Orthogonal Coding for Code Division Multiple Access (CDMA)

Period of Performance: 12/17/2003 - 06/17/2004


Phase 1 SBIR

Recipient Firm

Freedom Vertical Technologies
30 Memorial Parkway
Long Branch, NJ 07740
Principal Investigator


We propose to develop and assess an Orthogonal CDMA cellular communications system that capitalizes on the advantages associated with a unique pseudonoise (PN) code class identified as "Multiplexed Noise" (MN) codes. Employing MN codes for CDMA eliminates all of the major disadvantages of present CDMA systems that employ Maximal Length Sequence (MLS) codes. Those systems are forced to be non-orthogonal and process only a short segment of the MLS code. Obtaining orthogonal operation eliminates the near-far ratio problem and need for power control. This provides the maximum attainable capacity of n (n = the code length) users per cell or sector with no interference between any of the users. Optimum AJ and LPI/LPD is provided with a guaranteed processing gain performance improvement of n for every processed code. We will identify and develop proprietary concepts that can accommodate multiple data rates for spread spectrum systems such as used in LANs and in Future Combat Systems. This provides significant processing gain even for the high data rates associated with video. Using MN codes is still optimum here and several proprietary concepts we have enable combining inputs at different rates and maximizing the code lengths to obtain optimum AJ and LPI/LPD performance.