LTE Femto Development Young Hwan Kim

LTE high level requirements per Reduced cost per bit –improved spectrum efficiency = 3~4 times in DL over HSPA –improved spectrum efficiency = 2~3 times in UL over HSPA Increased service provisioning – more services at lower cost with better user experience –sub-5 ms for small IP packet –Increase cell edge bit rate –From camped state to end-to-end bearer setup should less than 100 ms –From dormant state to end-to-end bearer setup should less than 50 ms Flexibility of use of existing and new frequency bands –Scalable BW = 1.4, 3, 5, 10, 15, 20 MHz) Simplified architecture, Open interfaces –Coexistence with legacy standards while evolving toward all IP network Mobility is optimized –Optimized for low mobile speed (0~15 km/h) –High performance for high mobile speed (15 ~ 120 km/h) –Mobility is maintained up to mobile speed (120 ~ 350 km) Allow for reasonable terminal power consumption

System Architecture Evolution (SAE)

Radio Bearer Services

E-UTRAN Architecture, X2 interface is NOT supported in femto (HeNB)

Functional Split between E-UTRAN and EPC,

Protocol Stack, may optionally terminate the user plane towards the HeNB - may optionally provide a relay function for relaying User Plane data between the HeNB and the S- GW. - shall terminate the non-UE- dedicated procedures – both with the HeNB, and with the MME. - shall provide a relay function for relaying Control Plane data between the HeNB and the MME. - Any protocol function associated to an UE-dedicated-procedure shall reside within the HeNB and the MME only. in 3G femto, Iuhin 3G femto, IuCS or IuPS

Application Interface, The SCTP layer provides the guaranteed delivery of application layer messages. - A single SCTP association per S1-MME interface instance shall be used with one pair of stream identifiers for S1-MME common procedures. - The S1-U interface provides non guaranteed delivery of user plane PDUs between the eNB and the S-GW. - The transport network layer is built on IP transport and GTP-U is used on top of UDP/IP to carry the user plane PDUs between the eNB and the S-GW.

Control Plane Application (S1) Functions, S1 Paging function S1 UE Context Management function Initial Context Setup Function UE Context Modification Function Mobility Functions for UEs in ECM-CONNECTED E-RAB Service Management function NAS Signalling Transport function NAS Node Selection Function S1-interface management functions MME Load balancing Function Location Reporting Function Warning Message Transmission function Overload Function RAN Information Management Function S1 CDMA2000 Tunnelling function Configuration Transfer Function LPPa Signalling Transport function Trace Function

Page 10 An EP (Elementary Procedure) consists of an initiating message and possibly a resp onse message. Two kinds of EP’s are used: -Class 1: Elementary Procedures with response (success and/or failure). -Class 2: Elementary Procedures without response. For Class 1 EP’s, the types of responses can be as follows: Successful: -A signalling message explicitly indicates that the elementary pro cedure successfully completed with the receipt of the response. Unsuccessful: -A signalling message explicitly indicates that the EP failed. -On time supervision expiry (i.e. absence of expected response). Successful and Unsuccessful: -One signalling message reports both successful and unsuccessful outcome for the different included requests. The response message used is the one defined for successful outcome. Class 2 EP’s are considered always successful. S1-AP (S1 Application Protocol) Elementary Procedure (TS ):

Page 11 S1-AP Class 1 Procedures: Elementary Procedure: Initiating Message:Successful Outcome:Unsuccessful Outcome: Response message: Handover PreparationHANDOVER REQUIREDHANDOVER COMMANDHANDOVER PREPARATION FAILURE Handover Resource Allocation HANDOVER REQUESTHANDOVER REQUEST ACKNOWLEDGE HANDOVER FAILURE Path Switch RequestPATH SWITCH REQUESTPATH SWITCH REQUEST ACKNOWLEDGE PATH SWITCH REQUEST FAILURE Handover CancellationHANDOVER CANCELHANDOVER CANCEL ACKNOWLEDGE SAE Bearer SetupSAE BEARER SETUP REQUESTSAE BEARER SETUP RESPONSE SAE Bearer ModifySAE BEARER MODIFY REQUESTSAE BEARER MODIFY RESPONSE SAE Bearer ReleaseSAE BEARER RELEASE COMMAND SAE BEARER RELEASE COMPLETE Initial Context SetupINITIAL CONTEXT SETUP REQUEST INITIAL CONTEXT SETUP RESPONSEINITIAL CONTEXT SETUP FAILURE ResetRESETRESET ACKNOWLEDGE S1 SetupS1 SETUP REQUESTS1 SETUP RESPONSES1 SETUP FAILURE UE Context ReleaseUE CONTEXT RELEASE COMMAND UE CONTEXT RELEASE COMPLETE UE Context ModificationUE CONTEXT MODIFICATION REQUEST UE CONTEXT MODIFICATION RESPONSE UE CONTEXT MODIFICATION FAILURE eNB Configuration UpdateENB CONFIGURATION UPDATEENB UPDATE CONFIGURATION ACKNOWLEDGE ENB CONFIGURATION UPDATE FAILURE MME Configuration UpdateMME CONFIGURATION UPDATEMME CONFIGURAION UPDATE ACKNOWLEDGE MME CONFIGURATION UPDATE FAILURE

Page 12 S1-AP Class 2 Procedures: Elementary ProcedureMessage Handover NotificationHANDOVER NOTIFY SAE Bearer Release RequestSAE BEARER RELEASE REQUEST PagingPAGING Initial UE MessageINITIAL UE MESSAGE Downlink NAS TransportDOWNLINK NAS TRANSPORT Uplink NAS TransportUPLINK NAS TRANSPORT NAS non delivery indicationNAS NON DELIVERY INDICATION Error IndicationERROR INDICATION UE Context Release RequestUE CONTEXT RELEASE REQUEST DownlinkS1 CDMA2000 TunnelingDOWNLINK S1 CDMA2000 TUNNELING Uplink S1 CDMA2000 TunnelingUPLINK S1 CDMA2000 TUNNELING UE Capability Info IndicationUE CAPABILITY INFO INDICATION eNB Status TransfereNB STATUS TRANSFER MME Status TransferMME STATUS TRANSFER Deactivate TraceDEACTIVATE TRACE Trace StartTRACE START Trace Failure IndicationTRACE FAILURE INDICATION Location Reporting ControlLOCATION REPORTING CONTROL Location Reporting Failure IndicationLOCATION REPORTING FAILURE INDICATION Location ReportLOCATION REPORT

Page 13 LTE HeNB Management and SON - 3GPP TS specifies the Information Model for Home eNodeB Type 1 Interface for the remote management using the TR-069 CWMP - SON (Self Organizing Network) Strategy per Load Balancing between eNBs for handover optimization Optimization of handover parameter to improve success ratio of handover Prevention of under-utilization of radio resources. Counter-balancing of inter-cell interference Optimization of network coverage Maximize the system capacity Traffic counters identify capacity problems Maintain the level of RACH collision probability so that call setup delay is satisfied. Maintain the resource for RACH so that minimize waste

Page 14 Procedure of SON, Rel 8

Downlink Channel Mapping,,

Downlink Channel Structure,, Packet to UE1 Packet to UEn

Downlink Transport Channel Types, Broadcast Channel (BCH) characterized by: fixed, pre-defined transport format requirement to be broadcast in the entire coverage area of the cell. Downlink Shared Channel (DL-SCH) characterized by: support for HARQ support for dynamic link adaptation by varying the modulation, coding and transmit power possibility to be broadcast in the entire cell possibility to use beam-forming support for both dynamic and semi-static resource allocation support for UE discontinuous reception (DRX) to enable UE power saving. Paging Channel (PCH) characterized by: support for UE discontinuous reception (DRX) to enable UE power saving (DRX cycle is indicated by the network to the UE) requirement to be broadcast in the entire coverage area of the cell mapped to physical resources which can be used dynamically also for traffic/other control channels. Multicast Channel (MCH) (from Release 9) characterized by: requirement to be broadcast in the entire coverage area of the cell support for MBSFN combining of MBMS transmission on multiple cells support for semi-static resource allocation e.g., with a time frame of a long cyclic prefix.

Downlink Physical Channel Type, Channels: Physical downlink shared channel (PDSCH) Carries the DL-SCH and PCH. DL-SCH contains actual user data. Physical downlink control channel(PDCCH) Informs the UE about the resource allocation of PCH and DL-SCH, and HARQ information related to DL-SCH. Carries the uplink scheduling grant. Physical HARQ indicator channel (PHICH) Carries ACK/NACKs in response to uplink transmissions. Physical control format indicator channel(PCFICH) Informs the UE about the number of OFDM symbols used for the PDCCHs; Transmitted in every sub-frame. Physical broadcast channel (PBCH) The coded BCH transport block is mapped to for subframes within a 40 ms interval. Signals: Reference signal Synchronization signal (P-SS and S-SS) PDCCH for mat Number of CCEs Number of resourc e-element groups Number of PD CCH bits Table : Supported PDCCH formats. in Physical channelModulation schemes PDCCHQPSK Table : PDCCH modulation schemes. in

Downlink Physical Channel Allocation, kHz Resource element allocation priorities Ref signal > P-SS > S-SS > PBCH > PDCCH > PDSCH - PBCH and PDCCH never be allocated to same resource element - P-SS is allocated to last symbol of slot #0 and #10 in central 62 sub-carrier for flexible BW allocation - S-SS is allocated to slot just before P-SS - Ref signal is allocated to every #0 and #4 slot - PBCH is allocated to first symbol of slot #1 - PDCCH can be allocated to first 3 symbols - The remaining areas can be used for the PDSCH

Uplink Channel Mapping, RACH is NOT mapped to logical channel because RRC Connection Request is sent via CCCH – UL-SCH – PUSCH.

Uplink Transport Channel Types,, Uplink Shared Channel (UL-SCH) characterized by: possibility to use beam-forming (likely no impact on specifications) support for dynamic link adaptation by varying the transmit power and potentially modulation and coding support for HARQ support for both dynamic and semi-static resource allocation. Random Access Channel(s) (RACH) characterized by: limited control information collision risk

Uplink Channel Structure, App 1 (FTP)App 2 (Voice)

Uplink Physical Channel, Channels: Physical uplink shared channel (PUSCH) Carries the UL-SCH, ACK/NACK and CQI. UL-SCH contains actual user data. Physical uplink control channel (PUCCH) Carries ACK/NACKs in response to downlink transmission. Carries CQI (Channel Quality Indicator) report and SR (Scheduling Request). Physical random access channel (PRACH) Carries random access preamble. Signals: Demodulation reference signal (UL-RS), associated with transmission of PUSCH and PUCCH. Sounding reference signal (SRS), not associated with transmission of PUSCH and PUCCH.

Uplink Physical Channel, Sounding Reference Signal (SRS) which is used to allow channel dependent (i.e. frequency selective) uplink scheduling as the DM-RS cannot be used for this purposes since they are assigned over the assigned bandwidth to a UE.

Uplink Resource Grid, Channels: Physical uplink shared channel (PUSCH) Carries the UL-SCH, ACK/NACK and CQI. UL- SCH contains actual user data. Physical uplink control channel (PUCCH) Carries ACK/NACKs in response to downlink transmission. Carries CQI (Channel Quality Indicator) report and SR (Scheduling Request). Physical random access channel (PRACH) Carries random access preamble. Signals: Demodulation reference signal (UL-RS), associated with transmission of PUSCH and PUCCH. Sounding reference signal (SRS), not associated with transmission of PUSCH and PUCCH.

Soft Frequency Reuse scheme for LTE using OFDMA to mitigate interference -How much power should be transmitted for each freq to maximize cell capacity ? => This is issue related Self Optimization in SON