1. Holma, H., Toksala, A.: WCDMA for UMTS. Wiley, Nokia, Finland (2000)
2. Adachi, F., Sawahashi, M., Okawa, K.: Tree structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile. IEE Electronics Letters 33, 27–28 (1997)
3. Okawa, K., Adachi, F.: Orthogonal Forward Link Using Orthogonal Multi Spreading Factor Codes for Coherent DS-CDMA Mobile Radio. IEICE Transactions on Communication, E81-B (4), 778–779 (1998)
4. Minn, T., Siu, K.: Dynamic Assignment of Orthogonal Variable- Spreading-Factor Codes in W-CDMA. IEEE Journal on Selected Areas in Communications 18(8), 1429–1440 (2000)
5. Chao, C.M., Tseng, Y.C., Wang, L.C.: Reducing Internal and External Fragmentations of OVSF Codes in WCDMA Systems with Multiple Codes. In: Proc. IEEE Wireless Communications and Networking Conf., vol. 1, pp. 693–698 (2003)