Patent ID: 7039321

Claim:
A method of signal acquisition over an optical wireless communication link comprising randomly adjusting an acquisition scan pattern, such that final alignment is achieved in a shorter period of time than that achievable without application of the random scan pattern adjustment, and further such that the final alignment is improved beyond that achievable without application of the random scan pattern adjustment, wherein the step of randomly adjusting a scan comprises the steps of: (a) periodic sampling of the optical wireless communication link during a final signal acquisition cycle to detect the absence of new feedback information; (b) determining whether a first predetermined number of samples has been received without new feedback information to define a first signal acquisition condition; (c) determining a location associated with an acquisition spiral at which the most recent acquisition transpired prior to any occurrence of the first signal acquisition condition; (d) modifying the location with a nudge in a random direction to define a new center associated with the acquisition spiral subsequent to any occurrence of the first signal acquisition condition; (e) acquiring data signals using an acquisition spiral having the new center to determine whether a second predetermined number of samples have been received without new feedback information to define a second signal acquisition condition subsequent to any occurrence of the first signal acquisition condition; otherwise (f) acquiring data signals using the acquisition spiral having a desired scan pattern without a newly defined center in the absence of the first signal acquisition condition to determine whether a second predetermined number of samples have been received without new feedback information to define a second signal acquisition condition; (g) increasing the maximum radius associated with the acquisition spiral having the new center by a predetermined amount upon the occurrence of the second signal acquisition condition; (h) acquiring data signals with the acquisition spiral having the new center and the increased maximum radius to determine if a predetermined acquisition criteria has been met upon the occurrence of the second signal acquisition condition; otherwise (i) acquiring data signals with the acquisition spiral determined in step (f) to determine if a predetermined acquisition criterion has been met upon the absence of the second signal acquisition condition; (j) repeating steps (a)–(i) when the acquisition criteria has not been met; and (k) halting the random adjustment of the scan pattern and continuously acquiring data signals using the most recent acquisition spiral determined in steps (g) and (h) when the acquisition criteria has been met.