Code Placement and Replacement Strategies for Wideband CDMA OVSF Code Tree Management
IEEE Transactions on Mobile Computing
Design and Analysis of Time-Based Code Allocation Schemes in W-CDMA Systems
IEEE Transactions on Mobile Computing
OVSF code assignment strategies with minimal fragmentations for WCDMA systems
Computer Networks: The International Journal of Computer and Telecommunications Networking
Efficient integration OVSF code management strategies in UMTS
Computer 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
Reducing internal and external fragmentations of OVSF codes in WCDMA systems with multiple codes
IEEE Transactions on Wireless Communications
Dynamic assignment of orthogonal variable-spreading-factor codes in W-CDMA
IEEE Journal on Selected Areas in Communications
Call admission and code allocation strategies for WCDMA systems with multirate traffic
IEEE Journal on Selected Areas in Communications
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Orthogonal variable spreading factor (OVSF) codes in CDMA networks are designed to handle quantized data rates. Handling non-quantized data rates in such networks leads to code capacity wastage if traditional single code assignment is used. Although, the use of multiple codes reduce this wastage capacity but the use of large number of fixed rake combiners per call increase cost and complexity of the system. I propose zero wastage designs in which the rake combiner's usage is made dynamic and the amount of rake combiners used depend upon the rate type, with more combiners given to the rate which deviates significantly from the quantized one. The average number of rakes per call is arbitrarily assumed, and if the rakes used for a particular call are less than the average (which happens for quantized or near quantized calls), the unused rakes can be used by future calls. The performance is significantly improved compared to the fixed rate systems. The amount of codes used on average is less than the codes required for existing multi code designs. In the reduced wastage capacity design, which is a special case of zero wastage designs, some wastage can be tolerated for simplicity and less equipment cost.