We study the important problem of resource allocation for the downlink of Multiple-Input Multiple output (MIMO) Multicast Wireless Systems operating over frequency-selective channels and we propose a low-complexity but efficient resource allocation algorithm for MIMO-enabled OFDMA systems. The proposed solution guarantees a minimum spectrum share for each user while also takes advantage of the multicast transmission mode. The presence of multiple antennas in both transmitter and receiver offers spatial diversity to the system along with the frequency diversity added by the OFDMA access scheme. The computational complexity is reduced from exponential to linear and validation of the proposed solution is achieved through various simulation scenarios in comparison with other multicast and unicast reference schemes used in MIMO-OFDMA systems. Numerical results and complexity analysis demonstrate the feasibility of the proposed algorithm. 1. Introduction Future wireless systems along with voice are envisioned to provide plethora of rich multimedia services like mobile TV, video conferencing, and so forth, with various bandwidth requirements [1–5]. The introduction of new applications such as streaming video and up-to-date information distribution services (e.g., news, stock market, weather forecasting, etc.) has brought about the need for communication between one sender and many receivers. Communication between one transmitter and multiple receivers can be achieved by either the unicast or the multicast transmission mode [1–8]. Works [1–4] study Multimedia Broadcast Multimedia Service (MBMS) delivery to large group of users. Particularly, in [1, 2] authors conclude that a hybrid unicast-multicast delivery offers the best system resource utilization, while in [3], the case of reserved resources for multicast services is investigated and in [4] the use of multiple transmit and receive antennas is considered for multicasting, in order to achieve higher data rates. However, the aforementioned studies refer to Wideband Code Division Multiple Access (WCDMA) mobile networks and Orthogonal Frequency Division Multiple Access (OFDMA) scheme is the modulation and multiple access scheme adopted for next-generation wireless systems [5–17]. OFDMA is based on Orthogonal Frequency Modulation (OFDM) scheme and helps exploit multiuser diversity in frequency-selective channels, since it is very likely that some subcarriers that are in deep fade for some users are in good channel state for at least one of the other users [9, 12, 14]. Because of its superior performance over
References
[1]
F. Hartung, U. Horn, J. Huschke, M. Kampmann, T. Lohmar, and M. Lundevall, “Delivery of broadcast services in 3G networks,” IEEE Transactions on Broadcasting, vol. 53, no. 1, pp. 188–198, 2007.
[2]
A. Alexiou, C. Bouras, V. Kokkinos, and E. Rekkas, “An improved mechanism for multiple MBMS sessions assignment in B3G cellular networks,” Wireless Networks, vol. 16, no. 3, pp. 671–686, 2010.
[3]
Y.-C. Lai, P. Lin, Y. Fang, and W.-H. Chen, “Channel allocation for UMTS multimedia broadcasting and multicasting,” IEEE Transactions on Wireless Communications, vol. 7, no. 11, pp. 4375–4383, 2008.
[4]
A. M. C. Correia, J. C. M. Silva, N. M. B. Souto, L. A. C. Silva, A. B. Boal, and A. B. Soares, “Multi-resolution broadcast/multicast systems for MBMS,” IEEE Transactions on Broadcasting, vol. 53, no. 1, pp. 224–233, 2007.
[5]
M. R. Chari, F. Ling, A. Mantravadi et al., “FLO physical layer: an overview,” IEEE Transactions on Broadcasting, vol. 53, no. 1, pp. 145–159, 2007.
[6]
J. Liu, W. Chen, Z. Cao, and K. B. Letaief, “Dynamic power and subcarrier allocation for OFDMA-based wireless multicast systems,” in Proceedings of the IEEE International Conference on Communications (ICC '08), Beijing, China, May 2008.
[7]
J. Y. Kim, T. Kwon, and D. H. Cho, “Resource allocation scheme for minimizing power consumption in OFDM multicast systems,” IEEE Communications Letters, vol. 11, no. 6, pp. 486–488, 2007.
[8]
J. Xu, S. J. Lee, W. S. Kang, and J. S. Seo, “Adaptive resource allocation for mimo-ofdm based wireless multicast systems,” IEEE Transactions on Broadcasting, vol. 56, no. 1, pp. 98–102, 2010.
[9]
I. G. Fraimis, V. D. Papoutsis, and S. A. Kotsopoulos, “A decentralized subchannel allocation scheme with Inter-cell Interference Coordination (ICIC) for multi-cell OFDMA systems,” in Proceedings of the 53rd IEEE Global Communications Conference (GLOBECOM '10), December 2010.
[10]
Y. Ben-Shimol, I. Kitroser, and Y. Dinitz, “Two-dimensional mapping for wireless OFDMA systems,” IEEE Transactions on Broadcasting, vol. 52, no. 3, pp. 388–396, 2006.
[11]
J. Jang and K. B. Lee, “Transmit power adaptation for multiuser OFDM systems,” IEEE Journal on Selected Areas in Communications, vol. 21, no. 2, pp. 171–178, 2003.
[12]
G. Li and H. Liu, “On the optimality of the OFDMA network,” IEEE Communications Letters, vol. 9, no. 5, pp. 438–440, 2005.
[13]
T. C. H. Alen, A. S. Madhukumar, and F. Chin, “Capacity enhancement of a multi-user OFDM system using dynamic frequency allocation,” IEEE Transactions on Broadcasting, vol. 49, no. 4, pp. 344–353, 2003.
[14]
V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, “Fairness-aware resource allocation for the SISO downlink over frequency-selective channels,” in Proceedings of the IEEE Wireless Communications and Networking Conference (WCNC '10), April 2010.
[15]
M. Ergen, S. Coleri, and P. Varaiya, “Qos aware adaptive eesource allocation techniques for fair scheduling in OFDMA based broadband wireless access systems,” IEEE Transactions on Broadcasting, vol. 49, no. 4, pp. 362–370, 2003.
[16]
C. S. Bae and D. H. Cho, “Fairness-aware adaptive resource allocation scheme in multihop OFDMA systems,” IEEE Communications Letters, vol. 11, no. 2, pp. 134–136, 2007.
[17]
V. D. Papoutsis, I. G. Fraimis, and S. A. Kotsopoulos, “Resource allocation algorithm for MIMO-OFDMA systems with minimum resources guarantee,” in Proceedings of the IEEE International Conference on Electronics, Cicuits and Systems (ICECS '10), Athens, Greece, December 2010.
[18]
P. W. C. Chan and R. S. Cheng, “Capacity maximization for zero-forcing MIMO-OFDMA downlink systems with multiuser diversity,” IEEE Transactions on Wireless Communications, vol. 6, no. 5, pp. 1880–1889, 2007.
[19]
G. Li and H. Liu, “On the optimality of downlink OFDMA MIMO systems,” in Proceedings of the 38th IEEE Asilomar Conference on Signals, Systems and Computers, pp. 324–328, California, Calif, USA, November 2004.
[20]
Z. J. Guan, H. Li, C. Q. Xu, X. L. Zhou, and W. J. Zhang, “Adaptive subcarrier allocation for MIMO-OFDMA wireless systems using Hungarian method,” Journal of Shanghai University, vol. 13, no. 2, pp. 146–149, 2009.
[21]
J. Xu, J. Kim, W. Paik, and J. S. Seo, “Adaptive resource allocation algorithm with fairness for MIMO-OFDMA system,” in Proceedings of the IEEE Vehicle Technology Conference (VTC '06), Melbourne, Australia, May 2006.
[22]
A. N. Zaki and A. O. Fapojuwo, “A graph-based resource allocation algorithm for downlink MIMO-OFDMA networks,” in Proceedings of the IEEE Global Telecommunications Conference (GLOBECOM '09), December 2009.
[23]
M. S. Maw and I. Sasase, “Resource allocation scheme in MIMO-OFDMA system for user's different data throughput requirements,” IEICE Transactions on Communications, vol. E91-B, no. 2, pp. 494–504, 2008.
[24]
B. Da and C. C. Ko, “Resource allocation in downlink MIMO-OFDMA with proportional fairness,” Journal of Communications, vol. 4, no. 1, pp. 8–13, 2009.
[25]
S. Xiao, X. Xiao, B. Li, and Z. Hu, “Adaptive subcarrier allocation for multiuser MIMO OFDM systems in frequency selective fading channel,” in Proceedings of the IEEE International Wireless Communications, Networking & Mobile Computing Conference, Wuhan, China, 2005.
[26]
X. Lu and Z. Li, “An adaptive resource allocation algorithm based on spatial subchannel in multiuser MIMO/OFDM systems,” in Proceedings of the IEEE International Conference on Communications (ICC '08), J. Cai and X. Chen, Eds., Beijing, China, May 2008.
[27]
H. Rohling and R. Grunheid, “Performance comparison of different multiple access schemes for the downlink of an OFDM communication system,” in Proceedings of the IEEE Vehicle Technology Conference (VTC '97), May 1997.
[28]
S. T. Chung and A. J. Goldsmith, “Degrees of freedom in adaptive modulation: a unified view,” IEEE Transactions on Communications, vol. 49, no. 9, pp. 1561–1571, 2001.
[29]
G. Li and H. Liu, “Downlink radio resource allocation for multi-cell OFDMA system,” IEEE Transactions on Wireless Communications, vol. 5, no. 12, pp. 3451–3459, 2006.
[30]
Z. Shen, J. G. Andrews, and B. L. Evans, “Adaptive resource allocation in multiuser OFDM systems with proportional rate constraints,” IEEE Transactions on Wireless Communications, vol. 4, no. 6, pp. 2726–2737, 2005.
[31]
C. Suh and J. Mo, “Resource allocation for multicast services in multicarrier wireless communications,” IEEE Transactions on Wireless Communications, vol. 7, no. 1, pp. 27–31, 2008.
