Comparing the bandwidths of a crossed spherical helix antenna (XSHA) and conventional antennas is challenging owing to significant change in the radiation efficiency with respect to frequency even at low voltage standing wave ratio (VSWR). Thus, two types of evaluation were performed in this work to demonstrate the wideband property of XSHA. First, the antennas were assumed to be made of a perfect conductor and were compared regarding only the VSWR bandwidth. Next, we compared the bandwidth at radiation efficiency of lossy antennas based on the generalized effective fractional bandwidth $(B_{e}). B_{e}$ is the product of the bandwidth and the radiation efficiency varying with frequency. Numerical simulations were conducted to compare the bandwidths for $VSWR leq 3$ . The bandwidth of the XSHA is 2.19 and 2.11 times wider than those of single resonance antenna in lossless and lossy cases, respectively. Compared with a dual resonance antenna, the bandwidth of the XSHA is 1.36 times greater at acceptable radiation efficiencies of 50%.
{"title":"Two Types of Bandwidth Evaluation of Crossed Spherical Helix Antennas Using Numerical Simulation","authors":"Takuma Shimada;Mina Nishie;Keisuke Noguchi;Masato Odagaki;Keisuke Fujita","doi":"10.23919/comex.2024XBL0038","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0038","url":null,"abstract":"Comparing the bandwidths of a crossed spherical helix antenna (XSHA) and conventional antennas is challenging owing to significant change in the radiation efficiency with respect to frequency even at low voltage standing wave ratio (VSWR). Thus, two types of evaluation were performed in this work to demonstrate the wideband property of XSHA. First, the antennas were assumed to be made of a perfect conductor and were compared regarding only the VSWR bandwidth. Next, we compared the bandwidth at radiation efficiency of lossy antennas based on the generalized effective fractional bandwidth \u0000<tex>$(B_{e}). B_{e}$</tex>\u0000 is the product of the bandwidth and the radiation efficiency varying with frequency. Numerical simulations were conducted to compare the bandwidths for \u0000<tex>$VSWR leq 3$</tex>\u0000. The bandwidth of the XSHA is 2.19 and 2.11 times wider than those of single resonance antenna in lossless and lossy cases, respectively. Compared with a dual resonance antenna, the bandwidth of the XSHA is 1.36 times greater at acceptable radiation efficiencies of 50%.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 9","pages":"351-354"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554804","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142091062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Intelligent reflecting surface (IRS), which can reflect radio waves controlling the phase of incident radio waves, is being investigated for wireless communication in high-frequency bands. To control the reflection characteristic, it is necessary to separately estimate a large number of channel coefficients between transmitting and receiving antennas through each IRS element. This causes significant overhead for the channel estimation. We have proposed a channel prediction method to reduce the overhead using Gaussian process regression with spectral mixture kernel. In Gaussian process regression, the determination of the hyperparameters used to calculate the kernel matrix has a significant impact on prediction accuracy. In this study, we propose validation-based hyperparameter determination for GPR-based channel prediction and evaluate the performance difference between the gradient method and validation.
{"title":"On Hyperparameter Determination for GPR-Based Channel Prediction in IRS-Assisted Wireless Communication Systems","authors":"Norisato Suga;Kazuto Yano;Yafei Hou;Toshikazu Sakano","doi":"10.23919/comex.2024XBL0058","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0058","url":null,"abstract":"Intelligent reflecting surface (IRS), which can reflect radio waves controlling the phase of incident radio waves, is being investigated for wireless communication in high-frequency bands. To control the reflection characteristic, it is necessary to separately estimate a large number of channel coefficients between transmitting and receiving antennas through each IRS element. This causes significant overhead for the channel estimation. We have proposed a channel prediction method to reduce the overhead using Gaussian process regression with spectral mixture kernel. In Gaussian process regression, the determination of the hyperparameters used to calculate the kernel matrix has a significant impact on prediction accuracy. In this study, we propose validation-based hyperparameter determination for GPR-based channel prediction and evaluate the performance difference between the gradient method and validation.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"315-318"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554672","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973496","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One possible approach to address communication delay in the complex wireless environment of manufacturing sites is to predict the delay by system-level simulator (SLS) and notify the communication control system in advance. For accurate delay prediction, the carrier sense (CS) model in SLS should incorporate real device characteristics. However, accurate modeling of CS is difficult since its implementation specifications are usually not publicly available. In this letter, we propose a method for estimating CS characteristics using electromagnetic noise generated simulatively by software-defined radio and emitted from a microwave oven and verify the effectiveness of this method.
{"title":"Measurement-Based Estimation of Carrier Sense Behavior for Simulation Modeling","authors":"Ayano Ohnishi;Tetsuya Iye;Michio Miyamoto;Takahito Inoshita","doi":"10.23919/comex.2024XBL0045","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0045","url":null,"abstract":"One possible approach to address communication delay in the complex wireless environment of manufacturing sites is to predict the delay by system-level simulator (SLS) and notify the communication control system in advance. For accurate delay prediction, the carrier sense (CS) model in SLS should incorporate real device characteristics. However, accurate modeling of CS is difficult since its implementation specifications are usually not publicly available. In this letter, we propose a method for estimating CS characteristics using electromagnetic noise generated simulatively by software-defined radio and emitted from a microwave oven and verify the effectiveness of this method.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"323-326"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554801","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0067
Hironao Abe;Hideo Kawata;Yuhei Kawakami;Akifumi Tanase;Shinichi Yoshihara;Tomoaki Yoshida
IEEE802.1Qbv Time-Aware Shaper (TAS) has attracted attention as a technology to realize low-delay communication in various fields. Especially in industrial networks, the demand for low-latency communication between remote areas is increasing, and the realization of a service provider network (SPNW) using TAS is expected. We consider the scheduling scheme of TAS for SPNW. When the scheduling order cannot be controlled, as in SPNW, the bandwidth utilization efficiency is lower than when the scheduling order is ideal. To cope with such problems, we propose a rescheduling scheme focusing on the difference in scheduling difficulty. However, the increase in computational load due to rescheduling has not been discussed. In this paper, we consider a method to reduce the computation time of the rescheduling method.
IEEE802.1Qbv 时间感知整形器（TAS）作为一种实现低延迟通信的技术，在各个领域都备受关注。特别是在工业网络中，偏远地区之间对低延迟通信的需求日益增长，利用 TAS 实现服务提供商网络（SPNW）成为人们的期待。我们考虑了 SPNW 的 TAS 调度方案。在 SPNW 中，当调度顺序无法控制时，带宽利用效率会比调度顺序理想时低。为应对此类问题，我们提出了一种以调度难度差异为重点的重新调度方案。然而，由于重新调度而增加的计算负荷尚未得到讨论。在本文中，我们考虑了一种减少重新调度方法计算时间的方法。
{"title":"Proposal to Reduce Computation Time in TAS Rescheduling Scheme","authors":"Hironao Abe;Hideo Kawata;Yuhei Kawakami;Akifumi Tanase;Shinichi Yoshihara;Tomoaki Yoshida","doi":"10.23919/comex.2024XBL0067","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0067","url":null,"abstract":"IEEE802.1Qbv Time-Aware Shaper (TAS) has attracted attention as a technology to realize low-delay communication in various fields. Especially in industrial networks, the demand for low-latency communication between remote areas is increasing, and the realization of a service provider network (SPNW) using TAS is expected. We consider the scheduling scheme of TAS for SPNW. When the scheduling order cannot be controlled, as in SPNW, the bandwidth utilization efficiency is lower than when the scheduling order is ideal. To cope with such problems, we propose a rescheduling scheme focusing on the difference in scheduling difficulty. However, the increase in computational load due to rescheduling has not been discussed. In this paper, we consider a method to reduce the computation time of the rescheduling method.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"343-346"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554802","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0091
Masaya Ohta;Koichi Kubota
This research uses deep learning to address the high peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM), which is critical for wireless communications. Although a PAPR-reducing network (PRNet), which is a deep learning model, can be used to suppress the PAPR, its computational cost is huge. In this research, the number of layers in a PRNet model is optimized and a fully connected layer is replaced with a convolution layer to reduce the computational load.
{"title":"PRNet with Convolution Layer for PAPR Reduction of OFDM Signals","authors":"Masaya Ohta;Koichi Kubota","doi":"10.23919/comex.2024XBL0091","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0091","url":null,"abstract":"This research uses deep learning to address the high peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM), which is critical for wireless communications. Although a PAPR-reducing network (PRNet), which is a deep learning model, can be used to suppress the PAPR, its computational cost is huge. In this research, the number of layers in a PRNet model is optimized and a fully connected layer is replaced with a convolution layer to reduce the computational load.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"339-342"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554794","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CAPTCHAs have traditionally been used to deter bots, but ensuring protection against machine learning attacks has become difficult. To tackle this problem, we proposed a CAPTCHA based on color constancy, a human cognitive ability that is difficult for machines to reproduce. Although this method achieved high attack resistance while maintaining usability compared to existing CAPTCHAs, the response time increased due to the color selection operation. To address this, we changed the task to a click-type format while keeping the original concept. Our experimental results show that our method matches the response times of existing CAPTCHAs without compromising attack resistance.
{"title":"Usability Improvement in Color Constancy CAPTCHA","authors":"Shotaro Usuzaki;Wang Yihan;Kentaro Aburada;Hisaaki Yamaba;Kayoko Takatsuka;Tetsuro Katayama;Mirang Park;Naonobu Okazaki","doi":"10.23919/comex.2024XBL0052","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0052","url":null,"abstract":"CAPTCHAs have traditionally been used to deter bots, but ensuring protection against machine learning attacks has become difficult. To tackle this problem, we proposed a CAPTCHA based on color constancy, a human cognitive ability that is difficult for machines to reproduce. Although this method achieved high attack resistance while maintaining usability compared to existing CAPTCHAs, the response time increased due to the color selection operation. To address this, we changed the task to a click-type format while keeping the original concept. Our experimental results show that our method matches the response times of existing CAPTCHAs without compromising attack resistance.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"331-334"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554800","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973528","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0057
Iori Serizawa;Nobuhiro Kuga
This letter proposes a concept of residual noise reduction when using multiple testers for non-contact passive intermodulation (PIM) measurements with near field sensing for array antennas. As described herein, the harmonic balance method and the finite difference time domain method are used for simulation. Examination is conducted for third-order PIMs in two-tone testing in the 2 GHz band. Simulation results indicate that the PIM noise which is weaker than the residual PIM of each tester becomes detectable when using the proposed method. The concept is validated further through experimentation using an equivalent array circuit in the 2 GHz band.
{"title":"System Residual Noise Reduction for Non-Contact Passive Intermodulation Measurements of Array Antennas Using Multiple Testers","authors":"Iori Serizawa;Nobuhiro Kuga","doi":"10.23919/comex.2024XBL0057","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0057","url":null,"abstract":"This letter proposes a concept of residual noise reduction when using multiple testers for non-contact passive intermodulation (PIM) measurements with near field sensing for array antennas. As described herein, the harmonic balance method and the finite difference time domain method are used for simulation. Examination is conducted for third-order PIMs in two-tone testing in the 2 GHz band. Simulation results indicate that the PIM noise which is weaker than the residual PIM of each tester becomes detectable when using the proposed method. The concept is validated further through experimentation using an equivalent array circuit in the 2 GHz band.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"335-338"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554807","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0093
Yuji Yano;Hisashi Iwamoto;Tsutomu Sasao;Shingo Ata
As a result of the growth of autonomous driving technology, vehicle networks increasingly require not only broadband capabilities and real-time communication, but also enhanced security features. In this paper, we propose a lightweight security switch using hierarchical hash table to achieve security functionality at the central gateway within the vehicle network. Our proposed switch combines header information from Layer-2 to Layer-4 to determine whether incoming packets are attack packets or not. It also achieves fast packet forwarding using low-latency hierarchical hash table. We evaluated the system performance with the FPGA board implementing the proposed security switch, and achieved low-latency transfers of 500 nanoseconds or less.
{"title":"Implementation and Evaluation of Lightweight in-Vehicle Security Switch with Hierarchical Hash Table","authors":"Yuji Yano;Hisashi Iwamoto;Tsutomu Sasao;Shingo Ata","doi":"10.23919/comex.2024XBL0093","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0093","url":null,"abstract":"As a result of the growth of autonomous driving technology, vehicle networks increasingly require not only broadband capabilities and real-time communication, but also enhanced security features. In this paper, we propose a lightweight security switch using hierarchical hash table to achieve security functionality at the central gateway within the vehicle network. Our proposed switch combines header information from Layer-2 to Layer-4 to determine whether incoming packets are attack packets or not. It also achieves fast packet forwarding using low-latency hierarchical hash table. We evaluated the system performance with the FPGA board implementing the proposed security switch, and achieved low-latency transfers of 500 nanoseconds or less.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"347-350"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554805","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0085
Akari Yoshimura;Yoshihiro Ito
This paper evaluates the QoS of Ethernet-based in-vehicle networks with Asynchronous Traffic Shaping (ATS), Credit-Based Shaper (CBS), and Traffic Aware Shaper (TAS), which are QoS controls defined in IEEE 802.1TSN(Time Sensitive Networking), by experiment; it then compares QoS among them. Since the number of ECUs is increasing and moving toward the realization of fully automated vehicles, Ethernet is being introduced to send them. In addition, as Ethernet-based in-vehicle networks are being deployed, adopting IEEE 802.1TSN is also being considered. Although many studies have evaluated QoS controls, such as CBS and TAS, few studies of QoS provided ATS over in-vehicle networks. Thus, the authors evaluate the QoS of ATS and then compare ATS to the other QoS controls by two experiments. One evaluates basic QoS, and the other treats actual use cases. Experimental results show that ATS can suppress maximum delay and frame losses more than the other controls when the frame interval is wide and the size is large over in-vehicle network. Moreover, they also indicate that ATS can reduce the maximum delay and delay jitter at the sacrifice of the frame loss rate by lowering the maximum residence time. Therefore, if the requirement for delay is more important than that for frame losses. it is better to adopt ATS.
{"title":"QoS Evaluation of ATS in IEEE 802.1TSN on In-Vehicle Ethernet by Comparing with CBS and TAS","authors":"Akari Yoshimura;Yoshihiro Ito","doi":"10.23919/comex.2024XBL0085","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0085","url":null,"abstract":"This paper evaluates the QoS of Ethernet-based in-vehicle networks with Asynchronous Traffic Shaping (ATS), Credit-Based Shaper (CBS), and Traffic Aware Shaper (TAS), which are QoS controls defined in IEEE 802.1TSN(Time Sensitive Networking), by experiment; it then compares QoS among them. Since the number of ECUs is increasing and moving toward the realization of fully automated vehicles, Ethernet is being introduced to send them. In addition, as Ethernet-based in-vehicle networks are being deployed, adopting IEEE 802.1TSN is also being considered. Although many studies have evaluated QoS controls, such as CBS and TAS, few studies of QoS provided ATS over in-vehicle networks. Thus, the authors evaluate the QoS of ATS and then compare ATS to the other QoS controls by two experiments. One evaluates basic QoS, and the other treats actual use cases. Experimental results show that ATS can suppress maximum delay and frame losses more than the other controls when the frame interval is wide and the size is large over in-vehicle network. Moreover, they also indicate that ATS can reduce the maximum delay and delay jitter at the sacrifice of the frame loss rate by lowering the maximum residence time. Therefore, if the requirement for delay is more important than that for frame losses. it is better to adopt ATS.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 9","pages":"355-358"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554799","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142090808","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-11DOI: 10.23919/comex.2024XBL0084
Linh T. Hoang;Chuyen T. Nguyen;Hoang D. Le;Anh T. Pham
Aerial base stations (ABSs) have been envisioned as a promising technology toward ubiquitous coverage and seamless high-rate connectivity in sixth-generation (6G) wireless networks. With the inherent mobility but limited communication range, the placement of ABSs should adapt to the time-varying network conditions, e.g., the user distribution and wireless channel state. This letter investigates the cooperative trajectory of UAVs in an integrated terrestrial and non-terrestrial network (TNTN), where unmanned aerial vehicles (UAVs) are deployed as ABSs to supplement the terrestrial macro base station (mBS). We formulate an optimization problem to maximize the number of users with a certain minimum data rate, which is solved using multi-agent reinforcement learning (MARL). Numerical results show that the proposed design is superior to conventional approaches for the cooperative trajectory of UAVs, including K-means clustering-based and single-agent reinforcement learning (SARL)-based methods.
{"title":"Multi-Agent Reinforcement Learning for Cooperative Trajectory Design of UAV-BS Fleets in Terrestrial/Non-Terrestrial Integrated Networks","authors":"Linh T. Hoang;Chuyen T. Nguyen;Hoang D. Le;Anh T. Pham","doi":"10.23919/comex.2024XBL0084","DOIUrl":"https://doi.org/10.23919/comex.2024XBL0084","url":null,"abstract":"Aerial base stations (ABSs) have been envisioned as a promising technology toward ubiquitous coverage and seamless high-rate connectivity in sixth-generation (6G) wireless networks. With the inherent mobility but limited communication range, the placement of ABSs should adapt to the time-varying network conditions, e.g., the user distribution and wireless channel state. This letter investigates the cooperative trajectory of UAVs in an integrated terrestrial and non-terrestrial network (TNTN), where unmanned aerial vehicles (UAVs) are deployed as ABSs to supplement the terrestrial macro base station (mBS). We formulate an optimization problem to maximize the number of users with a certain minimum data rate, which is solved using multi-agent reinforcement learning (MARL). Numerical results show that the proposed design is superior to conventional approaches for the cooperative trajectory of UAVs, including K-means clustering-based and single-agent reinforcement learning (SARL)-based methods.","PeriodicalId":54101,"journal":{"name":"IEICE Communications Express","volume":"13 8","pages":"327-330"},"PeriodicalIF":0.3,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10554673","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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