Cooperative Multicell Zero-Forcing Beamforming in Cellular Downlink Channels

• Published in: IEEE transactions on information theory 2009-07, Vol.55 (7), p.3206-3219
• Main Authors: Somekh, O., Simeone, O., Bar-Ness, Y., Haimovich, A.M., Shamai, S.
• Format: Article
• Language: English
• Subjects: Antenna arrays; Applied sciences; Approximation; Array signal processing; Asymptotic properties; Beamforming; Broadcast channel; Cellular; Channels; Cities and towns; Coding, codes; Communication channels; Context; Degradation; Detection, estimation, filtering, equalization, prediction; distributed antenna array; Downlink; Exact sciences and technology; Fading; fading channels; Information theory; Information, signal and communications theory; Law; Offsets; Performance evaluation; scaling law; Signal and communications theory; Signal to noise ratio; Signal, noise; Similarity; sum-rate capacity; System performance; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Wireless communication; Wyner cellular downlink; zero-forcing beamforming (ZFBF)
• ISSN: 0018-9448; 1557-9654
• DOI: 10.1109/TIT.2009.2021371

In this work, a multicell cooperative zero-forcing beamforming (ZFBF) scheme combined with a simple user selection procedure is considered for the Wyner cellular downlink channel. The approach is to transmit to the user with the ldquobestrdquo local channel in each cell. The performance of this suboptimal scheme is investigated in terms of the conventional sum-rate scaling law and the sum-rate offset for an increasing number of users per cell. We term this characterization of the sum-rate for large number of users as high-load regime characterization, and point out the similarity of this approach to the standard affine approximation used in the high-signal-to-noise ratio (SNR) regime. It is shown that, under an overall power constraint, the suboptimal cooperative multicell ZFBF scheme achieves the same sum-rate growth rate and slightly degraded offset law, when compared to an optimal scheme deploying joint multicell dirty-paper coding (DPC), asymptotically with the number of users per cell. Moreover, the overall power constraint is shown to ensure in probability, equal per-cell power constraints when the number of users per-cell increases.