Wideband DS-CDMA for next-generation mobile communications systems
IEEE Communications Magazine
Quality of service for multimedia CDMA
IEEE Communications Magazine
Spread spectrum access methods for wireless communications
IEEE Communications Magazine
Dynamic assignment of orthogonal variable-spreading-factor codes in W-CDMA
IEEE Journal on Selected Areas in Communications
Fair Single Code and Multi Code Designs for 3G and Beyond CDMA Systems
Wireless Personal Communications: An International Journal
Top Down Code Search to Locate An Optimum Code and Reduction in Code Blocking for CDMA Networks
Wireless Personal Communications: An International Journal
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In this paper, a fast dynamic code assignment (FDCA) algorithm is proposed to assign a single Orthogonal Variable Spreading Factor (OVSF)-code for a data rate requirement in next generation wireless access networks. Our algorithm uses the code assignment operation to evaluate the cost for an OVSF-code allocation. The cost is determined by maintaining the data structure that keeps track the number of available and occupied descendant codes of the code. Based on the cost assignment operation, FDCA algorithm can assign an OVSF-code by reassigning occupied descendant codes for a requested data rate. The OVSF-codes assigned by our algorithm is unrestricted with decreasing spreading factor. Moreover, two types of simulations and experimental measurements are presented. First, the proposed algorithm is applied on the OVSF-code assignment of restricted spreading vector. Our experimental results show that the number of reassigned OVSF-codes within FDCA algorithm is reduced comparing to other scheme proposed in the literature. Then, for serving higher data rate requirements, our scheme also shows significant improvement on the spectral efficiency over fixed code assignment scheme.