Chapter 2
UMTS Long-Term Evolution
This chapter provides an overall picture of the Long-Term Evolution (LTE) architecture, as well as a more detailed description of the Physical (PHY) and Medium Access Control (MAC) layers, of which a good knowledge is needed in order to understand the results presented in the following chapters of this book.
2.1 LTE Overview
2.1.1 Requirements
In its Rel'8, LTE was standardized by the 3rd Generation Partnership Project (3GPP) as the successor of the Universal Mobile Telecommunications System (UMTS). LTE was designed from the start with the assumption that all of the services would be packet switched rather than circuit switched, thus continuing the trend set from the evolution of Global System for Mobile communications (GSM), to General Packet Radio Service (GPRS), Enhanced Data Rates for Global system for mobile communications Evolution (EDGE), UMTS, and High-Speed Packet Access (HSPA). During this evolution, the focus has been seen to be moving towards providing ubiquitous availability of broadband communications, as well as the classical voice/text communication capabilities. From the early mobile packet services, not only has throughput been dramatically increased, but also latency has been greatly decreased. Early Second-Generation (2G)-based systems, such as GPRS, were able to offer data transfer rates in the order of 10 kbit/s. In its latest current iteration, ...
