Wednesday, October 29, 2014

HotNets 2014: Crowdsourcing Access Network Spectrum Allocation Using Smartphones

Scribe notes by Athina Markopoulou.

Crowdsourcing Access Network Spectrum Allocation Using Smartphones

(presented by Jinghao Shi)

The main idea proposed in this paper was to use a smartphone “within proximity” of the primary device (laptop or tablet) to collect measurements (channel utilization and WiFi scan results) without disrupting the primary device. The key participants in the PocketSniffer system are: the phone, the laptop, the PocketSniffer AP, the PocketSniffer server. Challenges that need to be addressed include the following:
  • Physical proximity: use phone next to laptop to collect measurements on the laptop’s behalf.
  • Incentives for the phone: one way is to use the user’s  own phone to collect measurements for the user’s laptop. If Bob’s phone is used to help Alice’s laptop, credits can be offered to Bob, to use later in exchange for QoS.
  • Measurement efficiency: pick the phone to use based on criteria, such as proximity and battery level.
  • Measurement validation: the phone may provide wrong measurements (lazy, selfish).  Solution: trust the AP + cross validation.
The author also talked about the bigger picture (global information, cooperation, use of game theory, interaction of wifi-cellular) and their implementation on Nexus 5 and a public testbed.

Q&A  (During Panel Discussion, some of them addressed to all papers):
Q: How do you decide which phone, within proximity of the laptop, to use?
A: We can have this information and pick the closest one.
Followup Q: Using the closest phone to the laptop may not be the best proxy for measurements, due to fading. Locationsvery close to each other (exact distance depending on frequency/wavelength) may have very different signal strengths. Have you actually done measurements to validate that?
A: Yes, we pick the closer phone. Our measurements, so far, put the phone on top of the laptop. For the purposes of picking which channel to use this is good enough.

Q: Where do you envision the computation to happen?
A: Where to implement the algorithm (to decide what phone to use for measurement and what WiFi channel to use) must take into account security and privacy, concerns.  In enterprise environments, there is a centralized controller.

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