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distributed channel access for QoS control in link adaptive wireless LANs

IEICE TRANSACTIONS ON COMMUNICATIONS 2006年第6期E89B卷 1846-1855页

作者： Shinkuma, Ryoichi Maeda, Junpei Takahashi, Tatsuro Kyoto Univ Grad Sch Informat Kyoto 6068501 Japan

In wireless local area networks (WLANs), the necessity of quality-of-service (QoS) control for uplink flows is increasing because interactive applications are becoming more popular. Fairness between flows transmitted by stations with different physical transmission rates must be ensured in QoS control for link-adaptive WLANs, which are widely used nowadays. We propose a novel distributed access scheme called QC-DCA to satisfy these requirements. QC-DCA adaptively controls the parameters of carrier sense multiple access with collision avoidance (CSMA/CA). QC-DCA has two QoS control functions: guarantee and classification. QC-DCA guarantees target throughputs and packet delays by quickly adjusting CSMA/CA parameters. In QoS classification, the difference of throughputs and packet delays between different QoS classes is maintained. These two functions allow QC-DCA to suppress the unfairness caused by differences of transmission rates in the physical layer. We evaluated the throughput and delay performances of our scheme using computer simulations. The results show the viability of our scheme.

关键词： wireless LAN IEEE802.11e QoS control distributed channel access link adaptation fairness

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distributed channel access for Control Over Known and Unknown Gilbert-Elliott channels

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IEEE TRANSACTIONS ON AUTOMATIC CONTROL 2023年第12期68卷 7405-7419页

作者： Farjam, Tahmoores Wymeersch, Henk Charalambous, Themistoklis Aalto Univ Sch Elect Engn Dept Elect Engn & Automat Espoo 02150 Finland Chalmers Univ Technol Dept Elect Engn S-41296 Gothenburg Sweden Univ Cyprus Sch Engn Dept Elect & Comp Engn CY-1678 Nicosia Cyprus

In this article, we consider the distributed channel access problem for a system consisting of multiple control subsystems that close their loop over a shared wireless network with multiple channels subject to Markovian packet dropouts. Provided that an acknowledgement/ negative-acknowledgement feedback mechanism is in place, we show that this problem can be formulated as a Markov decision process. We then transform this problem to a form that enables distributed control-aware channel access. More specifically, we show that the control objective can be minimized without requiring information exchange between subsystems as long as the channel parameters are known. The objective is attained by adopting a priority-based deterministic channel access method and the stability of the system under the resulting scheme is analyzed. Next, we consider a practical scenario in which the channel parameters are unknown and adopt a learning method based on Bayesian inference, which is compatible with distributed implementation. We propose a heuristic posterior sampling algorithm, which is shown to significantly improve performance via simulations.

关键词： Bayesian inference distributed channel access Gilbert-Elliott channel online learning wireless networked control systems (WNCSs)

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distributed channel access for Device-to-Device Communications: A Hypergraph-Based Learning Solution

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IEEE COMMUNICATIONS LETTERS 2017年第1期21卷 180-183页

作者： Sun, Youming Wu, Qihui Xu, Yuhua Zhang, Yuli Sun, Fenggang Wang, Jinlong Natl Digital Switching Syst Engn & Technol Res Ct Zhengzhou 450000 Peoples R China PLA Univ Sci & Technol Coll Commun Engn Nanjing 210000 Jiangsu Peoples R China

In this letter, we propose a learning solution for distributed channel access in device-to-device communications based on a hypergraph interference model. We first define a new interference metric for a hypergraph model, and then formulate this distributed channel access problem as a local altruistic game, which is proved to be an exact potential game admitting at least one pure strategy Nash equilibrium (PNE). A distributed learning algorithm is designed to quickly achieve the optimal PNE, which can minimize the defined networks' interference metric. Simulation results show that the proposed algorithm outperforms the existing schemes and significantly improves the spectrum efficiency.

关键词： distributed channel access device-to-device communications potential game learning algorithm hypergraph

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A distributed channel access scheme with guaranteed priority and enhanced fairness

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2007年第6期6卷 2114-2125页

作者： Jiang, Hai Wang, Ping Zhuang, Weihua Princeton Univ Dept Elect Engn Princeton NJ 08544 USA Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada

Although the IEEE 802.11e enhanced distributed channel access (EDCA) can differentiate high priority traffic such as real-time voice from low priority traffic such as delay-tolerant data, it can only provide statistical priority, and is characterized by inherent short-term unfairness. In this paper, we propose a new distributed channel access scheme through minor modifications to EDCA. Guaranteed priority is provided to real-time voice traffic over data traffic, while a certain service time and short-term fairness enhancement are provided to data traffic. We also present analytical models to calculate the percentage of time to serve voice traffic and the achieved data throughput. Both analysis and simulation demonstrate the effectiveness of our proposed scheme.

关键词： IEEE 802.11e EDCA distributed channel access quality of service priority short-term fairness

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Multi-Agent Reinforcement Learning-Based distributed channel access for Next Generation Wireless Networks

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2022年第5期40卷 1587-1599页

作者： Guo, Ziyang Chen, Zhenyu Liu, Peng Luo, Jianjun Yang, Xun Sun, Xinghua Huawei Technol Co Ltd 2012 Labs Wireless Technol Lab Shenzhen 518129 Peoples R China Sun Yat Sen Univ Sch Elect & Commun Engn Shenzhen 518107 Peoples R China

In the next generation wireless networks, more applications will emerge, covering virtual reality movies, augmented reality, holographic three-dimensional telepresence, haptic telemedicine and so on, which require the provisioning of high bandwidth efficiency and low latency services. In order to better support the aforementioned applications and services, novel distributed channel access (DCA) schemes are necessary. Therefore, we propose a new MAC protocol, QMIX-advanced Listen-Before-Talk (QLBT), based on the cutting-edge multi-agent reinforcement learning (MARL) algorithm. It employs a centralized training with decentralized execution (CTDE) framework to exploit the overall information of all agents during training, and ensure that each agent can independently infer the optimal channel access behavior based on its local observation. We enhance QMIX, a well-known MARL algorithm, by introducing an extra individual Q-value for each agent in the mixing network apart from the original total Q-value, which makes QLBT more stable. Moreover, delay to last successful transmission (D2LT) is first introduced in this work as a part of the observations of each QLBT agent, which facilitates agents to reach a cooperative policy that prioritizes the agent with the longest delay. Finally, extensive simulation experiments are provided to show that the proposed QLBT algorithm: 1) outperforms CSMA/CA and even its theoretical performance bound in various scenarios including saturated traffic, unsaturated traffic and delay-sensitive traffic;2) is robust in dynamic environment;and 3) is able to friendly coexist with "legacy" CSMA/CA stations.

关键词： Media access Protocol Protocols Throughput Neural networks Heuristic algorithms Delays Training distributed channel access multi-agent reinforcement learning QMIX listen before talk multiple access

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A Timer-Based distributed channel access Mechanism in Networked Control Systems

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS 2018年第5期65卷 652-656页

作者： Farjam, Tahmoores Charalambous, Themistoklis Wymeersch, Henk Aalto Univ Sch Elect Engn Dept Elect Engn & Automat Espoo 00076 Finland Chalmers Univ Technol Dept Elect Engn S-41296 Gothenburg Sweden

We consider a system consisting of multiple heterogeneous control subsystems sharing a common communication resource for accomplishing their control tasks. Despite the numerous advantages that such networked control systems (NCSs) offer, their implementation is limited in practice due to the limited communication resources. We propose a novel distributed approach for the resource allocation problem in NCSs by which the subsystems can coordinate to access the network. More specifically, we develop a deterministic distributed scheme with which the subsystem with the highest cost is selected, based only on local information without requiring explicit communication between the subsystems. The efficiency of our scheme is demonstrated via simulations and it is compared with a centralized approach and other relevant approaches.

关键词： Networked control systems distributed channel access cost of information loss timers

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A Priority-Based distributed channel access Mechanism for Control over CAN-like Networks

A Priority-Based Distributed Channel Access Mechanism for Co...

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European Control Conference (ECC)

作者： Wang, Shengquan Farjam, Tahmoores Charalambous, Themistoklis Aalto Univ Dept Elect Engn & Automat Sch Elect Engn Espoo Finland

ISBN: (纸本)9789463842365

In this work, we study the distributed channel access problem for multiple subsystems equipped with smart sensors sharing a capacity-limited communication network to perform their control tasks. We propose a fully distributed scheme to use the limited communication resources efficiently with respect to a quadratic cost which reflects the control performance. More specifically, we adopt a priority assignment scheme which consists of two layers: (i) a dynamic priority that corresponds to the time-varying criticality of transmission for each subsystem, and (ii) a pre-specified static priority which ensures that channel access is collision-free. We first demonstrate how the dynamic priorities can be manipulated to allocate the resources with respect to the chosen cost. Next, we propose a synchronization method which enables fully distribute implementation over controller area network (CAN) hardware. We validate the compatibility of our method with the mature hardware technology of CAN by hardware-in-the-loop simulations. Finally, we demonstrate the efficacy of our proposed scheme and evaluate its performance in large-scale networks via simulation.

关键词： Networked control systems distributed channel access cost of information loss controller area network

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Timer-Based distributed channel access in Networked Control Systems over Known and Unknown Gilbert-Elliott channels 18

Timer-Based Distributed Channel Access in Networked Control ...

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18th European Control Conference (ECC)

作者： Farjam, Tahmoores Charalambous, Themistoklis Wymeersch, Henk Aalto Univ Sch Elect Engn Dept Elect Engn & Automat Espoo Finland Chalmers Univ Technol Dept Elect Engn Gothenburg Sweden

ISBN: (纸本)9783907144008

In this paper, we consider a system consisting of multiple (possibly heterogeneous) decoupled control subsystems which aim at communicating with their corresponding controllers via shared (possibly) time-varying wireless channels. To address the resource allocation problem in a distributed fashion, we propose a timer-based channel access mechanism in which the subsystem with the smallest timer value, in a channel, claims the slot for transmission in that specific channel. The value of the timer is inversely proportional to a cost which is a function of the temporal correlation in the channel variation and the subsystem state. This cost can be calculated individually and does not require explicit communication between the subsystems, since it is based on locally available information only. The temporal correlation in the channel variation may be unknown and, in such cases, each subsystem tries to deduce it via machine learning techniques. The performance of our proposed mechanism is demonstrated via simulations.

关键词： Wireless networked control systems distributed channel access cost of information loss Gilbert-Elliott channel Bayesian inference

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Timer-Based distributed channel access for Control Over Unknown Unreliable Time-Varying Communication channels 18

Timer-Based Distributed Channel Access for Control Over Unkn...

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18th European Control Conference (ECC)

作者： Farjam, Tahmoores Charalambous, Themistoklis Wymeersch, Henk Aalto Univ Sch Elect Engn Dept Elect Engn & Automat Espoo Finland Chalmers Univ Technol Dept Elect Engn Gothenburg Sweden

ISBN: (纸本)9783907144008

We consider the resource allocation problem for a system consisting of multiple control subsystems that share an unknown unreliable time-varying wireless channel. We propose a novel method for granting channel access deterministically without requiring information exchange between subsystems, based on local timers for prioritizing channel access with respect to a local cost that takes into account the (initially unknown) channel conditions. We propose a novel setup which has the capability of learning the parameters of imperfect communication links while ensuring distributed collision-free implementation. More specifically, we adopt learning algorithms for estimating the channel quality and, hence, define the local cost as a function of this estimation and control performance. The efficacy of this mechanism is evaluated via simulations.

关键词： Wireless networked control systems distributed channel access cost of information loss exploration-exploitation bandits

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Optimal Secure channel access in distributed Cooperative Networks With Untrusted Relay

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IEEE WIRELESS COMMUNICATIONS LETTERS 2023年第6期12卷 1091-1095页

作者： Xie, Jia Zhang, Zhou Atapattu, Saman Ye, Yan Zhang, Hailin Xidian Univ Sch Telecommun Engn Xian 710126 Peoples R China Tianjin Artificial Intelligence Innovat Ctr Tianjin 300457 Peoples R China RMIT Univ Sch Engn Melbourne Vic 3000 Australia

This letter investigates optimal channel access strategies to improve secure communications over a distributed cooperative wireless network with multiple user pairs and an untrusted amplify-and-forward (AF) relay. The user pairs communicate directly or via the relay. To enable secure communication, we formulate a channel access problem to maximize the average secrecy system throughput with destination-based jamming. Using optimal sequential planned decision theory, we propose an optimal channel access strategy where the winning user pair uses direct transmission, cooperative AF relaying, or cooperative jamming in an adaptive manner. We rigorously prove the optimality of the solution and provide a distributed channel access algorithm based on the pure threshold structure, which is easy to implement. Numerical results demonstrate effectiveness and efficiency of the proposed strategy compared to alternatives.

关键词： Relays Signal to noise ratio Jamming Throughput Wireless sensor networks Probes Device-to-device communication Cooperative networks distributed channel access jamming relay secrecy throughput

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