lte signaling radio bearer
TRANSCRIPT
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2.LTE Signaling Radio Bearer Overview
MobileComm Professionals, Inc Author : Ray KhasturTitle : LTE Optimization Consultant
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2.1 Bearer Overview
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What is Bearer ?
“Bearer” is the way how packet data transmitted from the UE until the Internet Cloud area. In another word Bearer is the pipeline that pass through the communication content which can be transform from one pipeline to another pipeline. As we can see on above picture that during the transmission of internet content via LTE Networks called as EPS Bearer (Evolved Packer System). Out side LTE environment called as External Bearer.
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Bearer Components
If you see the diagram shown above, you would notice that this bearer has two main part. One is 'Radio Bearer' and the other part is Core network bearer.In LTE, the both 'Radio Bearer' part and 'Core Network Bearer' both configured by a single message, 'RRC Connection Reconfiguration'. Actually within 'RRC Connection Reconfiguration' message there is one part for Radio configuration and another part for Core Network configuration.
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2.2 Type of Radio Bearer
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Type of EPS Bearer
i) Default EPS Bearer :Be established during Attach ProcessAllocate IP address to UEDoes not have specifc QoS (only Nominal QoS is applied).Similar to Primary PDP Context in UMTS
ii) Dedicated EPS BearerNormally be established during the call setup after idle mode. (but can be established during the attach as well).Does not allocate any additional IP address to UEIs linked to a specified default EPS bearerHave a specific (usually guaranteed) QoSSimilar to Secondary PDP Context in UMTS
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• SRB0 is for RRC messages using the CCCH logical channel;
• SRB1 is for RRC messages (which may include a piggybacked NAS
message) as well as for NAS messages prior to the establishment of
SRB2, all using DCCH logical channel;
• SRB2 is for RRC messages which include logged measurement
information as well as for NAS messages, all using DCCH logical
channel. SRB2 has a lower-priority than SRB1 and is always configured
by E-UTRAN after security activation.
Signaling Radio Bearer
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SRB Mapping
• MasterInformationBlock
– Signalling radio bearer:
N/A
– RLC-SAP: TM
– Logical channel: BCCH
– Direction: E-UTRAN to UE
• SystemInformationBlockType1
– Signalling radio bearer:
N/A
– RLC-SAP: TM
– Logical channel: BCCH
– Direction: E-UTRAN to UE
• RRCConnectionRequest
– Signalling radio bearer:
SRB0
– RLC-SAP: TM
– Logical channel: CCCH
– Direction: UE to E-UTRAN
• RRCConnectionSetup
– Signalling radio bearer:
SRB0
– RLC-SAP: TM
– Logical channel: CCCH
– Direction: E-UTRAN to UE
RRCConnectionSetupComplete
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: UE to E-UTRAN
RRCConnectionReconfiguration
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
MeasurementReport
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: UE to E-UTRAN
MobilityFromEUTRACommand
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
UECapabilityEnquiry
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
UEInformationRequest
- Signalling radio bearer: SRB1
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
DLInformationTransfer
- Signalling radio bearer: SRB2 or SRB1 (only if SRB2 not established yet. If SRB2 is suspended, E-UTRAN does not send this message until SRB2 is resumed.)
- RLC-SAP: AM
- Logical channel: DCCH
- Direction: E-UTRAN to UE
Paging
- Signalling radio bearer: N/A
- RLC-SAP: TM
- Logical channel: PCCH
- Direction: E-UTRAN to UE
The RLC (Radio Link Control) layer is responsible for delivery of upper layer SDUs. RLC can work in 3 different modes, depending on the requirement of the data to be transported; Transparent Mode (TM), Unacknowledged Mode (UM) and Acknowledged Mode (AM). AM has functions for retransmission of erroneous received PDUs. The RLC working in UM or AM also has functions for segmentation and concatenation of SDUs sent over the LTE air interface. For received PDUs RLC support functions for re-ordering, duplicate detection and reassembly
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Type of EPS Bearer Cont’d (Attach)
Default EPS Bearer Setup
Dedicated EPS Bearer Setup
This process happen mostly on the Smartphone as additional Bearer Setup after normal attach procedure perform
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Type of EPS Bearer Cont’d (Service Req)
Dedicated EPS Bearer Setup
This process happen after UE Entering RRC Idle State condition. When there are packets data need to be send to this UE. MME will performing Paging Activity to
search and waking up those UE to receive waiting packets data.
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2.3 Function of Radio Bearer
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Bearer Level QoS
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Bearer Level QoS
Default bearer 1: Used for signaling messages (sip signaling) related to IMS network. It uses qci 5
Dedicated bearer: Used for VoLTE VoIP traffic. It uses qci 1 and is linked to default bearer 1
Default bearer 2: Used for all other smartphone traffic (video, chat, email, browser etc), assuming qci 9 is used here
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Traffic – Radio Bearers
o Radio Bearers
The radio bearers KPIs consist of ten sub-KPIs, one is for the total of radio bearers and
the other nine are for nine QCIs. This set of KPIs can be used to evaluate the average
radio bearers in a cell or a cluster. The radio bearer for each QCI is based on the number
of active RRC connections for each QCI according to the QCI defined in the QoS
information.
……
9__QCIrsRadioBeare
1__QCIrsRadioBeare
RadioBearers
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Traffic – Counter Mapping for Radio Bearers
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Traffic - Traffic Volume
o Downlink Traffic Volume
Similar to the radio bearers KPIs, the downlink traffic volume KPIs consist of ten sub-
KPIs, one is for the total of traffic volume for DRBs and the other nine are for nine QCIs.
This group of KPIs can be used to evaluate the DL traffic volume in a cell, which is
measured at the PDCP layer excluding the PDCP header
…… 9__QCIolumeDLTrafficV_ _1DLTrafficVolume QCI
o Uplink Traffic Volume
Similar to the downlink traffic volume KPIs, the uplink traffic volume KPIs consist of ten
sub-KPIs, one is for the total of traffic volume for DRBs and the other nine are for nine
QCIs. This group of KPIs can be used to evaluate the uplink traffic volume in a cell. The
KPIs are measured at the PDCP layer excluding the PDCP header.
1__QCIolumeULTrafficV 9__QCIolumeULTrafficV……
DLTrafficVolume
ULTrafficVolume
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Traffic - Counter Mapping for Traffic Volume
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Traffic - Counter Mapping for Traffic Volume
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Service Integrity – Service Average Throughput
o Service Downlink Average Throughput
This KPI consist of nine sub-KPIs mapped into nine QCIs (QCI 1~9), they evaluate the downlink throughput of a service with a specific QCI per user in each cell, it reflects the end-user experience.
o Service Uplink Average Throughput
Same with the service downlink average throughput, this set of KPIs consist of nine
sub-KPIs mapped into nine QCIs (QCI 1~9), and the meaning is also similar with it.
1__QCIhroughputULAverageT
……
9__QCIhroughputULAverageT
1__QCIhroughputDLAverageT
……
9__QCIhroughputDLAverageT
The total downlink traffic volume at PDCP layer of each QCI and total duration for transmitting them are measured within a measurement period. Then the average throughput of each QCI is obtained at the end of the measurement period.
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Service Integrity – Cell Average Throughput
o Cell Downlink Average Throughput
This KPI evaluates the cell downlink average throughput when there are data transferring
at downlink. It reflects the cell capacity.
The total downlink traffic volume at PDCP layer of cell and total duration for transmitting
which is measured within a measurement period. Then the average throughput of cell is
obtained at the end of the measurement period.
o Cell Uplink Average Throughput
Same with the cell downlink average throughput, this set of KPI reflects the cell
capacity, and the meaning is also similar with it.
CellDLTrafficVolumeCellDLAveThp
CellDLTransferTime
CellULTrafficVolumeCellULAveThp
CellULTransferTime
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Service Integrity – Cell Maximum Throughput
o Cell Downlink Maximum Throughput
This KPI evaluates the cell downlink maximum throughput when there are data
transferring at downlink. It reflects the cell capacity. It is calculated based on maximum
value of downlink traffic volume which are transferred at each second.
o Cell Uplink Maximum Throughput
Same with the cell downlink maximum throughput. It is calculated based on maximum
value of downlink traffic volume which are transferred at each second.
1 ( )
1000( )
CellULMaxTrafficVolumeforEach s bitCellULMaxThp
ms
1 ( )
1000( )
CellDLMaxTrafficVolumeforEach s bitCellDLMaxThp
ms
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Service Integrity – Counter Mapping for Service Average
Throughput
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Application Protocol Identities
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LTE UE States
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Connection Management
UE State
RRC_CONNECTED
ACTIVE SLEEP
RRC_IDLE MODE
Intra Freq Cell Reselection
Inter Freq Cell Reselection
DRX
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Basic State
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Call Processing Procedure
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Full Basic Layer Configuration
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DL Channel Mapping
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UL Channel Mapping
PUSCH 0 PUSCH 1
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Channel Mapping
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Thank You
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Ray Khastur, ST.
Educational Background : Bachelor of Telecommunication Engineer, Telkom Institute of Technology (2006 –2010) JPPA-N Acceleration
Professional Experience : PI.Works, RAN Consultant (2014 ~ Present) China JIESAI, LTE Optimization Consultant (2014) Lintas Media Telekomunikasi, LTE RF Team Leader (2013 ~ 2014) HUAWEI Tech Investment, CWiL RNP/O Engineer (2011 ~ 2013) Transdata Global Network, CDMA RNO Engineer (2010 ~2011)
Achievements : RF Network Design & Planning First Commercial LTE Network in Indonesia (BOLT! Super 4G LTE)-2013 HUAWEI NPI & Post Launch Optimization BOLT! Super 4G LTE - 2014 PI.Works LTE Technical Expert for HUAWEI Environment LTE Planning & Optimization Trainer Floatway Certified-2013 LTE HUAWEI Trainer for Subcont-2016
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