OEB537110 LTE ERAN15.1 VoLTE Service Activation and Data Configuration

 

LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Disadvantage 

IMS deployment and development involves deployment and reconstruction of a large number of NEs, leading to high costs.

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The preceding figure shows shows the network architecture architecture of the VoLTE solution. As a standard VoIP VoIP solution defined by by 3GPP and IR.92 (GSMA), VoL VoLTE TE has E2E standards guarantee. 

Interworking with with other networks as well as roaming scenario support (various VoIP applications in mobile and fixed networks)

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E2E QoS supp support: ort: PCC-b PCC-based ased Qo QoS S poli policy cy

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SRVCC/eSRVCC for inter-RAT v voice oice ca callll contin continuity uity

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4G has a shorter delay. delay. 

The call setup delay is shortened to less than 2s. The delay between two VoLTE sessions is only 0.8s.

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The user-experienced delay is less than 0.05s, which is only one fourth of that on the 3G network.

4G has a lower cost. 

Compared with 2G networks, the cost of 3G networks is greatly reduced. Likewise, the cost of 4G networks is greatly reduced compared with that of 3G networks.

4G has higher spectral efficiency. It is estimated that the radio network in the 5G era will transmit data at the same rate as that of optical fibers without any delay, and be able to connect hundreds of billions of devices. 720P (750P): 1280 x 720 (720 horizontal lines, progressive scanning) 1080P (1125P): 1920 x 1080 (1080 horizontal lines, progressive scanning). The highest standard for civil civil HD videos is 1920 x 1080P/60 Hz with a line frequency of 67.5 kHz.

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Hi-Fi call, multimedia m ultimedia call, and video communication  AT&T commented that VoLTE provides u users sers with c crystal rystal clear clear voice. In mean opinion score (MOS) evaluation, a score of 0 indicates the worst quality, and 5 indicates the best quality. The quality standard of PCM is about 4.4.

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The following are common coding schemes and their MOS values: 

G.711: 4.8;

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G.721/G.723/G.726: G.721/G.723/G. 726: 4.2;

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G.728: 4.2;

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G.729: 4.2;

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G.723.1 (5.3): 3.5;

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G.723.1 (6.3): 3.98

During MOS value evaluation in a drive test, a voice box unit is usually used to

connect the voice links of the calling and called UEs. The MOS values of the calling and called UEs are the same. To evaluate the downlink MOS value of the calling UE, enable the called UE to send a standard voic voice e waveform, which will be transmitted on the network and reach the calling UE. The test software compares the received waveform with the transmitted waveform and calculates the downlink MOS value. The process for evaluating evaluating uplink MOS is similar except that the voice waveform is sent from the calling UE to the called UE.

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QCI: QoS clas class s identifier identifier

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GBR: guaranteed bit rate

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However, IMS-based VoLTE VoLTE is not appropriate for the following scenarios: scenarios: 

Transmission delay is too severe.

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Voice services are not allowed in certain frequency bands.

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Voice services are not allowed on certain frequencies.

To prevent UEs from f rom initiating voice services in VoLTE-prohibited areas or prevent VoLTE UEs from f rom being handed over to VoLTE-prohibited areas, areas, it is recommended that the following parameters or option be set: ENodeBAlgoSwitch.EutranVoipSupportSwitch , the VoipHoControlSwitch option of ENodeBAlgoSwitch.HoAlgoSwitch , and EutranInterNFreq EutranInterNFreq..VolteHoTargetInd VolteHoTargetInd..

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Radio links have a high bit error rate and a long round-trip latency. latency. To maximize the performance of the header compression technology technology on radio links, ROHC was proposed in the industry. It can be used to compress multiple types of headers, such as RTP/UDP/IP, UDP/IP, and ESP/IP headers. In actual applications, applications, it can compress

a 40-byte RTP/UDP/IP header to 1-3 bytes for transmission, greatly improving improving the radio bandwidth efficiency.

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In radio systems, the resources on the L LTE-Uu TE-Uu interface are far more precious than the processing capability of processors. Therefore, Therefore, ROHC is suitable for radio links, even though it is more complex than other header compression schemes. It is mainly used for VoIP services.

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  Packet flow: flow : A packet flow is a series of data packets using the same compression algorithm and associated with a single context. Each DRB can carry one or more packet flows.

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  Context: Context : A context contains the information about compression and decompression

characteristics of of a packet header. Each context is identified by a unique context identifier (CID). The number of concurrently activated contexts depends on the processing capabilities capabilities of the compressor and decompresso decompressor. r. Each context consists of static and dynamic fields. Static fields, such as the source and destination IP addresses, remain unchanged unchanged within a particular packet flow. Static fields are sent only when the compressor is in the Initialization and Refresh (IR) state. Dynamic fields, such as the serial number, change based on certain rules. Dynamic fields need to be updated in real time.  

  Why can packet he heade aders rs be compressed? Information in some packet header fields is redundant. For example, many fields are

duplicate between adjacent packets in a specific packet flow, such as the source and destination IP addresses in the IP headers. Information Information is also redundant within a packet header, such as the length field and checksum field in an IP header. The purpose of ROHC is to eliminate such redundant information. 

  Profile: Profile: ROHC is an extensible framework consisting of different profiles for packet flows compliant with different protocols. Profiles define the compression modes for packet flows with different types of protocol headers. Each profile is identified by a

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration

profile ID. Profile 0x0000 indicates that packet headers are not compressed.

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If both the compressor compressor and the decompress decompressor or support ROHC, ROHC is started by default when a VoIP service bearer is set up but is not started for non-VoIP services during initial access of a UE. 

ROHC is enabled by setting CellAlgoSwitch.RohcSwitch or PdcpRohcPara.RohcSwitch to ON(On) ON(On).. You are advised to use CellAlgoSwitch.RohcSwitch,, because PdcpRohcPara.RohcSwitch will be CellAlgoSwitch.RohcSwitch removed from later versions.

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The ROHC capability of a UE includes the maximum number of concurrent activated contexts (MAX_CID (MAX_CID)) and the profiles supported by the UE. The UE informs the EPC about its ROHC capability during the initial registration. The eNodeB can acquire the profiles profiles supported by the UE from the EPC or directly from the UE. After the RRC connection is set up, the EPC sends an Initial Context Setup Request message over the S1 interface to inform the eNodeB of the UE's radio capability reported by the UE during initial registration. If the eNodeB fails to obtain obtain the UE's ROHC capabil capability ity information from the EPC, the eNodeB eNodeB sends a UE Capabili Capability ty Enquiry message over the Uu interface to query the UE's ROHC capability. capability.

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The eNodeB compares the MAX_CID in the ROHC capability iinformation nformation reported by the UE with the eNodeB-supported maximum number of concurrently active active contexts per UE, and chooses the smaller one as the

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration

maximum number of concurrent contexts supported by the UE.

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During an inter-eNodeB handover within the E-UTRAN, the s source ource eNodeB informs the target eNodeB of the ROHC capabil capability ity of the UE, and the target eNodeB recalculates the capability capability of the t he UE. After the handover, the UE and the target eNodeB operate with the new ROHC parameters parameters.. 

The UE sends a measurement report in the source cell.

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The source source eNode eNodeB B makes a han handov dover er decisi decision. on. If the eNode eNodeB B decides decides to perform the handover, it sends a Handover Request message including the UE's ROHC capability information to the target eNodeB.

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 After deciding deciding to admi admitt the hand handed-over ed-over UE, the target eNodeB eNodeB calculates the ROHC parameters, which specify the maximum number of concurrently active active contexts and the profiles supported by both the UE and the target eNodeB. Then, the target eNodeB sends a Handov Handover er Request Acknowled Acknowledge ge message carrying the new ROHC parameters to the source eNodeB.

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The source eNodeB eNodeB sends an RRC Connection Connection Reconfiguration message to instruct the UE to perform the handover. handover. The m message essage carries the new ROHC parameters sent by the target eNodeB.

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The UE attempts to access the target cell.  After the UE successfully accesses the target cell, the UE and and eNodeB begin data transmission on the user plane using the new ROHC parameters.

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The operating mode of ROHC 

In Unidirectional Mode (U-Mode), packets are sent only from the compressor to the decompressor, and a feedback channel is not mandatory. Therefore, UMode is less reliable than Bidirectional Optimistic Mode (O-Mode) and Bidirectional Reliable Mode (R-Mode), (R -Mode), but its ffeedback-ind eedback-induced uced overhead is minimum compared with the overhead in O-Mode O -Mode and R-Mode.

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In O-Mode, the decompressor decompressor can send feedback messages to the compressor to indicate decompression failures or successful context updates. O-Mode is more reliable than U-Mode and requires a smaller amount of feedback than R-Mode.

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In R-Mode, the reliability of context synchronizatio synchronization n between the compressor and the decompressor decompressor is higher than that in any other mod mode. e. However However,, because of frequent feedback, R-Mode causes the largest amount of link overhead.

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Note: If the PdcpRohcPara.Profiles parameter is adjusted during eNodeB operation, the adjustment affects only new services instead of ongoing services.

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In scenarios with limited uplink coverage, the average average gain of Huawei ROHC is 6 dB and 2 dB for f or SD and HD services, meeting the expectations.

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ROHC improves both coverage and capacity. Uplink RB resources are saved by 26% and 23% for SD and HD services on average.

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Services Serv ices such as VoLTE VoLTE use a rela relative tively ly fixed packe packett size size,, and the inte interval rvals s betwe between en these packets follow follow a given pattern. For these services, services, 3GPP has introduced introduced semipersistent scheduling (SPS). During SPS, system resources (both UL and DL) DL) need to be allocated or assigned assigned only once through the PDCCH. These time-frequency

resources can then be periodically used for these services. SPS is configured using upper-layer RRC signaling. Its interv interval al is specifie specified d at the same same time. SPS is activated by allocating resources resources through the PDCCH. The UE stores the resource allocation. allocation. These resources are used repeatedly during the subsequent scheduling scheduling periods. They are not re-allocated re-allocated through the PDCCH unless adaptive retransmissio retransmissions ns occur. 

SPS plays plays a critical critical role role in incre increasin asing g VoLTE capa capacity city.. That is becaus because e VoLTE capacity is primarily primarily subjec subjectt to the PDCCH, rather than the PDSCH and PUSCH.

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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The size of a data packet for a VoLTE service has a significant difference iin n the talk spurts and silent silent period. Therefore, the the eNodeB determines the talk spurts and silent silent period for the service by checking the size of the data packet. In uplink scheduling, the eNodeB checks the size of the decompressed decompressed data p packet acket at the PDCP layer and

determines whether the the VoLTE service is is in talk spurts spurts or silent silent period. period. The data packet consists of the voice frame, IP header, header, UDP header, and RTP header. In downlink scheduling, scheduling, the eNodeB checks the PDCP SDU size before header compression and determines determines w whether hether the VoLTE service is in talk spurts or or silent period. If there is no data transmission on the SPS resources for a number of consecuti cons ecutive ve times, times, the eNo eNodeB deB dete determine rmines s that th the e VoLTE serv service ice is in the sil silent ent period. 

SPS is recommende recommended d for VoLTE serv services ices be becaus cause e SPS maximi maximizes zes VoLTE VoLTE capa capacity city while ensuring service quality. Upon initial scheduling for data transmission, the eNodeB eNod eB sends sends a scheduling scheduling indic indicator ator throu through gh the PDCC PDCCH H to the UE. If the UE

identifies SPS, the UE stores the scheduling information and transmits and receives data using the specified specified resources at a fixed interval. In SPS, UEs can use resources periodically periodicall y once the permission is granted. This mode reduces the PDCCH resources used for scheduling scheduling indications and enables the system resources to serv serve e more UEs without affecting af fecting voice voice quality and system performance. The eNodeB instructs the UE to release the semi-persistently allocated allocated time-frequency resources also through the PDCCH. Confidential Information of Huawei. No Spreading Without W ithout Permission

 

LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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This is an example of UL SPS configuration. This message con contains tains the SPS C-RNTI, SPS interval, implicit release time, power control parameters, and TDD-specific dualinterval indicator.

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RLC segmentation lowers lowers the requirements for cell-edge throughput. throughput. It is crucia cruciall to coverage.

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This table indicates that the requirement for cell-edge through throughput put is lower when RLC segmentation is used. This function improves coverage. The larger the number of segments, the better the coverage.

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 An excessiv excessive e number of RLC segments inevitabl inevitably y affects de delay, lay, to which which VoLTE services are sensitive. In addition, the number of segments affects HARQ retransmissions. retransmission s. The larger the number of segments, the smaller the number of available HARQ retransmissions. available retransmissions. The number of RLC s segments egments is controlled controlled by the eNodeB.

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Loss of UL VoLTE packets: because VoLTE packets wait in the UE buffer so long that the packet discard timer expires

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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In LTE TDD cells, the recommended v values alues vary with uplink-downlink subframe configurations: 

12 for uplink-downli uplink-downlink nk subframe configuration 0;

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8 for uplink-downlin uplink-downlink k subframe configuration 1;

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4 for uplink-downlin uplink-downlink k subframe configuration 2;

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6 for uplink-downlin uplink-downlink k subframe configuration 3;

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4 for uplink-downlin uplink-downlink k subframe configuration 4;

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2 for uplink-downlin uplink-downlink k subframe configuration 5;

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10 for uplink-downli uplink-downlink nk subframe configuration 6;

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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TTI bundling enables a transport block (TB) to be transmitted in consecutive TTIs and makes full use of the combining gain provided by HARQ to shorten the round trip time (RTT) and enhance UL coverage.

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When the UE is located at the cell edge, RLC segmentation in collaboration collaboration with TT TTII bundling produces fewer RLC segments than RLC segmentation without without TTI bundling. This reduces PDCCH overheads. overheads.

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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The following shows an example of the message.

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The 28th bit with a value of 0 (from left to right) in the characters in the red box indicates that the UE does not support TTI bundling, and the 29th bit with a value of 0

indicates that the UE does not support semi-persistent scheduling.

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Currently, only a small number of UEs support TTI bundling, and the t he coverage gain is small. Therefore, it is recommended that TTI bundling be disabled.

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Percentage of voice service UEs = L.T L.Traffic.User.Vo raffic.User.VoIP.Avg/L.Traffi IP.Avg/L.Traffic.User.Avg c.User.Avg

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Percentage of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Tot.QCI.1 L.Traffic.UL.FarUE.PktLo ss.Tot.QCI.1/L.Traffic.UL /L.Traffic.UL.PktLoss.Tot. .PktLoss.Tot.QCI.1 QCI.1

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Loss rate of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Loss.QC L.Traffic.UL.FarUE.PktLo ss.Loss.QCI.1/L.Traff I.1/L.Traffic.UL.FarUE.PktLoss ic.UL.FarUE.PktLoss.Tot.QCI.1 .Tot.QCI.1

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The eNodeB selects a pattern for voice rate control and performs voice rate control when the corresponding corresponding triggering conditions are fulfilled. For details about how voice rate control works, works, see slides "Types of Voice Rate Control" an and d "Mechanisms of Voice Rate Control".

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Cell-level parameter: CellAlgoSwitch.UlAmrcMode

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Operator-level parameter: CellOp.UlAmrcMode

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//Enabling AMR or EVS rate control 

MOD CELLALGOSWITCH: LocalCellId=0, UlAmrcMode=ADAPTIVE_ENB_CONTROL;

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//Enabling operator-level operator-level AMR or EVS rate control (The cell-level voice rate control function must also be enabled.) 

MOD CELLOP: LocalCellId=0, TRACKINGAREAID=0, UlAmrcMode=ADAPTIVE_ENB_CONTROL;

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//Setting the parameters parameters related to load-based voice rate control 

MOD CELLRACTHD: LocalCellId=0, CceThdforVolteLoadAmrc=80, CceThdforVolteLoadAmrc=80, UlRbThdforVolteLoadAmrc=60;

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//Setting the parameters related to uplink-quality-based voice rate control 

 ADD VOICEAMRCONTROL: LocalCellId=0, VoiceAmrCtrlParaGroupId=0, VoiceAmrCtrlParaGroupId=0, HighAmrCodingMode=AMR_WB_23_85kbps, LowAmrCodingMode=AMR_WB_12_65kbps, LowAmrCodingM ode=AMR_WB_12_65kbps, PlrThdForDecreasingAmr=6, PlrThdForIncreasingAmr=2,, RsnThdForDecreasingAmr=14, PlrThdForIncreasingAmr=2 RsnThdForIncreasingAmr=5;

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Percentage of voice service service UEs = L.Traffic.User.VoIP.Avg/L.Traffic.User.Av L.Traffic.User.VoIP.Avg/L.Traffic.User.Avg g

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Percentage of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Tot.QCI.1 L.Traffic.UL.FarUE.PktLo ss.Tot.QCI.1/L.Traffic.UL /L.Traffic.UL.PktLoss.Tot. .PktLoss.Tot.QCI.1 QCI.1

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Loss rate of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Loss.QC L.Traffic.UL.FarUE.PktLo ss.Loss.QCI.1/L.Traff I.1/L.Traffic.UL.FarUE.PktLoss ic.UL.FarUE.PktLoss.Tot.QCI.1 .Tot.QCI.1

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CCE usage usage = (L.ChM (L.ChMeas. eas.CCE.Co CCE.CommUsed mmUsed + L L.ChM .ChMeas.C eas.CCE.UL CE.ULUsed Used + L.ChMeas.CCE.DLUsed)/L.ChMeas.CCE.Avail

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Uplink RB usage of GBR services services = (L.ChMeas.PRB.UL.DrbUsed.Av (L.ChMeas.PRB.UL.DrbUsed.Avg.VoIP g.VoIP + L.ChMeas.PRB.UL.DrbUsed.Avg.QCI2)/L.ChMe L.ChMeas.PRB.UL.DrbUs ed.Avg.QCI2)/L.ChMeas.PRB.UL.Avail as.PRB.UL.Avail

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Uplink Packet Loss Rate (VoIP) = L.Traffic.UL.PktLoss.Loss.QCI. L.Traffic.UL.PktLos s.Loss.QCI.1/L.Traffic 1/L.Traffic.UL.PktLoss.To .UL.PktLoss.Tot.QCI.1 t.QCI.1

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Percentage of voice service UEs = L.Traffic.User.VoIP.Avg/L.Tra L.Traffic.User.VoIP.Avg/L.Traffic.User.Av ffic.User.Avg g

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Percentage of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Tot.QCI.1 L.Traffic.UL.FarUE.PktLo ss.Tot.QCI.1/L.Traffic.UL /L.Traffic.UL.PktLoss.Tot. .PktLoss.Tot.QCI.1 QCI.1



Loss rate of uplink voice packets from the cell edge = L.Traffic.UL.FarUE.PktLoss.Loss.QC L.Traffic.UL.FarUE.PktLo ss.Loss.QCI.1/L.Traff I.1/L.Traffic.UL.FarUE.PktLoss ic.UL.FarUE.PktLoss.Tot.QCI.1 .Tot.QCI.1

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Coverage-based VoLTE experience o optimization ptimization is contro controlled lled by the CellHoParaCfg.FlashSrvccSwitch CellHoParaCfg. FlashSrvccSwitch parameter.

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Flash SRVCC is controlled by the CellHoParaCfg. CellHoParaCfg.FlashSrvccSwitch FlashSrvccSwitch parameter.

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

The signaling procedure for UEs in weak-coverage areas is as follows: 

The eNodeB receives an E-RAB SETUP REQUEST message from the IMS. IMS. The message contains a request to set up a dedicated voice bearer of QCI 1 for a UE.



 After determining determining that the UE is in a weak-coverage area, the eNodeB returns an E-RAB SETUP RESPONSE message with the cause value of Radio Resource Not Available to the IMS, declining to set up a dedicated voice bearer.



Depending on the role of the UE: 

If the UE is the caller, the IMS sends an SIP message (SIP 500/380/503) to the UE, instructing the UE to initiate a CSFB procedure.



If the UE is the callee, the IMS initiates a m mobile-terminated obile-terminated procedure procedure

in the 2G CS domain, instructing the UE to initiate a CSFB procedure.

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 According to the VoLTE traffic model, a v voice oice frame iis s sent every every 20 ms. UL data transmission relies relies on the SRs sent by UEs. If an eNodeB fails to detect SRs, the scheduling may be delayed, delayed, causing the UL packet loss rate to increase. To resolve resolve packet loss caused caused by missing SR detection, UL compensation compensation scheduli scheduling ng has been

introduced. With this function, the eNodeB eNodeB identifies voice service UEs and measures the length of time a UE is not scheduled. If the duration reaches a certain threshold, the eNodeB actively sends a UL Grant to the UE to relieve relieve packet loss in this situa situation. tion. 

This function is controlled by the UlVoipSchOptSwitch option of the



CellUlschAlgo.UlEnhencedVoipSchSw parameter. The CellUlschAlgo.UlCompenSchPeriodinSpurt and CellUlschAlgo.UlCompenSchPeriodinSilence parameters control the minimum intervals for compensation scheduling during talk spurts and silent periods, respectively.

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//Setting the parameters related to UL compensation scheduling scheduling 

MOD CELLULSCHALGO: LOCALCELLID=0, ULENHENCEDVOIPSCHSW=UlVoipSchOptSwitch1&UlVoipServStateEnhancedSw-1, ULCOMPENSCHPERIODINSPURT=INTERVAL_20, ULCOMPENSCHPERIODINSILENCE=INTERVAL_160;

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Compared with VoIP Service Delay Scheduling Scheduling introduced in eRAN8.1, VoIP and Data Delay Scheduling Scheduling introduced in eRAN11.0 further classifies SR-based scheduling. The eNodeB identifies control-plane, voice, and data SRs based on the DL SRB scheduling and bearer types, and assigns assigns emergency, hi high, gh, and low

priorities to these types of SR-based scheduling. This function relatively lifts controlplane and voice voice SR/BSR scheduling priorities and lowers lowers data SR priorities, reducin reducing g the voice packet loss rate. 

The CellUlSchAlgo.UlDelaySchStrategy parameter controls the uplink delay-based scheduling policy. If this parameter is set to VOIP_DELAYSCH VOIP_DELAYSCH,, the eNodeB eNodeB assi assigns gns sche scheduli duling ng 

priorities to voice services based on their wait time. 

If this parameter is set to VOIP_AND_DATA_DELAYSCH , the eNodeB sorts the UL scheduling priorities of the following objects in descending order: control signaling signaling > SR and BSR of VoLTE services > SR of data data services > BSR of data services. services. When there is a high load of both voice and data services, voice services are preferentially scheduled to ensure voice quality.



If this parameter is set to NO_DELAYSCH NO_DELAYSCH,, the eNodeB sorts the priorities of scheduling triggered by SR and BSR of VoLTE services. A longer wait time indicates a higher scheduling priority.

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Uplink VoLTE volume estimation for dynamic scheduling allows the eNodeB to estimate the uplink service volume so that scheduling can be performed at a time. If this function is not used, the eNodeB can obtain an accurate downlink service volume but cannot obtain an accurate uplink service volume.

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Uplink VoLTE volume estimation for dynamic scheduling makes the calculatio calculation n of uplink VoLTE data volume for dynamic scheduling more accurate, and shortens the additional delay of voice packets in case the calculated volume is less than the actual volume. This function improves voice voice quality when a cell is heavily loaded and DRX is

enabled. 

This function is controlled by the UlVoLTEDataSizeEstSwitch option of the CellUlschAlgo.UlEnhencedVoipSchSw parameter.



 As shown in the figure, th this is function saves the BSR scheduling w within ithin T1, shorteni shortening ng voice delay and improving voice quality. With this function disabled, the amount of scheduled data after T cannot afford 

the two voice packets generated within T. BSR-triggered BSR -triggered scheduling scheduling is required for the remaining data after T1. 

With this function enabled, the eNodeB learns that there are two voice packets

within T, and allocates the amount of data that can afford the two voice packets after T.

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

Smart AMR voice frame recovery rresolves esolves loss of class B bits only. only. It cannot compensate for loss of class A bits.



Class A bits are used to convey the basic basic meaning of voice, and clas class s B bits are used to deliver tones.

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

//Activating uplink delay-based dynamic scheduling 

MOD CELLULSCHALGO: LOCALCELLID=0, ULDELAYSCHSTRATEGY=VOIP_AND_DATA_DELAYSCH;



//Activating uplink VoLTE volume estimation for dynamic scheduling 

MOD CELLULSCHALGO: LOCALCELLID=0, ULENHENCEDVOIPSCHSW=UlVoLTEDataSizeEstSwitch-1;



//Activating uplink uplink VoLTE continuous scheduli scheduling ng - active scheduling scheduling of voice service UEs 

(FDD) MOD CELLULSCHALGO: LOCALCELLID=0, ULENHENCEDVOIPSCHSW=UlVoLTEContinuousSchSw1&UlVoipSchOptSwitch-1;



(TDD) MOD CELLULSCHALGO: LOCALCELLID=0, ULENHENCEDVOIPSCHSW=UlEdgeActiveSchSwitch-

1&UlVoipSchOptSwitch-1; 

//Activating uplink uplink VoLTE continuous scheduli scheduling ng - uplink service status determination 

MOD CELLULSCHALGO: LOCALCELLID=0, ULENHENCEDVOIPSCHSW=UlVoLTEContinuousSchSw1&UlVoipSchOptSwitch-1;

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

The DRX technology described described in this document document refers to DRX for RRC_CONNECTED UEs. When there is is no data, the UEs on only ly need to periodically periodically monitor the PDCCH, saving their power.

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

With increasingly rich LTE applications and the extended use of smartphones, the standby time and operating time of mobile phones have gradually g radually become a major concern of users. To reduce UE power consumption, 3GPP specifications for LTE introduced DRX. Huawei eNodeBs support the C-DRX feature defined in 3GPP

specifications. (The related Huawei Huawei feature is LBFD-002017 LBFD-002017 DRX.)

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

The following factors affect DRX state transition in RRC_CONNECTED mode: 

QoS parameters, such as QCI



Parameter configuration, configuration, such as time al alignment ignment timer and DRX parameters



MAC traffic



UL and DL scheduling



Handover 



 ANR





Specia Spec iall UE DRX state transition also affects scheduling and handovers, as shown in the figure.

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

The DRX functionality f unctionality iis s jointly controlled by the general DRX switch CellDrxPara.DrxAlgSwitch and the QCI-specific DRX switch DrxParaGroup.EnterDrxSwitch.. DrxParaGroup.EnterDrxSwitch



 After the UE receives an RRC Connection Rec Reconfiguration onfiguration message with with the DRXConfiguration IE set to setup setup,, it enters DRX.



Note: 

If a UE is not in DRX mode (for example example,, when it continuously continuously performs gapassisted measurements), measurements), the eNodeB does not instruct the UE to enter DRX. This may occur if fast ANR is enabled, UE information reporting is subscribed to on the U2020, or the UE is located at the cell edge where signal strength is low.



UEs in the TTI bundling bundling state will not enter DRX.



The traffic volume threshold for entry into DRX is specified by the following following

parameters: FDD: CellDrxPara.FddEnterDrxThd TDD: CellDrxPara.TddEnterDrxThdUl and CellDrxPara.TddEnterDrxThdDl

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

On Duration 

When DRX is used, the UE does not keep its receiver off. It periodi periodically cally turns on its receiver to monitor the PDCCH for incoming signaling. This period is called On Duration and defined by the On Duration Timer. Its length is determined by the DrxParaGroup.OnDurationTimer  parameter.



DRX cycle 

 A DRX cycle is the interval be between tween the b beginnings eginnings of tw two o On Duration instances. A DRX cycle includes an On Duration and possible sleep time, as shown in the figure.



 A DRX cycle consists consists of active active time a and nd sleep time, during which which the UE stays in the active state and sleep state, respectivel respectively. y.

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SR: scheduling request

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On Duration Timer  Function

This timer specifies the time during which the UE monitors the PDCCH.

Start

This timer starts at the first subframe subframe of a DRX cycle. Timing is based on the number of consecutive PDCCH subframes.

On Duration Duration Timing Timer  Stop

 

•

•

Expiry

The UE receive receives s a DRX Command MAC MAC CE. This timer expires.

 After this timer expir expires, es, the UE ente enters rs the sleep state, no longer monitoring the PDCCH.

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DRX Inactivity Timer 

Function

This timer specifies the time during which the UE determines whether to extend its active time because of the arrival of new data. This timer provides a reference for the UE to use a short cycle.

Start

This timer starts or restarts when the UE successfully decodes a PDCCH indicating an initial uplink grant or downlink user data for this UE.

DRX Inactivity Timer 

Timing is based on the number of consecutive PDCCH subframes.

Timing Stop

Expiry

 

• •

The UE receive receives s a DRX Command MAC MAC CE. This timer expires.

 After this timer expi expires, res, the UE uses a short short cycle if the cycle is configured, and the DRX Short Cycle Timer starts or restarts. Alternatively, Alternatively, the UE uses a long cycle if no short cycle is configured.

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HARQ RTT Timer and DRX Retransmission Timer  This timer specifies the interval between the initial DL data transmission and the first DL HARQ retransmission retransmission.. This timer Function is used to determine when to start the DRX Retransmission Timer.

HARQ

Start

RTT Timer 

This timer starts and the DRX Retransmission Timer stops in either of the following f ollowing situations:  At the beginning beginning of the subframe when semi-persi semi-persistent stent DL data transmission may take place. The UE decodes a PDCCH and knows that a HARQ process will have a DL transmission in a new subframe. •

•

Timing

Timing is based on the number of PDCCH subframes.

Stop

This timer exp expires. ires.

Expiry

 After this this timer expires, expires, ifif the UE detects that that DL data data has been been received correctly, the UE takes no further action; otherwise, the DRX Retransmission Timer starts.

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

Switching from a long DRX cycle to a short DRX cycle The UE exits the long DRX cycle and enters a short DRX cycle if either of the following occurs: 

The DRX Inactivity Timer expires. If there is data to transmit, the eNodeB starts the DRX Inactivity Timer. When the DRX Inactivity Timer expires, the short DRX cycle starts.



The UE receives the DRX command MCE.  After the UE receives the DRX command MCE, the UE enters a short DRX cycle if the eNodeB eNodeB has assigned the short DRX cyc cycle le for the UE. Otherwise Otherwise,, the UE still uses the long DRX cycle.



Switching from a short DRX cycle to a long DRX cycle 

If the UE does not receive new data during a specified period after entering a short DRX cycle, it will switch to a long DRX cycle to save power.



The period before the UE switches switches to a long DRX cycle is called the lifetime of the short DRX cycle. The lifetime is measured by the number of times the short DRX cycle repeats. The DRX Short Cycle Timer, T imer, specified by the DrxParaGroup.DrxShortCycleTimer  parameter, determines determines how long the short DRX cycle runs. After the DRX Short Cycle Timer T imer expires, the UE uses the long DRX cycle.

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

The eNodeB calculates the ratio of of the number of TTIs with DL data transmission transmission to the total number of TTIs within each measurement period. It then compares the ratio with the DRX entry and exit thresholds. If the ratio meets a threshold-related condition, the eNodeB instructs the UE to enter or exit DRX accordingly.

Parameter   Name

ID

Indicates the threshold for UEs to enter the discontinuous discontinuous reception (DRX) mode in a cell that operates in FDD mode. This threshold is used in the DRX algorithm. It is expressed expressed as a proportion of the

FDD enter DRX threshold

FDD exit DRX threshold

Data amount Statistic timer 

Mean i n g

FddEnte intervals (TTIs) (TT Is) with data transmission to the total rDrxThd transmission time intervals TTIs. If the measurement result of UE traffic is equal to or lower than this threshold, the eNodeB determines that the UE should remain in DRX mode or the UE should be triggered to enter DRX mode. Indicates the threshold for UEs to exit the discontinuous discontinuous reception (DRX) mode in a cell that operates in FDD mode. This threshold is used in the DRX algorithm. It is expressed expressed as a proportion of the FddExit transmission time intervals intervals (TTIs) (TT Is) with data transmission to the total DrxThd TTIs. If the measurement result of UE traffic is higher than this threshold, the eNodeB determines that the UE should remain in the non-DRX mode or the UE should be triggered to exit the DRX mode. Indicates the length of the UE traffic measurement pe period. riod. The traffic volume of a UE during this period is measured. Based on the ountStat measurement result, result, the DRX algorithm decides whether the UE Timer  should enter or exit DRX. DataAm

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Parameter Name

 

ID

 

Meaning

On Duration Timer 

OnDurationTimer 

Indicates the length of the On Duration Timer. T imer.  A larger timer value indic indicates ates a longe longerr time UEs stay in active time and results in a shorter delay.

DRX Inactivity Timer 

DrxInactivityTimer 

Indicates the length of the DRX Inactivity Timer.

DRX Retransmission Timer 

DrxReTxTimer 

Indicates the length of the DRX Retransmission Timer.

Long Lo ng DRX DRX Cycl Cycle e

Lo Lon ngD gDrx rxCy Cycl cle e

Indicates the length of the long DRX cycle.

Short-Cycle DRX Supported Indication

SupportShortDrx

Indicates whether short DRX cycles are enabled.

Short DRX Cycle

ShortDrxCycle

Indicates the length of the short DRX cycle.

DRX Short Cycle Timer 

Indicates the length of the DRX Short Cycle Timer. If this parameter is set to 1, the length of this timer is one short DRX cycle. If this DrxShortCycleTimer  parameter is set to 2, the length of this timer is two short DRX cycles. If this parameter is set to a large value, a UE for which short DRX cycles are enabled stays in short-cycle short-cycle DRX for f or a long time.

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



The SRVCC procedure includes: includes: 

PS handover handover be betwee tween n RANs



Session transfer at IMS

The Sv interface is introduced introduced between between the MME and the MSC MSC server that is enhanced for SRVCC. The overall SRVCC procedure is as follows: 

1. The MM MME E informs the SRVCC MSC server through the Sv interface that a VoIP service is to be handed over to the CS domain.



2. The SRVCC MSC server instructs the UTRAN or GERAN to prepare for the handover.



3. The SRVCC MSC server requests that the media media gateway (MGW) provide the new media-plane information, including including the t he IP address and port number. It then notifies the service centralization and continuity application server (SCC  AS) that the media stream is to be c changed. hanged. The SCC AS is a control point for

the IMS session transfer. 

4. The SCC AS noti notifies fies the UE of the new media-plan media-plane e information information.. The UE establishes a new VoIP media stream to the MGW and releases the original VoIP media stream.



5. The MGW may need to convert the established VoIP med media ia stream to achieve interworking between between the CS voice stream and VoIP voice stream. The conversion occurs in protocol stacks and voice coding. Confidential Information of Huawei. No Spreading Without W ithout Permission

 

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This document focuses focuses on eNodeB eNodeB functions, w which hich are the same for SRVCC and eSRVCC. Therefore, SRVCC and eSRVCC are not differentiated in subsequent slides. On live live networks, eSRVCC is used used..

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

CS+PS SRVCC can be triggered if the following requirements are met: 

SRVCC to GERAN G ERAN is enabled. This ffunction unction is controlled controlled by the GeranSrvccSwitch option of the CellHoParaCfg CellHoParaCfg..HoModeSwitch parameter.



PS handover from E-UTRAN to GERAN G ERAN is enabled. This ffunction unction is controlled controlled by the GeranPsHoSwitch option of the ENodeBAlgoSwitch ENodeBAlgoSwitch..HoModeSwitch parameter.



SRVCC and PS handover are specified as QCI-specific handove handoverr policies. SRVCC and PS handover are controlled controlled by the SRVCC and PS_HO options of the InterRatPolicyCfgGroup InterRatPolicyCfgGroup..GeranGprsEdgeHoCfg parameter, respectively. respectivel y. These handover policies can be associated with a specific QCI by setting the QciPara QciPara..InterRatPolicyCfgGroupId parameter. If services with different QCIs exist, the handover policy for the highest-priority QCI prevails. The handover policy priority for each QCI is specified by the CellQciPara..QciPriorityForHo parameter. It is recommended that the CellQciPara

handover policy priority be set to the highest priority (1) for QCI 1 and the lowest priority (9) for QCI 5. 

The GeranExternalCell GeranExternalCell..CsPsHOInd parameter, which specifies whether an external GERAN cell supports CS+PS SRVCC, is set to BOOLEAN_TRUE BOOLEAN_TRUE..



The GeranExternalCell. GeranExternalCell.DtmInd DtmInd parameter, which which specifies whether a GERAN cell supports dual transmission mode (DTM), is set to DTM_AVAILABLE.. DTM_AVAILABLE

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1. After triggering triggering an SRVCC proc procedure, edure, the eNode eNodeB B delivers the in inter-RAT ter-RAT measurement configuration configuration to the UE. 2. The UE responds responds to the eNode eNodeB B with an RRC Co Connection nnection Reconfiguration Complete message. 3. After detecting that that a neighboring cel celll meets the condition for trigger triggering ing an inter-RAT handover, the UE sends a measurement report to the eNodeB. 4. The eNodeB determines that a ha handover ndover sh should ould be performe performed d an and d sends a Handover Required message containing an SRVCC HO Indication to the MME. 5. The MME separates the voice voice bearer from non-vo non-voice ice bearers and then s sends ends a Relocation Request message to both the SRVCC MSC server and target SGSN. 6. After receiving receiving the Relocation Request message, the SRVCC MSC server identifies identifies the target MSC server based on the target cell ID contained within the message. The SRVCC MSC server communicat communicates es with the target MSC server on a handover. Then,

the target MSC server instructs the target radio network controller (RNC) or base station controller (BSC) to prepare for the handover. Once the resources are ready, the target RNC or BSC responds to the target MSC server. Meanwhile, Meanwhile, the target SGSN prepares for a handover of PS services, which is the same as an inter-RAT PS handover procedure. procedure. The UE media plane is then transferred on the IMS.

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

 Add neighbor relationships relationships with GERAN: 

 ADD GERANNFREQGROUP



 ADD GERANNFREQGROUPARFCN



 ADD GERANEXTERNAL GERANEXTERNALCELL CELL



 ADD GERANNCELL

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InterRAT policy config config group ID: Indicates the group ID of co common mmon parameters parameters related to inter-RAT handovers handovers..

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E v en t

Th r es h o l d

Ac t i o n

 A1

The signal quality of the serving cell is higher than a threshold.

The eNodeB stops inter-frequency inter-frequency or inter-RAT measurements. However, in frequency-priorityfrequency-prioritybased handovers, event A1 is used to start inter-frequency measurements.

 A2

The signal quality of the serving cell is lower than a threshold.

The eNodeB starts iinter-frequency nter-frequency or inter-RAT measurements. However, in frequency-priorityfrequency-prioritybased handovers, event A2 is used to stop inter-frequency measurements.

 A3

The quality signal of an intra- The source or inter-frequency source eN eNodeB odeB initi initiates ates an intraintra- or int intererneighboring cell is higher frequency handover request. than that of the serving cell.

 A4

The signal quality of an interThe source eNodeB initiates an inter-frequency frequency neighboring neighboring cell is handover request. higher than a threshold.

 A5

 A2 + A4

B1

The signal quality of an interThe source eNodeB initiates an inter-RAT inter-RAT RAT neighboring cell is handover request. higher than a threshold.

B2

 A2 + B1

The source eNodeB initiates an inter-frequency handover request.

The source eNodeB initiates an inter-RAT inter-RAT handover request.

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

Confidential Information of Huawei. No Spreading Without W ithout Permission

 

LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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Discard timer: This parameter specifies the PDCP discard timer.

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

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LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration



 Answer to question question 1: Vo Voice ice over LTE (Vo (VoLTE) LTE) is an IMS-bas IMS-based ed voice solu solution tion defined by 3GPP.

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 Answer to question 2: Yes.

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 Answer to question question 3: VoLTE capacity e enhancement, nhancement, VoLTE coverage improvement, VoLTE quality improvement, improvement, VoLTE power sav saving, ing, and VoLTE mobility management enhancement

Confidential Information of Huawei. No Spreading Without W ithout Permission

 

LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

Confidential Information of Huawei. No Spreading Without W ithout Permission

 

LTE eRAN15.1 VoLTE Service Activation and Data Configuration Conf iguration

Confidential Information of Huawei. No Spreading Without W ithout Permission