Link Level Analysis of NR V2X Sidelink Communications

The Internet of Vehicles (IoV) will interconnect vehicles, vulnerable road users, and infrastructure nodes for a safer, more efficient, and digitalized mobility. In the IoV vision, traditional network-based communications will be complemented with direct Sidelink (SL) Vehicle-to-Everything (V2X) communications. To this aim, 3GPP introduced in Release 16 the New Radio (NR) V2X SL technology. The NR V2X SL standard includes important Physical (PHY) layer novelties with respect to LTE V2X SL and NR Uplink/Downlink, and is characterized by a large set of configurable parameters. However, existing NR V2X SL link level studies focus on a confined set of configurations. This limits a thorough understanding of the NR V2X SL link level performance and impacts the accuracy of system level evaluations, which typically leverage link level models to accurately represent the PHY layer performance. These models are based on Look-Up Tables (LUTs) that map the link level performance, e.g., BLock Error Rate (BLER), as a function of the link quality, e.g., Signalto-Noise Ratio (SNR). This study presents an exhaustive NR V2X SL link level evaluation that analyzes the impact of relevant PHY layer aspects, e.g., modulation and coding scheme, channel model, and transmitter-receiver relative speed, considering the wide set of configurations recommended by 3GPP and ETSI. The obtained standard-compliant LUTs are openly released, representing the largest NR V2X SL link level dataset available. The released dataset represents a valuable asset for the community, as it allows exhaustive NR V2X SL system level investigations under a broad range of settings and configurations

LTE/NR V2X Communication Modes and Future Requirements of Intelligent Transportation Systems Based on MR-DC Architectures

[EN] This paper deals with the potential of Third Generation Partnership (3GPP) Project mobile cellular standards to enable vehicular communications. Starting from 3GPP Release 15, and Release 16 specifications for Vehicle-to-Everything (V2X) communications, the different communication modes, interfaces and use cases for V2X based on Long Term Evolution (LTE) and New Radio (NR) are analyzed. This research also studies the potential beneficial impact on V2X of a network that is aware of the underlying Multi-RAT Dual Connectivity (MR-DC) architecture. The methodology followed in this work consists of a review of 3GPP standards for vehicular communications based on mobile networks. The performance evaluation of the communication modes was performed through simulations taking into account resource allocation schemes, packet transmission frequencies, packet size, vehicle density and other parameters defined in the standard. In order to perform simulations of the decentralized communication mode (mode 4), a simulator based on OMNeT++ was configured. For the centralized mode (mode 3), an analytical model in MATLAB was used to configure different simulation scenarios. The results obtained indicate that LTE networks can only support basic V2X use cases because they do not demand strict potential requirements. Simulations showed that the centralized mode offers better performance than mode 4; however, it requires cellular network coverage. More advanced use cases are key for a future Intelligent Transport System (ITS), high-performance networks (i.e., Fifth Generation (5G), NR) are expected to coexist gradually with LTE in the V2X landscape. Therefore, in order to meet the strict requirements for latency, transmission speed and reliability, MR-DC architectures combining different radio access technologies, communication modes and connection interfaces should be deployed. In addition, operation in multi-operator and cross-border scenarios must be guaranteed.This research was supported by the European Union's H2020-ICT-18-2018 action "5G for cooperative, connected and automated mobility", for project "5G for Connected and Automated Road Mobility in the European unioN (5G-CARMEN)" under grant agreement no. 825012.González, EE.; Garcia-Roger, D.; Monserrat Del Río, JF. (2022). LTE/NR V2X Communication Modes and Future Requirements of Intelligent Transportation Systems Based on MR-DC Architectures. Sustainability. 14(7):1-19. https://doi.org/10.3390/su1407387911914

셀룰러 사이드링크 성능 향상을 위한 상위계층 기법

학위논문 (박사) -- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2020. 8. 박세웅.In typical cellular communications, User Equipments (UEs) have always had to go through a Base Station (BS) to communicate with each other, e.g., a UE transmits a packet to a BS via uplink and then the BS transmits the packet to another UE via downlink. Although the communication method can serve UEs efficiently, the communication method can cause latency problems and overload problems in BS. Thus, sidelink has been proposed to overcome these problems in 3GPP release 12. Through sidelink, UEs can communicate directly with each other. There are two representative communications using sidelink, i.e., Device-to-Device (D2D) communication and Vehicle-to-Vehicle (V2V) communication. In this dissertation, we consider three strategies to enhance the performances of D2D and V2V communications: (i) efficient feedback mechanism for D2D communications, (ii) context-aware congestion control scheme for V2V communication, and (iii) In-Device Coexistence (IDC)-aware LTE and NR sidelink resource allocation scheme. Firstly, in the related standard, there is no feedback mechanism for D2D communication because D2D communications only support broadcast-type communications. A feedback mechanism is presented for D2D communications. Through our proposed mechanism, UEs can use the feedback mechanism without the help of BS and UEs do not need additional signals to allocate feedback resources. We also propose a rate adaptation algorithm, which consider in-band emission problem, on top of the proposed feedback mechanism. We find that our rate adaptation achieves higher and stable throughput compared with the legacy scheme that complies to the standard. Secondly, we propose a context-aware congestion control scheme for LTE-V2V communication. Through LTE-V2V communication, UEs transmit Cooperative Awareness Message (CAM), which is a periodic message, and Decentralized Environmental Notification Message (DENM), which is a event-driven message and allows one-hop relay. The above two messages have different characteristics and generation rule. Thus, it is difficult and inefficient to apply the same congestion control scheme to two messages. We propose a congestion control schemes for each message. Through the proposed congestion control schemes, UEs decide whether to transmit according to their situation. Through simulation results, we show that our proposed schemes outperform comparison schemes as well as the legacy scheme. Finally, we propose a NR sidelink resource allocation scheme based on multi-agent reinforcement learning, which awares a IDC problem between LTE and NR in Intelligent Transport System (ITS) band. First, we model a realistic IDC interference based on spectrum emission mask specified at the standard. Then, we formulate the resource allocation as a multi-agent reinforcement learning with fingerprint method. Each UE achieves its local observation and rewards, and learns its policy to increase its rewards through updating Q-network. Through simulation results, we observe that the proposed resource allocation scheme further improves Packet Delivery Ratio (PDR) performances compared to the legacy scheme.전형적인 셀룰러 통신에서는, 단말들은 서로 통신하기 위해 항상 기지국을 거쳐야 한다. 예를 들면, 단말이 uplink를 통해 기지국에게 패킷을 전송한 다음 기지국은 downlink를 통해 해당 패킷을 전송해준다. 이러한 통신방식은 단말들에게 효율적으로 서비스를 제공할 수 있지만, 상황에 따라서는 지연문제와 기지국의 과부하 문제를 야기할 수 있다. 따라서 3GPP release12에서 이러한 문제점들을 극복하기 위해 sidelink가 제안되었다. 덕분에 단말들은 sidelink를 통해서 서로 직접 통신을 할 수 있게 되었다. Sidelink를 사용하는 두 가지 대표적인 통신은 D2D(Device-to-Device) 통신과 V2V(Vehicle-to-Vehicle) 통신이다. 본 논문에서는 D2D 와 V2V 통신 성능을 향상시키기 위한 세가지 전략을 고려한다. (i) D2D 통신을 위한 효율적인 피드백 메커니즘, (ii) V2V 통신을 위한 상황인식기반 혼잡제어 기법, 그리고 (iii) IDC(In-Device Coexistence) 인지 기반 sidelink 자원 할당 방식. 첫째, 관련 표준에는 D2D 통신이 브로드캐스트 유형의 통신만을 지원하기 때문에 D2D 통신에 대한 피드백 메커니즘이 없다. 우리는 이러한 한계점을 극복하고자 D2D 통신을 위한 피드백 메커니즘을 제안한다. 제안된 메커니즘을 통해, 단말은 기지국의 도움없이 피드백 메커니즘을 사용할 수 있으며 피드백 자원을 할당하기 위한 추가 신호를 필요로 하지 않는다. 우리는 또한 제안된 피드백 메커니즘위에서 동작할 수 있는 data rate 조절 기법을 제안하였다. 우리는 시뮬레이션 결과를 통하여, 제안한 data rate 조절 기법이 기존 방식보다 더 높고 안정적인 수율을 제공하는 것을 확인하였다. 둘째, LTE-V2V 통신을 위한 상황 인지 기반 혼잡 제어 기법을 제안한다. LTE-V2V 통신에서 단말들은 주기적인 메시지인 CAM(Cooperative Awareness Message) 및 비주기적 메시지이며 one-hop릴레이를 허용하는 DENM(Decentralized Environmental Notification Message)를 전송한다. 위의 두 메시지는 특성과 생성 규칙이 다르기 때문에 동일한 혼잡 제어 기법을 적용하는 것은 비효율적이다. 따라서 우리는 각 메시지에 적용할 수 있는 혼잡 제어 기법들을 제안한다. 제안된 기법들을 통해서 단말들은 그들의 상황에 따라서 전송 여부를 결정하게 된다. 시뮬레이션 결과를 통해 제안된 기법이 기존 표준 방식 뿐만 아니라 최신의 비교 기법들보다 우수한 성능을 얻는 것을 확인하였다. 마지막으로 ITS(Intelligent Transport System)대역에서 LTE와 NR사이의 IDC문제를 고려하는 NR sidelink 자원할당 기법을 제안한다. 먼저, 표준에 지정된 스펙트럼 방출 마스크를 기반으로 현실적인 IDC 간섭을 모델링한다. 그런 다음 다중 에이전트 강화학습으로 자원할당 기법을 제안한다. 각 단말들은 자신들의 주변 환경을 관측하고 관측된 환경을 기반으로 행동하여 보상을 얻고 Q-network을 자신의 보상을 증가시키도록 정책을 업데이트 및 학습한다. 우리는 시뮬레이션 결과를 통하여 제안된 자원할당 박식이 기존기법 대비하여 PDR(Packet Delivery Ratio) 성능을 향상시키는 것을 확인하였다.Introduction 1 Efficient feedback mechanism for LTE-D2D Communication 8 CoCo: Context-aware congestion control scheme for C-V2X communications 35 IDC-aware resource allocation based on multi-agents reinforcement learning 67 Concluding remarks 84 Abstract(In Korean) 96 감사의 글 99Docto

On the Role of 5G and Beyond Sidelink Communication in Multi-Hop Tactical Networks

This work investigates the potential of 5G and beyond sidelink (SL) communication to support multi-hop tactical networks. We first provide a technical and historical overview of 3GPP SL standardization activities, and then consider applications to current problems of interest in tactical networking. We consider a number of multi-hop routing techniques which are expected to be of interest for SL-enabled multi-hop tactical networking and examine open-source tools useful for network emulation. Finally, we discuss relevant research directions which may be of interest for 5G SL-enabled tactical communications, namely the integration of RF sensing and positioning, as well as emerging machine learning tools such as federated and decentralized learning, which may be of great interest for resource allocation and routing problems that arise in tactical applications. We conclude by summarizing recent developments in the 5G SL literature and provide guidelines for future research.Comment: 6 pages, 4 figures. To be presented at 2023 IEEE MILCOM Workshops, Boston, M

Performance Analysis of Sidelink 5G-V2X Mode 2 through an Open-Source Simulator

The Third Generation Partnership Project (3GPP) has recently published a new set of specifications to enable advanced driving applications in fifth generation (5G) vehicle-to-everything (V2X) scenarios, with particular effort dedicated to the sidelink resource allocation in the autonomous mode, named Mode 2. In this paper, we conduct a comprehensive analysis of Mode 2 performance via an open-source system-level simulator, which implements the 5G New Radio (NR) flexible numerology and physical layer aspects together with the newly specified sidelink resource allocation modes for V2X communications and different data traffic patterns. Results collected through extensive simulation campaigns, under a wide variety of vehicle density, data transmission settings and traffic patterns, showcase the effects of the new 5G-V2X features on the sidelink resource allocation performance and provide some insights into possible ways to further improve Mode 2 performance

Study of BSM Inter-Packet Gap Tails in C-V2X Networks

Cellular vehicle-to-everything (C-V2X) enables safety-critical connected vehicular service by exchanging basic safety messages (BSMs) among nearby vehicular users (VUEs). Timely transmission of BSMs is crucial to avoid stale information at VUEs. However, successive packet losses can lead to large inter-packet gaps (IPGs), reducing the BSMs' reliability. This paper investigates the tail behavior of IPG and information age (IA) distributions in C-V2X mode 4, a decentralized resource allocation method based on semi-persistent scheduling (SPS). We study the improvements and trade-offs introduced by SAE one-shot transmission to decrease the number of successive BSM losses at destination VUEs. The study employs high-fidelity system-level simulations that closely follow the SPS process of CV2X mode 4 to evaluate the performance of interleaved one-shot SPS transmissions. The numerical results demonstrate significant improvement in the IPG and IA tail distributions in various simulation scenarios. Additionally, we propose an accurate analytical model to characterize the IPG tail behavior of C-V2X BSM transmissions. The proposed model is validated by comparing its results with those obtained using the system-level simulations. Our validation shows that the proposed model generates analytical results that coincide with the asymptotic slopes of IPG distribution in different BSM transmission modes.Comment: arXiv admin note: substantial text overlap with arXiv:2110.0005

Performance Analysis of the Cellular-V2X Mode 4

This TFM intends to explore the V2X communication capabilities for 5G systems, starting from the V2X sidelink defined in LTE Rel. 14 and including the most recent advances for 5G NR currently considered by recent release 16. The project targets to analyze the different simulation tools that are available for assessing the performance of V2X communications and to carry out a performance assessment of the technology.Vehicular communications are becoming a reality and are necessary to improve safety driving conditions. The objective of this thesis is to introduce the basic concepts of Cellular-V2X Mode 4 and analyze its performance in terms of channel busy ratio (CBR) and packet delivery ratio (PDR) under different scenarios and configurations. A C-V2X Mode 4 Simulator has been used to check the impact of different parameters such as the transmission rate, modulation and coding scheme, transmission power, subchannelization or probability of keeping the granted resources among others. Two different scenarios have been considered, a fast highway and a congested highway with low speed and high vehicle traffic congestion. The results have revealed relevant differences in terms of PDR between both scenarios. The main causes of failure, the delay and CBR have been also analyzed. The transmission rate is the parameter that most influences the overall performance of the network. In some cases such as the congested highway scenario, obtained performance has revealed some limitations of the technology, e.g. in terms of PDR... and it is expected that with the new capacities of 5G NR it could be improved

5G NR sidelink on UE protocol stack

Abstract. The idea of effcient communication outside of coverage of base stations have been discussed for a long time. The most suitable solution for this idea has been the ability to extend the communication through devices. In theory, it would be necessary for just one device to be in the coverage of the base station, and the communication could be further extended by hopping from device to device. These communications are called device-to-device communications. Multiple different technologies could be used to solve this task, such as Wi-Fi, Bluetooth and sidelink. Especially when it comes to high mobility and reliability dependent use cases, technologies such as Wi-Fi are simply not capable. This is where the sidelink technology comes in. The sidelink is a communication technology that allows devices to communicate with each other directly, without the need for a cellular network. This technology utilizes the frequency spectrum and enables high-speed, low-latency communication between devices. It has numerous potential applications, including vehicle-to-vehicle communication, machine-type communication, and local area networking. In this thesis, technical characteristics of 5G NR sidelink and its potential applications and challenges are considered. The overview of the ongoing standardization efforts and the deployment status of this technology are discussed. The effciency of the sidelink technology is evaluated and compared to the existing technologies. The sidelink related future updates are discussed and their effect on the current specifcation is evaluated.5G NR sidelink -käyttäjäpäätteen protokollapino. Tiivistelmä. Tukiasemien kantavuuden ulkopuolelle yltävistä verkkoyhteyksistä on keskusteltu jo pitkään. Potentiaalisesti toimivin ratkaisu olisi kasvattaa kantavuutta kannettavien laitteiden kautta. Teoriassa tukiaseman kantaman sisällä tarvitaan vain yksi laite, jonka avulla yhteys voitaisiin kuljettaa laitteelta toiselle tukiaseman kantaman ulkopuolella. Tämänlaisia yhteyksiä kutsutaan suoriksi laitteelta laitteelle yhteyksiksi. Kyseiset yhteydet voitaisiin toteuttaa useilla eri teknologioilla, kuten Wi-Fi:llä, Bluetooth:lla tai sidelink:llä. Erityisesti suurta liikkuvuutta ja luotettavuutta vaativiin käyttökohteisiin Wi-Fi ei ole riittävän tehokas. Tämänlaisissa käyttökohteissa sidelink voisi toimia sopivana Wi-Fi:n korvaajana. Sidelink-teknologia antaa laitteille mahdollisuuden kommunikoida suoraan toistensa kanssa. Nämä yhteydet eivät vaadi matkapuhelinverkkoa toimiakseen. Sidelink-teknologialla mahdollistetaan nopeat, luotettavat ja matalan latenssin yhteydet laitteiden välillä. Sidelink mahdollistaa useita moderneja käyttökohteita, kuten ajoneuvojen väliset yhteydet. Tässä diplomityössä sidelinkin ominaisuuksia käydään läpi. Potentiaalisia sovellutuksista ja teknologiaan liittyvistä haasteista keskustellaan. Käynnissä olevat standardisoinnit käydään tärkeimmiltä osiltaan läpi. Sidelink-teknologian toimivuutta verrataan olemassa oleviin vastaaviin teknologioihin. Myös LTE ja NR versioiden eroja käydään läpi. Myös tulevia muutoksia ja standardisointeja tarkastellaan