Browsing by Author "Da Silva Goncalves, Vinicius"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item PERFORM: A Platform for Experimental Research in WLAN with Focus on Real Network Traffic and Multi-User Channel Access(2020-04-21) Da Silva Goncalves, Vinicius; Knightly, Edward WMulti-user (MU) - MIMO and OFDMA - is the next revolution in WiFi. Many experimental platforms today can support the exploration of physical layer aspects of MU but cannot run real-time experiments integrated into end-to-end network systems. However, recent work has shown that real network traffic regimes can be equally important to the MU performance of a WLAN. In this thesis we present PERFORM, a novel experimental platform for implementation and evaluation of WLAN MAC policies. This platform is the first end-to-end integrated system that carries real-time network traffic and, at the same time, allows for the flexible prototyping and evaluation of advanced WLAN MAC policies, including MU-MIMO, OFDMA, triggered uplink access, buffer status report, and data-driven policies. We present the platform validation experiments and also show the application of PERFORM in two uplink MU-MIMO experiments to showcase its capabilities and the new research that it enables.Item Triggered Uplink MU-MIMO and Access Adaptation for 802.11 WLANs(2022-11-30) Da Silva Goncalves, Vinicius; Knightly, Edward WUplink Multi-User (MU) MIMO transmissions allow clients to simultaneously transmit independent data streams to the Access Point (AP), effectively multiplying the capacity of the wireless channel for uplink access. The IEEE 802.11ax amendment defines the Triggered Uplink Access (TUA) mechanism as the only way to initiate an uplink MU-MIMO transmission in Wi-Fi, which enables an AP to start and time synchronize simultaneous uplink MU transmissions by broadcasting a trigger frame containing the resource allocation information. Unfortunately, the aforementioned procedure introduces challenges in the design and implementation of medium access control policies for 802.11 wireless networks, including contention and scheduling problems. In this thesis we present the following three contributions. First, we design, implement, and validate PERFORM, a novel experimental platform for implementation and evaluation of WLAN MAC policies. This platform is the first end-to-end integrated system that carries real-time network traffic and, at the same time, allows for the flexible prototyping and evaluation of advanced WLAN MAC policies, including MU-MIMO, TUA, and buffer status reports. Second, we experimentally study the role of real application traffic on the performance of TUA. While TUA gains for fully backlogged traffic are well established, we show that bursty closed-loop traffic radically transforms performance. Last, we introduce Client-side Access Manipulation (CAM) as a mechanism that enables clients to dynamically adapt their channel access priority without explicitly coordinating state with the AP to realize an efficient uplink multi-user WLAN. Our results start by presenting the PERFORM platform validation, which verifies that the platform can achieve the necessary performance targets. Then, using PERFORM, we find that TUA significantly reduces file transfer latency compared to legacy single-user uplink, but unfortunately the standardized method for low-overhead backlog reporting leaves substantial benefits unrealized. Last, we show that CAM achieves gains in throughput and up to 65% reduction in average latency. Moreover, with the use of the standard’s defined access adaptation mechanism on the same scenarios, the aggregate throughput decreases, and the average latency increases sharply.