Margin adaptive optimization in multi-user MISO-OFDM systems under rate constraint

In this paper, we focus on the total transmission power minimization problem for downlink beamforming multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems while ensuring each user's QoS requirement. Although the linear integer programming (LIP) solution we formulate provides the performance upper bound of the margin adaptive (MA) optimization problem, it is hard to be implemented in practice due to its high computational complexity. By regarding each user's equivalent channel gain as approximate independent values and using iterative descent method, we present a heuristic MA resource allocation algorithm. Simulation results show that the proposed algorithm efficiently converges to the local optimum, which is very close to the performance of the optimal LIP solution. Compared with existing space division multiple access (SDMA) OFDM systems with or without adaptive resource allocation, the proposed algorithm achieves significant performance improvement by exploiting the frequency diversity and multi-user diversity in down-link multiple-input single-output (MISO) OFDM systems.

[1]  Jae Hong Lee,et al.  Efficient subcarrier and bit allocation algorithm for OFDMA system with adaptive modulation , 2004, 2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring (IEEE Cat. No.04CH37514).

[2]  Ross D. Murch,et al.  A transmit preprocessing technique for multiuser MIMO systems using a decomposition approach , 2004, IEEE Transactions on Wireless Communications.

[3]  Roger S. Cheng,et al.  Optimal resource allocation in SDMA/multiinput-single-output/OFDM systems under QoS and power constraints , 2004, 2004 IEEE Wireless Communications and Networking Conference (IEEE Cat. No.04TH8733).

[4]  Beomsup Kim,et al.  On the use of linear programming for dynamic subchannel and bit allocation in multiuser OFDM , 2001, GLOBECOM'01. IEEE Global Telecommunications Conference (Cat. No.01CH37270).

[5]  Tricia J. Willink,et al.  Optimization and performance evaluation of multicarrier transmission , 1997, IEEE Trans. Inf. Theory.

[6]  Hugo De Man,et al.  Adaptive loading for OFDM/SDMA-based wireless networks , 2002, IEEE Trans. Commun..

[7]  Khaled Ben Letaief,et al.  Adaptive resource allocation for multiaccess MIMO/OFDM systems with matched filtering , 2005, IEEE Transactions on Communications.

[8]  Leandros Tassiulas,et al.  Adaptive resource allocation in SDMA-based wireless broadband networks with OFDM signaling , 2002, Proceedings.Twenty-First Annual Joint Conference of the IEEE Computer and Communications Societies.

[9]  Khaled Ben Letaief,et al.  Multiuser OFDM with adaptive subcarrier, bit, and power allocation , 1999, IEEE J. Sel. Areas Commun..

[10]  Andrea J. Goldsmith,et al.  Degrees of freedom in adaptive modulation: a unified view , 2001, IEEE Trans. Commun..

[11]  Yih-Fang Huang,et al.  An Opportunistic Downlink Mimo-Ofdm Scheme , 2006, 2006 IEEE International Conference on Acoustics Speech and Signal Processing Proceedings.