Abstract—Wireless Community Networks (WCNs) are wide-area wireless networks whose nodes are owned and managed by volunteers. We focus on the provision of free Internet access to mobile users through WCN-controlled wireless LAN access points (APs). We rely on reciprocity: a person participates in the WCN and provides free Internet access to mobile users in order to enjoy the same benefit when mobile. Our reciprocity scheme is compatible with the distinctive structure of WCNs: it does not require registration with authorities, relying only on uncertified free identities (public-private key pairs). Users sign digital receipts when they consume service. The receipts form a receipt graph, which is used as input to a reciprocity algorithm that identifies contributing users using network flow techniques. Simulations show that this algorithm can sustain reciprocal cooperation. We have implemented our algorithm to run on common WCN equipment, namely the Linksys WRT54GS AP. I.

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Abstract—In densely populated cities, Wi-Fi networks—private or otherwise—are ubiquitous. We focus on the provision of citywide broadband communication capability to mobile users through private Wi-Fi networks that are in range but belong to others. We form a club that relies on indirect reciprocity: Members participate in the club and provide free Wi-Fi access to other members in order to enjoy the same benefit when they are away from their own Wi-Fi network. Our club scheme does not require registration with an authority and does not rely on centrally issued club identities: Members create their own identities (public-private key pairs) and receive signed digital receipts when they provide Wi-Fi service to other members. These receipts form a distributed receipt graph, parts of which are used as input to an indirect reciprocity algorithm that classifies club members according to their contribution. We show that our algorithm can sustain cooperation within the club and is robust to attacks by free-riders. We implement and evaluate our proposed club algorithms on commodity Wi-Fi routers and dual-mode cellular/Wi-Fi phones. Because we anticipate that Wi-Fi telephony will be a popular club application, we present and evaluate a secure and decentralized architecture for citywide voice (and multimedia) communications that is compatible with our club both from an architectural as well as an incentives perspective.

Abstract—Wireless Community Networks (WCNs) are metropolitan-area networks whose nodes are owned and managed by volunteers. These networks can be used to build large scale public infrastructures for providing ubiquitous high-speed wireless broadband access through the private contributions of individual community members who use their hotspots to forward foreign traffic from and to nearby lowmobility clients. We have designed and developed a prototype aggregation scheme that (1) assumes that community members are selfish and do not trust each other and uses a secure incentive technique to encourage their contribution; (2) protects the real-world identities of community providers and clients by relying only on disposable opaque identifiers (public/private key pairs); (3) is fully distributed, open to all, and does not rely on any authority to resolve disputes or to control membership; (4) is automated, using standard hardware and software we developed for some of the main available platforms (Linux-based WLAN access points and Windows Mobile-based cell phones). Thus, it can easily complement 2G/3G cellular networks in metropolitan areas where some WCNs provide wide coverage.

ii For the first time in the history of telecommunications, private individuals can provide telecommunication services to their peers. This change was brought on by the emergence of low-cost Wireless Local Area Network (WLAN) technology. WLANs based on the IEEE 802.11 family of specifications are everywhere, from businesses and universities, to hotels and airports. Households with broadband connections also use WLANs for tetherless access to the Internet. WLANs usually cover greater areas than intended with their installation. However, a client that attempts to access a foreign WLAN is likely to fail: most WLANs are secured against outsiders. These WLANs, along with their backhaul connections, represent an underutilized resource. In metropolitan areas, the density of WLANs is high. The Internet access bandwidth they can offer is greater than what 2G cellular offers—even if the backhaul is a simple DSL connection. Newer cell phones are equipped with WLAN adapters. Thus, the stage is set for an alternative public cellular network, one that relies on

Abstract—With the low installation and maintenance cost of IEEE 802.11-based equipment, dense Wi-Fi deployments are a reality, especially in today’s urban areas. This vast number of WLANs can be exploited to achieve low-cost ubiquitous wireless Internet access, which is also demostrated by the emergence of community-based wireless access schemes. In our prior work we have developed a reciprocity-based peer-to-peer architecture for Wi-Fi sharing, where peers provide free Wi-Fi access to others in order to enjoy the same benefit when they are away from their own Wi-Fi network. Our system tries to match peer consumption with contribution and we have shown it to work well for city-scale Wi-Fi sharing communities. However, when attempting to roam outside the city boundaries, the statistics are such that there is typically a lack of consumption-contribution information between consuming and providing members, which hinders the system’s scalability. In this work, we extend our architecture with global-scale roaming capabilities by relaxing the requirement for full decentralization. In particular, we exploit special trusted super-peers which act as representatives of different Wi-Fi sharing communities (e.g., communities of different geographical regions) and which mediate transactions when there is insufficient information about peer contribution history. Extensive simulations show that this super-peer-assisted approach can significantly enhance the system’s performance in terms of roaming coverage. I.