LG LGC500W Service Manual

CDMA PORTABLE CELLULAR PHONE

LGC-500W

SERVICE MANUAL

LGIC

LG Information & Communications, Ltd.

LGC-500W

LG Information & Communications, Ltd.

Table of Contents

General Introduction

.............................................................................................................................................................. 2

CHAPTER 1. System Introduction

1. System Introduction ......................................................................................................................................

2. Features and Advantages of CDMA Mobile Phone (For AMPS as well) .....................................................

3. Structure and Functions of CDMA Mobile Phone (For AMPS as well) .......................................................

4. Specification ..................................................................................................................................................

5. Installation .....................................................................................................................................................

CHAPTER 2. NAM Input Method(Inputting of telephone numbers included)

1. Telephone Number and NAM Programming Method ...................................................................................

CHAPTER 3. Circuit Description

1. RF Transmit/Receive Part .............................................................................................................................

2. Digital/Voice Processing Part .......................................................................................................................

Appendix

.................................................................................................................................................

1. Assembly and Disassembly Diagram

2. Block & Circuit Diagram

3. Component Layout

4. Part List

5. Accessories

- Desktop Charger

- Travel Charger

- Cigar Lighter Charger

- Hands Free Kit

6. WLPST ( LGIC Product Support Tool For Win95 )

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LGC-500W

LG Information & Communications, Ltd.

General Introduction

The LGC-500W cellular phone functions as both analog cellular phone worked in AMPS (Advanced Mobile Phone Service) mode and digital cellular phone worked in CDMA (Code Division Multiple Access) mode.

CDMA mode applies the DSSS (Direct Sequence Spread Spectrum) technique that has been used in military. This technique enable to share one frequency channel with many users in the same specific area. As a result, that it increases the capacity 10 times more compared with that in the analog mode (AMPS) currently used.

Soft/Softer Handoff, Hard Handoff, and Dynamic RF power Control technologies are combined into this phone to reduce the call being interrupted in a middle of talking over phone.

CDMA digital cellular network consists of MSC (Mobile Switching Office), BSC (Base Station Controller), BTS (Base station Transmission System), and MS (Mobile Station). Communication between MS and BTS is designed to meet the specification of IS-95A (Common Air Interface). MS meets the specifications of the below :

- IS-95A (Common Air Interface) : Protocol between MS and BTS

- IS-96A (Vocoder) : Voice signal coding

- IS-98 : Basic MS functions

- IS-126 : Voice loopback

- IS-99 : Short Message Service, Asynchronous Data Service, and G3 Fax Service

LGC-500W is composed of a transceiver, a desktop charger, two Li-Ion Batteries (1650mAh), a h a travel charger. In digital mode, the hands-free kit is designed to operate in full duplex.

ands-free kit,

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LGC-340/345W

CHAPTER 1. System Introduction

1. Introduction to the Cellular System

1.1 Basic Concept for the Cellular System

The design objective of early mobile radio systems was to achieve a large coverage area by using a single, very high powered transmitter with antenna mounted on the tall tower. While this approach achieved very good coverage, it also meant that it was impossible to reuse those same frequency throughout the system. But the increasing demand for mobile service required the radio telephone system to achieve high capacity with limited radio spectrum, while at the same time covering very large areas.

The cellular concept was a major breakthrough in sloving the problem of spectral congestion and user capacity. The cellular concept ,which starts from the frequency reuse technique, is a system level idea which calls for replacing a single, high power transmitter (large cell) with many low power transmitter(small cells), each providing coverage to only a small portion of the service area. Each base station is allocated a portion of the total number of channels available to the entire system, and nearby base stations are assigned different groups of channels so that all the available channels are assigned to a relative small number of neighboring base stations. Neighboring base stations are assigned different groups of channels so that the interference between base stations (and the mobile users under their control) is minimized. This technique is called channel assignment stategy.

In the cellular system, the channel handoff operation is inevitably needed to keep a call while a user moves one cell to another. This function not only involves identifying a new base station, but also eruires that the voice and control signals be allocated to channel associated with new base station. The handoff between different swithcing systems is called roaming. It is call state can be maintained continuously by the information exchange between switching systems when the busy subscriber moves from one cellular system area to the other cellular system area.

1.2 Multiple Access Techniques for the Cellular System

In cellualr systems, it is often desirable to allow the subscriber to send simultaneously infoermation to the base station while receiving information from the base station. This is called deplexing. Duplexing is done using frequency or time domain rechniques. Frequency Division Duplexing(FDD) provides two distinct bands of freqeuncies for every user. In FDD, any duplex channel actually consist of two simplex channels, and a device called a duplexer is used inside handsets and base stations. Time Division Duplexing(TDD) uses time instead of frequency to provide both a forward and reverse link. If the time split between the forward and reverse time slot is small, then the transmission and reception of data appears simultaneous to the user.

Multiple access techniques are used to share the available channel resources(frequency bandwidth). Frequency Division Multiple Access(FDMA), Time Division Multiple Access(TDMA), Code Division Multiple Access(CDMA) are the three major techniques in cellular systems.

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LG Information & Communications, Ltd.

LGC-340/345W

LG Information & Communications, Ltd.

FDMA allocates a unique frequencys to a channel. These channels are assigned on demand to users who request service. During the period of the call, no other user can share the same frequency band. In FDD systems, the users are assigned a channel as a pair of frequencies; one frequency is used for the forward channel, while the other frequency is used for the reverse channel. This system is called FDD/FDMA system. Most of analog cellular systems(AMPS, E-AMPS, NMT, ETACS, JTACS, etc. ) are FDD/FDMA system.

TDMA systems devide the radio spectrum into time slots, and each slot only one user is allowed to ether transmit or receive. Each user occupies a cyclically repeating time slot, so a channel may be thought of as particular time slot that reoccurs every frame, where N time slots comprise a frame. TDMA systems can apply in both TDD and FDD.

Code Division Multiple Access (CDMA) is a radically new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as an upgrade that will dramatically increase both their system capacity and the service quality. It has likewise been chosen for deployment by the majority of the winners of the United States Personal Communications System spectrum auctions. It may seem, however, mysterious for those who aren't familiar with it. This site is provided in an effort to dispel some of the mystery and to disseminate at least a basic level of knowledge about the technology.

CDMA is a radically new concept in wireless communications. It has gained widespread international acceptance by cellular radio system operators as an upgrade that will dramatically increase both their system capacity and the service quality. It has likewise been chosen for deployment by the majority of the winners of the United States Personal Communications System spectrum auctions. It may seem, however, mysterious for those who aren't familiar with it. This site is provided in an effort to dispel some of the mystery and to disseminate at least a basic level of knowledge about the technology.

CDMA is a form of spread-spectrum, a family of digital communication techniques that have been used in military applications for many years. The core principle of spread spectrum is the use of noise-like carrier waves, and, as the name implies, bandwidths much wider than that required for simple point-to-point communication at the same data rate. Originally there were two motivations: either to resist enemy efforts to jam the communications (anti-jam, or AJ), or to hide the fact that communication was even taking place, sometimes called low probability of intercept (LPI). It has a history that goes back to the early days of World War II.

The use of CDMA for civilian mobile radio applications is novel. It was proposed theoretically in the late 1940's, but the practical application in the civilian marketplace did not take place until 40 years later. Commercial applications became possible because of two evolutionary developments. One was the availability of very low cost, high density digital integrated circuits, which reduce the size, weight, and cost of the subscriber stations to an acceptably low level. The other was the realization that optimal multiple access communication requires that all user stations regulate their transmitter powers to the lowest that will achieve adequate signal quality.

CDMA changes the nature of the subscriber station from a predominately analog device to a predominately digital device. Old-fashioned radio receivers separate stations or channels by filtering in the frequency domain. CDMA receivers do not eliminate analog processing entirely, but they separate communication channels by means of a pseudo-random modulation that is applied and removed in the digital domain, not on the basis of

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LGC-340/345W

LG Information & Communications, Ltd.

frequency. Multiple users occupy the same frequency band. This universal frequency reuse is not fortuitous. On the contrary, it is crucial to the very high spectral efficiency that is the hallmark of CDMA. Other discussions in these pages show why this is true.

CDMA is altering the face of cellular and PCS communication by:

Dramatically improving the telephone traffic (Erlang) capacity

Dramatically improving the voice quality and eliminating the audible effects of multipath fading

Reducing the incidence of dropped calls due to handoff failures

Providing reliable transport mechanism for data communications, such as facsimile and internet traffic

Reducing the number of sites needed to support any given amount of traffic

Simplifying site selection

Reducing deployment and operating costs because fewer cell sites are needed

Reducing average transmitted power

Reducing interference to other electronic devices

Reducing potential health risks

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LGC-340/345W

LG Information & Communications, Ltd.

2. Features and Advantages of CDMA Mobile Phone (For AMPS as well)

2.1 Various Types of Diversities

When employing the narrow band modulation (30kHz band) that is the same as the analog FM modulation system used in the existing cellular system, the multi-paths of radio waves create a serious fading. However, in the CDMA broadband modulation(1.25MHz band), three types of diversities (time, frequency, and space) are used to reduce the multi-path fading problems generated from radio channels in order to obtain high-quality calls.

Time diversity can be obtained through the use of code interleaving and error correction code whereas frequency diversity can be obtained by spreading signal energy to more wider frequency band. The fading related to normal frequency can affect the normal 200~300kHz among signal bands and accordingly, serious affect can be avoided. Moreover, space diversity (also called path diversity) can be realized with the following three types of methods. First, it can be obtained by the duplication of cell site receive antenna. Second, it can be obtained through the use of multi-signal processing device that receives a transmit signal having each different transmission delay time and then, combines them. Third, it can be obtained through the multiple cell site connection (Soft Handoff) that connects the mobile station and more than two cell sites at the same time.

2.2 Power Control

The CDMA system utilizes the forward (from a base station to mobile stations) and backward (from the mobile station to the base station) power control in order to increase the call processing capacity and obtain high-quality calls. In case the originating signals of mobile stations are received by the cell site in the minimum call quality level (signal to interference) through the use of transmit power control on all the mobile stations, the system capacity can be maximized. If the signal of mobile station is received too strong, the performance of that mobile station is improved. However, because of this, the interference on other mobile stations using the same channel is increased and accordingly, the call quality of other subscribers is reduced unless the maximum accommodation capacity is reduced. In the CDMA system, forward power control, backward open loop power control, and closed loop power control methods are used. The forward power control is carried out in the cell site to reduce the transmit power on mobile stations less affected by the multi-path fading and shadow phenomenon and the interference of other cell sites when the mobile station is not engaged in the call or is relatively nearer to the corresponding cell site. This is also used to provide additional power to mobile stations having high call error rates, located in bad reception areas or far away from the cell site. The backward open loop power control is carried out in a corresponding mobile station; the mobile station measures power received from the cell site and then, reversely increases/decreases transmit power in order to compensate channel changes caused by the forward link path loss and terrain characteristics in relation to the mobile station in the cell site. By doing so, all the mobile office transmit signals in the cells are received by the cell site in the same strength. Moreover, the backward closed loop power control used by the mobile station to control power with the commands issued out by the cell site. The cell site receives the signal of each corresponding mobile station and

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LGC-340/345W

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compares this with the pre-set threshold value and then, issues out power increase/decrease commands to the corresponding mobile station every 1.25 msec (800 times per second). By doing so, the gain tolerance and the different radio propagation loss on the forward/backward link are complemented.

2.3 Voice Encoder and Variable Data Speed

The bi-directional voice service having variable data speed provides voice communication which employs voice encoder algorithm having power variable data rate between the mobile telephone cell site and mobile station. On the other hand, the transmit voice encoder performs voice sampling and then, creates encoded voice packets to be sent out to the receive voice encoder, whereas the receive voice encoder demodulates the received voice packets into voice samples. One of the two voice encoders described in the above is selected for use depending on inputted automatic conditions and message/data; both of them utilize four-stage frames of 9600, 4800, 2400, and 1200 bits per second. In addition, this type of variable voice encoder utilizes adaptive threshold values when selecting required data rate. It is adjusted in accordance with the size of background noise and the data rate is increased to high rate only when the voice of caller is inputted. Therefore, background noise is suppressed and high-quality voice transmission is possible under the environment experiencing serious noise. In addition, in case the caller does not talk, data transmission rate is reduced so that the transmission is carried out in low energy. This will reduce the interference on other CDMA signals and as a result, improve system performance (capacity, increased by about two times).

2.4 Protecting Call Confidentiality

CDMA signals have the function of effectively protecting call confidentiality by spreading and interleaving call information in broad bandwidth. This makes the unauthorized use of crosstalk, search receiver, and radio very hard substantially. Also included is the encryption function on various authentication and calls specified in IS-95 for the double protection of call confidentiality.

2.5 Soft Handoff

The handoff , which is basic function of the cellular system, can maintain a call when user moves one cell site to another. In analog cellular, the cell sites use different frequecy channel, the handoff means frequence change. This mechanism also uses in CDMA. CDMA has many Frequency Allocation(FA)s. When the handoff carry out between different Fas, it is called Hard Handoff. The soft handoff means the handoff without change of the FA.

During the soft hand, the cell site already in the busy state and the cell site to be engaged in the call later participate in the call conversion. The call conversion is carried out through the original call connection cell site, both cell sites, and then, new cell site. This method do not change frquency , so minimize call disconnection and prevent the user from detecting the hand-off.

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LGC-340/345W

LG Information & Communications, Ltd.

2.6 Frequency Re-Use(Segmentation) and Sectorization

Unlike the existing analog cellular system, the CDMA system can reuse the same frequency at the adjacent cell and accordingly, there is no need to prepare a separate frequency plan. Total interference generated on mobile station signals received from the cell site is the sum of interference generated from other mobile stations in the same cell site and interference generated from the mobile station of adjacent cell site. That is, each mobile station signal generates interference in relation to the signals of all the other mobile signals. Total interference from all the adjacent cell sites is the ratio of interference from all the cell sites versus total interference from other mobile stations in the same cell site (about 65%). In the case of directional cell site, one cell normally uses a 120¡Æsector antenna in order to divide the sector into three. In this case, each antenna is used only for 1/3 of mobile stations in the cell site and accordingly, interference is reduced by 1/3 on the average and the capacity that can be supported by the entire system is increased by three times.

2.7 Soft Capacity

The subscriber capacity of CDMA system is flexible depending on the relation between the number of users and service classes. For example, the system operator can increase the number of channels available for use during the busy hour despite the drop in call quality. This type of function requires 40% of normal call channels in the standby mode during the handoff support, in an effort to avoid call disconnection resulting from the lack of channels. In addition, in the CDMA system, services and service charges are classified further into different classes so that more transmit power can be allocated to high class service users for easier call set-up; they can also be given higher priority of using hand-off function than the general users.

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