add architecture components definitions

Signed-off-by: weichen <niweichen@chinamobile.com>
Change-Id: I7462e8ef684fa55bfc5232ab156e2c12f655df26

diff --git a/docs/architecture/architecture.rst b/docs/architecture/architecture.rst
index 0243942..ddcf6ce 100644 (file)
--- a/docs/architecture/architecture.rst
+++ b/docs/architecture/architecture.rst
@@ -15,4 +15,30 @@ Figure 1: O-RAN architecture overview
 
 In the O-RAN architecture, the radio side includes Near-RT RIC, O-CU-CP, O-CU-UP, O-DU, and O-RU. The management side includes Service Management and Orchestration Framework that contains a Non-RT-RIC function. 
 
+Components Definition
+---------------------
+For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in 3GPP TR 21.905 [1].
+
+near-RT RIC: O-RAN near-real-time RAN Intelligent Controller: a logical function that enables near-real-time control and optimization of O-RAN elements and resources via fine-grained data collection and actions over E2 interface.
+
+non-RT RIC: O-RAN non-real-time RAN Intelligent Controller: a logical function that enables non-real-time control and optimization of RAN elements and resources, AI/ML workflow including model training and updates, and policy-based guidance of applications/features in near-RT RIC.
+
+NMS: A Network Management System 
+
+O-CU: O-RAN Central Unit: a logical node hosting RRC, SDAP and PDCP protocols
+
+O-CU-CP: O-RAN Central Unit – Control Plane: a logical node hosting the RRC and the control plane part of the PDCP protocol
+
+O-CU-UP: O-RAN Central Unit – User Plane: a logical node hosting the user plane part of the PDCP protocol and the SDAP protocol
+
+O-DU: O-RAN Distributed Unit: a logical node hosting RLC/MAC/High-PHY layers based on a lower layer functional split.
+
+O-RU: O-RAN Radio Unit: a logical node hosting Low-PHY layer and RF processing based on a lower layer functional split.  This is similar to 3GPP’s “TRP” or “RRH” but more specific in including the Low-PHY layer (FFT/iFFT, PRACH extraction).  
+
+O1: Interface between management entities in Service Management and Orchestration Framework and O-RAN managed elements, for operation and management, by which FCAPS management, Software management, File management shall be achieved. 
+
+O1*: Interface between Service Management and Orchestration Framework and Infrastructure Management Framework supporting O-RAN virtual network functions.
+
+xAPP: Independent software plug-in to the Near-RT RIC platform to provide functional extensibility to the RAN by third parties.
+