UIT - Secteur de la normalisation des télécommunications
ITU - Telecommunication Standardization Sector
UIT - Sector de Normalización de las Telecomunicaciones
Study Period 1997-2000
Commission d' études 

Study Group
 16
Comisión de Estudio 

Contributi on tardive 

Delayed Contributi on  D.xxx
Contribuci ón tardía 

Geneva, 7-18 February 2000
Texte disponible seulement en 
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Text available only in
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Texto disponible solamente en 
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Question(s):
SOURCE:
23/16
Motorola ING
CONTRIBUTORS: V. Eyuboglu
D. Forney
D. Kim
S. Mehrabanzad
J. Pilozzi
CONTACT:
Sepehr Mehrabanzad
Phone: +1 (508) 261-5469
Fax: +1 (508) 261-4447
Email: Sepehr.Mehrabanzad@Motorola.com
TITLE:
PCM Upstream Performance Data
_____________________
Abstract
In this contribution we present performance data for PCM upstream modulation using a TAS
network simulator.
1 Introduction
In this contribution we present test results for a prototype full-duplex modem utilizing PCM
modulation in the upstream direction as proposed in companion paper “PCM Upstream
Recommendation V.90 – Issue 2”, D.____ (WP1/16) (see also PCM'99-007).
2 Discussion
This contribution is based on extensive real-world prototype development over the past two years.
These tests show that speeds up to 44 kbit/s upstream can be achieved on good realistic
connections, with graceful degradation in the presence of more severe impairments. Full-duplex
operation can be obtained without significant degradation of downstream rates.1
Field testing over the PSTN using full-duplex PCM indicates that the majority of lines tested can
support 40 kbit/s in the upstream direction.
Comparing the prototype to a V.34 receiver and transmitter, the prototype digital modem receiver is
less complex, and the prototype analog modem transmitter is slightly more complex (about 3 MIPS
more).
The following results were generated using TAS Digital Series 2 – DTNE network simulator
equipment.2 TAS Digital Series 2 allows the tester to inject noise independently in either
downstream or upstream directions since the noise is injected in the 4-wire path. Hence, the noise is
injected after the loop in the upstream direction and before the loop in downstream direction.
Tests were conducted to demonstrate the impact of standard EIA local loops, channel noise, and
trans-hybrid loss on the upstream performance.
All tests were conducted with digital modem transmit power set to -12 dBm. Downstream direction
was configured for no digital impairments and no noise. Upstream direction was configured with no
digital loss.
Figure 1 shows upstream performance over the standard EIA local loops. There is one RBSimpacted slot in the upstream direction. Noise is set at constant level of 22 dBrn. It is important to
note that resulting SNR3 will decrease as the loop is varied from Null to EIA5 since the signal
power decreases but the noise power remains constant. Trans-hybrid loss is set at constant level of
21 dB while the loop is varied from Null to EIA5.
Figure 2 and 3 show upstream performance relative to channel noise over the standard EIA2 loop.
There is one RBS-impacted slot in the upstream direction. SNR is calculated based on the received
signal power and the noise power. Figure 2 shows the connection rates while figure 3 shows the
throughput.
Throughput was measured using Pro-Comm software utility. Modems were configured for LAPM
with block size of 256 bytes and no data compression option. File transfer test was conducted with
a file size of 509,766 bytes.
1
Speeds in the downstream direction have not been fully optimized in the prototype modems. We believe that higher
downstream speeds will be easily achievable without any impact on the performance in the upstream direction after
minimal tuning.
2
TAS Series 2 - DTNE has 8 missing codes in the first mu-law quantization segment of the upstream codec. This
deficiency impairs performance in the upstream direction.
3
Received analog modem signal power to noise ratio.
2
Figure 4 shows upstream performance relative to trans-hybrid loss over the standard EIA2 loop.
There is one RBS-impacted slot in the upstream direction. Trans-hybrid loss is varied from 21 to 0
dB.
Test Configuration:
Noise: 22dBrn
DPCM Transmit Level: -12dBm
Trans Hybrid Loss : 21dB
Upstream Digital Impairments: RBS in 1 slot of 6
Downstream Digital Impairments: None
Performance Over Standard Local Loops
APCM TX @ -12dBm
48.0
46.7
Upstream Rate (kbit/s)
45.3
NULL
44.0
NULL
EIA1
EIA1
EIA2
EIA3
EIA4
EIA5
42.7
41.3
APCM TX @ -12dBm
APCM TX @ -16dBm
44
41.3
42.6
38.6
41.3
37.3
40
37.3
EIA2
38.6
36
37.3
33.3
EIA3
40.0
EIA4
38.7
EIA5
37.3
36.0
APCM TX @ -12dBm
TX= -12dBm
Bitrate (kbit/s)
Loop:
NULL
EIA1
EIA2
EIA3
EIA4
EIA5
Upstream
44.0
42.6
41.3
40.0
38.6
37.3
Downstream
50.6
50.6
50.6
50.6
50.6
45.3
Figure 1
3
Test Configuration:
Local Loop: EIA2
DPCM Transmit Level: -12dBm
Trans Hybrid Loss : 21dB
Upstream Digital Impairments: RBS in 1 slot of 6
Downstream Digital Impairments: None
Performance with Noise
(Loop EIA2)
APCM TX @ -12dBm
28.0
Upstream Rate (kbit/s)
44.0
42.7
41.3
40.0
38.7
37.3
36.0
34.7
33.3
32.0
30.7
29.3
28.0
26.7
25.3
24.0
31.0
34.0
37.0
40.0
43.0
46.0
49.0
(Upstream RX Signal / Noise) SNR (dB)
Noise Level
(TAS-dBrn)
22
25
28
33
35
38
40
42
44
RX Lvl - (dBm)
Received Bitrate (kbit/s) bytes/s
Bitrate (kbit/s)
Upstream
Downstream
SNR (dB) Upstream
51.3
41.3
50.6
5044
48.3
40.0
50.6
4915
45.3
38.6
50.6
4788
40.3
37.3
50.6
4565
38.3
37.3
50.6
4488
35.3
34.6
50.6
4263
33.3
33.3
50.6
4000
31.3
30.6
50.6
3737
29.3
28.0
50.6
3390
-16.7
Figure 2
4
52.0
SNR
dB
5
4
4
Test Configuration:
Local Loop: EIA2
DPCM Transmit Level: -12dBm
Trans Hybrid Loss : 21dB
Upstream Digital Impairments: RBS in 1 slot of 6
Downstream Digital Impairments: None
Protocol: LAPM, Data compression off, block size is 256 bytes
Flow Control: XON/XOFF
File Size: 509,766 bytes
Performance with Noise
(Loop EIA2)
Upstream Throughput (byte/s)
APCM TX @ -12dBm
5000
4500
4000
3500
3000
28.0
31.0
34.0
37.0
40.0
43.0
46.0
49.0
(Upstream RX Signal / Noise) SNR (dB)
Noise Level
(TAS-dBrn)
22
25
28
33
35
38
40
Received Bitrate (kbit/s) bytes/s
Bitrate (kbit/s)
Upstream
Downstream
SNR (dB) Upstream
51.3
41.3
50.6
5044
48.3
40.0
50.6
4915
45.3
38.6
50.6
4788
40.3
37.3
50.6
4565
38.3
37.3
50.6
4488
35.3
34.6
50.6
4263
33.3
33.3
50.6
4000
42
31.3
30.6
3737
50.6
44
29.3
28.0
3390
50.6
RX Lvl - (dBm)
-16.7
Figure 3
5
52.0
Test Configuration:
Local Loop: EIA2
Noise: 22dBrn
DPCM Transmit Level: -12dBm
Upstream Digital Impairments: RBS in 1 slot of 6
Downstream Digital Impairments: None
Performance with Echo
(Loop EIA2)
APCM TX= -12dBm APCM TX= -16dBm
Upstream
Upstream Rate (kbit/s)
SER(dB)
20.3
16.2
12.9
9.4
6.1
2.6
-0.4
-3.4
45.3
44.0
42.7
41.3
40.0
38.7
37.3
36.0
34.7
33.3
32.0
30.7
29.3
28.0
0
3
SER(dB)
41.3
40.0
40.0
40.0
38.6
37.3
34.6
32.0
APCM
Upstream TX @ -12dBm
16.3
12.2
8.9
5.4
2.1
-1.4
-4.4
6
38.6
37.3
36.0
33.3
32.0
30.6
29.3
9
12
15
Trans-hybrid Loss (dB)
Trans Hybrid Loss
APCM TX @ -12dBm
Bitrate (kbit/s)
Rejection Setting (dBm)
Upstream
Downstream
41.3
40.0
40.0
40.0
38.6
37.3
34.6
32.0
21
18
15
12
9
6
3
0
Figure 4
6
50.6
50.6
50.6
50.6
50.6
50.6
50.6
50.6
18
21