1. A system for estimating motion parameters corresponding to a user, the system comprising: a receiver operable to receive a signal from an external source; an inertial sensor operable to be coupled with the user and arbitrarily oriented relative to the direction of user motion for generation of a signal corresponding to user motion; and a processing system in communication with the receiver and inertial sensor, the processing system operable to at least once, utilize the receiver signal to estimate a first parameter corresponding to a first motion parameter type, utilize the inertial sensor signal to estimate a second parameter corresponding to a second motion parameter type, at least once, generate a user-specific motion model to correlate the first parameter type and second parameter type using at least the first and second estimated parameters, utilize the inertial sensor signal to estimate a third parameter corresponding to the second parameter type, and at least once, utilize the motion model and the third parameter to estimate a fourth parameter corresponding to the first parameter type independent of the receiver signal.