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Dynamic data rate and transmit power adjustment in IEEE 802.11 wireless LANs
Abstract and Figures
In this paper a novel link adaptation algorithm is proposed that is capable of adjusting the transmit power level and the data rate jointly to the radio channel conditions. The proposed method relies solely on link quality information available at the transmitter by employing the reception or non-reception of the acknowledgment frames as a measure of the channel quality with respect to the power level and data rate. The method is fully compatible with the 802.11 wireless LAN standard. In contrast to many other proposals, it neither relies on the RTS/CTS protocol nor requires a feedback channel to transmit link-quality estimates from the receiver to the transmitter. Different strategies for optimizing the data rate and power level are given. These depend on the scenarios considered, the number of active stations, and the service requirements. The two main strategies are either to drive the system towards the highest possible data rate and adjust the rate and power levels accordingly (“high-performance” mode) or to focus on power saving, possibly trading this for other performance criteria such as throughput or delay performance (“low-power” mode). Other special cases, such as power or rate only adaptation, are also discussed. It can be shown that in most cases the best choice for achieving low transfer times, maximizing throughput, and alleviating the hidden terminal problem is to transmit at the highest possible rates and with high power levels. This “high-performance” mode of operation also minimizes the transmission times, which in turn maximizes the time for putting idling components into a sleep mode, thereby minimizing the overall power consumption.
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... Secondly, SR has been addressed through a decentralized perspective in [18,19,20,21,11]. Most of the decentralized strategies rely on collecting feedback on several performance metrics (e.g., sensed interference, packets lost). ...
... Most of the decentralized strategies rely on collecting feedback on several performance metrics (e.g., sensed interference, packets lost). While works such as [18,19,20] propose adaptive mechanisms to adjust the CST and the transmission power, some others like [21,11] provide probabilistic approaches based on Reinforcement Learning (RL) for finding the best possible configuration. ...
... For instance, BSS C obtains the maximum performance only when BSS A suffers flow-in-the-middle throughput starvation (the same occurs for BSS B ). The CTMN that represents this situation is shown in Figure 17 Concerning the optimal max-min performance, 18 it is given when all the BSSs can ignore every single detected inter-BSS transmission, i.e., all the inter-BSS transmissions are equally treated regardless of its source. This situation is fair and, simultaneously increases the overall performance. ...
Dealing with massively crowded scenarios is one of the most ambitious goals of next-generation wireless networks. With this goal in mind, the IEEE 802.11ax amendment includes, among other techniques, the Spatial Reuse (SR) operation. The SR operation encompasses a set of unprecedented techniques that are expected to significantly boost Wireless Local Area Networks (WLANs) performance in dense environments. In particular, the main objective of the SR operation is to maximize the utilization of the medium by increasing the number of parallel transmissions. Nevertheless, due to the novelty of the operation, its performance gains remain largely unknown. In this paper, we first provide a gentle tutorial of the SR operation included in the IEEE 802.11ax. Then, we analytically model SR and delve into the new kinds of MAC-level interactions among network devices. Finally, we provide a simulation-driven analysis to showcase the potential of SR in various deployments, comprising different network densities and traffic loads. Our results show that the SR operation can significantly improve the medium utilization, especially in scenarios under high interference conditions. Moreover, our results demonstrate the non-intrusive design characteristic of SR, which allows enhancing the number of simultaneous transmissions with a low impact on the environment. We conclude the paper by giving some thoughts on the main challenges and limitations of the IEEE 802.11ax SR operation, including research gaps and future directions.
... On the other hand, SR has been addressed through a decentralized perspective in [8], [15]- [18]. Most of the decentralized strategies rely on collecting feedback on several performance metrics (e.g., sensed interference, packets lost, etc.). ...
... Most of the decentralized strategies rely on collecting feedback on several performance metrics (e.g., sensed interference, packets lost, etc.). While works such as [15]- [17] propose adaptive mechanisms to adjust the CST and/or the transmission power, some others like [8], [18] provide probabilistic approaches based on Reinforcement Learning (RL) for finding the best possible configuration. ...
... In this work, the 11ax SR operation has been implemented as part of the Spatial Flexible Continuous Time Markov Network (SFCTMN) framework [8], [29], [30]. 15 This framework allows generating the CTMN of a given scenario, according to the spatial distribution of nodes and their configuration (e.g., range of channels used, transmission power, sensitivity, etc.). It is important to highlight that additive interference is considered, which results from the combination of different simultaneous interfering transmissions. ...
Dealing with massively crowded scenarios is one of the most ambitious goals of next-generation wireless networks. With this goal in mind, the IEEE 802.11ax amendment includes, among other techniques, the Spatial Reuse (SR) operation. This operation encompasses a set of unprecedented techniques that are expected to significantly boost the performance of Wireless Local Area Networks (WLANs) in dense environments. In particular, the main objective of the SR operation is to maximize the reutilization of the medium by increasing the number of parallel transmissions. Nevertheless, due to the novelty of the operation, its performance gains remain largely unknown. In this paper, we first provide a gentle tutorial of the SR operation included in the IEEE 802.11ax, which is exhaustively overviewed. Then, we analytically model SR and delve into the new kind of inter-WLAN interactions that appear as a result. Finally, we provide a simulation-driven analysis of the potential of SR in a variety of deployments, comprising different network densities and traffic loads. Our results show that the SR operation can significantly improve the medium reutilization, especially in scenarios under high interference conditions. Moreover, we highlight the non-intrusive design feature of SR, which is meant for enhancing the number of simultaneous transmissions without affecting the environment. We conclude the paper by drawing some conclusions on the main challenges and limitations of the SR operation included in the IEEE 802.11ax, as well as on the research gaps and future directions.
... An adaptive rate and power control technique that is consistent with IEEE 802.11 operations is proposed in (Committee et al. [2016]) where Acknowledgments (ACKs) received from the receiver are used to communicate the optimization of the transmission speed, which continues to operate utilizing two basic adaptive strategies: the maximum possible rate is assisted with the least potential power; and the lowest possible power is chosen first, then the highest rate conceivable at this power is chosen. In a related manner, Power-controlled Auto Rate Fallback (PARF) and Power-Enabled Rate Fallback (PERF) were suggested in (Chevillat et al. [2005]), in which the authors extend ARF and Estimated Rate Fallback (ERF) to work with transmission power control. It is important to note that ERF is the SNR-based variant of ARF, in which each packet carries the power level, the path loss, and noise estimate from the previous packet that has been received. ...
... ERF senders estimate the SNR based on this information and establish the highest transmission rate compatible with the estimated SNR. The authors of (Chevillat et al. [2005]) discovered that PARF did not work effectively when the receiver reduced the power used for ACK messages, as they predicted. In essence, this resulted in inaccurate power reduction choices at the transmitter when these ACK packets were not received. ...
Future wireless networks require high throughput and energy efficiency. This paper studies using Reinforcement Learning (RL) to do transmission rate and power control for maximizing a joint reward function consisting of both throughput and energy consumption. We design the system state to include factors that reflect packet queue length, interference from other nodes, quality of the wireless channel, battery status, etc. The reward function is normalized and does not involve unit conversion. It can be used to train three different types of agents: throughput-critical, energy-critical, and throughput and energy balanced. Using the NS-3 network simulation software, we implement and train these agents in an 802.11ac network with the presence of a jammer. We then test the agents with two jamming nodes interfering with the packets received at the receiver. We compare the performance of our RL optimal policies with the popular Minstrel rate adaptation algorithm: our approach can achieve (i) higher throughput when using the throughput-critical reward function; (ii) lower energy consumption when using the energy-critical reward function; and (iii) higher throughput and slightly higher energy when using the throughput and energy balanced reward function. Although our discussion is focused on 802.11ac networks, our method is readily applicable to other types of wireless networks.
... An adaptive rate and power control technique that is consistent with IEEE 802.11 operations is proposed in [16] where Acknowledgments (ACKs) received from the receiver are used to communicate the optimization of the transmission speed, which continues to operate utilizing two basic adaptive strategies: the maximum possible rate is assisted with the least potential power; and the lowest possible power is chosen irst, then the highest rate conceivable at this power is chosen. In a related manner, Power-controlled Auto Rate Fallback (PARF) and Power-Enabled Rate Fallback (PERF) were suggested in [17], in which the authors extend ARF and Estimated Rate Fallback (ERF) to work with transmission power control. It is important to note that ERF is the SNR-based variant of ARF, in which each packet carries the power level, the path loss, and noise estimate from the previous packet that has been received. ...
... ERF senders estimate the SNR based on this information and establish the highest transmission rate compatible with the estimated SNR. The authors of [17] discovered that PARF did not work effectively when the receiver reduced the power used for ACK messages, as they predicted. In essence, this resulted in inaccurate power reduction choices at the transmitter when these ACK packets were not received. ...
Future wireless networks require high throughput and energy efficiency. This paper studies using Reinforcement Learning (RL) to do transmission rate and power control for maximizing a joint reward function consisting of both throughput and energy consumption. We design the system state to include factors that reflect packet queue length, interference from other nodes, quality of the wireless channel, battery status, etc. The reward function is normalized and does not involve unit conversion. It can be used to train three different types of agents: throughput-critical, energy-critical, and throughput and energy balanced. Using the NS-3 network simulation software, we implement and train these agents in an 802.11ac network with the presence of a jammer. We then test the agents with two jamming nodes interfering with the packets received at the receiver. We compare the performance of our RL optimal policies with the popular Minstrel rate adaptation algorithm: our approach can achieve (i) higher throughput when using the throughput-critical reward function; (ii) lower energy consumption when using the energy-critical reward function; and (iii) higher throughput and slightly higher energy when using the throughput and energy balanced reward function. Although our discussion is focused on 802.11ac networks, our method is readily applicable to other types of wireless networks.
... [7]), ii) transmit rate control (e.g. [8], [9]), or iii) a combination of the two as 'transmit power and rate control' ( [10], [11].) ...
... Values BW [kHz] [125,250,500] SF [#] [7,8,9,10,11,12] PS [B] [60, 230] SNR [dbm] [-40,-30,-20,-10,0] Our simulation results illustrate the relationship between LoRa transceiver's parameters and QoS metrics as well as applications requirements. The FCM clustering characterizes the impact of the parameters' selection on different QoS metrics. ...
... increases. This is because for a larger value of λ u , a platoon vehicle covers more nodes in its contention domain, which leads to a smaller channel access probability and thus a larger value of [20]. It can be seen that and as R c increases, E[D v 0 ,v N ] decreases exponentially. ...
A platoon of connected and automated vehicles (CAVs) is one of the promising autonomous-driving applications. Vehicles in a platoon need timely delivery of road-safety information in order to alter their speeds in time and thus maintain the stability of the platoon. The intra-platoon message delivery delay is a critical metric that has a big impact on the maintenance of a platoons stability. It depends on several system parameters, such as the number of vehicles in a platoon, the intra-platoon spacing, and the distribution of non-platoon vehicles. This paper studies the analysis of the intra-platoon message delivery delay in a platoon of CAVs moving on a highway road. A theoretical analytical model is derived to investigate the impacts of major system parameters on the intra-platoon message delivery delay. The derived analytical model considers a V2V hop-by-hop communication mode and takes into account the effects of both platoon and non-platoon vehicle nodes on channel access contention. The effect of hidden vehicle nodes is also considered. The derived analytical model is validated through simulation results and the impacts of major system parameters on the intra-platoon message delivery delay are investigated through numerical results. The derived analytical model can be used to provide reasonable reference values for system parameter setting in order to maintain the stability of an autonomous-driving platoon.
We consider the problem of energy efficiency aware dynamic adaptation of data transmission rate and transmission power of the users in carrier sensing based Wireless Local Area Networks (WLANs) in the presence of path loss, Rayleigh fading and log-normal shadowing. For a data packet transmission, we formulate an optimization problem, solve the problem, and propose a rate and transmission power adaptation scheme with a restriction methodology of data packet transmission for achieving the optimal energy efficiency. In the restriction methodology of data packet transmission, a user does not transmit a data packet if the instantaneous channel gain of the user is lower than a threshold. To evaluate the performance of the proposed scheme, we develop analytical models for computing the throughput and energy efficiency of WLANs under the proposed scheme considering a saturation traffic condition. We then validate the analytical models via simulation. We find that the proposed scheme provides better throughput and energy efficiency with acceptable throughput fairness if the restriction methodology of data packet transmission is included. By means of the analytical models and simulations, we demonstrate that the proposed scheme provides significantly higher throughput, energy efficiency and fairness index than a traditional non-adaptive scheme and an existing most relevant adaptive scheme. Throughput and energy efficiency gains obtained by the proposed scheme with respect to the existing adapting scheme are about 75% and 103%, respectively, for a fairness index of 0.8. We also study the effect of various system parameters on throughput and energy efficiency and provide various engineering insights.
Data rate management algorithms aim to perform a proper selection of the signal modulation and the coding rate to avoid the corruption of data bits. This paper describes a preliminary investigation on the bit corruption pattern related to the IEEE 802.11p standard. Measurements have been acquired with an experimental test-bed made up with a couple of software radios to perform white-box tests. Software radios are stationary and operate on the same channel without disturbances coming from concurrent communication. The aim of this experimental test-bed is to represent a static scenario where vehicles are stationary such as a crossroad situation. The data analysis shows that a data length reduction as an impact as much as a decrease of the data rate. A deeper analysis of the data bit corruption distribution highlights that some bits are more corrupted than others, rejecting the independent and identically distributed assumption for some situations. This opens a perspective to design algorithms dealing with multiple constraints, even if they are Open image in new window -complete.
Connected vehicles bring new challenges for communication technologies. Vehicles become capable of performing actions depending on wireless V2X communications (ex: automatic emergency braking, crossing paths with other vehicles, handling platooning situations). Despite being essential in the case of industrial deployments, cybersecurity also acts as a scientific lock to secure the system from its conception. Facing with the increasing number of cyberattacks, but also with the increasing of the attack surface of vehicles, the securing of V2X communications is necessary. However, all existing attacks cannot always be tested with proper hardware. The simulation software approach allows us to free ourselves from this constraint. In this paper, we investigate the security vulnerabilities of ITS-G5 (European DSRC) communications in the presence of outside attackers. We considered 4 attacks: jamming, replay, falsification and network congestion. We used VENTOS platform to execute the different scenarios and demonstrated with it that these attacks have a real impact on vehicle’s driving.
This paper provides an overview of the antenna integration problem with an illustration of antenna integration for the next generation railway communication systems. The influence of integration on the basic antenna parameters is detailed and the challenges and constraints for integration are discussed. State-of-the-art antenna integration schemes are summarised and a novel approach for antenna integration based on the use of metamaterial inclusions and intermodal coupling analysis is proposed.
In a mobile ad-hoc networks (MANET), one essential issue is medium access control (MAC) which addresses how to utilize the radio spectrum efficiently and to resolve potential contention and collision among mobile hosts on using the medium. Existing work is dedicated to using multiple channels and power control to improve the performance of MANET. We investigate the possibility of bringing the concepts of power control and multi-channel medium access together in the MAC design problem in a MANET. Existing protocols only address one of these issues independently. The proposed protocol is characterized by the following features: it follows an “on-demand” style to assign channels to mobile hosts; the number of channels required is independent of the network topology and degree; it flexibly adapts to host mobility; no form of clock synchronization is required; and power control is used to exploit frequency reuse. Power control may also extend battery life and reduce signal interference, both of which are important in wireless communication. Through simulations, we demonstrate the advantage of our new protocol
In this paper we present a simple but powerful dynamic link adaptation mechanism for wireless LANs that is compliant with the IEEE 802.11a standard. Using this method, a transmitter is able to estimate the current link quality and, based on this information, to adapt the transmission parameters, namely the transmission data rate or the transmission power level, dynamically. To determine the link quality, the transmitter employs only information that is available locally. Therefore, the proposed method can be implemented without changes or enhancements to the current IEEE 802.11 standard. The efficiency of our method is investigated and evaluated by means of simulations.
In this paper we present a simple but powerful dynamic link adaptation mechanism for wireless LANs, which are based on the IEEE 802.11a standard. Using this method, a transmitter is able to detect whether the quality of the link is improving or deteriorating, and based on this information to switch to a higher or lower transmission rate, respectively. For determining the link quality, the transmitter employs only information that is available locally. Therefore, the proposed method can be implemented without changes or enhancements to the current IEEE 802.11 standard. The efficiency of our method is investigated and evaluated by means of simulations.
IEEE 802.11 wireless local area network (WLAN) physical layers (PHYs) support multiple transmission rates. The PHY rate to be used for a particular frame transmission is solely determined by the transmitting station. The transmitting rate should be chosen in an adaptive manner since the wireless channel condition varies over time due to such factors as station mobility, time-varying interference, and location-dependent errors. In this paper, we present a novel link adaptation algorithm, which aims to improve the system throughput by adapting the transmission rate to the current link condition. Our algorithm is simply based on the received signal strength measured from the received frames, and hence it does not require any changes in the current IEEE 802.11 WLAN medium access control (MAC) protocol. Based on the simulation and its comparison with a numerical analysis, it is shown that the proposed algorithm closely approximates the ideal case with the perfect knowledge about the channel and receiver conditions.
In July 1997 the Institute of Electrical and Electronics Engineers (IEEE) completed standard 802.11 for wireless local area networks (LANs). WaveLAN®-II, to be released early in 1998, offers compatibility with the IEEE 802.11 standard for operation in the 2.4-GHz band. It is the successor to WaveLAN-I, which has been in the market since 1991. As a next-generation wireless LAN product, WaveLAN-II has many enhancements to improve performance in various areas. An IEEE 802.11 direct sequence spread spectrum (DSSS) product, WaveLAN-II supports the basic bit rates of 1 and 2 Mb/s, but it can also provide enhanced bit rates as high as 10 Mb/s. This paper discusses various aspects of the system design of WaveLAN-II and characteristics of its antenna, radio-frequency (RF) front-end, digital signal processor (DSP) transceiver chip, and medium access controller (MAC) chip.
In this paper, we explore MAC approaches that could provide increased throughput to 802.11 WLANs. First we analyze the throughput performance of 802.11 WLANs by deriving expressions for the maximum achievable throughput. Based on these results, we identify the main throughput-limiting factors and discuss approaches that may reduce their impact. We also propose a novel approach, called multiMAC, which allows a significant throughput increase without the need for new high-rate transmission modes. An important feature of our approach is its interoperability and compatibility with current 802.11 WLANs. Furthermore it is very simple, requires no hardware support, and can easily be implemented in software.
Transmit power control (TPC) has been recognized as one of the effective ways to save energy in wireless devices. In this paper, we demonstrate the energy-efficient distributed coordination functions (DCF) operation of IEEE 802.11a wireless LANs (WLANs) via TPC and physical layer (PHY) rate adaptation. The key idea is to enforce an RTS/CTS frame exchange before each data transmission, and then select the most energy-efficient combination of the PHY mode and the transmit power level for the subsequent data frame transmission to save energy. The performance of the proposed scheme is evaluated via simulation in the ns-2 simulator.