User scheduling for heterogeneous multiuser MIMO systems : A subspace viewpoint

Yi, Xinping; Au, Edward K.S
"IEEE Transactions on Vehicular Technology", October 2011, Vol 60, N°8


In downlink multiuser multiple-input multipleoutput systems, users are practically heterogeneous. However, many existing user scheduling algorithms are designed with an implicit assumption that users are homogeneous. In this paper, we revisit the problem by exploring the characteristics of heterogeneous users from a subspace viewpoint. With an objective of minimizing interference non-orthogonality among users, three new angular-based user scheduling criteria are proposed. While the first criterion is heuristically determined by identifying the incapability of largest principal angle to characterize subspace correlation and hence the interference non-orthogonality between users, the second and third ones are derived by using, respectively, the sum rate capacity bounds with block diagonalization and the change in capacity by adding a new user into an existing user subset. Aiming at capturing fairness among heterogeneous users while maintaining multiuser diversity gain, two new hybrid user scheduling algorithms are proposed whose computational complexities are only linearly proportional to the number of users. We show by simulations the effectiveness of our proposed user scheduling criteria and algorithms with respect to those commonly used in homogeneous environment.


DOI
Type:
Journal
Date:
2011-08-25
Department:
Communication systems
Eurecom Ref:
3507
Copyright:
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PERMALINK : https://www.eurecom.fr/publication/3507