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UTRA Physical Layer November 18 Raul Bruzzone
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Contents (I) Introduction FDD Mode Physical Channel Concept
Downlink Physical Channels Uplink Physical Channels Multiplexing, Coding, Spreading and Modulation Radio Transmission and Reception Procedures Summary November 18 V3.0
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Contents (II) TDD Mode Frame Structures Physical Channels Burst Types
Transport Channels Mapping of Transport Channels on Physical Channels Summary November 18 V3.0
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Introduction November 18 V3.0
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UMTS Terrestrial Radio Access (UTRA) Access Modes
UTRA is able to operate on two access modes: Frequency Division Duplex (FDD) Time Division Duplex (TDD) November 18 Raul Bruzzone
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Frequency Division Duplex (FDD) Time Division Duplex (TDD)
Downlink (fd) Base Station Uplink (fu) In the FDD mode: fd = fu In the TDD mode: fd = fu User Equipment November 18 Raul Bruzzone
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Implementation of FDD and TDD
Receiver Transmitter RF Switch Filter Receiver Filter Transmitter Duplexer Receiver and Transmitter operate simultaneously When the Receiver operates, the Transmitter stops, and vice-versa November 18 Raul Bruzzone
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Frequency Division Duplex
(FDD) Mode November 18 V3.0
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PHYSICAL CHANNEL CONCEPT
The basic Radio Resources are called “Physical Channels”. These channels are characterized by: Spreading Code Carrier Frequency Phase (with reference to the un-modulated carrier: 0 or p/2). This characteristic is only used in the Uplink. November 18 Raul Bruzzone
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PHYSICAL CHANNELS Classification
Physical Channels are classified in: Downlink Uplink November 18 Raul Bruzzone
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DOWNLINK PHYSICAL CHANNELS
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UMTS Downlink Physical Channels (FDD)
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Downlink Dedicated Physical Channel
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Frame Structure November 18 Raul Bruzzone DPCCH DPDCH TFCI Data 1 TPC
Pilot NTFCI bits Ndata1 bits NTPC bits Ndata2 bits N bits pilot 0.625 ms, 20*2 k bits (k=0..6) Slot #1 Slot #2 Slot #i Slot #16 T = 10 ms f Frame #1 Frame #2 Frame #i Frame #72 T super = 720 ms November 18 Raul Bruzzone
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Data Field Specifications
Reference Parameter: k k = 0, 1, 2, 3, 4, 5, 6, 7 Total Quantity of Bits = 20 * 2k k is related to the spreading factor (SF) of the physical channel by means of the expression: Based on the above formula, each time slot may transport a minimum of 20 bits, and a maximum of 1280 bits. Taking into account that the time slot length is ms, the data rate of one downlink DPDCH November 18 Raul Bruzzone
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Data and Control Fields
DPCCH DPDCH TFCI Data 1 TPC Data 2 Pilot NTFCI bits Ndata1 bits NTPC bits Ndata2 bits Npilot bits Note that there are duplicate lines for 16, 32 and 64 kbps, corresponding to the possibilities of including a TFCI field or not. * If no TFCI, then the TFCI field is blank. November 18 3GPP
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Data Communication Efficiency
100 80 60 Efficiency (%) 40 20 Data Rate (Kbps) 16 16 32 32 64 64 128 256 512 1024 2048 FDD mode efficiency is low for low data rates. It varies from 20 to 97.5 % as the data rate increases. Efficiency ranges from 20 to 97.5 % as the data rate increases. November 18 Raul Bruzzone
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Pilot Patterns Yellow Bits may be used for Frame Synchronization.
DPCCH DPDCH TFCI Data 1 TPC Data 2 Pilot NTFCI bits Ndata1 bits NTPC bits Ndata2 bits Npilot bits Yellow Bits may be used for Frame Synchronization. Transmission order is from left to right. Each two-bits pair represents an I/Q pair of QPSK modulation. November 18 3GPP
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Transmit Power Control Field Patterns
DPCCH DPDCH TFCI Data 1 TPC Data 2 Pilot NTFCI bits Ndata1 bits NTPC bits Ndata2 bits Npilot bits November 18 3GPP
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Common Control Physical Channels
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Primary Common Control Physical Channel (PCCPCH)
Used to carry the Broadcast Control Channel (BCH) Fixed rate: 32 Kbps Fixed Spreading Factor: 256 It is not transmitted during the first 256 chips of each Time Slot. This period is left to the Primary and Secondary Synchronization Channels. The BCCH of UMTS is based on the same design principles of the BCCH used in GSM. The high Spreading Factor implies a high Processing Gain and, therefore, high probability of good quality reception in bad propagation conditions. November 18 Raul Bruzzone
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Frame Structure November 18 3GPP
256 chips (Tx OFF) Data 10 bits DATA (Ndata bits) Pilot 8 bits 0.625 ms, 20 bits Slot #1 Slot #2 Slot #i Slot #16 T = 10 ms f Observe that the PCCCH has no TPC nor RI fields. Frame #1 Frame #2 Frame #i Frame #72 T = 720 ms super November 18 3GPP
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Secondary Common Control Physical Channels (SCCPCH)
Applications: To transport the Paging Channel (PCH). To transport the Forward Access Channel (FACH). Number of SCCPCHs depend of Cell traffic November 18 3GPP
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Use of Transport-Format Channel Indicator (TFCI)
There are two types of SCCPCH: With TFCI Without TFCI It is the UTRAN that determines if the TFCI should be transmitted. It is mandatory for the User Equipment to be able to support the TFCI. Spreading factor: SF = 256 / 2k (k = 0…6) Data rates between 32 and 2048 kbps. November 18 3GPP
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Frame Structure November 18 3GPP TFCI DATA (Ndata bits) Pilot
Npilot bits N bits TFCI 0.625 ms, 20*2 k bits (k = 0…6) Slot #1 Slot #2 Slot #i Slot #16 T = 10 ms f Frame #1 Frame #2 Frame #i Frame #72 T = 720 ms super November 18 3GPP
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Secondary Common Control Channel Fields
TFCI DATA (Ndata bits) Pilot Npilot bits N bits TFCI November 18 3GPP
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Differences between Primary and Secondary Common Control Physical Channels
PCCCH has a fixed rate (32 Kbps). SCCCHs can support variable rate, based on the value of the associated Transport-Format Channel Indicator (TFCI) . SCCCHs are only transmitted when there is data to send. PCCCH is transmitted over the whole cell. SCCCHs may be transmitted on narrow lobes pointed to the target UE channel (only valid for a Secondary CCPCH carrying the FACH). November 18 3GPP
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Synchronization Channel (SCH)
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Synchronization Channel (SCH)
It is used for Cell Search. It consists of two sub-channels: Primary Synchronization Channel Secondary Synchronization Channel The PSCH uses a fixed, pre-defined Gold code. November 18 3GPP
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Characteristics of the Primary Synchronization Channel
Transmitted once per Time Slot. Contents is the same in each Time Slot. Aligned in time with the BCCH. Un-modulated. Spreading Factor = 256 November 18 3GPP
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Characteristics of the Secondary Synchronization Channel (SSCH)
It consists of repeatedly transmitting a length = 16 sequence of un-modulated codes of length 256 chips. Each Secondary Synchronization code is chosen from a set of 17 different codes of length 256. The Secondary SCH sequence indicates which of the 32 different code the cell's downlink scrambling code belongs. 32 sequences are used to encode the 32 different code groups each containing 16 scrambling codes. November 18 3GPP
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Synchronization Channel Time Structure
1 Time Frame = 16 Time Slots Primary Synchronization Channel (PSCH) Secondary Synchronization Channel (SSCH) 1 Time Slot = 2560 Chips 256 Chips The same code is used for all bursts of the PSCH SSCH is a sequence of 16 different codes. The SSCH sequence identifies the Cell Group November 18 Raul Bruzzone
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Interleaving of Synchronization Channel and Primary Common Control Channel
Physical Channel (PSCH) Data Pilot Data Pilot Primary Synchronization Channel (PSCH) 256 chips 256 chips 256 chips Secondary Synchronization Channel (SSCH) 2560 chips 2560 chips November 18 3GPP
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Multiplexing of Synchronization Channels
Lower position during 256 chips per slot 1 S SCH c p d i c s S S To IQ modulator DPDCH/DPCCH c ch,1 & CCPCH c scramb c ch,N November 18 ETSI
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Physical Downlink Shared Channel (PDSCH)
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Physical Downlink Shared Channel (PDSCH)
It is the physical channel that supports the Downlink Shared Channel. It is shared by several UE by means of Code Multiplexing. It is always associated with another physical channel. November 18 3GPP
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Physical Shared Channel Control Channel (PSCCCH)
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Physical Shared Channel Control Channel (PSCCCH)
Contains information shared by several UE. Its Control Information field includes TPC to be applied by the UE pool. Detailed structure is still under development. November 18 3GPP
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Physical Shared Channel Control Channel (PSCCCH) Frame Structure
Slot #1 Slot #2 Slot #i Slot #16 Frame #1 Frame #2 Frame #i Frame #72 0.625 ms, 20*2 k bits Pilot N pilot T f = 10 ms super = 720 ms CONTROL INFORMATION November 18 3GPP
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Acquisition Indication Channel (AICH) Page Indication Channel (PICH)
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Acquisition Indication Channel (AICH)
It is a physical channel used to carry Acquisition Indicators (AI) corresponding to the signature of the Random Access Channel Preamble. 16 symbols (1 ms) 4 symbols (0.25 ms) AI empty AS #1 AS #2 AS #i AS #8 One frame (10 ms) AS: Access slot November 18 3GPP
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Page Indication Channel (PICH)
PICH provides Page Indicators (PI) to the User Equipment. One PICH frame has 10 ms length. Each frame comprises 8 access slots. 5, 10 or 20 Page Indicators may be included in an Access Slot. 20 symbols (1.25 ms) AS #1 AS #2 AS #i AS #8 One frame (10 ms) November 18 AS: Access slot 3GPP
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UPLINK PHYSICAL CHANNELS
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UMTS Uplink Physical Channels
Common Dedicated Physical Random Access Channel Uplink Dedicated Physical Data Channels (PRACH) (DPDCH) Fast Uplink Signalling Channel (FAUSCH) This chart shows the classification of UTRA uplink physical channels. Physical Common Packet Channel (PCPCH) November 18 Raul Bruzzone
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Uplink Dedicated Physical Data Channels
Uplink Physical Channels Common Dedicated Physical Random Access Channel Uplink Dedicated Physical Data Channels (PRACH) (DPDCH) Fast Uplink Signalling Channel (FAUSCH) Physical Common Packet Channel (PCPCH) November 18 3GPP
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Frame Structure November 18 3GPP DPDCH DPCCH 0.625 ms, 10*2
DATA Ndata bits DPDCH Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH 0.625 ms, 10*2 k bits (k= 0..6) Slot #1 Slot #2 Slot #i Slot #16 T = 10 ms f There are two types of uplink dedicated physical channels, the uplink Dedicated Physical Data Channel (uplink DPDCH) and the uplink Dedicated Physical Control Channel (uplink DPCCH). The uplink DPDCH is used to carry dedicated data generated at Layer 2 and above, i.e. the dedicated transport channel (DCH). There may be zero, one, or several uplink DPDCHs on each Layer 1 connection. The uplink DPCCH is used to carry control information generated at Layer 1. The Layer 1 control information consists of: Known pilot bits to support channel estimation for coherent detection Transmit power-control (TPC) commands. An optional transport-format combination indicator (TFI). The transport-format combination indicator informs the receiver about the instantaneous parameters of the different transport channels multiplexed on the uplink DPDCH. Feedback mode transmit diversity and site selection diversity. There is one and only one uplink DPCCH on each Layer 1 connection. Frame #1 Frame #2 Frame #i Frame #72 T = 720 ms super November 18 3GPP
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Data Field DATA Ndata bits DPDCH November 18 3GPP
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Distribution of Bits in the Control Fields
Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH November 18 3GPP
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Pilot Patterns Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH Patterns for 5 Bits per Time Slot Patterns are defined for 5, 6, 7 and 8 Pilot Bits per Time Slot. Shadowed bits may be used for Frame Synchronization. November 18 3GPP
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Transport-Combination Format Indicator (TFCI) Field Pattern
Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH This field is optional: UTRAN may request its presence to the User Equipment. If it is present, it is represented by a 32-bits word transmitted in each Frame. The TFCI value may be negotiated between UTRAN and UE on a frame-to-frame basis. Actual values of TFCI are not yet defined. November 18 3GPP
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Feedback Information Pattern
Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH The contents of this field is still under development. November 18 3GPP
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Transmit Power Control Field Patterns
Pilot Npilot bits TFCI NTFCI bits FBI NFBI bits TPC NTPC bits DPCCH November 18 3GPP
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Physical Random Access Channel
Uplink Physical Channels Common Dedicated Physical Random Access Channel Uplink Dedicated Physical Data Channels (PRACH) (DPDCH) Fast Uplink Signalling Channel (FAUSCH) Physical Common Packet Channel (PCPCH) November 18
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General Characteristics
Provides the UE the capability to access the Fixed Network. Access Method is based on the Slotted Aloha principle. Access Time Slots have 1.25 ms offset. Access Time Slots boundaries are referred to the Broadcast Common Control Channel (BCCH) time reference. November 18 Raul Bruzzone
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Access Slots Timing November 18 3GPP
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Random Access Burst Structure
As the length: Preamble + Idle is equal to 1.25 ms (exactly the offset explained in the previous slide) there is no superposition of preambles coming from different UE. This improves the capacity of the BS to differentiate messages coming from different UE. Several Preambles are may precede the Message part. November 18 3GPP
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Preamble Structure Based on 16 Complex Symbols (Signature)
Each Symbol is spread by means of a 256 chips real orthogonal Gold code There are a total of 16 possible Signatures Complex Symbols means that each symbol has a specific I and Q component values. November 18 Raul Bruzzone
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Message Structure Data Data N bits Pilot TFCI Control N bits N bits T
= ms, 10*2 k bits (k=0..3) slot According to the fixed set of spreading factors for the data part, the possible data rates are: SF= 256 Rate= 16 Kbps SF= 128 Rate= 32 Kbps SF= 64 Rate= 64 Kbps SF=32 Rate= 128 Kbps Slot #1 Slot #2 Slot #i Slot #16 Random-access messageT = 10 ms RACH November 18 3GPP
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Data and Control Fields Contents
bits data Pilot TFCI Control N bits N bits pilot TFCI Data Field Control Fields November 18 3GPP
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Fast Uplink Signalling Channel (FAUSCH) Physical Common Packet Channel (PCPCH)
Uplink Physical Channels Common Dedicated Physical Random Access Channel Uplink Dedicated Physical Data Channels (PRACH) (DPDCH) Fast Uplink Signalling Channel (FAUSCH) Physical Common Packet Channel (PCPCH) FAUSCH and PCPCH will be included in the Release 2000 November 18 3GPP
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Multiplexing, Coding, Spreading and Modulation
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Multiplexing of Physical Channels
TC TC TC TC Channel coding + Coding + Coding + optional TC multiplex interleaving interleaving Static rate matching Rate Rate matching matching Inner interleaving Interleaving Interleaving (inter-frame) (optional) (optional) Transport-channel multiplexing Multiplex Dynamic rate matching Rate (uplink only) matching Inner interleaving (intra-frame) Interleaving November 18 3GPP
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UTRA/FDD Transport Channels Coding
Convolutional coding Turbo coding Service-specific coding Different channel coding options are available: * Convolutional Coding is suggested for BER=10-3 services. * Reed Solomon + Outer Interleaving + Convolutional Coding is suggested for BER=10-6 services. * Turbo Coding is an alternative under investigation for the previous case. * Service specific coding is suggested to optimize the data throughput in (for example) voice and video applications. November 18 3GPP
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Downlink Spreading and Modulation (I)
cos( w t) I p(t) DPDCH/DPCCH S P c c sin( ch scramb w t) Q p(t) c : channelization code ch c This scheme shows the signal processing performed on a downlink dedicated channel. It comprises the following stages: Serial to parallel conversion Double spreading (channelization and scrambling) Pulse shaping (by means of root raised cosine filters) I/Q modulation (Armstrong method) : scrambling code scramb p(t): pulse-shaping filter (root raised cosine, roll-off 0.22) November 18 3GPP
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Downlink Spreading and Modulation (II)
Data and Control streams are de-interleaved by a serial-to-parallel conversion. Each output stream is applied to the I and Q paths. I and Q paths are spreaded by a channel-specific code (Channelization Code). I and Q paths are subsequently spreaded by a Cell-specific code (Scrambling Code). Pulse Shaping is applied to reduce spectrum occupancy and Inter-Symbol Interference (ISI) Pulse shaping is performed by Root Raised Cosine filters with 0.22 roll-off factor. The same type of filters are also used in the receiver side. November 18 3GPP
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Uplink Spreading and Modulation (I)
Channelization codes (OVSF) c cos( D w t) c ” scramb I DPDCH c’ (optional) Real p(t) scramb I+jQ c sin( w t) C Q Imag DPCCH * j p(t) c ,c : channelization codes D C c’ : primary scrambling code scramb c’’ : secondary scrambling code (optional) scramb p(t): pulse-shaping filter (root raised cosine, roll-off 0.22) November 18 3GPP
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Uplink Spreading and Modulation (II)
Data information (DPDCH) uses the I-path. Control information (DPCCH) uses the Q-path. Independent spreading codes (Channelization Codes) are used for the I and Q paths. A UE-specific spreading code (Scrambling Code) is subsequently applied. November 18 V2.0Raul Bruzzone
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Radio Transmission and Reception Characteristics
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Basic Characteristics Valid for Region 1 (Europe) and 3 (Asia) *
Frequency Bands: 1920 to 1980 MHz (Uplink) 2110 to 2170 MHz (Downlink) RF Carrier Spacing: 5 MHz RF Channel Raster: 200 KHz Power Control Rate: 1600 Cycles per Second * Region 2 (Americas) is not yet defined. November 18 3GPP
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User Equipment Transmitter Characteristics
This slide presents specifications of the User Equipment. Similar specifications apply to the Base Station (see corresponding standard ). Frequency Stability The UE modulated carrier frequency shall be accurate to within ±0.1 PPM compared to carrier frequency received from the BS. These signals will have an apparent error due to BS frequency error and Doppler shift. In the later case, signals from the BS must be averaged over sufficient time that errors due to noise or interference are allowed for within the above ±0.1 PPM figure. Note: The slide presents only the most relevant specifications. For a more detailed description, refer to the corresponding standard. November 18 3GPP
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User Equipment Receiver Characteristics
A Bit Error Rate (BER) equal or less than must be achieved under the following situations: PCCPCH: Primary Common Control Physical Channel DPCH: Dedicated Physical Channel PN: Pseudo Noise November 18 3GPP
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Procedures November 18 V3.0
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Power Control Procedures
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Uplink Power Control Open Loop Procedure
This Power Control mechanism is used to select the transmission power to be used by the UE in the Random Access Channel (RACH). In order to avoid Rayleigh fading, the ME measures the received power at the Primary CCPCH and makes an average estimate. Path Loss is calculated as the difference between the BS emitted power (whose value is broadcasted in the BCCH) and the measured received power. The level of uplink interference at the BS is also known by the UE because it is broadcasted by the BS in the BCCH. November 18 Raul Bruzzone
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Uplink Power Control Outer Loop Procedure
This procedure is implemented by the UE in order to define the reference for the closed loop mechanism (see next chart). Suitable procedures for estimating the connection quality and consequent target S/I are still under development. November 18 Raul Bruzzone
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Uplink Power Control Closed Loop Procedure
BASE STATION PROCEDURE MOBILE STATION PROCEDURE ESTIMATE RECEIVED DPCCH DECREASE POWER DTPC dB DOWN TPC ? ESTIMATE TOTAL UPLINK RECEIVED INTERFERENCE UP INCREASE POWER DTPC dB No Yes TPC DOWN TPC UP SIREST>SIRTARGET November 18 Raul Bruzzone
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Downlink Power Control Outer Loop Procedure
This procedure is implemented by the BS in order to set the target S/I for the closed loop procedure (see next slide). Suitable procedures for estimating the connection quality and consequent target S/I are still under development. November 18 Raul Bruzzone
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Downlink Power Control Closed Loop Procedure
MOBILE STATION PROCEDURE BASE STATION PROCEDURE DECREASE POWER DTPC dB ESTIMATE RECEIVED DPCCH DOWN TPC ? UP ESTIMATE TOTAL UPLINK RECEIVED INTERFERENCE INCREASE POWER DTPC dB No Yes TPC DOWN TPC UP SIREST>SIRTARGET November 18 Raul Bruzzone
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Cell Search Procedures (I) Initial Cell Search (Attachment)
ACQUIRE Frame Synchronization Timing RECEIVE Primary Synchronization Channel ACQUIRE Base Station Scrambling Code SELECT Strongest Base Station DETECT Primary Common Control Channel RECEIVE Secondary Synchronization Channel This procedure is implemented in the UE in order to select the most appropriate cell to camp on. ACQUIRE Super Frame Synchronization IDENTIFY Base Station Code Group READ Broadcast Control Channel November 18 Raul Bruzzone
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Cell Search Procedures (I) Idle and Active Modes Cell Search
READ Base Stations Priority List SEARCH Base Station See details in next slide These procedures are implemented in the UE during the Idle and Active modes. Reasons for activating this procedure are the following: Due to the movement of the UE or increasing interference in its neighbourhood, it may require to select a new cell with which an acceptable quality communication might be set up. No Base Station Acquired ? Yes END Search November 18 Raul Bruzzone
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Cell Search Procedures (II) Idle and Active Modes Cell Search
Base Station ACQUIRE Frame Synchronization Timing READ Broadcast Control Channel RETURN DETECT Primary Common Control Channel ACQUIRE Super Frame Synchronization November 18 Raul Bruzzone
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Random Access Procedure
SELECT Spreading Factor for Message Part WAIT ESTIMATE Downlink Path Loss ACQUIRE Base Station Synchronization Yes Time-out ? CALCULATE Uplink Transmit Power READ Broadcast Common Control Channel Information No No Received BS ACK ? SELECT (randomly) an Access Slot Time Out is a waiting period for the reception of the Base Station ACK. SELECT Preamble Spreading Code Yes END TRANSMIT Random Access Burst SELECT Message Spreading Code November 18 V2.0Raul Bruzzone
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Handover Procedures November 18 Raul Bruzzone
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Soft Handover (I) During Soft Handover, two or more Base Stations are used to simultaneously communicate with the same Mobile Station. These Base Stations form the Active Set. All Active Set Base Stations use the same RF Carrier Frequency. Each Active Set Base Station maintains its own Scrambling Code. November 18 Raul Bruzzone
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Soft Handover (II): Active Set Update
PROCEDURE MONITOR other Base Stations in current Carrier REPORT to Network those BS above threshold UPDATE Active Set MEASURE corresponding Signal Strengths RECEIVE Update Messages from the Network This is a periodic procedure performed at the Mobile Station during Active Mode (the mode during on-going communication). November 18 Raul Bruzzone
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Softer Handover It is the special case of Soft Handover in which Active Set Base Stations are part of the same physical site. Softer Handover allows more efficient combining implementations than Soft Handover (e.g. to use Maximal Ratio Combining instead of Selection Combining). November 18 V2.0Raul Bruzzone
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Inter-frequency Handover (I)
In Inter-frequency Handover, the RF carrier frequency changes. It is used in the following situations: Handover between cells using different RF carrier frequencies. Handover between overlapping cells. Handover between different Operators and/or Systems (e.g. UMTS/GSM). November 18 Raul Bruzzone
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Inter-frequency Handover (II) Hierarchical Cell Structures
Hierarchical Cell Structures (HCS) are set of cells geographically co-located, but using different RF carriers. Inter-frequency Handover is required in HCS. November 18 European Commission
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Inter-frequency Handover (III) Mobile Implementation
Slotted Mode Two strategies are suggested: Slotted Mode (see right) Dual Receivers. November 18 ETSI
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Physical Layer Description (FDD) Summary (I)
UMTS-FDD is a Code Division Multiple Access (CDMA) system. The Spreading Factor associated to each channel may be independently selected. Cells are characterized by a specific spreading code (Scrambling Code). Communication Sessions are also characterized by a specific spreading code (Channelization Code). Pilot Symbols are used to allow coherent detection of QPSK signals and spreading codes. November 18 Raul Bruzzone
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Physical Layer Description (FDD) Summary (II)
In the downlink, two synchronization channels (primary and secondary) are regularly transmitted to allow attachment of the mobile stations. Moreover, a broadcast channel (BCCCH) is regularly transmitted in order to provide to the mobile stations, information about specific parameters from the Cell. In order to avoid the Near-Far Effect, UMTS incorporates 3 Power Control mechanisms: Open, Outer and Closed Loops. Soft Handover is used when a mobile station migrates between Cells operating at the same carrier frequency. November 18 Raul Bruzzone
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Time Division Duplex (TDD) Mode
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TDD Frame Structure 16 Time Slots (TS) 1 Time Slot = 2560 chips
frequency 10 ms 4.096 Mchip/s 625 µs time 16 Time Slots (TS) 1 Time Slot = 2560 chips Each TS may be used in Uplink or Downlink At least one TS must be used in Uplink At least one TS must be used in Downlink November 18 Raul Bruzzone
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Single Switching Point Frames
10 ms Symmetric DL/UL Allocation 10 ms Asymmetric DL/UL Allocation November 18 3GPP
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Multiple Switching Point Frames
10 ms Symmetric DL/UL Allocation 10 ms Asymmetric DL/UL Allocation November 18 3GPP
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Use of CDMA in the TDD Mode (TD-CDMA Concept)
1 Time Frame = 10 ms code 8 . . . . code 1 1 TS = 625 µs TDD mode traffic capacity is increased by means of superimposing several signals in the same Time Slot. Each Signal differs from the other in the use of a separate Spreading Code. In general, up to 8 signals may be code-multiplexed. November 18 3GPP
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Transport Channels and Physical Channels
Concepts of Transport Channels and Physical Channels Layer 2 Layer 2 Transport Channel Transport Channel Layer 1 Processing Layer 1 Processing Layer 1 This slide illustrates the concepts of Transport and Physical channels, for the case of an uplink communication. Physical Channel User Equipment UTRAN November 18 Raul Bruzzone
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TDD Transport Channels
Common Dedicated Broadcast Channel Dedicated Channel (DCH) (BCH) Paging Channel ODMA Dedicated Channel (ODCH) (PCH) Forward Access Channel (FACH) Synchronization Channel (SCH) This chart shows the classification of UTRA uplink physical channels. Downlink Only Random Access Channel Uplink Only (RACH) Uplink / Downlink ODMA Random Access Channel (ORACH) November 18 Raul Bruzzone
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TDD Physical Channels Physical Channels Common Dedicated
Common Control Physical Channel Dedicated Physical Channels (DPCH) (CCPCH) Physical Synchronization Channel (PSCH) Physical Random Access Channel (PRACH) This chart shows the classification of UTRA uplink physical channels. Downlink Only Uplink Only Uplink / Downlink November 18 Raul Bruzzone
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TDD Burst Types Burst Type 1 Burst Type 2 November 18 Raul Bruzzone
This mode has two possible type of bursts. Each burst is specially optimized for different applications. November 18 Raul Bruzzone
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Dedicated Physical Channels Burst Types Application
Burst Type 1 has a longer Midamble. Therefore it allows a more accurate multi-user detection, as is required in the Uplink. Burst Type 2 has a shorter Midamble, and therefore, higher User Data throughput. It is more suitable for the Downlink, which will require more capacity in, e.g. Wireless Internet applications. November 18 Raul Bruzzone
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Common Control Physical Channels
Used to transport the BCH, PCH and FACH. Burst type is the same as for the Dedicated Physical Channels (DPCHs) November 18 Raul Bruzzone
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Physical Random Access Channels
These channels support the bursts send by UEs in order to signal their presence to the Base Station of the cell where they intend to camp on. As bursts are randomly sent, a certain risk of collision in the same Time Slot exists. As each access burst has its own Spreading Code (8 different options), the risk of collision is significantly reduced. November 18 Raul Bruzzone
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Physical Random Access Channels Access Bursts
Two types of Random Access Bursts are specified. Each Burst uses only 1/2 Time Slot. The UE may send both bursts in a single Time Slot, thereby increasing the probability of reaching the Base Station without collision. Extended GP Data Midamble GP 625 µs 312.5 µs Access Burst 1 Access Burst 2 November 18 3GPP
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Physical Synchronization Channel (PSCH)
It has a similar structure as in the FDD mode. Two code sequences are periodically broadcasted: Primary Synchronization Code (Cp) Secondary Synchronization Code (Cs) In each Frame, two Time Slots are allocated for the Primary Synchronization Channel: TS0 and TS7. November 18 3GPP
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Physical Synchronization Channel (PSCH) Internal Burst Structure
November 18 3GPP
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Mapping of Transport Channels on Physical Channels
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Mapping of BCH, PCH and FACH on CCPCHs
Layer 2 Layer 2 FACH PCH BCH BCH PCH FACH Radio Interface Layer 1 Processing CCPCH Layer 1 Processing In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs. This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels. Layer 1 Processing CCPCH Layer 1 Processing Layer 1 Processing CCPCH Layer 1 Processing User Equipment UTRAN November 18 Raul Bruzzone
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Mapping of DCHs and ODCHs on DPCHs
Layer 2 Layer 2 DCH DCH Radio Interface DCH DCH ODCH PCH ODCH ODCH Layer 1 Processing DPCH Layer 1 Processing DPCH In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs. This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels. Layer 1 Processing DPCH Layer 1 Processing DPCH User Equipment UTRAN November 18 Raul Bruzzone
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Mapping of RACH on PRACH
Layer 2 Layer 2 RACH RACH Radio Interface Layer 1 Processing PRACH Layer 1 Processing In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs. This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels. User Equipment UTRAN November 18 Raul Bruzzone
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Mapping of ORACH on PRACH
Layer 2 Layer 2 ORACH ORACH Radio Interface Layer 1 Processing PRACH Layer 1 Processing In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs. This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels. User Equipment Relay Station November 18 Raul Bruzzone
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Mapping of SCH on PSCH User Equipment UTRAN Layer 2 Layer 2 SCH SCH
Radio Interface Layer 1 Processing PSCH Layer 1 Processing In this slide, each BCH, PCH and FACH are mapped on independent CCPCHs. This may be only required if the PCH or FACH traffics in the particular cell are very high. In other cases, a single CCPCH may support several Transport Channels. User Equipment UTRAN November 18 Raul Bruzzone
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Physical Layer Description (TDD) Summary
In the TDD mode, the same carrier frequency is used in the uplink and downlink. This mode allows asymmetric communication by allocating different number of Time Slots in the uplink and downlink. Each Time Frame contains 16 Time Slots. Each Time Slot may allocate 8 users, that may be distinguished by different Spreading Codes. November 18 Raul Bruzzone
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Data Communication Protocols
coming next ... UTRA Data Communication Protocols Description November 18 Raul Bruzzone
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