Boreal Aquatic Ecology

自适应空分多址（SDMA）被认为是未来4g技术支持的重要先进选项。预计这些先进的天线技术将对无线链路提供的容量和服务质量以及对可用频谱的有效利用产生重大影响。这些系统可以在不相互干扰的情况下同时接入同一重叠覆盖区内的不同用户站。这是通过将增益指向感兴趣的用户站，同时在干扰发射机上放置空值来实现的。近年来，由于OFDM-SDMA系统能够提供频谱效率高的无线服务，类似于CDMA系统，但复杂性/成本较低，研究人员和开发人员对其产生了浓厚的兴趣。SDMA通过在相同的时频资源上复用多个用户，有助于实现高频谱效率。另一方面，OFDM通过在OFDM子载波上并行传输数据，提供廉价、高效的高数据速率服务。另一方面，OFDM-SDMA的高效多用户检测设计仍然面临挑战，该检测允许在可接受的符号误差率（SER）下，在每个子载波上有效分离复用SDMA用户数据。到目前为止，针对OFDM-SDMA应用开发的多用户检测技术主要集中在增强SER性能上。然而，在我们最近的工作中，我们提出了一种容量感知的多输入多输出最大比率组合（MIMO-MRC）方案，该方案比现有的MIMO-MRC系统在OFDM-SDMA应用中表现出更好的系统容量和SER性能。因此，在本研究中，我们将研究其他检测方案（如MMSE和MLSE/MLD方案）的容量感知版本。这些计划的检测准则会包括直接提升系统容量，以方便在宽频无线网络上进行部署。然后将开发选定方案的硬件原型，作为向感兴趣的工业伙伴介绍这些方案的平台。

Adaptive space-division multiple accesses (SDMA) are considered as an important and advanced option supported by the upcoming 4G-enabled technologies. These advanced antenna techniques are expected to have a significant impact on the capacity and service quality provided by wireless links and the efficient use of the available spectrum. These systems can be used to simultaneously access different subscriber stations in the same overlapping coverage area without interfering with each other. This is achieved by directing gain towards subscriber stations of interest while simultaneously placing nulls on interfering transmitters. Recently, researchers and developers have developed keen interests in OFDM-SDMA system because of its ability to provide spectrally efficient wireless services, similar to the CDMA system, but at low complexity/costs. SDMA helps to achieve high spectral efficiency, by multiplexing multiple users on the same time-frequency resources. OFDM on the other hand provides cheap, efficient high data rate services through parallel data transmission on the OFDM subcarriers. On the other hand, there are still challenges facing the design of efficient multi-user detection for OFDM-SDMA that allow effective separation of the multiplexed SDMA user data on each subcarrier, at acceptable symbol error rate (SER). So far, existing efforts in developing multi-user detection techniques for OFDM-SDMA applications have focused mainly on the SER performance enhancements. In our recent works, however, we proposed a capacity-aware multiple-input multiple-output - maximum ratio combining (MIMO-MRC) scheme that exhibits better system capacity and SER performance for the OFDM-SDMA application than the existing MIMO-MRC system. Therefore in this research work, we will investigate the capacity-aware version of other detection schemes such as MMSE and MLSE/MLD schemes. Direct enhancement in system capacity will be incorporated in the detection criterion of these schemes, to facilitate deployments over broadband wireless networks. Hardware prototypes of selected schemes will then be developed to serve as a platform for their introduction to interested industrial partners.