This document discusses the overall EPS architecture and air interface capabilities in LTE such as OFDMA and SC-FDMA based radio access. It describes aspects of the downlink physical resource such as synchronization signals, reference signals, control channels, and shared data channels. Additionally, it provides examples of downlink transmissions and scheduling principles as well as HARQ operations in the channel access design of LTE.

2. Overall EPSArchitecture

3. E-UTRAAir Interface Capabilities

4. OFDMAand SC-FDMABased RadioAccess

7. Multi-carrier principle

9. Multi-path Fading

10. OFDMAresource allocation in LTE

11. Resource mapping in SC-FDMA

12. Channel mapping

13. Channel mapping

15. Time-domain structure FDD

16. Time-domain structure TDD.

17. The LTE downlink physical resource

18. Frequency Domain Configurations

19. TDD Uplink Downlink Configurations

20. Synchronization Signals (PSS & SSS)

21. P-SS(Primary Synchronization Signal)
• Mapped to 72 active sub carriers(6 resource blocks),
centered around the DC subcarrier in slot 0 (Sub frame 0)
and slot 10 (Sub frame 5). Made up of 62 Zadoff Chu
Sequence Values Used for Downlink Frame
Synchronization One of the critical factors determining
Physical Cell ID

22. S-SS(Secondary Synchronization Signal)
• Mapped to 72 active sub carriers(6 resource blocks),
centered around the DC subcarrier in slot 0 (Sub frame 0)
and slot 10 (Sub frame 5) in FDD. The sequence of SSS
in sub frame 0 and the one in sub frame 5 are different
from each other Made up of 62 Scrambling Sequence
(based on m-sequence) The value in odd indexed
resource element and the one in even indexed resource
elements is generated by different equation Used for
Downlink Frame Synchronization

23. Physical Cell ID
• Physical Cell ID is an identification of a cell at physical
layer. It has similar role as Primary Scrambling Code of
UMTS
• cell.

24. Physical Broadcast Channel (PBCH)

25. PBCH(Physical Broadcast Channel)
• It carries only the MIB.
• It is using QPSK.
• Mapped to 6 Resource Blocks (72 subcarriers), centered around
DC subcarrier in sub frame 0.
• Mapped to Resource Elements which is not reserved for
transmission of reference signals, PDCCH or PHICH

26. Physical Control Format Indicator
Channel (PCFICH)
•It carries the number of symbols that can be used
for control channels (PDCCH and PHICH).
•Mapped to the first OFDM symbol in each of the
downlink sub-frame. This contains the information on
number of OFDM symbols carrying the control
channels (PDCCH and PHICH). UE decode this
channel to figure out how many OFDM symbols are
assigned for the control channels(PDCCH and PHICH)
•It is 16 data subcarriers of the first OFDM symbol of
the sub frame.
•PCFICH data is carried by 4 REGs and these four
REGs are evenly distributed across the whole band
regardless of the bandwidth.
•The exact position of PCFICH is determined by cell
ID and bandwidth.

27. Physical Downlink Control Channel
(PDCCH)
Mapped to the first L OFDM symbols in each of the
downlink sub-frame.
Number of the symbols (L) for PDCCH can be 1,2, or 3.
Number of the symbols for PDCCH is specified by
PCFICH PDCCH carries DCIs and the DCI
carries Transport format, resource allocation, H-ARQ
information related to DL-SCH, UL-SCH and PCH and
other additional information depending on DCI format.
PDCCH also carries DCI 0 which is for UL Scheduling
assignment (e.g, UL Grants). Multiple PDCCH can be
assigned in single sub frame and a UE do blind decoding
of all the PDCCHs. Modulation Scheme is QPSK

28. Physical HARQ Indicator Channel
(PHICH)
PHICH stands for Physical channel Hybrid ARQ
Indicator Channel. Simply put, it is a specially
designed downlink only channel which carries
ACK or NACK for the PUSCH received by the
network.
Uplink case they just used PUCCH for carrying
ACK/NACK for each PDSCH it received. Why
don't we use PDCCH for ACK/NACK on network
side.
PHICH is carried by the first symbol of each sub
frame. (It is located in the same symbol as
PCFICH).
One PHICH is carried by multiple REG.
Multiple PHICH can be carried by the same set
of REG and these multiple PHICH being carried
by the same REGs are called PHICH group.

29. Physical Downlink Shared Channel
(PDSCH)
• Carries user specific data (DL
Payload). Carries Random Access
Response Message. It is using
AMC with QPSK, 16 QAM, 64
QAM, 256 QAM modulation
scheme (This modulation scheme
is determined by MCS that is
carried by DCI)

30. DL Reference Signals: 1 TxAntenna

31. DL Reference Signals: 2 TxAntenna

32. DL Reference Signals: 4 TxAntenna

33. Downlink Transmission –An Example
Example

35. Channel DL Scheduled Operation Overview
IP

36. E-UTRADL Scheduling Principles
• v

37. DLARQ/HARQ Principles

39. https://www.sharetechnote.com/html/Hand
book_LTE_CQI_PMI_RI_ReportingConfigu
ation.html

40. SIB2
RRCConnsetup
https://www.sharetechnote.com/html/Hand
book_LTE_DownlinkPowerAllocation.html
https://www.youtube.com/watc
h?v=YofgiM3s_Zw&ab_chann
el=SmartTelecomEducation

41. Great Thanks