concentric cells in GSm

(1)

Concentric-Dual Band

Cells



_Introduction



Definition



Why Dual Band Cells?



Propagation Overview



Fading Effect



Path loss and Link Budget Calculations

(2)

Introduction

Definition

• Enables a single Network

Operator with licenses in two or

more frequency bands to support

the use of Multiband mobiles in

all bands of the licenses

• The use of Layers to provide high

capacity

with

contiguous

coverage.

The

Outer

Zone

maintains contiguous coverage

and the Inner Zone provides

higher

capacity.

The

layers

appear as being concentric due

to Inner Zone having a reduced

coverage area when compared

with the Outer Zone.

(3)

Prepared By - Faraz Husain Concentric - Dual Band Cells

Definition (cont.)



The idea is to split the cell area of a

normal cell into an inner and an outer

zone by operating a certain number of

carriers (inner zone carriers) at a lower

transmission power (Fig). Mobile

stations situated in the outer zone

communicate on the outer carriers.

The mobiles which are closer to the

base station preferably communicate

on the inner carriers but they can use

the outer carriers if needed.



With this feature the operator may configure non-BCCH carriers within a cell to have

a smaller coverage area. The carriers equipped within a cell may be grouped into two

zones:

• Zone 0: Also referred to as the "outer zone", is reserved for carriers that may broadcast

at the maximum transmit level defined for the cell.

• Zone 1: Also referred to as the "inner zone", may be defined with non-BCCH carriers

transmitting lower power than the BCCH carrier, or having a tighter reuse pattern that reduces the useful coverage area of the carrier.

(4)

Definition (Cont.)



Concentric Cells can be implemented using one of the three

different algorithms (this is vendor dependent):



Power Based Concentric Cells

:

Inner zone carriers transmit less power than

outer ones and the transitions between zones are based on absolute level thresholds.



Interference Based Concentric Cells:

Inner and outer zone carriers transmit

all the same power within and the transitions between zones are based on some interference

conditions. These interference conditions are protection margins against potential interfering

neighbours.



Dual Band Cells:

Support for the management of the cells operating in different bands

by different single band BTS’s or by the same dual band BTS. This is further divided into two

kinds



Coincident Multiband



Single BCCH for Dual Band cells

Since we’re using Dual Band Concentric Cells in our network, we’ll

be concentrating more on them for the rest of the workshop!

(5)

Why Dual Band Cells?



Increasing Capacity



Improving Grade of Service



Relieving Congestion



Advanced Network Management Techniques



Efficient management of traffic required to exploit capacity gain

potential of concentric cells



Goals



Maximize handled capacity



Avoid congestion



Maintain good call quality



Avoid unnecessary handovers



Improved Multi-layer Network



Best system performance through optimal choice over



Call originations



Traffic movement between concentric cell layers



Generalized handover situations

(6)

(7)

Propagation Overview

Fading Effect

Serving

Site

Distant

Site

Higher pathloss at

1800 MHz

Half wavelength

l

at 1800 MHz

Fading rate twice as fast as 900MHz

1800 radio wave

•Reduced interference from

distant site at 1800MHz

•More aggressive reuse pattern

can be achieved

•Diversity systems become more

important especially for slow

moving mobiles

(8)

Propagation Overview

Fading Effect

The wavelength of a radio signal

determines many of its propagation

characteristics

• Antenna elements size are typically in the

order of 1/4 to ½ wavelength

• Objects bigger than a wavelength can reflect

or obstruct RF energy

• RF energy can penetrate into a building or

vehicle if they have apertures a wavelength in

size, or larger

(9)

Propagation Overview

Antennas

Different Antenna Types

• Different antenna for each Band

• Dual antennas with four ports

• Dual Antennas with 2 ports (900

and 1800 are multiplexed )

(10)

•Extra Duplexers will be

needed to split 1800 signal from 900 signal

•Duplexers will be with

different polarization to maintain diversity

(11)

Propagation Overview (cont.)

Path Losses in 900 vs. 1800

• A little physics

– Diffraction loss and Penetration loss higher in 1800 MHz band

– 6dB minimal theoretical difference

• Path loss difference - on-street

– Path loss at 1800MHz is typically 6 - 12 dB higher

– Most probable difference in urban environment: 8 dB

– Difference is nearly distance-independent (fixed), in typical urban cells (

i.e. constant offset in “ loss per length unit ” )

– Actual difference depends on site configuration like antenna height and

antenna characteristics

(12)

Propagation Overview (cont.)

Path Losses in 900 vs. 1800

• Path loss difference - in-building

– Additional attenuation at 1800MHz when penetrating into buildings

– High dependency of penetration loss on building structure, window size,

floor height, angle of incident waves and floor level

– Difference can be compensated with a higher ERP at the 1800 band

• Empirical measurement results

– Building penetration loss at 900MHz:

5dB to 25dB

– Average additional path loss at 1800MHz:

7dB, 4dB standard deviation

(13)

Propagation Overview (cont.)

Path Losses in 900 vs. 1800

Re

ce

iv

e

lev

el

(dB)

Log (Distance)

LOS dominates

Non-LOS dominates

~ 150m - 300m

GSM 900

GSM 1800

>8 dB

6 - 8 dB

in typical urban cells:

• difference is nearly distance-independent

prerequisite:

• same ERP on both bands

• equal antenna pattern

(14)

Propagation Overview (cont.)

Path Losses in 900 vs. 1800

Optimisation process:

• Comparing predictions of appropriate GSM900 and GSM1800 cells for

in-building coverage level

(e.g. -68 dBm at 900Mhz / -61 dBm at 1800MHz)

• Adjusting GSM1800 antenna tilts to obtain similar footprint compared to

the appropriate GSM900 cell

– Good overlapping needed to achieve efficient traffic relief on GSM900

– Supports introduction of new multi-band features like coincident multi-band

handover or single BCCH

• Same coverage conditions (except fairly fixed offset) can be achieved

easily with dual band antennas

• Reducing Combining stages in the DCS cells to reduce the losses and use

air combining instead.

(15)

Propagation Overview (cont.)

Link Budget & Path Loss

(16)

Propagation Overview (cont.)

(17)

After having studied in detail the propagation

difference between GSM 900 and DCS 1800,

let us switch back to our original discussion of

Implementing the DCS in a Live network.

Lets look at some BSC and Cell Level

Parameters and then we’ll move forward to

(18)

Database Parameters

BSC Level Parameters



freq_types_allowed



mb_preference



early_classmark_sending



early_classmark_delay



phase2_classmark_allowed

MOTOROLA

---

ALCATEL



EN_INTERBAND_NEIGH



PREFERRED_BAND



GSM_PHASE



EN_SEND_CM3



EN_LOAD_OUTER

MSC:

Ensure phase2 signalling is enabled between BSCs and/or MSCs

(Phase 1 = Legacy MS, Phase 2 introduced around 1999 supporting features like

AMR and DCS)

(19)

Database Parameters

(cont)

BSC Level Parameters –

Description



freq_types_allowed

Numeric value Text string

1 pgsm

2 egsm

3 pgsm,egsm

4 dcs1800

5 pgsm, dcs1800

6 egsm, dcs1800

7 pgsm, egsm, dcs1800

8 pcs1900

9 pgsm, pcs1900

10 egsm, pcs1900

11 pgsm, egsm, pcs1900

12 dcs1800, pcs1900

13 pgsm, dcs1800, pcs1900

14 egsm, dcs1800, pcs1900

15 pgsm, egsm, dcs1800,

pcs1900

MOTOROLA



mb_preference



The mb_preference parameter enables

or disables the Multiband Inter-cell

Handover feature.

Valid Range

 0 = Disabled  1 = Enabled

(20)

Database Parameters

(cont)

BSC Level Parameters –

Description



To have a working Dual-Band capability, the MSC needs to have the capability to handle

Classmark 3 IE (info element)



CM3 info is sent by multiband MS and contains info about multiband capabilities and power

classes of the mobile in different bands



This info is present in the MSC for the duration of the call



In case a multiband handover needs to take place, the serving BSC needs to transmit this info to

the target BSC to inform the target BSS of the capabilities of the MS



CM3 is important message but is only sent by the MS when requested by the MSC



However, it is possible to send an early CM3 spontaneously using some BSS level parameters.



This will enable a multiband MS to spontaneously send CM3 info within some specific

time during Call initializing procedure and ALSO enables the MSs to handover a call to

target BSC (external Handover) by sending CM3 info in Handover Request Message

(21)

(22)

(23)

(24)

Database Parameters

(cont)

BSC Level Parameters –

Description

MOTOROLA

 early_classmark_sending

The early_classmark_sending parameter specifies the following:

• Whether the BSS suppresses the early sending of the Classmark Update message to the MSC. • Whether an MS is allowed to send an early Classmark Change message.

Valid Range

0 = Disabled across both the A-interface and the Air-interface 1 = Enabled on A-interface, disabled on Air-interface

2 = Disabled on A-interface, enabled on Air-interface

3 = Enabled across both the A-interface and the Air-interface

By Air Interface, Motorola means CM3 sending during Call Setup and by A-Interface, it means CM3 sending during External Handover

When early_classmark_sending is set to 2, the BSS does not forward classmark update messages to the MSC. This means that the MSC does not obtain any information about the MS capabilities. However, the MSC can still make solicited requests for classmark updates by sending a Classmark Request message to the BSS. If this is not done, the frequency capabilities of the MS are based on the target cell frequency when multiband handovers are being performed. Therefore, after an external handover, neighbours are reported by the BSS to the MS as follows:

Handover from GSM900 to GSM900 - only the GSM900 neighbours Handover from GSM900 to GSM1800 - only the GSM1800 neighbours Handover from GSM1800 to GSM900 - only the GSM900 neighbours

(25)

Database Parameters

(cont)

BSC Level Parameters –

Description



early_classmark_delay

The early_classmark_delay timer specifies how long the BSS delays sending the Classmark Update message to the MSC during Early Classmark sending.

 Valid Range

0 to 100000 milliseconds



phase2_classmark_allowed

The phase2_classmark_allowed parameter defines the format of the classmark parameter sent to the MSC based on GSM phases.

 Valid Range

0 = Formatted for Phase 1 1 = Formatted for Phase 2

2 = Formatted for Phase 2 with Multiband

(26)

Database Parameters

(cont)

BSC Level Parameters –

Description



EN_INTERBAND_NEIGH (

EN_INTERBAND_HO

)

This flag enables / disables the multiband operation by filtering the sending of SYSTEM INFORMATION TYPE 2ter/5ter.



PREFERRED_BAND

Frequency band to which the multiband MS are preferentially directed.

Valid Range 0 = None 1 = GSM 2 = DCS



GSM_PHASE

This flag indicates the GSM Phase used by the BSC to format messages towards the MSC.

Valid Range

0 = GSM Phase 1 1 = GSM Phase 2

(27)



EN_SEND_CM3

This flag enables/disables sending of "Classmark 3" IE to the MSC.

 Valid Range 0 = Disabled 1 = Enabled

ALCATEL

Database Parameters

(cont)

(28)

Database Parameters

(cont)

BSC Level Parameters –

Description



EN_LOAD_OUTER

(Load computation in outer zone)

 Flag to enable/disable the load computation on the outer zone of a Concentric/multiband cell instead of the load

computation on the whole cell.

Valid Range

0 = Disabled 1 = Enabled

 When enabled, the values of the parameters FREElevel_1 to FREElevel_4 need to be updated to number of TRX

considered in the load computation. EN_LOAD_BALANCE & EN_LOAD_OUTER should not be both "Enabled".

(29)



Lets take a break. I’d advise we all take

some deep breaths….How about a

joke?!?!??!

(30)

Lets head back to the Workshop!

Now we’ll discuss the Cell Level Parameters

that are most commonly used in relation to

(31)

Database Parameters

(cont)

Cell Level Parameters

 frequency_type  interband_ho_allowed  Inner_zone_alg Thresholds:  Rxlev_dl_zone  Rxlev_ul_zone  Zone_ho_hyst  Dual_band_offset  Secondary_freq_type Optional:  band_preference  band_preference_mode  multiband_reporting  Ms_txpwr_max_inner  Bts_txpwr_max_inner  Ho_pwr_level_inner  Outer_zone_usage_level  Pbgt_mode  sdcch_tch_assign_delay

MOTOROLA

---

ALCATEL

•EN_BETTER_ZONE_HO •CELL_TYPE •FREQUENCY_RANGE •EN_MULTIBAND_PBGT_HO •EN_Bi-BAND_MS Thresholds: •RXLEV_DL_ZONE •RXLEV_UL_ZONE •ZONE_HO_HYST_UL •ZONE_HO_HYST_DL •Ping_pong_Margin •Optional: •EN_PREFERRED_BAND_HO •PREFERRED_BAND •EN_BETTER_ZONE_HO •BS_TXPWR_MAX_INNER •MS_TXPWR_MAX_INNER •MULTIBAND_REPORTING

(32)

Let us first discuss the parameters that

ENABLE the Dual-Band capability in both

vendors. Then we’ll discuss one by one the

Call Assignment and Inter-Zone

Handovers in Motorola and Alcatel

(33)

Database Parameters

(cont)

Cell Level Parameters --

MOTOROLA



frequency_type

The frequency_type parameter specifies the frequency type of a cell.

Valid Range

1 = PGSM

2 = EGSM

3 = DCS 1800

4 = PCS 1900

BEWARE!!!!

intra_cell_handover_allowed

This database parameter you’ll see every now and once which you’ll confuse with enabling of Inter Zone Handovers. This parameter has nothing to do with Inter Zone handovers. However, if a Zone attempt to Inner Zone fails due to some reason and you really need to make a handover, you cant initiate an emergency (Quality, Interference) Handover if intra_cell_handover_allwd is disabled

(34)

Database Parameters

(cont)

Cell Level Parameters --

MOTOROLA



interband_ho_allowed

Changes or sets the allowable frequencies which a cell may handover to.

This parameter must include, at a minimum, the frequency type for the cell. For example, if the cell has a

frequency_type of pgsm, then the interband_ho_allowed parameter must include pgsm as a possible

destination frequency band for handovers

Valid Range : 1 to 11

1 = PGSM 2 = EGSM 3 = PGSM and EGSM 4 = DCS1800 5 = PGSM and DCS1800 6 = EGSM and DCS1800 7 = PGSM, EGSM and DCS1800 8 = PCS1900 9 = PGSM and PCS1900 10 = EGSM and PCS1900 11 = PGSM, EGSM and PCS1900

(35)

Database Parameters

(cont)

Cell Level Parameters --

MOTOROLA



Inner_zone_alg

The inner_zone_alg parameter specifies the use algorithm and the associated parameters for the inner zone of the cell.

Valid Range

0 = Disable inner zone

1 = Power based use algorithm.

The system displays prompts for:

 ms_txpwr_max_inner  Zone_ho_hyst

 Rxlev_ul_zone  Rxlev_dl_zone

2 = Interference based use algorithm.

The system prompts for:

 neighbor_report_timer 3 = Dual Band Cell use

The system prompts for:

 Secondary_freq_type  Bts_txpwr_max_inner  ms_txpwr_max_inner  Ho_pwr_level_inner  Zone_ho_hyst  Rxlev_ul_zone  Rxlev_dl_zone  Dual_band_offset

(36)

Database Parameters

(cont)

Cell Level Parameters --

MOTOROLA



Every MS reports 6 best neighbors in measurement reports when in dedicated mode.



However, in a multiband environment, to ensure that each band gets its share of MS selecting the

target band’s cell, it is possible that we reserve some positions of neighbors in the measurement

report for a particular band



This is done using the parameter

multiband_reporting

Valid Range:

0 = Normal reporting of 6 strongest neighbors

1 = Report One strongest neighbour cell, in each of the frequency bands in the neighbour cell list, excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting Cells in the band of the serving Cell.

2 = Report the two strongest cells, in each of the frequency bands in the neighbour cell list,

excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting Cells in the band of the serving Cell

3 = Report the three strongest cell, in each of the frequency bands in the neighbour cell list,

excluding the frequency band of the serving cell. The remaining positions in the measurement report shall be used for reporting Cells in the band of the serving Cell

(37)

Database Parameters

(cont)

Cell Level Parameters --

ALCATEL

 CELL_TYPE

Combination of CELL_DIMENSION_TYPE, CELL_LAYER_TYPE, CELL_PARTITION_TYPE, CELL_RANGE. Used for cell default parameter template.

Valid values

CELL_DIMENSION_TYPE Single (0), Concentric (1)

CELL_LAYER_TYPE Umbrella (2), Micro (3), Umbrella, Concentric (4), Mini (5)

CELL_PARTITION_TYPE Mini Concentric (8), Micro Concentric (9), Indoor (10), Indoor, Concentric(11)

CELL_RANGE Extended Inner (6), Extended Outer (7)

 EN_BETTER_ZONE_HO

This flag enables/disables the detection of "too high level in outer zone" handover cause (cause 13).

Valid Range 0 = Disabled 1 = Enabled

(38)

Database Parameters

(cont)

Cell Level Parameters --

ALCATEL

 FREQUENCY_RANGE

This parameter indicates the frequency range of the cell.

Valid Range: Coded over 8 bits

0: PGSM (GSM 900), 1: DCS 1800, 2: EGSM, 3: DCS 1900, 4: PGSM-DCS1800, 5: EGSM-DCS1800, 6: GSM 850, 7..255: for future use. The parameter shall be coded over 8 bits as a provision for future frequency bands support.

(39)

Database Parameters

(cont)

Cell Level Parameters --

ALCATEL

 EN_MULTIBAND_PBGT_HO

This flag enables/disables the power budget handovers Cause 12 and the traffic handovers Cause 23 between cells belonging to different frequency bands.

 EN_Bi-BAND_MS

This flag enables/disables the incoming handovers of bi-band MSs from the preferred band

(40)

Database Parameters

(cont)

Cell Level Parameters --

ALCATEL

EN_PREFERRED_BAND_HO:

This flag enables/disables the detection of handover cause 21 (high level in neighbour cell in the preferred band).

HO Cause 21 : high level in neighbour cell in the preferred band

Traffic load is taken into account for serving and target cell. Mostly used in parallel to capturing towards preferred band and discussion would be OOS (here S=Scope) of this workshop.

(41)

Concentric Cells – Implementation

After listing all the relevant parameters for Concentric cells, lets

switch our discussion to Channel Allocation Rules for



TCH Assignment



Handovers

It should be clear to you that TCH Assignments to DCS or Inner zone are always

made using the same thresholds as used for Inter-Zone (IntraCell) Handovers.

Think of TCH assignment to Inner zone as a sort of Directed Retry to Inner

Zone. We all know about Directed Retry now…don’t we? :P

(42)

Concentric Cells

Database Parameters

TCH Assignment

---

Motorola

 The BSS always selects an outer zone channel for an Immediate Assignment. If there are no resources available

in the outer zone, the BSS sends an Immediate Assignment Reject. (WE Cannot AVOID SD Blocking!)

 In order to decide to assign the call to Outer zone or Inner Zone, following parameters are checked:  Band_preference

 Band_preference_mode  Inner_zone_alg

 If band_preference = DCS and band_preference_mode is programmed so that SD to TCH assignment is towards

Inner Zone, the decision is taken by the same algorithms used for Outer to Inner Zone Handovers.

 outer_zone usage_level: allows the operator to specify the level of traffic channel congestion which must be

reached in the outer zone prior to the use of the inner zone resources. If the operator chooses to use inner zone resources whenever a MS is qualified, regardless of outer usage, the database parameter

outer_zone_usage_level can be set to 0.

(43)

Concentric Cells

Database Parameters

TCH Assignment

---

Motorola

 Band_preference: In Motorola BSS, after having set interband_ho_allowed = 1, it may be useful to utilize our

DCS resources once the immediate assignment is completed. A preference for a particular BAND is set by the parameter band_preference. parameter displays the frequency bands that the cell prefers to use for handovers and specifies the destination frequency band for inter-cell handovers.

Valid range 1 (PGSM), 2 (EGSM), 4 (DCS1800), 8 (PCS1900) 16 (GSM850)

 Band_preference_mode: parameter specifies the method the system uses to program a Multiband MS with the

preferred frequency band for a given cell in the BSS. This parameter plays role for both Inner Zone Assignment of the calls (From SD to TCH) and the Handover of the call to Inner zone.

(44)

Concentric Cells

Database Parameters

TCH Assignment

---

Motorola

VALID Ranges:

Band_preference_mode = 0

 The BSS attempts to hand a Multiband MS over to the strongest neighbour that the MS reported when a handover is required for normal radio resource reasons.

 Attempt handover to strongest preferred band neighbour on SDCCH - TCH assignment

 This is where SD_TCH_ASSIG_BAND_DELAY is used just in case one wants a delay before Preferred band neighbors are reported for Inner Zone Assignments

 If unable to handover to preferred band TCH, cancel band preference bias for the lifetime of the current connection

 Multiband handovers due to normal radio reasons may still occur

 The algorithm used for Assignment to Inner Zone is actually the one used for Handover to Inner Zone (will be discussed later in the Handover part)

 Do not invoke band changes on SDCCH - TCH assignment

 Go to strongest preferred band neighbour when normal radio reason (or congestion relief) handover required  Preferred band neighbours take priority in the neighbour list

(45)

Concentric Cells

Database Parameters

TCH Assignment

---

Motorola

 This value combines the functions of values 1 and 2.

• This would mean to prioritise preferred band at SDCCH-TCH assignment AND when radio reason handovers are required

 Do not invoke band changes on SDCCH - TCH assignment

 As soon as possible after TCH assignment, attempt to handover to a preferred band channel  For normal radio reason handover, also prioritise preferred band neighbours

 This value combines the functions of values 1, 2, and 4.

 Attempt to hand to preferred band at SDCCH - TCH assignment

 As soon as possible after TCH assignment, attempt to handover to a preferred band channel  For normal radio reason handover, also prioritise preferred band neighbours

(46)

Concentric Cells

Database Parameters

(47)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola

The inner zone use algorithm must adjust for values being from two different frequency bands and convert the

primary band receive levels to an estimated value for the secondary band. This is done using the dual band offset parameter.

RXLEVINNER = RXLEVOUTER + dual_band_offset

This offset is applied to both uplink and downlink receive levels

The calculated receive level inner value is then used in the dual band inner zone algorithm for both uplink and downlink

RXLEV_DLINNER > rxlev_dl_zone + zone_ho_hyst + (bts_txpwr - bts_txpwr_max_inner)

RXLEV_ULINNER > rxlev_ul_zone + zone_ho_hyst + (ms_txpwr - min(ms_txpwr_max_inner,P)

Within this algorithm are database parameters that are set per cell after the

inner_zone_alg = 3 (dual band use)

rxlev_dl/ul_zone = <*> *= Range 0 to 63

zone_ho_hysteresis = <*> *= Range as defined for max_tx_bts (0 to 21) bts_txpwr_max_inner = <*> *= Range -63 to 63

ms_txpwr_max_inner = <*> *= Range as defined for max_tx_ms (5 to 39 PGSM and

EGSM 0 to 36 DCS 1800)

(48)

Concentric Cells

Database Parameters

TCH Assignment

---

Alcatel

 All SDCCH channels are in the outer zone.

 The BSC can allocate a TCH in the inner zone or in the outer zone.

 Cause 13 is checked to determine the MS location (Outer to Inner Zone Handover)

Zone Assignment:

 The 900 SDCCH is always allocated to the MS (SDCCH channels are on the 900 TRX).

 Then according to the MS location (outer zone or inner zone), a TCH is allocated in the 900 band (outer zone) or in

the 1800 band (inner zone).

 To determine the location of the mobile, cause 13 (outer zone to inner zone HO) is checked.

 If the cell is congested, it is possible to allocate the TCH in a neighboring cell (Directed Retry or Forced Directed

Retry).

 Then, according to the location of the mobile, the value of the parameter EN_BETTER_ZONE_HO, the serving

BSC of the serving and the neighboring cells the TCH is allocated in :  The 900 band if the two cells belong to two different BSC,

 the 900 band if the two cells belong to the same BSC and EN_BETTER_ZONE_HO =disable for the neighboring cell  The 900 band if the two cells belong to the same BSC,EN_BETTER_ZONE_HO = enable for the neighboring cell and the

MS is located in the outer zone of the neighboring cell,

 The 1800 band if the two cells belong to the same BSC, EN_BETTER_ZONE_HO = enable for the neighboring cell and

(49)

Concentric Cells

Database Parameters

TCH Assignment

---

Alcatel



Cause 13

(too high level on UL/DL in outer zone)

 Better condition Intra-cell Handover

(50)

Concentric Cells

Database Parameters

TCH Assignment

---

Alcatel



Cause 13

(too high level on UL/DL in outer zone)



RXLEV_UL_ZONE:

Uplink level threshold for inner to outer zone handover.

Valid Range:

0 to 63 (0 = -110dBm, 63 = -47dBm)



RXLEV_DL_ZONE:

Downlink level threshold for inner to outer zone handover.

Valid Range:

(51)

Concentric Cells

Database Parameters

TCH Assignment

---

Alcatel



ZONE_HO_HYST_UL

UL static hysteresis for interzone HO from outer to inner – In case of multi-band cell, should take into

account the difference of propagation between GSM and DCS (difference in Propagation between

two bands is countered in Motorola by dual_band_offset)

Valid Range

-40 to 40 dB



ZONE_HO_HYST_DL

DL static hysteresis for interzone HO from outer to inner – In case of multi-band cell, should take into

account the difference of propagation between GSM and DCS and the difference of BTS

transmission power in the two bands

Valid Range

-40 to 40 dB

(52)

Concentric Cells

Database Parameters

TCH Assignment

---

Alcatel



PING_PONG_MARGIN(0,call_ref)

Its a penalty put on cause 13 if :



The immediately precedent zone on which the call has been is the inner zone of the serving cell

and less than T_HCP seconds have elapsed since the last handover. In this case

PING_PONG_MARGIN(0,call_ref) = PING_PONG_HCP.



If the call was not precedently on the serving cell’s inner zone (case of intercell or intrazone

handover), or if the timer T_HCP has expired, then PING_PONG_MARGIN(0,call_ref) = 0

PING_PONG_HCP

Valid Range:

0 to 127 dB



T_HCP

Time during which PING_PONG_HCP is applied after handover.

Valid Range:

(53)

Concentric Cells

Database Parameters

HANDOVERS

(54)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola

During add_cell command, when inner_zone_alg = 3 (dual band), a series of parameters are given

as inputs which will now follow along with their descriptions

 Secondary_freq_type:

If for example, frequency_type= DCS1800, the secondary_freq_type has to be any of the other types.

Valid range 1 (PGSM), 2 (EGSM), 4 (DCS1800), 8 (PCS1900) DUAL_BAND_OFFSET:

The inner_zone_alg has to consider other factors in order to handover multiband MSs between different frequency bands. The factors are:

 Due to different level of combining the loss of power between the radio unit and the top of the antenna may not

be consistent across all radio units within the cell. The power difference is calculated by subtracting the secondary band power loss from the primary band power loss.

 Due to the radio frequency propagation being weaker at 1800 MHz than at 900 MHz, propagation loss over the air

(55)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola

The inner zone use algorithm must adjust for values being from two different frequency bands and convert the

primary band receive levels to an estimated value for the secondary band. This is done using the dual band offset parameter.

RXLEVINNER = RXLEVOUTER + dual_band_offset

This offset is applied to both uplink and downlink receive levels

The calculated receive level inner value is then used in the dual band inner zone algorithm for both uplink and downlink

RXLEV_DLINNER > rxlev_dl_zone + zone_ho_hyst + (bts_txpwr - bts_txpwr_max_inner)

RXLEV_ULINNER > rxlev_ul_zone + zone_ho_hyst + (ms_txpwr - min(ms_txpwr_max_inner,P)

Within this algorithm are database parameters that are set per cell after the

inner_zone_alg = 3 (dual band use)

rxlev_dl/ul_zone = <*> *= Range 0 to 63

zone_ho_hysteresis = <*> *= Range as defined for max_tx_bts (0 to 21) bts_txpwr_max_inner = <*> *= Range -63 to 63

ms_txpwr_max_inner = <*> *= Range as defined for max_tx_ms (5 to 39 PGSM and

EGSM 0 to 36 DCS 1800)

(56)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola



rxlev_dl_zone

parameter specifies the downlink receive level threshold that must be crossed

for a handover to take place between the outer zone and the inner zone.

Valid Range:

0 to 63 (0 = -110 dBm)



rxlev_ul_zone

parameter specifies the uplink receive level threshold that must be crossed for

a handover to take place between the outer zone and the inner zone.

Valid Range:

0 to 63 (0 = -110 dBm)



Zone_ho_hyst

parameter specifies the margin for the inner zone handover hysteresis.

Valid Range: -63 to 63



Bts_txpwr_max_inner

parameter specifies the maximum transmit power BTS inner zone for

Dual Band cells.

Valid range -1 to 21 for PGSM, EGSM, and DCS1800. 1 step = 2dBm -1 = 44 dBm, 0 = 42dBm, 21 = 0 dBm



Ms_txpwr_max_inner

parameter specifies the maximum power an MS can use in the inner

zone of a concentric cell.

Valid range: Depends on the system:

5 to 39 dBm (odd values only) PGSM/EGSM 0 to 30 dBm (even values only) DCS1800

(57)

(58)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola

Dual Band Inner Zone Use Algorithms

The algos below show what conditions must exist in order to handover a call from Inner

to Outer Zone



BTS Power Control on

rxlev_dl < rxlev_dl_zone and bts_txpwr = bts_txpwr_max_inner

Or if Power Control is off

rxlev_dl < rxlev_dl_zone



MS Power Control

rxlev_ul < rxlev_ul_zone & ms_txpwr = min(ms_txpwr_max_inner,P)

Or if MS_PC is off

rxlev_ul < rxlev_ul_zone

 pbgt(n) > ho_margin if neighbour qualifies inter-cell handover  If no neighbour qualifies handover MS to outer zone

(59)

Concentric Cells

Database Parameters

HANDOVERS

& PC

---

Motorola



A network where Power Control is enabled, the power budget equation determines

the need for an inter-cell handover by essentially comparing the serving cell BCCH

signal strength to the neighbour cell BCCH signal strength.



This means the signal strength in a dual band cell must come from the primary zone.



When the call is in the secondary zone, the signal strength reported by the mobile

cannot be used in the power budget equation, because

 frequencies in the secondary band have a different propagation than frequencies in the primary

band.

 In a Power Control enabled network, the serving cell will always have the signal strength

between the PC window whereas the neighbour would report a much better level of its BCCH (Full Power)

(60)

Concentric Cells

Database Parameters

HANDOVERS

---

Motorola

Pbgt_mode



If

pdgt_mode = 0

If the mobile is assigned to a resource on the secondary band, the mobile will use the

serving channel measurements and then subtract the dual_band_offset. This estimated

value is then inserted into the power budget equation.



If the

pbgt_mode = 1

The serving cell BCCH is included in the ba_sacch neighbour cell list of the serving cell.

The mobile will then report the serving cell signal strength for the primary band, which can

be used in the calculation of power budget for neighbours with the same frequency band.

The actual number of neighbour frequencies that can be reported on is reduced by one,

also the number of true neighbours that the MS can report on is reduced from six to five. If

pbgt_mode = 1 then the server is auto equipped as a neighbour.

To solve this problem, we have been provided with a smart

parameter by Motorola!

(61)

Concentric Cells

Database Parameters

HANDOVERS

---

Alcatel



Cause 10, 11: UL or DL level too low in the inner zone



Emergency HO



Intracell handovers from inner to outer zone

• cause 10: too low level on the uplink in inner zone • cause 11: too low level on the downlink in inner zone