CDMA: principles of spread spectrum communication
CDMA: principles of spread spectrum communication
Code Placement and Replacement Strategies for Wideband CDMA OVSF Code Tree Management
IEEE Transactions on Mobile Computing
IEEE Transactions on Mobile Computing
Reducing internal and external fragmentations of OVSF codes in WCDMA systems with multiple codes
IEEE Transactions on Wireless Communications
Wideband DS-CDMA for next-generation mobile communications systems
IEEE Communications Magazine
UMTS/IMT-2000 based on wideband CDMA
IEEE Communications Magazine
Dynamic assignment of orthogonal variable-spreading-factor codes in W-CDMA
IEEE Journal on Selected Areas in Communications
Call elapsed time and reduction in code blocking for WCDMA networks
SoftCOM'09 Proceedings of the 17th international conference on Software, Telecommunications and Computer Networks
A fair multi code OVSF design for 3G and beyond wireless networks
SoftCOM'09 Proceedings of the 17th international conference on Software, Telecommunications and Computer Networks
An efficient multi code design for code blocking reduction in 3G wireless networks
Sarnoff'10 Proceedings of the 33rd IEEE conference on Sarnoff
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OVSF codes are used as channelization codes in WCDMA. In this paper a number of OVSF code assignment and reassignment strategies are proposed. We can use these schemes in accordance to the benefit required. Leftmost code assignment (LCA) of OVSF scheme is first proposed which provides benefit of less code searches and no reassignments, saving extra overhead in transmission. Limitation of LCA scheme is code blocking which increases the blocking probability of calls. Code blocking can be avoided by using code reassignments. Ancestor cost assignment scheme is used to make assignment compact so that vacant codes are available for higher rate calls. This reduces the blocking compared to DCA scheme. Class partition assignment divides all OVSF codes into different sets. The users with different rates(classes) are assigned different sets. The class partition assignment scheme reduces number of code searches compared to DCA assignment and reassignment schemes. Blocking in class partition assignment scheme can be reduced by reserving some OVSF codes for reassignments. Matlab is as simulation tool used to demonstrate the results.