OMF007001 Frequency Planning ISSUE1.4

Frequency planning Tight frequency reuse Frequency hopping... Frequency planning Tight frequency reuse Frequency hopping... Tight Frequency Reuse TechnologyMulti-layer reuse pattern Un

OMF 007001 Frequency Planning

ISSUE1.4

OMF 007001 Frequency Planning

ISSUE1.4

Wireless Training Department

Frequency planning

Tight frequency reuse Frequency hopping

Content of Frequency planning

Frequency resource of GSM system

Requirement for interference and interference ratio

carrier-to-Signal quality grade coding

Concept of frequency reuse

4*3 frequency reuse

Frequency Band Configuration

All useful signals carrier

Useful signal Noise from environment

Requirement for Interference and

Carrier-To-Interference Ratio

Requirement for Interference and

Carrier-To-Interference Ratio

Effect of Interference

 Bit error

 Recoverable: channel coding, error correction

 Irrecoverable: phase distortion

 System interference model

 Unbalanced: uplink interference ≠ downlink interference

 Asymmetrical: the interference is different at the MS and BTS ends

RXQUAL Mean BER BER range class (%) from to

Level of receiving quality (0 7)

 Bit error rate before decoding and error correction

{fi,fj fk} {fi,fj fk} {fi,fj fk}

Macro-cell system

dMicro-cell system

Concept of Frequency Reuse

The Reason of Frequency Reuse

resource, 8 MHz = 40 channels * 8 timeslots = 320 ==> max 320 users can access the network at the same time.

Looser reuse

Higher frequency reuse

efficiency, but interference

is serious More technique

[fn]

D

[fn]

R

Reuse of a frequency causes the co-channel interference

Problem of Frequency Reuse

Interference (C/I) Estimation

D

This old-fashioned frequency distribution mode is not recommended

Frequency Reuse Patterns

 Purpose: to minimize the interference in the whole network with the final frequency allocation plan

 Theoretically

 Regular hexagon cell

 Regular network distribution

 Cell cluster

 Multiplexing distance

D = R *sqrt(3*K)

A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3

A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3

A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3 A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3 A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3

A1 C1

B1 D1

A2 A3

B2 B3

C2 C3

D2 D3

4*3 Frequency Reuse

Frequency planning

Tight frequency reuse

Frequency hopping

Tight Frequency Reuse Technology

Multi-layer reuse pattern

Underlaid and overlaid cell

1*3

1*1

Multi-layer Reuse Pattern

BCCH: n1 TCH1: n2 TCH2: n3

Multi-layer Reuse Pattern Frequency Allocation

RC type frequencies Allocated

Number of available frequencies

BCCH TCH1 TCH2 TCH3 TCH4{f1,f3,f5 f23}

{f1,f2,f3,f4,f5 f40}

{f2,f4 f22,f24 f40}

Multi-layer Reuse Pattern Frequency Allocation

Capacity increase when reuse density is multiplied:

 Supposing there are 300 cells

Capacity increases when reuse density is multiplied:

 Supposing there are 300 cells

The inner circle covers a smaller area, and the

Underlaid/Overlaid Frequency Allocation

Overlaid-cell

Underlaid-cell

Super fn Regular fm Regular fm

Regular fm Super fn

TRX1 TRX2 TRX7

TRX8 TRX9 TRX14 TRX15 TRX16 TRX21

TRX1 TRX2 TRX7

TRX8 TRX9 TRX14 TRX15 TRX16 TRX21

The red items are BCCH RCs

Illustration of 1*3 TCH Frequency Allocation

Frequency Planning Principle

There should be no co-channel frequency carriers in one BTS

The frequency separation between BCCH and TCH in the same cell should be not less than 400K

When frequency hopping is not used, the separation of TCH in the same cell should be not less than 400K

In non-1*3 reuse mode, co-channel should be avoided between the immediately neighbor BTS

Neighbor BTS should not have co-channels facing each other directly

Normally, with 1*3 reuse, the number of the hopping frequencies should be not less than twice of the number of frequency hopping TRX in the same cell

An example network in a specific place, BTS are densely located The topography is plain The maximum BTS configuration is

S3/3/2.Initial planning:

Example of Frequency Planning

Final frequency planning:

Example of Frequency Planning

Example of 1*3 Frequency Reuse

Group 1 (MA1): 110 111 112 113 114 Cell1

TCH Consecutive Allocation Scheme

TCH Interval Allocation Scheme

Group 1 (MA1): 110 113 116 119 122 Cell1 Group 2 (MA2): 111 114 117 120 123 Cell2 Group 3 (MA3): 112 115 118 121 124 Cell3

Comparison Between Multi-layer reuse and 1*3

For Multi-layer reuse pattern, either Base band hopping or RF hopping can be used But for 1x3 reuse, only RF hopping can be used

Multi-layer reuse pattern is a gradual process for TCH frequency planning In other words, the reuse is rather loose in TCH1 layer and

it is quite close in the last TCH layer (such as TCH5) The reason for this pattern is that base band hopping is used in the Multi-layer reuse pattern When there are rather few frequency carriers, the hopping gain is small Therefore, more frequency carriers should be allocated for the layer with small TCH and then the reuse coefficient is relatively large When RF hopping is used in the Multi-layer reuse pattern and there are a large number of frequency carriers, the hopping gain is high and the reuse coefficient can be very small In

Comparison Between Example of Frequency

For the cells with fixed number of TRX, when the traffic is heavy, the 1x3 provides higher service quality than that of Multi-layer reuse pattern.

of hopping should not exceed the product of the allocated hopping frequency number and the max RF load ratio

frequency hopping, while BCCH in 1x3 mode can not.

Frequency planning Tight frequency reuse

Frequency hopping

Content of Frequency Hopping

Frequency Hopping

Base Band Hopping Principle

RF Hopping Principle

Advantages of Hopping

Tighter reuse patterns are possible to be used for larger capacity.

Frequency Diversity of Hopping

Smoothen and average the interference

Interference Diversity of Hopping

Description Hopping Parameters

element in MA set MAI is used for indication, referring to a specific element in the MA set

When 0< MAI<n-1

MAI is the function of TDMA FN, HSN and MAIO.

Description Hopping Parameters

At the air interface, the RC number on a specific burst is an element in MA set MAI is used for indication, referring to a specific element in the MA set

When 0< MAI<n-1

MAI is the function of TDMA FN, HSN and MAIO.

Description of Hopping Parameters

onds a pseudo random sequence.

Hopping Parameters

three options: not hopping, base band hopping and RF hopping.

 Location: in 【 Cell Configuration Table 】

CA (Cell Allocation Table): refer to all available frequency carriers in the cell The allocation should be consecutive starting from the effective frequency carrier 0 There should be

no empty data item The frequency carrier configuration should

be in an ascending order.

 Location: in 【 Cell Allocation Table 】

Hopping Parameters

when hopping, containing at most 16 frequency carriers The frequency being used must be those of the corresponding cell

BCCH channel should be in the set.

 Location: in 【 Carrier Configuration Table 】

for hopping 0 stands for sequence hopping and other values for pseudo random sequence hopping.

 Location: in 【 frequency hopping table 】

TSC (Training Sequence Code): used for delay equalization at the receiver end TSC must be the same as the BTS color code When

an MS or BTS receives signals, delay equalization is started with the specified TSC But for the co-channel signals with different TSC, delay equalization is impossible, so that demodulation can not be received In this way, erroneous receiving is prevented effectively and then co-channel interference is prevented

Note: “√” means absolutely same; “×” means absolutely different;

Hopping Data Configuration Rules

Description of Cell Allocation Table

Field Name Meaning Value range Suggestion

containing the cell

0~255

HW-IUO

property

Indicating whether TRX should be configured

as OverLaid or UnderLaid subcell

equipment

group ID

The number of the equipment group at the site One site supports at most 3 equipment groups; It is usually configured as “0” at present

The subset

of the effective RC

Static transmitting power level of the RC “0”

corresponds to the static power 46dBm, i.e

40W The static power is lowered by 2dB with the level goes up by 1

actual condition and the

Description of RC Configuration Table

The index number of all sorts of hopping

Channel Configuration Table】 The numbers are in a sequence starting from 0

0~255

HSN

HSN, indicating the sequence rule of the hopping Usually, there is only one HSN in the same cell and the HSN in the co-channel cell must be different The above-mentioned

rules must be observed

0~63

TSC

Decide the parameters of the self-adaptive equalization filter in the receiving processing filter It is the same as the corresponding

base color code (BCC)

0~7

FH

ARFCN

Number of frequency in the hopping serial

According to hopping algorithm, at least 3 frequencies are required for hopping gain If this field is left blank, it is invalid

Corresponding participant hopping

ry

Description of Hopping Data Table

Domain name Meaning Value range Suggesti

on

“TCH Full Rate”, “TCH Half Rate 01”, “TCH Half Rate 0”, “SDCCH8”, “Master BCCH”,

“Composite BCCH”, “BCH”, “BCCH + CBCH”,

“SDCCH + CBCH”, etc

9 channel groupings

FH index

number

It is used to index to corresponding record in

of hopping frequency

Description of Radio Channel Configuration Table