Abstract-In universal terrestrial radio access (UTRA) systems, orthogonal variable spreading factor (OVSF) codes are used to support different transmission rates for different users. In this paper, we first define the flexibility index to measure the capability of an assignable code set in supporting multirate traffic classes. Based on this index, two single-code assignment schemes, nonrearrangeable and rearrangeable compact assignments, are proposed. Both schemes can offer maximal flexibility for the resulting code tree after each code assignment. We then present an analytical model and derive the call blocking probability, system throughput and fairness index. Analytical and simulation results show that the proposed schemes are efficient, stable and fair. Index Terms-Code assignment, orthogonal variable spreading factor (OVSF) code, universal terrestrial radio access (UTRA).
In REF , the concept of flexibility index defined, and based on this index two single code assignment designs namely non rearrangeable and rearrangeable compact assignments are given.
Maximally flexible assignment of orthogonal variable spreading factor codes for multirate traffic
IEEE Transactions on Wireless Communications
IEEE Transactions on Wireless Communications
Computer Science