Buffer State Research Articles

Joint Buffer-Aided Hybrid-Duplex Relay Selection and Power Allocation for Secure Cognitive Networks With Double Deep Q-Network

This paper applies the reinforcement learning in the joint relay selection and power allocation in the secure cognitive radio (CR) relay network, where the data buffers and full-duplex jamming are applied at the relay nodes. Two cases are considered: maximizing the throughput with the delay and secrecy constraints, and maximizing the secrecy rate with the delay constraint, respectively. In both cases, the optimization relies on the buffer states, the interference to/from the primary user, and the constraints on the delay and/or secrecy. This makes it mathematically intractable to apply the traditional optimization methods. In this paper, the double deep Q-network (DDQN) is used to solve the above two optimization problems. We also apply the a-priori information in the CR network to improve the DDQN learning convergence. Simulation results show that the proposed scheme outperforms the traditional algorithm significantly.

A novel QoE based cross-layer scheduling scheme for video applications in 802.11 wireless LANs

In the past two decades, 802.11 based Wireless Local Area Networks (WLANs) have gained popularity in offering Internet services and increasingly supporting data driven video streaming applications. Such services demand enhanced view quality to all the end-users in the network. However, due to the sharing of limited resources and lack of proper scheduling mechanisms, WLANs are unable to meet the requirements of numerous video users and provide them better quality. Therefore, an effective resource scheduling approach is needed that can achieve high user satisfaction for the ever changing user needs for quality video viewing. In this paper, a Quality of Experience based Cross-Layer Scheduling (QoECLS) scheme to enhance the user experience for video applications in WLANs is proposed. Here, the Mean Opinion Score has been used as a measure to evaluate the user experience. In order to provide the average user throughput with guarantee of fairness among users, the QoECLS scheme uses cross-layer information from the application and physical layer, respectively. The QoECLS algorithm allocates transmission resources by considering application feedback along with channel state information and buffer status. The performance of the QoECLS approach was extensively studied through simulations and the results showed an improvement in user experience and throughput, while maintaining fairness among the users. In terms of throughput, the proposed scheme achieves 25%, 45 %, and 50% improvement compared to QoE Aware Scheduling scheme, Modified-Largest Weighted Delay First scheduler and Exponential-Proportional Fair scheduler, respectively.

Relay Selection for Energy-Harvesting Relays With Finite Data Buffer and Energy Storage

Buffer-aided relaying can fully utilize the available selection gain of relay channels by allowing relays to store the received packets in the data buffers when the first-hop and second-hop channels are mismatched in quality. For energy-constrained Internet-of-Things (IoT) networks, some relays may lack sufficient energy to forward the buffered packets even their relay-to-destination channels are strong enough, leading to significant performance loss. This work studies buffer-aided relaying for relays that accumulate the energy harvested from source signal using finite-size energy buffers. A relay selection scheme considering both data buffer and energy buffer status is proposed and its performance is theoretically analyzed through Markov-chain modeling. Due to the complex behavior of dual buffers, the power consumption for reporting buffer status is first ignored in the theoretical analysis, which is then extended to, including feedback energy consumption. We validate the accuracy of the theoretical analysis and extensively discuss the performance of the proposed relay selection scheme subject to numerous key parameters. Numerical results demonstrate that the proposed relay selection scheme can fully exploit the diversity gain of multiple relays when ignoring energy consumption of feedback. With nonnegligible feedback energy consumption, the proposed relay selection scheme still significant outperforms some existing buffer-aided relay selection schemes.

QoS‐Oriented Optimal Relay Selection in Cognitive Radio Networks

A cognitive radio network can be employed in any wireless communication systems, including military communications, public safety, emergency networks, aeronautical communications, and wireless‐based Internet of Things, to enhance spectral efficiency. The performance of a cognitive radio network (CRN) can be enhanced through the use of cooperative relays with buffers; however, this incurs additional delays which can be reduced by using virtual duplex relaying that requires selection of a suitable relay pair. In a virtual duplex mode, we mimic full‐duplex links by using simultaneous two half‐duplex links, one transmitting and the other one receiving, in such a way that the overall effect of duplex mode is achieved. The relays are generally selected based on signal‐to‐interference‐plus‐noise ratio (SINR). However, other factors such as power consumption and buffer capacity can also have a significant impact on relay selection. In this work, a multiobjective relay selection scheme is proposed that simultaneously takes into account throughput, delay performance, battery power, and buffer status (i.e., both occupied and available) at the relay nodes while maintaining the required SINR. The proposed scheme involves the formulation of four objective functions to, respectively, maximize throughput and buffer space availability while minimizing the delay and battery power consumption. The weighted sum approach is then used to combine these objective functions to form the multiobjective optimization problem and an optimal solution is obtained. The assignments of weights to objectives have been done using the rank sum (RS) method, and several quality‐of‐service (QoS) profiles have been considered by varying the assignment of weights. The results gathered through simulations demonstrate that the proposed scheme efficiently determines the optimal solution for each application scenario and selects the best relay for the respective QoS profile. The results are further verified by using the genetic algorithm (GA) and particle swarm optimization (PSO) techniques. Both techniques gave identical solutions, thus validating our claim.

Performance evaluation of congestion aware transmission opportunity scheduling scheme for 802.11 wireless LANs

In the last two decades, Wireless Local Area Networks (WLANs) based on 802.11 have become crucial in offering Internet services with high data transmission rates. Under crowded scenarios like airports, shopping centers, and stadiums, WLANs can be easily congested due to their random access nature and limited operational capability. This may result in a reduced user multimedia experience. With a proper Transmission Opportunity (TXOP) allocation and scheduling scheme, the user service quality could be improved under such scenarios. In this paper, a Congestion-Aware Transmission Opportunity (CA-TXOP) scheme is proposed, allocating transmission resources by considering network level congestion and information like buffer status, channel quality, and data rates. The CA-TXOP scheme prioritizes congested and noncongested user stations and improves the overall network performance. Simulation results show that the CA-TXOP scheme attained 45%, 35%, and 20% enhancement compared with Fixed, Bi-level, and FRA-TXOP scheduling schemes. Such scheme applies to future congested scenarios like smart buildings and organizations that require satisfying video quality to all the user stations.

On Time-Dependent Queue-Size Distribution in a Model With Finite Buffer Capacity and Deterministic Multiple Vacations With Applications to LTE DRX Mechanism Modeling

A finite-capacity queueing model with the arrival stream of messages governed by the compound Poisson process and generally-distributed processing times is investigated. Whenever the system becomes empty (the server becomes idle), a number of deterministic independent vacations of equal length are initialized as far as at least one message is detected in the accumulating buffer at the completion epoch of one of them. During vacations the service process is suspended completely, while after finishing the last vacation it restarts normally. Identifying Markov moments in the evolution of the system and using the Korolyuk’s potential method, the compact-form representation for the transient queue-size distribution conditioned by the initial buffer state is found in terms of its Laplace transform. The considered model has potential applications in modeling the energy saving LTE DRX mechanism. A detailed simulation and numerical study is attached.

A Proposed Adaptive Bitrate Scheme Based on Bandwidth Prediction Algorithm for Smoothly Video Streaming

A robust video-bitrate adaptive scheme at client-aspect plays a significant role in keeping a good quality of video streaming technology experience. Video quality affects the amount of time the video has turned off playing due to the unfilled buffer state. Therefore to maintain a video streaming continuously with smooth bandwidth fluctuation, a video buffer structure based on adapting the video bitrate is considered in this work. Initially, the video buffer structure is formulated as an optimal control-theoretic problem that combines both video bitrate and video buffer feedback signals. While protecting the video buffer occupancy from exceeding the limited operating level can provide continuous video streaming, it may also cause a video bitrate oscillation. So the video buffer structure is adjusted by adding two thresholds as operating points for overflow and underflow states to filter the impact of throughput fluctuation on video buffer occupancy level. Then a bandwidth prediction algorithm is proposed for enhancing the performance of video bitrate adaptation. This algorithm's work depends on the current video buffer level, video bitrate of the previous segment, and iterative throughput measurements to predict the best video bitrate for the next segment. Simulation results show that reserving a bandwidth margin is better in adapting the video bitrate under bandwidth variation and then reducing the risk of video playback freezing. Simulation results proved that the playback freezing happens two times: firstly, when there is no bandwidth margin used and secondly, when the bandwidth margin is high while smooth video bitrate is obtained with moderate value. The proposed scheme is compared with other two schemes such as smoothed throughput rate (STR) and Buffer Based Rate (BBR) in terms of prediction error, QoE preferences, buffer size, and startup delay time, then the proposed scheme outperforms these schemes in attaining smooth video bitrates and continuous video playback.

The Long War for Texas: Maroons, Renegades, Warriors, and Alternative Emancipations in the Southwest Borderlands, 1835–1845

In the Southwest Borderlands, marronage and insurrection defined the long war against slavery and empire waged by Indigenous peoples and African Americans following the Texas Revolution of 1835–36. The egalitarian politics and militarized commerce of Native societies empowered marginalized communities by providing the spatial, material, and ideological resources for emancipatory struggles. Allied with Mexico, multiethnic bands of warriors, fugitives, and renegades built fortified villages, planted provision grounds, raised livestock, and recruited outsiders. These efforts culminated in uprisings by Tejanos and enslaved African Americans, as well as an attempt to establish a Pan-Indian buffer state north of the Rio Grande. With their combined force, these cohorts posed grave problems for the Anglo-Texan slave state and made its independence tentative and vulnerable. Taking seriously the aspirations of maroon communities, this article shifts our understanding of emancipation and sovereignty from a racialized and nationalist framework to a more fluid terrain that reveals how the dispossessed galvanized new methods of renewal.

LoLa4SOR: Leveraging Successive Transmissions for Low-Latency Buffer-Aided Opportunistic Relay Networks

Buffer-aided (BA) relaying improves the diversity of cooperative networks often at the cost of increasing end-to-end packet delays. This characteristic renders BA relaying unsuitable for delay-sensitive applications. However, the increased diversity makes BA relaying appealing for ultra-reliable communications. Towards enabling ultra-reliable low-latency communication (URLLC), we aim at enhancing BA relaying for supporting delay-sensitive applications. In this paper, reliable full-duplex (FD) network operation is targeted and for this purpose, hybrid relay selection algorithms are formulated, combining BA successive relaying (SuR) and delay- and diversity-aware (DDA) half-duplex (HD) algorithms. In this context, a hybrid FD DDA algorithm is presented, namely LoLa4SOR, switching between SuR and HD operation. Additionally, a low-complexity distributed version is given, namely d-LoLa4SOR, providing a trade-off among channel state information requirements and performance. The theoretical analysis shows that the diversity of LoLa4SOR equals to two times the number of available relays $K$ , i.e., $2K$ , when the buffer size $L$ is greater than or equal to 3. Comparisons with other HD, SuR and hybrid algorithms reveal that LoLa4SOR offers superior outage and throughput performance while, the average delay is reduced due to SuR-based FD operation and the consideration of buffer state information for relay-pair selection. d-LoLa4SOR, as one of the few distributed algorithms in the literature, has a reasonable performance that makes it a more practical approach.

A Proposed Adaptive Bitrate Scheme Based on Bandwidth Prediction Algorithm for Smoothly Video Streaming

A robust video-bitrate adaptive scheme at client-aspect plays a significant role in keeping a good quality of video streaming technology experience. Video quality affects the amount of time the video has turned off playing due to the unfilled buffer state. Therefore to maintain a video streaming continuously with smooth bandwidth fluctuation, a video buffer structure based on adapting the video bitrate is considered in this work. Initially, the video buffer structure is formulated as an optimal control-theoretic problem that combines both video bitrate and video buffer feedback signals. While protecting the video buffer occupancy from exceeding the limited operating level can provide continuous video streaming, it may also cause a video bitrate oscillation. So the video buffer structure is adjusted by adding two thresholds as operating points for overflow and underflow states to filter the impact of throughput fluctuation on video buffer occupancy level. Then a bandwidth prediction algorithm is proposed for enhancing the performance of video bitrate adaptation. This algorithm's work depends on the current video buffer level, video bitrate of the previous segment, and iterative throughput measurements to predict the best video bitrate for the next segment. Simulation results show that reserving a bandwidth margin is better in adapting the video bitrate under bandwidth variation and then reducing the risk of video playback freezing. Simulation results proved that the playback freezing happens two times: firstly, when there is no bandwidth margin used and secondly, when the bandwidth margin is high while smooth video bitrate is obtained with moderate value. The proposed scheme is compared with other two schemes such as smoothed throughput rate (STR) and Buffer Based Rate (BBR) in terms of prediction error, QoE preferences, buffer size, and startup delay time, then the proposed scheme outperforms these schemes in attaining smooth video bitrates and continuous video playback.

The Far East during the Great Russian Revolution (1917—1922)

The publication is devoted to the history of the Far East during the Great Russian Revolution (1917—1922). Attention is drawn to the fact that in the period from February to October 1917, dual power arose in the Far East — a kind of form of social compromise. The path to power of the Soviets went through one of the most difficult and tragic periods in the history of Russia — the period of the Civil War, which, according to the modern historical and cultural standard, is considered as part of the Great Russian Revolution. During the Civil War, various political forces launched a struggle for the implementation of their own model of the state structure of Russia. This period is characterized by almost complete disintegration of the state, mass destruction and casualties, a sharp weakening of the country's international position. This state of affairs was taken advantage of by external enemies (and former allies) of Russia. Intervention during the Civil War had a significant impact on its course, duration and fierceness. This process was attended by 14 foreign countries, including such as England, the USA, Japan, France. It is emphasized that Japan played the greatest role in the intervention in the region. The features of the partisan movement, the role of the buffer state — the Far Eastern Republic (FDA) in the victory over the interventionists and representatives of the white movement are considered.

Трудный путь становления корейского отдела Восточной секции Коммунистического интернационала. 1919-й – первая половина 1920-х гг.

The article highlights the process of formation of the Korean Department of the Eastern section of the ICCA under the conditions of existence of the buffer state — the Far Eastern Republic. It was to strive for geopolitical compromise in face of the Civil War and the Allied Intervention. The paper discusses conditions for establishment and reasons for further expansion of the Korean section. On the basis of documents from central and regional archives that are being thus introduced into the first scientific use, the contradictions of the national section formation are shown, the positions of the warring parties and the role of Soviet Russia representatives in the settlement of conflicts are highlighted. The conclusion is made about further directions of work with Korean communists. The past provides an opportunity to take a critical look at the events of a century ago, while the opening of the Comintern archives allows the open press to saturate its content with new data. The main body of unpublished documents on the activities of the Communist International is contained in the fond 495 of the Russian State Archive of Socio-Political History, however, information on some aspects may be found in other federal and regional archives. It is no secret that foreign communists played their role in the foreign policy of Soviet Russia, and their help was big. However, the process of bringing them to work in the interests of the RSFSR has not yet been fully studied. Expediency, cost, and consequences of their work may be arguable, but only one conclusion is allowed: this page of national history should not be forgotten, it has to find its researchers. Recently, the study of the activities of departments and sections of the Communist international has not been popular among researchers either. The notions of ideological work have fallen by the wayside, pushed away by the Soviet past of the Comintern departments and sections. However, in our view, some aspects of the activities of divisions and sections of the Comintern remain relevant.

Durand Line Agreement 1893: Myths and Reality

This paper attempts to analyse the myths about the Durand Line Agreement between the British India and Afghanistan in 1893. Nineteenth century is considered as the century of imperialism. The two great powers i.e Great Britain and Russia were in competition to fulfill their imperialistic designs. Great Britain succeeded in taking full control of India and Russia annexed Khiva, Bokhara and Khokand currently Central Asian republics until 1870. Afghanistan was the only state left between the two giants. The British India tested its muscles in Afghanistan in 1839 and 1878 but failed to consolidate. The fear of Russian advancement during the Great Game compelled the British India to declare Afghanistan a buffer state and demarcate its boundaries. They started working on it immediately after the second Anglo-Afghan war in 1885. Resultantly the western boundaries of India were secured through the famous Durand Line Agreement in 1893 between Afghanistan and British India. After the independence of Pakistan in 1947 a lot of myths emerged related to this agreement. This paper focuses on those myths and its reality in order to clarify the misunderstanding related to this much debated agreement.

Optimal Two-Way Buffer-Aided Relaying: Achieving the Best Outage and Delay Performance With Small Buffer Sizes

In this paper, we consider two-way relaying where two users exchange information through a decode-and-forward (DF) buffer-aided (BA) relay. We formulate a generic BA relaying protocol that is based on both the channel and buffer states and that can be parameterized by two parameters. Through a Markov chain analysis, we show how these parameters can be selected for the sake of minimizing the outage probability (OP) and average packet delay (APD) for asymptotic values of the signal-to-noise ratio. The performed optimization sheds more light on the impact of the buffer sizes on the triad of diversity order, coding gain and APD that can be contemplated. In particular, we prove that equipping the relay with two buffers of size three each is sufficient for extracting the full capabilities of two-way BA relaying. Depending on the network setup, one or both buffer sizes can be further reduced to two at the expense of a reduced coding gain without affecting the diversity order and asymptotic APD. Simulations under the generalized $\kappa -\mu $ fading demonstrate the appropriateness of the performed optimization of the relaying parameters and buffer sizes.

Design and Evaluation of Buffer-Aided Cooperative NOMA With Direct Transmission in IoT

The high spectrum efficiency of nonorthogonal multiple access (NOMA) is attractive to solve the massive number of connections in the Internet of Things (IoT). This article investigates a buffer-aided cooperative NOMA (C-NOMA) system in the IoT, where the intended users are equipped with buffers for cooperation. The direct transmission from the access point to the users and the buffer-aided cooperative transmission between the intended users are coordinated. In particular, a novel buffer-aided C-NOMA scheme is proposed to adaptively select a direct or cooperative transmission mode, based on the instantaneous channel state information and the buffer state. Then, the performance of the proposed scheme, in terms of the system outage probability and average delay, is theoretically derived with closed-form expressions. Furthermore, the full diversity order of three is demonstrated to be achieved for each user pair if the buffer size is not less than three, which is larger than conventional nonbuffer-aided C-NOMA schemes whose diversity order is only two in the considered C-NOMA system in the IoT.

Performance of Two-Hop Links With an Energy Buffer-Aided IoT Source and a Data Buffer-Aided Relay

In this article, we analyze the performance of a two-hop communication link between an energy-buffer-equipped IoT-type self-sustaining source and a destination, aided by a data-buffer-equipped relay. The source harvests radio-frequency energy from the ambience and stores it in an energy buffer. Using a discrete-time continuous-state Markov chain to model the energy buffer and a discrete-state Markov chain to model the data buffer, we analyze outage and throughput performance of the link. In typical applications, feedback of channel state information and buffer state information is not feasible, so simple link selection schemes are evolved. In the first only buffer-status (OBS) scheme, link selection is based on the energy-buffer status alone. A modified OBS scheme is then suggested, and its performance is analyzed. The third scheme uses both energy-buffer status and first-hop channel knowledge for link selection. Expressions are derived for throughput and limiting distributions of stored energy with all the three schemes. We show how the continuous-state energy buffer and the discrete-state data buffer can both be balanced while maximizing the throughput by suitable choice of the source transmit power, relay transmit power, and target information rates at the source and the relay. We also analyze statistical properties of the energy-buffer size with these schemes. The derived analytical expressions are validated by the Monte Carlo simulations.

Throughput Maximization for full-duplex two-way relay with finite buffers

<div>Optimal queueing control of multi-hop networks remains a challenging problem, e</div><div>specially in two-way relaying systems, even in the most straightforward scenarios.</div><div>In this paper, we explore two-way relaying having a full-duplex decode-and-forward</div><div>relay with two fifinite buffers. Principally, we propose a novel concept based on the</div><div>multi-agent reinforcement learning (that maximizes the cumulative network through</div><div>put) based on the combination of the buffer states and the lossy links; a decision is</div><div>generated as to whether it can transmit, receive or even simultaneously receive and</div><div>transmit information. Towards this objective, chieflfly, based on the queue state transi</div><div>tion and the lossy links, an analytic Markov decision process is proposed to analyze</div><div>this scheme, and the throughput and queueing delay are derived. Our numerical results</div><div>reveal exciting insights. First, artifificial intelligence based on reinforcement learning</div><div>is optimal when the length of the buffer is superior to a certain threshold. Second, we</div><div>demonstrate that reinforcement learning can boost transmission effificiency and prevent</div><div>buffer overflflow.</div>

On Maximizing Max–Min Source Rate in Wireless-Powered Internet of Things

Future Internet-of-Things (IoT) networks will consist of radio-frequency (RF) energy harvesting devices that are charged by solar-powered power beacons (PBs). To this end, this article aims to maximize the minimum data rate of devices acting as sources operating in a multihop IoT network. The main problem is to decide the amount of energy delivered by solar-powered PBs, routing of data from each source, and link scheduling, which determines the capacity of links. To this end, we make two contributions. First, we present a linear program (LP) to optimize the max–min rate of sources. Our LP considers nonlinear RF conversion at devices, energy storage loss at devices due to the imperfect battery, and time-varying channel quality, which affect the amount of energy harvested by devices. The second contribution is a novel distributed protocol called distributed max–min rate allocation (D-MRA), whereby devices only need local information, such as their battery and data buffer state to make decisions. Our results show that the max–min rate of D-MRA is 58.25% that of LP, which requires global information, in all tested cases.

Scene-level two-pass video rate controller for H.265/HEVC standard

A scene-level two-pass video rate controller for high efficiency video coding (HEVC) standard is proposed in this paper. The proposed rate controller is suitable for many pre-recorded applications in which encoded videos are transferred later on through a communication channel with limited bandwidth and buffering constraint. This rate controller operates in two passes. In the first pass, the video sequence is compressed and relevant information is collected. In the second pass, an optimal base quantization parameter (QP) for each video scene is calculated by simplifying the λ-domain rate-distortion model. Then, using the optimal base QP and the known QP cascading technique, a QP is computed for each picture in the scene. In this way, the quality of the compressed video is kept relatively constant during a scene and thus it provides a high-level perceptual quality for the compressed video. The base QP may be slightly modified during the second pass encoding by a fuzzy controller according to the second pass encoding results and the buffer status. The proposed rate controller has been implemented on H.265/HEVC standard reference software. Experimental results show that in comparison with the constant QP encoding and three known rate control algorithms the proposed algorithm provides a high-level quality for tested video sequences while the required buffering delay is low and the available bandwidth is fully used.

Russian Culture as Alternative to Global and European Continental Culture in the Context of the Civilizational Approach and “Ideology” and “Post-ideology” Phenomena

The article offers a concise analysis of three cultures (global (Anglo-American), European continental and Russian) in the context of the civilizational approach and such phenomena as ideology (national-wide) and post-ideology. The author gives the analysis of the metamorphosis of ideology into post-ideology, as well as their connection to the concept of “cultural code”. He explains how in the course of the transition from ideology to post-ideology, there happens the “rise from the depths of culture” of the values that have not changed since pre-political times, and constitute the cultural code. He also explains why, when ideology is transformed into post-ideology, the “death of the ideologue” occurs and some values and rights become “natural”. The differences between the three cultures under consideration are shown by the example of some traits-values, and the intermediate (buffer) state of the European continental culture in relation to the global and Russian culture. The author suggests to study the “cultural code” using sociological and political science tools, as well as philosophical analysis of texts. The manifestation of the cultural code is associated with the response of its carriers to an external challenge - a situation.