Google Wi Fi

Description

The GoogleWiFi network is an operational, large-scale, wireless multi-hop network of multi-tier architecture. It is deployed in Mountain View, CA by Google. The following page presents data that was obtained and used for a paper in MobiCom 2008. The measurements were completed October 3-10, 2007 by Joshua Robinson.

GoogleWiFi Gateway Node

As of October 2007, when the measurements were taken, the network consists of 447 wireless nodes that provide coverage to an area of 31 km². Our measurements are contained to a 12 km² area in the northwest quadrant of the network, encompassing 168 of the mesh nodes. The mesh nodes are based on Tropos hardware, mounted mostly on city light poles (as shown in the image above). The Tropos nodes consist of a 7.4 dBi antenna and a single 802.11g wireless interface. The client measurement platform for the GoogleWiFi study was an IBM T42 laptop with an external 802.11g wireless adapter, 3 dBi antenna, and GPS receiver.

Mesh Node Locations

The GPS coordinates of all 168 measured mesh nodes can be found here. The format of each line is [latitude longitude]. Also note that the row numbers in this file correspond to the 'ID' field in the measurement data below.

The full set of 451 node coordinates can be found here. The format of each line is [is_gateway latitude longitude] where the first field is '1' to indicate if the mesh node is a gateway and '0' otherwise. Extra nodes might be included, because certain APs were potentially replaced by Google, however this is not certain. The mesh node locations were obtained from the GoogleWiFi website and coverage map.

Terrain Map for Mountainview

The terrain map used for our study is an economic zoning map of the city of Mountain View, California. The original PDF can be downloaded here, as well as the extracted image (PNG) file that we used to import the terrain info into Matlab. The original source is the city of Mountain View's website and copyright credit for the map goes to the city.

Coverage (SNR) Measurements for GoogleWiFi

The full set of coverage measurements can be found here.

The signal strength measurements were obtained with NetStumbler and a small amount of pre-processing was done to remove all none GoogleWiFi measurements and to associate the observed MAC addresses with node locations. Google asked that the MAC addresses and IP addresses are not given, hence the data provided has been slightly anonymized. An important point to note is that this data only includes the positive measurements, whereas any packets below 14 dB SNR did not appear in the original wardrive data and so one must infer the existence of a coverage hole. Each line represents one reading from an AP beacon. The format of each line is:
[latitude longitude node_id SNR SigStrength noise channel]
where latitude and longitude indicate the position the laptop was in, node_id indicates which mesh node the beacon was received from (indexed to node list, SNR is the received signal strength in dB, SigStrength is the received signal in dBm, noise is the measured noise in dBm, and channel indicates the 802.11g channel used (i.e., 1-11).

The full set of all measurements (coverage, node locations, maps) can be found here.

Researchers that make use of the data for any purpose, are kindly requested to cite the following publication:
J. Robinson, R. Swaminathan, and E. Knightly, "Assessment of Urban-Scale Wireless Networks with a Small Number of Measurements", Proceedings of ACM MobiCom 2008, San Francisco, CA, September 2008. (bibtex: Show).

TFA Measurements

In the MobiCom 2008 paper, GoogleWiFi measurements were evaluated alongside measurements from the TFA network. This set of TFA measurements can be found here.