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Dual-based bounds for resource allocation in zero-forcing beamforming OFDMA-SDMA systems

Diego Perea-Vega, André Girard, Jean-François Frigon

Article (2013)

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We consider multi-antenna base stations using orthogonal frequency-division multiple access and space division multiple access techniques to serve single-antenna users. Some users, called real-time users, have minimum rate requirements and must be served in the current time slot while others, called non real-time users, do not have strict timing constraints and are served on a best-effort basis. The resource allocation (RA) problem is to find the assignment of users to subcarriers and the transmit beamforming vectors that maximize the total user rates subject to power and minimum rate constraints. In general, this is a nonlinear and non-convex program and the zero-forcing technique used here makes it integer as well, exact optimal solutions cannot be computed in reasonable time for realistic cases. For this reason, we present a technique to compute both upper and lower bounds and show that these are quite close for some realistic cases. First, we formulate the dual problem whose optimum provides an upper bound to all feasible solutions. We then use a simple method to get a primal-feasible point starting from the dual optimal solution, which is a lower bound on the primal optimal solution. Numerical results for several cases show that the two bounds are close so that the dual method can be used to benchmark any heuristic used to solve this problem. As an example, we provide numerical results showing the performance gap of the well-known weight adjustment method and show that there is considerable room for improvement.

Uncontrolled Keywords

Resource allocation; OFDMA/SDMA; QoS; Minimum rate constraints; Zero-force beamforming

Subjects: 2500 Electrical and electronic engineering > 2500 Electrical and electronic engineering
2500 Electrical and electronic engineering > 2525 Wireless communication systems
Department: Department of Electrical Engineering
Research Center: GERAD - Research Group in Decision Analysis
Funders: CRSNG / NSERC
Grant number: CRDPJ 335934-06
PolyPublie URL: https://publications.polymtl.ca/3431/
Journal Title: EURASIP Journal on Wireless Communications and Networking (vol. 2013)
Publisher: BioMed Central Ltd
DOI: 10.1186/1687-1499-2013-51
Official URL: https://doi.org/10.1186/1687-1499-2013-51
Date Deposited: 05 Dec 2018 16:55
Last Modified: 23 May 2023 12:47
Cite in APA 7: Perea-Vega, D., Girard, A., & Frigon, J.-F. (2013). Dual-based bounds for resource allocation in zero-forcing beamforming OFDMA-SDMA systems. EURASIP Journal on Wireless Communications and Networking, 2013. https://doi.org/10.1186/1687-1499-2013-51


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