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Wireless multicarrier communication systems transmit data by spreading it over multiple subcarriers and are widely used today owing to their robustness to multipath fading, high spectrum efficiency, and ease of implementation. In this paper, we use real measurements to show there is significant frequency diversity in Wi-Fi channels, and propose a series of(More)
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(More)
We consider the problem of tracking physical browsing by users in indoor spaces such as retail stores. Analogous to online browsing, where users choose to go to certain webpages, dwell on a subset of pages of interest to them, and click on links of interest while ignoring others, we can draw parallels in the physical setting, where a user might <i>walk</i>(More)
Localization is a fundamental operation for many wireless networks. While GPS is widely used for location determination, it is unavailable in many environments either due to its high cost or the lack of line of sight to the satellites (<i>e.g</i>., indoors, under the ground, or in a downtown canyon). The limitations of GPS have motivated researchers to(More)
The explosive growth of cellular traffic and its highly dynamic nature often make it increasingly expensive for a cellular service provider to provision enough cellular resources to support the peak traffic demands. In this paper, we propose iDEAL, a novel auction-based incentive framework that allows a cellular service provider to leverage resources from(More)
Wireless spectrum is a precious resource and must be allocated and used efficiently. Conventional spectrum allocations let a government agency e.g., FCC sell a portion of spectrum to one provider. This is not only restrictive, but also limits spectrum reuse and may lead to significant under-utilization of spectrum. In this paper, we develop a novel truthful(More)
The large body of research on localization has been driven by the goal of providing users with location-based services, be it mapping and navigation or local alerts and advertisements. However, as we discuss in this paper, location information can over time provide deep insight about about a user, going well beyond the location domain itself. We argue that(More)
In the recent years, the computing power of mobile devices has increased tremendously, a trend that is expected to continue in the future. With high-quality onboard cameras, these devices are capable of collecting large volumes of visual information. Motivated by the observation that processing this video on the mobile device can enable many new(More)
The explosive growth of cellular traffic and its highly dynamic nature often make it prohibitive or even infeasible for a cellular service provider to provision enough cellular resources to support the peak traffic demands. The current best practice is to have the cellular service provider deploy alternative wireless technologies, such as Wi-Fi and(More)
This paper proposes VideoFountain, a novel service that deploys kiosks at popular venues to store and transmit digital media to users' personal devices using Wi-Fi access points, which may not have Internet connectivity. We leverage mobile users to deliver content to these kiosks. A key component in this design is an in-depth understanding of user mobility.(More)