Transcript The Impact of Indoor Traffic on the Performance of WCDMA High Speed Downlink Packet Access Within Macro Cells

The Impact of Indoor Traffic on the
Performance of WCDMA HSDPA Within Macro
Cells
Author: Mathias Nyman
Supervisor: Prof. Sven-Gustav Häggman
Instructor: Kimmo Hiltunen, Lic.Sc.(Tech.)
Contents
1. Background, Research Objectives and Methods
2. Basics of HSDPA
3. Simulated Environment and HSDPA Parameters
4. Simulations and Results
5. Conclusions
© LMF Ericsson 2006
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Background and Objectives

HSDPA starting to appear in 3G networks

Coverage is a crucial factor for success – macro cell coverage in
the first place

Fraction of indoor packet data users is estimated to be 70% in the
future  building penetration loss

The aim of this thesis is to study how the network performance is
affected by the indoor traffic

Research methods: Litterature study (HSDPA and propagation
models) and computer simulations
© LMF Ericsson 2006
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Contents
1. Background, Research Objectives and Methods
2. Basics of HSDPA
3. Simulated Environment and HSDPA Parameters
4. Simulations and Results
5. Conclusions
© LMF Ericsson 2006
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Basics of HSDPA

Shared Channel Transmission
–
–
New HS-DSCH Transport Channel
Dynamically shared power and code
resource
SF=1
SF=2
SF=4
Channelization codes allocated
for HS-DSCH transmission
8 codes (example)
SF=8
SF=16
TTI
Shared
channelization
codes
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Basics of HSDPA

Shared Channel Transmission
–
–
New HS-DSCH Transport Channel
Dynamically shared power and code
resource
Total available cell power
HS-DSCH
Dedicated channels (power controlled)
Common channels (not power controlled)
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Basics of HSDPA

Shared Channel Transmission
–
–

New HS-DSCH Transport Channel
Dynamically shared code resource
Adaptive Modulation and Coding
–
–
© LMF Ericsson 2006
Data rate adapted to radio
conditions
2 ms time basis
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Basics of HSDPA

Shared Channel Transmission
–
–

Adaptive Modulation and Coding
–
–

Data rate adapted to radio
conditions
2 ms time basis
Fast Scheduler
–
–

New HS-DSCH Transport Channel
Dynamically shared code resource
2 ms time basis
Round Robin, Proportional Fair or Max-C/I
Hybrid ARQ
–
© LMF Ericsson 2006
Soft combination of multiple
attempts
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Contents
1. Background, Research Objectives and Methods
2. Basics of HSDPA
3. Simulated Environment and HSDPA Parameters
4. Simulations and Results
5. Conclusions
© LMF Ericsson 2006
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Simulated Environment

Seven 3-sector sites, wraparound

Both outdoor and indoor users

COST-WI propagation model

Shadow fading std: 10 dB

Multipath channel: 3GPP Typical
Urban

Position dependent building
penetration loss

Only HSDPA traffic
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HSDPA Parameters

Modulation: QPSK / 16QAM

HS-PDSCH codes: 10

Scheduling Policy: Proportional Fair

GRAKE Receiver

Traffic type: Interactive, 200kB data packets
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Contents
1. Background, Research Objectives and Methods
2. Basics of HSDPA
3. Simulated Environment and HSDPA Parameters
4. Simulations and Results
5. Conclusions
© LMF Ericsson 2006
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Impact of Indoor Users

Building penetration causes
the A-DCH power to be
increased

HS-power is also
attenuatedlower CIR

Increased transmission delay
Total available cell power
HS-DSCH
Dedicated channels (power controlled)
Common channels (not power controlled)
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Power distribution (non-HS
channels)

Very little power reserved for
the non-HS channels when
most of the users are located
outdoors

As the fraction of indoor users
increase, more power is used
by the non-HS channels.
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Active A-DCHs per cell

As the fraction of indoor users
increase, there will be more
simultaneous active links per
cell

Note that the number of
available A-DCHs is 84 in
these simulations
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Network performance for different
fractions of indoor users

The network performance is
clearly decreasing as the
fraction of indoor users
increase.
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Floor height gain

The performance is worse for
the ground floor users
(dashed lines) due to the floor
height gain.

Ground floor users are
exposed to ~14.5 dB more
path loss than the top floor
(6th floor) users.
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Indoor margin

The system performance is
presented for different path loss
values when all users are located
outdoors

An additional path loss of 19 dB
corresponds to the performance
of the case with an indoor user
fraction of 75%.

Appropriate ”indoor margins” can
be taken into account if the
amount of indoor users can be
estimated.
© LMF Ericsson 2006
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Contents
1. Background, Research Objectives and Methods
2. Basics of HSDPA
3. Simulated Environment and HSDPA Parameters
4. Simulations and Results
5. Conclusions
© LMF Ericsson 2006
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Conclusions

Larger fraction of indoor users  decreased network performance

Estimation of the indoor usage will help when designing the
network (indoor margin).

A cost-effective macro cellular solution will be suitable in the initial
phase, dedicated indoor systems etc. will be required later

Further study: Real network measurements including other traffic
than HSDPA, follow-up on HSDPA usage (share of total traffic,
amount of indoor usage, etc.)
© LMF Ericsson 2006
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