LDS-OFDM an Efficient Multiple Access Technique

In this paper LDS-OFDM is introduced as an uplink multicarrier multiple access scheme. LDS-OFDM uses Low Density Signature (LDS) structure for spreading the symbols in frequency domain. This technique benefits from frequency diversity besides its ability of supporting parallel data streams up to 400% more than the number of subcarriers (overloaded condition). The performance of LDS-OFDM is evaluated and compared with conventional OFDMA systems over multipath fading channel. Monte Carlo based simulations for various loading conditions indicate significant performance improvement over OFDMA system.

[1]  Ferry Preska. Wathan.  Low-density signature communications in overloaded synchronous CDMA systems , 2007 .

[2]  Hui Liu,et al.  An Analysis on Uplink OFDMA Optimality , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[3]  Lajos Hanzo,et al.  OFDM and MC-CDMA for Broadband Multi-User Communications, WLANs and Broadcasting , 2003 .

[4]  Reza Hoshyar,et al.  Dynamic Grouped Chip-Level Iterated Multiuser Detection Based on Gaussian Forcing Technique , 2008, IEEE Communications Letters.

[5]  Reza Hoshyar,et al.  Novel Low-Density Signature for Synchronous CDMA Systems Over AWGN Channel , 2008, IEEE Transactions on Signal Processing.

[6]  David Tse,et al.  Fundamentals of Wireless Communication , 2005 .

[7]  Alister G. Burr,et al.  Frequency Diversity Comparison of Coded SC-FDE & OFDM on Different Channels , 2007, 2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications.

[8]  Ramjee Prasad,et al.  OFDM for Wireless Multimedia Communications , 1999 .

[9]  Soura Dasgupta,et al.  Optimum multiuser OFDM systems with unequal subchannel assignment , 2003, IEEE International Conference on Communications, 2003. ICC '03..