Tài liệu WCDMA Channels pptx

WCDMA Channels 10th Aug 2007 Deepak Logical Channels are not actually channels but rather they can be defined as different tasks performed by the network and the UE at different times. • They describe the type of information to be transferred. • Logical channels are categorized into control channels and traffic channels. • Control channels carry the control plane information • Traffic Channels carry the user plane information Transport channels describes how the logical channels will be transferred, or it can be defined as how and with what characteristics data is transferred over the interface. It comes into two groups: Dedicated Channels Common Channels WCDMA Channels Radio Frame Structure In WCDMA the information is spread over 5MHz band (Wide Bandwidth). There are separate radio channels for both uplink and downlink of 5MHz. One radio frame consist of 38400 chips and 15 slots. The duration of the radio frame is 10ms which have ship rate of 3.84 Mcps. Each slots in the radio frame comprises of 2650 chips. frame #i frame #i+1 timeslot #0 timeslot #1 timeslot #2 timeslot #13 timeslot #14 Radio Frame (10ms) Time Slot (2560*T c ) In uplink and downlink direction, each slot in a radio frame is defined with a code or a set of codes that carries a set of common and dedicated channels called Physical Channel. The information rate of the channel varies from 15 kbps to 1920 kbps for downlink and 30 kbps to 1920 kbps corresponding to available Spreading Factor. In Downlink spreading factor from 256 to 4 and in downlink from 512 to 4. • Physical channels are the transmission media providing platform (radio) through which information is going to be transferred • Physical Channels means different kinds of bandwidths allocated for different purposes, its actually is the physical existence of the Uu interface between UE domain and Access domain. • Physical channel are defined by specific carrier freq, scrambling and channelization code Physical Channel Broadcast Control Channel (BCCH): It broadcast system control information for all mobiles in a cell like Code values in the cell, neighbors information, allowed power levels in downlink direction. Paging Control Channel (PCCH): It transfer paging information in downlink direction. Network page the mobile to discover the UE location or UE in a cell connected state. Common Control Channel (CCCH): Network may have certain tasks which are or may be common to UE in the cell. Its being used in both direction downlink & uplink. The CCCH is also used when UE is accessing a new cell after cell reselection. Dedicated Control Channel (DCCH) When there is dedicated/active connection means RRC connection between the network and the mobile, the control information transferred using DCCH. Its a bi-directional channel. Logical Channel Logical Channel Dedicated Traffic Channel (DTCH): It is used transfer the user data between the network and the UE in both uplink and downlink directions. Common Traffic Channel (CTCH): It is used to transfer the data from one point to all mobiles or a specified group of mobiles. Transport Channels  Transport channels describes how the logical channels to be transferred  Transport channel is defined by how and with what characteristics data is transferred over the interface.  It comes into two groups:  Dedicated Channels  Common Channels Transport Channels  Dedicated Traffic Channels: Dedicated Channel (DCH): It is the channel used to send dedicated control and user data between UE and the network in both uplink & downlink directions Enhanced Dedicated Channel (E-DCH): It is a enhanced uplink transport channel.  Common Transport Channel : Random Access Channel (RACH): It is used to send a control information from UE in the uplink direction. Also may carry short user packets. Common Packet Channel (CPCH): Its an uplink shared channel used for packet data. Several UE can use the same channel for data transfer. Transport Channels Forward Access Channel (FACH): It is a downlink common channel used to send small amounts of control and user data. Downlink Shared Channel (DSCH): It is common channel used to send dedicated control and user data. Broadcast Channel (BCH): It broadcast system information in the downlink direction for all mobile stations in a cell. Paging Channel (PCH): It’s a downlink common channel used to send paging notification messages. Dedicated Channel (DCH) It is a channel that is used to send dedicated control and user data between the UE and the network in both directions. Physical Channels  In Uplink there are both dedicated and common physical channels. Dedicated Channels: Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) Common Channels: Physical Random Access Channel Physical Common Packet Channel [...]... be sent through logical layer via different channels in the transport layer •And also one transport channel can be sent via different physical channels •These selection of channels in the transport and physical layer depends on the data itself and radio resource management and its parameters Transport Channels DCH E-DCH RACH BCH FACH PCH HS-DSCH Physical Channels Dedicated Physical Data Channel (DPDCH)... 1 radio frame: T f = 10 ms Slot #i Subframe #3 Slot #14 Subframe #4 Physical Channels Dedicated Physical Data Channel Each radio link may have no DPDCHs or several DPDCHs  Spreading factor for the DPDCH can be between 256 and 4  DPCCH & DPDCH are time – multiplexed in downlink but uplink these are I/Q modulation Physical Channels  Physical Random Access Channel (PRACH) It carries the Random Access... part radio frame T RACH = 10 ms Slot #14 Physical Channels  Physical Common Packet Channel (PCPCH) It carries Common Packet Channel (CPCH Transport Channel) The access transmission consists of Access Preambles (AP), one collision Detection Preamble (CDP), a DPCCH Power Control Preamble (PCP) and message Check out the Structure from ECE book Physical Channels Downlink Dedicated Channel  In downlink... Tslot = 2560 chips, 10*2k bits (k=0 7) Slot #0 Slot #1 Slot #i One radio frame, Tf = 10 ms Slot #14 DPCCH + DPDCH Physical Channels Common Pilot Channel It has pre-defined bit sequence transmitted with a bit rate of 30 Kbps (Fixed Scrambling code 256) CPICH is divided into pilot channels: Primary Common Pilot Channel (P-CPICH) Secondary Common Pilot Channel (S-CPICH) Reason for low bit rate as it is... SCH Physical Channels Secondary Common Control Physical Channel (S-CCPCH) It has variable bit rate from 30kbps to 1,920 kbps There are data bits, pilot bits and optional TFCI bits It is transmitted only to smaller are of the cell TFCI NTFCI bits Data Ndata1 bits Pilot Npilot bits Tslot = 2560 chips, 20*2k bits (k=0 6) Slot #0 Slot #1 Slot #i 1 radio frame: Tf = 10 ms Slot #14 Physical Channels The...Physical Channels Dedicated Physical Control Channel For each radio link, there is one DPCCH, it carries control information like  Pilot bits (used to support channel estimation at rake receiver)  Transmit Power Control (TPC) commands (Used power control)  Feedback information (FBI) needed with transmit diversity  Transport Format Combination Indicator (TFCI) Spreading factor is always 256 Physical Channels. .. used SF256 •A S-CPICH may scrambled with primary or secondary scrambling code •There may be zero, one or several S-CPICH per cell •A S-CPICH transmitted over the entire cell or part of the cell Physical Channels Primary Common Control Physical Channel (P-CCPCH) It has fixed bit rate of 30 Kbps (Fixed Scrambling code 256) There are no TPC, Pilot bits and first 256 chips of the slot are used for the primary... physical random access procedure is initiated Preamble Preamble Preamble 4096 chips Preamble 4096 chips Message part 10 ms (one radio frame) Preamble Preamble Message part 20 ms (two radio frames) Physical Channels RACH Preamble Part Each preamble is of length 4096 chips and consist of 256 repetitions of a signature of length 16 chips RACH Message Part The 10 ms message part spilt into 15 slots each length... P-CCPCH and S-CCPCH the transport channel mapped on this can only have fixed predefined transport format combination and in case S-CCPCH support multiple transport format combination using TFCI Physical Channels Synchronization Channel This channel used in the cell search procedure It is divided into the Primary Synchronization and Secondary Synchronization Channel  Primary Synchronization Channel It... slot, based on the scrambling code group and the slot number Slot #0 Primary SCH Secondary SCH acp i,0 acs Slot #1 acp Slot #14 acp i,1 i,14 acs acs 256 chips 2560 chips One 10 ms SCH radio frame Physical Channels Physical Downlink Shared Channel (PDSCH) It is used for data transmission by one or-several simultaneous users in the downlink direction CD/CA-ICH The collision Detection Assignment Indicator . transferred. • Logical channels are categorized into control channels and traffic channels. • Control channels carry the control plane information • Traffic Channels. interface. It comes into two groups: Dedicated Channels Common Channels WCDMA Channels Radio Frame Structure In WCDMA the information is spread over 5MHz band