WCDMA Air Interface Fundamentals

W-CDMA Air Interface Fundamentals : 

Lucent Technologies Proprietary 1 W-CDMA Air Interface Fundamentals Prepared By: Rupy Sikka E-mail: Rsikka@lucent.com Ph: +1 (630) 2240 192

OBJECTIVES : 

Lucent Technologies Proprietary 2 OBJECTIVES Describe the requirements and drivers behinds the W-CDMA Air Interface. List the layers UMTS radio Air Interface protocol stack and the responsibility of each layer UMTS Channel Types and their purpose Gain understanding of UMTS Modes: FDD and TDD Protection in UMTS:Describe the forward error correction employed by UMTS Air interface Channelizations in UMTS Source Identification: Scrambling codes/Gold Codes

W-CDMA OVERVIEW-ARCHITECTURE : 

Lucent Technologies Proprietary 3 W-CDMA OVERVIEW-ARCHITECTURE Iu-CS Iu-PS PDN/ Internet PSTN Core Network UTRAN

WCDMA OVERVIEW-UTRAN FUNCTIONS : 

Lucent Technologies Proprietary 4 WCDMA OVERVIEW-UTRAN FUNCTIONS UTRAN Functions: Overall System Access Control Security and Privacy Handover Radio Resource Management and Control RNC Functions: Intra UTRAN Handover Frame Synchronization Radio Resource Management: Radio Bearer Control Outer Loop Power Control Radio Resource Allocation

UTRAN FUNCTIONS : 

Lucent Technologies Proprietary 5 UTRAN FUNCTIONS Node B Termination of Iub Interface from RNC Conduct Radio Environment Survey (BER estimate, Rx signal strength etc..) Inner Loop Power Control Open loop power control Radio Channel Coding/decoding Mapping of coded composite transport channels on physical channel modulation and spreading/dispreading of physical channels Frequency and time Synchronization Error detection on transport channels and indication to higher layers Termination of Uu interface from the UE etc..

3G SERVICES : 

Lucent Technologies Proprietary 6 3G SERVICES

3G CHARACTERISTICS - Asymmetric : 

Lucent Technologies Proprietary 7 3G CHARACTERISTICS - Asymmetric

3G CHARACTERISTICS– Concurrent Services : 

Lucent Technologies Proprietary 8 3G CHARACTERISTICS– Concurrent Services

3G CHARACTERISTICS – ALWAYS “ON” : 

Lucent Technologies Proprietary 9 3G CHARACTERISTICS – ALWAYS “ON”

W-CDMA INTERFACE : 

Lucent Technologies Proprietary 10 W-CDMA INTERFACE

SPECTRUM FOR UMTS : 

Lucent Technologies Proprietary 11 SPECTRUM FOR UMTS

UMTS MODES : 

Lucent Technologies Proprietary 12 UMTS MODES

UMTS RADIO PROTOCOL STACK : 

Lucent Technologies Proprietary 13 UMTS RADIO PROTOCOL STACK Layer-1 Layer-2L Layer-2U Layer-3 OSI

RADIO PROTOCOL STACK FUNCTIONS : 

Lucent Technologies Proprietary 14 RADIO PROTOCOL STACK FUNCTIONS Physical Layer Functions (Layer-1) Forward error correction, coding,interleaving Measurements Soft handover execution Multiplexing/mapping of services on dedicated physical code channels Modulation, spreading, demodulation, dispreading of physical channels Frequency and time synchronization Fast closed-loop power control RF processing MAC Layer Function (Layer-2L) Selection of appropriate transport format Service multiplexing on RACH, FACH and dedicated channels Scheduling Access resolution on RACH Contention resolution on RACH etc..

RADIO PROTOCOL STACK FUNCTIONS : 

Lucent Technologies Proprietary 15 RADIO PROTOCOL STACK FUNCTIONS RLC Functions (Layer-2U): Segmentation and assembly Transfer of user data Error correction through retransmission optimized for physical layer Sequence integrity Flow control PDCP Function (Layer-2U) Service specific. Exists only in the User Plane and only for services from PS domain. Contains compression methods needed for better spectral efficiency RRC Functions: Broadcast of system information Radio Resource handling Control of requested QOS UE measurements reporting and control of the reporting

W-CDMA Channel Architecture : 

Lucent Technologies Proprietary 16 W-CDMA Channel Architecture

OBJECTIVE : 

Lucent Technologies Proprietary 17 OBJECTIVE UMTS W-CDMA Channels Structure Map channels to radio interface protocol stack

CHANNELS OVERVIEW : 

Lucent Technologies Proprietary 18 CHANNELS OVERVIEW

Gift ANALOGY : 

Lucent Technologies Proprietary 19 Gift ANALOGY

Channel Overview Cont… : 

Lucent Technologies Proprietary 20 Channel Overview Cont…

UMTS RADIO INTERFACE CHANNELS : 

Lucent Technologies Proprietary 21 UMTS RADIO INTERFACE CHANNELS

LOGICAL CHANNELS : 

Lucent Technologies Proprietary 22 LOGICAL CHANNELS Traffic Channels - Dedicated Traffic Channel (DTCH) - Common Traffic Channel (CTCH) Control Channels - Dedicated Control Channel (DCCH) - Common Control Channel (CCCH) - Broadcast Control Channel (BCCH) - Paging Control Channel (PCCH)

TRANSPORT CHANNELS : 

Lucent Technologies Proprietary 23 TRANSPORT CHANNELS Dedicated Channels - Dedicated Channel (DCH) Common Channels - Random Access Channel (RACH) - Forward Access Channel (FACH) - Broadcast Channel (BCH) - Paging Channel (PCH) - Common Packet Channel (CPCH) - Downlink Shared Channel (DSCH) (CPCH & DSCH are optional channels and are not supported in Lucent’s initial release)

PHYSICAL CHANNELS : 

Lucent Technologies Proprietary 24 PHYSICAL CHANNELS Uplink Dedicated Channels Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) Common Channels Physical Random Access Channel (PRACH) Physical Common Packet Channel (PCPCH) Downlink Dedicated Channel Dedicated Physical Channel (DPCH) Common Channels Common Pilot Channel (CPICH) Primary Common Control Physical Channel (P-CCPCH) Secondary Common Control Physical Channel(S-CCPCH) Synchronization Channel (SCH) Physical Downlink Shared Channel (PDSCH) Acquisition Indication Channel (AICH) Page Indication Channel (PICH)

UMTS RADIO CHANNEL MAPPING : 

Lucent Technologies Proprietary 25 UMTS RADIO CHANNEL MAPPING

W-CDMA PHYSICAL LAYER PROCESSING : 

Lucent Technologies Proprietary 26 W-CDMA PHYSICAL LAYER PROCESSING

W-CDMA PHYSICAL LAYER PROCESSING : 

Lucent Technologies Proprietary 27 W-CDMA PHYSICAL LAYER PROCESSING

W-CDMA PHYSICAL LAYER PROCESSING : 

Lucent Technologies Proprietary 28 W-CDMA PHYSICAL LAYER PROCESSING Protecting Data/User Information: Forward error correction mechanism are applied to allow adding information to the data streams enabling receiver to correct the errors during decoding process. Achieved by digital coding techniques such as: Convolution coding: Can use ½ or 1/3 rating coders. Used for services 19.2Kbps or less e.g. Voice Turbo Coding: Uses two convolution coder working in parallel. Turbo coder defined as 1/3 rate. Additional processing relative to convolution coder. Added delay due to additional processing makes it perfect for non real-time services such as WEB browsing. Used for services data rate 19.2Kbps or higher. Interleaving: Reorder original coded data streams to help error correction

W-CDMA PHYSICAL LAYER PROCESSING : 

Lucent Technologies Proprietary 29 W-CDMA PHYSICAL LAYER PROCESSING Channel Separation Uses OVSF codes OVSF is applied to achieve 3.84Mcps fixed channel rate Source Identification Scrambling codes are used for Node-B and UE identification The set of scrambling codes are known as Gold codes 2-24 Gold codes for UL (UE) 512 are assigned for DL(Node-B)