users. Naturally, this will lead to an improvement in the sections. As a thorough walk through of WCDMA is resource utilization when several users in a cell receive a topic of its own and beyond the scope of this book, the the same content. As a consequence of the broadcast reader is referred to other books and articles for a de- transmission, user-specific adaptation of the transmission tailed description. WCDMA is a versatile and highly Communications Engineering Desk Reference; ISBN: 9780123746481 Copyright © 2007, Erik Dahlman, Stefan Parkvall, Johan Skold and Per Beming. Published by Elsevier Ltd 2001. All rights reserved CHAPTER 4.6 WCDMA evolution: HSPA and MBMS Rel 4 Rel 5 Rel 6 Rel 7 WCDMA HSPA evolution HSDPA Enhanced Uplink HSDPA - improved downlink Enhanced Uplink - improved MIMO and higher-order modulation packet-data support uplink packet-data support - 28 Mbit/s DL peak data rate - Reduced delays - Reduced delays - 11 Mbit/s UL peak data rate - 14 Mbit/s peak data rate - 5.74 Mbit/s peak data rate Continuous Packet Connectivity - ~3 X R99 capacity - ~2 X R99 capacity - 'Always on' user experience MBMS - Multimedia Broadcast Multicast Services Introduction of (improved) broadcast services ('Mobile TV') Figure 4.6-1 WCDMA evolution. flexible radio interface that can be configured to meet the Finally, the RNCs are connected to the Internet and requirements from a large number of services, but the the traditional wired telephony network through the core focus for the description below is the functionality network. commonly used to support packet-data transmissions. Most modern communication systems structure the The main purpose is to provide a brief background to processing into different layers and WCDMA is no ex- WCDMA to put the enhancements described later on ception. The layered approach is beneficial as it provides into a perspective. a certain structure to the overall processing where each layer is responsible for a specific part of the radio-access functionality. The different protocol layers 