Enhanced opportunistic beamforming for Jakes-correlated fading channels
Enhanced opportunistic beamforming for Jakes-correlated fading channels
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DOI：
10.1109/its.2006.4433422
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发表时间：
2006-09
期刊：
影响因子：
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通讯作者：
Iuri R. Baran;B. Uchôa-Filho
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文献类型：
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作者：
Iuri R. Baran;B. Uchôa-Filho
在多用户通信系统中，所有用户都可以估计其瞬时信噪比（SNR）并将该信息发送到基站（BS），基站（BS）进而决定数据分组应该发送到哪个用户。对于大量用户，不同用户看到的信道条件独立地变化，因此，很可能在任何一个时隙，调度器将找到至少一个用户，其信道处于有利条件（大SNR），产生所谓的多用户分集。在衰落信道中，其中信道的波动动态是有限的，可以使用在BS处采用多个天线的机会波束成形（OBF）。通过随机改变天线增益（功率和相位），在衰落信道中引起更快和更大的波动，OBF实现多用户分集。在本文中，我们提出了一种增强的OBF，以提高整体吞吐量。通过在BS处保存每个用户的天线增益序列，沿着相应的SNR，只要信道时间相干性是显著的，所提出的系统就可以为所选择的用户采用存储器中最适当的天线增益，而不是如在原始OBF方法中那样采用当前增益。Jakes相关衰落信道的计算机仿真结果表明，良好的吞吐量性能。此外，新方法只需要BS更新，便于采用。
In multiuser communication systems all users can estimate their instantaneous signal-to-noise ratio (SNR) and send this information to the base station (BS), which in turn decides to which user a data packet should be sent. For a large number of users, the channel conditions seen by different users vary independently and, consequently, it is likely that at any one time slot the scheduler will find at least one user whose channel is in favorable conditions (large SNR), yielding what is called multiuser diversity. In fading channels, where the fluctuation dynamics of the channel are limited, opportunistic beamforming (OBF) which employs multiple antennas at the BS can be used. By varying the antenna gains (power and phase) in a random manner, to induce faster and larger fluctuations in fading channels, OBF achieves multiuser diversity. In this paper we propose an enhancement of OBF to improve the overall throughput. By saving at the BS the sequence of antenna gains for each user, along with the corresponding SNRs, for as long as the channel time-coherence is significant, the proposed system can adopt for the selected user the most appropriate antenna gain in the memory, rather than the current gain, as in the original OBF approach. Computer simulation results for the Jakes-correlated fading channels indicate a favorable throughput performance. Moreover, the new approach requires only BS updates, facilitating its adoption.