Operator Logo ZGO-03-03-001 Full Dynamic Abis Allocation Feature Guide
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ZGO-03-03-001 Full Dynamic Abis Allocation
Feature Guide
ZGO-03-03-001 Full Dynamic Abis Allocation
ZTE Confidential Proprietary © 2010 ZTE CORPORATION. All rights reserved. I
ZGO-03-03-001 Full Dynamic Abis Allocation
Version Date Author Approved By Remarks
V1.00 2010-10-30 Not open to the Third Party
© 2010 ZTE Corporation. All rights reserved.
ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE.
Due to update and improvement of ZTE products and technologies, information in this document is subjected to change without notice.
ZGO-03-03-001 Full Dynamic Abis Allocation
ZTE Confidential Proprietary © 2010 ZTE CORPORATION. All rights reserved. II
TABLE OF CONTENTS
1 Feature Attribute ............................................................................................. 1
2 Overview ......................................................................................................... 1 2.1 Feature Introduction .......................................................................................... 1 2.2 Correlation with Other Features ........................................................................ 2
3 Technical Description .................................................................................... 2
4 Parameters and Configurations ..................................................................... 7 4.1 Parameter List .................................................................................................. 7 4.2 Parameter Configurations ............................................................................... 10
5 Related Counters and Alarms ...................................................................... 13 5.1 Related Counters ............................................................................................ 13 5.2 Related Alarms ............................................................................................... 13
6 Engineering Guide ........................................................................................ 13 6.1 Application Scenario ....................................................................................... 13 6.2 Configuration Description................................................................................ 15 6.3 Network Impact ............................................................................................... 15
7 Abbreviation .................................................................................................. 16
8 Reference Document .................................................................................... 16
ZGO-03-03-001 Full Dynamic Abis Allocation
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FIGURES
Figure 3-1 Use of Abis resources ......................................................................................... 3
Figure 3-2 Abis timeslot allocation ........................................................................................ 4
Figure 4-1 Parameter List ..................................................................................................... 7
Figure 4-2 Dynamic Abis configuration interface 1 ............................................................. 11
Figure 4-3 Dynamic Abis configuration interface 2 ............................................................. 12
Figure 4-4 Dynamic Abis configuration interface 3 ............................................................. 13
TABLES
Table 4-1 Parameter List .................................................................................................. 7
ZGO-03-03-001 Full Dynamic Abis Allocation
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1 Feature Attribute
iBSC version: [iBSC V6.20]
BTS version: [BTS V6.20 and Above]
Attribute: [Optional]
NEs involved:
NE Name Involved or Not Special Requirement
MS -
BTS √
BSC √
MSC -
MGW -
SGSN -
GGSN -
HLR -
Dependency: [None]
Mutual exclusion: [None]
Note: [None]
2 Overview
2.1 Feature Introduction
In the conventional way of Abis resource allocation, radio channels are bound fixedly with
Abis. Although this type of allocation improves service access efficiency, it results in
tremendous waste of Abis transmission resources and increase of access cost. To
improve utilization of Abis resources and guarantee service access efficiency, the
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dynamic Abis adopted by iBSC organizes Abis resources as resource pools. When a
service requests a speech or packet radio channel, appropriate Abis resource will be
allocated and bound dynamically with the allocated radio channel. When the radio
channel is released, the bound Abis resource is released at the same time, and returned
to the Abis resource pool.
The significance of dynamic Abis is to enable services to make full use of Abis
transmission resources when the Abis transmission bandwidth is fixed.
2.2 Correlation with Other Features
This function is only for the TDM based BTS and facilited with TDm transmission. For
those sites’ transmission based on IP or IP over E1 is not included.
3 Technical Description
The function implementation principles are as follows:
The dynamic Abis function is designed to make full use of Abis resources to improve
transmission utilization for the purpose of resource sharing. Moreover, this function can
be more effective to balance and guarantee transmission resource requirements by
various services on the allocation principle of service priority.
Abis timeslot resources refer to the 16Kbit/s E1 timeslots, whose static attributes describe
the access positions of Abis resources on BSC side and top-level BTS side, and whose
dynamic attributes describe the actual connection relations between allocated Abis
resources and radio timeslots.
When the dynamic Abis function is not used, the speech traffic channels need to be
mapped to the Abis timeslots fixedly according to certain connection relations. Meanwhile,
the PDCH of data service needs to be allocated and preconfigured on the Abis channel in
a half-fixed mode.
When the dynamic Abis function is in use, the Abis timeslot resources no longer need
permanent one-to-one mapping with traffic channels, and all Abis timeslot sources are
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formed as a resource pool capable of unified allocation. This resource pool uses the full
dynamic high-level share allocation algorithm based on certain service timeslot
requirement proportions to guarantee an effective balance between speech channels
with high priority and data services at various rates.
The dynamic Abis of ZTE ZXG10 iBSC has two characteristics: one is that Abis
resources are organized as a resource pool, and the other is that high-priority speech
services are involved in allocation.
A speech service is characterized by high priority and occupation of a fixed number of
Abis timeslots (16K). A packet service is characterized by low priority and occupation of a
variable number of Abis timeslots (8K, or N×16K, N ranging from 1 to 4 or 1 to 5).
A CS service has high priority, and can use all Abis resources, including those occupied
by PS services, but excluding those occupied by other CS services. To guarantee
preference of speech services and decrease frequent connection of Abis timeslots, the
upper limit of Abis timeslots occupied by PS services is set, and the Abis resources are
allocated by share.
Figure 3-1 Use of Abis resources
All Abis resources are organized by means of resource pools. One site can be configured
with more than one resource pool, and the cells under this site can use the Abis
resources under all resource pools of the sites at the equal level. In a structure with
cascaded sites, an upper level site can use the Abis resources of a lower level site. For
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example, in 0, the resource pools of BTS2 and BTS3 are P1 and P2 respectively, so the
Abis resource pools BTS1 can use are P1 and P2.
The principles of allocating a share of an Abis resource pool are as follows:
Allocation by share means to allocate required resources by share during request for
packet resources. All cells that share one resource pool are each allocated with a
percentage of share, and the shares of all cells in the pool add up to 100%. Shares are
calculated based on some statistics, and each type of statistics is associated with a
weight based on its importance. Statistics include number of cell carriers, packet access
times, quantity of packet transmission data, and EGPRS request times. Shares are
recalculated at regular intervals,the parameter is GetStaticParamTimer, which can be set
via OMC-R. Within the limit of share, two Abis timeslots are allocated to each channel of
GPRS carrier, while four Abis timeslots to each channel of EGPRS carrier.
The above description can be configured as the parameters in the parameter list
suggests.
Each time Abis timeslots are allocated, a speech service and a packet service have
different allocation scopes, as shown in Figure 3-2 below:
Figure 3-2 Abis timeslot allocation
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For PS services, OMCR configures the share of a cell in an Abis resource pool, and each
of other resource pools must comply uniformly with this share requirement. If a resource
pool is configured totally with N Abis resources (16Kbit/s), the maximum amount of Abis
resources available for PS services is: PoolAbisForPS1 = N × PSAbis (upper limit of
share).
The amount reserved for CS services is: PoolAbisForCS1 = N - PoolAbisForPS1.
When some cells share one resource pool, the statistic share of each cell, temporarily
recorded as Cell_Share1, must be considered when allocating Abis resources. This
share is calculated by the RRM process. RRM provides a query interface for DBS to
query when allocating Abis resources.
If it is known that the number of Abis timeslots for PS occupied by this cell in the resource
pool is PoolAbisUsedPS1, the quantity of Abis resources available for PS services in this
cell is:
CellAbisForPS1 = MAX (PoolAbisForPS1× Cell_Share1/100-PoolAbisUsedPS1, 0);
CellAbisForPS1 means the Abis resources owned by this cell in the resource pool and
available for PS services.
If this cell crosses n resource pools, similarly it can be figured out that the quantity of Abis
resources owned by this cell in the resource pool and available for a new PS service is
CellAbisForPSn, and the total amount of Abis resources of this cell available for PS
services is:
SumCellAbisForPS = CellAbisForPS1 + … + CellAbisForPSn
The triggering way of calculating share of Abis resources for a cell is as follows:
The configuration data information of Abis resource pools is organized and maintained in
DBS, and is changed as a result of some operations, mainly including:
Adding/deleting a PSBTS cell;
Adding/deleting TRX to/from a PSBTS cell;
Adding/deleting an Abis resource pool;
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Blocking/unblocking the DSP on UPU;
Blocking/unblocking BVC.
When Abis resource pools undergo changes, DBS will send to RRM a message about
changes and configuration update of the resource pools, and RRM will calculate the
information of the cells contained in each resource pool, and the share of Abis resources
by each cell for PS services.
The following are two examples of performance enhancement calculation.
Example 1: Suppose there is a network that can support 4-timeslot EGPRS mobile
phones, but with a low penetration rate of EGPRS data service. Then in a three-sector
site, there is low probability that more than two cells request EGPRS service
simultaneously, so what we need to do is to set a fixed 64K E-PDCH channel for each
cell to meet the E-PDCH/PDCH service request at any time. Moreover, the full dynamic
Abis function allows placement of three 64K E-PDCHs into one Abis resource pool to
enable three cells in this site to share Abis transmission resources. In addition, six 16K
Abis timeslots are set to meet the GPRS service request from each cell.
Without dynamic Abis, this site has the Abis transmission requirement (data service) as
follows:
3 cells × (4 × E-PDCH × 64Kbps) = 12 × 64Kbps
With dynamic Abis in use, this site has the Abis transmission requirement (data service)
as follows:
[3 cells × (1 × E-PDCH) + 3 × E-PDCH (resource pool)] × 64Kbps + 6 × 16Kbps = 7.5 ×
64Kbps
As is shown, when the full dynamic Abis function is enabled, the data service in this
example has obviously lower requirement for Abis transmission resources, and the saved
bandwidth amounts to a proportion of 37.5%.
Example 2: For a S4/4/4 site, suppose each cell is configured with four E-PDTCHs
(maximum code MCS-9) and two control channels:
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Without dynamic Abis, the full-service Abis transmission resource requirement is as
follows:
(26 × 16kb/s + 4 × 4 × 16kb/s) × 3 = 42 × 3 × 16kb/s = 126 × 16kb/s.
In the case that dynamic Abis is in use based on the traffic model of experiential speech
and data services, suppose that only one cell is full loaded with CS and PS services; the
second cell is configured with 75% CS services and one E-PDTCH; the third cell is
configured with 50% CS services and two E-PDTCH, then the quantity of Abis
transmission resources required is:
(26 × 16kb/s + 4 × 4 × 16kb/s) + (75% × 26 × 16kb/s + 1 × 4 × 16kb/s) + (50% × 26 ×
16kb/s + 2 × 4 × 16kb/s) = 87 × 16kb/s
Therefore, in this example, (126-87)/126 = 31% of Abis transmission resources are saved.
In practical BTS networking, the larger the number of BTSs and cells sharing Abis
resource pools, the smaller the quantity of concatenated transmission resources.
4 Parameters and Configurations
4.1 Parameter List
Table 4-1 Parameter List
Full name Resource pool for PS rate
Abbreviation PsAbisThs
Description
Full dynamic Abis resource pool provides use proportion of PS channel.
if default value for this parameter is configured as 80%, which refers to
upper limit for PS. The aim is to idle Abis resource while CS channel is
activated. If this threshold is exceeded, Abis resource can't be allocated
to PS service again.
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Management
Object Abis
Value Range 0 ~ 100
Unit %
Default 80
Full name RS
Abbreviation RS
Description Uplink throughput weight value at Gb interface, the dynamic Abis
adjustment parameter.
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 20
Full name RR
Abbreviation RR
Description Downlink throughput weight value at Gb interface,
the dynamic Abis adjustment parameter.
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 20
Full name RA
Abbreviation RA
Description Weight value of EGPRS MS accessing request
times, the dynamic Abis adjustment parameter.
Management
Object BSC
Value Range 0 ~ 100
Unit None
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Default 10
Full name RM
Abbreviation RM
Description Weight value of high-bandwidth request times, the
dynamic Abis adjustment parameter.
Management
Object
Value Range 0 ~ 100
Unit None
Default 25
Full name RB
Abbreviation RB
Description Weight value of the highest bandwidth usage, the dynamic Abis
adjustment parameter.
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 10
Full name RG
Abbreviation RG
Description This parameter defines weights of GPRS carrier proportion,
RS+RR+RA+RM+RB+RG+RE must be equal to 100.
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 5
Full name RE
Abbreviation RE
Description This parameter defines weights of EDGE carrier proportion,
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RS+RR+RA+RM+RB+RG+RE must be equal to 100
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 10
Full name C
Abbreviation C
Description This parameter defines how to trigger adjustment threshold of dynamic
resource
Management
Object BSC
Value Range 0 ~ 100
Unit None
Default 5
4.2 Parameter Configurations
In the Panel Property window of CMB, use to add desired Timeslot Number to
Abis Resource Pool, or use to release the timeslots from the Abis Resource
Pool. The related configuration interface is shown in 4-2.
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Figure 4-1 Dynamic Abis configuration interface 1
Note:
Users are allowed to configure Abis resources as needed, and can configure four
resource pools at most, and one at least.
1 In the configuration resource tree window, open OMC → GERAN Subnetwork →
BSC Managed Element → Config Set, and double-click BSC Function. In the
Other GPRS Properties 2 tab of the window on the right, set Proportion of Full
Dynamic Abis Resource Pool for PS Channels, as shown in 0-3.
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Figure 4-2 Dynamic Abis configuration interface 2
2 In the EDGE Properties tab, set the following related parameters for calculation of
the share of Abis available to each cell in the resource pool of the site:
Gb Interface Uplink Throughput Weight
Gb Interface Downlink Throughput Weight
EGPRS MS Access Request Count Weight
High Bandwidth Request Count Weight
Highest Bandwidth Usage Weight
GPRS Carrier Proportion Weight
EDGE Carrier Proportion Weight
Dynamic Resource Adjustment Trigger Threshold
The related configuration interface is shown in Figure 4-4 as follows:
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Figure 4-3 Dynamic Abis configuration interface 3
5 Related Counters and Alarms
5.1 Related Counters
None
5.2 Related Alarms
None
6 Engineering Guide
The resource pool number under a site and the Abis resource quantity under a resource
pool must be planned and set as required actually.
6.1 Application Scenario
In the case of full dynamic Abis, as described in the previous section, all Abis timeslot
resources are connected by BTS from the ingress to the egress, without any one
connected to a carrier. Therefore, a call of each telephone set needs a timeslot allocated
from a resource pool for completing its connection. Each timeslot can be allocated to any
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BTS associated with it, but can no more be allocated to any other BTS before it is
returned. What is refereed to as “return” here means BTS reconnects this timeslot from
the ingress to the egress.
In a single site, site S1 can be
connected simultaneously to Abis
resource pools a and b, each of which
can manage and allocate timeslots
dynamically for PS and CS services.
Star Networking
One E1 line connects three sites S1,
S2, and S3 in a star network. As
shown in the diagram, both resource
pools a and b are a subset of this E1
resource, so S1 can use the resources
in a and b, while S2 can use only b,
and S3 only a. The relation between
S1 and a is that S1 enters a from port
A and exits from port E, and the
relation between S1 and b is that S1
enters b from port A and exits from
port D. The relation between S2 and b
is that S2 enters b from port A and
exits nowhere, and the relation
between S3 and a is that S3 enters a
from port A and exits nowhere.
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Ring Networking
The red resource pool follows the
route of entry into A of S1 and exit
from D, entry into D of S2 and exit
from A, and then back to iBSC. By
contrast, the blue resource pool enters
A of S2 and exits from D, enters D of
S1 and exits from A, and finally loops
back to iBSC. Regarding initial data
configuration, the relation between S1
and the blue resource pool is in block
state by default. So is the relation
between S2 and the red resource
pool.
Therefore, what is referred to as ring
network switchover just means to, with
S2 as an example, block its relation
with the blue resource pool and
unblock its data relation with the red
resource pool.
6.2 Configuration Description
This function does not involve adjustment of iBSC or BTS hardware configuration.
6.3 Network Impact
When enabled, the full dynamic Abis function, in addition to increasing utilization of Abis
transmission resources, can improve the performance indexes (like data throughput) of
data services (like GPRS and E-GPRS) when the transmission resources are limited. The
full dynamic Abis function, when enabled, has no impact on the capacity that iBSC and
BTS equipment can carry themselves.
S2
S1
D
D
A
A
iBSC
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7 Abbreviation Abbreviations Full Characteristics
3GPP 3rd Generation Partnership Project
GSM Global System for Mobile communications
BSC Base Station Controller
BTS Base Transceiver Station
MS Mobile Station
MSC Mobile Switching Centre
OMC Operation & Maintenance Center
GPRS General Packet Radio Service
EGPRS Enhanced GPRS
EDGE Enhanced Date Rates for GSM Evolution
TCH Traffic Channel
PDCH Packet Date CHannel
PDTCH Packet Date Traffic CHannel
8 Reference Document
[None]