OWO145020 WRAN13 DC-HSDPA+MIMO Feature Description ISSUE 1.01

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Confidential Information of Huawei. No Spreading Without Permission

WRAN13.0 DC-HSDPA+MIMO Feature Description

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DC-HSDPA+MIMO is specified in 3GPP Release 9.

DC-HSDPA+MIMO evolves from the HSDPA feature specified in 3GPP Release 5.

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In RAN11.0, 64QAM and MIMO improve user experience greatly. They especially increase

the user rate under advantageous channel conditions. Their advantages for cell-edge users,

however, are insignificant.

To extend the service life of the HSPA+ technology, 3GPP has tried many ways to further

improve the system performance and user throughput since Release 6. 3GPP introduces

dual-cell HSDPA (DC-HSDPA) in Release 8. This feature improves the user throughput by

using a wider spectrum. The peak rate per user increases to 42 Mbit/s (with DC-

HSDPA+64QAM).

3GPP specifies DC-HSDPA+MIMO in Release 9. This feature combines DC-HSDPA in Release

8 and MIMO in Release 7. This feature allows NodeB to send HSDPA data to a UE

simultaneously over two adjacent carriers on the same frequency band within the same

coverage area in MIMO mode. The peak rate per user increases to 84 Mbit/s theoretically

(with DC-HSDPA+MIMO+64QAM).

If an operator owns two or more carriers, DC-HSDPA+MIMO can benefit the system and

users greatly and thereby sharpen the competitiveness of the operator.

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Carrier configurations

In DC-HSDPA+MIMO mode, uplink connections exist on only the primary carrier.

Downlink connections exist on both carriers. On the primary carrier, the UE

monitors all downlink physical channels. On the secondary carrier, the UE monitors

only the P-CPICH and HSDPA related physical channels.

Both MIMO carriers must be configured in P/S-CPICH mode.

Bearer services

CS and voice services are carried on the primary carrier.

BE and stream services can be carried on the carrier in DC-HSDPA+MIMO mode as

configured.

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DC-HSDPA+MIMO increases the transmission rate of most users, including the users at low

and medium signal-to-noise ratios (SNRs). In addition, thanks to the scheduling gain, this

feature increases the system capacity, as compared with independent carrier scheduling.

MIMO, however, varies its performance gains with scenarios. MIMO applies especially to

the propagation scenarios at high SNRs or with low delay spreads. In a scenario with good

channel conditions, rich scattering, and low delay spread, MIMO brings a great

performance gain. Therefore, the scenarios to which DC-HSDPA+MIMO applies depend on

the scenarios to which MIMO applies.

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With the DC-HSDPA feature introduced in 3GPP Release 8, the CN delivers up to 42 Mbit/s

rates in the downlink and up to 256 Mbit/s RAB assignment. Therefore, CN does not need

to be adapted to DC-HSDPA+MIMO in RAN13.0.

The UE must be of category 25, 26, 27, or 28.

UEs of categories 25 and 26 support DC-HSDPA+MIMO+16QAM. UEs of categories 27 and

28 support DC-HSDPA+MIMO+64QAM.

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RAN13.0 does not support joint inter-board scheduling.

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A DC-HSDPA+MIMO UE indicates its capability in this information element HS-DSCH

physical layer category extension 3.

A UE of category 28 supports a peak rate of 84.384 Mbit/s at the MAC layer.

2 x 2 x TB_Size/TTI = 2 x 2 x 42192/2 ms = 84.384 Mbit/s

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HARQ combines FEC and ARQ.

With HARQ, the UE saves an erroneously received packet, combines the erroneous data

with the data that the NodeB retransmits, and then decodes the packet.

Located at the physical layer, HARQ reduces the retransmission delay greatly.

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DC-HSDPA+MIMO impacts the following items:

At the MAC layer

MAC-ehs structure

At the physical layer

Channel mapping

Uplink feedback channel

HS-SCCH

HARQ handling

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DC-HSDPA+MIMO supports joint scheduling and improved Layer-2 processing.

Joint scheduling allows transmitting data from the same MAC-d queue over two carrier

cells.

Improved Layer-2 processing allows segmenting an RLC PDU at the MAC layer.

Transmitting the RLC PDU segments over two carrier cells improves the downlink coverage

performance.

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The MAC-ehs entity orders, schedules, and transmits data for UEs with HSDPA, enhanced

HSDPA, and DC-HSDPA+MIMO in a unified manner.

The MAC-ehs entity supports joint inter-carrier scheduling.

A DC-HSDPA+MIMO UE uses two HS-DSCH channels. Each channel is associated with one

HARQ entity.

At least one of the two HS-DSCH channels is configured in MIMO mode. Both channels

can be configured in MIMO+64QAM mode.

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The UE sets up two HS-DSCH connections. Each HS-DSCH connection is configured in

MIMO or MIMO+64QAM mode.

One carrier serves as the primary carrier and the other carrier serves as the secondary

carrier.

The UE sets up dedicated control channels on the primary carrier.

The UE sends CQI feedback in the HS-DPCCH on the primary carrier.

The NodeB transmits data by using two antennas on each carrier.

Both cells with DC-HSDPA+MIMO must be configured in P/S-CPICH mode.

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An HSDPA-MIMO UE in 3GPP Release 7 reports HARQ ACK/NACK and CQI in the HS-

DPCCH.

A DC-HSDPA+MIMO UE also reports the information in a single HS-DPCCH channel.

A new HS-DPCCH frame format is defined for DC-HSDPA. In this format, a frame

carries PCI, two types of CQI, and HARQ ACK/NACK for two carriers during each

TTI.

When the secondary carrier is deactivated, the frame format and feedback

information in the uplink feedback channel for DC-HSDPA+MIMO are identical to

the frame format and feedback information in the uplink feedback channel for

MIMO in 3GPP Release 7.

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UEs of categories 25 to 28 support DC-HSDPA+MIMO.

DC-HSDPA+MIMO reuses the CQI tables for MIMO.

When a DC-HSDPA+MIMO UE is not configured with 64QAM, CQI tables C and D

apply to single-stream transmission and CQI tables H and I apply to dual-stream

transmission.

When a DC-HSDPA+MIMO UE is configured with 64QAM, CQI tables F and G apply

to single-stream transmission and CQI tables J and K apply to dual-stream

transmission.

The specification 25.214 (R9) can be referred for the detailed information about CQI

mapping table C, D, G,H and etc.

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DC-HSDPA+MIMO reuses the HS-SCCH orders for DC-HSDPA to activate and deactivate the

secondary carrier.

The content in HS-SCCH type 1:

CCS: Channelization-code-set information

MS: Modulation scheme information

TBS: Transport-block size information

HAP: Hybrid-ARQ process information

RV: Redundancy and constellation version

ND: New data indicator

* in HS-SCCH order means the bit is reserved.

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If a 100 Mbit/s FE interface is configured for the transmission, the 84 Mbit/s rate may keep

the DSP in DPU* board busy with anti-pressure flow control.

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During RAB setup, a carrier cell is selected according to the following principles:

A DRD candidate set is generated according to the DRD quality conditions.

If the service requires the HSPA+ feature, the cells in the DRD candidate set are

sorted in descending order of the HSPA+ satisfaction. The carrier cell with the

highest HSPA+ satisfaction is preferred. The order of the HSPA+ technical

satisfaction will be discussed in the next slide.

If two carrier cells have the same HSPA+ satisfaction and the service steering switch

is enabled, the carrier cell is selected according to the service steering principles.

If two carrier cells have the same HSPA+ satisfaction and service priority, the carrier

cell is selected according to the load balance principles.

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If downlink Layer-2 enhancement is not considered and DC-HSDPA+MIMO (with

64QAM) has the highest priority, the sorting depends on the maximum rate.

DC-HSDPA (with 64QAM) and MIMO+64QAM are sorted by using a switch.

DC-HSDPA (with 16QAM), MIMO, and 64QAM are sorted by using a switch.

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In the table of the slide, these features are extracted: DC-HSDPA+MIMO+64QAM, DC-

HSDPA+MIMO, and DC-HSDPA+64QAM. They are sorted in this order: DC-

HSDPA+MIMO+64QAM > DC-HSDPA+MIMO > DC-HSDPA+64QAM. (DC-HSDPA

takes precedence over the combinations of MIMO and 64QAM. For example, although

DC-HSDPA+1xMIMO and MIMO+64QAM support the same maximum rate 42 Mbit/s,

DC-HSDPA+MIMO is prior to MIMO+64QAM).

Assume that DC-HSDPA+MIMO+64QAM is available. The combinations of MIMO and

64QAM except DC-HSDPA are sorted according to the maximum rate. For example, the

DC-HSDPA+MIMO+64QAM combinations in the preceding table are sorted in this order:

(1) > (2) > (4) > (3).

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Although a MIMO or DC-HSDPA+MIMO UE may consume an additional physical CE on the

NodeB side, only a licensed CE is consumed on the RNC side.

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From the figure in the slide we can see that

The throughput of DC-HSDPA+MIMO is almost double of MIMO throughput due

to the gain of dual carriers.

Compared with DC-HSDPA, DC-HSDPA+MIMO has 50% gain in cell edge.

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The figure in the slide shows the throughput of full buffer service in single carrier. (For DC-

HSDPA user, the throughput of single carrier means the average throughput per carrier. )

We can see that

DC-HSDPA+MIMO has 8% gain compared with MIMO due to the multi-user

diversity gain.

DC-HSDPA+MIMO has 17% gain compared with DC-HSDPA due to the dual stream

and Tx diversity gain of MIMO.

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From the figure in the slide we can see that

20% of DC-HSDPA users throughput can reach 2Mbps, while 30% of DC-

HSDPA+MIMO users throughput can reach 2Mbps.

10% of DC-HSDPA+MIMO users throughput can reach 3Mbps while no DC-

HSDPA users throughput can reach 3Mbps.


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Burst service is sensitive to time delay. Here we focus on the time delay of burst service.


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From the figure in the slide we can see that DC-HSDPA+MIMO has obvious gain compared

with DC-HSDPA. It is mainly because of MIMO. Whats more, the time delay gain will

increase as the increasing of the UE number.

When there are not many users in the cell, the wireless resource is not limited.

Then the traffic data can be transferred quickly for all the users. The time delay has

no much difference between DC-HSDPA+MIMO and DC-HSDPA.

When there are many users in the cell, the wireless resource is limited. Then the

traffic data can not be transferred quickly for all the users. In this scenario MIMO

can increase the data rate and decrease time delay.


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From the figure in the slide we can see that DC-HSDPA+MIMO has obvious gain compared

with MIMO. It is mainly because of DC-HSDPA. Whats more, the time delay gain will

decrease as the increasing of the UE number.

When there are not many users in the cell, the wireless resource is not limited. The

DC-HSDPA+MIMO user can get wireless resource from both carriers. So DC-

HSDPA+MIMO has much time delay gain compared with MIMO.

When there are many users in the cell, the wireless resource is limited. The DC-

HSDPA+MIMO user can not always get wireless resource from both carriers. So the

time delay between HS-HSDPA+MIMO and MIMO is not so different.


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Ensure that the two DC-HSDPA+MIMO carriers are adjacent. The difference between the

UARFCNDownlink numbers of two adjacent carriers is less than or equal to 25 and greater

than 0. Ensure that the two DC-HSDPA+MIMO carriers have the same Tcell offset.

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Documents

OWO145020 WRAN13 DC-HSDPA+MIMO Feature Description ISSUE 1.01