| 題目：Toward Customizable Wi-Fi 主講人：李奇育教授國立交通大學資工系 時間：105年10月21日(星期五13：30 - 15：00) 地點：三峽校區社科院社1F04教室 Abstract: As the Wi-Fi technology becomes pervasive in reality, its usage pattern is also turning highly diversified in operation settings and application scenarios. This consequently leads to new design requirements for Wi-Fi networking solutions in terms of various combinations in energy efficiency and latency, in addition to the throughput. However, the state-of-the-art solutions typically chase for high speed in the different generations of Wi-Fi technologies (from 802.11a/g to 802.11n/ac) at the cost of other metrics. For example, Multiple-Input Multiple-Output (MIMO) is widely used to boost speed, yet it consumes much more power. Higher throughput may yield long-tail loss behaviors and compromise the perceived latency for data transfer. Fundamentally, we believe that both the user demand pull and the technology push call for customizable Wi-Fi solutions. In this talk, I will present our effort on customizable Wi-Fi technology. We propose solutions that seek to meet the diverse requirements (i.e., energy, throughput, and latency). Specifically, we have come up with technical results on two topics. The first one explores to use rate adaptation (RA), the mechanism critical to performance yet unspecified by the 802.11 standards, for energy efficiency. It is shown that current MIMO RA algorithms in 802.11n/ac are not energy efficient despite ensuring high throughput. Marginal throughput gain is achieved at much higher energy cost. We then propose EERA, an energy-efficient RA solution. It balances throughput for energy savings while meeting the data rate quest by applications. In the second topic, we target home Wi-Fi scenario and interactive gaming applications. We examine the millisecond-level latency requirements of such applications. We show that current solutions work well for throughput but not for latency, due to the long tail of the packet delay distribution. We thus propose LLRA, a new latency-aware RA scheme that reduces the tail latency. It takes concerted design in rate control, frame aggregation scheduling and software/hardware retransmission dispatching. The implementation and evaluation confirm the viability of both EERA and LLRA. In these two concrete designs, we confirm that, the upcoming Wi-Fi technology has to be customized to the given usage scenario and designated goals, and this involves complex tradeoffs along multiple performance metrics of throughput, latency and energy saving and along various granularities of data flows, flow aggregates, and devices within a single user client and among multiple users. Bio: Chi-Yu Li is currently an Assistant Professor with the Department of Computer Science, National Chiao Tung University (NCTU). He received the PhD degree in computer science from University of California, Los Angeles (UCLA) in 2015. Before joining UCLA, he received his Master’s and Bachelor’s degrees from the Department of Computer Science, NCTU. His research interests include wireless networking, mobile networks and systems, and network security. He has published several papers in top-tier academic conferences of both networking and security areas, such as ACM MOBICOM, IEEE INFOCOM, and ACM CCS. |
