From 42872f771f96aeea90f736e6998d3fc4ae9bb402 Mon Sep 17 00:00:00 2001 From: Geoffrey Challen Date: Mon, 1 Jun 2015 17:09:08 -0400 Subject: [PATCH] Intro. --- abstract.tex | 14 +++++++------- introduction.tex | 99 ++++++++++++++++++++++++++++++++++++++++++++++++--------------------------------------------------- investigation.tex | 39 +++++++++++++++++++-------------------- 3 files changed, 74 insertions(+), 78 deletions(-) diff --git a/abstract.tex b/abstract.tex index 74e2370..7092cec 100644 --- a/abstract.tex +++ b/abstract.tex @@ -20,12 +20,12 @@ existing human relationships and can be maintained without elaborate reputation mechanisms. - To evaluate the effectiveness of reciprocal \wifi{} sharing, we analyze - 21~M \wifi{} scans collected from 254~smartphones over 5~months. Our - results show that even in a sparsely-populated suburban area, reciprocal - \wifi{} sharing is needed. And surprisingly, several reciprocal \wifi{} - sharing opportunities exist even among our extremely-small sample of users. - Motivated by these results, we present the design of \wisefi{}, a system - enabling reciprocal \wifi{} sharing. + To evaluate the potential for reciprocal \wifi{} sharing, we analyze 21~M + \wifi{} scans collected from 254~smartphones over 5~months. Our results + show that even in a sparsely-populated suburban area, reciprocal \wifi{} + sharing can be beneficial. And surprisingly, we detected several reciprocal + \wifi{} sharing opportunities even within our tiny user sample. Motivated + by these results, we present the design of \wisefi{}, a system enabling + reciprocal \wifi{} sharing. \end{abstract} diff --git a/introduction.tex b/introduction.tex index f26ecf3..e566158 100644 --- a/introduction.tex +++ b/introduction.tex @@ -14,7 +14,10 @@ other nearby private home APs. \begin{figure}[t] % - \includegraphics[width=\columnwidth]{./figures/motivation.pdf} + \centering + \includegraphics[width=0.9\columnwidth]{./figures/motivation.pdf} + % + %\vspace*{-0.1in} % \caption{\textbf{Example of Reciprocal \wifi{} Sharing.} Solid arrows represent weak connections, while dashed lines represent strong @@ -22,60 +25,54 @@ other nearby private home APs. % \label{fig:motivation} % + \vspace*{-0.1in} \end{figure} Unfortunately, uncoordinated deployment of overlapping private networks can create interference that degrades performance, which may then cause users to -respond in ways that further exacerbate the problem. Consider Alice and Bob's -neighboring apartments shown in Figure~\ref{fig:motivation}. Alice has -deployed her AP in her living room, while Bob has deployed his in his -bedroom. Due to the proximity of their apartments, Alice receives a stronger -signal from Bob's router when she is in her bedroom. But because she cannot -connect to Bob's router, she must either use the lower-bandwidth connection -to her existing AP or deploy an additional AP in her bedroom. Both of these -options generate additional wireless interference for her neighbors, -including Bob. And while we have used Alice as an example, Bob also faces the -same poor choice. - -However, due to factors such as blockage or fading in wireless signal -propagation, home \wifi{} AP usually does not provide equally satisfying \wifi{} -coverage at all places within the house. Instead, it is likely that the user -receives better \wifi{} signal from a neighbor's AP at certain spots. For -instance, consider Alice and Bob who live in neighbor apartments, as shown in -Figure~\ref{fig:motivation}, each of them receives a stronger \wifi{} signal -from the other's home AP than their own at certain places within their -apartments, revealing a \textit{reciprocal} \wifi{} sharing opportunity where -both parties can improve their \wifi{} performance by allowing each other to -access their own private networks. - -Compared to traditional community networks such as FON~\cite{fon} or -OpenWireless~\cite{openwireless}, such reciprocal sharing opportunity has -several unique properties that make it interesting to explore. First, such -opportunity is usually \textit{immediate} between two physically colocated -parties, such as two neighbors. This helps relief the concerns of sharing -network to random strangers in traditional community networks and makes it more -practical to establish the sharing. Second, bonding to physical colocation -relationship makes the opportunity \textit{stable} over time, enabling -asynchronous fair sharing over longer period of time. +respond in ways that further exacerbate the problem. Consider Alice's/Bob's +apartment shown in Figure~\ref{fig:motivation}. Alice/Bob has deployed +her/his AP in her/his living room/bedroom. Due to the proximity of their +apartments, Alice/Bob receives a stronger signal from Bob's/Alice's router +when she/he is in her/his bedroom/living room. But because Alice/Bob cannot +connect to Bob's/Alice's router, she/he must either use the lower-bandwidth +connection to her/his existing AP or deploy an additional AP in her/his +bedroom/living room. Both options generate additional wireless interference +for her/his neighbors, including Bob/Alice. +Ideally, Alice/Bob would allow Bob/Alice to use her/his router. Obviously +this solution requires less hardware. But it also improves performance while +reducing interference and client energy consumption, both by allowing the APs +to coordinate overlapping transmissions and by allowing clients to achieve +higher bitrates at lower transmission powers. We refer to this +mutually-beneficial arrangement as \textit{reciprocal \wifi{} sharing}. -Nevertheless, there are several challenges in fulfilling the vision of -reciprocal \wifi{} sharing shown in Figure~\ref{fig:motivation}. First, although -the motivating example is inspired by the authors' own experience, it is not -clear how often such opportunity exists for broader range of users in real life -scenarios. Second, suppose the sharing opportunity does exist and is detected, -there is no systematic solutions to enable the \wifi{} sharing without -compromising the security and privacy of user's home network. Finally, after the -\wifi{} sharing is established, it is challenging to ensure that the -relationship remains reciprocal for both parties. +Reciprocal \wifi{} sharing has benefits compared to attempts to use private +APs to establish community networks such as FON~\cite{fon} or +OpenWireless~\cite{openwireless}. Reciprocal \wifi{} sharing opportunities +are more likely to align with existing human relationships, such as this +example involving two neighbors, rather than requiring users to open their +private networks to strangers. And because reciprocal \wifi{} sharing +involves only pairwise cooperation, agreements can be established and +monitored without the elaborate reputation systems or credit mechanisms +required to prevent freeloading in large communities. Once Alice notices that +the sharing agreement with Bob is no longer beneficial---either because she +no longer needs his connection or because he is degrading her service to the +point where it is no longer useful---she can immediately terminate it. -To address these challenges, we first present extensive analysis of the -\PhoneLab{} \wifi{} dataset which contains \num{21192417} scan results from 254 -smartphones over 5 months (Section~\ref{sec:investigation}). The results show -that such reciprocal \wifi{} sharing opportunities does exists even in a spatial -sparse dataset. Inspired by the results, we present the design of \wisefi{} -(Section~\ref{sec:design}), a system that detects such reciprocal \wifi{} -sharing opportunities using smartphones, enables \wifi{} sharing on APs with or -without guest network support, and ensures the sharing remain reciprocal. -Finally, we discuss some open challenges in implementing such a system and point -directions for future works (Section~\ref{sec:challenges}). +But how often is reciprocal \wifi{} sharing beneficial and possible in +practice? To explore these questions, we begin in +Section~\ref{sec:investigation} by analyzing a dataset collected on the +\PhoneLab{}~smartphone testbed containing \num{21192417} \wifi{} scan results +from 254~smartphones over 5~months (\S~\ref{sec:investigation}). Despite the +fact that the geographic extent of the dataset is suburban Buffalo, which as +a city has a population density an order of magnitude lower than +densely-populated areas like Manhattan, we still find that many users would +benefit from being able to connect to neighboring private networks. Even more +surprisingly, despite monitoring only several hundred users we were still +able to identify several reciprocal \wifi{} sharing opportunities in our tiny +sample. Motivated by these results Section~\ref{sec:design} presents the +design of \wisefi{}, a system addressing the practical challenges of +establishing and monitoring reciprocal \wifi{} sharing agreements. We +conclude by identifying some open challenges in implementing such a system as +future work in Section~\ref{sec:challenges}. diff --git a/investigation.tex b/investigation.tex index edc72ea..0987c22 100644 --- a/investigation.tex +++ b/investigation.tex @@ -2,12 +2,12 @@ \label{sec:investigation} To investigate reciprocal sharing opportunity in real life scenarios, we -obtained a \wifi{} scan result dataset from \PhoneLab{} -(\S\ref{subsec:phonelab}). We first discuss some heuristics to identify the home -AP for each device (\S\ref{subsec:homeap}). Then we show the RSSI comparison -between a user's home and neighbor APs (\S\ref{subsec:better}). Finally, we -explore the reciprocal sharing relationships in the dataset -(\S\ref{subsec:reciprocal}). +obtained a \wifi{} scan result dataset from +\PhoneLab{}\footnote{\url{http://www.phone-lab.org}} (\S\ref{subsec:phonelab}). +We first discuss some heuristics to identify the home AP for each device +(\S\ref{subsec:homeap}). Then we show the RSSI comparison between a user's +home and neighbor APs (\S\ref{subsec:better}). Finally, we explore the +reciprocal sharing relationships in the dataset (\S\ref{subsec:reciprocal}). \subsection{PhoneLab \wifi{} Dataset} \label{subsec:phonelab} @@ -31,20 +31,19 @@ explore the reciprocal sharing relationships in the dataset \label{tab:summary} \end{table} -\PhoneLab{}\cite{phonelab-sensemine13} is a public smartphone platform testbed -operated at the University at Buffalo. Several hundreds of participants carry -instrumented Nexus 5 smartphones as their primary device. In particular, the -smartphone platform was modified to log each \wifi{} scan result and \wifi{} -connection events naturally generated by the Android system. Note that from data -collection point of view, platform instrumentation is not necessary, and the -same information can also be logged by applications with appropriate -permissions. Table~\ref{tab:summary} summarizes the \PhoneLab{} \wifi{} dataset. - -A \wifi{} scan result represents the device's network visibility, and consists -of multiple entries---each corresponds to one \wifi{} AP the device observed. -The content of one entry includes: (1) beacon timestamp, (2) AP SSID and BSSID, -(3) AP channel and (4) RSSI. Additionally, the timestamp when the scan was -performed is also logged. +\PhoneLab{}\cite{phonelab-sensemine13} is a public smartphone platform +testbed operated at the University at Buffalo. Several hundreds of +participants carry instrumented Nexus 5 smartphones as their primary device. +In particular, the smartphone platform was modified to log each \wifi{} scan +result and \wifi{} connection events naturally generated by the Android +system. Note that from data collection point of view, platform +instrumentation is not necessary, and the same information can also be logged +by applications with appropriate permissions. A \wifi{} scan result +represents the device's network visibility, and consists of multiple +entries---each corresponds to one \wifi{} AP the device observed. The content +of one entry includes: (1) beacon timestamp, (2) AP SSID and BSSID, (3) AP +channel and (4) RSSI. The timestamp when the scan was performed is also +logged. Table~\ref{tab:summary} summarizes the \PhoneLab{} \wifi{} dataset. \subsection{Home AP Detection} \label{subsec:homeap} -- libgit2 0.22.2