A method to collect media exposure data, the method comprising: collecting a cookie at a processing device based on media exposure data obtained by the processing device; registering a portable device closest to the processing device; and in response to instructions embedded in the media exposure data, sending a message to a collection server, the message including information about the processing device, the information including the cookie, wherein the registered portable device is one of a plurality of portable devices (102, 103, 104), and the method further including identifying a closest one of the plurality of portable devices (102, 103, 104) by: collecting signal characteristics corresponding to the wireless communication between respective ones of the plurality of portable devices (102, 103, 104) and the processing device; and selecting the closest one of the plurality of portable devices (102, 103, 104) based on one of the signal characteristics being comparatively best relative to others of the signal characteristic, wherein the cookie causes the collection server to credit a user of the portable device closest to the processing device with being exposed to the media, and wherein the one of the signal characteristics is one of a link quality, a signal strength, or a transmit power level. collecting a cookie at a processing device based on media exposure data obtained by the processing device; registering a portable device closest to the processing device; and in response to instructions embedded in the media exposure data, sending a message to a collection server, the message including information about the processing device, the information including the cookie, wherein the registered portable device is one of a plurality of portable devices (102, 103, 104), and the method further including identifying a closest one of the plurality of portable devices (102, 103, 104) by: collecting signal characteristics corresponding to the wireless communication between respective ones of the plurality of portable devices (102, 103, 104) and the processing device; and selecting the closest one of the plurality of portable devices (102, 103, 104) based on one of the signal characteristics being comparatively best relative to others of the signal characteristic, wherein the cookie causes the collection server to credit a user of the portable device closest to the processing device with being exposed to the media, and wherein the one of the signal characteristics is one of a link quality, a signal strength, or a transmit power level. collecting signal characteristics corresponding to the wireless communication between respective ones of the plurality of portable devices (102, 103, 104) and the processing device; and selecting the closest one of the plurality of portable devices (102, 103, 104) based on one of the signal characteristics being comparatively best relative to others of the signal characteristic, wherein the cookie causes the collection server to credit a user of the portable device closest to the processing device with being exposed to the media, and wherein the one of the signal characteristics is one of a link quality, a signal strength, or a transmit power level.