- The document discusses LTE physical channels, transport channels, and logical channels. It provides details on the different channels used in the downlink and uplink. - The main physical channels described include the PBCH, PCFICH, PDCCH, PHICH, PUCCH, PUSCH, and PRACH. The transport channels include the BCH, DL-SCH, PCH, MCH, UL-SCH, and RACH. The logical channels include the BCCH, PCCH, CCCH, MCCH, DCCH, DTCH, and MTCH. - Link adaptation procedures for the downlink and uplink are also summarized, including how CQI is used to determine the

1. General:
1 RB = 6 Sub-Carriers

2. Channels:
There are three categories into which the various data channels may be grouped.
 Physical channels: These are transmission channels that carry user data and control
messages.
 Transport channels: The physical layer transport channels offer information transfer to
Medium Access Control (MAC) and higher layers.
 Logical channels: Provide services for the Medium Access Control (MAC) layer within the
LTE protocol structure.
3G LTE physical channels
The LTE physical channels vary between the uplink and the downlink as each has different
requirements and operates in a different manner.
 Downlink:
o Physical Broadcast Channel (PBCH): This physical channel carries system
information for UEs requiring to access the network. It only carries what is termed
Master Information Block, MIB, messages. The modulation scheme is always QPSK and
the information bits are coded and rate matched - the bits are then scrambled using a
scrambling sequence specific to the cell to prevent confusion with data from other
cells.
The MIB message on the PBCH is mapped onto the central 72 subcarriers or six central
resource blocks regardless of the overall system bandwidth. A PBCH message is
repeated every 40 ms, i.e. one TTI of PBCH includes four radio frames. The PBCH is
designed to be detectable without prior knowledge of system bandwidth and to be
accessible at the cell edge. The MIB is coded at a very low coding rate and mapped to
the 72 center sub-carriers (6 RBs) of the OFDM structure. PBCH transmission is spread
over four 10 ms frames (over subframe #0) to span a 40 ms period as shown in Error!
Reference source not found.. Each subframe is self-decodable which reduces latency
and UE battery drain in case of good signal quality, otherwise, the UE would 'soft-
combine' multiple transmissions until the PBCH is decoded. The PBCH is transmitted
using Space Frequency Block Code (SFBC), a form of transmit diversity, in case of
multiple antennas thereby allowing for greater coverage.
The PBCH transmissions have 14 information bits, 10 spare bits, and 16 CRC bits.

3. o Physical Control Format Indicator Channel (PCFICH): As the name implies the
PCFICH informs the UE about the format of the signal being received. It indicates the
number of OFDM symbols used for the PDCCHs, whether 1, 2, or 3. The information
within the PCFICH is essential because the UE does not have prior information about
the size of the control region.
A PCFICH is transmitted on the first symbol of every sub-frame and carries a Control
Format Indicator, CFI, field. The CFI contains a 32 bit code word that represents 1, 2,
or 3. CFI 4 is reserved for possible future use.
The PCFICH uses 32,2 block coding which results in a 1/16 coding rate, and it always
uses QPSK modulation to ensure robust reception.
o Physical Downlink Control Channel (PDCCH) : The main purpose of this physical
channel is to carry mainly scheduling information of different types:
 Downlink resource scheduling
 Uplink power control instructions
 Uplink resource grant
 Indication for paging or system information
The PDCCH contains a message known as the Downlink Control Information, DCI
which carries the control information for a particular UE or group of UEs. The DCI
format has several different types which are defined with different sizes. The different
format types include: Type 0, 1, 1A, 1B, 1C, 1D, 2, 2A, 2B, 2C, 3, 3A, and 4.
o Physical Hybrid ARQ Indicator Channel (PHICH) : As the name implies, this
channel is used to report the Hybrid ARQ status. It carries the HARQ ACK/NACK signal
indicating whether a transport block has been correctly received. The HARQ indicator
is 1 bit long - "0" indicates ACK, and "1" indicates NACK.
The PHICH is transmitted within the control region of the subframe and is typically
only transmitted within the first symbol. If the radio link is poor, then the PHICH is
extended to a number symbols for robustness.
 Uplink:
o Physical Uplink Control Channel (PUCCH) : The Physical Uplink Control Channel,
PUCCH provides the various control signaling requirements. There are a number of

4. different PUCCH formats defined to enable the channel to carry the required
information in the most efficient format for the particular scenario encountered. It
includes the ability to carry SRs, Scheduling Requests.
The basic formats are summarized below:
PUCCH
FORMAT
UPLINK CONTROL INFORMATION MODULATION
SCHEME
BITS PER SUB-
FRAME
NOTES
Format 1 SR N/A N/A
Format 1a 1 bit HARQ ACK/NACK with or
without SR
BPSK 1
Format 1b 2 bit HARQ ACK/NACK with or
without SR
QPSK 2
Format 2 CQI/PMI or RI QPSK 20
Format 2a CQI/PMI or RI and 1 bit HARQ
ACK/NACK
QPSK + BPSK 21
Format 2b CQI/PMI or RI and 2 bit HARQ
ACK/NACK
QPSK + BPSK 22
Format 3 Provides support for carrier
aggregation.
o Physical Uplink Shared Channel (PUSCH) : This physical channel found on the
LTE uplink is the Uplink counterpart of PDSCH
o Physical Random Access Channel (PRACH) : This uplink physical channel is used
for random access functions. This is the only non-synchronised transmission that the
UE can make within LTE. The downlink and uplink propagation delays are unknown
when PRACH is used and therefore it cannot be synchronised.
The PRACH instance is made up from two sequences: a cyclic prefix and a guard
period. The preamble sequence may be repeated to enable the eNodeB to decode the
preamble when link conditions are poor.
LTE transport channels
The LTE transport channels vary between the uplink and the downlink as each has different
requirements and operates in a different manner. Physical layer transport channels offer information
transfer to medium access control (MAC) and higher layers.
 Downlink:

5. o Broadcast Channel (BCH) : The LTE transport channel maps to Broadcast Control
Channel (BCCH)
o Downlink Shared Channel (DL-SCH) : This transport channel is the main channel
for downlink data transfer. It is used by many logical channels.
o Paging Channel (PCH) : To convey the PCCH
o Multicast Channel (MCH) : This transport channel is used to transmit MCCH
information to set up multicast transmissions.
 Uplink:
o Uplink Shared Channel (UL-SCH) : This transport channel is the main channel for
uplink data transfer. It is used by many logical channels.
o Random Access Channel (RACH) : This is used for random access requirements.
LTE logical channels
The logical channels cover the data carried over the radio interface. The Service Access Point, SAP
between MAC sublayer and the RLC sublayer provides the logical channel.
 Control channels: these LTE control channels carry the control plane information:
o Broadcast Control Channel (BCCH) : This control channel provides system
information to all mobile terminals connected to the eNodeB.
o Paging Control Channel (PCCH) : This control channel is used for paging
information when searching a unit on a network.
o Common Control Channel (CCCH) : This channel is used for random access
information, e.g. for actions including setting up a connection.
o Multicast Control Channel (MCCH) : This control channel is used for Information
needed for multicast reception.
o Dedicated Control Channel (DCCH) : This control channel is used for carrying
user-specific control information, e.g. for controlling actions including power control,
handover, etc..
 Traffic channels:These LTE traffic channels carry the user-plane data:
o Dedicated Traffic Channel (DTCH) : This traffic channel is used for the
transmission of user data.
o Multicast Traffic Channel (MTCH) : This channel is used for the transmission of
multicast data.

6. PDCCH:
CCE - Control Channel Element
RE – Resource Element
1CCE = 9 RE group = 72 PDCCHbits
Relationwith AggressionLevel:
1) The numberof consecutive CCEsrequiredtocarry one PDCCHis called"AggregationLevel'.TS
36.211 Table 6.8.1.1 showsthese relations.
2) One PDCCH iscarriedby multiple numbersof consecutive CCEs.
 PDCCH Format0 : Requires1 CCE = AggregationLevel 1
 PDCCH Format1 : Requires2 CCE = AggregationLevel 2
 PDCCH Format2 : Requires4 CCE = AggregationLevel 4
 PDCCH Format3 : Requires8 CCE = AggregationLevel 8
PDCCH Candidate and SearchSpace:
1) All the possible locationforPDCCHiscalled'SearchSpace'and each of the possible locationis
called'PDCCHCandidates'.
2) The search space indicatesthe setof CCE locationswhere the UE mayfind itsPDCCHs.
3) There are twotypesof search space:
 Common– Aggressionlevel 4and 8
 UE Specific–Aggressionlevel 1,2, 4, 8
4) The UE specificandCommonsearchspace may overlapfora UE.
5) Belowtable showsthe relationbetweenAggressionLevel andSearchSpace i.e. how manyCCEs
a search space witha particularAggressionLevel willhave.

8. Physical uplink control channel
procedures
UCI (UplinkControl Information)
UCI standsfor UplinkControl Information.ItiscarriedbyPUCCH or PUSCH. It mayremind youof
DCI whichiscarriedby PDCCH.Yes, UCI isthe counterpart of DCI, butthe information/role of
UCI is verysmall comparingtoDCI ( I think).
The informationcarriedbyUCI ismainlyfollowingthree
 SR (SchedulingRequest)
 HARQ ACK/NACK
 CQI
UE transmita certaincombinationof these three informationdependingonsituation.
SometimesitcarriesonlySR,sometimesSRandHARQ ACK/NACKtogetheretc.
There are twochannelsthatcan carry the UCI. SometimesPDCCHcarriesUCIand sometimes
PUSCH carriesit.
Then when PUSCH carries UCIand when PDCCHcarries it ?
36.213 section10.1 UE procedure fordeterminingphysical uplinkcontrol channelassignment
describe itasfollows:
Uplinkcontrol information(UCI) insubframe nshall be transmitted
 on PUCCH usingformat1/1a/1b or 2/2a/2b if the UE isnot transmittingonPUSCHin
subframe n
 on PUSCH if the UE is transmittingonPUSCHinsubframe n unlessthe PUSCH
transmissioncorrespondstoa RandomAccessResponse Grantor a retransmissionof
the same transport blockas part of the contentionbasedrandomaccessprocedure,in
whichcase UCI isnot transmitted
Simplyput,whenUE transmitthe userdata and ithas to use PUSCH. In thiscase PUCCH is not
allowedtobe transmitted,inthiscase PUSCHcarriesUCI. Whenthere isno userdata to be
transmitted,PDCCHistransmittedcarryingUCIinit.

9. Link Adaptation in DL and UL:
1) Efficiency=numberof bits/Resource Element
2) No.of REs perRB is“Numberof PDSCH Resource ElementsinaPhysical Resource Block (PRB)”.
No.of REs perRB = ((No.of OFDMSymbols – No.of PDCCHSymbols) *Num of Subcarriersper
RB) – No of SymbolsforReference signals
No.of OFDMSymbols – 6 for extendedCPand7 for normal CP.
No.of PDCCHSymbols – 0, 1, 2, 3, 4 dependingonCell Configuration.
Numof SubcarriersperRB - 12
No of SymbolsforReference signals –Dependsonnumof Tx AntennaPorts.
3) There will be differentCQIreportedforULand DL. For DL the CQI will be receivedfromUEwhile
for UL eNBPHY will reportitbased onthe signal to noise ratio.
4) Basedon the CQI value,the efficiencyisfoundoutbasedonthe table 7.2.3-1 in36.213
Table 7.2.3-1: 4-bit CQI Table
CQI index modulation code rate x 1024 efficiency
0 out of range
1 QPSK 78 0.1523
2 QPSK 120 0.2344
3 QPSK 193 0.3770
4 QPSK 308 0.6016
5 QPSK 449 0.8770
6 QPSK 602 1.1758
7 16QAM 378 1.4766
8 16QAM 490 1.9141
9 16QAM 616 2.4063
10 64QAM 466 2.7305
11 64QAM 567 3.3223
12 64QAM 666 3.9023
13 64QAM 772 4.5234
14 64QAM 873 5.1152
15 64QAM 948 5.5547
Note:Since the efficiencyisintermsof floatingvalue,itismultipliedwith1024 sothat
calculationsare done inintegers.
Example:
CQI received=12
Efficiency (ECQI) = 3.9023 * 1024 = 3995 bits/RE
5) From the table 7.1.7.2.1-1 in36.213, find outthe average efficiencyforeachof the ITBS values
overthe PRBs. Belowisjusta portionof table.
Table 7.1.7.2.1-1: Transport block size table (dimension 27×110)
TBSI PRBN

10. 1 2 3 4 5 6 7 8 9 10
0 16 32 56 88 120 152 176 208 224 256
1 24 56 88 144 176 208 224 256 328 344
2 32 72 144 176 208 256 296 328 376 424
3 40 104 176 208 256 328 392 440 504 568
4 56 120 208 256 328 408 488 552 632 696
5 72 144 224 328 424 504 600 680 776 872
6 328 176 256 392 504 600 712 808 936 1032
7 104 224 328 472 584 712 840 968 1096 1224
8 120 256 392 536 680 808 968 1096 1256 1384
9 136 296 456 616 776 936 1096 1256 1416 1544
10 144 328 504 680 872 1032 1224 1384 1544 1736
11 176 376 584 776 1000 1192 1384 1608 1800 2024
12 208 440 680 904 1128 1352 1608 1800 2024 2280
13 224 488 744 1000 1256 1544 1800 2024 2280 2536
…
TBSI PRBN
101 102 103 104 105 106 107 108 109 110
13 26416 26416 26416 26416 27376 27376 27376 27376 28336 28336
14 29296 29296 29296 29296 30576 30576 30576 30576 31704 31704
15 30576 31704 31704 31704 31704 32856 32856 32856 34008 34008
16 32856 32856 34008 34008 34008 34008 35160 35160 35160 35160
17 36696 36696 36696 37888 37888 37888 39232 39232 39232 39232
18 40576 40576 40576 40576 42368 42368 42368 42368 43816 43816
19 43816 43816 43816 45352 45352 45352 46888 46888 46888 46888
20 46888 46888 48936 48936 48936 48936 48936 51024 51024 51024
21 51024 51024 51024 52752 52752 52752 52752 55056 55056 55056
22 55056 55056 55056 57336 57336 57336 57336 59256 59256 59256
23 57336 59256 59256 59256 59256 61664 61664 61664 61664 63776
24 61664 61664 63776 63776 63776 63776 66592 66592 66592 66592
25 63776 63776 66592 66592 66592 66592 68808 68808 68808 71112
So,a table iscreatedfromthistable whichwill have the average efficiencycorrespondingtoall
the ITBS value.
N = Numberof RE perPRB (forData)
n = numberof PRBs
Efficiencyof nPRBsfor ITBS j = (TBSNUM PRB n / (n* N)) * 1024
Example:Efficiency of 3 PRBsfor ITBS 13 = (744 / (3 * N)) * 1024
Average Efficiency forjth
ITBS = (Efficiencyof 1PRB for ITBS j + Efficiencyof 2 PRB forITBS j + … +
Efficiencyof 110 PRB for ITBS j) / 110
Example:(Average Efficiency)
For ITBS value 13.
N = 6 (say)
Efficiencyof 1 PRBfor ITBS 13 = (224 / (1 * 6)) * 1024 = 38229
Efficiencyof 2 PRBfor ITBS 13 = (448 / (2 * 6)) * 1024 = 38229
…

11. Efficiencyof 110 PRB for ITBS 13 = (28336 / (110 * 6)) * 1024 = 43963
Average Efficiency for13th
ITBS = (38229 + 38229 + … + 43963) / 110 ~= 40000 (say)
6) Compare the Efficiencyfoundinstep4withAverage value of ITBS Efficiency foundinstep5
startingfromITBS 0 until,the a greaterAverage Efficiencyforajth
ITBS isfound.
Loop until Average Efficiencyforjth
ITBS < ECQI
Example:So in ourExample,the ITBSvalue 13 will be the result.
7) Selectthe j-1ITBS value
Example:Thus the ITBS value one lesserthanthiswill be selectedi.e.12.
8) ThisITBS value will be mappedtothe table 7.7.7.1-1 (For DL) and table 8.6.1-1 (ForUL) forfinding
the ModulationOrder.
Table 7.1.7.1-1: Modulation and TBS index table for PDSCH
MCS Index
MCSI
Modulation Order
mQ
TBS Index
TBSI
0 2 0
1 2 1
2 2 2
3 2 3
4 2 4
5 2 5
6 2 6
7 2 7
8 2 8
9 2 9
10 4 9
11 4 10
12 4 11
13 4 12
14 4 13
15 4 14
16 4 15
17 6 15
18 6 16
19 6 17
20 6 18
21 6 19
22 6 20
23 6 21
24 6 22
25 6 23
26 6 24
27 6 25
28 6 26
29 2
reserved30 4
31 6

12. Table 8.6.1-1: Modulation, TBS index and redundancy version table for PUSCH
MCS Index
MCSI
Modulation
Order
'
mQ
TBS
Index
TBSI
Redundancy
Version
rvidx
0 2 0 0
1 2 1 0
2 2 2 0
3 2 3 0
4 2 4 0
5 2 5 0
6 2 6 0
7 2 7 0
8 2 8 0
9 2 9 0
10 2 10 0
11 4 10 0
12 4 11 0
13 4 12 0
14 4 13 0
15 4 14 0
16 4 15 0
17 4 16 0
18 4 17 0
19 4 18 0
20 4 19 0
21 6 19 0
22 6 20 0
23 6 21 0
24 6 22 0
25 6 23 0
26 6 24 0
27 6 25 0
28 6 26 0
29
reserved
1
30 2
31 3
Example:
For DL (From table 7.1.7.1-1),ModulationOrderforITBS = 4
For DL (From table 8.6.1-1),ModulationOrderforITBS = 4
Now,if BO is500 bitsthenTBS shouldbe at least= 500 * 3.9023 (fromECQI) = 1951
So,selectthe TBs justabove the 1951 from the table 7.1.7.2.1-1 againstthe ITBS 12. It is2024.
Thus,numberof PRBs will be 9.

13. 1 REG (Resource ElementGroup) =4 consecutive REs
1 CCE (Control Channel Element)=9 REGs
1 PDCCHis transmittedinone ormore CCE.

14. The numberof CCEsaggregated for transmissionof aparticularPDCCHis knownasthe ‘aggregation
level’andisdeterminedbythe eNodeBaccordingtothe channel conditions.
The set of CCE locationsinwhichthe UE may finditsPDCCHscan be consideredasa
‘searchspace’.
Antenna Ports:
Transmit Diversity:
Use transmit diversity (tx diversity) to diminish the effects of fading by transmitting the same information
from two different antennas. The data from the second antenna (Open Loop Antenna 2) is encoded
differently to distinguish it from the primary antenna (Open Loop Antenna 1). The user equipment (UE)
must be able to recognize that the information is coming from two different locations and properly decode
the data.
The transmit diversity feature uses STTD encoding to differentiate the signals between Open Loop
Antenna 1 (Antenna 1) and Open Loop Antenna 2 (Antenna 2) on the following channels:
 P-CCPCH
 PICH
 DPCH
 HS-PDSCH
 HS-SCCH
 OCNS
The CPICH is not STTD encoded, but it is affected by transmit diversity. Even though it is transmitted
from both antennas, its predefined bit sequence differs between antenna one and antenna two per the
3GPP specifications. The SCH uses TSTD encoding and is phase inverted.
Using both antenna setups at the same time, requires the use of two ESGs and two Signal Studio for
3GPP W-CDMA HSPA software sessions. When using the two antenna setup, you must synchronize the
signals between the two ESGs.

15. Physical Control Format Indicator Channel (PCFICH):
 As the name suggests, this channel communicates the number of OFDMA symbols that the
PDCCH will be transmitted on, to the UE.
 The PDCCH can take either {1,2,3} OFDMA symbols for BW > 1.4 MHz and values {2,3,4} for
BW 1.4 Mhz.
 The two bits required to carry one of the 4 values is encoded into 32 bits. QPSK modulation is
used which yields 16 bits to be transmitted.
 The 16 bits for the PCFICH are spread over 16 REs in 4 groups of 4 REs each. This provides
added protection from frequency selective fading.
 The PCFICH shall be transmitted on the same set of antenna ports as the PBCH.
 The PCFICH is spread over the whole range of sub-carriers which provides it with some immunity
to the frequency selective fading
 PCFICH signaled value depends on channel bandwidth. For channel bandwidth of 3MHz up to 20
Mhz it can carry value of 1, 2 or 3. But for 1.4 Mhz channel bandwidth it can carry value of 2, 3 or
4. Because in case of 1.4 Mhz bandwidth, there are few subcarriers in frequency domain.
Therefore, more space is required in time domain to carry PDCCH symbols
PCFICH and PDCCH Channel

16. Physical downlink control channel(PDCCH):
 The PDCCH is the control channel which is specified by the PCFICH, as shown in the figure
above.
 The channel carries downlink assignments for data on the Physical Downlink Shared Channel
(PDSCH)
 The modulation used in QPSK
 The number of OFDMA symbols occupied by PDCCH in the first slot of each sub frame is given
by PCFICH (in absence of PCFICH, the PDCCH is also absent).