From the course: 4G LTE: Architecture, Protocols, Call Flows, KPIs, Optimization, Performance Analysis

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LTE physical layer (Layer 1) overview

LTE physical layer (Layer 1) overview

From the course: 4G LTE: Architecture, Protocols, Call Flows, KPIs, Optimization, Performance Analysis

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LTE physical layer (Layer 1) overview

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Let's dive into the physical layer or layer 1 of 4G technology. In this layer, any resource that needs to be allocated is mapped within a grid of time and frequency. Think of frequency domain as your y-axis and time domain as your x-axis. In the time domain, we have OFDM symbols. For this example, we are looking at 1.4 MHz channel bandwidth, which defines number of subcarriers. Now, within single 10 Ms. frame, we have 10 subframes, each 1 Ms. long. We are going to zoom in on the very first subframe, which contains 14 OFDM symbols. As we know, primary and secondary synchronization signals, which are PSS and SSS, are always located here in the first subframe. Along with them we have broadcast channel plus other signals and channels which are allocated within this time frequency grid. It is important to understand the functionalities of these channels and signals in more detail starting with the synchronization signals PSS and SSS. They are the key signals for cell search and downlink…

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