After a mobile switches on, it runs a low-level acquisition procedure so as to identify the nearby LTE cells and discover how they are configured. In doing so, it receives the primary and secondary synchronization signals, reads the master information block from the physical broadcast channel and reads the remaining system information blocks from the physical downlink shared channel. It also starts reception of the downlink reference signals and the physical control format indicator channel, which it will need throughout the process of data transmission and reception later on. In this chapter, we begin by summarizing the acquisition procedure and then move to a discussion of the individual steps.
The most important specification for this chapter is the one for the physical channel processor, TS 36.211 . The system information blocks form part of the radio resource control protocol and are defined in TS 36.331 .
The acquisition procedure is summarized in Table 7.1. There are several steps. The mobile starts by receiving the synchronization signals from all the nearby cells. From the primary synchronization signal (PSS), it discovers the symbol timing and gets some incomplete information about the physical cell identity. From the secondary synchronization signal (SSS), it discovers the frame timing, the physical cell identity, the transmission mode (FDD or TDD) and the cyclic prefix duration (normal or extended).