Channel Structure and Function :Channel Structure and Function ZTE University TD&W&PCS BSS Course Team


Objectives :Objectives At the end of this course, you will be able to master: Classification of channels Structure and Function of channels


Content :Classification of channels Structure and Function of channels Physical layer procedure Content


Channel Type :Channel Type Physical channel Transport channel Logical channel Classification of channels


Concept of channel :Concept of channel PHY layer MAC layer RLC layer Transport channel Physical channel Logical channel L1 L2 Classification of channels


Channel Type :Channel Type Logical channels: Describe what is transported (i.e., the types of information to be transmitted) Transport channels: Describe how the logical channels are to be transmitted Physical channels: Represent the “transmission media” providing the platform through which the information is actually transferred Classification of channels


Protocol stack of the Uu interface :Protocol stack of the Uu interface Classification of channels


Logical Channels :Logical Channels Control Channel (CCH) Broadcast Control Channel (BCCH) Paging Control Channel (PCCH) Dedicated Control Channel (DCCH) Common Control Channel (CCCH) Traffic Channel (TCH) Dedicated Traffic Channel (DTCH) Common Traffic Channel (CTCH) Classification of channels


Transport Channel :Transport Channel Random Access Channel (RACH) Broadcast Channel (BCH) Paging Channel (PCH) Forward Access Channel (FACH) Common Packet Channel (CPCH) Common Transport Channels Dedicated Transport Channels Downlink Shared Channel (DSCH) Dedicated Channel (DCH) Classification of channels


Physical Channel :Physical Channel Classification of channels


Mapping relationship :Logic Channel Mapping relationship Classification of channels


Mapping relationship :Mapping relationship Transport Channels DCH RACH CPCH BCH FACH PCH DSCH Physical Channels Dedicated Physical Data Channel (DPDCH) Dedicated Physical Control Channel (DPCCH) Physical Random Access Channel (PRACH) Physical Common Packet Channel (PCPCH) 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) Classification of channels


Content :Classification of channels Structure and Function of channels Physical layer procedure Content


WCDMA frame structure :WCDMA frame structure Structure and Function of channels


Physical Channels(1) :Physical Channels(1) The physical channel is in a 3-layer structure by the time: Superframe One superframe lasts 720ms, and consists of 72 radio frames. radio frame One radio frame has a period of 10ms, and comprises 15 timeslots with the same length. Corresponding to 38400 chips, it is a basic unit of the physical layer. Timeslot A timeslot is a unit composed of a bit domain, corresponding to 2560 chips. The bit number and structure of a timeslot depends on the specific type of the physical channel. Structure and Function of channels


Physical Channels(2) :Physical Channels(2) The frame structure of the physical channels is shown: Structure and Function of channels


Uplink physical channel :Uplink physical channel 2 UL Dedicated physical channel（DPDCH and DPCCH） 2 UL Common physical channel（PRACH and PCPCH） Structure and Function of channels UL Common physical channel UL Dedicated physical channel Dedicated physical Control channel DPCCH Dedicated physical data channel DPDCH Physical random Access channel PRACH Physical common Packet channel PCPCH


Slide 18:Structure and Function of channels Uplink Dedicated physical channel


PRACH :PRACH Physical Random Access Channel PRACH consists preamble part and message part Random access transmit 1or more 4096 chips length preambles and 10ms or 20ms length message part. Structure and Function of channels


Slide 20:Physical Random Access Channel 10ms message part is split into 15 timeslots, each timeslot consists of 2560chips. Each timeslot includes data part and control part. They are transmitted in parallel . Data part :SF=32~256 , control part: SF=256. Structure and Function of channels PRACH


Downlink physical channel :Downlink physical channel DL physical channel include Dedicated physical channel、1 Shared physical channel and five Common control channels. Structure and Function of channels DPCH SCH CPICH PICH AICH CCPCH PDSCH DL common physical channel


Slide 22:Structure and Function of channels Downlink dedicated physical channel


Slide 23:Structure and Function of channels CPICH


CPICH :CPICH There is 2 types of CPICH:P-CPICH and S-PICH P-CPICH: P-CPICH of different cell uses the same Cch,256,0 OVSF code to spread ,the bit rate of P-CPICH is also fixed. The P-CPICH is scrambled by the primary scrambling code. There is one and only P-CPICH per cell. The P-CPICH is broadcast over the entire cell. it is used to search cell primary scrambling code during cell selection procedure. And it is also used for measurement and estimation during handover, cell selection and cell re-selection. S-CPICH: A arbitrary channelization code of SF=256 is used for the S-CPICH. A S-CPICH is scrambled by either the primary or a secondary scrambling code. There may be 0,1 or several S-CPICH per cell. A S-CPICH may be transmitted over the entire cell or part of the cell. It is may be a phase reference for a dl DPCH, but it is decided by high layer signalling. Structure and Function of channels


Slide 25:Structure and Function of channels P-CCPCH


SCH (1) :SCH (1) The Synchronization Channel (SCH) is a downlink signal used for cell search. The SCH consists of two sub channels, the Primary and Secondary SCH. The 10 ms radio frames of the Primary and Secondary SCH are divided into 15 slots, each of length 2560 chips. Structure of synchronization channel Structure and Function of channels


SCH (2) :SCH (2) P-SCH The Primary SCH consists of a modulated code of length 256 chips. The modulated code need not spreading and scrambling. The primary synchronization code (PSC) is transmitted once every slot The PSC is the same for every cell in the system. S-SCH The Secondary SCH consists of repeatedly transmitting a length 15 sequence of modulated codes of length 256 chips. the Secondary Synchronization Codes (SSC), transmitted in parallel with the Primary SCH. Each SSC is chosen from a set of 16 different codes of length 256. This sequence on the Secondary SCH indicates which of the code groups the cell's downlink scrambling code belongs to. Structure and Function of channels


Slide 28:Structure and Function of channels S-CCPCH


PICH :PICH PICH carries PI（Page Indication），SF=256，radio frame=10ms，consists 300bits，288 bits for paging indication，12 bits Tx Off。 PICH relates to S-CCPCH which mapping to PCH。 Structure and Function of channels


Content :Classification of channels Structure and Function of channels Physical layer procedure Content


Cell search procedure (1) :Cell search procedure (1) The cell search is typically carried out in three steps: Step1: Slot synchronization During the first step of the cell search procedure the UE uses the SCH's primary synchronization code to acquire slot synchronization to a cell. This is typically done with a single matched filter (or any similar device) matched to the primary synchronization code which is common to all cells. The slot timing of the cell can be obtained by detecting peaks in the matched filter output. Physical layer procedure


Cell search procedure (2) :Cell search procedure (2) Step2: Frame synchronization and code-group identification During the second step of the cell search procedure, the UE uses the SCH's secondary synchronization code to find frame synchronization and identify the code group of the cell found in the first step. This is done by correlating the received signal with all possible secondary synchronization code sequences, and identifying the maximum correlation value. Since the cyclic shifts of the sequences are unique the code group as well as the frame synchronization is determined. Physical layer procedure


Cell search procedure (3) :Cell search procedure (3) Step3: Scrambling-code identification During the third and last step of the cell search procedure, the UE determines the exact primary scrambling code used by the found cell. The primary scrambling code is typically identified through symbol-by-symbol correlation over the CPICH with all codes within the code group identified in the second step. After the primary scrambling code has been identified, the Primary CCPCH can be detected and the system- and cell specific BCH information can be read. Physical layer procedure


Cell search procedure :Cell search procedure Physical layer procedure


Summary of the process :Summary of the process Physical layer procedure


Exercise :Exercise pls write down the 3 type of channel. and describe their category. One radio frame has a period of ( )ms, and comprises( ) timeslots with the same length. Corresponding to ( ) chips, it is a basic unit of the physical layer. pls describe the main function of each physical channel. pls describe the cell search procedure.