Contextual Beamforming: Exploiting Location and AI for Enhanced Wireless Telecommunication Performance

The pervasive nature of wireless telecommunication has made it the foundation for mainstream technologies like automation, smart vehicles, virtual reality, and unmanned aerial vehicles. As these technologies experience widespread adoption in our daily lives, ensuring the reliable performance of cellular networks in mobile scenarios has become a paramount challenge. Beamforming, an integral component of modern mobile networks, enables spatial selectivity and improves network quality. However, many beamforming techniques are iterative, introducing unwanted latency to the system. In recent times, there has been a growing interest in leveraging mobile users' location information to expedite beamforming processes. This paper explores the concept of contextual beamforming, discussing its advantages, disadvantages and implications. Notably, the study presents an impressive 53% improvement in signal-to-noise ratio (SNR) by implementing the adaptive beamforming (MRT) algorithm compared to scenarios without beamforming. It further elucidates how MRT contributes to contextual beamforming. The importance of localization in implementing contextual beamforming is also examined. Additionally, the paper delves into the use of artificial intelligence schemes, including machine learning and deep learning, in implementing contextual beamforming techniques that leverage user location information. Based on the comprehensive review, the results suggest that the combination of MRT and Zero forcing (ZF) techniques, alongside deep neural networks (DNN) employing Bayesian Optimization (BO), represents the most promising approach for contextual beamforming. Furthermore, the study discusses the future potential of programmable switches, such as Tofino, in enabling location-aware beamforming

B5G 초고밀도 네트워크에서 유연한 이동성 관리 기법

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 박세웅.차세대 모바일 이동통신을 위한 새로운 서비스와 어플리케이션이 등장함에 따라, 사용자들은 기존 시스템 대비 더 높은 전송 속도를 요구한다. 더불어 사용자들은 높은 데이터 전송 속도를 안정적으로 보장 받기를 원한다. 모바일 네트워크 사용자의 데이터 트래픽이 증가할수록 네트워크의 밀집도를 증가시키는 초고밀도 네트워크 (ultra-dense network)에 대한 관심이 높아지고 있다. 그러나 이러한 초고밀도 네트워크 환경에서는 기존 네트워크 대비 핸드오버가 자주 발생하게 되고, 이로 인해 네트워크 성능이 제한되는 문제가 드러나고 있다. 따라서 초고밀도 네트워크의 성능을 극대화하기 위해서는 효율적인 이동성 관리의 중요성이 어느때보다 부각되고 있다. 본 학위논문에서는 초고밀도 네트워크 환경에서 효율적인 이동성 관리를 위하여 다음의 세 가지 전략을 고려한다. 1) MIAB (mobile integrated access and backhaul) 네트워크에서의 이동성 관리, 2) 딥러닝 기반 장애물 예측을 통한 사전적인 핸드오버, 3) 다중 연결 환경에서의 강인한 이동성 관리. 첫째로, MIAB 네트워크에서 사용자의 QoS (quality-of-service)에 심각한 영향을 미치는 핸드오버 지연 시간을 감소시키기 위한 핸드오버 기법을 제안한다. MIAB 네트워크 환경에서 발생할 수 있는 intra-gNB 핸드오버, inter-gNB 핸드오버, 부모 MIAB 노드 핸드오버의 세 가지 핸드오버 케이스를 분류하고, 부모 MIAB 노드와 자녀 MIAB 노드의 속도에 따른 각 핸드오버 케이스 발생 확률 모델을 제시하였다. 또한, 상향링크 컨트롤 플레인 데이터 전송 지연 시간을 분석하였다. 제안하는 핸드오버 기법은 저지연 상향링크 컨트롤 플레인 데이터 전송 기법과 자녀 MIAB 노드의 RACH-less 핸드오버 기법을 포함한다. 시뮬레이션을 통해 제안하는 MIAB 핸드오버 기법이 기존 핸드오버 기법 대비 핸드오버 지연 시간 및 오버헤드 성능보다 매우 뛰어난 것을 확인하였다. 다음으로 안정적인 이동성 관리를 위한 장애물 예측 기반의 사전 핸드오버 (BAPH) 기법을 제시한다. BAPH는 딥러닝 기법을 활용하여 장애물과 차량의 이동성을 예측하고, 특정 차량이 기지국과 LoS (line-of-sight)에 있는지를 예측한다. 예측된 차량의 미래 위치와 장애물의 미래 위치 정보를 이용하여 gNB와 RLF (radio link failure)를 겪기 이전 시점에 다른 gNB로 핸드오버를 수행한다. 제안하는 사전 핸드오버 기법의 성능을 다양한 도로 환경 및 차량 속도를 반영한 시뮬레이션을 통해 평가하였다. 마지막으로 다중 연결 네트워크의 장점을 최대로 끌어내기 위한 안정적인 핸드오버 기법을 제안한다. 앵커 BS와 액티브 BS 집합이 각 모바일 기기마다 설정되는 사용자 중심 초고밀도 네트워크 (UUDN)을 고려한다. 앵커 BS는 주변 BS들의 RACH 오케스트레이션을 통하여 모바일 기기가 핸드오버를 위해 전송하는 RACH 프리앰블을 다수의 BS가 받을 수 있도록 한다. 또한 핸드오버 과정에서 하나의 액티브 BS에 RLF가 발생하는 경우 핸드오버 과정을 지속하여 빠르게 RLF를 복구하는 기법을 제안한다. 시뮬레이션을 통해 제안하는 핸드오버 기법이 RLF 지속 시간을 현재 핸드오버 기법 대비 줄이는 것을 확인하였으며, 연결 수가 증가하는 경우에 RLF 지속 기간을 더 감소시키는 것을 확인하였다. 요약하면, 차세대 모바일 네트워크에서 이동성 관리와 관련된 새로운 네트워크 구조 및 프로토콜에 대한 문제를 제기한다. 현재 이동성 관리 기법이 고이동성 환경이나 초고밀도 네트워크 환경에서 네트워크의 성능을 저하시키는 것을 확인하였다. 따라서 차세대 모바일 네트워크 시스템에서의 새로운 이동성 관리 기법 및 전략을 제안한다. 제안하는 모든 이동성 관리 기법은 시뮬레이션 결과를 통해 성능을 평가되었다.As new services and applications for next-generation mobile communication emerge, users of mobile communication systems require a higher data rate than the existing system. In addition, mobile communication users want a high data rate to be reliably guaranteed anytime, anywhere. As data traffic of mobile network users increases, ultra-dense networks (UDN) that increase network density are in the limelight. However, in such a UDN environment, handovers (HOs) occur more frequently than in the existing mobile network system, which limits network performance. Therefore, to maximize the performance of the UDN, the importance of efficient mobility management is being emphasized more than ever. In this dissertation, the following three strategies are considered for efficient mobility management in the UDN environment: 1) Mobility management in mobile integrated access and backhaul (MIAB) networks, 2) Proactive HO through blockage prediction based on deep learning technology, 3) Reliable HO using the anchor node in the multi-connectivity environment. First, we propose a novel handover (HO) scheme for the MIAB network to reduce handover interruption time (HIT) and radio link failure (RLF) that have a significant impact on users' quality of service (QoS). We investigate HO cases that cover intra-gNB HO, inter-gNB HO, and parent MIAB node HO and develop their probabilistic models according to the velocities of the parent MIAB node and the child MIAB node. In addition, we investigate the latency in uplink (UL) control plane (CP) data transmission and each HO case for the baseline MIAB network. Our proposed HO scheme consists of low-latency UL CP data transmission with semi-persistent resource pre-allocation and RACH-less HO procedure for child MIAB nodes. Through simulation, we verify our proposed MIAB HO scheme outperforms the baseline HO scheme in terms of HO delay and HO overhead. Second, we propose the blockage-aware proactive HO (BAPH) scheme to support reliable mobility management. BAPH leverages a deep neural network (DNN) to predict the mobility of blockages and which BSs will be in the line-of-sight (LoS) with the vehicle device. With the predicted future blockage locations, the network supports proactive HO to the target gNB before radio link failure (RLF) occurs with the current serving gNB. We evaluate the performance of the proposed proactive HO scheme through simulations in various road environments. Finally, a reliable HO scheme that fully leverages the advantage of the multi-connectivity network is proposed. We consider a user-centric UDN (UUDN) architecture composed of an anchor BS and active BSs set for each UE. The anchor BS orchestrates the RACH of neighbor BSs that are not included in the active BS set for the target UE so that multiple target BSs can receive the RACH preamble transmitted by the UE. In addition, we propose a fast RLF recovery scheme that allows the existing HO process to continue when RLF occurs in the serving BS included in the active BS set. Through simulation, the performance of the proposed HO scheme is verified that the RLF duration of the UE is reduced compared to the current HO scheme even when the number of connections increases in a multi-connectivity environment. In summary, we claim issues in the new network architecture and protocols for the next-generation mobile networks related to mobility management. We demonstrate that the existing mobility management schemes limit the network performance in high-mobility environments and UDN environments. Therefore, we propose new mobility management schemes and strategies for the future mobile network system. All the proposed mobility management schemes are evaluated with simulation results.1 Introduction 1 1.1 Vision of B5G and Challenges 1 1.1.1 Vision of B5G Networks and Services 1 1.1.2 Research Trends and Challenges 2 1.2 Motivation 3 1.3 Main Contributions 5 1.3.1 Mobile Integrated Access and Backhaul Handover 5 1.3.2 Blockage Prediction-based Proactive Handover 6 1.3.3 Mobility Management in Distributed User-centric Ultra-dense Network 7 1.4 Organization of the Dissertation 7 2 Mobility Management of Multi-hop Mobile Integrated Access and Backhaul Network 9 2.1 Introduction 9 2.1.1 Contributions 11 2.1.2 Organization 12 2.2 Preliminary Study 12 2.2.1 IAB Network and Moving Cells 12 2.2.2 5G NR Handover 13 2.2.3 Motivation 14 2.3 System Model 15 2.3.1 Network Model 15 2.3.2 Communication Model 15 2.3.3 Directional Beamforming Model 16 2.3.4 Handover Model 18 2.4 Analysis of Mobility Management in MIAB Networks 18 2.4.1 UL CP Data Transmission Latency 19 2.4.2 Handover Latency 21 2.4.3 Handover Probability 23 2.5 Proposed Mobile IAB Handover Scheme 27 2.5.1 Low-Latency UL CP Data Transmission Scheme 27 2.5.2 Inter-gNB Handover Scheme 29 2.6 Performance Evaluation 31 2.6.1 HO Probability 33 2.6.2 Handover Latency 34 2.6.3 Effective Spectral Efficiency 37 2.7 Summary 41 3 Blockage-aware Proactive Handover for mmWave V2I Communications 42 3.1 Introduction 42 3.2 Preliminaries and Motivation 44 3.2.1 Effect of Blockages in mmWave Systems 44 3.2.2 DNN based Network Prediction 46 3.2.3 Motivation 46 3.3 Analysis on Blockage Effect 47 3.4 Proposed BAPH System 51 3.4.1 System Architecture 51 3.4.2 Communication Model 51 3.4.3 Deep Learning-based Location Prediction 52 3.4.4 Unobserved Blockage Detection and Estimation 54 3.4.5 Proactive Handover Process 57 3.6 Performance Evaluation 58 3.7 Summary 62 4 Anchor Node Based Reliable Handover in User-centric Ultra-dense Network 64 4.1 Introduction 64 4.2 Motivation 65 4.2.1 HO Process in 5G NR 65 4.2.2 HO Failure in the Baseline HO Scheme 66 4.3 Proposed Distributed User-centric Ultra-Dense Network Architecture 69 4.4 Anchor Node-based Mobility Management 71 4.5 Performance Evaluation 73 4.6 Summary 75 5 Concluding Remarks 76 5.1 Research Contributions 76 5.2 Future Research Directions 77 Abstract (In Korean) 85박

The Potential Short- and Long-Term Disruptions and Transformative Impacts of 5G and Beyond Wireless Networks: Lessons Learnt from the Development of a 5G Testbed Environment

The capacity and coverage requirements for 5 th generation (5G) and beyond wireless connectivity will be significantly different from the predecessor networks. To meet these requirements, the anticipated deployment cost in the United Kingdom (UK) is predicted to be between £30bn and £50bn, whereas the current annual capital expenditure (CapEX) of the mobile network operators (MNOs) is £2.5bn. This prospect has vastly impacted and has become one of the major delaying factors for building the 5G physical infrastructure, whereas other areas of 5G are progressing at their speed. Due to the expensive and complicated nature of the network infrastructure and spectrum, the second-tier operators, widely known as mobile virtual network operators (MVNO), are entirely dependent on the MNOs. In this paper, an extensive study is conducted to explore the possibilities of reducing the 5G deployment cost and developing viable business models. In this regard, the potential of infrastructure, data, and spectrum sharing is thoroughly investigated. It is established that the use of existing public infrastructure (e.g., streetlights, telephone poles, etc.) has a potential to reduce the anticipated cost by about 40% to 60%. This paper also reviews the recent Ofcom initiatives to release location-based licenses of the 5G-compatible radio spectrum. Our study suggests that simplification of infrastructure and spectrum will encourage the exponential growth of scenario-specific cellular networks (e.g., private networks, community networks, micro-operators) and will potentially disrupt the current business models of telecommunication business stakeholders - specifically MNOs and TowerCos. Furthermore, the anticipated dense device connectivity in 5G will increase the resolution of traditional and non-traditional data availability significantly. This will encourage extensive data harvesting as a business opportunity and function within small and medium-sized enterprises (SMEs) as well as large social networks. Consequently, the rise of new infrastructures and spectrum stakeholders is anticipated. This will fuel the development of a 5G data exchange ecosystem where data transactions are deemed to be high-value business commodities. The privacy and security of such data, as well as definitions of the associated revenue models and ownership, are challenging areas - and these have yet to emerge and mature fully. In this direction, this paper proposes the development of a unified data hub with layered structured privacy and security along with blockchain and encrypted off-chain based ownership/royalty tracking. Also, a data economy-oriented business model is proposed. The study found that with the potential commodification of data and data transactions along with the low-cost physical infrastructure and spectrum, the 5G network will introduce significant disruption in the Telco business ecosystem

6G Wireless Systems: Vision, Requirements, Challenges, Insights, and Opportunities

Mobile communications have been undergoing a generational change every ten years or so. However, the time difference between the so-called "G's" is also decreasing. While fifth-generation (5G) systems are becoming a commercial reality, there is already significant interest in systems beyond 5G, which we refer to as the sixth-generation (6G) of wireless systems. In contrast to the already published papers on the topic, we take a top-down approach to 6G. We present a holistic discussion of 6G systems beginning with lifestyle and societal changes driving the need for next generation networks. This is followed by a discussion into the technical requirements needed to enable 6G applications, based on which we dissect key challenges, as well as possibilities for practically realizable system solutions across all layers of the Open Systems Interconnection stack. Since many of the 6G applications will need access to an order-of-magnitude more spectrum, utilization of frequencies between 100 GHz and 1 THz becomes of paramount importance. As such, the 6G eco-system will feature a diverse range of frequency bands, ranging from below 6 GHz up to 1 THz. We comprehensively characterize the limitations that must be overcome to realize working systems in these bands; and provide a unique perspective on the physical, as well as higher layer challenges relating to the design of next generation core networks, new modulation and coding methods, novel multiple access techniques, antenna arrays, wave propagation, radio-frequency transceiver design, as well as real-time signal processing. We rigorously discuss the fundamental changes required in the core networks of the future that serves as a major source of latency for time-sensitive applications. While evaluating the strengths and weaknesses of key 6G technologies, we differentiate what may be achievable over the next decade, relative to what is possible.Comment: Accepted for Publication into the Proceedings of the IEEE; 32 pages, 10 figures, 5 table

A Survey on Cellular-connected UAVs: Design Challenges, Enabling 5G/B5G Innovations, and Experimental Advancements

As an emerging field of aerial robotics, Unmanned Aerial Vehicles (UAVs) have gained significant research interest within the wireless networking research community. As soon as national legislations allow UAVs to fly autonomously, we will see swarms of UAV populating the sky of our smart cities to accomplish different missions: parcel delivery, infrastructure monitoring, event filming, surveillance, tracking, etc. The UAV ecosystem can benefit from existing 5G/B5G cellular networks, which can be exploited in different ways to enhance UAV communications. Because of the inherent characteristics of UAV pertaining to flexible mobility in 3D space, autonomous operation and intelligent placement, these smart devices cater to wide range of wireless applications and use cases. This work aims at presenting an in-depth exploration of integration synergies between 5G/B5G cellular systems and UAV technology, where the UAV is integrated as a new aerial User Equipment (UE) to existing cellular networks. In this integration, the UAVs perform the role of flying users within cellular coverage, thus they are termed as cellular-connected UAVs (a.k.a. UAV-UE, drone-UE, 5G-connected drone, or aerial user). The main focus of this work is to present an extensive study of integration challenges along with key 5G/B5G technological innovations and ongoing efforts in design prototyping and field trials corroborating cellular-connected UAVs. This study highlights recent progress updates with respect to 3GPP standardization and emphasizes socio-economic concerns that must be accounted before successful adoption of this promising technology. Various open problems paving the path to future research opportunities are also discussed.Comment: 30 pages, 18 figures, 9 tables, 102 references, journal submissio

On the Road to 6G: Visions, Requirements, Key Technologies and Testbeds

Fifth generation (5G) mobile communication systems have entered the stage of commercial development, providing users with new services and improved user experiences as well as offering a host of novel opportunities to various industries. However, 5G still faces many challenges. To address these challenges, international industrial, academic, and standards organizations have commenced research on sixth generation (6G) wireless communication systems. A series of white papers and survey papers have been published, which aim to define 6G in terms of requirements, application scenarios, key technologies, etc. Although ITU-R has been working on the 6G vision and it is expected to reach a consensus on what 6G will be by mid-2023, the related global discussions are still wide open and the existing literature has identified numerous open issues. This paper first provides a comprehensive portrayal of the 6G vision, technical requirements, and application scenarios, covering the current common understanding of 6G. Then, a critical appraisal of the 6G network architecture and key technologies is presented. Furthermore, existing testbeds and advanced 6G verification platforms are detailed for the first time. In addition, future research directions and open challenges are identified for stimulating the on-going global debate. Finally, lessons learned to date concerning 6G networks are discussed