PHONE LINGan, Chai-HienChai-HienGanHsu, Ching-ChiChing-ChiHsu2009-05-062018-07-052009-05-062018-07-05200500189545http://ntur.lib.ntu.edu.tw//handle/246246/155230https://www.scopus.com/inward/record.uri?eid=2-s2.0-17644396659&doi=10.1109%2fTVT.2004.842449&partnerID=40&md5=3e842dc56b8ca8f97feb3cb793093460The Universal Mobile Telecommunications System (UMTS) provides users variable data rate services, which adopts wide-band code-division multiple-access (WCDMA) as the radio access technology. In WCDMA, orthogonal variable spreading factor (OVSF) codes are assigned to different users to preserve the orthogonality between users' physical channels. The data rate supported by an OVSF code depends on its spreading factor (SF). An OVSF code with smaller SF can support higher data rate services than that with larger SFs. Randomly assigning the OVSF code with a large SF to a user may preclude a larger number of OVSF codes with small SFs, which may cause lots of high data rate call requests to be blocked. Therefore the OVSF code assignment affects the performance of the UMTS network significantly. In this paper, we propose two OVSF code assigmnent schemes CADPB1 and CADPB2 for UMTS. Both schemes are simple and with low system overhead. The simulation experiments are conducted to evaluate the performances for our schemes. Our study indicates that our proposed schemes outperform previously proposed schemes in terms of the weighted blocking probability and fairness index. Our schemes improve the call acceptance rate by slightly introducing call waiting time. © 2005 IEEE.application/pdf566018 bytesapplication/pdfen-USCode channel assigmnent; Dynamic adjustment; Orthogonal variable spreading factor (OVSF); Universal Mobile Telecommunications System (UMTS); Wide-band code-division multiple-access (WCDMA)Code division multiple access; Codes (symbols); Communication channels (information theory); Computer simulation; Radio communication; Code channel assignment; Orthogonal variable spreading factor; Universal mobile telecommunication systems; Wideband code division multiple access; Mobile telecommunication systemsjournal article10.1109/TVT.2004.8424492-s2.0-17644396659http://ntur.lib.ntu.edu.tw/bitstream/246246/155230/1/08.pdf