Code placement and replacement strategies for wideband CDMA OVSF code tree management
學年 90
學期 1
發表日期 2001-11-01
作品名稱 Code placement and replacement strategies for wideband CDMA OVSF code tree management
著者 Tseng, Y. C.; Chao, C. M.; Wu, S. L.
作品所屬單位 淡江大學電機工程學系 San Antonio, MEXICO
出版者 IEEE
會議名稱 IEEE Global Telecommunications Conference
摘要 The use of OVSF codes in WCDMA systems has offered opportunities to provide variable data rates to flexibly support applications with different bandwidth requirements. Two important issues in such an environment are the code placement problem and code replacement problem. The former may have significant impact on code utilization and, thus, code blocking probability, while the latter may affect the code reassignment cost if dynamic code assignment is to be conducted. The general objective is to make the OVSF code tree as compact as possible so as to support more new calls by incurring less blocking probability and less reassignment costs. Earlier studies about these two problems either do not consider the structure of the OVSF code tree or cannot utilize the OVSF codes efficiently. To reduce the call blocking probability and the code reassignment cost, we propose two simple yet efficient strategies that can be adopted by both code placement and code replacement: leftmost and crowded-first. Numerical analyses on call blocking probability and bandwidth utilization of OVSF code trees when code reassignment is supported are provided. Our simulation results show that the crowded-first strategy can significantly reduce, for example, the code blocking probability by 77 percent and the number of reassignments by 81 percent, as opposed to the random strategy when the system is 80 percent fully loaded and the max SF = 256.
語言 en
會議性質 國內
國別 MEX
公開徵稿 Y
出版型式 紙本
出處 IEEE Global Telecommunications Conference, v.1,pp.293 - 302

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