Several factors influence listening comprehension of English radio news broadcasts. The study adopted a questionnaire to investigate students' recognition of these factors. On the basis of this analysis, students ...Several factors influence listening comprehension of English radio news broadcasts. The study adopted a questionnaire to investigate students' recognition of these factors. On the basis of this analysis, students put emphasis on vocabulary and background knowledge and they were aware of the approaches to better listening comprehension and making some practical preparations before doing the listening tasks. However some differences exist between the effective listeners and less-effective listeners,specially regarding to speech rate and out-of-class relevant practice.展开更多
INTRODUCTION As English teachers, we have devoted a lot of time to the teaching of listening comprehension using radio broadcasts. We began by using VOA news in special English with freshmen and a mixture of news in s...INTRODUCTION As English teachers, we have devoted a lot of time to the teaching of listening comprehension using radio broadcasts. We began by using VOA news in special English with freshmen and a mixture of news in special English and standard news broadcasts with sophomores. Later BBC news was used. We accumulated a considerable amount of experience and did some research into the design of listening comprehension exercises. This article discusses how listening ability may be improved by using such broadcasts.展开更多
While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a sh...While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.展开更多
Deep learning-based Joint Source-Channel Coding(JSCC)is a crucial component in semantic communication,and recent research has made significant progress in adapting to different channels.In this paper,we propose a mult...Deep learning-based Joint Source-Channel Coding(JSCC)is a crucial component in semantic communication,and recent research has made significant progress in adapting to different channels.In this paper,we propose a multi-stage progressive technique called Deep learning based Progressive Joint Source-Channel Coding(DP-JSCC).This approach partitions the source into multiple stages and transmits the signals continuously.The receiver gradually enhances the quality of image reconstruction by progressively receiving the signals,offering greater flexibility compared to existing dynamic rate transmission methods.The model adopts a lightweight architectural design,where we introduce an efficient module called the Inverted Shuffle Attention Bottleneck(ISAB)and incorporate self-attention mechanisms in the encoding and decoding process to capture signal correlations and establish long-range dependencies.Additionally,we introduce the Progressive Focus Weight Allocation(PFWA)method to improve the image reconstruction capability in progressive transmission tasks.These design enhance the expressive capacity of the model.Simulation results demonstrate that DP-JSCC can flexibly adjust the transmission rate according to requirements without the need for retraining or deployment,enabling continuous optimization of signals at different rates.Furthermore,compared to stateof-the-art JSCC methods,DP-JSCC exhibits advantages in terms of computational complexity,parameter count,and reconstruction performance.展开更多
Reconfigurable intelligent surface(RIS)has proven to be promising for future wireless communication.Due to its ability to manipulate electromagnetic(EM)waves,RIS provides a flexible and programmable way to implement i...Reconfigurable intelligent surface(RIS)has proven to be promising for future wireless communication.Due to its ability to manipulate electromagnetic(EM)waves,RIS provides a flexible and programmable way to implement intelligent wireless environments.While path loss modeling has been conducted in some prior research,an issue remaining unknown is the characteristics of multi-beam path loss for RIS.In this paper,we model,simulate and measure the multi-beam path loss in RIS-assisted broadcast communication scenarios.We propose two specific configurations of RIS and derive the path loss models,which reveal that the incident beam can be equally divided into multiple beams without power loss through rational design of the phase coding.The proposed path loss model is validated through simulation subsequently.To further verify our conclusions,we build a millimeter wave(mmWave)measurement system with a 35 GHz fabricated RIS.The measurement result corresponds well with the simulation,which shows a difference of about 3 dB in the received signal power of quad-beam compared with dual-beam,as well as dual-beam compared with single-beam,except for the impact of radiation patterns of the antennas and RIS elements.展开更多
1.Introduction It has been almost 60 years since the launch of Intelsat-I,the world’s first commercial satellite communications system.Over the past few decades,the development of satellite communications has been dr...1.Introduction It has been almost 60 years since the launch of Intelsat-I,the world’s first commercial satellite communications system.Over the past few decades,the development of satellite communications has been driven by both technological advancements and growing application demands,which have given rise to three primary services:broadcast,fixed satellite,and mobile satellite services[1].展开更多
Unmanned Aerial Vehicle(UAV)-aided communication,prized for its network reconfigurability,operational flexibility,and cost-effectiveness,is a key enabler of the low-altitude economy.However,the high possibilities of l...Unmanned Aerial Vehicle(UAV)-aided communication,prized for its network reconfigurability,operational flexibility,and cost-effectiveness,is a key enabler of the low-altitude economy.However,the high possibilities of line-of-sight links and the broadcast nature of air-ground UAV communications make it vulnerable and prone to eavesdropping by malicious nodes.展开更多
Unmanned Aerial Vehicle(UAV)-aided communication holds great potential to enhance the transmission performance.However,the information security remains a fundamental requirement due to the high possibilities of line-o...Unmanned Aerial Vehicle(UAV)-aided communication holds great potential to enhance the transmission performance.However,the information security remains a fundamental requirement due to the high possibilities of line-of-sight links and the broadcast nature.展开更多
Passive bistatic radar(PBR)frequently experiences interference from direct signal waves when detecting maritime targets,which can completely mask target echoes,particularly for distant targets or weak targets with low...Passive bistatic radar(PBR)frequently experiences interference from direct signal waves when detecting maritime targets,which can completely mask target echoes,particularly for distant targets or weak targets with low radar cross-section(RCS).To mitigate this,the paper proposes a direct signal interference(DSI)suppression method.The approach involves dual-channel reception of digital video broadcast satellites(DVB-S)signals from the China Sat-9,followed by signal pre-processing.The reference and surveillance channel signals are then segmented.After segmentation,the signals undergo fast Fourier transformation(FFT),and an adaptive filtering clutter suppres-sion method is applied at each frequency point.Finally,an inverse fast Fourier transform(IFFT)is performed on the suppressed signals to obtain the DSI-suppressed output.Compared to traditional clutter suppression techniques,this method is not only faster but also achieves more effective sup-pression.Simulation experiments involving both single and multiple targets validate the superiority of the proposed algorithm.展开更多
Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcas...Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.展开更多
In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. ...In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.展开更多
2014年7月28日美国国会众议院通过《美国国际广播改革法案》（U.S. International Broadcasting Reform Bill,H.R.4490）,标志着美国国内针对美国广播理事会（Broadcasting Board of Governors,BBG）的改革拉开了序幕。近些年,美国国内...2014年7月28日美国国会众议院通过《美国国际广播改革法案》（U.S. International Broadcasting Reform Bill,H.R.4490）,标志着美国国内针对美国广播理事会（Broadcasting Board of Governors,BBG）的改革拉开了序幕。近些年,美国国内对BBG进行改革的呼声日益强烈,其主要原因是美国国际广播的传播影响力受到质疑。展开更多
This paper presented a new shared cache technique-the grouping cache, which could solve many invalid queries in the broadcast probe and the control bottleneck of the centralized web cache by dividing all cooperative c...This paper presented a new shared cache technique-the grouping cache, which could solve many invalid queries in the broadcast probe and the control bottleneck of the centralized web cache by dividing all cooperative caches into several groups according to their positions in the network topology. The technique has the following characteristics: The overhead of multi-cache query can be reduced efficiently by the cache grouping scheme; the compact summary of the cache directory can rapidly determine if a request exists in a cache within the group; the distribution algorithm based on the web-access logs can effectively balance the load among all the groups. The simulation test demonstrated that the grouping cache was more effective than any other existing shared cache techniques.展开更多
The medium access control (MAC) issue was discussed in mobile Ad Hoc networks (MANETs). Based on the IEEE 802.11 MAC protocol, this paper proposed two schemes, the forward-packet-first (FPF) scheme based on the adapti...The medium access control (MAC) issue was discussed in mobile Ad Hoc networks (MANETs). Based on the IEEE 802.11 MAC protocol, this paper proposed two schemes, the forward-packet-first (FPF) scheme based on the adaptive backoff contention window and multihop forward chain transmission by invitation (MFCTI) scheme. In the FPF scheme, the contention window was adjusted adaptively according to the traffic priority. Route information and the broadcast characteristic of radio were utilized in MFCTI scheme. The performance of these schemes was studied in multihop environments by simulations. The results showed that the proposed schemes could improve the network throughput, reduce the end-to-end average delay, and mitigate local congestion effectively. Another attractive feature was that the schemes could be implemented with minor modifications to the IEEE 802.11 MAC.展开更多
An improved internetworking approach is proposed to enhance the Internet connectivity which is deteriorated due to unidirectional links and blind rebroadcasting of gateway discovery packets for mobile ad hoc networks....An improved internetworking approach is proposed to enhance the Internet connectivity which is deteriorated due to unidirectional links and blind rebroadcasting of gateway discovery packets for mobile ad hoc networks. The hybrid gateway discovery scheme that combined the advantages of a proactive and reactive gateway discovery approach is used to achieve high connectivity while keeping overhead costs low. By exchanging ad hoc on-demand distance vector （AODV） hello packet which includes additional fields named symmetric neighbor list and asymmetric neighbor list, unidirectional links are removed from route computation and broadcast storm can also be relieved simultaneously. Performance results using ns-2 simulations, under varying numbers of unidirectional links and node speeds, show that this improved Internet connectivity approach can provide better performance than others.展开更多
文摘Several factors influence listening comprehension of English radio news broadcasts. The study adopted a questionnaire to investigate students' recognition of these factors. On the basis of this analysis, students put emphasis on vocabulary and background knowledge and they were aware of the approaches to better listening comprehension and making some practical preparations before doing the listening tasks. However some differences exist between the effective listeners and less-effective listeners,specially regarding to speech rate and out-of-class relevant practice.
文摘INTRODUCTION As English teachers, we have devoted a lot of time to the teaching of listening comprehension using radio broadcasts. We began by using VOA news in special English with freshmen and a mixture of news in special English and standard news broadcasts with sophomores. Later BBC news was used. We accumulated a considerable amount of experience and did some research into the design of listening comprehension exercises. This article discusses how listening ability may be improved by using such broadcasts.
文摘While feeding her ostriches,Wang Xue swiftly responds to fans'questions with a sense of humor through her popular live‑streaming channel.Since Wang,30,an expert in ostrich farming,started live broadcasting on a short‑video platform with her husband Han Peng,their ostrich farming business has flourished,garnering nearly 3 million fans on the platform.“The highest viewership for one single live broadcast reached over 6 million,”said Wang,adding that riding an ostrich at high speed was an essential part of her broadcasts.Through her videos,Wang brought fans close to the ostriches,providing details of their habits,farming methods and economic value.
文摘Deep learning-based Joint Source-Channel Coding(JSCC)is a crucial component in semantic communication,and recent research has made significant progress in adapting to different channels.In this paper,we propose a multi-stage progressive technique called Deep learning based Progressive Joint Source-Channel Coding(DP-JSCC).This approach partitions the source into multiple stages and transmits the signals continuously.The receiver gradually enhances the quality of image reconstruction by progressively receiving the signals,offering greater flexibility compared to existing dynamic rate transmission methods.The model adopts a lightweight architectural design,where we introduce an efficient module called the Inverted Shuffle Attention Bottleneck(ISAB)and incorporate self-attention mechanisms in the encoding and decoding process to capture signal correlations and establish long-range dependencies.Additionally,we introduce the Progressive Focus Weight Allocation(PFWA)method to improve the image reconstruction capability in progressive transmission tasks.These design enhance the expressive capacity of the model.Simulation results demonstrate that DP-JSCC can flexibly adjust the transmission rate according to requirements without the need for retraining or deployment,enabling continuous optimization of signals at different rates.Furthermore,compared to stateof-the-art JSCC methods,DP-JSCC exhibits advantages in terms of computational complexity,parameter count,and reconstruction performance.
基金supported in part by the National Key Research and Development Program of China under Grants 2023YFB3811505in part by the National Natural Science Foundation of China(NSFC)under Grants 62261160576,62201138,62301156,and 62401137+4 种基金in part by the Key Technologies R&D Program of Jiangsu(Prospective and Key Technologies for Industry)under Grants BE2023022-1 and BE2023022in part by the Natural Science Foundation of Jiangsu Province under Grant BK20220809 and BK20241281in part by the Fundamental Research Funds for the Central Universities under Grant 2242023K5003in part by the China National Postdoctoral Program for Innovative Talents under Grant BX20230065in part by the Jiangsu Excellent Postdoctoral Program under Grant 2023ZB476.
文摘Reconfigurable intelligent surface(RIS)has proven to be promising for future wireless communication.Due to its ability to manipulate electromagnetic(EM)waves,RIS provides a flexible and programmable way to implement intelligent wireless environments.While path loss modeling has been conducted in some prior research,an issue remaining unknown is the characteristics of multi-beam path loss for RIS.In this paper,we model,simulate and measure the multi-beam path loss in RIS-assisted broadcast communication scenarios.We propose two specific configurations of RIS and derive the path loss models,which reveal that the incident beam can be equally divided into multiple beams without power loss through rational design of the phase coding.The proposed path loss model is validated through simulation subsequently.To further verify our conclusions,we build a millimeter wave(mmWave)measurement system with a 35 GHz fabricated RIS.The measurement result corresponds well with the simulation,which shows a difference of about 3 dB in the received signal power of quad-beam compared with dual-beam,as well as dual-beam compared with single-beam,except for the impact of radiation patterns of the antennas and RIS elements.
基金supported in part by the National Key Research and Development Program of China(2023YFB2904703).
文摘1.Introduction It has been almost 60 years since the launch of Intelsat-I,the world’s first commercial satellite communications system.Over the past few decades,the development of satellite communications has been driven by both technological advancements and growing application demands,which have given rise to three primary services:broadcast,fixed satellite,and mobile satellite services[1].
文摘Unmanned Aerial Vehicle(UAV)-aided communication,prized for its network reconfigurability,operational flexibility,and cost-effectiveness,is a key enabler of the low-altitude economy.However,the high possibilities of line-of-sight links and the broadcast nature of air-ground UAV communications make it vulnerable and prone to eavesdropping by malicious nodes.
文摘Unmanned Aerial Vehicle(UAV)-aided communication holds great potential to enhance the transmission performance.However,the information security remains a fundamental requirement due to the high possibilities of line-of-sight links and the broadcast nature.
基金supported in part by Shanghai Sailing Scholar(No.23YF1412700)in part by the Key Laboratory Innova-tion and Development Fund Project,China(No.61424132006).
文摘Passive bistatic radar(PBR)frequently experiences interference from direct signal waves when detecting maritime targets,which can completely mask target echoes,particularly for distant targets or weak targets with low radar cross-section(RCS).To mitigate this,the paper proposes a direct signal interference(DSI)suppression method.The approach involves dual-channel reception of digital video broadcast satellites(DVB-S)signals from the China Sat-9,followed by signal pre-processing.The reference and surveillance channel signals are then segmented.After segmentation,the signals undergo fast Fourier transformation(FFT),and an adaptive filtering clutter suppres-sion method is applied at each frequency point.Finally,an inverse fast Fourier transform(IFFT)is performed on the suppressed signals to obtain the DSI-suppressed output.Compared to traditional clutter suppression techniques,this method is not only faster but also achieves more effective sup-pression.Simulation experiments involving both single and multiple targets validate the superiority of the proposed algorithm.
文摘Beginning with the simple introduction of socket which is the most commonly used application program interfaces in UNIX/LINUX communication domain, the concrete programming procedures to realize multicast and broadcast based on socket is provided, according to TCP/IP protocol in LINUX system. The acquiring and converting of broadcast destination address and multicast address, the setting of multicast options, the joining in and withdrawing from the multicast group, and the receiving and sending of datagram are all demonstrated in it, the related system calls and simple explication of C programming are also included.
基金The National High Technology Research and Development Program of China (863 Program) (No.2008AA01Z227)the Cultivatable Fund of the Key Scientific and Technical Innovation Project of Ministry of Education of China (No.706028)
文摘In order to enhance the accuracy and reliability of wireless location under non-line-of-sight （NLOS） environments,a novel neural network （NN） location approach using the digital broadcasting signals is presented. By the learning ability of the NN and the closely approximate unknown function to any degree of desired accuracy,the input-output mapping relationship between coordinates and the measurement data of time of arrival （TOA） and time difference of arrival （TDOA） is established. A real-time learning algorithm based on the extended Kalman filter （EKF） is used to train the multilayer perceptron （MLP） network by treating the linkweights of a network as the states of the nonlinear dynamic system. Since the EKF-based learning algorithm approximately gives the minimum variance estimate of the linkweights,the convergence is improved in comparison with the backwards error propagation （BP） algorithm. Numerical results illustrate thatthe proposedalgorithmcanachieve enhanced accuracy,and the performance ofthe algorithmis betterthanthat of the BP-based NN algorithm and the least squares （LS） algorithm in the NLOS environments. Moreover,this location method does not depend on a particular distribution of the NLOS error and does not need line-of-sight （ LOS ） or NLOS identification.
文摘2014年7月28日美国国会众议院通过《美国国际广播改革法案》（U.S. International Broadcasting Reform Bill,H.R.4490）,标志着美国国内针对美国广播理事会（Broadcasting Board of Governors,BBG）的改革拉开了序幕。近些年,美国国内对BBG进行改革的呼声日益强烈,其主要原因是美国国际广播的传播影响力受到质疑。
文摘This paper presented a new shared cache technique-the grouping cache, which could solve many invalid queries in the broadcast probe and the control bottleneck of the centralized web cache by dividing all cooperative caches into several groups according to their positions in the network topology. The technique has the following characteristics: The overhead of multi-cache query can be reduced efficiently by the cache grouping scheme; the compact summary of the cache directory can rapidly determine if a request exists in a cache within the group; the distribution algorithm based on the web-access logs can effectively balance the load among all the groups. The simulation test demonstrated that the grouping cache was more effective than any other existing shared cache techniques.
文摘The medium access control (MAC) issue was discussed in mobile Ad Hoc networks (MANETs). Based on the IEEE 802.11 MAC protocol, this paper proposed two schemes, the forward-packet-first (FPF) scheme based on the adaptive backoff contention window and multihop forward chain transmission by invitation (MFCTI) scheme. In the FPF scheme, the contention window was adjusted adaptively according to the traffic priority. Route information and the broadcast characteristic of radio were utilized in MFCTI scheme. The performance of these schemes was studied in multihop environments by simulations. The results showed that the proposed schemes could improve the network throughput, reduce the end-to-end average delay, and mitigate local congestion effectively. Another attractive feature was that the schemes could be implemented with minor modifications to the IEEE 802.11 MAC.
基金The National Natural Science Foundation of China(No60362001)
文摘An improved internetworking approach is proposed to enhance the Internet connectivity which is deteriorated due to unidirectional links and blind rebroadcasting of gateway discovery packets for mobile ad hoc networks. The hybrid gateway discovery scheme that combined the advantages of a proactive and reactive gateway discovery approach is used to achieve high connectivity while keeping overhead costs low. By exchanging ad hoc on-demand distance vector （AODV） hello packet which includes additional fields named symmetric neighbor list and asymmetric neighbor list, unidirectional links are removed from route computation and broadcast storm can also be relieved simultaneously. Performance results using ns-2 simulations, under varying numbers of unidirectional links and node speeds, show that this improved Internet connectivity approach can provide better performance than others.
