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Joint UAV trajectory and communication design with heterogeneous multi-agent reinforcement learning

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Science China(Information Sciences) 2024年第3期67卷 225-245页

作者： Xuanhan ZHOU Jun XIONG Haitao ZHAO Xiaoran LIU Baoquan REN Xiaochen ZHANG jibo wei Hao YIN College of Electronic Science and Technology National University of Defense Technology Systems Engineering Institute Academy of Military Sciences PLA

Unmanned aerial vehicles(UAVs) are recognized as effective means for delivering emergency communication services when terrestrial infrastructures are unavailable. This paper investigates a multiUAV-assisted communication system, where we jointly optimize UAVs’ trajectories, user association, and ground users(GUs)’ transmit power to maximize a defined fairness-weighted throughput metric. Owing to the dynamic nature of UAVs, this problem has to be solved in real time. However, the problem’s non-convex and combinatorial attributes pose challenges for conventional optimization-based algorithms, particularly in scenarios without central controllers. To address this issue, we propose a multi-agent deep reinforcement learning(MADRL) approach to provide distributed and online solutions. In contrast to previous MADRLbased methods considering only UAV agents, we model UAVs and GUs as heterogeneous agents sharing a common objective. Specifically, UAVs are tasked with optimizing their trajectories, while GUs are responsible for selecting a UAV for association and determining a transmit power level. To learn policies for these heterogeneous agents, we design a heterogeneous coordinated QMIX(HC-QMIX) algorithm to train local Q-networks in a centralized manner. With these well-trained local Q-networks, UAVs and GUs can make individual decisions based on their local observations. Extensive simulation results demonstrate that the proposed algorithm outperforms state-of-the-art benchmarks in terms of total throughput and system fairness.

关键词： unmanned aerial vehicle (UAV) trajectory design resource allocation multi-agent deep reinforcement learning (MADRL) heterogeneous agents

Extended context-based semantic communication system for text transmission

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Digital Communications and Networks 2024年第3期10卷 568-576页

作者： Yueling Liu Shengteng Jiang Yichi Zhang Kuo Cao Li Zhou Boon-Chong Seet Haitao Zhao jibo wei College of Electronic Science and Technology National University of Defense TechnologyChangsha410073China Department of Electrical and Electronic Engineering Auckland University of TechnologyAucklandNew Zealand

Context information is significant for semantic extraction and recovery of messages in semantic ***,context information is not fully utilized in the existing semantic communication systems since re-lationships between sentences are often *** this paper,we propose an Extended Context-based Semantic Communication(ECSC)system for text transmission,in which context information within and between sentences is explored for semantic representation and *** the encoder,self-attention and segment-level relative attention are used to extract context information within and between sentences,*** addition,a gate mechanism is adopted at the encoder to incorporate the context information from different *** the decoder,Transformer-XL is introduced to obtain more semantic information from the historical communication processes for semantic *** results show the effectiveness of our proposed model in improving the semantic accuracy between transmitted and recovered messages under various channel conditions.

关键词： semantic communication extended context Transformer-XL

Joint Network and Fountain Codes Design for RelayAssisted Multi-User System

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China Communications 2015年第7期12卷 96-107页

作者： HUANG Ying LEI Jing wei jibo Institute of Electronic Science and Engineering National University of Defense Technology

In relay-assisted multi-user system, relay coding is important to enhance the robustness and reliability of cooperative transmission. For better adaptability and efficiency, two joint network and fountain coding(JNFC) schemes are proposed. When the condition of all direct channels is worse, JNFC scheme based on distributed LT(DLT) codes is used. Otherwise, JNFC scheme based on multi-dimensional LT(MD-LT) codes is suited. For both two above-mentioned schemes, the united degree distribution design method for short-length fountain codes is proposed. For the latter scheme, MD-LT codes are proposed for equal error protection(EEP) of each user. Simulation results and analysis show that the united degree distribution need less decoding overhead compared with other degree distribution for short-length fountain codes. And then, all users are protected equally in despite of asymmetric uplinks.

关键词： relay coding network coding fountain codes LT codes Raptor codes DLT MD-LT EEP

A Joint Feedback Bit and Power Allocation Strategy for Multi-cell Systems over Composite Fading Channels

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Chinese Journal of Electronics 2016年第3期25卷 541-550页

作者： MA Yue WANG Xin WANG Haihong GE Songhu wei jibo School of Electronic Science and Engineering National University of Defense Technology

This paper addresses the joint Feedback bit allocation(FBA) and Power allocation(PA)problem for a limited feedback coordinated multi-cell transmission system over composite fading channels. The Rayleigh/Lognormal fading channel is considered, and the effects of path loss and the macro-level correlation are also taken into account. A modified performance measure, referred to as the virtual sum rate is adopted to facilitate the analysis. The closed forms of the lower bound on virtual sum rate are derived over uncorrelated and correlated shadowed fading channels. Based on the lower bound, we then formulate an optimization problem of maximizing the virtual sum rate under constraints on the total number of feedback bits per MS and the total transmit power per BS. Considering the tight coupling between the FBA and the PA, we solve the optimization problem by solving an alternating sequence of FBA and PA subproblems using a coordinated ascent searching method. Numerical results show that the proposed strategy can converge in a few iterations and generally yield better performance than the conventional FBA schemes under composite fading channels.

关键词： Rayleigh/Lognormal fading Feedback bit allocation(FBA) Power allocation(PA) Limited feedback Multi-cell

AN IMPROVED MARKOV CHAIN MONTE CARLO METHOD FOR MIMO ITERATIVE DETECTION AND DECODING

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Journal of Electronics(China) 2008年第3期25卷 305-310页

作者： Han Xiang wei jibo Dept of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China

Recently, a new soft-in soft-out detection algorithm based on the Markov Chain Monte Carlo (MCMC) simulation technique for Multiple-Input Multiple-Output (MIMO) systems is proposed, which is shown to perform significantly better than their sphere decoding counterparts with relatively low complexity. However, the MCMC simulator is likely to get trapped in a fixed state when the channel SNR is high, thus lots of repetitive samples are observed and the accuracy of A Posteriori Probability (APP) estimation deteriorates. To solve this problem, an improved version of MCMC simulator, named forced-dispersed MCMC algorithm is proposed. Based on the a posteriori variance of each bit, the Gibbs sampler is monitored. Once the trapped state is detected, the sample is dispersed intentionally according to the a posteriori variance. Extensive simulation shows that, compared with the existing solution, the proposed algorithm enables the markov chain to travel more states, which ensures a near-optimal performance.

关键词： List Sphere Decoding (LSD) Gibbs sampler Markov Chain Monte Carlo (MCMC)

基于DRL的定向网络时隙复用和功率控制协议

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信号处理 2024年第7期40卷 1341-1353页

作者：梁仕杰赵海涛张姣王海军魏急波王俊芳中国电子科技集团公司第五十四研究所河北石家庄050081 国防科技大学电子科学学院湖南长沙410073

近年来,无人机网络逐渐地广泛应用于各行各业,对无人机网络能提供的网络容量提出了更高的要求。定向天线结合无人机网络构成定向无人机网络以增加网络资源应对无人机网络中各个节点对网络有限通信资源的竞争造成网络容量低的问题。定向... 详细信息

近年来,无人机网络逐渐地广泛应用于各行各业,对无人机网络能提供的网络容量提出了更高的要求。定向天线结合无人机网络构成定向无人机网络以增加网络资源应对无人机网络中各个节点对网络有限通信资源的竞争造成网络容量低的问题。定向无人机网络通过定向天线的空间复用能力可以提高网络的时隙利用效率。针对TDMA协议在定向组网中时隙利用率过低导致网络容量受限的问题,该文提出了一种基于深度Q网络(DQN)的定向无人机网络时隙复用和功率控制协议。为了提高时隙利用率,考虑在单位时隙进行多个链路通信以实现时隙资源的复用。然而多个链路在同一个时隙通信会产生链路间的干扰,如何在考虑链路间相互干扰的情况下控制功率提高网络的容量是时隙复用研究的重点问题。为了解决该问题,首先考虑以功率要求和每条链路最小信道容量为约束,考虑相较于其他研究更为复杂更符合实际的链路互干扰模型,建模问题为最大全网容量问题。然后为了构建链路间的更复杂的互干扰环境,将多个链路的瞬时信道信息、定向增益状态融入到DQN框架的状态中,DQN的奖励为高于最小信道容量的链路信道容量的和。最后,将每个时隙的优化问题扩展到每一帧的优化问题,并利用多个DQN进行求解。仿真结果表明,在保证每个被分配时隙的最小信道容量前提下,相较于对比方法网络容量有了很大的提升。

关键词：时分多址协议定向无人机网络深度Q网络时隙复用功率控制

Multiple symbol differential detection based on sphere decoding for unitary space-time modulation

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Science in China(Series F) 2009年第1期52卷 126-137页

作者： LI Ying wei jibo WANG Xin YU Quan School of Electronic Science and Engineering National University of Defense Technology Changsha 410073 China China Electronic System Engineering Company Beijing 100039 China

Recently, a multiple symbol differential （MSD） sphere decoding （SD） algorithm for unitary spacetime modulation over quasi-static channel has been proved to achieve the performance of maximumlikelihood （ML） detection with relatively low complexity. However, an error floor occurs if the algorithm is applied over rapid-fading channels. Based on the assumption of continuous fading, a multiple symbol differential automatic sphere decoding （MSDASD） algorithm is developed by incorporating a recursive form of an ML metric into automatic SD （ASD） algorithm. Furthermore, two algorithms, termed as MSD approximate ASD （MSDAASD） and MSD pruning ASD （MSDPASD）, are proposed to reduce computational complexity and the number of comparisons, respectively. Compared with the existing typical algorithms, i.e., multiple symbol differential feedback detection （MS-DFD） and noncoherent sequence detection （NSD）, the performance of the proposed algorithms is much superior to that of MS-DFD and a little inferior to that of NSD, while the complexity is lower than that of MS-DFD in most cases and significantly lower than that of NSD.

关键词： differential unitary space-time modulation multiple symbol differential detection (MSDD) sphere decoding (SD)

Towards Wide-Open, Adaptable DCF Implementation for Dynamic Networks

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China Communications 2012年第7期9卷 77-89页

作者： Wang Shan Abdelhakim Hafid Zhao Haitao Huang Shengchun Xieng Chunlin wei jibo College of Electronic Science and Engineering National University of Defense Technology (Shangsha 41UU/'L~P. R. China Network Research Laboratory University of Montreal Montreal H3C 3J7 Quebec Canada

Abstract： This work proposes a Field Programmable Gate Array （FPGA）-oriented architecture for the IEEE 802.11 Distributed Coordination Function （DCF） transceiver. We describe the functional blocks carrying out the Carrier Sense Multiple Accesses with Collision Avoidance （CSMA/CA）, develop the interfaces to the application layer and the physical layer, and implement it on FPGA devices by utilizing Very-high-speed-integrated-circuit Hardware Description Language （VHDL）.

关键词： wireless networks DCF adaptation capability FPGA CSM A/CA cognitive networks

不同基质和生长调节剂对3种泥炭藓萌生分枝的影响

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贵州林业科技 2024年第1期52卷 16-21,50页

作者：杨林叶红环王莲辉韦继波贵州省林业科学研究院贵州贵阳550005

为保护泥炭藓野生资源且满足市场需求,优化泥炭藓人工种植技术。本研究从不同基质(泥炭土、黄心土、腐殖土)及生长调节剂(NAA、IBA、IAA)处理下的主茎与枝茎萌生分枝的数量、分枝长度、分枝质量等生长指标探究泥炭藓、多纹泥炭藓、暖地... 详细信息

为保护泥炭藓野生资源且满足市场需求,优化泥炭藓人工种植技术。本研究从不同基质(泥炭土、黄心土、腐殖土)及生长调节剂(NAA、IBA、IAA)处理下的主茎与枝茎萌生分枝的数量、分枝长度、分枝质量等生长指标探究泥炭藓、多纹泥炭藓、暖地泥炭藓萌生分枝的情况。结果表明:处理A2B3C1下暖地泥炭藓和多纹泥炭藓分枝萌生率最高,泥炭藓和暖地泥炭藓的新分枝质量最高;处理A1B3C3下泥炭藓分枝萌生率最高;处理A2B1C2下多纹泥炭藓新分枝质量最高。不同处理下3种泥炭藓的分枝生长指标间存在显著差异,其中,以处理A2B3C1下4个分枝生长指标的生长较均衡,说明栽培基质为黄心土、IAA浓度为10 mg·kg^(-1)时对泥炭藓属植物生长有促进作用。

关键词：泥炭藓暖地泥炭藓多纹泥炭藓基质生长调节剂萌生分枝