1. LTE RRM introduction & ITRI L3-RRM SW
顏鴻傑
資通所
2015/08/25
Radio Resource Control

2. Outline
RRM concept and key functions
Sample code for RRM development

3. RRM concept and key functions

4. What’s RRM Definition: Goal:
to allocate and manage the limited radio resource to maximize the system performance and capacity.
Goal:
ensure planned QoS of traffic
ensure cell coverage
ensure spectrum utilization

5. LTE features (1/6) RAN structure
Most of RRM functions are located in eNB due to lack of the RRM server (a node to do multi-cell RRM) in E-UTRAN.

6. LTE features (2/6) System bandwidth allocation
E-UTRAN supports 1.4/3/5/10/20 MHz bandwidths, while UTRAN FDD supports only 5MHz bandwidth.
RRM is concerned that different bandwidths lead to different available resources and performance in frequency-selective scheduling.

7. LTE features (3/6) Multiple access techniques
CDMA in UTRAN: both intra-cell and inter-cell UEs may generate interference.
OFDMA/SC-FDMA in downlink/uplink in E-UTRAN: only inter-cell interference.

8. LTE features (4/6) Multiple antenna techniques
LTE supports many MIMO modes and can dynamical switching among them.
Physical resources in space dimension are different in the MIMO modes.

9. LTE features (5/6) Optimization of PS domain
No CS domain in LTE. All traffic in PS domain are packets (i.e., variable length, bursty) and are defined by different parameters compared to CS domain. The parameters of each traffic are determined by many RRM processes.

10. QoS Class Identifier (QCI)

11. LTE features (6/6) Share channel
No dedicated channel in LTE. All traffic share the physical resources which are allocated by packet scheduler.
Specifically, eNB tells the UE the transmission resources (via control signaling) and takes back them when transmission completed.
Packet scheduler in UMTS is constrained by the dedicated channel design.

12. LTE Interface for RRM

13. RRM key functions
(Source: 3GPP TS )

14. Radio Admission Control
RAC purpose: to admit or reject establishment requests for new radio bearers.
RAC goal: to ensure high radio resource utilization by accepting radio bearer requests if radio resources are available. This simultaneously ensures proper QoS for in-progress sessions by rejecting radio bearer requests when they cannot be accommodated.

15. RAC process RAC is triggered when
UE requests serving eNB to do RRC Connection establishment (i.e. add SRB configuration)
MME requests serving eNB to do ERAB setup/modification (i.e. add/change DRB configuration such as QoS info)
Source eNB requests target eNB to do handover preparation (i.e. add SRB and DRB configuration)

16. RAC process Example: bearer setup
(Source: LONG TERM EVOLUTION: 3GPP LTE Radio and Cellular Technology, Auerbach Publications, 2009)

17. RAC process
(Source: LONG TERM EVOLUTION: 3GPP LTE Radio and Cellular Technology, Auerbach Publications, 2009)

18. Radio Bearer Control
RBC involves the establishment, maintenance and release of radio bearers.
RBC is also concerned with the maintenance of radio bearers of in-progress sessions at the change of the radio resource situation due to mobility and so on.
RBC is involved in the release of radio resources associated with radio bearers including at-session termination and handover.

19. RBC process
When?

20. RBC process

21. RBC 提供 DRA 的 QoS 參數

22. Connection Mobility Control
CMC oversees the management of radio resources related to idle or connected mode mobility.
In connected mode, handover decisions may be based on UE/eNB measurements, neighbor cell load, traffic distribution, transport, hardware resources, and operator defined policies.

23. CMC process

24. Cell Selection (1/2) Initial Cell Selection
Scan all RF channels in the E-UTRA bands
Only search for the strongest cell on each carrier frequency
Once a suitable cell is found this cell shall be selected
Stored Information Cell Selection
Stored information of carrier frequencies & optionally also information on cell parameters
Cell Selection when leaving RRC_CONNECTED state
According to redirectedCarrierInfo in RRCConnectionRelease if present (left to Redirect topic discusses)

25. Cell Selection (2/2) TS 36.304 – criterion S TS 36.331 – SIB1
q-RxLevMinOffset
receive level
q-RxLevMin
max((p-MAX – 23), 0)
[dB]
[dB]
quality
q-QaulMin-r9
q-QaulMinOffset-r9
From PHY after Layer 1 Filtering, -140 ~ -44 [dBm]
From PHY after Layer 1 Filtering, ~ -3 [dB]
q-RxLevMin in cellSelectionInfo IE in RRC SIB1, -70 ~ -22 [dBM]
q-QualMin-r9 in CellSelectionInfo-v920 IE in RRC SIB1, -34 ~ -3 [dB]
TS – criterion S
TS – SIB1
TS – RSRP mapping & RSRQ mapping
Avoid “ping-pong” between
different PLMNs
q-RxLevMinOffset n cellSelectionInfo IE in RRC SIB1, 1 ~ 8 [dB]
Avoid “ping-pong” between
different PLMNs
q-QualMinOffset-r9 in CellSelectionInfo-v920 IE in RRC SIB1, 1 ~ 8 [dB]
p-MAX in RRC SIB1, -30 ~ 33 [dBm]
Until now, only 1 UE power class defined, it specifies +23 dBm

26. Cell Re-selection Procedure

27. Cell Re-selection (1/7)
Methods to provide cell reselection related information to the UE
System information
RRCConnectionRelease message
Inheriting from another RAT at inter-RAT cell (re)selection
Absolute priority
For inter-frequency & inter-RAT frequency cell reselection only

28. Cell Re-selection (2/7) Step 1. Perform Measurements Intra-frequency
If serving cell Srxlev > SIntraSearchP && Squal > SIntraSearchQ
May not perform intra-freq. measurements
Otherwise
Shall perform intra-freq. measurements
Inter-frequency & Inter-RAT
Inter-freq. or Inter-RAT freq. with higher priority than serving freq.
Shall perform inter-freq. or inter-RAT freq. measurements
Inter-freq. or Inter-RAT freq. with equal or lower priority than serving freq.
If serving cell Srxlev > SnonIntraSearchP && Squal > SnonIntraSearchQ
May not perform inter-freq. or inter-RAT freq. measurements
s-IntraSearchP-r9 or
s-IntraSearch
s-NonIntraSearchP-r9 or
s-NonIntraSearch

29. Cell Re-selection (3/7) Step 2. Criteria (1/2)
Higher priority E-UTRAN frequency than serving frequency
If threshServingLowQ is present in SIB3
A cell fulfils Squal > ThreshX,HighQ during TreselectionEUTRA
More than 1 second has elapsed since the UE camped on the current serving cell
Otherwise
A cell fulfils Srxlev > ThreshX,HighP during TreselectionEUTRA
Lower priority E-UTRAN frequency than serving frequency
Serving cell fulfils Squal < ThreshServing,LowQ && a cell fulfils Squal > ThreshX,LowQ during TreselectionEUTRA
Serving cell fulfils Srxlev < ThreshServing,LowP && a cell fulfils Srxlev > ThreshX,LowP during TreselectionEUTRA
Equal priority E-UTRAN frequency & Intra-frequency
Fulfilling Criterion S during TreselectionEUTRA
threshX-High
threshServingLow
threshX-Low

30. Cell Re-selection (4/7) Step 2. Criteria (2/2) [dB] [dB]
From PHY after Layer 1 Filtering, -140 ~ -44 [dBm]
From PHY after Layer 1 Filtering, ~ -3 [dB]
q-RxLevMin in InterFreqCarrierFreqInfo IE in RRC SIB5, -70 ~ -22 [dBM]
q-QualMin-r9 in InterFreqCarrierFreqInfo IE in RRC SIB5, -34 ~ -3 [dB]
p-MAX in RRC SIB5, -30 ~ 33 [dBm]
Until now, only 1 UE power class defined, it specifies +23 dBm

31. Cell Re-selection (5/7) Step 3. Ranking (1/2)
Intra-frequency: 0 or q-OffsetCell
Inter-frequency: (q-OffsetFreq + q-OffsetCell) or q-OffsetFreq
From PHY after Layer 1 Filtering, -140 ~ -44 [dBm]

32. Cell Re-selection (6/7) Step 3. Ranking (2/2)
t-ReselectionEUTRA in RRC SIB3 or SIB5

33. Handover Procedure

34. L3 Measurement Measurements configuration
In RRC connection reconfiguration
Each UE may have different config

35. L3 Measurement Trigger Type Event Periodical Event A1 Event A2
Event B1 (Inter RAT)
Event B2 (Inter RAT)
Periodical
ReportStrongestCells
ReportCGI
Event
Measurement Report #1
Measurement Report #2
Measurement Report #1
Measurement Report #2
Event condition matched
Event condition matched
timeToTrigger
reportInterval
timeToTrigger
reportInterval
Start point of measurement
reportAmount: r2
reportAmount: r2
ReportStrongdestCells
Measurement Report #1
Measurement Report #2
Measurement Report #3
Measurement Report #4
reportInterval
reportInterval
reportInterval
reportInterval
Start point of measurement
reportAmount: r4
ReportCGI
Measurement Report
Start point of measurement
reportAmount: r1
(always set to r1)

36. Measurement Report 用途 Event Type 用途 A1
Serving becomes better than threshold
關閉量測 A2
Serving becomes worse than threshold
打開量測 A3
Neighbor becomes offset better than serving
Intra/Inter-frequency handover A4
Neighbor becomes better than threshold
Loading balance A5
Serving becomes worse than threshold1 and neighbor becomes better than threshold2
Intra/Inter-frequency handover,

37. Handover Type (1) (2) (3) (4) Intra E-UTRAN HO w/o S-GW relocation
Intra E-UTRAN HO with S-GW relocation
Intra E-UTRAN HO with MME/S-GW relocation
Inter RAT HO

38. Dynamic Resource Allocation
DRA (or Packet Scheduling, PS) allocates and de-allocates resources including buffering and processing resources and resource blocks to user and control plane packets.

39. DRA jobs To determine the available radio resources for NRT bearers.
NRT: non real-time (a.k.a. non-GBR in LTE)
To determine the available radio resources for NRT bearers.
To share the available radio resources between NRT bearers.
To monitor the allocations for NRT bearers.
To monitor the system loading.
To perform load control actions for NRT bearers (optional).

40. Basic scheduling policy
Round Robin (RR):
Channel condition is not taken into account.
Max Carrier-to-Interference (C/I)
User with the best channel quality is scheduled.
Proportional Fair (PF)
Short-term channel variations are exploited while maintaining long-term average user data rate.
Algorithm
Throughput
Fairness
Complexity
Channel tracking
QoS guarantee RR
low
best no
Max C/I
highest
bad
middle
yes PF
higher
better

41. L2 Scheduler framework Protocol stack (DL process) (UL process)
(per UE/bearer)
(DL process)
(per TTI, per UE)
(scrambled by RNTI)
(per PRB, per TTI)
Upper scheduler
(UL process)
(per TTI, per UE)
Lower scheduler
(scrambled by RNTI)
(per PRB, per TTI)
(MAC signaling)
(Source: LONG TERM EVOLUTION: 3GPP LTE Radio and Cellular Technology, Auerbach Publications, 2009)

42. Load balancing
Task: to balance traffic load over multiple inter-frequency and inter-RAT cells.
Vertical v.s. horizontal LB:
LB among (geographically) overlapped cells
LB among neighbor cells

43. Load balancing 處理 eNBs 常規性的負載 保持無線資源的高度利用 保證已存在的連線的QoS 維持較低的通話遺失率
Overload indication
RAC
CMC
處理 eNBs 常規性的負載
保持無線資源的高度利用
保證已存在的連線的QoS
維持較低的通話遺失率 調整
Handover (
Handover )
threshold LB 調整
Cell re -
CMC
selection 參數 (
Cell re -
LB 的主要目的
selection ) LB
與其他
RRM
模組的關係

44. Load balancing
Intra-LTE considerations: resource utilization, hardware load, transport layer load.
Inter-RAT considerations: available resource, maximum throughput, maximum UE number
other considerations: UE capability, current traffic status, subscriber’s priority,…

45. Inter-Cell Interference Coordination
ICIC manages radio resource blocks to keep inter-cell interference under control, based on the feedback from multiple cells.
Multi-cell RRM approach: to takes into account resources and loads situation in multiple cells

46. Sample code for RRM development – ENBD

47. ENBD module decomposition
Config. & CLI
RRM
RRC
handler
X2AP handler
S1AP handler
User data forwarding
Gateway/NAT
(raw socket)
Serving eNB (RRC)
Neighbor eNB
MME
Serving eNB (PDCP)
Control-plane data
User-plane data

48. Software component (1/5)
RRM
Core RRM function development.
Source files:
enbd\src\rrm\
RRC handler
Handle interaction of RRM with RRC about cell and UE control procedure.
enbd\src\rrc\
RRC interface files:
enbd\src\rrc\new\

49. Software component (2/5)
S1AP handler
Handle interaction of RRM with S1AP about cell and UE control procedure.
Source files:
enbd\src\s1ap\
X2AP handler
Handle interaction of RRM with X2AP about cell and UE control procedure.
enbd\src\x2ap\

50. Software component (3/5)
User data forwarding
Route user data from PDCP to LAN gateway and vice versa (on a per bearer basis).
Source files:
enbd\src\gtpu\
Connection database
Maintain UE and its bearer contexts (shared among all components).
enbd\src\connection\

51. Software component (3/5)
Neighbor database
Maintain neighbor cell contexts (shared among all components).
Source files:
enbd\src\nbr\
Config & CLI
Config: load software/cell/UE common parameters when ENBD software startup (called by main function).
CLI: implement user input command to dynamic configure parameters or trigger procedures.
enbd\enbd\
*CLI: Command-line interface

52. Software component (5/5)
Other libraries:
Raw socket wrapper:
enbd\src\drv\
Common & Sys lib:
enbd\src\

53. RAC development
Case 1: UE requests serving eNB to do RRC Connection establishment (i.e. add SRB configuration) UE
RRC
RRM
MME
random access
RRCConnectionRequest
1. RRC_CON_IND
RAC
2. RRC_CON_SETUP_REQ
RRCConnectionSetup
RRCConnectionSetupComplete
3. RRC_CON_SETUP_CFM
4. S1AP_INIT_UE_MSG

54. RAC development Case 1: Call flow (1/2) rrm_process_prim()
rrc_receive()
prim_UeAdmission
rrc_process_lower()
rrm_process_UeAdmission()
1. RRC_CON_IND
rrc_cell_process_ConnSetup_requested()
rrc_process_prim()
prim_UeAdmission
prim_ConnSetupReq
rrc_ctx_send_rrmprim()
rrc_cell_process_rrm()
rrc_cell_create_ConnSetup()
2. RRC_CON_SETUP_REQ
rrc_send()

55. RAC development Case 1: Call flow (2/2) rrc_receive()
s1ap_receive_prim()
prim_InitConn
rrc_process_lower()
s1ap_client_process_rrm()
3. RRC_CON_SETUP_CFM
rrc_cell_process_ConnSetup_confirmed()
s1ap_client_create_InitUeMsg()
prim_InitConn
4. S1AP_INIT_UE_MSG
rrc_ctx_send_s1prim()
s1ap_send()

56. 2. RRC_CON_RECONFIG_REQ
RAC development
Case 2: MME requests serving eNB to do ERAB setup/modification (i.e. add/change DRB configuration such as QoS info) UE
RRC
RRM
MME
1. S1AP_INIT_CTX_SETUP_REQ
RAC + RBC
2. RRC_CON_RECONFIG_REQ
RRCConnectionReconfiguration
w/ MeasConfig
RRCConnectionReconfigurationComplete
3. RRC_CON_RECONFIG_CFM
4. S1AP_INIT_CTX_SETUP_RSP

57. RAC development Case 2: Call flow (1/3) rrc_receive() s1ap_receive()
rrc_process_prim()
prim_SetupConn
rrc_process_lower()
s1ap_process_sctp()
rrc_cell_process_rrm()
1.2 RRC_SEC_ACTV_CFM
1. S1AP_INIT_CTX_SETUP_REQ
rrc_cell_process_SecActv_confirmed()
s1ap_client_process_sctp()
rrc_cell_create_SecActvReq()
prim_SetupConnAck
prim_SetupConn
1.1 RRC_SEC_ACTV_REQ
rrc_cell_create_UeCapReq()
s1ap_ctx_send_prim()
rrc_send()
1.3 RRC_UE_CAP_REQ
rrc_send()

58. RAC development Case 2: Call flow (2/3) rrm_process_prim()
rrc_receive()
prim_AddDrb
rrm_process_AddBearer()
rrc_process_lower()
1.4 RRC_UE_CAP_CFM
rrc_process_prim()
rrc_cell_process_UeCap_confirmed()
prim_AddDrbAck
prim_AddBearer
rrc_cell_process_rrm()
rrc_ctx_send_internal()
rrc_cell_create_ConnReconfigReq()
2. RRC_CON_RECONFIG_REQ
rrc_send()

59. RAC development Case 2: Call flow (2/3) rrc_receive()
s1ap_receive_prim()
prim_SetupConnAck
rrc_process_lower()
s1ap_client_process_rrm()
3. RRC_CON_RECONFIG_CFM
rrc_cell_process_ConnReconf_confirmed()
s1ap_client_create_InitCtxSetupRsp()
prim_SetupConnAck
4. S1AP_INIT_CTX_SETUP_RSP
rrc_ctx_send_s1prim()
s1ap_send()

60. RAC development
Case 3: Source eNB requests target eNB to do handover preparation (i.e. add SRB + DRB config)
Source eNB UE
RRC
RRM
MME
1. X2AP_HO_REQ
2. RRC_HO_PREPAR_REQ
3. RRC_HO_PREPAR_CFM
RAC + RBC
4. RRC_HO_RSV_REQ
5. RRC_HO_RSV_CFM
6. X2AP_HO_REQ_ACK
RRCConnectionReconfiguration
(MobilityInfo of target cell)
RRCConnectionReconfigurationComplete
7. RRC_HO_CFM_IND
8. S1AP_PS_REQ
9. S1AP_PS_RSP
10. RRC_HO_PS_IND
11. X2AP_UE_RELEASE

61. RAC development Case 3: Call flow (1/5) x2ap_receive()
rrc_process_prim()
prim_SetupHoConn
x2ap_process_sctp()
rrc_cell_process_rrm()
1. X2AP_HO_REQ
rrc_cell_create_HoPrepReq()
x2ap_client_process_sctp()
prim_SetupHoConn
2. RRC_HO_PREPAR_REQ
x2ap_ctx_send_prim()
rrc_send()

62. RAC development Case 3: Call flow (2/5) rrm_process_prim()
rrc_receive()
prim_HoAdmission
rrm_process_HoAdmission()
rrc_process_lower()
3. RRC_HO_PREPAR_CFM
rrc_process_prim()
rrc_cell_process_HoPrep_confirmed()
prim_HoAdmissionAck
prim_HoAdmission
rrc_cell_process_rrm()
rrc_ctx_send_internal()
rrc_cell_create_HoRsvReq()
4. RRC_HO_RSV_REQ
rrc_send()

63. RAC development Case 3: Call flow (3/5) rrc_receive()
x2ap_receive_prim()
prim_SetupHoConnAck
rrc_process_lower()
x2ap_client_process_rrm()
5. RRC_HO_RSV_CFM
rrc_cell_process_HoRsv_confirmed()
x2ap_peer_create_HoReqAck()
prim_SetupHoConnAck
6. X2AP_HO_REQ_ACK
rrc_ctx_send_x2prim()
x2ap_send()

64. RAC development Case 3: Call flow (4/5) rrc_receive()
s1ap_receive_prim()
prim_PathSwitch
rrc_process_lower()
s1ap_client_process_rrm()
7. RRC_HO_CFM_IND
rrc_cell_process_HoCmp_confirmed()
s1ap_client_create_PsReq()
prim_PathSwitch
8. S1AP_PS_REQ
rrc_ctx_send_s1prim()
s1ap_send()

65. RAC development Case 3: Call flow (5/5) s1ap_receive()
rrc_process_prim()
x2ap_receive_prim()
prim_PathSwitchAck
prim_UeRelease
s1ap_process_sctp()
rrc_cell_process_rrm()
x2ap_client_process_rrm()
9. S1AP_PS_RSP
s1ap_client_process_sctp()
rrc_cell_create_PsInd()
x2ap_peer_create_UeRelease()
prim_PathSwitchAck
10. RRC_HO_PS_IND
11. X2AP_UE_RELEASE
s1ap_ctx_send_prim()
rrc_send()
x2ap_send()
prim_UeRelease
rrc_ctx_send_x2prim()

66. 2. RRC_CON_RECONFIG_REQ
RBC development
Case 1: MME requests serving eNB to do ERAB setup (i.e. add DRB configuration such as QoS info) UE
RRC
RRM
MME
1. S1AP_ERAB_SETUP_REQ
RAC + RBC
2. RRC_CON_RECONFIG_REQ
RRCConnectionReconfiguration
RRCConnectionReconfigurationComplete
3. RRC_CON_RECONFIG_CFM
4. S1AP_ERAB_SETUP_RSP

67. RBC development Case 1: Call flow (1/2) rrm_process_prim()
s1ap_receive()
prim_AddDrb
rrm_process_AddBearer()
s1ap_process_sctp()
1. S1AP_ERAB_SETUP_REQ
rrc_process_prim()
s1ap_client_process_sctp()
prim_AddBearerAck
rrc_cell_process_rrm()
prim_AddDrb
s1ap_ctx_send_prim()
rrc_cell_create_ConnReconfigReq()
2. RRC_CON_RECONFIG_REQ
rrc_send()

68. RBC development Case 1: Call flow (2/2) rrc_receive()
s1ap_receive_prim()
prim_AddBearerAck
rrc_process_lower()
s1ap_client_process_rrm()
3. RRC_CON_RECONFIG_CFM
rrc_cell_process_ConnReconf_confirmed()
s1ap_client_create_ErabSetupRsp()
prim_AddBearerAck
4. S1AP_ERAB_SETUP_RSP
rrc_ctx_send_s1prim()
s1ap_send()

69. 2. RRC_CON_RECONFIG_REQ
RBC development
Case 2: MME requests serving eNB to do ERAB modify (i.e. change DRB configuration) UE
RRC
RRM
MME
1. S1AP_ERAB_MOD_REQ
(RAC) + RBC
2. RRC_CON_RECONFIG_REQ
RRCConnectionReconfiguration
RRCConnectionReconfigurationComplete
3. RRC_CON_RECONFIG_CFM
4. S1AP_ERAB_MOD_RSP

70. RBC development Case 2: Call flow (1/2) rrm_process_prim()
s1ap_receive()
prim_ModBearer
rrm_process_ModifyBearer()
s1ap_process_sctp()
1. S1AP_ERAB_MOD_REQ
rrc_process_prim()
s1ap_client_process_sctp()
prim_ModBearerAck
prim_ModBearer
rrc_cell_process_rrm()
s1ap_ctx_send_prim()
rrc_cell_create_ConnReconfigReq()
2. RRC_CON_RECONFIG_REQ
rrc_send()

71. RBC development Case 2: Call flow (2/2) rrc_receive()
s1ap_receive_prim()
prim_ModBearerAck
rrc_process_lower()
s1ap_client_process_rrm()
3. RRC_CON_RECONFIG_CFM
rrc_cell_process_ConnReconf_confirmed()
s1ap_client_create_ErabModRsp()
prim_ModBearerAck
4. S1AP_ERAB_MOD_RSP
rrc_ctx_send_s1prim()
s1ap_send()

72. 2. RRC_CON_RECONFIG_REQ
RBC development
Case 3: MME requests serving eNB to do ERAB release (i.e. delete DRB configuration). RBC may adjust other DRBs as well. UE
RRC
RRM
MME
1. S1AP_ERAB_REL_CMD
RBC
2. RRC_CON_RECONFIG_REQ
RRCConnectionReconfiguration
RRCConnectionReconfigurationComplete
3. RRC_CON_RECONFIG_CFM
4. S1AP_ERAB_REL_RSP

73. RBC development Case 3: Call flow (1/2) rrm_process_prim()
s1ap_receive()
prim_RelBearer
s1ap_process_sctp()
rrm_process_ReleaseBearer()
1. S1AP_ERAB_REL_CMD
rrc_process_prim()
s1ap_client_process_sctp()
prim_RelBearer
prim_RelBearerAck
rrc_cell_process_rrm()
s1ap_ctx_send_rrmprim()
rrc_cell_create_ConnReconfigReq()
2. RRC_CON_RECONFIG_REQ
rrc_send()

74. RBC development Case 3: Call flow (2/2) rrc_receive()
s1ap_receive_prim()
prim_RelBearerAck
rrc_process_lower()
s1ap_client_process_rrm()
3. RRC_CON_RECONFIG_CFM
rrc_cell_process_ConnReconf_confirmed()
s1ap_client_create_ErabRelRsp()
prim_RelBearerAck
4. S1AP_ERAB_REL_RSP
rrc_ctx_send_s1prim()
s1ap_send()

75. CMC-HO development
Part 1: Source eNB may setup/modify/remove L3 measurement configurations for the UE dynamically. UE
RRC
RRM
L3_MEAS
1. RRC_CON_RECONFIG_REQ
RRCConnectionReconfiguration
RRCConnectionReconfigurationComplete
2. RRC_CON_RECONFIG_CFM
loop
MeasurementReport
3. RRC_MEAS_REPORT_IND

76. CMC-HO development Part 1: Call flow (1/2) 1. RRC_CON_RECONFIG_REQ
rrc_receive()
rrm_cmc_evaluate_MeasConfig()
rrc_process_lower()
rrc_process_prim()
2. RRC_CON_RECONFIG_CFM
prim_MeasConfig
rrc_cell_process_rrm()
rrc_cell_process_ConnReconf_confirmed()
rrc_cell_create_ConnReconfigReq()
1. RRC_CON_RECONFIG_REQ
rrc_send()

77. CMC-HO development Part 1: Call flow (2/2) rrc_receive()
rrc_process_lower()
3. RRC_MEAS_REPORT_IND
rrc_cell_process_ConnReconf_confirmed()
prim_MeasReport
rrc_ctx_send_internal()

78. CMC-HO development
Part 2: Source eNB make handover decision (i.e., choose the target cell for the UE to be hand-off).
Target eNB UE
RRC
RRM
HO decision
1. RRC_HO_INFO_REQ
2. RRC_HO_INFO_CFM
3. X2AP_HO_REQ
4. X2AP_HO_REQ_ACK
5. RRC_HO_CMD_REQ
(w/ RRCConnectionReconfiguration)
RRCConnectionReconfiguration
6. RRC_HO_CMD_CFM
RRCConnectionReconfigurationComplete
7. X2AP_UE_RELEASE
8. RRC_CON_REL_REQ
9. RRC_CON_REL_CFM

79. CMC-HO development Part 2: Call flow (1/4) rrc_receive()
rrm_cmc_evaluate_HoConfig()
rrc_process_lower()
rrc_process_prim()
2. RRC_HO_INFO_CFM
prim_HoRequired
rrc_cell_process_rrm()
rrc_cell_process_HoInfo_confirmed()
prim_PrepHoConn
rrc_cell_create_HoInfoReq()
rrc_ctx_send_x2prim()
1. RRC_HO_INFO_REQ
rrc_send()

80. CMC-HO development Part 2: Call flow (2/4) x2ap_receive_prim()
prim_PrepHoConn
x2ap_process_sctp()
x2ap_client_process_rrm()
4. X2AP_HO_REQ_ACK
x2ap_peer_create_HoReq()
x2ap_client_process_sctp()
3. X2AP_HO_REQ
prim_PrepHoConnAck
x2ap_send()
x2ap_ctx_send_prim()

81. CMC-HO development Part 2: Call flow (3/4) 5. RRC_HO_CMD_REQ
rrc_receive()
rrc_process_prim()
prim_PrepHoConnAck
rrc_process_lower()
rrc_cell_process_rrm()
6. RRC_HO_CMD_CFM
rrc_cell_create_HoCmdReq()
rrc_cell_process_HoCmd_confirmed()
5. RRC_HO_CMD_REQ
prim_PrepHoConn
rrc_send()
rrc_ctx_send_x2prim()

82. CMC-HO development Part 2: Call flow (4/4) rrc_receive()
x2ap_receive()
rrc_process_prim()
rrc_process_lower()
prim_UeRelease
x2ap_process_sctp()
rrc_cell_process_rrm()
9. RRC_CON_REl_CFM
7. X2AP_UE_RELEASE
rrc_cell_process_ConnReL_confirmed()
x2ap_client_process_sctp()
rrc_cell_create_ConnRelReq()
prim_UeRelease
8. RRC_CON_REL_REQ
x2ap_ctx_send_prim()
rrc_send()

83. CMC-Idle development
For UE cell reselection: (re-)configure cell broadcast info (i.e., SIB3 and SIB4/SIB5 parameters).
RRC
RRM
CMC-Idle
1. RRC_SIB3_CFG_REQ
2. RRC_SIB3_CFG_CFM
option
3. RRC_SIB4_CFG_REQ
4. RRC_SIB4_CFG_CFM
option
5. RRC_SIB5_CFG_REQ
6. RRC_SIB5_CFG_CFM

84. CMC-Idle development Call flow 1. RRC_SIB3_CFG_REQ rrc_receive()
rrm_cmc_evaluate_CellCofig()
rrc_process_lower()
rrc_process_prim()
2. RRC_SIB3_CFG_CFM
prim_CellReconfig
rrc_cell_process_rrm()
rrc_cell_process_Sib3_confirmed()
rrc_cell_process_CellReconfig_requested()
rrm_cell_pack_cellSetup()
1. RRC_SIB3_CFG_REQ
rrc_send()

85. LB development load control for idle UE load control for connected UE:
Configure SIB (similar to CMC-Idle).
load control for connected UE:
Reject lower priority UE/RB during RAC procedure.
Configure CMC-HO threshold.

86. L2 measurement eNB L2 measurement provisioning
MAC provides cell-level load info to assist LB (and RAC/CMC as well) on demand.
RRC
RRM
RRC_L2_MEAS_REQ
(type=PRB_USAGE, interval=T)
Interval=T
RRC_L2_MEAS_IND

87. Thanks for your time. We hope this introduction is helpful.