Abis Over IP/Abis Optimization on-site Workshop

Abis Over IP/Abis Optimization
on-site Workshop

01/038 13 - LZU 108 6787 Uen Rev A Ericsson AB 2007 Abis Over IP/Abis Optimization on-site Workshop 2007-01-15
1
Objectives
On completion of this course the participants will be able to:
 Recognize new system architecture
 Understand the dimensioning rules using the Abis planning tools
 Activate the Abis over IP
 Activate the Abis Optimization
 Use the Performance Monitoring

2
Architecture for Abis Optimization

3
Bandwidth Optimization
 Discontinuous transmission (DTX) is a mechanism that allows the radio
transmitter to be switched off during speech pauses.
 Discontinuous transmission needs to be activated in both UL and DL to be
able achieve bandwidth saving.
 Erlang aggregation gain is achieved from sector cells.
 This gain is depending on the type of area the sectors are covering and
grade of service in cells but measurements have shown a gain between
10-20%.
 No static allocation of transmission for GPRS/EGPRS is needed.
 Air TS capable of EGPRS and CS3/CS4 does not need any fixed
allocated bandwidth.
 Instead GPRS/EGPRS will use available transmission on the super
channel.
 Redundant information is removed from GPRS/EGPRS frames.
 Redundant information is removed from AMR frames.
 The LAPD RSL and OML signaling is more efficiently used on Abis.

4
Hardware Compatibility-BSC
 BSC configurations with AXE810 hardware and BYB
501 with NNRP-4 and NNRP-5 are supported.
 The Packet Gateway (PGW) based on RP HW, is
needed in the BSC to support Abis Optimization.
 No automatic PGW redundancy is supported.
 The Gigabit Ethernet Switch Board (GESB) are used to
connect ethernet of multiple GEM magazines of packet
gateways and multiple magazines of PCU on GPH RP.
 SCB-RP/3 are needed for magazine ethernet switching

5
Transmission Requirements
 Supports both E1 and T1 transmission.
 The BSC also supports ET155 (STM-1 and OC-3).
 Supports Ericsson's DXX solution provides time slot
integrity as well as their MINI-link products.

6
Supported RBS Hardware Configurations
 Base stations with DXU-21/IXU-21
 RBS2106, 2107, 2109, 2112, 2206, 2207, 2308, 2309
are supported together with Abis Optimization.
 Mixed Micro and Mixed HW configurations are not
supported together with Abis Optimization.

7
Features Compatibility
 Terrestrial Link Supervision
– Terrestrial link supervision [at 16 kbit/s] is replaced by
supervision of super channels.
 Interface over Satellite
– The feature Interface over Satellite is supported together
with Abis Optimization (with the same limitations as without
Abis Optimization).
 Abis Triggered HR Allocation
– Abis Triggered HR Allocation is supported.
 Fullrate AMR on 8 kbps Abis
– Fullrate AMR on 8 kbps Abis is supported.

8
 Cascaded Sites
– Base stations in cascade is supported to the same level as
previously.
– A BTS using Abis Optimization can only be cascaded
through a DXU-21/IXU-21 based BTS
 DIP Supervision
– DIP supervision is supported.
 Flexible Abis
– Flexible Abis can not be used together with Abis
Optimization for the same TG.

9
 LAPD Concentration and LAPD Multiplexing
– LAPD Concentration and LAPD Multiplexing is not possible to
combine with Abis Optimization.
 Semipermanent Connected Transcoders
– Semipermanent connected transcoders are not supported
together with Abis Optimization.
 OMT
– The Remote OMT over IP (ROMT/IP) has the same functionality
as the locally connected OMT and is supported.
 Dedicated Packet Data Channels
– With Abis Optimization, all traffic and signalling share the same
super channel between the BSC and the BTS.

10
Dimensioning Strategy
 To maintain good speech quality the packet drop rate
caused by Abis Optimization must be kept below a
certain limit.
 This means that the average load on the super channel
must be kept below a certain percentage limit.
 Maintaining packet drop rate below 1x10-4.

11
Max load on a SC dimensioned for n calls

12
Bandwidth utilization of the super channel

13
SC Dimensioning
 BTS Site Configuration
– TRXs
– E-TCHs
– Fixed PDCHs
– Control channels
 Traffic Model
– VAF (%)
– Max % HR in TG
– % AMR in TG
– Erlang Aggregation Gain

14
Voice Activity Factor (VAF (%))
 VAF [%] for AMR FR = 100 * (TFV3TFCMx /
TFV3CMxUL) where x is codec mode 1-4
 VAF [%] for AMR HR = 100 * (THV3TFCMx /
THV3CMxUL) where x is codec mode 1-4
 VAF [%] for FR = 100 * (TFV1FERTF /
(50*MP*TFV1TRALACC / TFV1NSCAN))
 VAF [%] for EFR = 100 * (TFV2FERTF /
(50*MP*TFV2TRALACC / TFV2NSCAN))
 VAF [%] for HR= 100 * (THV1FERTF /
(50*MP*THV1TRALACC / THV1NSCAN))

15
SC Dimensioning
 Abis Opt Configuration
– Full Rate AMR on 8kbps Abis
– Dynamic HR Allocation
– Dynamic FR/HR Mode Adaptation
– GPRS Bandwidth [kbit/s]
 Outcome
– Size of the SC

16
Dimensioning Example
 TRXs: 12 TRXs on the SC
 E-TCHs: 4 EDGE capable TCHs
per sector.
 Fixed PDCHs: 3 fixed E-PDCHs
are used
 Control channels: 1 BCCH and
2 SDCCH/8 per sector
 VAF (%): 60%.
 Max % HR in TG: 50 % half rate
 % AMR in TG:80%
 GOS in TG and cell: 1%
 GPRS Bandwidth [kbit/s]: 256
kbit/s allocated for
GPRS/EGPRS
BTS Site Configuration Abis Opt Configuration
Sector 1 Sector 2 Sector 3
TRXs
E-TCHs
Fixed PDCHs
Control chan. GPRS Bandwidth [kbit/s]
Traffic Model Results
22 E1/T1 TS is required with Abis opt.
VAF (%)
40 E1/T1 TS is required with TDM mode and
Max % HR in TG LAPD Concentration 4:1 and without flex Abis.
% AMR in TG
Recommended parameter values:
SDAMRREDABISTHR = 71%
GOS in TG 0,5% SDHRAABISTHR = 74%
GOS in Cell 1,0% SDFRMAABISTHR = 81%
Erlang aggr. Gain 11%
0,01%
0,05%
0,1%
0,5%
Abis Optimization Dimensioning
Full Rate AMR on 8 kbps Abis
Dynamic HR allocation
Dynamic FR/HR mode adaptation
60
80
256
50
4 4 4
6 6 6
1 1 1
2 2 2
Abis Triggered HR Allocation

17
Bandwidth saving examples
RBS Configuration
Number of TRXs
in cell A+B+C
Number of Abis TS
required without Abis
Optimization (LAPD
Conc and no Flexible
Abis)
Number of Abis
TS required with
Abis Optimization
Bandwidth saving
for the RBS
4+4+4 34 19 44%
3+3+3 28 15 46%
2+2+2 21 10 52%
12+0+0 30 22 26%
8+4+0 32 20 37%

18
BTS site example with one super channel
handling 12 TRXs

19
BTS site example with two super
channels handle 12 TRXs

20
Implementing
 Enabling The Feature
– SYPAC:access=enabled,psw=psw2par;
– DBTRI;
– DBTSC:tab=axepars,setname=cme20bscf,name=abisopt,v
alue=1;
– DBTRE:com;
– BTS software shall be TSSG12R9 or later.
– RXMOC:mo=rxotg-162,swver=TSSG12R9;

21
Changing transmission mode
Changing transmission mode for a TG from TDM mode to
Abis Optimization
 Remove the digital paths.
– RXMOP:MO=RXODP-162-0;
– DTDIP:DEV=RXODPI-162; !dev from rxmop
– DTBLI:DIP=162DP; !dip from dtdip
– DTDIE:DIP=162DP; !dip from dtdip
– RXAPP:MO=RXOTG-162;
– RXAPE:MO=RXOTG-162,DCP=ALL;
– RXMOE:MO=RXOCON-162;
– RXMOC:MO=RXOTG-162,ABISALLOC=FIXED;
– RXMOC:MO=RXOCF-162,SIG=SCCONC;

22
Implementing
 Associate TRX's with DCP's.
 Same DCP values shall be reused for each TG.
– RXMOC:MO=RXOTRX-162-
0,SIG=SCCONC,DCP1=178,DCP2=179&&186;

23
Initiate a super channel group and
its super channels
 The devices used in the semi-permanent connection
must be manually blocked first.
– BLODI:DEV=RTPGD-1&&-10;
– BLODI:DEV=RBLT2-1&&-10;
– RRSGI:SCGR=162,MODE=SCM;
– RRSCI:SCGR=162,SC=0,DEV=RTPGD-1,DEV1=RBLT2-
1,DCP=1,NUMDEV=10; !RBLT2,
 DCP and numdev values can be reused from RXAPP
 Associate the TG with the SCGR.
– RXMOC:MO=RXOTG-162,SCGR=162;

24
Associate the TRXs with super channels
 RXMOC:MO=RXOTRX-162-0,SC=0;
 RXMOC:MO=RXOTG-162,TMODE=SCM;
 RXMOI:MO=RXOCON-162,DCP=350&&581;

25
Associate a number of RTPGD
devices to TG
 Associate a number of RTPGD devices to TG
depending of the size of the TG. Unblock the devices.
– RXAPI:MO=RXOTG-162,DEV=RTPGD-20&&-40;
– BLODE:DEV=RTPGD-20&&-40;
 If E-GPRS PDCH' are wanted 64k devices needs to be
allocated. Add parameter RES64K to command RXAPI
for as many devices needed to be 64k capable.
 Each PGW individual is capable of 767 RTPGD
devices.
– RTPGD 0 .. 767 -> PGW individual 0 RTPGD 768 .. 1535 ->
PGW individual 1 ...

26
Supervision Of Super Channel
 Quality Supervision
 Fault Supervision
 Related Statistics

27
Impact on Legacy Counters
 GPRS/EGPRS throughput counters
 Cell congestion counters

28
Statistics for Performance Management
 KBSENT: Number of kbytes sent DL by PGW during last recording
period.
 KBREC: Number of kbytes received UL by PGW during last
recording period.
 KBSCAN: Number of scans for number of kbytes sent and
received by the PGW.
 To be able to detect any traffic peaks, the following counters are
used with Abis Optimization:
 KBMAXSENT: Maximum number of kbytes per second sent DL by
the PGW during the last 15-minute interval.
 KBMAXREC: Maximum number of kbytes per second received UL
by the PGW during the last 15-minute interval.

29
Statistics for Performance Management
 THRULPACK: Number of discarded frames in the UL
by the DXU due to Abis overload during last recording
period (normally 15 minutes).
 THRDLPACK: Number of discarded frames in the DL
by the PGW due to Abis overload during last recording
period (normally 15 minutes).
 LOSTULPACK: Number of lost frames on the UL
during last recording period (normally 15 minutes).
 LOSTDLPACK: Number of lost frames on the DL
during last recording period (normally 15 minutes).

30
Abis Load Regulation and Overload
Handling
 Allocate half rate speech calls by triggering the feature
"Abis triggered HR Allocation".
 Move full rate speech calls to half rate by triggering the
feature "Abis triggered HR Allocation".
 Trigger the feature "Fullrate AMR on 8 kbps Abis". This
feature allocates full rate AMR calls with codecs
restricted to a maximum of 7.4 kbps.

31
How to detect when to change super
channel size
 If the Abis link is continously overloaded new call set up
will be rejected. This can be seen by the congestion
counters THTCONGS and TFTCONGS. Note that the
counters are triggered by both cell congestion and Abis
congestion.
 Abis overload can also be seen on the counters
THRULPACK and THRDLPACK. If these counters
indicates a frame loss of more than 1*10-4, this might
impact speech quality. If THRULPACK / (KBREC *
1000 / 35) or THRDLPACK / (KBSENT * 1000 / 35) >
1*10-4 then consider increase the super channel size.

32
Link Quality
 BER Performance for the Abis Interface
 For voice traffic:
– at a constant BER of 1x10-4 the system is working but the
speech quality will be bad.
– at a constant BER of 1x10-5 the system is working, the
speech quality will be good and this BER level is sufficient
for normal operation.
– at a constant BER of 1x10-6 the system works satisfactory.
 For GPRS traffic:
– at a constant BER of 1x10-4 the system is working and the
throughput is good.

33
Troubleshooting
 If the TG is not working as it should here are some trouble
shooting hints.
 If the state of the CF is NOOP
 Check the state of the superchannel.
 RRSCP:SCGR=<scgr>;
– If the state of the superchannel is 'FLT' Then there might be a fault
in the BSC, TSS or the interconnecting transport network.
 Check the BSC
 Print the state of the SNT. For RTPGD devices 0-767 the SNT is
RTPGS-0.
 NTSTP:SNT=RTPGS-<n>;
– If the state of the SNT is 'AB', block and subsequently deblock the
SNT with NTBLI/NTBLE.
– If the state of the SNT is 'MB', deblock the SNT with NTBLI.
– If the state of the SNT is 'CB', check the state of the EM.

34
Troubleshooting
 Print the state of the EM.
 EXEMP:RP=<rp>,EM=ALL;
– If the state of the EM is 'AB', block and subsequently deblock the
EM with BLEMI/BLEME.
– If the state of the EM is 'MB', deblock the EM with BLEME.
– If the state of the EM is 'CB', check the state of the RP.
 Print the state of the RP.
 EXRPP:RP=<rp>;
– If the state of the RP is 'AB', block and subsequently deblock the
RP with BLRPI(forced)/BLRPE.
– If the state of the RP is 'MB', deblock the RP with BLRPE.
 Check TSS and interconnecting transport network
 Find the serving E1/T1(DIP)
 NTCOP:SNT=ALL,DIPINF;

35
Troubleshooting
 Print the state for the DIP(s) used by the devices printed by
RRSCP.
 DTSTP:DIP=<dip>;
– If the state is 'AB' then there is a fault in the interconnecting
network or the TSS is shut down.
– If the superchannels are ok then check the abis paths.
 Print the abis paths.
 RXAPP:MO=RXOTG-<n>;
 Print the state of the RTPGD devices from RXAPP.
 STDEP:DEV=RTPGD-<a>&&-<b>;
– If the state of the devices are 'MBL' then deblock the devices.

36
Troubleshooting
 BLODE:DEV=RTPGD-<a>&&-<b>;
 Find the RHDEV device and print its state.
 RAPTI:DEV=RTPGD-<cf rtpgd dev>;
 STDEP:DEV=RHDEV-<cf rhdev dev>;
– If the state is 'CBL' the TRH RP is probably blocked.
 Check the TSS configuration.

38
Architecture for Abis over IP

39
PGW - STN - BTS protocol view

40
O&M Network Topology

41
BSC Hardware
 Abis over IP is supported by BSC configurations with
AXE810 hardware and BYB 501 with NNRP-4 and
NNRP-5.
 A hardware in the BSC, the PGW, The PGW - STN
transmission is using IPv4 and L2TP.
 BSC supports up to 64 PGW RPs.
 One PGW RP supports 50 TRXs
 One STN supports one TG

42
PGW –ABIS over IP
 The PGW handles speech, GPRS/EGPRS and
signaling in the same piece of hardware.
 In the uplink direction the PGW will receive LAPD
frames from the BTS packed into IP packages by the
STN
 In the downlink direction, the PGW will receive frames
from TRA or TRH via the GS interface

43
PGW –ABIS over IP
 The IP bundling algorithm is configurable.
– The operator can adjust the behavior per PGW - STN link
– There are parameters for :
 maximum packet size
 maximum waiting time
 frame drop rate

44
IP/L2TP Overhead
 Large IP packets will decrease the IP/L2TP overhead but increase
the delay depending on the time needed to collect a large number
of frames.
 Large IP packets will also increase the probability that the packet
is dropped due to bit errors in the transmission.
 Small IP packets will increase the IP/L2TP overhead but decrease
the delay depending on the time needed to collect the necessary
frames.
 Small IP packets will also decrease the probability that the packet
is dropped due to bit errors in the transmission.
 A short waiting time will increase the IP/L2TP overhead depending
on the amount of traffic but decrease the delay.
 A long waiting time will decrease the IP/L2TP overhead depending
on the amount of traffic but increase the delay.

45
Traffic Types mapped with LAPD SAPI
 It is possible to use different DiffServ codes for each
existing different traffic types.
 The traffic type is defined by its SAPI value.
 In the BSS the following SAPI values are used over
Abis:
– 0, RSL
– 10, Speech
– 11, CS Data
– 12, GPRS/EGPRS
– 62, OML

46
RBS Hardware
 Abis over IP is supported by RBS 2308 base stations.
 A hardware the PSTU is introduced in the BTS to
implement the STN node.
 Abis over IP will be available for Macro Q2/2006

47
BTS-STN
 A fixed configuration of the E1 interface between BTS-
STN is used.
 4 super channels are used .
 TS 1 to 31 are used on all super channels.
 The TRXs have a fixed connection to the super
channels. TRXs with TEI value 0 to 2 are connected to
superchannel 0. TRXs with TEI value 3 to 5 are
connected to superchannel 1 and so on.
 Super channel 0 is connected to port A on the IXU,
super channel 1 is connected to port B and so on.

48
STN-PSTU
 The STN has an Ethernet interface towards the PGW
and 4 E1s configured as super channels towards the
BTS.
 In the downlink direction, the STN unpacks the IP
packets received on the Ethernet interface.
 In the uplink direction, LAPD frames from the BTS are
received on the super channel in LAPD format.
 The bundling of LAPD frames into IP packets works as
in the PGW.
 STN is represented by the PSTU hardware as an
integrated part of the BTS.

49
Overload Handling
 The operator defines thresholds, as a percentage of
engineered bandwidth, for the Abis load per TG.
 The following Features are aplied to high-load control:
– Abis triggered HR Allocation
– Fullrate AMR on 8 kbps Abis

50
Supervision of BSC - STN Link
 The STN sends a keep-alive message to the BSC on a
periodic basis.
 The period is configured.
 If an answer is not received an alarm is raised to OSS
and the STN tries to re-establish the connection.
 When the connection is re-established the alarm is
ceased.

51
STN O&M model

52
STN O&M
 STN Configuration
– Element Management
– Through OSS
 Fault Management
 Performance Management
– STN collects performance events
– The sampling period is 15 minutes
 STN software management
– Software inventory
– Software upgrade
– Request activation
– Administrative information

53
STN Parameter Configuration from BSC
 The following parameters are transferred from the BSC
to the STN after connection establishment:
– DiffServ Code per traffic type
– IP packaging parameters
– packet size
– waiting time
– CRC-32 check
– Overload threshold

54
Synch distribution over IP network
IP
Transport
Service
BSC/RNC
Remote area
Time server
Time server

55
Problem and solutions
 Problem: Normal RBS synchronization using E1/T1 not
available with IP transport.
 Solutions:
– Use GPS, same solution as for synchronized radio
networks.
– Distribute synch over the IP network

56
Synch distribution over IP network
 Synchronization of RBSs based
on standard NTP protocol
– Distributed architecture with
multiple time servers to
accommodate varying
transport network
characteristics.
– Variable rate of timing
packets as required by the
different RBSs.
– Common solution with
WCDMA, the same pool of
time servers can be shared.
IP
Transport
Service
BSC/RNC
Remote area
Time server
Time server

57
Synch distribution (cont.)
 Solution based on standard NTPv3
– Enables use of standardized timing infrastructure.
– Client (RBS) controlled rate of timing packets to accommodate
different network characteristics and to minimize O&M of time
server.
 Synch recreated at RBS by special Ericsson algorithm
– Algorithm based on Ericsson IP
– Specially adopted to RAN requirements
– Time to synch and synch retention capability depends on
network characteristics, especially delay variation distribution
 RBS holdover used to cope with temporary network
outages and characteristics problems

58
Requirements on IP synch
 The ability to obtain synch over IP is based on two
factors:
– The stability of the local oscillator
– The delay distribution of the incoming NTP packets
 For the 06A PSTU the requirement is that at least the
least delayed 1% of the NTP packets shall arrive within
a 20us delay window.
– Network req. At least 10% within 120 uS
– Time server req: At least 10% within 10 uS

59
Abis Over IP Transport Network
Dimensioning

60
Dimensioning Parameters
 Site Parameters
– TRXs. The number of TRXs in the site.
– E-TCHs. This is the number of EGPRS TCHs
– Control channel. The number of time slots used for BCCH and
SDCCH.
 Traffic Parameters
– Speech activity.
– Codec.
– Packing.
– Bundling time.
 SLA Parameters
– Minimum delay,
– Delay variation,

61
Dimensioning Example 1
 TRXs: 4
 E-TCHs: 2
 Control chan.: 2
 Speech activity: 60%
 Codec: FR
 Packing: 1
 Bundling time: 1 ms
 Minimum delay: 2 ms
 Delay variation: 1 ms
Abis over IP network dimensioning
Input
TRXs 2
E-TCHs 2 [air timelots]
Control chan. 1 [air timelots]
Voice Activity Factor 50%
Codec AMRFR FR,EFR,HR,AMRFR,AMRHR
Optimization 1 0 if frame optimization is not used, 1 if used
Bundling time 1 [ms]
SLA
Minimum delay 1 [ms]
Delay variation 1 [ms]
Output
Minimum IP bandwidth 430 [kbit/s]
Choose:
IP bandwidth [kbit/s] 256 512 1024 2048 10000 513
total delay [ms] - 12 6 4 3 12
Jitter buffer setting [ms] - 11 5 3 2 11
PTA setting - 6 3 2 2 6

62
Example 1 (cont.)
 The result is then:
 The lowest possible bandwidth is 693 kbit/s for not risking a overload
that could lead to loss of the cell. If using a 1024 kbit/s transmission,
the resulting total delay is 10 ms. The recommended minimum PTA
value to use is 5. The recommended minimum jitter buffer setting is
8. This network will result in performance close to TDM mode.
Output
Minimum IP
bandwidth
692.8 [kbit/s]
IP bandwidth
[kbit/s]
256 512 1024 2048 10000
total delay - - 10 6 4
Jitter buffer
setting [ms]
- - 8 4 2
PTA setting - - 5 3 2

63
Example 2
 TRXs: 1
 E-TCHs: 2
 Control chan.: 2
 Speech activity: 60%
 Codec: AMRHR
 Packing: 1
 Bundling time: 5 ms
 Minimum delay: 10 ms
 Delay variation: 5 ms

64
Spread sheet output from example 2
Output
Minimum IP
bandwidth
253.6 [kbit/s]
IP bandwidth
[kbit/s]
256 512 1024 2048 10000
total delay 35 27 23 21 20
Jitter buffer
setting [ms]
25 17 13 11 10
PTA setting 16 12 11 10 9

65
IP Addressing
 There are several types of IP traffic terminated in the BSC.
 These traffic types are separated into several subnets, one per traffic
type. One of the subnets is the AbisIP network. A dedicated subnet-based
VLAN is configured in the BSC LAN Switches to carry the Abis over IP
traffic to/from the STN at BTS site.
 A public subnet with one IP address per RP running Abis over IP (PGW)
and one IP address for each of the two BSC LAN switches is required.
 The logical connection towards the site routers is called SR_Abis in the
BSC LAN Switches. It requires one IP address per BSC LAN switch.
 One extra IP address may be required if VRRP is used for site integration.
All payload and signaling traffic in and out from the BSC will use the same
physical port on the BSC LAN Switches.
 It shall be noted that except where external VLAN tagging is enabled in
the configuration, all VLANs are internal to the BSC LAN switches.

66
Understanding Abis/IP performance
 Introducing Abis over IP makes the relation between
Abis transmission and overall system characteristics
more complicated. BSS system characteristics is
dependant on:
– IP network characteristics
– Configurable system parameters
 There is a trade-off between bandwidth requirements
and characteristics

67
IP network characteristics
 IP network have a different set of characteristics
compared to TDM:
– IP network delays are significant compared to TDM delays
and also varies greatly from one network to another
– Bit errors in underlying transmission ends up as dropped
packets, not as faults in payload
– Packet drop rate and delay varies over time and typically
depends on network load
– Even in normal network situations packet delay variation
(jitter) occur and must be handled
– Short breaks (~5-10 s) in service not uncommon due to re-
routing etc.
– End-to-end available bandwidth is not obvious and may
vary over time

68
Packet delay and delay variation
Time
Probability
Tmin Tmax
delay Delay variation
 To be able to smoothly stream data all packets are
delayed Tmax by the jitter buffers
 Packets arriving after Tmax are in effect lost
 Tmax (delay plus jitter) is the limiting characteristic

69
Packet drop rate
 Packet drop is caused by a number of factors:
– Bit errors in transmission
– Congestion on intermediate links in the network
– Overload in the intermediate routers
 Drop rate is load dependant
– On the load on the path from RBS to BSC
– On the load on the network as a whole

70
Abis delay
 The delay from the RBS to the transcoder or PCU in
the BSC (or the other way around) depends on a
number of factors:
– Processing delay in the RBS/PSTU and BSC, ~0.5-15 ms
– IP network delay
– Size of jitter buffers, 1-255 ms
– Bundling time, typically 1-5 ms
 Delay for speech will increase compared to TDM, delay
for GPSR/EDGE can be maintained with a good
enough IP network

71
Speech Delays vs.
Subjective Voice Quality
One way speech delay effect on perceived quality, with 30-72 ms added delay (MS-to-MS)

72
Implementing
Enable feature
– SYPAC:access=enabled,psw=psw2par;
– DBTRI;
– DBTSC:tab=axepars,setname=cme20bscf,name=abisip,value=1;
– DBTRE:com;
– BTS software shall be TSSG12R9 or later.
– RXMOC:mo=rxotg-162,swver=TSSG12R9;
Changing transmission mode for a TG from TDM mode to Abis over IP
– RXAPE:MO=RXOTG-162,DCP=ALL;
– RXMOE:MO=RXOCON-162;
– RXMOC:MO=RXOTG-162,ABISALLOC=FIXED;
– RXMOC:MO=RXOCF-162,SIG=SCCONC;

73
Associate each TRX with DCP's.
 The DCP-values are fixed and are reused for each TG configured
with Abis over IP.
 Same DCP values shall be reused for each TG.

74
Define PSTU in BSC
 RRPTI:PSTU=TG162;
 For each TG a superchannel group (SCGR) with four
superchannels (SC) shall be defined.
 RRSGI:SCGR=162,MODE=IPM,PSTU=TG162,MBWD
L=64,MBWUL=64;
 RRSCI:SCGR=162,SC=0&1&2&3;

75
Associated the TG with the SCGR
 RXMOC:MO=RXOTG-162,SCGR=162;
TRX SC
0..2 0
3..5 1
6..8 2
9..11 3

76
Associated the TG with the SCGR
 RXMOC:MO=RXOTG-162,TMODE=SCM;
 RXMOI:MO=RXOCON-162,DCP=350&&581; ! The
DCP values are fixed and are reused for each TG
configured with Abis over IP ;

77
Verify that IP Gateways are configured
correctly
 RRGWP, RRGWC
 Add a IP address of fixed type and associate it with the
PGW.
– RRIPI:IPADDR=172.30.85.48,IPDEVTYPE=RTIPPGW,IPD
EVNO=0,MASK=255.255.255.0,GW=GW1;
 Associate application Abis over IP (ABI) with created IP
address
– RRAPI:IPADDR=172.30.85.48,APL=ABI;
 Allocate a number of RTPGD devices to TG depending
of the size of the TG (use approx 9 devices for each
TRX's).
– RXAPI:MO=RXOTG-162,DEV=RTPGD-20&&-40

78
TERDI/TELNET
 To verify that the configuration is correct and
downloaded to PGW use terdi or telnet to log in to the
RP and execute command:
 apt abisip get tginfo all.
 TSS/LTE/MobCtrl Specifics

79
TG-RBLT Association
 The first Abis over IP TG shall have DEV1 set to RBLT-
32. The next one to RBLT-32 + 128 = RBLT-160
 RXMOI:MO=RXOTG-162,TYPE=1,DEV1=RBLT-
32,RSITE=RSITE_162;
 RXMOI:MO=RXOTG-163,TYPE=1,DEV1=RBLT-
160,RSITE=RSITE_163;

80
General Tips and Info:
Print gateways ip-addresses.
 RRGWP;
Configuration when one LAN switch present:
 RRGWC:GW1=192.168.0.1,GW2=192.168.0.129;
Configuration when Two LAN switches present:
 RRGWC:GW1=192.168.0.1,GW2=192.168.1.1;

81
Apt commands
 apt abisip ?
 'abis' Available APT commands for 'Abis Over IP'
 apt abisip get jitterd -Prints jitter buffer data
 apt abisip set jitterd [ ? ] -Help for jitter data settings
 apt abisip get jitterbufferstat [ ? ] -Help for jitter buffer statistic
 apt abisip get tginfo [ ? ] -Help for 'get tginfo'
 apt abisip get pstuinfo[ ? ] -Help for 'get pstuinfo'
 apt abisip get l2tpsessions -Sessions per TG and controll connection
 apt abisip set dbglevel [ ? ] -Print the help for how to set the debug level for
the L2TP api.

get tginfo - prints the tg configuration get pstuinfo get l2tpsessions - prints current
L2TP sessions. If all sessions are setup sucessfully every
 set dbglevel - sets debuglevel in the L2TP API. Useful for debugging the API.

82
Related Statistics
Impact on Legacy Counters
 GPRS/EGPRS throughput counters
 Cell congestion counters

83
Counters for monitoring BSC - STN link
Name Description
IPSENTKBYTES Accumulated number of sent kilobytes by the PGW.
IPRECKBYTES Accumulated number of received kilobytes by the PGW.
IPLOSTPACKUL Number of lost packages in UL.
IPNUMSCAN Number of scans of the ABISIP counters.
IPULRECPACK Number of packets received UL on the PGW - STN IP link.
IPDLSENTPACK Number of packets sent DL in the PGW - STN IP link.

84
STN Counters
 ipInReceives
 ipInHdrErrors
 ipInAddrErrors
 ipInUnknownProtos
 ipOutRequests
 ifInUcastPkts
 ifInBroadcastPkts
 ifInMulticastPkts
 ifOutUcastPkts
 ifOutBroadcastPkts
 ifOutMulticastPkts
 inAbisOctets
 outAbisOctets
 inAbisPackets
 outAbisPackets
 inAbisPacketsErrors
 PGW_PSTU_Network_Delay
 PGW_PSTU_Network_Delay
_StdDeviation

85
Monitoring of Time Server – STN Link
 TS_Delay_1
 TS_Delay_10
 TS_Delay_50
 TS_NoPkts

86
STN
Name Description
ifOutErrors
Number of outbound packets that contained error
preventing them from being deliverable to higher-
layer protocol.
ifInOctets
Total number of octets received on the interface,
including framing characters.
ifOutOctets
Total number of octets transmitted on the
interface, including framing characters.
Number of inbound packets that contained error
preventing them from being deliverable to higher-
layer protocol.
ifInErrors

87
Main Controlling Parameters in BSC
Parameter Name
Default
Value
Recommended Value Value Range
CRC32 ON ON ON/OFF
DSCPDL 0 0 0-63
DSCPUL 0 0 0-63
IPDEVNO - - 0-65535
IPDEV2NO - - 0-65535
IPDEVTYPE - RTIPPGW String 1-7
JBSDL 20 20 0-255
JBSUL 20 20 0-255
MBWDL - - 64-16384
MBWUL - - 64-16384
MCT 1 - jan/20
MODE - IPM IPM/SCM
MPS 1465 1465 300-1465
OVLTH 25 25 0-1000
PACKALG 1 1 0-1

88
Main Controlling Parameters in BSC (cont.)
Parameter
Name
Default
Value
Recommended
Value
Value
Range
PTA 7 - 0-63
PSTU - - String 1-20
SC - - 0-3
SCGR - - 0-511
SDAMRREDAB
ISTHR 100 70 1-100
SDFRMAABIS
THR 100 85 1-100
SDHRAABIST
HR 100 80 1-100
TMODE - SCM TDM/SCM

89
PTA
PTA
Numbe
r of
frames
Delay
(ms) PTA
Numbe
r of
frames
Delay
(ms) PTA
Numbe
r of
frames
Delay
(ms) PTA
Numbe
r of
frames
Delay
(ms)
0 1 4,6 16 18 83,1 32 52 240 48 120 553,8
1 2 9,2 17 20 92,3 33 56 258,5 49 128 590,8
2 3 13,8 18 22 101,5 34 60 276,9 50 136 627,7
3 4 18,5 19 24 110,8 35 64 295,4 51 144 664,6
4 5 23,1 20 26 120 36 68 313,8 52 152 701,5
5 6 27,7 21 28 129,2 37 72 332,3 53 160 738,5
6 7 32,3 22 30 138,5 38 76 350,8 54 168 775,4
7 8 36,9 23 32 147,7 39 80 369,2 55 176 812,3
8 9 41,5 24 34 156,9 40 84 387,7 56 184 849,2
9 10 46,2 25 36 166,2 41 88 406,2 57 192 886,2
10 11 50,8 26 38 175,4 42 92 424,6 58 200 923,1
11 12 55,4 27 40 184,6 43 96 443,1 59 208 960
12 13 60 28 42 193,8 44 100 461,5 60 216 996,9
13 14 64,6 29 44 203,1 45 104 480 61 224 1034
14 15 69,2 30 46 212,3 46 108 498,5 62 232 1071
15 16 73,8 31 48 221,5 47 112 516,9 63 240
Step Length 1 Step Length 2 Step Length 4 Step Length 8

90

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