Table of contents
1. 4/5G dual connection topology based on option 3/3a/3x architecture
2. 4/5G dual connection topology based on option 4/4a architecture
3. 4/5G dual connection topology based on option 7/7a/7x architecture
| Advantage | disadvantage | ||
| Independent networking SA | option 2 option 5 |
No impact on the existing 2G/3G/4G network, no impact on existing network users; It can be quickly deployed and directly introduces new 5G network elements, without the need to modify the existing network; Introduce 5GC to provide new 5G functions and services. |
When 5G NR does not have continuous coverage, voice continuity depends on cross-system switching, and QoS cannot be guaranteed; NR and 5GC need to be deployed at the same time, and the cost is high. |
| Non-independent networking NSA【MR-DC (4/5G dual connection)】 | option 3 series | Connect EPC+eNB as MN; gNB as SN; |
Unable to support new services introduced by 5GC |
| option 7 series | Data services have no requirement for NR coverage; Support new services introduced by 5GC, realize full 5G capabilities, and effectively avoid multiple upgrades of subsequent wireless networks; Voice service continuity is guaranteed by VoLTE, requiring continuous VoLTE coverage; It is suitable for introduction when the 5GC industry is mature. |
New 5GC needs to be built, and the progress of network construction depends on the maturity of the 5GC industry; It is necessary to promote the voice fallback process of CSFB from 5G to 2G/3G network; LTE needs to be transformed and upgraded to eLTE, which requires major changes. |
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| option 4 series | The 5G base station is the master station, the 4G base station is the slave station, and the master and slave stations share the 5G core network. | ||
1. 4/5G dual connection topology based on option 3/3a/3x architecture
Among them, the 4G EPC serves as the core network, the eNB serves as the MN, and the gNB serves as the SN.
Wherein, the eNB serves as the MN, the EPC transmits the key to the eNB through the S1 interface, and the split bearer is on the eNB.
Option 3 establishes an MCG Split bearer on the eNB to carry split bearers.
Option 3a establishes an SCG bearer on the gNB, and the bearer does not split.
Wherein, the eNB acts as the MN, and the EPC transmits the key to the eNB through the S1 interface .
Option 3x establishes SCG Split bearer on gNB to carry split bearer.
2. 4/5G dual connection topology based on option 4/4a architecture
Wherein, eLTE eNB is also called NG-eNB , and the interface between NG-eNB and gNB is Xn interface.
Among them, the gNB acts as the MN, and the 5GC transmits the key to the gNB through the NG port.
Option 4 establishes an MCG Split bearer on the gNB to carry split bearers.
Option 4a establishes the SCG bearer on the NG-eNB, and the bearer does not split.
3. 4/5G dual connection topology based on option 7/7a/7x architecture
Among them, 5GC serves as the core network, NG-eNB serves as the MN, and gNB serves as the SN.
Among them, the NG-eNB acts as the MN, and the 5GC transmits the key to the NG-eNB through the NG port.
Option 7 establishes an MCG Split bearer on the NG-eNB to carry split bearers.
Option 7a establishes the SCG bearer on the gNB, and the bearer does not split.
Among them, option 7x establishes the SCG bearer on the gNB, and the bearer is split.
| bearer type | describe | advantage | shortcoming | Applicable business |
| MCG bearer | The anchor point of the user plane is at the master eNB (MeNB), and only uses MeNB resources | No forward/backhaul delay; The data anchor point is in the MeNB, and the anchor point change will not be triggered frequently. |
SeNB high-frequency resources cannot be used | Services that do not require high speed but require high stability; Faster-moving business. |
| SCG bearer | The anchor point of the user plane is at SeNB, and only uses SeNB resources | No forward/backhaul delay; Higher rate and lower latency can be provided by using high-frequency resources |
When the high frequency touches the blockage/deafness of the red line, only trigger the bearer type change back to low frequency; The coverage of SeNB is limited, when the SeNB changes, the user plane anchor point change process needs to be triggered |
Services that have high requirements on speed and delay and move slowly, such as URLLC services |
| MCG split bearer | The anchor point of the user plane is at MeNB, and both MeNB and SeNB resources are used | High frequency and low frequency resources can be used at the same time; The signaling process caused by blockage/deafness can be avoided through the routing strategy of split bearer; The data anchor point is in the MeNB, and the anchor point change will not be triggered frequently. |
Pre-transmission/post-transmission delay and reordering delay will introduce additional delay | Services that require high speed but low latency; Faster-moving business |
| SCG split bearer | The anchor point of the user plane is at SeNB, and both MeNB and SeNB resources are used | High frequency and low frequency resources can be used at the same time; The signaling process caused by blockage/deafness can be avoided through the routing strategy of split bearer; |
Pre-transmission/post-transmission delay and reordering delay will introduce additional delay, but when the problem occurs only at high frequency and low frequency is backup, the problem will be weakened; The coverage of SeNB is limited, when the SeNB changes, the user plane anchor point change process needs to be triggered |
Services that have high requirements on speed, delay, and reliability and move slowly |