UCLA/Cisco Metropolitan Wi-Fi Research Network Vidyut Samanta * , Jason Ryder * , Sona Chaudhuri * , Jeff Burke † , Deborah Estrin * , and Fabian Wagmister † * Computer Science Department, UCLA Email: vids@ucla.edu, jryder@cs.ucla.edu, sona310@ucla.edu, destrin@cs.ucla.edu, † Department of Film, Television & Digital Media, UCLA Email: jburke@ucla.edu, fabian@ucla.edu Abstract—We are deploying a metropolitan scale Wi-Fi mesh network near downtown Los Angeles to support the design and development of a data-centric network-fabric for urban participatory sensing. Participatory sensing employs software and network technol- ogy to enable people’s everyday mobile devices to act as credible sensors of the natural, built, and cultural environments. Current research focuses on how to make it easy and secure for both the public and professional users to define sensing ‘campaigns,’ recruit participants to collect data, to help ‘make a case’ with data they collect, and digitally publish the results. To further research in this area, our architecture will enable embedding network–attested location and time context in sensor readings. The network will also provide a research framework for developing policy-based privacy, and related security mechanisms for participatory sensing. I. I NTRODUCTION The mayor of Los Angeles wants citywide wireless access. He proposes a Wi-Fi plan that would provide free or low- cost Internet services over 498 square miles in 2009[1]. Our project explores the potential that a large scale Wi-Fi deployment offers to communities in documenting their own environments, and contributing to healthy and livable cities through participatory sensing. We are expanding UCLA’s urban-sensing network into the community by deploying a metropolitan scale Wi-Fi mesh network in collaboration with California State Parks around the new Los Angeles State Historic Park (LA SHP), a 32- acre site directly adjacent to LA downtown. The network will connect two campus centers and the LA State Historic Park. Figure 1 shows the locations. Fig. 1. Met-Wi Locations The network will also provide a research framework for developing policy-based privacy, and related security mechanisms for participatory sensing, including embedding network–attested location and time in sensor readings. We will perform long–term technology research on how networks can support communities in documenting their own environments as part of creating healthy and livable cities; and collaborative work with local communities that investigates how emerging technologies can be employed to express their identities and histories in today’s mediatized society. II. NETWORK ARCHITECTURE Fig. 2. Architecture Equipment Purpose Cisco Location Appliance 2710 Processes Wi-Fi location data Cisco Aironet 1510 Mesh AP Access Points WLAN Controller 2000 Series Supports the mesh network Cisco 3845 Integrated Router Connect sites & provide VPN & DHCP TABLE I EQUIPMENT USED IN WI -FI MESH NETWORK Figure 2 presents the architectural layout of the network. We will use five access points to cover each of the UCLA campus sites, six access points to cover the LA SHP and four will be used for a portable system. This is more access points than necessary to cover each of these locations, but we have chosen to do this in order to get better localization information from the system, which is performed using RF Fingerprinting[2]. RF Fingerprinting uses a database of fingerprints of each co-ordinate on the floor-plan of the area being covered. A fingerprint is calculated using signal strength and taking into consideration factors including reflection, attenuation, and multi-path. A clients location is found by querying the fingerprint database with the signal strength reported by all the access-points that can see the client. At each of our locations only one access point will be connected to the router, this will be the root access point the others will be connected to the root access point in an ad-hoc