HSUPA Performance in Indoor Locations

Pedro Miguel Cardoso Ferreira

Abstract – This paper presents results of HSUPA

performance tests in a live network and in various

indoor environments. Tests were performed in

locations with different indoor coverage solutions:

indoor locations covered by outdoor sites,

dedicated indoor site, optical repeater and RF

repeater.

Keywords – HSUPA, indoor, real live

performance, throughput.

I. Introduction

This paper collects the results of several tests were

data transfers were performed using UMTS

HSUPA feature. HSUPA also known as Enhanced

Uplink was defined by 3GPP [1] in Release 6 with

the goal of improving UMTS uplink data transfers

in a somewhat similar way HSDPA did for

downlink. The main innovations which came with

HSUPA were: fast Node B based scheduling, fast

physical layer HARQ and optional 2ms TTI. These

features together with the possibility of using SF2

it will allow in the near future peak data rates of

5.76MBps[2]. The tests were performed in four

different indoor locations, each one with different

characteristics and different solutions for indoor

coverage. In the first test scenario the indoor

coverage was provided by the outdoor network

whereas in the rest a dedicated indoor system was

present. The second test scenario was in a location

with a dedicated indoor site, the third in an indoor

location with an optical repeater and finally the

fourth test scenario was located in a building with

a RF repeater. From those tests a number of

different metrics were collected to evaluate the

performance of the data transfer, namely:

Throughput [kbps], Ec [dBm], Ec/I0 [dB] and

Noise Rise [dB].

II. Test Description

In each test scenario three test points were chosen

with different radio characteristics. For each of the

test points, consecutive uploads of a 5MB file

were performed with intervals of 10s in between

each upload. These tests try to emulate usual tasks

which use HSUPA, as photo transfers or work files

uploads, etc. Uploads were performed from a

laptop equipped with a HSUPA compatible UE to

a ftp server directly connected to the GGSN

therefore avoiding throughput fluctuations not due

to the mobile network. The test setup is shown in

Figure 1.

Figure 1: Test Setup

III. Test scenarios

In the first test scenario the indoor coverage was

provided by an outdoor site, which is by far the

most common situation in indoor scenarios. In this

scenario three test points were chosen. P1 next to

the window with potentially the best received

signal strength but also the highest interference

form other sites. P2 in a standard indoor location

with some walls in the direct path to the serving

site. And finally P3, in a deep indoor location with

the worst radio conditions.

Figure 2: Outdoor site

The second test scenario was located in a building

with a dedicated site, which is a solution normally

used in buildings where a large number of users

are expected either/or special service demands are

forecasted. The coverage was in this case

guaranteed through a distributed antenna system,

which is partially shown in Figure 3for the serving

antenna.

Figure 3: Dedicated site diagram

The serving antenna was located in a room of the

building where three test points were chosen: the

first one by the window, a second one in the direct

vicinity of the serving antenna and a third one in a

standard indoor position; which can be seen in

Figure 4. Test points with the same characteristics

were chosen in the other test scenarios with

dedicated systems.

Figure 4: Dedicated site test layout

For the third test scenario a building in which

dedicated coverage is provided by an optical

repeater was chosen. The building layout with the

location of the serving antenna and the three test

points is shown in Figure 5.

Figure 5: Optical repeater test layout

Optical repeaters are used in similar locations as

dedicated sites. Optical repeaters allow however

larger distances between the base station and

antennas, because the larger part of this distance is

connected via fibre optics which presents lower

losses than coaxial cable. Moreover the signal is

regenerated before being converted back to RF. An

excerpt of the block diagram containing the

serving antenna is shown in Figure 6.

Figure 6: Optical repeater diagram

Finally the last test scenario was located in a

building with coverage guaranteed by a RF

Repeater connected to a distributed antenna

system. A floor plan of the test scenario where

serving antenna and test points are marked can be

seen in Figure 7.

Figure 7: RF repeater test layout

RF repeaters receive signal from an outdoor site

via a donor antenna and, in normal indoor cases,

feed a distributed antenna system. The repeater

itself only filters and amplifies the incoming signal

and noise. RF repeater deployment is the cheapest

way to boost indoor capacity, so they are used in

locations whenever no capacity upgrade is

foreseen and a limited area is to cover, due to its

limited output power. A diagram showing the

serving antenna integrated in the RF repeater

system can be seen in Figure 8.

Figure 8: RF repeater diagram

IV. Results

All tests were performed according to the

methodology already presented, using a power

class 3 UE. Regarding HSUPA capability a

category 3 UE was used, meaning a maximum of 2

SF4 and a 10ms TTI was supported, therefore the

maximum theoretical physical throughput was

limited to 1.45Mbps [2]. All the metrics were

collected with the tool TEMSTM

Investigation [3].

In the test scenario where the indoor coverage was

provided by an outdoor site one can see in Figure 9

that, as expected, the average received signal

strength decreases as we move indoor.

Figure 9: RSCP outdoor site

Nevertheless this reduction as little impact on the

signal quality as can be seen in Figure 10, only test

point 3 shows a small degradation.

Figure 10: Ec/I0 outdoor site

The UE transmitted power increase is, as expected,

proportional to the received signal strength

decrease, as can be seen in Figure 11.

Figure 11: UETxPwr outdoor site

Regarding the noise rise due to the tests, Figure 12

shows that its value is small. It varies between

0.3dB and 0.8dB in test points 2 and 3

respectively. However the difference towards the

average RTWP is smaller or even inexistent in P2.

This RTWP_AVG values was calculated based on

hours adjacent to the ones the tests were performed

when mostly R99 services were carried by the

network.

Figure 12: RTWP [dBm] outdoor site

Finally in Figure 13 one can observe that despite

the previous differences in some collected

statistics the uplink application throughput was

practically constant in all test points.

Figure 13: UL Throughput outdoor site

For the dedicated site scenario the received signal

strength was as foreseen, stronger on the antenna

test point and almost equal in the other two points.

Figure 14 presents the collected values.

Figure 14: RSCP dedicated site

Figure 15: Ec/I0 dedicated site

In Figure 15, one can see that despite the received

signal being almost equal in P1 and P3 due to the

fact that the window location is a bit more exposed

to outside interference the received signal quality

is slightly worse in P1. This can explain as well

the difference seen in Figure 16 for the UE

transmitted power, where the average value

collected in P1 is higher than P3.

Figure 16: UETxPwr dedicated site

Once again, as seen in Figure 17, the impact on

noise rise of HSUPA is reduced and in this case

similar in the three test points.

Figure 17: RTWP [dBm] dedicated site

There almost no difference in the throughput

between the three test points in the dedicated site

scenario, as can be observed in Figure 18.

Figure 18: UL Throughput dedicated site

In the optical repeater scenario the RSCP for the

three test points follows a more natural pattern

with the highest value close to the antenna,

followed by the window location and the standard

indoor location, as can be seen in Figure 19.

Figure 19: RSCP optical repeater

Regarding the signal quality, Figure 20 shows that

it is good in all test points with slightly better

values in the test point by the antenna, as should

be expected.

Figure 20: Ec/I0 optical repeater

The UE transmitted power follows closely the

received signal strength, as the obtained results in

Figure 21 demonstrates.

Figure 21: UETxPwr optical repeater

Figure 22: RTWP [dBm] optical repeater

Figure 22 shows that noise rise is in this scenario

much higher than in previous ones, reaching

values around 3dB. Nevertheless, differences

between the three test points remain small.

Figure 23: UL Throughput optical repeater

Albeit the differences in noise rise, one can see in

Figure 23 that the uplink application throughput

values remain high. In this case P3 shows a small

but noticeable worse value than the other points.

The RSCP in the RF repeater scenario is shown in

Figure 24. The values follow what should be

expected according to the test locations.

Figure 24: RSCP RF repeater

This is not the case for the Ec/I0, seen in Figure

25, where the window location strangely presents

the best values. A possible explanation is a

coherent combination of the signal from the indoor

antenna and the repeated outdoor site at this point.

Figure 25: Ec/I0 RF repeater

Again there is in this case a match between the

RSCP and the UE transmitted power, which can be

observed in Figure 26.

Figure 26: UETxPwr RF repeater

Regarding the noise rise, Figure 27 shows that also

in this scenario the tests caused a bigger impact

than in the solutions with no repeaters. Although

in this case the value is about 1dB which is

significantly less than in the optical repeater

scenario. Once again the difference between test

points is barely visible.

Figure 27: RTWP [dBm] RF repeater

Once again Figure 28 shows very good and even

results in terms of throughput in all test points.

Figure 28: UL Throughput RF repeater

In Figure 29, one can observe the average radio

conditions and standard deviations values in which

the tests were performed, for the four scenarios.

The presented values sum up the results from the

three test points in each scenario. As can be seen

the scenarios with indoor dedicated coverage

systems present, as expect, higher received signal

strength than the case where indoor is covered by

an outdoor site. Conversely, the signal quality

shows higher values for the outdoor scenario than

the dedicated systems scenarios.

Figure 29: Radio conditions Ec vs Ec/I0

The average UE transmitted power and standard

deviation values are shown in Figure 30. The

achieved results follow closely the ones from the

received signal strength, with the exception of the

optical repeater. This scenario despite the fact of

presenting the highest RSCP shows a higher UE

transmitted power value. This should be caused by

the attenuator used to reduce the downlink signal

due to the input power limitations of the optical

system, which also attenuates the uplink signal.

Figure 30: UE transmitted power

Rise over thermal average values for the four test

scenarios are presented in Figure 31, showing a

significant difference between the solutions with

and without repeaters. The dedicated site and

outdoor site scenarios presented small noise rise

values during the tests, therefore is expectable that

a large number of users might use HSUPA

simultaneously in the cell. The tests impact in the

noise rise is much more visible in the repeater

scenarios, especially in the optical repeater. This

behaviour might put a more strict limitation on the

number of HSUPA users allowed in these cases.

Figure 31: Rise over thermal

Despite the differences in the radio conditions on

the several scenarios the achieved uplink

throughput values are quite good for all of them, as

seen in Figure 32. This results are also possible

because the UE is capable of compensate the worst

radio conditions with extra power. Despite the

values being all good there are slight differences

that are inversely proportional to the noise rise

values.

Figure 32: Uplink throughput

V. Conclusions

From the results collected in the conducted tests

one can conclude that HSUPA is a major

improvement in the uplink data transfer

performance. These results were nevertheless

achieved in good radio conditions and low load.

Moreover, the tests were performed with HSUPA

limited to 2 SF4 and 10ms. There is also no

significant difference in uplink throughput

between the different indoor coverage solutions.

However indoor coverage solutions based on

repeaters present a higher noise rise due to

HSUPA which can be an important limitation to

the cell capacity.

REFERENCES

[1] http://www.3gpp.org/specifications

[2] Holma,H. and Toskala,A., HSDPA/HSUPA

For UMTS, High Speed Radio Access forMobile

Communications, John Wiley & Sons, UK, 2006.

[3]http://www.ericsson.com/solutions/tems/index.s

html