2016/06/07 by de Carvalho, Elisabeth, Björnson, Emil, Sørensen, Jesper H. +2
#FOS: Computer and information sciences #Information Theory (cs.IT) #Networking and Internet Architecture (cs.NI)
paper · doi:10.48550/arxiv.1606.02080
5G wireless networks are expected to support new services with stringent requirements on data rates, latency and reliability. One novel feature is the ability to serve a dense crowd of devices, calling for radically new ways of accessing the network. This is the case in machine-type communications, but also in urban environments and hotspots. In those use cases, the high number of devices and the relatively short channel coherence interval do not allow per-device allocation of orthogonal pilot sequences. This article motivates the need for random access by the devices to pilot sequences used for channel estimation, and shows that Massive MIMO is a main enabler to achieve fast access with high data rates, and delay-tolerant access with different data rate levels. Three pilot access protocols along with data transmission protocols are described, fulfilling different requirements of 5G services.