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摘要
随着现代社会对无线通信的需求不断扩大,人们对无线通信速率和质量的要求也不断提高。而无线信道中多径衰落是限制无线通信速率和质量提高的一个主要因素,因此,人们提出了一些方法来对抗无线通信中的多径衰落,其中分集是一个行之有效的方法。近年来,研究表明一种典型的空间分集技术——多输入多输出(MIMO)技术对无线通信性能有很大的改善,它不仅能够提高通信的可靠性还能够提高通信的有效性。
但是,由于收到移动终端体积,功率,天线位置设置等因素的限制,MIMO很难直接在实际系统应用。Sendonaris等人受到中继信道的启发提出了协作分集的概念,协作分集中具有信号处理技术的两个用户通过共享对方的天线来传输数据,因此它在每个用户只有一根天线的多用户通信系统中也能提供发射分集。
本文首先对移动通信中广泛使用的分集技术、多输入多输出技术,协作分集技术进行了介绍。
其次本文讨论了协作时机的选择,简单介绍了协作分集中的伙伴选择算法,并进行了分析比较。
最后本文提出了一种基于阴影衰落相关性的伙伴选择方案,对其中的模型的性能分析,并进行了仿真。
关键词:分集技术;MIMO;伙伴选择;阴影衰落;相关性
Abstra
ct
With the increasing demands of munication survive, people needs wireless transmission with higher speed and better quality. Signal fading arising from multipath propagation is the main problem to improve speed and quality of wireless transmission; so many methods are introduced to mitigate the impairment of multipath fading among which diversity technique is one of most useful ways to conquer multipath fading. In recent years, multiple-input multiple-output (MIMO) technique as a typical space diversity technique has been shown to be significantly beneficial for munication, as it can offer both an increase in reliability also an increase in rate.
However, MIMO is hardly implemented to real system directly, due to the physical constrains of mobile unit, such ad size, power cost and settings of multiple antennas, thus, the idea of cooperation diversity motivated by relay channel is proposed by Sendonaris. To send information using both of their antennas, so it provides transmit diversity even when each mobile user is set with single antenna in multiple munication system.
Firstly, this paper introduces the diversity techniques, MIMO techniques, cooperative diversity techniques which are widely used in works.
Secondly, this paper discusses the cooperation opportunity choice, briefly introduces the cooperative diversity in partner selection algorithm, analysis parison are made.
Finally, this article proposed one kind based on the correlation of partner selec