Opportunistic beamforming using dumb antennas
Opportunistic beamforming using dumb antennas
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DOI：
10.1109/tit.2002.1003822
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发表时间：
2002-06-01
影响因子：
2.5
通讯作者：
Laroia, R
中科院分区：
文献类型：
--
作者：
Viswanath, P;Tse, DNC;Laroia, R
多用户分集是无线网络中固有的分集形式，由不同用户之间的独立时变信道提供。通过跟踪用户的信道波动，并在用户的瞬时信道质量接近峰值时将传输调度给用户，从而利用分集效益。分集增益随着波动的动态范围而增加，并且因此在具有小散射和/或慢衰落的环境中受到限制。在这样的环境中，我们建议使用多个发射天线，以诱导大而快的信道波动，使多用户分集仍然可以利用。该方案可以被解释为机会波束成形，我们表明，真正的波束成形增益可以实现时，有足够的用户，即使非常有限的信道反馈是必要的。此外，在蜂窝系统中，该方案还起到机会性地使在相邻小区的用户上产生的干扰归零的作用。我们讨论了在一个完整的无线系统中实现该方案的设计影响。
Multiuser diversity is a form of diversity inherent in a wireless network, provided by independent time-varying channels across the different users. The diversity benefit is exploited by tracking the channel fluctuations of the users and scheduling tran missions to users when their instantaneous channel quality is near the peak. The diversity gain increases with the dynamic range of the fluctuations and is thus limited in environments with little scattering and/or slow fading. In such environments, we propose the use of multiple transmit antennas to induce large and fast channel fluctuations so that multiuser diversity can still be exploited. The scheme can be interpreted as opportunistic beamforming and we show that true beamforming gains can be achieved when there are sufficient users, even though very limited channel feedback is needed. Furthermore, in a cellular system, the scheme plays an additional role of opportunistic nulling of the interference created on users of adjacent cells. We discuss the design implications of implementing this scheme in a complete wireless system.