gNB分割为CU和DU - 图文

gNB分割为CU和DU

gNB-CU和gNB-DU之间用F1接口进行连接和通信，那么问题来了，gNB应该在哪个节点上进行切割呢？理论上可以在协议栈的任何一层进行切割，依据的是运营商或主设备场景建议的部署场景。一般的切割方案如下：

这样切割的理论基础是：

此选项将允许来自NR和E-UTRA传输点的流量聚合集中化。此外，它可以方便地

管理NR和E-UTRA传输点之间的业务负载。

实现PDCP-RLC分离的基本原理已经为LTE双连接标准化了。因此，这种分离选项应该是标准化的最直接的选择，标准化所需的增量工作应该相对较小。 38.801中定义的切割点：

RRCPDCPHigh-RLCLow-RLCHigh-MACLow-MACHigh-PHYLow-PHYRFDataOption 1Option 2Option 3Option 4Option 5Option 6Option 7Option 8RRCPDCPHigh-RLCLow-RLCHigh-MACLow-MACHigh-PHYLow-PHYRFData Option 1 (1A-like split)

- The function split in this option is similar as 1A architecture in DC. RRC is in the central unit. PDCP, RLC, MAC, physical layer and RF are in the distributed unit.

Option 2 (3C-like split)

- The function split in this option is similar as 3C architecture in DC. RRC, PDCP are in the central unit. RLC, MAC, physical layer and RF are in the distributed unit.

Option 3 (intra RLC split)

- Low RLC (partial function of RLC), MAC, physical layer and RF are in distributed unit. PDCP and high RLC (the other partial function of RLC) are in the central unit.

Option 4 (RLC-MAC split)

- MAC, physical layer and RF are in distributed unit. PDCP and RLC are in the central unit.

Option 5 (intra MAC split)

- RF, physical layer and some part the MAC layer (e.g. HARQ) are in the distributed unit. Upper layer is in the central unit.

Option 6 (MAC-PHY split)

- Physical layer and RF are in the distributed unit. Upper layers are in the central unit.

Option 7 (intra PHY split)

- Part of physical layer function and RF are in the distributed unit. Upper layers are in the central unit.

Option 8 (PHY-RF split)

- RF functionality is in the distributed unit and upper layer are in the central unit.

不同的切割方案涉及到的参数如下： Opt. 1 Opt. 2 Opt. 3-2 Opt. 3-1 Opt. 5 Opt. 6 Opt. 7-3 (only for DL) Opt. 7-2 Opt. 7-1 Opt. 8 Baseline available Traffic aggregation ARQ location No No Yes (LTE DC) No Yes Yes (CPRI) DU Lowest Resource pooling in CU RRC only Transport NW latency requirement Transport NW Peak BW requirement Multi-cell/freq. coordination UL Adv. Rx Remarks N/A No UP req. - CU May be more robust under non-ideal transport conditions in between (higher on the right) Highest RRC + RRC + L2 RRC + L2 (partial) RRC + L2 + PHY (partial) L2 + PHY NOTE 7 in between (higher on the right) baseband bits Scales with MIMO layers Tight Highest Quantized IQ Quant. (f) IQ (t) Scales with antenna ports Loose Lowest multiple schedulers (independent per DU) NOTE 7 NOTE 4 NOTE 5/6 centralized scheduler (can be common per CU) NA NOTE 7 Yes NOTE 5 NOTE 5 NOTE 5 用于UP-CP分离的RAN体系结构和接口

Centralised PDCP-U with Local RRM

Centralised PDCP with Centralised RRM in separate platforms

F1接口的流程管理