Improving the Performance and Efficiency of Wireless Networks Using Rate Adaptation - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Improving the Performance and Efficiency of Wireless Networks Using Rate Adaptation write by Muhammad Owais Khan. This book was released on 2015. Improving the Performance and Efficiency of Wireless Networks Using Rate Adaptation available in PDF, EPUB and Kindle. Recent years have seen a staggering increase in the deployment and utilization of wireless networks. More and more devices are being equipped with Wireless LAN (WLAN) cards to take advantage of the omnipresence of WLAN networks. Therefore, it has become necessary that the protocols used by WLANs are efficient and provide good performance. Rate Adaptation protocols are an important mechanism employed by WLANs to improve network performance. This dissertation develops three complementary techniques, which use rate adaptation to optimize and improve performance by i) performing rate adaptation to optimize energy consumption, ii) developing a more accurate technique to predict the frame delivery ratio that is used by rate adaptation protocols, and iii) jointly optimizing rate adaptation with data retransmission to maximize throughput. More specifically, in i), we use extensive measurements to develop a simple yet accurate energy consumption model for 802.11n wireless cards. We use the model 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 required in many existing rate adaptation schemes. In ii), we find that the accuracy of existing delivery ratio calculation techniques is still limited due to bursty errors inherent to the wireless channel. We develop a new method for computing packet delivery rate that captures the burstiness of errors. Furthermore, we propose a new data interleaving technique, which leverages our framework to reduce the burstiness of errors, thereby improving frame delivery ratio. Finally, in iii), we address the susceptibility of wireless networks to transmission failures due to dynamic channel conditions and unpredictable interference. To efficiently recover from failures, we propose a retransmission scheme where the receiver combines information received from multiple failed transmissions associated with the same frame. The protocol has two distinguishing features. First, it simultaneously supports partial retransmission and combines bits with low confidence. Second, it jointly optimizes the data rate of the retransmission and the information to be retransmitted to maximize throughput.
Improving the Performance of Wireless Networks Using Frame Aggregation and Rate Adaptation
Improving the Performance of Wireless Networks Using Frame Aggregation and Rate Adaptation - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Improving the Performance of Wireless Networks Using Frame Aggregation and Rate Adaptation write by Won Soo Kim. This book was released on 2010. Improving the Performance of Wireless Networks Using Frame Aggregation and Rate Adaptation available in PDF, EPUB and Kindle. As the data rates supported by the physical layer increase, overheads increasingly dominate the throughput of wireless networks. A promising approach for reducing overheads is to group a number of frames together into one transmission. This can reduce the impact of overheads by sharing headers and the time spent waiting to gain access to the transmission floor. Traditional aggregation schemes require that frames that are aggregated all be destined to the same receiver. These approaches neglect the fact that transmissions are broadcast and a single transmission will potentially be received by many receivers. Thus, by taking advantage of the broadcast nature of wireless transmissions, overheads can be amortized over more data and achieve more performance gain. To show this, we design a series of MAC-based aggregation protocols that take advantage of rate adaptation and the broadcast nature of wireless transmissions. We first show the design of a system that can aggregate both unicast and broadcast frames. Further, the system can classify TCP ACK segments so that they can be aggregated with TCP data flowing in the opposite direction. Second, we develop a rate-adaptive frame aggregation scheme that allows us to find the best aggregation size by tracking the size based on received data frames and the data rate chosen by rate adaptation. Third, we develop a multi-destination frame aggregation scheme to aggregate broadcast frames and unicast frames that are destined for different receivers using delayed ACKs. Using a delayed ACK scheme allows multiple receivers to control transmission time of the ACKs. Finally, we extend multi-destination rate-adaptive frame aggregation to allow piggybacking of various types of metadata with user packets. This promises to lower the impact of metadata-based control protocols on data transport. A novel aspect of our work is that we implement and validate the designs not through simulation, but rather using our wireless node prototype, Hydra, which supports a high performance PHY based on 802.11n. To validate our designs, we conduct extensive experiments both on real and emulator-based channels and measure system performance.
Improving Wireless Network Performance Using Sensor Hints
Improving Wireless Network Performance Using Sensor Hints - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Improving Wireless Network Performance Using Sensor Hints write by Lenin Ravindranath Sivalingam. This book was released on 2010. Improving Wireless Network Performance Using Sensor Hints available in PDF, EPUB and Kindle. Users of wireless devices often switch between being stationary and in motion while transferring data. Protocols that perform well in the static setting (where the channel conditions are relatively stable), however, tend to perform poorly when in motion (where channel conditions change rapidly), and vice versa. To circumvent this problem, we note that commodity smartphones and tablet devices come equipped with a variety of sensors, including accelerometers, multiple positioning sensors, magnetic compasses, and inertial sensors (gyros) that can provide hints about the device's mobility. In this thesis, we posit that these sensors can be profitably used to improve the performance of wireless network protocols running on these mobile devices and introduce an architecture for using external sensor hints for this purpose. We validate this idea with many different wireless protocols. First, we show how access points can perform better rate adaptation by changing strategies when they receive hints about a client's mobility. Second, we show how probing protocols for topology maintenance in mesh networks can increase both their efficiency and accuracy by adaptively probing based on movement. Third, we show how vehicular mesh networks can use directionality hints to improve the connectivity of routes. Finally, we outline several other novel applications of external sensor hints for improving wireless network performance. We evaluate our protocols using trace-driven simulation and real-world experiments. We show that our hint-aware rate adaptation protocol increases throughput by 30% to 50% on average over frame-based and SNR-based protocols. Our hint-aware probing protocol reduces the bandwidth consumed by probing to accurately estimate link delivery probabilities-by a factor of 20 in our experiments. And, our hint-aware route selection in vehicular mesh networks increases route stability by a factor of 4 to 5 compared to a hint-free approach in our simulations.
Efficient Rate Adaptation in IEEE 802.11 Wireless Networks
Efficient Rate Adaptation in IEEE 802.11 Wireless Networks - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Efficient Rate Adaptation in IEEE 802.11 Wireless Networks write by Anne N. Ngugi. This book was released on 2008. Efficient Rate Adaptation in IEEE 802.11 Wireless Networks available in PDF, EPUB and Kindle.
Improving the Performance of Wireless LANs
Improving the Performance of Wireless LANs - read free eBook in online reader or directly download on the web page. Select files or add your book in reader. Download and read online ebook Improving the Performance of Wireless LANs write by Nurul Sarkar. This book was released on 2014-01-08. Improving the Performance of Wireless LANs available in PDF, EPUB and Kindle. While there are countless books on wireless networks, few actually quantify the key performance-limiting factors of wireless local area networks (WLANs) and describe various methods for improving WLAN performance. Fulfilling these needs, Improving the Performance of Wireless LANs: A Practical Guide provides both theoretical background and empirical
