Rate Control with Spatial Reuse for Wi-Fi 6 Dense Deployments
To improve the performance of Wi-Fi networks in dense deployments, the recent IEEE 802.11ax standard introduces a palette of features improving spatial reuse. A key property of these features is dynamic changes in transmit power and the interference from the neighboring devices. The paper explains the basic operation of spatial reuse features and shows that their efficiency significantly depends on how the stations select appropriate modulation and coding schemes taking into account the variable transmission conditions. Nevertheless, the majority of existing studies in the literature leave this effect out of consideration, assuming an ideal rate control algorithm and obtaining wrong results. The paper fills this gap and presents a novel statistics-based rate control algorithm that selects modulation and coding schemes taking into account the effects induced by the recent spatial reuse features. With extensive simulation, it is shown that the algorithm significantly outperforms the existing rate control algorithms, providing up to 50% higher goodput and three times lower latencies.
To improve the reliability of data delivery, in Wi-Fi networks stations can reserve for their transmissions periodic time intervals of the same duration in which they are allowed to transmit, while adjacent stations do not have that right. Here there arises the problem of choosing the parameters of reserved intervals that would ensure quality of service requirements for transmitted data in the smallest possible amount of reserved channel time. We consider the data transmission process in periodic intervals with the block acknowledgement policy that lets us reduce the costs by acknowledgement the set of packets with a single service message. We propose a method for mathematical modeling of such a transmission.
Для передачи по mesh-сети потоковых данных, предъявляющих высокие требования к качеству обслуживания, удобно использовать описанный в стандарте IEEE 802.11s механизм MCCA детерминированного доступа к среде. При использовании этого механизма станции резервируют для своих передач определенные периодически повторяющиеся интервалы времени, тем самым получая бесконкурентный доступ к каналу связи. Однако, чтобы обеспечить успешную доставку данных в условиях помех, необходимо устанавливать дополнительные резервирования под повторные попытки передачи. В работе построена аналитическая модель процесса передачи неординарного потока по многошаговым беспроводным сетям с помощью механизма MCCA. Модель позволяет определить наибольший период резервирований, при котором выполнены требования на время доставки и долю потерянных пакетов.
Proceedings of 16th International Conference on Next Generation Wired/Wireless Advanced Networking
Proceedings of International Wireless Communications and Mobile Computing Conference (IWCMC) 2016
Proceedings of Wireless Communications and Networking Conference (WCNC) 2016
While celebrating the 21st year since the very first IEEE 802.11 “legacy” 2 Mbit/s wireless Local Area Network standard, the latest Wi-Fi newborn is today reaching the finish line, topping the remarkable speed of 10 Gbit/s. IEEE 802.11ax was launched in May 2014 with the goal of enhancing throughputper-area in high-density scenarios. The first 802.11ax draft versions, namely D1.0 and D2.0, were released at the end of 2016 and 2017. Focusing on a more mature version D3.0, in this tutorial paper, we help the reader to smoothly enter into the several major 802.11ax breakthroughs, including a brand new OFDMAbased random access approach as well as novel spatial frequency reuse techniques. In addition, this tutorial will highlight selected significant improvements (including PHY enhancements, MUMIMO extensions, power saving advances, and so on) which make this standard a very significant step forward with respect to its predecessor 802.11ac
In Wi-Fi networks, preliminary channel reservation protects transmissions in reserved time intervals from collisions with neighboring stations. However, making changes in established reservations takes long time spent on negotiating changes with neighboring stations and dissemination of information about these changes. This complicates serving of Variable Bit Rate (VBR) flows which intensity varies with time, what leaves no choice but to reserve some additional time for handling data bursts and packet retransmissions (caused by random noise and interference from remote stations). In the paper, we consider a more flexible approach when bursts and retransmissions are handled by some random access method while a constant part of an input flow is served in preliminarily reserved intervals. We build a mathematical model of a VBR flow transmission process with this heterogeneous access method and use the model to find transmission parameters which guarantee that Quality of Service requirements of the flow are satisfied at the minimal amount of used channel time.
Generalized error-locating codes are discussed. An algorithm for calculation of the upper bound of the probability of erroneous decoding for known code parameters and the input error probability is given. Based on this algorithm, an algorithm for selection of the code parameters for a specified design and input and output error probabilities is constructed. The lower bound of the probability of erroneous decoding is given. Examples of the dependence of the probability of erroneous decoding on the input error probability are given and the behavior of the obtained curves is explained.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.