Spatial Modulation

多天线技术可以显著提高链路频谱效率，这是公认的。然而，大多数使用多天线的技术需要复杂的算法，以消除信道间干扰（ICI），这源于空间复用系统中的同时传输。这使得实际实现困难，特别是在移动的站中，因为必要的数字信号处理需要大量的能量。然而，由于MIMO技术的明显优势，它必须是一个明确的研究目标，以开发新的方法来多天线传输，以减轻实际的限制，同时保留的关键优势。在这里，我们介绍这种全新的方法，它完全避免ICI，同时仍然允许利用空间复用增益。基本原理是，与QAM（正交幅度调制）等数字调制方案类似，将发射机处的多天线阵列视为空间星座图。如在QAM中那样，其中每个星座点对应于特定信息序列（符号），每个天线对应于唯一的信息序列，并且如果输入信息序列与该序列匹配则被激活。因此，天线的位置携带信息。换句话说，单值信号（例如，从天线阵列的天线发射的纯正弦频率载波信号）传达实际信息，只要接收器能够检测实际信号源自何处（检测发射信号能量的实际天线）。隐式信息传输的新的基本原理，在无线通信系统中的几个关键的研究领域，如数字调制，在发射机和接收机的信号处理，链路和系统容量评估和无线系统操作的影响。例如，天线的位置隐含地传递信息这一事实使得对这种系统中的信道容量的调查势在必行。此外，它为一类新的自适应调制算法开辟了道路，该算法考虑了空间星座图，有效地产生了三维自适应调制算法（如在最先进的数字调制中使用的复信号平面加上空间星座域）。此外，需要对传统通信系统进行调整，例如在接收机处添加新的逻辑块，即天线检测。这种天线检测的算法，给定的各种无线电传播环境，必须开发。这个新的概念也对无线系统的运行有影响。例如，在文献中很好地描述了虚拟天线阵列的概念。例如，这种虚拟天线阵列存在于每个节点配备有一个天线的自组织网络中。多个节点（这些节点的子集）可以被认为是虚拟天线阵列。这个概念现在可以与空间调制的新原理相结合，以减轻ad hoc网络中的多跳负担。在本研究中，将进一步探索发射天线阵列的物理位置携带信息的关键观察/发现。这包括对物理层（链路级）的研究以及对系统级（特别是ad hoc和蜂窝系统）的研究。我们的IEEE Trans. On Vehic。电子乐题为“空间调制”的论文（将于2008年上半年发表）展示了我们在这一主题上的初步工作及其潜力。该提案旨在利用我们的领先地位，进一步发展理论，算法，系统概念以及鲁棒性和低复杂性的实际实现。

It is accepted that multiple antenna techniques can significantly improve link spectral efficiency. However, most of the technologies using multiple antennas require complex algorithms in order to eliminate inter-channel interference (ICI) which stems from simultaneous transmissions in spatial multiplexing systems. This renders the practical implementation difficult, especially in mobile stations, as the necessary digital signal processing requires significant energy. However, due to the clear advantages of MIMO techniques it must be a clear research goal to develop new approaches to multiple antenna transmission in order to mitigate the practical limitations while retaining the key advantages. Here, we introduce such entirely new approach which avoids ICI completely while still allowing for the exploitation of spatial multiplexing gains. The basic principle is that, in analogy to digital modulation schemes such as QAM (quadrature amplitude modulation), the multiple antenna array at the transmitter is considered as a spatial constellation diagram . As in QAM where every constellation point corresponds to a certain information sequence (symbol), every antenna corresponds to a unique information sequence, and is activated if the incoming information sequence matches that sequence. As a consequence, the location of the antenna carries information. In other words, a single valued signal, for example, a pure sinusoidal frequency carrier signal transmitted from an antenna of an antenna array conveys actual information provided that the receiver can detect where the actual signal originated from (detection of the actual antenna that transmitted signal energy). The proposed novel fundamental principle of implicit information transmission has implications on several key research areas in wireless communications systems such as on digital modulation, signal processing at the transmitter and the receiver, link and system capacity evaluation and wireless systems operation. For example, the mere fact that the location of an antenna conveys information implicitly makes an investigation of channel capacity in such systems imperative. Moreover, it opens avenues for a new class of adaptive modulation algorithms which takes into account the spatial constellation diagram , effectively resulting in three-dimensional adaptive modulation algorithms (the complex signal plane as used in state-of-the-art digital modulation plus the spatial constellation domain). Furthermore, adjustments are required to conventional communication systems, such as the addition of a new logical block at the receiver - namely, the antenna detection. Algorithms for such antenna detection, given the various radio propagation environments, have to be developed. The novel concept also has implications on the operation of wireless systems. For instance, the concept of virtual antenna arrays is well described in the literature. Such virtual antenna array, for example, exists in ad hoc networks where every node is equipped with one antenna. Multiple nodes (a subset of such nodes) can be considered as a virtual antenna array. This concept can now be combined with the new principle of spatial modulation to mitigate the multihop burden in ad hoc networks. In this research the key observation/discovery that the physical location of a transmitting antenna array carries information, will be further explored. This includes studies on the physical layer (link level) as well as studies on system level (in particular ad hoc and cellular systems). Our IEEE Trans. On Vehic. Techno. paper entitled Spatial Modulation (to appear in the first half of 2008) showcases our initial work on the topic and its potential. This proposal is to take advantage of our leading position to further develop the theory, algorithms, systems concepts as well as robust and low complexity practical implementations.