Fronthaul design for mmWave massive MIMO

This chapter discusses the fronthaul design for a millimeter-wave (mmWave) massive multiple-input multiple-output (MIMO)-based heterogeneous network (HetNet). The dense small-cell deployment requires cost-effective fronthaul with high capacity to accommodate the 1000-fold increase of cellular capacity for 5G. Against this background, the mmWave massive MIMO-based mesh fronthaul has been attracting increasing interest. Compared with existing fronthaul solutions working at low-frequency bands, the mmWave fronthaul is very compatible with the ultradense deployment of small cells because the fronthaul link can be short (typically 50-200. m) to mitigate the high path loss of mmWave signals and guarantee the line-of-sight link. Moreover, by leveraging the emerging mmWave massive MIMO technique, we can easily realize the mesh fronthaul topology to facilitate the installation and reduce the deployment cost. Additionally, the beamforming techniques of mmWave massive MIMO can make the mesh fronthaul more flexible and intelligent. This chapter will present a survey of the existing fronthaul solutions at first, which will be followed by the market requirement of the fronthaul network for the future 5G HetNet. More importantly, we will present the concept of the mmWave mesh fronthaul network, where some issues including antenna techniques, beamforming design, duplexing protocol, in-band fronthaul, and so on, will be discussed in detail.