Results 1 - 10
of
32
802.11ec: Collision Avoidance without Control Messages ∗
"... In this paper, we design, implement and evaluate 802.11ec (Encoded Control), an 802.11-based protocol without control messages: instead, 802.11ec employs correlatable symbol sequences, which together with the timing the codes are transmitted, encode all control information and change the fundamental ..."
Abstract
-
Cited by 8 (0 self)
- Add to MetaCart
(Show Context)
In this paper, we design, implement and evaluate 802.11ec (Encoded Control), an 802.11-based protocol without control messages: instead, 802.11ec employs correlatable symbol sequences, which together with the timing the codes are transmitted, encode all control information and change the fundamental design properties of the MAC. The use of correlatable symbol sequences provides two key advantages: (i) efficiency, as it permits a near order of magnitude reduction of the control time; (ii) robustness, because codes are short and easily detectable even at low SINR and even while a neighbor is transmitting data. We implement 802.11ec on an FPGA-based software defined radio. We perform a large number of experiments and show that, compared to 802.11 (with and without RTS/CTS), 802.11ec achieves a vast efficiency gain in conveying control information and resolves key throughput and fairness problems in the presence of hidden terminals, asymmetric topologies, and general multi-hop topologies.
Online energy consumption monitoring of wireless testbed infrastructure through the NITOS EMF framework
- in Proceedings of the 8th ACM International Workshop on Wireless Network Testbeds, Experimental Evaluation and Characterization, WiNTECH ’13
, 2013
"... Development of energy-efficient protocols and algorithms re-quires in-depth understanding of the power consumption characteristics of real world devices. To this aim, energy efficiency analysis is performed by the research community, mainly focusing on the development of power consumption models. Ho ..."
Abstract
-
Cited by 3 (2 self)
- Add to MetaCart
(Show Context)
Development of energy-efficient protocols and algorithms re-quires in-depth understanding of the power consumption characteristics of real world devices. To this aim, energy efficiency analysis is performed by the research community, mainly focusing on the development of power consumption models. However, recent studies [1] have highlighted the inability of existing models to accurately estimate energy consumption even in non-composite scenarios, where the operation of a single device is analyzed. The inability of such models is further highlighted under real life scenarios, where the impact induced by the simultaneous operation of several devices renders the application of traditional models completely inappropriate. As a result, energy efficiency eval-uation under complex configurations and topologies, needs to be experimentally investigated through the application of online monitoring solutions. In this work, we propose the innovative NITOS Energy consumption Monitoring Frame-work (EMF) able to support online monitoring of energy ex-penditure, along with the experiment execution. The devel-oped framework is built on a distributed network of low-cost, but highly accurate devices and is fully integrated with the large-scale wireless NITOS testbed. Framework evaluation is performed under both low-level experiments that demon-strate the platform’s high-level accuracy, as well as through high-level experiments that showcase how online and dis-tributed monitoring can facilitate energy performance as-sessment of realistic testbed experiments.
SloMo: Downclocking WiFi Communication
"... As manufacturers continue to improve the energy efficiency of battery-powered wireless devices, WiFi has become one of—if not the—most significant power draws. Hence, modern devices fastidiously manage their radios, shifting into low-power listening or sleep states whenever possible. The fundamental ..."
Abstract
-
Cited by 3 (1 self)
- Add to MetaCart
(Show Context)
As manufacturers continue to improve the energy efficiency of battery-powered wireless devices, WiFi has become one of—if not the—most significant power draws. Hence, modern devices fastidiously manage their radios, shifting into low-power listening or sleep states whenever possible. The fundamental limitation with this approach, however, is that the radio is incapable of transmitting or receiving unless it is fully powered. Unfortunately, applications found on today’s wireless devices often require frequent access to the channel. We observe, however, that many of these same applications have relatively low bandwidth requirements. Leveraging the inherent sparsity in Direct Sequence Spread Spectrum (DSSS) modulation, we propose a transceiver design based on compressive sensing that allows WiFi devices to operate their radios at lower clock rates when receiving and transmitting at low bit rates, thus consuming less power. We have implemented our 802.11b-based design in a software radio platform, and show that it seamlessly interacts with existing WiFi deployments. Our prototype remains fully functional when the clock rate is reduced by a factor of five, potentially reducing power consumption by over 30%. 1
1Code-Based Neighbor Discovery Protocols In Mobile Wireless Networks
"... Abstract—In mobile wireless networks, the emerging proximity-based applications have led to the need for highly effective and energy-efficient neighbor discovery protocols. However, existing works cannot realize the optimal worst-case latency in symmetric case, and their performances with asymmetric ..."
Abstract
-
Cited by 2 (0 self)
- Add to MetaCart
(Show Context)
Abstract—In mobile wireless networks, the emerging proximity-based applications have led to the need for highly effective and energy-efficient neighbor discovery protocols. However, existing works cannot realize the optimal worst-case latency in symmetric case, and their performances with asymmetric duty cycles can still be improved. In this work, we investigate asynchronous neighbor discovery through a code-based approach, including the symmetric and asymmetric cases. We derive the tight worst-case latency bound in the case of symmetric duty cycle. We design a novel class of symmetric patterns called Diff-Codes, which is optimal when the Diff-Code can be extended from a perfect difference set. We further consider the asymmetric case, and design ADiff-Codes. To evaluate (A)Diff-Codes, we conduct both simulations and testbed experiments. Both simulation and experiment results show that (A)Diff-Codes significantly outperform existing neighbor discovery protocols in both the median case and worst-case. Specifically, in the symmetric case, the maximum worst-case improvement is up to 50%; in both symmetric and asymmetric cases, the median case gain is as high as 30%.
1An Energy Efficient MAC Protocol for Fully Connected Wireless Ad Hoc Networks
"... Abstract—Energy efficiency is an important performance mea-sure of wireless network protocols, especially for battery-powered mobile devices such as smartphones. This paper presents a new energy-efficient medium access control (MAC) scheme for fully connected wireless ad hoc networks. The proposed s ..."
Abstract
-
Cited by 2 (1 self)
- Add to MetaCart
(Show Context)
Abstract—Energy efficiency is an important performance mea-sure of wireless network protocols, especially for battery-powered mobile devices such as smartphones. This paper presents a new energy-efficient medium access control (MAC) scheme for fully connected wireless ad hoc networks. The proposed scheme reduces energy consumption by putting radio interfaces in the sleep state periodically and by reducing transmission collisions, which results in high throughput and low packet transmission delay. The proposed MAC scheme can also address the energy saving in realtime traffics which require very low packet trans-mission delay. An analytical model is established to evaluate the performance of the proposed MAC scheme. Analytical and simulation results demonstrate that the proposed scheme has a significantly lower power consumption, achieves substantially higher throughput, and has lower packet transmission delay in comparison with existing power saving MAC protocols. Index Terms—Medium access control, wireless ad hoc net-works, energy efficiency, throughput, delay. I.
Recitation: Rehearsing wireless packet reception in software
- In Proceedings of the 21th Annual International Conference on Mobile Computing and Networking, Mobicom ’15
, 2015
"... This paper presents Recitation, the first software system that uses lightweight channel state information (CSI) to accurately predict error-prone bit positions in a packet so that applications atop the wireless physical layer may take the best action during subsequent transmissions. Our key insight ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
This paper presents Recitation, the first software system that uses lightweight channel state information (CSI) to accurately predict error-prone bit positions in a packet so that applications atop the wireless physical layer may take the best action during subsequent transmissions. Our key insight is that althoughWi-Fi wireless phys-ical layer operations are complex, they are deterministic. This en-ables us to rehearse physical-layer operations on packet bits before they are transmitted. Based on this rehearsal, we calculate a hidden parameter in the decoding process, called error event probability (EVP). EVP captures fine-grained information about the receiver’s convolutional or LDPC decoder, allowing Recitation to derive pre-cise information about the likely fate of every bit in subsequent packets, without any wireless channel training. Recitation is the first system of its kind that is both software-implementable and compatible with the existing 802.11 architecture for both SISO and MIMO settings. We experiment with commodity Atheros 9580Wi-Fi NICs to demonstrate Recitation’s utility with three representative applications in static, mobile, and interference-dominated scenar-ios. We show that Recitation achieves 33.8 % and 16 % average throughput gains for bit-rate adaptation and partial packet recov-ery, respectively, and 6 dB PSNR quality improvement for unequal error protection-based video.
Exploiting ZigBee in Reducing WiFi Power Consumption for Mobile Devices
, 2013
"... Abstract—We present HoWiES, a system that saves energy consumed by WiFi interfaces in mobile devices with the assistance of ZigBee radios. The core component of HoWiES is a WiFi-ZigBee message delivery scheme that enables WiFi radios to convey different messages to ZigBee radios in mobile devices. B ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
Abstract—We present HoWiES, a system that saves energy consumed by WiFi interfaces in mobile devices with the assistance of ZigBee radios. The core component of HoWiES is a WiFi-ZigBee message delivery scheme that enables WiFi radios to convey different messages to ZigBee radios in mobile devices. Based on the WiFi-ZigBee message delivery scheme, we design three protocols that target three WiFi energy saving opportunities in scanning, standby and wakeup respectively. We have implemented the HoWiES system with two mobile devices platforms and two AP platforms. Our real-world experimental evaluation shows that our system can convey thousands of different messages fromWiFi radios to ZigBee radios with an accuracy over 98 percent, and our energy saving protocols, while maintaining the comparable wakeup delay to that of the standard 802.11 power save mode, save 88 and 85 percent of energy consumed in scanning state and standby state respectively. Index Terms—WiFi, 802.11, energy savings, ZigBee, 802.15.4, mobile devices Ç 1
Enfold: Downclocking OFDM in WiFi
"... Dynamic voltage and frequency scaling (DVFS) has long been used as a technique to save power in a variety of computing domains but typically not in communications devices. A fundamental limit that prevents decreasing the clock frequency is the Nyquist(-Shannon) sampling theorem, which states that th ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
Dynamic voltage and frequency scaling (DVFS) has long been used as a technique to save power in a variety of computing domains but typically not in communications devices. A fundamental limit that prevents decreasing the clock frequency is the Nyquist(-Shannon) sampling theorem, which states that the sampling rate must be twice the signal bandwidth. Recently, researchers have leveraged compressive sensing to demonstrate the possibility of decoding a sparse signal below Nyquist rate. In this work, we dramatically ex-tend the state of the art by showing how to decode non-sparse sig-nals, in particular, OFDM systems at sub-Nyquist rates. We exploit the aliasing that results from under-sampling and observe that there exists well-defined structure in terms of how OFDM signals are “folded up ” under aliasing. Based on our observations, we present Enfold, which allows existing WiFi chipsets to decode standards-compliant WiFi frames while operating at 50 % and 25 % of their rated clock rate. Our design is able to attain greater than 96 % and 83 % raw packet reception rates for moderate SNR while reducing the clock rate by 2 × and 4×, respectively. Moreover, our approach can be easily applied to other communication systems based on OFDM modulation. When evaluated on popular smartphone app traces, Enfold reduces energy consumption by up to 34%.
Model-Driven Energy-Aware Rate Adaptation
"... Rate adaptation in WiFi networks has received significant attention recently. However, most existing work focuses on selecting the rate to maximize throughput. How to select a data rate to minimize energy consumption is an important yet under-explored topic. This problem is becoming increasingly imp ..."
Abstract
-
Cited by 1 (0 self)
- Add to MetaCart
(Show Context)
Rate adaptation in WiFi networks has received significant attention recently. However, most existing work focuses on selecting the rate to maximize throughput. How to select a data rate to minimize energy consumption is an important yet under-explored topic. This problem is becoming increasingly important with the rapidly increasing popularity of MIMO deployment, because MIMO offers diverse rate choices (e.g., the number of antennas, the number of streams, modulation, and FEC coding) and selecting the appropriate rate has significant impact on power consumption. In this paper, we first use extensive measurement to develop a simple yet accurate energy model for 802.11n wireless cards. Then we use the models to drive the design of an energy-aware rate adaptation scheme. A major benefit of a model-based rate adaptation is that applying a model allows us to eliminate frequent probes in many existing rate adaptation schemes so that it can quickly converge to the appropriate data rate. We demonstrate the effectiveness of our approach using trace-driven simulation and real implementation in a wireless testbed.
NITOS Energy Monitoring Framework: Real time Power Monitoring in Experimental Wireless Network Deployments
"... Development of energy-ecient protocols and algorithms re-quires in-depth understanding of the power consumption characteristics of real world devices. To this aim, energy eciency analysis is performed by the research community, mainly focusing on the development of power consumption models. However, ..."
Abstract
- Add to MetaCart
(Show Context)
Development of energy-ecient protocols and algorithms re-quires in-depth understanding of the power consumption characteristics of real world devices. To this aim, energy eciency analysis is performed by the research community, mainly focusing on the development of power consumption models. However, recent studies [1] have highlighted the inability of existing models to accurately estimate energy consumption even in non-composite scenarios, where the operation of a single device is analyzed. The inability of such models is further highlighted under real life scenar-ios, where the impact induced by the simultaneous opera-tion of several devices renders the application of traditional models completely inappropriate. As a result, energy e-ciency evaluation under complex configurations and topolo-gies, needs to be experimentally investigated through the application of online monitoring solutions. In this work, we propose the innovative NITOS Energy consumption Moni-toring Framework (EMF) able to support online monitoring of energy expenditure, along with the experiment execution. The developed framework is built on a distributed network of low-cost, but highly accurate devices and is fully inte-grated with the large-scale wireless NITOS testbed. The framework evaluation is performed under both low-level ex-periments that demonstrate the platform’s high-level accu-racy, as well as through high-level experiments that showcase how online and distributed monitoring can facilitate energy performance assessment of realistic testbed experiments. 1.
