5. wcdma hsupa principle
TRANSCRIPT
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WCDMA HSUPA
Principles
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Foreword
HSUPA: High Speed Uplink Packet Access HSUPA, as one of important feature from Huawei RAN6, has been taken as an important
enhancement to improve the network performance
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Objectives
Upon completion of this course, you will be able to: 1.Outline the protocol architecture of HSUPA 2.Know the key technologies of HSUPA
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Contents
Introduction of HSUPA HSUPA Concepts Physical Layer Channel and Processing MAC Protocols and Procedure
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High Speed Uplink Packet Access
Driver force for HSUPA - Data Rate – demand for higher peak data rates in uplink - Qos – lower latency - Capacity – better uplink throughput - Coverage – better uplink coverage for higher data rate
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WCDMA Evolution
Mobile Network Upllink Peak Data Rate Downlink Peak Data Rate
GSM 9.6kbps 9.6kbps GPRS 20kbps 40kbps EDGE 60kbps 120kbps
WCDMA Release 99 384kbps 384kbps
HSDPA Release 5 384kbps 10Mbps
HSUPA Release 6 1.4Mbps/5.76Mbps 10Mbps
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HSDPA, HSUPA and DCH comparison table
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Release 99 Uplink Packet Data
DCH (Dedicated Channel) - Variable spreading factor - Closed loop power control - Marco diversity (soft handover) RACH
- Common spreading code - Fixed spreading factor - No closed loop power control - No soft handover
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Release 99 Uplink Limitation
Large scheduling delay - Radio resource is controlled from RNC - Uplink DCCC (Dynamic channel configuration control) Large latency
- Transmission time interval duration of 10/20/40/80ms - RNC based retransmission in case of errors (RLC layer) Limited uplink data rate
- Deployed peak data rate is 384kbps with limited subscriber number
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Improved Characters by HSUPA
Higher peak data rate in uplink Reduced latency
- Faster retransmission to improve throughput Fast scheduling
- Optimize the resource allocation to maximize the total throughput Quality of service support
- Improve QoS control and resource utilization
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Contents
Introduction of HSUPA HSUPA Concepts Physical Layer Channel and Processing MAC Protocols and Procedure
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HSUPA VS HSDPA
HSDPA HSUPA
New high-speed shared channel Dedicated channel with enhanced
capabilities
HARQ with fast retransmission at layer 1
Rate/modulation adaptation Single serving cell Fast power control Soft handover
Fast NodeB scheduler
Shared NodeB power and code
Fast NodeB scheduler
Rise-over-Thermal (ROT)
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Rise-over-Thermal Noise
In order to decode received data correctly, the uplink interference chall be controlled Rise-over-Thermal is measure of the uplink load
NodeB monitor uplink interference and tells UE how much power can be used to transmit
uplink data
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DPDCH and E-DPDCH comparison table
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HSUPA Channel Operation
The UE sends a transmission request to the NodeB for getting resources The NodeB responds to the UE with a grant assignment, allocation uplink band to the UE The UE uses the grant to select the appropriate transport format for the Data transmission to the
NodeB The NodeB attempts to decode the received data and send ACK/NACK to the UE. In case of
NACK, data may be retransmitted
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HSUPA – scheduling-related information exchanged over the air
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HSUPA scheduling in soft handover
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Contents
Introduction of HSUPA HSUPA Concepts Physical Layer Channel and Processing MAC Protocols and Procedure
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New Channel for HSUPA
Uplink Transport Channel E-DCH: Carries high speed uplink data Uplink Physical Channels E-DPDCH: Carries E-DCH E-DPCCH: Carries control signal for E-DPDCH Downlink Physical Channels E-HICH : Carries HARQ ACK/NACK indicator for E-DCH E-RGCH : Carries relative grant determined by the scheduler E-AGCH : Carries absolute grant determined by the scheduler
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New Channel is HSUPA Operation
The UE sends a request for resources. The request includes status of its data buffers and is sent on E-DPDCH Based on the request from the UE, the Node B allocates a resource grant to the UE. The grant is
sent on the E-AGCH channel This grant can be modified by the Node B every TTI using the E-RGCH channel The UE transmits data on E-DPDCH. Control information needed to decode the data is sent on E-
DPCCH. The NodeB decodes the received packet and informs the UE whether it could decode the data
successfully or not on the E-HICH channel
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Transport channel processing details
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E-AGCH
E-AGCH is common downlink channel Fixed data rate : 30kbps QPSK modulation Spreading factor : 256 E-AGCH carries abdolute grant for E-DCH for all Ues in the cell Transmission on E-AGCH can be 2ms or 10ms 2ms if E-DCH TTI is 2ms 10ms if E-DCH TTI is 10ms UE listens to the E-AGCH from the serving cell only
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E-AGCH coding chain
Absolute grant value is a 5-bit integer number ranging from 0 to 31 that has a specific mapping [3] to the E-DPDCH/DPCCH power ratio the UE may use. Absolute grant scope can be used to activate/de-activate a particular HARQ process (identified by
the E-AGCH timing) or all HARQ processes. The absolute grant scope can only be used with a 2-ms E-DCH TTI. Primary/Secondary UE-id or primary/secondary E-DCH radio network temporary identity (E-RNTI)
is used to mask the CRC of the E-AGCH. Each UE may have up to two UE-ids which it checks fromeach E-AGCH and if it detects one or the other as matching the transmission it knows that the E-AGCHtransmission was destined for it.
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E-AGCH coding chain
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E-AGCH frame structure
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E-HICH
E-HICH is a dedicated downlink channel that carries HARQ ACK/NACK QPSK modulation Spreading factor is 128 and the channelization code for E-HICH is same with E-RGCH Transmitted from all cells in the E-DCH active set ACK/NACK is indicated using a binary indicator ACK is +1 NACK from cell is serving E-DCH radio link set is -1 NACK from cells not in serving E-DCH radio link set is 0 (DTX)
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Channel Configuration
E-DCH can be established in combilation with he following downlink configurations: - Downlink DCH only - HS-DSCH only - Both DCH and HS-DSCH The following uplink configuration are possible:
- Uplink DCH only - E-DCH only - Both uplink DCH and E-DCH Downlink and uplink configurations can be combined independently
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Contents
Introduction of HSUPA HSUPA Concepts Physical Layer Channel and Processing MAC Protocols and Procedure
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HSUPA MAC-e PDU structure
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Hybrid ARQ (HARQ) Operation
N-channel Stop-and Wait (SAW) protocol, with 4 processes for 10 ms TTI and 8 processes for 2 ms TTI for continuous transmission Synchronous retransmission, fixed timing relation means no need for process ID Separate HARQ feedback is provided per radio link
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HSUPA HARQ process timing with a 10-ms TTI
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HSUPA HARQ process timing with a 2-ms TTI
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Scheduled Transmission
In the downlink, the NodeB allocates scheduling grants to UE to tell UE the maximum amount of uplink resource it can use. - Scheduling grants indicates the maximum allowed E-DPDCH/DPCCH power ratio (T/P ratio) - Scheduling grants are used by the UE to compute largest permitted transport block (E-TFC selection) - There are two types of scheduling grants:
- The absolute grants provide an absolute limitation of the maximum amount of UL resources the UE may use
- The relative grants increase or decrease the resource limitation compared to the previously used value
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Absolute Grant
Absolute grants are carried by the E-AGCH chanel of the serving E-DCH cell The following information is carried by E-AGCH
- UE ID : E-RNTI specific CRC for addressing - Grant : An index to one of 31 value for traffic-to-pilot- ratio - HARQ process control : Deactivate/Active HARQ process
- Absolute grant with value 0 is used to deactivate HARQ process - Scope: Indicates the grant affects one or all HARQ processes
- For 10ms E-DCH TTI, the scope is always set to all processes
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Rules for Updating Serving Grant
Serving E-RGCH commands are ignored for one HARQ RTT if E-AGCH is received If a down command is received from the non-serving cell, the UE ensures forone HARQ RRT that
serving grant is not higher than the grant considered after reception of the non-serving E-RGCH
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Thank’s