Downlink Capacity Analysis of Collaborative Crossed Timeslots in CDMA TDD Systems

Traffic asymmetry between uplink and downlink is expected to be a remarkable 3G characteristic in cellular mobile multimedia communications. CDMA system with TDD is a good solution to this traffic asymmetry. However, the level of traffic asymmetry may be significantly different from a cell to another cell. To tackle this problem and to support the traffic hot spot, crossed slots are examined. The use of crossed slots is restricted within a certain range of a cell by investigating the inter-cell interference and the maximum planned load factor. We examine the radius of inner zone and discuss the capacity of downlink crossed slots for various neighbor cell environments. Computational results show that the capacity increase in the target cell is outstanding by reducing the service range of neighbor cells. When all six neighbors reduce their service range by 20%, the capacity at target cell crossed slot is increased by 35%. Monte Carlo simulation is performed with large scale fading to verify the numerical analysis.

[1]  Martin Haardt,et al.  The TD-CDMA based UTRA TDD mode , 2000, IEEE Journal on Selected Areas in Communications.

[2]  R. F. Ormondroyd,et al.  An effective dynamic slot allocation strategy based on zone division in WCDMA/TDD systems , 2002, Proceedings IEEE 56th Vehicular Technology Conference.

[3]  Lajos Hanzo.  Intelligent Wireless Networking, Smart Antennas and Adaptive Modulation , 2002 .

[4]  L. Godara.  Application of antenna arrays to mobile communications. II. Beam-forming and direction-of-arrival considerations , 1997, Proc. IEEE.

[5]  Yu-Chee Tseng,et al.  Interference analysis of TDD-CDMA systems with directional antennas , 2003, 2003 IEEE 58th Vehicular Technology Conference. VTC 2003-Fall (IEEE Cat. No.03CH37484).

[6]  Wha Sook Jeon,et al.  Comparison of time slot allocation strategies for CDMA/TDD systems , 2000, IEEE Journal on Selected Areas in Communications.

[7]  Lajos Hanzo,et al.  On the network performance of UTRA-like TDD and FDD CDMA systems using adaptive modulation and adaptive beamforming , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[8]  L. Hanzo,et al.  Genetically enhanced performance of a UTRA-like time-division duplex CDMA network , 2005, 2005 IEEE 61st Vehicular Technology Conference.

[9]  Antti Toskala,et al.  Wcdma for Umts , 2002 .

[10]  Doru Calin,et al.  Impact of radio resource allocation policies on the TD-CDMA system performance: evaluation of major critical parameters , 2001, IEEE J. Sel. Areas Commun..

[11]  Youngnam Han,et al.  An adaptive time slot allocation strategy for W-CDMA/TDD system , 2001, IEEE VTS 53rd Vehicular Technology Conference, Spring 2001. Proceedings (Cat. No.01CH37202).

[12]  J. Limb,et al.  Editorial on the IEEE/OSA Journal of Lightwave Technology and the IEEE Journal on Selected Areas in Communications , 1986 .

[13]  Jad Nasreddine,et al.  Time slot allocation based on a path gain division scheme for TD-CDMA TDD systems , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[14]  J. Laiho-Steffens,et al.  Estimation of capacity and required transmission power of WCDMA downlink based on a downlink pole equation , 2000, VTC2000-Spring. 2000 IEEE 51st Vehicular Technology Conference Proceedings (Cat. No.00CH37026).

[15]  Jang Gyu Lee,et al.  Mobile station location using hybrid GPS and a wireless network , 2003, The 57th IEEE Semiannual Vehicular Technology Conference, 2003. VTC 2003-Spring..

[16]  Lajos Hanzo,et al.  Third-generation systems and intelligent wireless networking , 2002 .

[17]  Lie-Liang Yang,et al.  Uplink capacity investigations of TDD/CDMA , 2002, Vehicular Technology Conference. IEEE 55th Vehicular Technology Conference. VTC Spring 2002 (Cat. No.02CH37367).