CN103209447A - Subscriber access terminal selecting device and method supporting multi-hopping wireless local area network (WLAN) in internet of vehicles - Google Patents

Abstract

The invention relates to the internet of vehicle access selection technology in the field of intelligent transportation, and discloses a subscriber access terminal selecting device and method supporting multi-hopping wireless local area network (WLAN) in the internet of vehicles. The method includes: collecting the surrounding available access point (AP) and relay station (RS) state information, enabling an information analyzing and processing module to analyze and process service requirements and various types of information, and performing comprehensive evaluation on the service characteristics of new subscribers and state information of the waiting AP and RS so as to achieve switching control. The subscriber access terminal selecting device supports selection on mobile subscriber access modes and optimum AP/RS under the hybrid communication scene of the network of vehicles, achieves load balancing among the APs by means of access selection and switching control and improves the comprehensive performance and subscriber satisfaction degree on quality of service (OoS).

Description

Translated fromChinese

一种车联网中支持多跳WLAN的用户接入终端选择装置及方法Device and method for user access terminal selection supporting multi-hop WLAN in Internet of Vehicles

技术领域technical field

本发明涉及通信领域接入选择技术，尤其涉及车联网中移动用户接入选择终端技术。The invention relates to an access selection technology in the communication field, in particular to a mobile user access selection terminal technology in the Internet of Vehicles.

背景技术Background technique

目前，智能交通（Intelligent Transport System,ITS）领域的研究及应用已引起广泛关注，而以汽车为节点，以网络为基础，人、车、路、网协调发展的车联网作为ITS的重要组成部分，将为众多用户应用提供有效的技术支撑及实现基础。车联网应用中，全球定位系统（GPS）、传感技术及各类网络接入技术如蜂窝网络、WLAN、Ad hoc技术等有机结合，为运动中的车辆提供一种有效的网络接入，实现车辆与车辆之间及车辆与外部网络之间的通信，进而为车辆的计费管理、安全行驶、数据通信等提供解决方案。但车联网的典型应用特性，如节点高速移动导致的网络拓扑变化频繁，节点时空上分布差异导致的稀疏网络与密集网络问题，多种接入技术融合以及用户各类应用的不同QoS需求等，对网络控制技术，特别是用户的接入管理及无线资源分配等均带来巨大挑战。车联网中存在三种典型通信方式，即车辆间通信V2V（Vehicle to Vehiclecommunication）、车辆与路旁基础设施之间的通信V2I（Vehicle to Infrastructurecommunication）以及混合车辆通信HVC（Hybrid-Vehicle Communication）。At present, the research and application in the field of intelligent transportation (Intelligent Transport System, ITS) has attracted widespread attention, and the Internet of Vehicles, which uses automobiles as nodes and is based on the network, is an important part of ITS. , will provide effective technical support and implementation basis for many user applications. In the application of the Internet of Vehicles, the global positioning system (GPS), sensing technology and various network access technologies such as cellular network, WLAN, Ad hoc technology, etc. are organically combined to provide an effective network access for moving vehicles and realize Communication between vehicles and between vehicles and external networks, and then provide solutions for vehicle billing management, safe driving, data communication, etc. However, the typical application characteristics of the Internet of Vehicles, such as frequent network topology changes caused by high-speed movement of nodes, sparse network and dense network problems caused by differences in the distribution of nodes in space and time, integration of multiple access technologies, and different QoS requirements for various applications of users, etc., It brings great challenges to network control technology, especially user access management and wireless resource allocation. There are three typical communication methods in the Internet of Vehicles, namely, V2V (Vehicle to Vehicle communication) between vehicles, V2I (Vehicle to Infrastructure communication) between vehicles and roadside infrastructure, and HVC (Hybrid-Vehicle Communication).

图1给出了车联网中的主要通信方式。在车联网混合通信模式下，移动用户MN（Mobile Node）将根据自身业务需求、周围网络状态，选择优化接入方式实现网络接入。目前，无线局域网络WLAN（Wireless Local Access Network）技术，因其部署相对容易，可提供高质量业务传输，已成为VANET中重要接入方式。近年来，针对WLAN的研究多以基于AP的集中式通信模式为主，较少讨论多AP重叠覆盖，以及融合多跳模式的WLAN通信方式。文献[S.J.Zhao,K.H.Teo,Z.F.Tao,Macro Diversity Handoverand Fast Access Station Switching inWireless Multi-User Multi-Hop Relay Networks,Proc.ICC2006]公开号：[US2008/0165736A1]提出融合多跳中继的WLAN通信场景，但主要针对AP之间以及AP与RS之间的切换流程进行了详细描述，未涉及多AP、多RS应用场景下AP、RS的优化选择。文献[Y.B.B,L.Cai,X.M.Shen and H.Zhao,A cross layerbroadcast protocol for multihop emergency message dissemination in inter-vehiclecommunication,Proc.ICC2010]提出一种支持车联网多跳中继通信的分布式中继节点选择方法，以支持广播数据分发，但该方法采用中继竞争机制实现目标中继选择，将导致较长接入时延及较大信令开销。Figure 1 shows the main communication methods in the Internet of Vehicles. In the hybrid communication mode of the Internet of Vehicles, the mobile user MN (Mobile Node) will select an optimized access method to achieve network access according to its own business needs and the surrounding network status. At present, WLAN (Wireless Local Access Network) technology has become an important access method in VANET because it is relatively easy to deploy and can provide high-quality service transmission. In recent years, most of the research on WLAN has focused on the AP-based centralized communication mode, and less discussion has been made on the overlapping coverage of multiple APs and the WLAN communication mode integrating multi-hop mode. Document [S.J.Zhao, K.H.Teo, Z.F.Tao, Macro Diversity Handover and Fast Access Station Switching in Wireless Multi-User Multi-Hop Relay Networks, Proc.ICC2006] public number: [US2008/0165736A1] proposes a WLAN communication scenario integrating multi-hop relay , but it mainly describes the handover process between APs and between APs and RSs in detail, and does not involve the optimal selection of APs and RSs in multi-AP and multi-RS application scenarios. Literature [Y.B.B, L.Cai, X.M.Shen and H.Zhao, A cross layer broadcast protocol for multihop emergency message dissemination in inter-vehicle communication, Proc.ICC2010] proposes a distributed relay node that supports multi-hop relay communication in the Internet of Vehicles selection method to support broadcast data distribution, but this method uses a relay competition mechanism to achieve target relay selection, which will result in longer access delay and larger signaling overhead.

发明内容Contents of the invention

本发明针对车联网混合通信场景中融合多跳WLAN技术支持移动用户自适应选择接入模式及最佳AP/RS的应用需求而提出，提供一种基于移动终端的业务特性、路旁接入点AP及中继节点RS(Relay Station)的状态信息的接入选择装置及实现方法，支持移动用户终端对路旁AP及RS的状态信息进行实时收集及分析处理，根据用户的业务特性、AP及RS的状态信息，实现接入模式以及最佳AP/RS的选择，有效提升网络综合性能、提高用户QoS满意度。The present invention proposes to meet the application requirements of the fusion of multi-hop WLAN technology to support the mobile user's self-adaptive selection of the access mode and the best AP/RS in the mixed communication scene of the Internet of Vehicles, and provides a service characteristic based on the mobile terminal and a roadside access point. The access selection device and implementation method of status information of AP and relay node RS (Relay Station), which supports mobile user terminals to collect, analyze and process the status information of roadside AP and RS in real time, according to the user's business characteristics, AP and The status information of the RS realizes the selection of the access mode and the best AP/RS, effectively improves the comprehensive performance of the network, and improves the user's QoS satisfaction.

本发明提供一种车联网中支持多跳WLAN的移动用户接入选择终端的装置及实现方法，应用于车联网混合通信场景及多跳WLAN中，该装置包括：The present invention provides a device and implementation method for a mobile user supporting multi-hop WLAN to access a selection terminal in the Internet of Vehicles, which is applied to a mixed communication scene of the Internet of Vehicles and a multi-hop WLAN. The device includes:

监测模块：监测MN所关联接入点AP周期性广播的Beacon消息，监测用户所关联中继节点RS周期性广播的RelayAdv消息，并传送至信息收集模块；Monitoring module: monitor the Beacon message periodically broadcast by the access point AP associated with the MN, monitor the RelayAdv message periodically broadcast by the relay node RS associated with the user, and send it to the information collection module;

信息收集模块：根据Beacon消息进行AP信息的收集，根据RelayAdv消息进行RS信息的收集；Information collection module: collect AP information according to Beacon messages, and collect RS information according to RelayAdv messages;

业务感知模块：感知用户业务QoS需求；Service perception module: perceive user service QoS requirements;

信息分析处理模块：根据信息收集模块及业务感知模块的数据，确定候选AP/RS集，并传送至切换控制模块及接入选择模块；Information analysis and processing module: according to the data of the information collection module and the service perception module, determine the candidate AP/RS set, and send it to the handover control module and the access selection module;

接入选择模块：根据信息分析处理模块的信息，对用户的业务特性、候选AP及RS的状态信息进行评估，选择接入模式及最佳AP/RS；Access selection module: according to the information of the information analysis and processing module, evaluate the service characteristics of the user, the status information of candidate APs and RSs, and select the access mode and the best AP/RS;

切换控制模块：根据信息分析处理模块输出AP信息，对接入网络用户当前的各候选AP的性能进行评估，若满足切换条件，则执行切换；Handover control module: output AP information according to the information analysis and processing module, evaluate the performance of each candidate AP currently accessed by the network user, and execute the handover if the handover condition is met;

接入模块：根据接入选择模块确定的最佳目标AP，执行AP接入，根据确定的最佳目标RS，执行基于RRTS/CRTS的RS接入；Access module: perform AP access according to the best target AP determined by the access selection module, and perform RS access based on RRTS/CRTS according to the determined best target RS;

切换执行模块：根据切换控制模块确定的切换目标AP，执行AP间的切换。信息分析处理模块确定候选AP/RS集包括：根据用户邻近AP的状态信息判断该AP是否满足用户业务需求，若满足

，则该AP为候选AP；根据用户邻近RS及其所关联AP的状态信息，确定两跳链路可用带宽

，连接延时

，误包率PER_link=max(PER^RS,PER^AP)，判断该链路是否满足用户业务特性，若B_link≥B_req，D_link≤D_req，PER_link≤PER_req，则该RS为候选RS。Handover execution module: execute handover between APs according to the handover target AP determined by the handover control module. The information analysis and processing module determines the candidate AP/RS set including: judging whether the AP satisfies the service requirements of the user according to the status information of the user's neighboring APs, and if it meets the

, then the AP is a candidate AP; according to the status information of the user's neighboring RS and its associated AP, determine the available bandwidth of the two-hop link

, connection delay

, packet error rate PER_link =max(PER^RS ,PER^AP ), judge whether the link meets the user service characteristics, if B_link ≥ B_req , D_link ≤ D_req , PER_link ≤ PER_req , then the RS is a candidate RS.

接入模块接入选择具体为：如候选AP集中AP数目若M^AP>1，则根据各AP的RSS及负载状况，选择接入AP；若M^AP=1，且该AP负载低于门限值，则接入该AP；若M^AP=0，则判断候选RS集中是否存在满足业务需求的RS，记候选RS集中RS数目为N^RS，若N^RS>1，则基于RS优化选择方法选择最优接入RS；若N^RS=1，且RS的负载及该RS当前关联AP负载低于负载门限值，则接入该RS；若N^RS=0，则此次通信请求失败。Access module access selection is specifically: if the number of APs in the candidate AP set is M^AP > 1, then select the access AP according to the RSS and load status of each AP; if M^AP = 1, and the AP load is lower than the threshold value, then access the AP; if M^AP = 0, judge whether there is an RS in the candidate RS set that meets the service requirements, record the number of RSs in the candidate RS set as N^RS , if N^RS >1, select based on the RS optimal selection method Optimal access to the RS; if N^RS =1, and the load of the RS and the load of the AP currently associated with the RS is lower than the load threshold, the RS is accessed; if N^RS =0, the communication request fails.

对于M^AP>1，根据Q^AP_m=α₁RSS_m+α₂(1-L_m)，评估各候选AP性能，选择最大Q^AP_m对应的AP作为目标接入AP，其中，L_m为第m个AP的负载值，RSS_m为用户接收到来自第m个AP的RSS，α₁、α₂为标识RSS及负载状况在AP性能评估中的权重。For M^AP > 1, according to Q^AP_m = α₁ RSS_m + α₂ (1-L_m ), evaluate the performance of each candidate AP, and select the AP corresponding to the largest Q^AP_m as the target access AP, where L_m is The load value of the mth AP, RSS_m is the RSS received by the user from the mth AP, α₁ and α₂ are the weights of the RSS and load status in AP performance evaluation.

基于RS优化选择方法选择最优接入RS具体包括：若N^RS>1，则根据各RS的位置、运动速度及其关联AP的负载状况，选择接入RS，调用${Q^{\mathrm{RS}}}_n={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{2v_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_n^{\mathrm{lijk}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_n^{\mathrm{link}},$评估各候选RS性能，选择最小Q^RS_n对应的RS作为目标接入RS，其中，用户与第n个RS之间链路PER为

，第n个RS与其关联AP之间链路PER为，则用户经第n个RS与AP相连的链路PER为：

，第n个RS及其关联AP的链路负载值分别为

及

，用户经第n个RS与AP相连的链路负载值为

，△d、△v分别为发起接入用户与RS间的距离与相对速度，R_r为传输范围，P_max为最大可容忍误包率，v_max为车辆最大速度，β₁，β₂，β₃，β₄为标识RS与用户间的距离、速度、误包率及负载状况的权重。Selecting the optimal access RS based on the RS optimization selection method specifically includes: if N^RS > 1, then select the access RS according to the position, movement speed of each RS and the load status of the associated AP, and call${Q^{\mathrm{RS}}}_{\mathrm{no}}={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{2v_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_{\mathrm{no}}^{\mathrm{lijk}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_{\mathrm{no}}^{\mathrm{link}},$ Evaluate the performance of each candidate RS, and select the RS corresponding to the smallest Q^RS_n as the target access RS, where the link PER between the user and the nth RS is

, the link PER between the nth RS and its associated AP is , then the PER of the link connecting the user to the AP via the nth RS is:

, the link load values of the nth RS and its associated AP are respectively

and

, the link load of the user connected to the AP via the nth RS is

, △d, △v are the distance and relative speed between the initiating access user and RS, R_r is the transmission range, P_max is the maximum tolerable packet error rate, v_max is the maximum speed of the vehicle, β₁ , β₂ , β₃ and β₄ are the weights that identify the distance, speed, packet error rate and load status between the RS and the user.

根据切换控制模块确定切换目标AP具体包括：已接入AP的用户周期性评估候选AP集中的RSS及负载状况，若确定邻近AP的RSS及负载性能更优，则启动基于切换的负载均衡机制，执行切换至目标AP。Determining the switching target AP according to the switching control module specifically includes: the user who has accessed the AP periodically evaluates the RSS and load status of the candidate AP set, and if the RSS and load performance of the adjacent AP are determined to be better, then start the load balancing mechanism based on switching, Perform handover to the target AP.

本发明还提出一种车联网中支持多跳WLAN的移动用户MN接入终端选择方法，其特征在于，包括：监测模块监测MN所关联接入点AP周期性广播的Beacon消息，监测用户所关联中继节点RS周期性广播的RelayAdv消息，并传送至信息收集模块；信息收集模块根据Beacon消息进行AP信息的收集，根据RelayAdv消息进行RS信息的收集；业务感知模块感知用户业务QoS需求；信息分析处理模块根据信息收集模块及业务感知模块的数据，确定候选AP/RS集，并传送至切换控制模块及接入选择模块；接入选择模块根据信息分析处理模块的信息，对用户的业务特性、候选AP及RS的状态信息进行评估，选择接入模式及最佳AP/RS；切换控制模块根据信息分析处理模块输出AP信息，对接入网络用户当前的各候选AP的性能进行评估，若满足切换条件，则执行切换；接入模块根据接入选择模块确定的最佳目标AP，执行AP接入，根据确定的最佳目标RS，执行基于RRTS/CRTS的RS接入；切换执行模块根据切换控制模块确定的切换目标AP，执行AP间的切换。The present invention also proposes a method for selecting a mobile user MN access terminal supporting multi-hop WLAN in the Internet of Vehicles, which is characterized in that it includes: the monitoring module monitors the Beacon message broadcast periodically by the access point AP associated with the MN, and monitors the Beacon message associated with the user The relay node RS periodically broadcasts the RelayAdv message and sends it to the information collection module; the information collection module collects AP information according to the Beacon message, and collects RS information according to the RelayAdv message; the service perception module perceives the user's service QoS requirements; information analysis The processing module determines the candidate AP/RS set according to the data of the information collection module and the service perception module, and sends it to the handover control module and the access selection module; the access selection module analyzes the user's service characteristics, Evaluate the status information of candidate APs and RSs, select the access mode and the best AP/RS; the handover control module outputs AP information according to the information analysis and processing module, and evaluates the performance of each candidate AP currently accessed by the network user. handover condition, then perform handover; the access module performs AP access according to the best target AP determined by the access selection module, and performs RS access based on RRTS/CRTS according to the determined best target RS; the handover execution module according to the handover The handover target AP determined by the control module executes handover between APs.

本发明支持在车联网混合通信场景下移动用户接入模式以及最佳AP/RS的选择，并通过接入选择以及切换控制实现各AP间的负载均衡，可实现基于用户的优化AP/RS选择，以及基于多跳RS的WLAN数据交互，可有效减少连接延时，实现用户高效接入，降低接入延时和信令开销，提高网络的综合性能及用户QoS满意度。The present invention supports the selection of the mobile user access mode and the best AP/RS in the hybrid communication scenario of the Internet of Vehicles, and realizes load balancing among APs through access selection and switching control, and can realize user-based optimized AP/RS selection , and WLAN data interaction based on multi-hop RS, which can effectively reduce connection delay, realize efficient user access, reduce access delay and signaling overhead, and improve overall network performance and user QoS satisfaction.

附图说明Description of drawings

图1车联网主要通信方式图；Figure 1 Diagram of the main communication modes of the Internet of Vehicles;

图中的标记：AR：接入路由器，AP：接入点，BS：基站，V2V：车队车,V2I：车对基础设施,MR：移动路由器。Marks in the figure: AR: access router, AP: access point, BS: base station, V2V: fleet vehicle, V2I: vehicle-to-infrastructure, MR: mobile router.

图2本发明中Beacon消息格式；Beacon message format among Fig. 2 present invention;

图3本发明RelayAdv消息格式；Fig. 3 RelayAdv message format of the present invention;

图4本发明实现车联网中支持多跳WLAN的移动用户接入选择终端装置及平台架构图；Fig. 4 The present invention realizes the mobile user access selection terminal device and platform architecture diagram supporting multi-hop WLAN in the Internet of Vehicles;

图5本发明接入选择方法流程图；Fig. 5 is a flow chart of the access selection method of the present invention;

图6本发明切换控制方法流程图。Fig. 6 is a flow chart of the handover control method of the present invention.

具体实施方式Detailed ways

阅读和理解下面参考附图及对本发明的实施例所做的详细描述，将使本发明的目的、解决的问题及其特征通俗易懂。为使本发明的目的、技术方案和优点表达得更加清楚明白，下面结合附图及具体实施例，对本发明作进一步详细说明。图1示例性地描述了车联网中三类主要通信方式：V2V通信、V2I通信及HV通信。V2V通信是指车辆之间进行的直接或多跳通信，该通信方式不依赖于路旁的基础设施（例如，蜂窝网的BS及WLAN的AP等），如图1中车B与车C，车D与车E间的通信。V2I通信是指车辆与路旁基础设施之间的通信，如图1中车A与AP1的通信。HV通信则是V2I通信方式的延伸。当某车辆不在基础设施的覆盖范围内，或终端设备不支持与基础设施的直接连接时，该车辆可通过其他车辆的中继转发实现与外部基础设施之间的通信，如图1中，车B经过中间车辆C的转发与AP2进行的通信。图1中，AR为接入路由器，MR为移动路由器，AP为路旁接入点，BS为基站，V2V表示车与车间通信，V2I表示车与基础设施间通信，HV表示混合通信。Reading and understanding the following detailed description of the embodiments of the present invention with reference to the accompanying drawings will make the purpose of the present invention, the problem to be solved and its features easy to understand. In order to express the object, technical solution and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Figure 1 exemplarily describes three main communication modes in the Internet of Vehicles: V2V communication, V2I communication and HV communication. V2V communication refers to direct or multi-hop communication between vehicles. This communication method does not depend on roadside infrastructure (for example, BS of cellular network and AP of WLAN, etc.), as shown in Figure 1. Car B and car C, Communication between car D and car E. V2I communication refers to the communication between vehicles and roadside infrastructure, such as the communication between vehicle A and AP1 in Figure 1. HV communication is an extension of V2I communication. When a vehicle is not within the coverage of the infrastructure, or the terminal equipment does not support direct connection with the infrastructure, the vehicle can communicate with the external infrastructure through the relay and forwarding of other vehicles, as shown in Figure 1, the vehicle The communication between B and AP2 is forwarded by intermediate vehicle C. In Figure 1, AR is an access router, MR is a mobile router, AP is a roadside access point, and BS is a base station. V2V means vehicle-to-vehicle communication, V2I means vehicle-to-infrastructure communication, and HV means hybrid communication.

图2为本发明中Beacon消息格式，该消息中包含AP的唯一标识AP_ID、Beacon消息的序列号seq、Beacon消息的持续时间TTL、AP当前所用信道Channel、AP总带宽

、AP当前可用带宽

、连接延时

。Fig. 2 is the Beacon message format among the present invention, and the sequence number seq of sequence number seq, Beacon message, AP current used channel Channel, AP total bandwidth of the unique identifier AP_ID that comprises AP, Beacon message in this message

, AP current available bandwidth

, connection delay

.

图3为本发明RelayAdv消息格式，该消息中包括RS的标识R_ID、RS的运动方向R_dir、RS的运动速度R_v、RS的位置（R_x，R_y）、RS总带宽

、RS可用带宽

、RS关联AP的接收信号强度RSS_{RS_AP}、RS关联AP的总带宽

、可用带宽。Fig. 3 is the format of the RelayAdv message of the present invention, the message includes the identification R_ID of the RS, the moving direction R_dir of the RS, the moving speed R_v of the RS, the position (R_x, R_y) of the RS, and the total bandwidth of the RS

, RS available bandwidth

, RS-associated AP received signal strength RSS_{RS_AP} , RS-associated AP's total bandwidth

, available bandwidth .

图4所示为本发明装置及平台架构图，该装置由信息感知平面的网络信息收集模块、中继信息收集模块、业务感知模块及信息分析处理模块；接入优化平面的切换控制模块、接入选择模块；交互平面的网络信息监测模块、中继信息监测模块、AP接入模块、中继接入模块及切换执行模块组成。包括以下具体功能模块实体：Fig. 4 shows the device and platform architecture diagram of the present invention, the device is composed of network information collection module, relay information collection module, service perception module and information analysis and processing module of information perception plane; switching control module of access optimization plane, connection The input selection module; the network information monitoring module, the relay information monitoring module, the AP access module, the relay access module and the handover execution module of the interaction plane. Including the following specific functional module entities:

1．网络监测模块：监测MN所关联AP周期性广播的Beacon消息，并传送至网络信息收集模块。其中Beacon消息格式如图2。1. Network monitoring module: monitor the Beacon message periodically broadcast by the AP associated with the MN, and send it to the network information collection module. The Beacon message format is shown in Figure 2.

2．中继监测模块：监测用户所关联RS周期性广播的RelayAdv消息，并传送至中继信息收集模块。其中RelayAdv消息格式如图3。2. Relay monitoring module: monitor the RelayAdv message periodically broadcast by the RS associated with the user, and send it to the relay information collection module. The format of the RelayAdv message is shown in Figure 3.

3．网络信息收集模块：该模块主要实现对不同AP的相关信息的收集，更新及初步处理，可以获知MN关联AP的标识，各AP总带宽

，当前可用带宽

，连接延时、用户接收信息强度RSS_AP等信息，从而为信息分析处理模块提供预处理信息，同时也为接入选择模块接入模式及最佳AP选择提供网络侧的参量信息。3. Network information collection module: This module mainly realizes the collection, update and preliminary processing of relevant information of different APs, and can know the identification of the associated AP of the MN, the total bandwidth of each AP

, the current available bandwidth

, connection delay, user received information strength RSS_AP and other information, so as to provide preprocessing information for the information analysis and processing module, and also provide network-side parameter information for the access selection module access mode and the best AP selection.

4．中继信息收集模块：该模块实现对不同RS的相关信息的收集，更新及初步处理，该模块可以获知各RS总带宽

、可用带宽

、所在位置、移动速度v，用户接收信息强度RSS_AP，中继关联AP的可用带宽、总带宽等信息，从而为信息分析处理模块提供预处理信息，同时也为接入选择模块接入模式及最佳RS选择提供RS的参量信息。4. Relay information collection module: This module realizes the collection, update and preliminary processing of relevant information of different RSs, and this module can know the total bandwidth of each RS

, available bandwidth

, location, moving speed v, user received information intensity RSS_AP , available bandwidth of relay-associated AP , total bandwidth and other information, so as to provide pre-processing information for the information analysis and processing module, and also provide RS parameter information for the access mode and optimal RS selection of the access selection module.

5．业务感知模块：该模块主要实现对用户业务特性的感知，包括误包率PER_req、带宽需求B_req，连接时延D_req等，并输入信息分析处理模块，为候选AP及RS的选择提供参量信息。5. Service perception module: This module mainly realizes the perception of user service characteristics, including packet error rate PER_req , bandwidth requirement B_req , connection delay D_req, etc., and inputs the information analysis and processing module to provide parameters for the selection of candidate APs and RSs information.

6．信息分析处理模块：该模块主要实现对用户状态的判定以及对业务感知模块以及信息收集模块各类信息进行分析处理，确定出候选AP集及候选RS集，并将结果传送至接入优化平面的切换控制模块及接入选择模块。信息初步处理包括：6. Information analysis and processing module: This module mainly realizes the judgment of the user status and analyzes and processes various information of the service perception module and the information collection module, determines the candidate AP set and the candidate RS set, and transmits the results to the access optimization plane Switch control module and access selection module. The initial processing of information includes:

1）用户状态的判定：判断用户当前是否已接入网络，若已接入网络，触发切换控制模块，否则，触发接入选择模块；1) Judgment of user status: judge whether the user is currently connected to the network, if connected to the network, trigger the switching control module, otherwise, trigger the access selection module;

2）候选AP集确定方法：根据业务感知模块中用户的业务特性及AP信息收集模块中AP的状态信息，判断AP是否满足用户所需误包率PER_req、带宽B_req、连接时延D_req等业务需求，若满足，则该AP为候选AP。根据用户邻近AP的状态信息判断该AP是否满足用户业务需求，若满足

PER^AP≤PER_req，则该AP为候选AP；2) Method for determining the candidate AP set: According to the service characteristics of the user in the service perception module and the status information of the AP in the AP information collection module, determine whether the AP meets the user's required packet error rate PER_req , bandwidth B_req , and connection delay D_req If the service requirements are met, the AP is a candidate AP. According to the status information of the user's neighboring APs, it is judged whether the AP meets the user's service requirements.

PER^AP ≤ PER_req , then the AP is a candidate AP;

3）候选RS集确定方法：根据业务感知模块中用户的业务特性及中继信息收集模块中RS关联AP的状态信息，判断RS所关联的AP是否满足用户的业务特性，若满足，则该RS为候选RS。根据用户邻近RS及其所关联AP的状态信息，确定两跳链路可用带宽，连接延时

误包率PER_link=max(PER^RS,PER^AP)，判断该链路是否满足用户业务特性，若B_link≥B_req，D_link≤D_req，PER_link≤PER_req，则该RS为候选RS。其中，上标AP和RS分别表示AP和RS对应的相关参数，如：

分别表示RS、AP的可用带宽，

分别表示RS、AP的连接延时，PER^RS,PER^AP为RS、AP的丢包率，3) Method for determining the candidate RS set: According to the service characteristics of the user in the service perception module and the status information of the AP associated with the RS in the relay information collection module, it is judged whether the AP associated with the RS satisfies the service characteristics of the user. If so, the RS for candidate RS. Determine the available bandwidth of the two-hop link according to the status information of the user's neighboring RS and its associated AP , connection delay

Packet error rate PER_link =max(PER^RS ,PER^AP ), judge whether the link meets the user service characteristics, if B_link ≥ B_req , D_link ≤ D_req , PER_link ≤ PER_req , then the RS is a candidate RS . Among them, the superscripts AP and RS respectively represent the relevant parameters corresponding to AP and RS, such as:

Respectively represent the available bandwidth of RS and AP,

Represents the connection delay of RS and AP respectively, PER^RS , PER^AP is the packet loss rate of RS and AP,

7、接入选择模块：该模块根据信息分析处理模块输出的信息，对新用户的业务特性、候选AP及RS的状态信息进行综合评估，实现接入模式以及最佳AP/RS的选择。7. Access selection module: According to the information output by the information analysis and processing module, this module comprehensively evaluates the service characteristics of new users, the status information of candidate APs and RSs, and realizes the selection of the access mode and the best AP/RS.

8．切换控制模块：该模块主要根据信息分析处理模块输出AP信息，对已接入网络用户当前的各候选AP的综合性能进行评估，实现切换控制的功能。8. Handover control module: This module mainly outputs AP information according to the information analysis and processing module, evaluates the comprehensive performance of each candidate AP currently connected to the network user, and realizes the function of handover control.

9．AP接入模块：根据接入选择模块选择的最佳AP信息，执行AP接入。9. AP access module: perform AP access according to the best AP information selected by the access selection module.

10．中继接入模块：根据接入选择模块选择的最佳RS信息，执行用户通过RS接入AP。10. Relay access module: according to the best RS information selected by the access selection module, execute the user to access the AP through the RS.

11、切换执行模块：根据切换控制模块提供的切换目标AP的信息，执行AP间的切换。11. Handover execution module: perform handover between APs according to the handover target AP information provided by the handover control module.

本发明主要基于各AP的负载状况进行接入选择，AP的负载为各用户已占用带宽总和与AP总带宽之比，对于第i个AP，根据公式：

确定负载，其中，

分别为第i个AP的总带宽及当前可用带宽。具体接入选择方法如下：The present invention mainly carries out access selection based on the load status of each AP, and the load of the AP is the ratio of the sum of bandwidth occupied by each user to the total bandwidth of the AP. For the i-th AP, according to the formula:

Determine the load where,

are the total bandwidth and the current available bandwidth of the i-th AP, respectively. The specific access selection method is as follows:

图5为本发明接入选择方法流程图，具体包括以下步骤：FIG. 5 is a flow chart of the access selection method of the present invention, which specifically includes the following steps:

步骤501：新发起接入网络的用户根据候选AP集中AP数目，判断是否位于多个满足用户业务需求的AP的覆盖范围，选择是否接入AP及接入方式。假设候选AP集中AP数目为M^AP，若M^AP=0，用户没有AP的覆盖范围；若M^AP=1，用户在一个AP的覆盖范围；M^AP>1，用户在多个AP的覆盖范围。Step 501: The user who newly initiates access to the network judges whether it is located in the coverage area of multiple APs that meet the user's business needs according to the number of APs in the candidate AP set, and selects whether to access the AP and the access method. Assuming that the number of APs in the candidate AP set is M^AP , if M^AP =0, the user has no AP coverage; if M^AP =1, the user is in the coverage of one AP; M^AP >1, the user is in the coverage of multiple APs .

步骤502：M^AP>1，则根据各AP的RSS及负载状况，选择接入AP。其中计算网络负载状况方法为：定义AP的负载为各用户已占用带宽总和与AP总带宽之比，对于第i个AP，定义其负载为：

其中，

分别为第i个AP的总带宽及当前可用带宽。令RSS_m为用户接收到来自第m个AP的RSS，L_m为第m个AP的负载值，1≤m≤M^AP，根据Q^AP_m=α₁RSS_m+α₂(1-L_m)，评估各候选AP性能，选择最大Q^AP_m对应的AP作为目标接入AP，其中RSS_th为RSS门限，

为负载门限，α₁，α₂为给定常数，标识RSS及负载状况在AP性能评估中的权重。Step 502: M^AP > 1, then select an access AP according to the RSS and load status of each AP. The method of calculating the network load status is as follows: define the load of the AP as the ratio of the sum of bandwidth occupied by each user to the total bandwidth of the AP. For the i-th AP, define its load as:

in,

are the total bandwidth and the current available bandwidth of the i-th AP, respectively. Let RSS_m be the RSS received by the user from the mth AP, and L_m be the load value of the mth AP, 1≤m≤M^AP , according to Q^AP_m =α₁ RSS_m +α₂ (1-L_m ), evaluate the performance of each candidate AP, and select the AP corresponding to the maximum Q^AP_m as the target access AP, where RSS_th is the RSS threshold,

is the load threshold, α₁ and α₂ are given constants, which identify the weight of RSS and load status in AP performance evaluation.

步骤503：若M^AP=1，且该AP负载低于门限值，则接入该AP。Step 503: If M^AP =1, and the load of the AP is lower than the threshold, access the AP.

503A1：判断该AP负载是否满足

若是，则接入该AP。503A1: Determine whether the AP load is satisfied

If yes, access the AP.

503A2：若否，则转至步骤504。503A2: If not, go to step 504.

若M^AP=0或候选AP不满足负载条件，则检测周围是否存在满足要求的RS，若存在，则触发RS接入模式，用户以多跳方式通过RS接入AP，否则，此次通信请求失败。If M^AP = 0 or the candidate AP does not meet the load conditions, it will detect whether there is an RS that meets the requirements around, and if it exists, trigger the RS access mode, and the user accesses the AP through the RS in a multi-hop manner, otherwise, the communication request fail.

步骤504：若M^AP=0或AP不满足负载条件，则用户检测周围是否存在与AP关联的RS，假设候选RS集中RS数目为N^RS，即判断N^RS是否为0，若是，则此次通信请求失败；若否，转至步骤505。Step 504: If M^AP = 0 or the AP does not meet the load condition, then the user detects whether there are RSs associated with the AP around, assuming that the number of RSs in the candidate RS set is N^RS , that is, it is judged whether N^RS is 0, and if so, this time The communication request fails; if not, go to step 505.

步骤505：判断N^RS是否为1。Step 505: Determine whether N^RS is 1.

505A1：若是，即N^RS=1，用户周围仅存在一个候选RS，需进而判断该RS及其关联的AP是否满足负载需求，若且

，则选择通过该RS接入AP，其中，L^RS及

分别为当前RS的负载及负载门限值，L^AP为该RS当前关联AP负载。505A1: If yes, that is, N^RS = 1, there is only one candidate RS around the user, and it is necessary to determine whether the RS and its associated AP meet the load requirements. If and

, choose to access the AP through the RS, where L^RS and

are the load and load threshold of the current RS respectively, and L^AP is the load of the AP currently associated with the RS.

505A2：若否，即N^RS>1，用户周围存在多个候选RS且RS所关联的AP满足

，则根据各RS的位置、运动速度及其关联AP的负载状况，选择接入某RS。记发起接入用户的位置为(x,y)，以速度v运动，第n个RS的位置为(R_n_x,R_n_y)，以速度R_n_v运动。用户与第n个RS之间链路PER为

，第n个RS与其关联AP之间链路PER为

，则用户经第n个RS与AP相连的链路PER为：

记第n个RS及其关联AP的链路负载值分别为及

，用户经第n个RS与AP相连的链路负载值为

调用${Q^{\mathrm{RS}}}_n={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_n^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_n^{\mathrm{link}},$评估各候选RS性能，选择最小Q^RS_n对应的RS作为目标接入RS。其中

，△v=|R_n_v-v|分别为发起接入用户与RS间的距离与相对速度，R_r为传输范围，P_max为最大可容忍误包率，v_max为车辆最大速度，β₁，β₂，β₃，β₄为给定常数，标识RS与用户间的距离、速度、误包率及负载状况在性能评估中的权重。505A2: If not, that is, N^RS >1, there are multiple candidate RSs around the user and the AP associated with the RS satisfies

, according to the position, movement speed of each RS and the load status of its associated AP, select to connect to a certain RS. Note that the position of the initiating access user is (x, y), moving at a speed v, and the position of the nth RS is (R_n _x, R_n _y), moving at a speed R_n _v. The link PER between the user and the nth RS is

, the link PER between the nth RS and its associated AP is

, then the PER of the link connecting the user to the AP via the nth RS is:

Note that the link load values of the nth RS and its associated AP are and

, the link load of the user connected to the AP via the nth RS is

transfer${Q^{\mathrm{RS}}}_{\mathrm{no}}={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_{\mathrm{no}}^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_{\mathrm{no}}^{\mathrm{link}},$ Evaluate the performance of each candidate RS, and select the RS corresponding to the smallest Q^RS_n as the target access RS. in

, △v=|R_n _v-v| are the distance and relative speed between the initiating access user and the RS, R_r is the transmission range, P_max is the maximum tolerable packet error rate, v_max is the maximum speed of the vehicle, β₁ , β₂ , β₃ , and β₄ are given constants, indicating the distance between RS and users, speed, packet error rate and load status weights in performance evaluation.

图6为本发明切换控制方法流程图，具体包括以下步骤：Fig. 6 is a flow chart of the switching control method of the present invention, which specifically includes the following steps:

切换控制模块根据信息分析处理模块输出AP信息，对已接入网络用户当前的各候选AP的综合性能进行评估，实现切换控制功能。具体切换控制方法如下：已接入AP的用户根据AP信息，周期性评估候选AP集中的RSS及负载状况，若确定邻近AP的RSS及负载性能更优，则启动基于切换的负载均衡机制，执行切换至目标AP。The handover control module outputs AP information according to the information analysis and processing module, evaluates the comprehensive performance of each candidate AP currently connected to the network user, and realizes the handover control function. The specific switching control method is as follows: users who have connected to the AP periodically evaluate the RSS and load status of the candidate AP set according to the AP information. Switch to the target AP.

步骤601：已接入AP的用户根据AP信息，周期性评估候选AP集中的RSS及负载状况。Step 601: The user who has accessed the AP periodically evaluates the RSS and load status of the candidate AP set according to the AP information.

步骤602：判断邻近AP的RSS及负载性能是否更优，若是，则启动基于切换的负载均衡机制。假设第i，j个AP分别为用户当前AP及邻近AP，计算

及

，定义用户切换准则为：

其中，δ₁用于定量描述候选AP及当前AP性能差异，δ₂用于标识目标AP的RSS性能与门限值之间的增量，δ₂的合理选取可有效避免切换的乒乓效应，判断用户当前关联的AP是否满足该切换准则。Step 602: Determine whether the RSS and load performance of neighboring APs are better, and if so, start a handover-based load balancing mechanism. Assuming that the i-th and j-th APs are the user's current AP and neighboring APs respectively, calculate

and

, define the user switching criterion as:

Among them, δ₁ is used to quantitatively describe the performance difference between the candidate AP and the current AP, δ₂ is used to identify the increment between the RSS performance of the target AP and the threshold value, and the reasonable selection of δ₂ can effectively avoid the ping-pong effect of handover. Whether the AP currently associated with the user satisfies the handover criterion.

602A1：若是，则触发AP之间的切换，建立与目标AP的关联，并断开与当前AP之间的数据传输。602A1: If yes, trigger handover between APs, establish an association with the target AP, and disconnect data transmission with the current AP.

602A2：若否，则继续接入当前网络。602A2: If not, continue to access the current network.

若用户评估确定候选AP综合性能优于当前AP，则触发AP之间的切换，建立与目标AP的关联，并断开与当前AP之间的数据传输。对于当前及目标AP属于不同通信子网，用户采用移动IPv6协议实现切换。具体步骤为：If the user evaluates and determines that the overall performance of the candidate AP is better than that of the current AP, it will trigger a switch between APs, establish an association with the target AP, and disconnect the data transmission with the current AP. For the current and target APs belonging to different communication subnets, the user adopts the mobile IPv6 protocol to realize the handover. The specific steps are:

（1）MN接收到外地网络的路由器公告（router advertisement，RA）消息，判断出自己己经移动到了新的网络。若MN未接收到RS消息，则发送路由器请求（router solicitation，RS）消息，请求网络发送RA消息。(1) The MN receives a router advertisement (RA) message from a foreign network and determines that it has moved to a new network. If the MN does not receive the RS message, it sends a router solicitation (RS) message to request the network to send an RA message.

（2）MN根据外地网络的网络前缀通过动态主机配置协议（Dynamic HostConfiguration Protocol，DHCP）或无状态地址配置模式，配置新的转交地址（Careof Address，CoA），并执行重复地址检测。(2) According to the network prefix of the foreign network, the MN configures a new care of address (CoA) through Dynamic Host Configuration Protocol (Dynamic Host Configuration Protocol, DHCP) or stateless address configuration mode, and performs duplicate address detection.

（3）MN向其家乡网络中的代理路由器（Home Agent，HA）发送绑定更新（binding update，BU）消息，告知对方其CoA。(3) The MN sends a binding update (binding update, BU) message to the agent router (Home Agent, HA) in its home network to inform the other party of its CoA.

（4）MN向通信对端（Correspondence Node，CN）发送BU消息，告知对方其CoA。(4) The MN sends a BU message to the correspondent node (Correspondence Node, CN) to inform the other party of its CoA.

（5）HA接收到MN发送来的BU消息，建立或更新MN的绑定缓存项，并向MN返回绑定确认（binding acknowledge，BA）消息，完成“家乡注册”过程。(5) The HA receives the BU message sent by the MN, establishes or updates the binding cache entry of the MN, and returns a binding acknowledgment (binding acknowledgment, BA) message to the MN, completing the "home registration" process.

（6）CN接收到MN发送来的BU消息，建立或更新MN的绑定缓存项，并向MN返回绑定BA消息，完成“对端注册”过程。(6) CN receives the BU message sent by the MN, establishes or updates the MN's binding cache item, and returns the binding BA message to the MN, completing the "peer registration" process.

（7）CN经AR实现与MN的数据传输。对于由MN发送的数据，可通过当前接入路由器直接发送至CN。(7) CN implements data transmission with MN via AR. For the data sent by the MN, it can be directly sent to the CN through the current access router.

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Translated fromChinese

1.一种车联网中支持多跳WLAN的移动用户MN接入终端选择装置，其特征在于，包括：1. A mobile user MN access terminal selection device supporting multi-hop WLAN in the Internet of Vehicles, characterized in that, comprising:监测模块：监测MN所关联接入点AP周期性广播的Beacon消息，监测用户所关联中继节点RS周期性广播的RelayAdv消息，并传送至信息收集模块；Monitoring module: monitor the Beacon message periodically broadcast by the access point AP associated with the MN, monitor the RelayAdv message periodically broadcast by the relay node RS associated with the user, and send it to the information collection module;信息收集模块：根据Beacon消息进行AP信息的收集，根据RelayAdv消息进行RS信息的收集；Information collection module: collect AP information according to Beacon messages, and collect RS information according to RelayAdv messages;业务感知模块：感知用户业务QoS需求；Service perception module: perceive user service QoS requirements;信息分析处理模块：根据信息收集模块及业务感知模块的数据，确定候选AP/RS集，并传送至切换控制模块及接入选择模块；Information analysis and processing module: according to the data of the information collection module and the service perception module, determine the candidate AP/RS set, and send it to the handover control module and the access selection module;接入选择模块：根据信息分析处理模块的信息，对用户的业务特性、候选AP及RS的状态信息进行评估，选择接入模式及最佳AP/RS；Access selection module: according to the information of the information analysis and processing module, evaluate the service characteristics of the user, the status information of candidate APs and RSs, and select the access mode and the best AP/RS;切换控制模块：根据信息分析处理模块输出AP信息，对接入网络用户当前的各候选AP的性能进行评估，若满足切换条件，则执行切换；Handover control module: output AP information according to the information analysis and processing module, evaluate the performance of each candidate AP currently accessed by the network user, and execute the handover if the handover condition is met;接入模块：根据接入选择模块确定的最佳目标AP，执行AP接入，根据确定的最佳目标RS，执行基于RRTS/CRTS的RS接入；Access module: perform AP access according to the best target AP determined by the access selection module, and perform RS access based on RRTS/CRTS according to the determined best target RS;切换执行模块：根据切换控制模块确定的切换目标AP，执行AP间的切换。Handover execution module: execute handover between APs according to the handover target AP determined by the handover control module.2.根据权利要求1所述的选择装置，其特征在于，信息分析处理模块确定候选AP/RS集包括：根据用户邻近AP的状态信息判断该AP是否满足用户业务需求，若满足

PER^AP≤PER_req，则该AP为候选AP；根据用户邻近RS及其所关联AP的状态信息，确定两跳链路可用带宽

连接延时，误包率PER_link=max(PER^RS,PER^AP)，判断该链路是否满足用户业务特性，若B_link≥B_req，D_link≤D_req，PER_link≤PER_req，则该RS为候选RS。2. The selection device according to claim 1, wherein the determination of the candidate AP/RS set by the information analysis processing module includes: judging whether the AP satisfies the service requirements of the user according to the status information of the user's neighboring APs, and if

PER^AP ≤ PER_req , then the AP is a candidate AP; determine the available bandwidth of the two-hop link according to the status information of the user's neighboring RS and its associated AP

connection delay , packet error rate PER_link =max(PER^RS ,PER^AP ), judge whether the link meets the user service characteristics, if B_link ≥ B_req , D_link ≤ D_req , PER_link ≤ PER_req , then the RS is a candidate RS.3.根据权利要求1所述的选择装置，其特征在于，接入模块接入选择具体为：如候选AP集中AP数目为M^AP，若M^AP>1，则根据各AP的RSS及负载状况，选择接入AP；若M^AP=1，且该AP负载低于门限值，则接入该AP；若M^AP=0，则判断候选RS集中是否存在满足业务需求的RS，记候选RS集中RS数目为N^RS，若N^RS>1，则基于RS优化选择方法选择最优接入RS；若N^RS=1，且RS的负载及该RS当前关联AP负载低于负载门限值，则接入该RS；若N^RS=0，则此次通信请求失败。3. The selection device according to claim 1, wherein the access selection of the access module is specifically: if the number of APs in the candidate AP set is M^AP , if M^AP >1, then according to the RSS and load status of each AP , choose to access the AP; if M^AP = 1, and the load of the AP is lower than the threshold value, then access the AP; if M^AP = 0, then determine whether there is an RS in the candidate RS set that meets the service requirements, and record the candidate RS The number of concentrated RSs is N^RS , if N^RS >1, select the optimal access RS based on the RS optimization selection method; if N^RS =1, and the load of the RS and the load of the current associated AP of the RS is lower than the load threshold, Then access the RS; if N^RS =0, then this communication request fails.4.根据权利要求3所述的选择装置，其特征在于，对于M^AP>1，根据Q^AP_m=α₁RSS_m+α₂(1-L_m)，评估各候选AP性能，选择最大Q^AP_m对应的AP作为目标接入AP，其中，L_m为第m个AP的负载值，RSS_m为用户接收到来自第m个AP的RSS，α₁、α₂为标识RSS及负载状况在AP性能评估中的权重。4. The selection device according to claim 3, characterized in that, for M^AP > 1, according to Q^AP_m = α₁ RSS_m + α₂ (1-L_m ), evaluate the performance of each candidate AP, and select the maximum Q The AP corresponding to^AP_m is used as the target access AP, where L_m is the load value of the m-th AP, RSS_m is the RSS received by the user from the m-th AP, α₁ and α₂ are the identification RSS and the load status in Weight in AP performance evaluation.5.根据权利要求3所述的选择装置，其特征在于，基于RS优化选择方法选择最优接入RS具体包括：若N^RS>1，则根据各RS的位置、运动速度及其关联AP的负载状况，选择接入RS，调用${Q^{\mathrm{RS}}}_n={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_n^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_n^{\mathrm{link}},$评估各候选RS性能，选择最小Q^RS_n对应的RS作为目标接入RS，其中，用户与第n个RS之间链路PER为

，第n个RS与其关联AP之间链路PER为

，则用户经第n个RS与AP相连的链路PER为：

第n个RS及其关联AP的链路负载值分别为

及

，用户经第n个RS与AP相连的链路负载值为

△d、△v分别为发起接入用户与RS间的距离与相对速度，R_r为传输范围，P_max为最大可容忍误包率，v_max为车辆最大速度，β₁，β₂，β₃，β₄为标识RS与用户间的距离、速度、误包率及负载状况的权重。5. The selection device according to claim 3, wherein selecting the optimal access RS based on the RS optimization selection method specifically includes: if N^RS >1, then according to the position, movement speed and the associated AP of each RS Load status, select access RS, call${Q^{\mathrm{RS}}}_{\mathrm{no}}={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_{\mathrm{no}}^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_{\mathrm{no}}^{\mathrm{link}},$ Evaluate the performance of each candidate RS, and select the RS corresponding to the smallest Q^RS_n as the target access RS, where the link PER between the user and the nth RS is

, the link PER between the nth RS and its associated AP is

, then the PER of the link connecting the user to the AP via the nth RS is:

The link load values of the nth RS and its associated AP are respectively

and

, the link load of the user connected to the AP via the nth RS is

△d and △v are the distance and relative speed between the initiating access user and RS, R_r is the transmission range, P_max is the maximum tolerable packet error rate, v_max is the maximum speed of the vehicle, β₁ , β₂ , β₃ ,_β4 is the weight for identifying the distance, speed, packet error rate and load status between the RS and the user.6.根据权利要求4所述的选择装置，其特征在于，根据切换控制模块确定切换目标AP具体包括：已接入AP的用户周期性评估候选AP集中的RSS及负载状况，若确定邻近AP的RSS及负载性能更优，则启动基于切换的负载均衡机制，执行切换至目标AP。6. The selection device according to claim 4, wherein the determination of the handover target AP according to the handover control module specifically includes: the user who has accessed the AP periodically evaluates the RSS and load conditions in the candidate AP set, and if it is determined that the adjacent AP If the RSS and load performance are better, start the handover-based load balancing mechanism and perform handover to the target AP.7.一种车联网中支持多跳WLAN的移动用户MN接入终端选择方法，其特征在于，包括：监测模块监测MN所关联接入点AP周期性广播的Beacon消息，监测用户所关联中继节点RS周期性广播的RelayAdv消息，并传送至信息收集模块；信息收集模块根据Beacon消息进行AP信息的收集，根据RelayAdv消息进行RS信息的收集；业务感知模块感知用户业务QoS需求；信息分析处理模块根据信息收集模块及业务感知模块的数据，确定候选AP/RS集，并传送至切换控制模块及接入选择模块；接入选择模块根据信息分析处理模块的信息，对用户的业务特性、候选AP及RS的状态信息进行评估，选择接入模式及最佳AP/RS；切换控制模块根据信息分析处理模块输出AP信息，对接入网络用户当前的各候选AP的性能进行评估，若满足切换条件，则执行切换；接入模块根据接入选择模块确定的最佳目标AP，执行AP接入，根据确定的最佳目标RS，执行基于RRTS/CRTS的RS接入；切换执行模块根据切换控制模块确定的切换目标AP，执行AP间的切换。7. A mobile user MN access terminal selection method supporting multi-hop WLAN in the Internet of Vehicles, characterized in that it includes: a monitoring module monitors the Beacon message broadcast periodically by the access point AP associated with the MN, and monitors the relay associated with the user Node RS periodically broadcasts the RelayAdv message and sends it to the information collection module; the information collection module collects AP information according to the Beacon message, and collects RS information according to the RelayAdv message; the service perception module perceives the user's service QoS requirements; the information analysis and processing module According to the data of the information collection module and the service perception module, determine the candidate AP/RS set, and send it to the handover control module and the access selection module; the access selection module analyzes the user's service characteristics and candidate APs according to the information of the information analysis and processing module and RS status information to evaluate, select the access mode and the best AP/RS; the handover control module outputs AP information according to the information analysis and processing module, and evaluates the performance of each candidate AP currently accessed by the network user, if the handover condition is met , then perform handover; the access module performs AP access according to the best target AP determined by the access selection module, and performs RS access based on RRTS/CRTS according to the determined best target RS; the handover execution module performs the RS access based on the handover control module The determined handover target AP performs handover between APs.8.根据权利要求7所述的选择方法，其特征在于，信息分析处理模块确定候选AP/RS集包括：根据用户邻近AP的状态信息判断该AP是否满足用户业务需求，若满足PER^AP≤PER_req，则该AP为候选AP；根据用户邻近RS及其所关联AP的状态信息，确定两跳链路可用带宽

连接延时

误包率PER_link=max(PER^RS,PER^AP)，判断该链路是否满足用户业务特性，若B_link≥B_req，D_link≤D_req，PER_link≤PER_req，则该RS为候选RS。8. The selection method according to claim 7, wherein the determination of the candidate AP/RS set by the information analysis processing module includes: judging whether the AP satisfies the service requirements of the user according to the status information of the adjacent APs of the user, and if PER^AP ≤ PER_req , then the AP is a candidate AP; determine the available bandwidth of the two-hop link according to the status information of the user's neighboring RS and its associated AP

connection delay

Packet error rate PER_link =max(PER^RS ,PER^AP ), judge whether the link meets the user service characteristics, if B_link ≥ B_req , D_link ≤ D_req , PER_link ≤ PER_req , then the RS is a candidate RS .9.根据权利要求7所述的选择方法，其特征在于，接入模块接入选择具体为：如候选AP集中AP数目为M^AP，若M^AP>1，则根据各AP的RSS及负载状况，选择接入AP；若M^AP=1，且该AP负载低于门限值，则接入该AP；若M^AP=0，则判断候选RS集中是否存在满足业务需求的RS，记候选RS集中RS数目为N^RS，若N^RS>1，则基于RS优化选择方法选择最优接入RS；若N^RS=1，且RS的负载及该RS当前关联AP负载低于负载门限值，则接入该RS；若N^RS=0，则此次通信请求失败。9. The selection method according to claim 7, wherein the access module access selection is specifically: if the number of APs in the candidate AP set is M^AP , if M^AP >1, then according to the RSS and load status of each AP , choose to access the AP; if M^AP = 1, and the load of the AP is lower than the threshold value, then access the AP; if M^AP = 0, then determine whether there is an RS in the candidate RS set that meets the service requirements, and record the candidate RS The number of concentrated RSs is N^RS , if N^RS >1, select the optimal access RS based on the RS optimization selection method; if N^RS =1, and the load of the RS and the load of the current associated AP of the RS is lower than the load threshold, Then access the RS; if N^RS =0, then this communication request fails.10.根据权利要求9所述的选择方法，其特征在于，对于M^AP>1，根据Q^AP_m=α₁RSS_m+α₂(1-L_m)，评估各候选AP性能，选择最大Q^AP_m对应的AP作为目标接入AP，其中，L_m为第m个AP的负载值，RSS_m为用户接收到来自第m个AP的RSS，α₁、α₂为标识RSS及负载状况在AP性能评估中的权重。10. The selection method according to claim 9, characterized in that, for M^AP > 1, according to Q^AP_m = α₁ RSS_m + α₂ (1-L_m ), evaluate the performance of each candidate AP, and select the maximum Q The AP corresponding to^AP_m is used as the target access AP, where L_m is the load value of the m-th AP, RSS_m is the RSS received by the user from the m-th AP, α₁ and α₂ are the identification RSS and the load status in Weight in AP performance evaluation.11.根据权利要求9所述的选择方法，其特征在于，基于RS优化选择方法选择最优接入RS具体包括：若N^RS>1，则根据各RS的位置、运动速度及其关联AP的负载状况，选择接入RS，调用${Q^{\mathrm{RS}}}_n={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_n^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_n^{\mathrm{link}},$评估各候选RS性能，选择最小Q^RS_n对应的RS作为目标接入RS，其中，用户与第n个RS之间链路PER为

，第n个RS与其关联AP之间链路PER为

则用户经第n个RS与AP相连的链路PER为：

第n个RS及其关联AP的链路负载值分别为及，用户经第n个RS与AP相连的链路负载值为

△d、△v分别为发起接入用户与RS间的距离与相对速度，R_r为传输范围，P_max为最大可容忍误包率，v_max为车辆最大速度，β₁，β₂，β₃，β₄为标识RS与用户间的距离、速度、误包率及负载状况的权重。11. The selection method according to claim 9, characterized in that, selecting the optimal access RS based on the RS optimization selection method specifically includes: if N^RS >1, then according to the position, speed of movement of each RS and the relative AP Load status, select access RS, call${Q^{\mathrm{RS}}}_{\mathrm{no}}={\mathrm{\β}}_1\frac{\mathrm{\Δd}}{R_r}+{\mathrm{\β}}_2\frac{\mathrm{\Δv}}{{2v}_{\max }}+{\mathrm{\β}}_3\frac{{\mathrm{PER}}_{\mathrm{no}}^{\mathrm{link}}}{{\mathrm{PER}}_{\max }}+{\mathrm{\β}}_4{L}_{\mathrm{no}}^{\mathrm{link}},$ Evaluate the performance of each candidate RS, and select the RS corresponding to the smallest Q^RS_n as the target access RS, where the link PER between the user and the nth RS is

, the link PER between the nth RS and its associated AP is

Then the PER of the link connecting the user to the AP via the nth RS is:

The link load values of the nth RS and its associated AP are respectively and , the link load of the user connected to the AP via the nth RS is

△d and △v are the distance and relative speed between the initiating access user and RS, R_r is the transmission range, P_max is the maximum tolerable packet error rate, v_max is the maximum speed of the vehicle, β₁ , β₂ , β₃ ,_β4 is the weight for identifying the distance, speed, packet error rate and load status between the RS and the user.12.根据权利要求9所述的选择方法，其特征在于，根据切换控制模块确定切换目标AP具体包括：已接入AP的用户周期性评估候选AP集中的RSS及负载状况，若确定邻近AP的RSS及负载性能更优，则启动基于切换的负载均衡机制，执行切换至目标AP。12. The selection method according to claim 9, wherein the determination of the handover target AP according to the handover control module specifically includes: the user who has accessed the AP periodically evaluates the RSS and load conditions in the candidate AP set, and if it is determined that the adjacent AP If the RSS and load performance are better, start the handover-based load balancing mechanism and perform handover to the target AP.

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