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This standard is one of the technical standards of LTE-based vehicular communication, of which, the composition and titles are as follows:
a) YD/T 3400-2018 General technical requirements of LTE-based vehicular communication;
b) YD/T 3340-2018 Technical requirements for air interface of LTE-based vehicular communication;
c) YD/T 3707-2020 Technical requirements of network layer of LTE-based vehicular communication;
d) YD/T 3709-2020 Technical requirements of message layer of LTE-based vehicular communication.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. The issuing body of this document shall not be held responsible for identifying any or all such patent rights.
This standard was proposed by and is under the jurisdiction of China Communications Standards Association.
Technical requirements of network layer of LTE-based vehicular communication
1 Scope
This standard specifies the technical requirements of network layer of LTE-based vehicular communication, including short message protocol, application registration, service management and service advertisement, specifically including the network layer framework, data sublayer technical requirements, management sublayer technical requirements and access point and service primitives.
This standard is applicable to network layer of LTE-based vehicular communication.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
YD/T 3340-2018 Technical requirements for air interface of LTE-based vehicular communication.
YD/T 3400-2018 General technical requirements of LTE-based vehicular communication
3 Abbreviations
For the purposes of this document, the following abbreviations apply.
AID Application ID
CBR Channel Busy Ratio
DME Dedicated Management Entity
DSA Dedicated Service Advertisement
DSM Dedicated Short Message
DSMP Dedicated Short Message Protocol
IP Internet Protocol
LTE Long Term Evolution
LTE-V2X LTE Vehicle to Everything
MAC Medium Access Control
MIB Management Information Base
PDB Packet Delay Budget
PDCP Packet Data Convergence Protocol
PPPP ProSe Per-Packet Priority
SAP Service Access Point
SDU Service Data Unit
TCP Transmission Control Protocol
UDP User Data Protocol
4 Technical requirements of network layer
4.1 System introduction
The LTE Vehicle to Everything (LTE-V2X) realizes the information interaction among different subsystems of intelligent transportation system, thus realizing different applications such as road safety, traffic efficiency and information service. Figures 1 and 2 show the relationship between communication nodes involved in this standard.
Figure 1 Communication between vehicles
Figure 2 Communication between vehicle and road side facility
4.2 Network layer framework
See Figure 3 for the network layer framework of LTE Vehicle to Everything. The network layer may support access layer transmission technology based on Uu interface and PC5 interface.
Note:
1 The network layer consists of data sublayer and management sublayer.
2 The data sublayer mainly comprises adaptation layer, IP and UDP/TCP as well as DSMP. The IP and the DSMP are optional. The data sublayer transmits both data streams between application layers and data streams between different device management layer entities or between management layer entities and applications.
3 The management sublayer mainly performs functions such as system configuration and maintenance. It transmits management data streams between different devices by using the data sublayer service. Among them, DME is a universal set of management services, which provides management interfaces for all data sublayer entities, including DSMP.
Figure 3 Framework of network layer of LTE Vehicle to Everything
4.3 Technical requirements of data sublayer
4.3.1 General
The data sublayer in the network layer of the LTE Vehicle to Everything comprises TCP/UDP, IP, DSMP and adaptation layer, wherein the IP and the UDP/TCP are not within the scope of this standard.
IP data flow and DSMP data flow are specified in the network layer of LTE Vehicle to Everything, with IP data flow as shown in Figure 4 and DSMP data flow as shown in Figure 5. See YD/T 3400-2018 for data stream transmission when Uu interface is used in access layer.
Figure 4 IP data stream
Figure 5 DSMP data stream
4.3.2 Adaptation layer
The adaptation layer provides the transmission adaptation function between the underlying access technology (LTE V2X) and the upper layer protocol stack. The adaptation layer receives the DSMP data packet, the IP data packet, or the DME data packet sent by the upper layer, distinguishes the underlying interface used by the data packet to be sent, and delivers the corresponding data packet to the bottom layer in line with the corresponding access layer interface for transmission; or receives the data packet from the bottom layer, distinguishes the upper layer protocol type to which the corresponding data packet belongs, and delivers the data packet to the specified upper layer protocol stack. For the receiving of UE, if the adaptation layer cannot distinguish the upper layer protocol type to which the data packet it receives belongs, the data packet is discarded.
The adaptation layer functions also include mapping between Application ID and Destination Layer-2 ID, generation/change/maintenance of source Layer-2 ID, mapping between unicast/multicast address and Layer-2 ID, mapping between message priority and ProSe Per-Packet Priority (PPPP), mapping of PPPP to Packet Delay Budget (PDB), service period indicating to bottom layer, Channel Busy Ratio or maximum data rate indicating to upper layer, etc. The format of the adaptation layer frame is as shown in Figure 6. The adaptation layer frame includes an adaptation layer frame header and an adaptation layer payload, and there is no adaptation layer frame header when IP data is transmitted. The adaptation layer payload is used to encapsulate the upper layer data packets. The bit sequence in the adaptation layer frame format is high bit first.
Foreword i 1 Scope 2 Normative references 3 Abbreviations 4 Technical requirements of network layer Annex A (Normative) Types and values of ProtocolType Annex B (Normative) Frame structure of extended field Annex C (Normative) MIB messages Annex D (Normative) Mapping between Priority and PPPP Annex E (Informative) Adaptation layer source address/destination address design example
基于LTE的车联网无线通信技术 网络层技术要求 1 范围 本标准规定了基于LTE的车联网无线通信技术的网络层技术要求，包括短消息协议、应用注册、业务管理以及业务公告，具体包括网络层框架、数据子层技术要求、管理子层技术要求和接入点及服务原语。 本标准适用于基于LTE的车联网无线通信技术的网络层。 2 规范性引用文件 下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅所注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。 YD/T 3340—2018 基于LTE的车联网无线通信技术空中接口技术要求 YD/T 3400—2018 基于LTE的车联网无线通信技术总体技术要求 3 缩略语 下列缩略语适用于本文件。 AID 应用标识 Application ID CBR 信道忙率 Channel Busy Ratio DME 专用管理实体 Dedicated Management Entity DSA 专用业务公告 Dedicated Service Advertisement DSM 专用短消息 Dedicated Short Message DSMP 专用短消息协议 Dedicated Short Message Protocol IP 因特网互连协议 Internet Protocol LTE 长期演进技术 Long Term Evolution LTE-V2X 基于LTE的车用无线通信技术 LTE Vehicleto Everything MAC 媒介接入控制 Medium Access Control MIB 管理信息库 Management Information Base PDB 数据包时延预算 Packet Delay Budget PDCP 分组数据汇聚协议 Packet Data Convergence Protocol PPPP 邻近业务数据包优先级 ProSe Per-Packet Priority SAP 服务接入点 Service Access Point SDU 业务数据单元 Service Data Unit TCP 传输控制协议 Transmission Control Protocol UDP 用户数据报协议 User Data Protocol 4 网络层技术要求 4.1 系统介绍 基于LTE的车联网无线通信技术实现了智能运输系统的不同子系统之间的信息交互，从而实现道路安全、通行效率、信息服务等不同的应用。图1和图2给出了本标准涉及的通信节点之间的关系。
