Chapter 9 mmWave communication enabling techniques for 5G wireless systems: A link level perspective
Millimeter wave (mmWave) communication systems have attracted significant interest regarding meeting the capacity requirements of the future 5G network. The mmWave systems have frequency ranges in between 30 and 300 GHz where a total of around 250 GHz bandwidths are available. Although the available bandwidth of mmWave frequencies is promising, the propagation characteristics are significantly different from microwave frequency bands in terms of path loss, diffraction and blockage, rain attenuation, atmospheric absorption, and foliage loss behaviors. In general, the overall loss of mmWave systems is significantly larger than that of microwave systems for a point to point link. Fortunately, however, the small wavelengths of mmWave frequencies enable large numbers of antenna elements to be deployed in the same form factor thereby providing high spatial processing gains that can theoretically compensate for at least the isotropic path loss. Nevertheless, as mmWave systems are equipped with several antennas, a number of computation and implementation challenges arise to maintain the anticipated performance gain of mmWave systems. Toward this end, this chapter discusses key enabling techniques of the mmWave based 5G network from the link level perspective. The link level performance of the mmWave wireless system depends on a number of factors, including the transmission scheme (i.e. whether we employ beamforming, multiplexing, or both) the approach to identifying the channel, how to design the transmitted signal waveform structure and access strategies. This chapter provides a detailed discussion on these enabling techniques with emphasis on mmWave systems and the resulting link level performances.