Change Of Channel Quality Research Articles

Artificial Intelligence Aided Joint Bit Rate Selection and Radio Resource Allocation for Adaptive Video Streaming over F-RANs

Recently, fog-computing-based radio access networks (F-RANs) have been conceptualized to provide high quality of experience (QoE) for adaptive bit rate (ABR) streaming, where additional computing capacity is supplemented on fog nodes to facilitate complicated cross-layer optimization (i.e., joint bit rate selection and radio resource allocation). However, finding an optimal global solution with acceptable complexity is still infeasible by the conventional optimization methods. In this work, we propose an artificial intelligence (AI) aided joint bit rate selection and radio resource allocation scheme referred to as iABR, which provides a new vision for handling the over-complicated optimization in F-RANs. Based on multi-agent hierarchy deep reinforcement learning, the proposed iABR can dynamically allocate radio resource and select bit rate in a multiuser scenario, by perceiving the network environment and clients' player information. Moreover, long short-term memory (LSTM) is employed by the iABR algorithm, which enables accurate prediction of the change of channel quality by learning the history of the wireless channel. Hence, iABR is able to adjust the action policy in advance to accommodate the future channel quality for avoiding bit rate fluctuation. According to the experimental results, the iABR exhibits higher QoE in terms of high average bit rate, low rebuffering ratio, and average bit rate variance. Last but not least, the QoE performance of all the clients are fairly guaranteed by the iABR algorithm, enhancing the practicality of AI-driven F-RANs for multimedia service delivery.

An adaptive channel estimation algorithm for millimeter wave cellular systems

The large bandwidth available with mmWave (millimeter Wave) makes it a promising candidate for 5th generation cellular networks. Proper channel estimation algorithms must be developed to enable beamforming in mmWave systems. In this paper, we propose an adaptive channel estimation algorithm that exploits the poor scattering nature of the mmWave channel and adjusts the training overhead adaptively with the change of channel quality for mmWave cellular systems. First, we use a short training sequence to estimate the channel parameters based on the two-dimensional discrete Fourier transform method. Then, we design a feedback scheme to adjust the length of the training sequence under the premise of ensuring the accuracy of the channel estimation. The key threshold in the feedback scheme is derived and its influence on the accuracy of the estimation results is analyzed. Simulation results confirm that the proposed algorithm can adjust the length of the training sequence adaptively according to the current channel condition maintaining a stable estimation accuracy.

Opportunistic multicasting for single frequency networks

AbstractWith the growth of multimedia traffic over mobile networks, multicast becomes one of more effective transmission approaches to be widely considered. The Multimedia Broadcast multicast service Single Frequency Network (MBSFN) has been introduced for long term evolution to improve signal‐to‐interference‐plus‐noise ratio at the cell edges, while selecting efficient modulation and coding schemes (MCS) for transmission is still an open issue. Unlike existing solutions in literature, the opportunistic multicasting concept is adopted in this work to aggressively enhance the spectrum efficiency (SE) of single frequency networks. Based on the derived model of effective SE in extended MCS adaptation intervals, we propose a statistical feedback‐based approach to achieve opportunistic multicasting in MBSFN. The algorithm carefully selects the MCS complying with the adaptation need for channel quality changes and enabling high bottleneck user SE under reduced feedbacks. Comparing with other schemes for a single stream setup, the simulations show up to 340% higher SE over non‐opportunistic method and 25% over the second best method maximizing the average SE. The number of successfully transmitted streams in a multi‐stream scenario increased by 250% over the non‐opportunistic approach and 40% over the average SE maximizing approach. Copyright © 2016 John Wiley & Sons, Ltd.

다중큐잉 실시간 트래픽쉐이핑을 적용한 네트워크간 VPN 지원 유무선공유기 시스템

In order to build network infrastructure to implement the aforementioned advantages enabling smart device users to work anywhere, professional support and expensive VPN devices are required. This is a barrier to supplying VPN devices to small and medium-sized institutes. To address this issue, this study aims to implement OpenVPN, OpenSSH and iproute based on the OpenWRT platform which is an embedded OS for open networks in affordable open wired/wireless gateway H/W platforms to support the inter-network VPN. In addition, the network environment can be maintained optimal by applying a multi-queuing real-time traffic shaping technology to VPN tunnels, although channel quality changes.

Study of multi-armed bandits for energy conservation in cognitive radio sensor networks.

Technological advances have led to the emergence of wireless sensor nodes in wireless networks. Sensor nodes are usually battery powered and hence have strict energy constraints. As a result, energy conservation is very important in the wireless sensor network protocol design and the limited power resources are the biggest challenge in wireless network channels. Link adaptation techniques improve the link quality by adjusting medium access control (MAC) parameters such as frame size, data rate, and sleep time, thereby improving energy efficiency. In this paper we present an adaptive packet size strategy for energy efficient wireless sensor networks. The main goal is to reduce power consumption and extend the whole network life. In order to achieve this goal, the paper introduces the concept of a bounded MAB to find the optimal packet size to transfer by formulating different packet sizes for different arms under the channel condition. At the same time, in achieve fast convergence, we consider the bandwidth evaluation according to ACK. The experiment shows that the packet size is adaptive when the channel quality changes and our algorithm can obtain the optimal packet size. We observe that the MAB packet size adaptation scheme achieves the best energy efficiency across the whole simulation duration in comparison with the fixed frame size scheme, the random packet size and the extended Kalman filter (EKF).

Non-Intrusive Online Quality of Experience Assessment for Voice Communications

Recently user quality of experience (QoE) is employed in evaluating end user satisfaction in communications systems. Generally, current approaches for QoE assessment are obtrusive, laboratory based and offline. Estimation of user satisfaction in static manner based on mean opinion score is not directly related to instantaneous individual end user contentment. In this paper, based on correlations between user's physiological signals and her/his feelings about the service quality, a non-intrusive and user centric QoE assessment system for voice communications is developed. The findings of this study indicate that the emotional patterns in response to the changes in channel quality can be adapted to estimate the level of satisfaction in a QoE assessment system in a live manner. Based on experimental results, two categories of users are identified: sensitive and insensitive towards quality degradations. The results indicate that for the sensitive users, our non-intrusive subjective quality assessment method outperforms ITU-T P.563 standard with respect to root mean square error; while, the results are much better among the insensitive users.

A link-adapted fragment and rate matching (FaRM) MAC protocol for wireless LANs

The paper proposes a fragment and rate matching (FaRM) MAC protocol for wireless LANs to resist the frequent change of channel quality so as to increase network throughput. In wireless transmissions, channel quality varies with time. The FaRM protocol estimates channel quality by detecting current signal-to-noise ratio (SNR) through frame exchanges. A finite state Markov chain (FSMC) is utilised to predict the variation in the channel conditions during the next frame transmission. According to the results obtained from the FSMC, the FaRM protocol enables the sender to dynamically select an appropriate transmission rate as well as an acceptable fragment length to transmit, such that the reliability and time of this transmission can be improved. As a result, the FaRM protocol can not only obtain better network throughput through the selection of the high transmission rate, but it can also increase the successful transmission rate by the determination of a suitable fragment length. Simulation results show that the FaRM protocol has better performance, higher transmission reliability, and lower transmission delay by FaRM in comparison to the related work.

Overview of Wireless Mesh Networks

Wireless Mesh Networks (WMNs) introduce a new paradigm ‎wireless broadband Internet access by providing high data ‎service, scalability, and self-healing abilities at reduced ‎‎high throughput for multi-cast applications (e.g. ‎streaming broadcast) in WMNs is challenging due to the ‎and the change of channel quality. To overcome ‎issue, cross-layer has been proposed to improve the ‎ormance of WMNs. ‎coding is a powerful coding technique that has been ‎to be the very effective in achieving the maximum multi-cast ‎In addition to achieving the multi-cast ‎network coding offers other benefits such as load ‎and saves bandwidth consumption. This ‎presents a review the fundamental concept types of medium access control ‎‎ layer, routing protocols, cross-layer and network ‎for wireless mesh networks. Finally, a list of directions for further research is considered. 

Adaptive Sending Rate Over Wireless Mesh Networks Using SNR

Wireless Mesh Networks (WMNs) have emerged as a key technology for the next generation of wireless networking. Instead of being another type of ad-hoc networking, WMNs diversify the capabilities of ad-hoc networks. Several protocols that work over WMNs include IEEE 802.11a/b/g, 802.15, 802.16 and LTE-Advanced. To bring about a high throughput under varying conditions, these protocols have to adapt their transmission rate. This paper proposes a scheme to improve channel conditions by performing rate adaptation along with multiple packet transmission using packet loss and physical layer condition. Dynamic monitoring, multiple packet transmission and adaptation to changes in channel quality by adjusting the packet transmission rates according to certain optimization criteria provided greater throughput. The key feature of the proposed method is the combination of the following two factors: 1) detection of intrinsic channel conditions by measuring the fluctuation of noise to signal ratio via the standard deviation, and 2) the detection of packet loss induced through congestion. The authors show that the use of such techniques in a WMN can significantly improve performance in terms of the packet sending rate. The effectiveness of the proposed method was demonstrated in a simulated wireless network testbed via packet-level simulation.

Adaptive nonuniform phase-shift-key modulation for multimedia traffic in wireless networks

The characteristics of mobile wireless communication channels fluctuate for many reasons, including movement of the radios, changes in path attenuation, and variations in interference. Several adaptive signaling techniques have been proposed for use in wideband code-division multiple-access (CDMA) systems including adaptive data rates, adaptive spreading code rates, discontinuous transmission, and multicode CDMA. We introduce adaptive signaling techniques that use nonuniform phase-shift-key (PSK) modulation. These techniques have several advantages for use in CDMA communications, and they support multimedia transmission by simultaneously delivering different types of traffic, each with its own required quality of service. The signaling methods that we propose deliver a basic message at a specified error rate and simultaneously deliver an additional message by exploiting any extra capability that is available. We show that by adapting the location of the points in a PSK constellation, the throughput can be maximized for the additional message while maintaining an acceptable error rate for the basic message. Responses to larger changes in channel quality are accomplished by adapting the PSK constellation size, signaling rate, and error-correcting code. Examples of adaptive signaling schemes that employ nonuniform PSK constellations are presented, including an application to a cellular CDMA system.