Vacant Code Precedence and Call Blocking Reduction in WCDMA Systems based on OVSF Codes

In this paper a code assignment scheme called Next Code Precedence High (NCPH) is proposedfor UTRA-FDD (Universal Terrestrial Radio Access Frequency Division Duplex) systems based on OVSF (Orthogonal Variable Spreading Factor) channelization codes. Using the proposed scheme, the number of codes searched before finding suitable vacant code is least. Also the external code fragmentation which can lead to code blocking is less because of the compact nature of code assignment scheme. Simulation results are presented to compare the reduction in call blocking probability of the proposed scheme with the existing novel assignment schemes.

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