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WLL OVERVIEW

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INTRODUCTION

WLL stands for Wireless in Local Loop.

WLL is a Mobile Communication System.

IT is a CDMA (Code Division Multiple AccessSystem) based system.

Initially, it was employed as a part of basic

Telephony. At present full fledged Systems are available.

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SOME OF WLL SYSTEMS

CDMA based WLL Systems were originally

developed by M/s Qualcomm Inc., USA.

At present many WLL products are available

from Chinese and South Korean companies.

Some of the popular WLL Systems are from-

-L G Systems, Hyundai, Samsung-ZTE

-Ericsson, Motorola

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A TYPICAL LG WLL SYSTEM

Sub-Units of a Typical LS WLL System are-

-BSC (Base Station Controller)

-BTS (Base Trans-Receiver Station)-BSM (Base Station Manager)

-MS (Mobile Set)

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LG WLL SYSTEM

BSC

PSTN

BTS

BSM

MS

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BSC

Most important Sub-unit of a WLL System.

It works as an independent Switch.

BSC does call processing, Call management.

It is connected to PSTN (Public Switched

Telephone Network) by means of E1 link.

BSC works as an Interface between PSTN &

BTSs.

IT controls a no. of BTSs.

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BTS

A BTS serves a Cell or number of users in a Cell.

It is an Interface between BSC and the MSs.

It is connected to BSC with E1 Link and it hasRadio link with MSs.

It takes part in call processing with the BSC.

BTS controls power level of the MSs. It manages wireless resources.

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BSM

BSM is the MMC (Man Machine Communication)

device of WLL System.

It is basically a Sun Micro-System Workstation.

BSM is connected to BSC through a RS-422 link.

BSM uses Solarix as OS, Informix as DBMS, Sparc

C as Language and Motif as GUI.

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MS

MS may of two types-

-FWT (Fixed Wireless Terminal) & -MS (Mobile Set)

FWT has a Telephone Set and a Base Module. The

Base Module has ports for connecting FAX andModems for Data Communications. It has a di-poleantenna and may be connected with a directional

antenna. MS is a portable set with ESN (Electronic Subscriber

Number).

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BRIEF SPEC OF LG WLL SYSTEM

Access Technology used is CDMA

Frequency band-

=> 824-849 Mhz for Up-link

=> 869-894 Mhz for Dn-link RF Channel Bandwidth = 1.25 Mhz

Rx-Tx Separation 45 Mhz

Modulation used- QPSK

Voice Coding used- QCELP (Qualcomm Code Excited

Linear Prediction).

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MSC BASED WLL

In BSNL Networks, MSC based WLL Systems aresupplied by M/S ZTE of China.

The System sub-units are

-MSC/VLR/SSP-Charging Centre

-Network Management

-HLR/AUC

-SC/VM-CCS#7 Network

-BSS consisting of BSC & BTS

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Overall system architecture

MSC/VLR/SSP SC/VMHLR/AUC

OMC-S Network

management

Charging

centre

BSS

OTHER

NETWORKS

A

MSC BASED WLL SYSTEM (ZTE MAKE)

CCS#7 NETWORK

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CDMA2000

CDMA2000 is the 3G Mobile Technologyupgraded from CDMAone (IS-95 standard).

It is standardized by 3GPP2 (Third Generation

Partnership Project 2). There are various types of CDMA2000-

-CDMA2000 1X

-CDMA2000 1X-EV-DO

-CDMA2000 1X-EV-DV

-CDMA2000 3X

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CDMA2000 (Contd.)

CDMA 1X

This delivers 3G Like Services with dataspeed up-to 140 kbps.

CDMA 1X EV-DO Here, EV-DO stands for Enhanced

Video-Data Only. It is EV Phase One. Its data speed is

of the order of 2 mbps.

CDMA 1X EV-DV In this case EV-DV is meant for

Enhanced Video Data and Voice. It is EV Phase

Two. Data Speed is of the order of 3 mbps.

CDMA 3X It is other way known as IMT-2000 MC

(Multi Carrier). It band width is 3.75 Mhz and Data

speed is of the order of 2 to 4 mbps.

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THANKS