New code match strategy for wideband code division multiple access code tree management

Abstract

Orthogonal variable spreading factor channelization codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. A new code match scheme for WCDMA code tree management was proposed. The code match scheme is similar to the existing crowed-first scheme. When choosing a code for a user, the code match scheme only compares the one up layer of the allocated codes, unlike the crowed-first scheme which perhaps compares all up layers. So the operation of code match scheme is simple, and the average time delay is decreased by 5.1%. The simulation results also show that the code match strategy can decrease the average code blocking probability by 8.4%.

Keywords

orthogonal variable spreading factor / code placement strategy / code match strategy / code blocking probability

References

[1] AdachiF, SawahashiM, SudaH. Wideband CDMA for next: generation mobile communications systems[J]. IEEE Communication Magazine, 1998, 36(9): 56-69

[2] DahlmanE, GudmundsonB, NilssonM, et al. . UMTS/IMT—2000 based on wideband CDMA[J]. IEEE Communication Magazine, 1998, 36(9): 70-80

[3] HolmaH, ToskalaAWCDMA for UMTS[M], 2000, New York, John Wiley and Sons

[4] BaierA. Design study for a CDMA-based third-generation mobile radio system[J]. IEEE J on Selected Areas in Communications, 1994, 12(4): 733-743

[5] ViterbiA JCDMA: principles of spread spectrum communication[M], 1995, New York, Addison Wesley

[6] RappaportT SWireless communications: Principles and practice[M], 1996, NJ, Prentice-Hall

[7] GargV KIS-95 CDMA and Cdma2000[M], 2000, New Jersey, Prentice Hall

[8] SklarBDigital communications: fundamentals and applications[M], 2001, New Jersey, Prentice Hall

[9] MinnT, SiuK Y. Dynamic assignment of orthogonal variable-spreading-factor codes in W-CDMA[J]. IEEE J on Selected Areas in Communications, 2000, 18(8): 1429-1440

[10] TsengY C, ChaoC M. Code placement and replacement strategies for wideband CDMA OVSF code tree management[J]. IEEE Transaction on Mobile Computing, 2002, 1(4): 293-302

[11] AdachiF, SawahashiM, OkawaK. Tree-structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile radio[J]. Electronic Letters, 1997, 33: 27-28

[12] Yang Y, Yum T S P. Nonrearrangeable compact assignment of orthogonal variable-spreading-factor codes for multirate traffic[C]// Proceeding of IEEE Vehicular Technology Conference. New Jersey, 2001: 938–942.

[13] YangY, YumT S P. Maximally flexible assignment of orthogonal variable spreading factor codes for multirate traffic[J]. IEEE Transaction on Wireless Communications, 2004, 3(3): 781-792

[14] AmicoM D, MaffioliF, MeraniM L. A tree partitioning dynamic policy for OVSF codes assignment in wideband CDMA[J]. IEEE Transactions on Wireless Communications, 2004, 3(4): 1013-1017

[15] LinP, GanC H, HsuC C. OVSF code channel assignment with dynamic code set and buffering adjustment for UMTS[J]. IEEE Transaction Vehicular Technology, 2005, 54(2): 591-602