An Introduction to 5G

11Data Transmission and Reception

The procedures for data transmission and reception are at the core of the 5G air interface. In this chapter, we will describe how data transmissions are scheduled by means of downlink control information (DCI) on the physical downlink control channel (PDCCH), and how the information is actually delivered using the physical uplink and downlink shared channels. We will also address the transmission of reference signals and uplink hybrid ARQ acknowledgements, and discuss the data rates that the 5G air interface can achieve. The procedures mainly lie in the physical layer, but the higher-level aspects are controlled by the medium access control (MAC) protocol.

11.1 Introduction

11.1.1 Data Transmission Procedure

Most of the data transmissions in 5G take place by means of dynamic scheduling, in which the base station schedules each individual transmission by delivering downlink control information on the PDCCH. Figure 11.1 shows the procedures that are used [1].

Figure 11.1 Data transmission procedures for the downlink and uplink.

Downlink transmissions are triggered by the arrival of downlink data at the gNB distributed unit. That reacts by sending the mobile a downlink scheduling command on the PDCCH (Figure 11.1, step 1), which alerts the mobile to a forthcoming data transmission on the physical downlink shared channel (PDSCH) (2). The mobile ...