Simplified Fair Scheduling and Antenna Selection Algorithms for Multiuser MIMO Orthogonal Space-Division Multiplexing Downlink

Dept. of Electr. & Comput. Eng., Univ. of Alberta, Edmonton, AB
IEEE Transactions on Vehicular Technology (Impact Factor: 2.06). 04/2009; DOI: 10.1109/TVT.2008.925002
Source: IEEE Xplore

ABSTRACT We consider the downlink of a multiuser multiple-input multiple-output (MIMO) system, where the base station and the mobile receivers are equipped with multiple antennas. We propose simplified algorithms for channel-aware multiuser scheduling in conjunction with receive antenna selection for two downlink multiuser orthogonal space-division multiplexing techniques: block diagonalization and successive optimization. The algorithms greedily maximize the weighted sum rate. The algorithms add the best user at a time from the set of users that are not selected yet to the set of selected users until the desired number of users has been selected. To apply the proportional fairness criterion, simplified user scheduling metrics are proposed for block diagonalization and successive optimization. Two receive antenna selection algorithms are also proposed, which further enhance the power gain of the equivalent single-user channel after orthogonal precoding by selecting a subset of the receive antennas that contributes the most toward the total power gain of the channel. A user grouping technique is used to further lower the complexity of the selection algorithms. We compare various multiuser MIMO scheduling strategies that are applied to block diagonalization and successive optimization transmission techniques through simulation. Simulation results demonstrate the effectiveness of the proposed algorithms in ensuring throughput fairness among users. Results also show that when the number of users is large, the proposed scheduling algorithms perform close to the exhaustive search algorithms and previously proposed greedy scheduling algorithms, but with much lower complexity.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Under a given modulation scheme and a target BER (bit error rate) requirement, it is difficult to increase the number of bits transmitted in each symbol (i.e., the rate), since this generally requires a significant increase of transmit power. In this paper, we study how to increase the rate in multiuser multiple-input multiple-output (MU-MIMO) broadcast channels using only bit and power loading, without requiring additional transmit power. To solve this challenging problem, our approach is to carry out a joint design of bit loading and power allocation over all streams, and meanwhile take user and stream selection into account. Specifically, we maximize the total number of bits per symbol (rather than the Shannon capacity) over all selected streams, under a target BER constraint for each stream and a constant total transmit power constraint. To enable flexible user and stream selection as well as achieving a high total rate, we consider OSDM (orthogonal space division multiplexing) rather than BD (block diagonalization) based MU-MIMO broadcast channels. Numerical results show that our proposed joint bit and power loading with OSDM user and stream selection is effective in increasing the total transmission rate without consuming additional resources.
    Communications (ICC), 2012 IEEE International Conference on; 01/2012
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we have presented a joint design of multiuser scheduling and transmit antenna selection for the multiuser MIMO system employing block diagonalization with linear transceivers. Based on these criterions, we have proposed a successive multiuser scheduling scheme. Simulation results show that maximizing global averaged eigenvalues (MGAE) is suitable for multiuser scheduling scheme in term of sum rate capacity. As for the transmit antenna selection schemes, maximizing global minimum eigenvalue (MGME) is preferred at higher SNR and MGAE is suitable at lower SNR.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Channel correlation has the effect to reduce the sum rate and user capacity of multiuser multi-input multi-output (MU-MIMO) systems considerably. In this paper, receive antenna selection is proposed for uplink MU-MIMO system to maximize the sum rate and to maintain high user capacity over correlated Rayleigh fading channel. Two antenna selection criteria are presented to tradeoff the computational complexity and performance. Capacity based selection criterion (CBSC) provides optimal performance at the cost of high complexity compared with the suboptimal norm based selection criterion (NBSC). Simulation results demonstrate and validate the effectiveness of proposed method compared with conventional MU-MIMO systems.
    14th International Symposium on Wireless Personal Multimedia Communications, WPMC 2011, Brest, France, October 3-7, 2011; 01/2011