Published online by Cambridge University Press: 05 June 2013
As the demand for high-rate wireless services increases, new techniques and architectures have emerged to increase their spectral efficiency and improve their reliability. During the last decade, multiple-input multiple-output (MIMO) or multiple-antenna technology has attracted much attention due to its ability to provide fast and reliable transmission without bandwidth expansion or increase in transmit power. For point-to-point MIMO systems, it has been shown that the capacity of an MIMO channel grows linearly with the minimum number of antennas at both ends . For multi-user systems, MIMO can support space-division multiple access (SDMA) and provide multi-user diversity gain. MIMO has been a key to most modern wireless communication standards such as the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) and LTE-Advanced, Worldwide Interoperability for Microwave Access (WiMAX) and IEEE 802.11n Wireless Fidelity (WiFi).
While the original LTE mainly considered capacity, heterogeneous cellular networks (HCNs), where macrocells are overlaid with low-power nodes (LPNs) such as picocells, femtocells, and relay nodes, have attracted lots of interest in LTE-Advanced to meet the explosive but unequal mobile data traffic demands. On the other hand, due to the scarcity of spectrum, full frequency reuse has been an attractive strategy considered in LTE-Advanced . In conventional homogeneous macrocell cellular networks operating under the principle of single-cell processing (SCP), there is strong intercell interference (ICI), which can be treated as noise and becomes the major challenge that limits system performance in terms of both throughput and fairness. In particular, user equipments (UEs) at the cell edges suffer the most from ICI.