zgo-03!03!001 full dynamic abis allocation fg 20101030

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ZGO-03-03-001 Full Dynamic Abis Allocation

Feature Guide


ZTE Confidential Proprietary © 2010 ZTE CORPORATION. All rights reserved. I


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.


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


ZTE Confidential Proprietary © 2010 ZTE CORPORATION. All rights reserved. III

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



TABLES

Table 4-1 Parameter List .................................................................................................. 7


ZTE Confidential Proprietary © 2010 ZTE CORPORATION. All rights reserved. 1

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



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



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



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



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;



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:



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.



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



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,



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.



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.




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:




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



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.



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



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]

zgo-03!03!001 full dynamic abis allocation fg 20101030

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