1. A method of uplink carrier handoff in a multiple carrier communication system, the multiple carriers include a higher frequency carrier and a lower frequency carrier, the higher frequency carrier being at a higher frequency than the lower frequency carrier, the method comprising: receiving, by a network element, a measurement report from a mobile providing information regarding path loss as measured at the mobile for a serving one of the multiple carriers on the downlink, the serving carrier being the carrier over which the mobile communicates on the uplink; and selectively sending, by the network element, an instruction to the mobile to handoff to a non-serving one of the multiple carriers depending on whether a threshold requirement associated with the serving carrier has been met, the meeting of the threshold requirement being based on the received path loss, and each of the multiple carriers having an associated threshold requirement, wherein the associated threshold requirements for the higher frequency carrier and the lower frequency carrier are established based on differences in propagation characteristics of the higher frequency carrier and the lower frequency carrier, wherein each of the multiple carriers is associated with a different threshold requirement.