5G协议 接口介绍
計算機網絡
采用更好理解的方式,分為5層
應用層:直接為用戶應用進程提供服務,到運輸層到應用的信息進行處理(解密,以何種方式展示給你,比如文字消息:正楷?,行書?),然后可以展示給你。
運輸層:負責運輸網絡層的信息給應用層,主要功能包括分用和復用。
分用:就是把接收到來自網絡層分開交付給應用層相應的進程(有端口號)
復用:所有來著應用進程的數據(加頭信息,有IP???和端口,只加端口???)進行封裝,然后發送到網絡層
網絡層:為交換網上的不同主機之間提供通信服務,有IP協議,選擇合適的路由(路徑),使源主機傳下來的數據,能夠通過網絡中的路由器找到目的主機。(一種協議,更像概念上的,只是教你如何找路徑)。
數據鏈路層:兩個主機之間數據傳輸,總是在一段一段的鏈路上,相鄰兩個點之間,是點對點直接傳送的。需要專門的鏈路層協議,數據鏈路層將網絡層交下來的IP數據報組裝成幀(framing),在兩個相鄰結點間的鏈路上“透明”地傳送幀(frame)中的數據(有同步信息:有沒有完全送到,地址信息:發到哪里?差錯控制:有錯,馬上停止,重發)。
物理層(physical layer):在物理層上傳送的數據的單位是比特,物理層的任務就是透明地傳送比特流。(可以理解為物理媒介,如雙絞線、同軸電纜、光纜、無線信道等,很小很小一個個單元,1 bit 1bit的往下傳)。
主要功能:
(1)gNB:Radio Resource Management,無線資源管理;Radio Bearer Control,無線承載控制;Radio Admission Control無線接入控制; Connection Mobility Control 連接移動性控制;Measurement configuration & Provision;測量配置和規定;Dynamic Resource Allocation 動態資源分配(安排)
(2)AMF:NAS (Non-access stratum) Security非接入層安全;idle State Mobility Handling空閑狀態移動處理
(3)UPF:Mobility Anchoring移動性錨定;PDU handling協議數據單元處理
(4)SMF(Session Management function):UE IP address allocation UE IP地址分配; PDU Session Control 協議數據單元會話控制
4.3 Network Interfaces
網絡接口
1.NG interface
NG User Plane:The NG user plane interface (NG-U) is defined between the NG-RAN node and the UPF. The user plane protocol stack of the NG interface is shown on Figure 4.3.1.1-1. 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 NG-RAN node and the UPF.
NG-U,連接NG-RAN和UPF,NG接口用戶面協議棧
運輸網絡層在IP傳輸層之上,使用GPRS Tunneling Protocol-User(GPRS隧道協議:用戶,在UDP/IP之上)傳遞在NG-RAN節點和UPF的用戶面數據協議單元。
NG-U provides non-guaranteed delivery of user plane PDUs between the NG-RAN node and the UPF.
NG-U使用的UDP協議,不能保證完全準確的傳送。
NG Control Plane:
The NG control plane interface (NG-C) is defined between the NG-RAN node and the AMF. The control plane protocol stack of the NG interface is shown on Figure 4.3.1.2-1. The transport network layer is built on IP transport. For the reliable transport of signalling messages, SCTP is added on top of IP. The application layer signalling protocol is referred to as NGAP (NG Application Protocol). The SCTP layer provides guaranteed delivery of application layer messages. In the transport, IP layer point-to-point transmission is used to deliver the signalling PDUs.
NG-C在 NG-RAN節點和AMF之間,運輸網絡層在IP傳輸層之上,為了可靠的信令傳輸,SCTP添加在IP層之上,應用層信令協議被稱為NGAP,SCTP(Stream Control Transmission Protocol)保證了應用層消息的可靠的傳輸,在運輸IP層點對點傳輸被用于傳輸信令協議數據單元。
NG-C provides the following functions:
- NG interface management;
NG接口管理
- UE context management;
UE上下文管理
- UE mobility management;
UE移動性管理
- Transport of NAS messages;
NAS信息傳輸
- Paging;
尋呼
- PDU Session Management;
協議數據單元會話管理
- Configuration Transfer;
配置轉移
- Warning Message Transmission.
警告消息傳輸
與控制有關的NGAP,有AP存在,采用TCP/IP協議???
Xn interface
Xn User Plane:The Xn User plane (Xn-U) interface is defined between two NG-RAN nodes. The user plane protocol stack on the Xn interface is shown in Figure 4.3.2.1-1. 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.Xn-U(用戶面)在兩個NG-RAN節點之間,運輸網絡層在IP運輸層之上,用GTP-U協議(UDP/IP)來傳輸用戶面PDUs
Xn Control Plane:The Xn control plane interface (Xn-C) is defined between two NG-RAN nodes. The control plane protocol stack of the Xn interface is shown on Figure 4.3.2.2-1. The transport network layer is built on SCTP on top of IP. The application layer signalling protocol is referred to as XnAP (Xn Application Protocol). The SCTP layer provides the guaranteed delivery of application layer messages. In the transport IP layer point-to-point transmission is used to deliver the signalling PDUs.
Xn-C在兩個NG-RAN節點之間,應用層信令協議稱為XnAP,SCTP(Stream Control Transmission Protocol)層協議保證應用層的信息的可靠傳輸。在IP層點對點傳輸被用于傳遞信令數據
Xn-C functions:
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Xn interface management; Xn接口管理;
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UE mobility management, including context transfer and RAN paging:UE移動性管理,包括上下文傳輸和RAN尋呼:
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Dual connectivity.雙連接(4G和5G???)
4.4 Radio Protocol Architecture
無線協議架構
The figure below shows the protocol stack for the user plane, where SDAP, PDCP, RLC and MAC sublayers (terminated in gNB on the network side) perform the functions listed in subclause 6.
SDAP(Service Data Adaptation Protocol),PDCP(Packet Data Convergence Protocol), RLC(Radio Link Control)and MAC子層終結于gNB網絡側
PDCP, RLC and MAC(subclause 6),
RRC(subclause 7),radio resource control
NAS(Non-access stratum) control protocol(非接入層控制協議)
NAS control protocol (terminated in AMF on the network side) performs the functions listed in 3GPP TS 23.501 [3]), for instance: authentication, mobility management, security control…認證,移動管理和安全控制
4.5 Multi-RAT Dual Connectivity
多RAT雙連接(Radio Access Technology)
NG-RAN supports Multi-RAT Dual Connectivity (MR-DC) operation whereby a UE in RRC_CONNECTED is configured to utilise radio resources provided by two distinct schedulers, located in two different NG-RAN nodes connected via a non-ideal backhaul and providing either E-UTRA (i.e. if the node is an ng-eNB) or NR access (i.e. if the node is a gNB). Further details of MR-DC operation can be found in 3GPP TS 37.340 [21].
NG-RAN支持多接入雙連接操作,從而一個UE在RRC_CONNECTED狀態下被配置為利用兩個不同調度程序提供的無線資源,調度程序位于兩個不同的NG-RAN節點中(通過非理想的回程連接)并且提供E-UTRA或者NR接入。
總結
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