LTE Study

1. 1. S1AP Setup Request Message : eNBMME (S1AP- Management messages)
To transfer information for a TNL (Transport Network Layer) association
1
Global-ENB-ID
2
eNB Name
3
Supported TAs
4
CSG Id List
5
Default paging DRX
This information element is used to globally identify an eNB
PLMN Identity, Macro eNB, Home eNB
PrintableString
Supported TAs in the eNB
TAC,Broadcast PLMNs(PLMN Identity),
Supported maxnoofCSGIds
CSG(Closed Subscriber Group) Id
ENUMERATED(32, 64, 128, 256)
M
O
M
M
M
2. S1AP Setup Response Message :MMEeNB (S1AP- Management messages)
To transfer information for a TNL (Transport Network Layer) association
1
MME Name
2
Served GUMMEIs
3
RelativeMMECapacity
4
CriticalityDiagnostics
PrintableString
The LTE related pool configuration is included on the first
place in the list.
Served PLMNs(PLMN Identity),Served GroupIDs(MME
Group Id)
Relative processing capacity of an MME with respect to the
other MMEs in the pool in order to load-balance MMEs
within a pool (0 to 255)
Sent by the eNB or the MME when parts of a received
message have not been comprehended or were missing, or if
the message contained logical errors
ProcedureCode,TriggeringMessage,Criticality,CriticalityDiag
nostics-IE-List,ProtocolExtensionContainer
O
M
M
O
If the S1 SETUP FAILURE messages include the Time To Wait IE the eNB shall wait at least
for the indicated time before reinitiating the S1 setup towards the same MME.
If the eNB initiates the procedure by sending a S1 SETUP REQUEST message including the
PLMN Identity IEs and none of the PLMNs provided by the eNB is identified by the MME, then
the MME shall reject the eNB S1 Setup Request procedure with the appropriate cause value e.g
"Unknown PLMN".
3. RRC connection Request: UE E-UTRAN (RRC Connection Establishment
Messages)
To establish an RRC connection.RRC connection establishment involves SRB1 establishment at
RRC_IDLE state.
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2. Also used to transfer the initial NAS dedicated information/ message from the UE to E-UTRAN.
UE sets the UE-Id, if upper layer provide S-TMSI-Temporary Mobile Subscriber Identity (The
temporary UE identity provided by the MME which uniquely identifies the UE within the
tracking area) then UE set the UE-Id as S-TMSI else UE will draw a random value and sets as
UE-Id.
1
ue-Identity
2
establishmentCause
4.
To identify the UE in the contention based access at RRC
connection establishment
s-TMSI, randomValue
emergency, highPriorityAccess, mt-Access, mo-Signalling,
mo-Data
M
M
RRC Connection Setup: E-UTRAN UE (RRC Connection Establishment
Messages)
To establish an RRC connection setup involves SRB1 establishment at RRC_CONNECTED
state.
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3. MIB-Master Information Block (E UTRAN  UE) Fixed schedule of 40msec
RLC Mode-TM, Logical Channel: BCCH, Transport Channel: BCH, IDLE and CONNECTED
Every 4 frames starting from SFN 0, SFN 4, SFN 8, SFN 12, SFN 16 (SFN mod 4)
A limited number of most essential and most frequently transmitted parameters that are needed
acquire other information from the cell.
The MIB contains
1. DL bandwidth of the cell-n6, n15, n25, n50, n75, n100 (6 RB,15RB etc)
2. PHICH configuration
a. PHICH-Duration-Normal, Extended
b. PHICH-Resource-1/6,1/2,1,2
3. System Frame Number (SFN)
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4. SIB1-System Information Block 1 (E UTRAN  UE) Fixed schedule of 80msec
RLC Mode-TM, Logical Channel: BCCH, Transport Channel:
CONNECTED
DL-SCH, IDLE and
Every 8 frames starting from SFN 0, SFN 8, SFN 16 (SFN mod 8)
Contains information relevant when evaluating if a UE is allowed to access a cell and defines the
scheduling of other system information
The SIB1 contains
1. CellAccessRelatedInfo
a. PLMN-IdentityList- List of PLMN identities. The first listed PLMN-Identity is
the primary PLMN
b. TrackingAreaCode- A trackingAreaCode that is common for all the PLMNs listed
c. CellIdentity- Identity of the cell
d. CellBarred- 'barred’ means the cell is barred
e. IntraFreqReselection- Used to control cell reselection to intra-frequency cells
when the highest ranked cell is barred, or treated as barred by the UE
f. csg-Indication- If set to TRUE the UE is only allowed to access the cell if the
CSG identity matches an entry in the allowed CSG list that the UE has stored.
g. csg-Identity- Identity of the Closed Subscriber Group within the primary PLMN
the cell belongs to. This field is present in a CSG cell
2. cellSelectionInfo
a. Q-RxLevMin
b. q-RxLevMinOffset
3. p-Max- Maximum power value applicable for the cell. If this IE is absent, then the
UE applies the maximum power according to the UE capability
4. freqBandIndicator- Operating frequency band of the cell
5. schedulingInfoList
a. si-Periodicity- Periodicity of the SI-message in radio frames, such that rf8
denotes 8 radio frames, rf16 denotes 16 radio frames, and so on
b. sib-MappingInfo- List of the SIBs mapped to this System Information
message. There is no mapping information of SIB2; it is always present in the
first System Information message listed in the schedulingInfoList list
6. tdd-Config-Present for only TDD if present for FDD UE shall delete this value
7. si-WindowLength- Common SI scheduling window for all SIs. Unit in milliseconds,
where ms1 denotes 1 millisecond, ms2 denotes 2 milliseconds and so on.
8. systemInfoValueTag- Common for all SIBs other than MIB, SIB1, SIB10, SIB11 and
SIB12. Change of MIB and SIB1 is detected by acquisition of the corresponding
message
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5. 5

6. SIB 2-System Information Block 2 (E UTRAN  UE) Determine by 1st SI-160msec
RLC Mode-TM, Logical Channel: BCCH, Transport Channel:
CONNECTED
DL-SCH, IDLE and
Contains radio resource configuration information that is common for all UEs
The SIB2 contains
1. ac-BarringInfo(Access Class)
a. Emergency
b. Mobile originating Signaling
c. Mobile originating Data
2. RadioResourceConfigCommonSIB- The IE RadioResourceConfigCommonSIB is used to
specify common radio resource configurations e.g., the random access parameters and the
static physical layer parameters
3. UE-TimersAndConstants
a. T300- RRCConnectionRequest-> RRCConnectionSetup or RRCConnectionReject
b. T301- RRCConnectionReestabilshmentRequest->
RRCConnectionReestablishment or RRCConnectionReestablishmentReject and
Goes to RRC_IDLE State
c. T302- RRCConnectionReject-> RRC_CONNECTED and upon cell re-selection
d. T303- Access barred while performing RRC connection establishment for mobile
originating calls-> RRC_CONNECTED and upon cell re-selection
e. T304- RRCConnectionReconfiguration-> successful completion of handover to
EUTRA
f. T305- RRC connection establishment for mobile originating signaling->
RRC_CONNECTED and upon cell re-selection
g. T310- Upon detecting physical layer problems-> receiving N311 consecutive insync indications from lower layers
h. T311- Initiating the RRC connection re-establishment procedure-> Selection of a
suitable E-UTRA cell or a cell using another RAT
i. T320- upon cell (re)selection to E-UTRA from another RAT with validity time
configured for dedicated priorities-> RRC_CONNECTED, when PLMN selection
is performed on request by NAS, or upon cell (re)selection to another RAT
j. T321- Upon receiving measConfig including a reportConfig with the purpose set
to reportCGI-> Upon acquiring the information needed to set all fields of
cellGlobalId for the requested cell
k. N310 Maximum number of consecutive "out-of-sync" indications received from
lower layers
l. N311 Maximum number of consecutive "in-sync" indications received from
lower layers
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7. 4. freqInfo
a. ul-CarrierFreq
b. ul-Bandwidth
5. MBSFN-SubframeConfigList
6. TimeAlignmentTimer
Channels in LTE
In order to carry information from one layer to other, or, from one entity to other entity. This is
applicable to the Protocol stack or between UE and eNB.
The Protocol Stack of UE and the associated channels are mentioned below:
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8. UE Protocol Stack
RLC uses Logical channels to transfer information to the MAC and lower layers; similarly, the
MAC layer uses the Logical channels to transfer information to RLC and upper layers.
MAC uses Transport channels to transfer information to the PHY and lower layers; similarly, the
PHY layer uses the Transport channels to transfer information to MAC and upper layers.
The PHY layer uses the Physical Channels in order to transfer information on the Air Interface.
All the above channels have Downlink and Unlink purposes; which means that when the
information is being transferred from the eNB to UE Downlink Channels are used.
Similarily, Uplink channels are used when information is passed from UE to eNB.
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9. The below table lists the LTE channels for DL and UL:
Physical DL Channels
Physical broadcast channel (PBCH)
Physical control format indicator channel (PCFICH)
Physical downlink control channel (PDCCH)
Physical downlink shared channel (PDSCH)
Physical multicast channel (PMCH)
Physical Hybrid ARQ Indicator Channel (PHICH)
Physical UL Channels
Physical uplink control channel (PUCCH)
Physical uplink shared channel (PUSCH)
Physical random access channel (PRACH)
Transport DL Channels
Broadcast Channel (BCH)
Downlink Shared Channel (DL-SCH)
Paging Channel (PCH)
Multicast Channel (MCH)
Transport UL Channels
Uplink
Shared
Channel
(UL-SCH)
Random Access Channel(s) (RACH)
Logical Control Channels
Broadcast
Control
Channel
Paging
Control
Channel
Common
Control
Channel
Multicast
Control
Channel
Dedicated Control Channel (DCCH)
Logical Traffic Channels
(BCCH) Dedicated
Traffic
Channel
(DTCH)
(PCCH) Multicast Traffic Channel (MTCH)
(CCCH)
(MCCH)
Downlink Channels
The below diagram depicts the association of LTE Downlink Channels:
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10. LTE Downlink Channels
Each channel has a specific role to play and the functions of each channel are mentioned below:
1. Downlink Logical Channels:
a.
b.
c.
d.
e.
f.
g.
PCCH: used for paging the UE
BCCH: Used for broadcasting MIBs/SIBs
CCCH: Common to multiple UE's
DCCH: used to transmit dedicated control information for a particular UE
DTCH: Dedicated Traffic for a particular UE
MCCH: used for transmit information for Multicast reception
MTCH: used to transmit Multicast data
2. Downlink Transport Channels:
a. PCH: used for Paging
b. BCH: used for MIB, get mapped to BCCH
c. DL-SCH: used for SIB, data transfer
d. MCH: used for transmitting MCCH information to set up multicast transmissions
3. Downlink Physical Channels:
a.
PBCH: used for transmitting MIB
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11. b. PDSCH: for SIB, data
c. PMCH: Multicast channel
d. PHICH: for HARQ ack/nack status
e. PDCCH: control channel (carries information to UE about the scheduling of PDSCH), UL
grant, Indication for paging, carries HARQ ACK/NACK
Uplink Channels
The below diagram depicts the association of LTE Uplink Channels:
LTE Uplink Channels
1. Uplink Transport Channels:
a.
b.
RACH: used for the initial access to the network (RANDOM ACCESS Procedure)
UL-SCH: used for UL data transfer
2. Uplink Physical Channels:
a.
b.
c.
PRACH: transmit RACH
PUSCH: used for UL data
PUCCH: used for control signaling requirements (SRs, HARQ)
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12. L1-DL Control elements:
1. DCI- Downlink Control Indicator
a. Which resource block carries data, what kind of demodulation scheme we have to
use to decode data?
b. Carried by PDCCH.
c. The following formats will be used.
Format 0
UL Grant. (Resource Allocation for PUSCH)
Format 1
Transmission of PDSCH for SIMO operation
Format 1A Resource Allocation for SIMO DL PDSCH and UL Power Control
Format 1B
Transmission control information of MIMO Rank 1 based compact
resource assignment
Format 1C
Very compact type of resource allocation for PDSCH
Format 1D Same as format 1B with additional information of power offset
Format 2
DL MIMO Closed Loop and UL Power Control
Format 2A DL MIMO Open Loop and UL Power Control
Format 3
UL Power Control Only (for multiple UEs)
Format 3A UL Power Control Only (for multiple UEs)
2. CFI- Control Format Indicator
a. How many OFDM symbols are used for carrying PDCCH at each subframe
b. Carried by PCFICH
1. CFI1
2. CFI2
3. CFI3
4. CFI4 -Reserved
3. HI-HARQ Indicator
a. HARQ indicator is used indicate a positive acknowledgement (ACK) or negative
acknowledgement (NACK) for data sent using the uplink shared channel.
b. Carried by PHICH
1. HI= ‘0' represents a NACK
2. HI=‘1' represents an ACK.
L1-UL Control elements:
1. CQI- Channel Quality Indicator
a. Carrying the information on how good/bad the communication channel
quality
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13. b. The following factors will be used for calculating the Channel quality.
1. signal-to-noise ratio (SNR)
2. signal-to-interference plus noise ratio (SINR)
3. signal-to-noise plus distortion ratio (SNDR)
c. CQI is carried by PUCCH or PUSCH depending on the situation as follows.
1. Carried by PUCCH : When there is no uplink data to be transmitted
2. Carried by PUSCH: When there is uplink data to be transmitted.
d. The following tables mapping of 4-bit CQI with Modulation.
2. SR- Scheduling Request
a. Scheduling radio resource for uplink transmission by the UE to the Enb
b. UE send SR on PUCCH when regular BSR (Buffer status report) is triggered
and UE does not have radio resource to transmit this BSR to eNB.
c. Carried by PUCCH
3. HI- HARQ Indicator
d. HARQ indicator is used indicate a positive acknowledgement (ACK) or
negative acknowledgement (NACK) for data sent using the downlink shared
channel.
e. Carried by PUCCH
1. HI= ‘0' represents a NACK
2. HI=‘1' represents an ACK.
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