5. wcdma hsupa principle

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WCDMA HSUPA

Principles


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


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


Contents

Introduction of HSUPA HSUPA Concepts Physical Layer Channel and Processing MAC Protocols and Procedure


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


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


HSDPA, HSUPA and DCH comparison table

Presenter

Presentation Notes

The HSUPA feature of the 3GPP WCDMA systemis in fact a new uplink transport channel – E-DCH – that brought some of the same features to the uplink as the HSDPA with its new transport channel – high-speed downlink shared channel (HS-DSCH) – provided for the downlink. The E-DCH transport channel supports fast Node B based scheduling, fast physical layer HARQ with incremental redundancy and, optionally, a shorter 2-ms transmission time interval (TTI). Though – unlike HSDPA – HSUPA is not a shared channel, but a dedicated one, by structure the E-DCH is more like the DCH of Release 99 but with fast scheduling and HARQ than an uplink HSDPA: that is, each UE has its own dedicated E-DCH data path to the Node B that is continuous and independent fromthe DCHs and E-DCHs of other UEs.


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


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


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


Contents



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)


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


DPDCH and E-DPDCH comparison table


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


HSUPA – scheduling-related information exchanged over the air

Presenter

Presentation Notes

HSUPA scheduling is facilitated using three physical channels, E-AGCH and E-RGCH in the downlink and a happy bit carrying E-DPCCH in the uplink. In addition to this the E-DPDCH delivers an SI message in the MAC-e header for additional details for the Node B scheduler. SI can be used in the Node B scheduler in addition to the happy bit received on the E-DPCCH and the observed power allocation usage a given UE is using. It should be noted, though, that SI is only available when it is actually triggered for transmission either as a result of increased data levels in the buffer or as a result of timer elapse, and when the scheduling HSUPA cell receives the transmitted packet correctly.


HSUPA scheduling in soft handover


Contents



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


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


Transport channel processing details

Presenter

Presentation Notes

CRC attachment for the E-DCH always attaches a 24-bit CRC to the transport block received fromthe MAC layer. In comparison, the CRC length for the DCH is configurable and can be 0, 8, 12, 16, or 24 bits. Code block segmentation for the E-DCH splits its input into equal size code blocks so that the length of the block does not exceed 5114 bits. For theDCHthe same block first concatenates the transport block set to a single block of data before splitting. Also the size of the maximum code block with the DCH depends on the coding in use (5114 for turbo-coding and 504 for convolutional coding). Channel coding for the E-DCH is always turbo-coding with a code rate of 1/3. DCH channel coding may be either convolutional coding with code rates 1/2 or 1/3 or turbocoding with a code rate of 1/3. Physical layer HARQ funtionality/rate matching for the E-DCH matches the channel codes output bits to the available physical channel bits and produces the different redundancy versions needed for incremental redundancy HARQ. Physical channel segmentation for the E-DCH distributes the channel bits among the multiple E-DPDCHs if more than one E-DPDCH is needed. The functionality is also the same in the corresponding block in the DCH processing chain. Interleaving and physical channel mapping for the E-DCH, as well as for the DCH, interleaves the bits in the radio frame and maps the bits to be transmitted to their final positions in the physical channel.


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


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.


E-AGCH coding chain


E-AGCH frame structure


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)


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


Contents



HSUPA MAC-e PDU structure

Presenter

Presentation Notes

Total E-DCH buffer status (TEBS, 5 bits) reveals the total amount of data in the UE’s transmission buffer. This information can be used by the scheduler for deciding the data rate the UE could actually use. 2. Highest priority logical channel ID (HLID, 4 bits) indicates the highest priority logical channel that has data in the UE’s transmission buffer. 3. Highest priority logical channel buffer status (HLBS, 4 bits) reveals the amount of data in the buffer for the logical channel indicated by the HLID. The HLID and HLBS can be used by the Node B scheduler for deciding which UEs should be served first or served with higher data rates. 4. UPH (5 bits) indicates the Node B of the power ratio of maximum allowed UE transmit power to DPCCH pilot bit transmit power. In essence, the ratio tells the Node B scheduler how much relative power the UE can use for its data transmission. This information can be used by the Node B not to schedule any given UE a higher power allocation than it is actually capable of transmitting due to transmit power limitation.


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


HSUPA HARQ process timing with a 10-ms TTI


HSUPA HARQ process timing with a 2-ms TTI


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


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


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


Thank’s

5. wcdma hsupa principle

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