (after NIL) ----》 Bit bias --- "qpsk modulation ---"
PDCCH carries DCI (DOWNLINK Control), which contains resource allocation and other control information on one or more UE. The resource scheduling information (MCS, Resource, etc.) in the LTE is all carried by PDCCH. Generally speaking, there are multiple PDCCHs in one subframe. The UE needs to discrete the DCI in the PDCCH before being able to decompose the UE's own PDSCH (including broadcast messages, paging, UE's data, etc.)
Over the time, the number of symbols occupied by PDCCH in a subframe (note that it is not the time) is determined by the CFI defined in the PCFICH. Through the master and auxiliary synchronization channels, the UE determines the physical ID PCI of the community. By reading PBCH, the resource distribution of Phich occupied by the read, the system antenna port of the system. UE can further read PCFICH to understand the number of symbols occupied by control channels such as PDCCH. In the symbol occupied by PDCCH, in addition to PDCCH, it also contains PCFICH, Phich, RS and other content. Among them, the content of PCFICH has been demodulated, and the distribution of Phich is determined by PBCH. The distribution of RS depends on the number of antenna ports in PBCH. At this point, (all) pdcch can be determined in a subframe.
It because the transmission bandwidth of the PDCCH can also include multiple PDCCH at the same time. In order to more effectively configure the time -frequency resources of PDCCH and other downlink control channels, LTE defines two dedicated control channel resource units: RE Group (RE Group, REG) and Control Channel Element (CCE). 1 R consists of 4 or 6 adjacent RE on the same OFDM symbol, but there are only 4 REGs available in them. The occupied REG cannot be used by control channels. In the agreement (36.211), it also specifically stipulates that for the situation where there is only a special reference signal of only one community, from the perspective of REG in the REG, it is necessary to assume that there are two antenna ports, so there are 4 or 6 REs in one REG. Essence A CCE consists of 9 REG. Defining resource units such as REG are mainly to effectively support the resource allocation of control channels with small data rates such as PCFICH and Phich. CCE is allocated to allocate the resource allocation of PDCCH with a relatively large amount of data.
pdcch is transmitted on one or more continuous CCE. LTE supports different types of PDCCH in 4, as shown in the figure below:
pdcch format
number of ccess
number of resource-element group
number of pdcch bits
n0 n 1
9
n1 n1 n1 n1 n1 n1 n1 n1
2
18
144
2
36
288
n3
8
72
576
LTE, the number and allocation of CCE are continuous. If the number of REGs after the system assigns PCFICH and Phich is NREG, the number of CCE available for PDCCH is ncce = nreg/9. The number of CCE is from 0 to NCCE -1.
PDCCH occupied by CCE depends on the downward channel environment where the UE is located. For the UE with a good downward channel environment, ENODEB may only allocate one CCE. For UE with poor downward channel environment, ENODEB may be possible. Need to allocate up to 8 CCEs. In order to simplify the complexity of the UE when decoding PDCCH, the LTE also stipulates that the number of CCEs is N PDCCH. The CCE number of its starting position must be an integer multiple of N.
It each PDCCH, contains a 16bit CRC verification, UE is used to verify whether the receiving PDCCH is correct, and the CRC uses Identity related to UE to make the disturbance code, so that the UE can determine which PDCCH is the What you need to receive is sent to other UEs. UE Identity that can be used to make disturbances includes: C -RNTI, SPS -RNTI, and public Si -RNTI, P -RNTI, and RA -RANTI.
each PDCCH, after CRC check, perform TBCC channel coding and rate matching. ENODEB can be matched according to the CQI (Channel Quality Indicator) reported on the UE. At this time, for each PDCCH, the size of the CCE it occupies can be determined.
This has been mentioned earlier, the number of cce available CCE is from 0 to NCCE -1. CCE can be regarded as logical resources, arranged in order, and shared all PDCCH. ENODEB places each PDCCH in a suitable position based on the restrictions on the starting position on each PDCCH. At this time, some CCEs may not be occupied. The standards need to be inserted in the standard. The sending power on the RE corresponding to NIL is -INF, which is 0.
M n Since then, the data on the CCE via the community physical ID -related disturbance code, QPSK modulation, layer mapping and pre -coding. The meta -group was mapped to a REG) to interweave and circulate the displacement, and finally mapped it to the corresponding physical resource REG.
The physical resource REG is first allocated to PCFICH and Phich, and the remaining is allocated to PDCCH, and the REG mapping is performed in accordance with the principle of the frequency domain of the time domain. The purpose of this is to avoid unevenness between the PDCCH symbols.
1, several PDCCH can be passed in a subframe. The so-called PDCCH here refers to a DCI, which has the corresponding format, adds 16bit CRC, and then adds to the X-RNTI, and then tail biting, rate match a better sequence.
The PDCCH is divided into 4 of 4, which corresponds to 1, 2, 4, and 8 CCEs, respectively. How many CCEs do a DCI information occupy is determined by the ENB side based on the quality of the UE's downward channel. The channel conditions are good, which is shorter, and the difference is long.
2, several pdcch reuse is to connect the above bit.
b1 (0), B1 (1), ..., B1 (M1), B2 (0), B2 (1) ..... This way
.jpg (32.02 kb)
2011-12-27 13: 15
The reuse above is actually the mapping of the virtual resource from each PDCCH to the virtual resource of reg Number. There may be INF (zero) in the middle. 1. Brief description of the entire process of PDCCH, in fact, I have already written it before, but now I feel that it is not thorough. The CRC of various DCI (usually some people call a DCI called a PDCCH) ---- "RNTI addition (the RNTI type of the god horse type depends on what the UE wants to do now, what is needed, or what the DCI passes) ----》 ENCODER ---》 Ratemach ----》 PDCCH reuse (after NIL) ----》 Bit bias --- "qpsk modulation ---"