s communica- tions, services and features (including VHE). Application It represents the application process itself, provided to the end-user. stratum It includes end-to-end protocols and functions making use of ser- vices provided by the home, serving and transport strata and neces- sary infrastructure supporting services and/or value added services. The functions and protocols within the application stratum may adhere to GSM/UMTS standards or may be outside the scope of the UMTS standards. End-to-end functions are applications consumed by users at the edge of/outside the overall network. Authenticated and authorised users may access the applications by using any variety of available user equipment. The UMTS Network and Radio Access Technology: Air Interface Techniques for Future Mobile Systems Jonathan P. Castro Copyright © 2001 John Wiley & Sons Ltd Print ISBN 0-471-81375-3 Online ISBN 0-470-84172-9 THE UTRA PHYSICAL LAYER DESIGN The UTRA design is comprised basically of three parts, i.e. radio aspects corresponding primarily to the physical layer, radio interface aspects incorporating layers two and three, and network aspects inter-working directly with the core network. This chapter describes the UTRA physical layer including both FDD and TDD modes, as well as spreading and modulation, multiplexing and channel coding, and physical layer procedures. SUMMARY OF FEATURES Figure 4.1 illustrates the relationship of the physical layer (L1) and the upper layers (L2-L3). L1 interfaces the Medium Access Control (MAC) sub-layer of L2 and the Radio Resource Control (RRC) portion of L3. L1 offers different transport channels to the MAC and the MAC offers different logical channels to the Radio Link Control (RLC) sub-layer of L2. Thus, there are Service Access Points (SAPs) between the dif- ferent layer/sub-layers. A transport channel is characterized by the way information is transferred over the radio interface. The type of information transferred characterizes a logical channel. Two types of physical channels are defi