Fixed wireless loop system that ranks non-assigned PN codes to reduce interference

DETAILED DESCRIPTION The foregoing and other problems are overcome and the objects and advantages are realized by methods and apparatus in accordance with embodiments of this invention.
Disclosed is a method for operating a fixed wireless system having a radio base unit (RBU) that uses a code division multiple access (CDMA) airlink for communicating with a plurality of subscriber units (SUs) within a coverage area of the RBU.
The method includes establishing, from a set of pseudonoise (PN) spreading codes, a subset of PN spreading codes that are currently assigned to SUs and a subset of PN spreading codes that are currently not assigned to SUs.
The method further ranks the PN spreading codes from the subset of non-assigned PN spreading codes by an amount of interference experienced by the use of eaci non-assigned PN spreading code, and assigns to an SU requiring a PN spreading code a PN spreading code front the set of non-assigned PN spreading codes that is ranked as having a least amount of interference.
The step of ranking the non-assigned PB spreading codes is preferably performed periodically, and includes the steps of assigning, in turn, individual ones of the PN spreading codes from the set of non-assigned PN spreading codes to a correlator of the RBU, and determining an amount of noise output from the correlator resulting from the use of the PN spreading code.