1

on

From

Submitted To :GYAN VIHAR SCHOOL OF ENGINEERING AND

TECHNOLOGYJAGATPURA, JAIPUR

Affiliated to RAJASTHAN TECHNICAL UNIVERSITY, KOTA

In Partial fulfillment of the requirement for the

Degree ofBachelor of Engineering

Submitted by :

DEEPAK MODIFinal yearr B. Tech.

Electrical Engg.

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Acknowledgement

With profound respect and gratitude, I take the opportunity to convey my thanks to complete the training here. I do extend my heartfelt thanks to Ms. Anubha for providing me this opportunity to be a part of this esteemed organization. I am extremely grateful to all the technical staff of Genus Power Infrastructure Ltd., Jaipur for their co-operation and guidance that helped me a lot during the course of training. I have learnt a lot working under them and I will always be indebted of them for this value addition in me. I would also like to thank the training in charge of GYAN VIHAR School Of Engineering & Technology, Jaipur.

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Company Profile

Genus Power Infrastructures Ltd. an ISO 9001: 2000 Public Limited Company forms an integral part of the reputed 300 million USD Kailash Group. The company primarily deals in manufacturing and distribution of Electronic Energy Meters, Power Distribution Management Projects, Hybrid microcircuits, Inverters, Batteries, Home UPS and Online UPS across India as well as globally.

Equipped with avant-garde facilities and a team of highly qualified and experienced scientists, it is committed to develop complex technologies at an affordable price. It’s top-notch R&D laboratory, approved by the Ministry of Science and technology, Govt. of India, has enabled the company to dominate the power infrastructure and electronics segment’s engineering domain.

As a step forward Genus has launched IT enabled Distribution Transformer Metering System, Feeder Monitoring and Management System, Smart Street Light Management System with value added software application for providing end to end solutions for energy management. The high-end software developed by us has transformed the way metering is done, not only in India but globally as well.

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INTRODUCTION

The purpose of this document is to introduce guidelines for CDMA2000 inter-carrier packet data roaming through use of a 3rd Party provider’s exchange hub.  CDG Reference Document titled “Wireless Data Roaming Requirements and Implementation Guide” sets forth the general principles for CDMA2000 packet data roaming using a direct connection between two roaming partners.  Carriers shall have two options in the future – to inter-connect directly with roaming partners or to leverage the services of 3rd Party service providers’ exchange hubs.  This document defines the interfaces between the carrier and the 3rd Party provider(s) and how the 3rd Party service providers’ exchange hubs must perform.  One objective is to ensure that 3rd Party providers will be prepared to offer commercial service to carriers prior to the end of Q3 2004.

The assumptions and scope for this document include the following:

IS-835-A is used as the baseline standard

A number of IP connection scenarios will be addressed

o Simple IPo Mobile IP

The visited operator will generate the accounting records required for retail billing.  Generation of retail billing not based on RADIUS accounting records will not be addressed.

Peering among 3rd Party providers shall be required.

1xRTT shall be supported in this document.  The support of other air interface technologies within the CDMA2000 family of standards (e.g., 1xEV-DO) will be addressed in a future release of the document.

CDMA2000 to CDMA2000 packet data roaming shall be defined initially, however this document shall also identify the hooks for follow-on CDMA2000 to GPRS service.

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General Requirements for CDMA Packet Data Roaming

 This section describes generic requirements for a 3rd Party to support CDMA packet data roaming. It specifies the reference model, the interface definition, IP addressing and routing, QoS, security as well as the peering requirement.

Reference Model

CDMA Packet Data Roaming allows 3rd Party, i.e., CDMA Roaming eXchange (CRX) Provider, to facilitate service between visited and home CDMA2000 packet data systems without requiring bilateral roaming (i.e., direct connectivity).  The services, or service elements, defined in the guidelines include: 

IP Data Transport Authentication, Authorization, and Accounting (AAA) RADIUS Data Clearing and Financial Net Settlement.

 It contains these interfaces :

Xd:  IP layer interface for IP data transport

Xa:  Application layer interface for Authentication, Authorization and Accounting (AAA) messages

Xi:  Application layer interface for accounting data to data clearing system Each interface, between a CDMA2000 packet data system and a 3rd Party is a separate CDMA packet data roaming service. The LAC and LNS functions are optional.  

The operator may choose a subset of the services available from the 3rd Party.  For example, the operator may

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choose the 3rd party only for the data clearing service and rely on other IP data transport means (e.g., Internet).

Interface Xd

Interface Xd refers to the IP layer Interface between a CDMA2000 packet data system’s Border Gateway and the CRX provider’s Border Gateway. This interface carries traffic exchanged between a CDMA2000 packet data system and CRX provider, including

IP Routing Traffic

Tunnelling traffic between Visited and Home CDMA2000 packet data systems 

o L2TP tunnel traffic between LAC and LNS

o MIP tunnel traffic between FA and HA.

AAA RADIUS traffic defined in interface Xa

Future traffic, such as

o Interworking traffico Tunnelling traffic for inter-standard roaming

between GPRS/GSM (or GPRS/UMTS) and CDMA2000 packet data systems.

CDMA2000 packet data systems use the Xd Interface to access the CRX IP transport service. The access interface Xd must be implemented using either IPSec or Lease Line Circuit (LLC) to assure the lateral security.  In addition to the firewalls required in the CDMA2000 packet data system, the CRX provider needs to maintain the firewall and filtering at the edge devices of the CRX provider network.  

For the IP transit within the CRX provider, it is required to maintain all levels of security to ensure the security service.

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Interface Xa

Interface Xa refers to the application interface between the CDMA2000 packet data system’s AAA server and CRX provider’s Proxy AAA server. This link carries authentication/authorization/accounting traffic between the Visited and Home CDMA2000 packet data systems. 

The Proxy AAA servers in the CRX provider should route based on the realm of all RADIUS messages associated with roaming services, such as user authentication, authorization and accounting, and tunnel authentication. The “Xa” interface can be offered as a bundled service with IP transport or as a Proxy-AAA only service from the CRX provider.  For either case, AAA RADIUS traffic over the logical link in the Xa interface shall be carried through the physical Xd interface, with assured security guarantee.

The CRX provider may offer data clearing service using the raw UDR in RADIUS format between visited and home CDMA2000 packet data systems as part of packet data roaming service.

Interface Xi

The “Xi” Interface refers to the application layer interface, required to exchange raw UDR in RADIUS Accounting format with data-clearing service provider when visited and home CDMA2000 packet data systems select their respective CRX or data-clearing service providers for their packet data roaming services.  This interface should only support RADIUS Accounting packets.

IP Addressing Requirement

A public IP address should be used for each service element that participates in the packet data roaming, including visited and home CDMA2000 packet data systems as well as CRX providers.

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The elements requiring public IP address are:

PDSN/LAC and LNS,

PDSN/FA and HA,

AAA Sever and Proxy AAA Server,

Application servers (e.g., WAP gateway, mail server, etc.),

Border Gateway.

Mobile Station.

Using public addressing means that each party has a unique address space officially reserved from the Internet addressing authority. However, public addressing does not mean that these addresses should be visible to the Internet.  These roaming service elements should remain invisible and inaccessible from the public Internet.

IP Routing Requirement

Each participating mobile network should exchange IP routing information with its CRX provider in order to route the IP packets between the CRX provider network and the CDMA2000 packet data system. The CRX providers should manage the IP routing information obtained from a particular CDMA2000 packet data system and is responsible for announcing it to other CDMA2000 packet data systems on behalf/request of that particular CDMA2000 packet data system.  The home network does not need to exchange routing information with the visited systems directly. 

BGP-4 IP routing protocol is recommended to dynamically exchange routing information between the Border Gateways of CRX provider and the CDMA2000 packet data systems via the “Xd” interface.  Static routing is also feasible if BGP-4 protocol is not supported by the home network.  

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Security Requirement

In order to ensure the proper level of security within the packet data roaming infrastructure, the following requirements for CDMA2000 packet data systems and CRX providers are recommended:

Both CDMA2000 packet data systems and CRX providers should implement firewalls in the Border Gateways.

The IP addresses that are assigned to those service elements participating in the packet data roaming should be invisible (i.e., not routable) to the Internet.

The IPSec connections between CDMA2000 packet data systems and CRX providers are required if direct leased-line connections (e.g., FR, ATM, IPLC) are not available.

The CDMA2000 packet data systems and CRX providers together should be responsible for prevention of IP address spoofing.

Quality of Service

In order to maintain the required performance of network and application, Quality of Service (QoS) should be specified and offered by the CRX provider.  The QoS definition consists of physical characteristics of the network level performance parameters (delay, packet loss, and jitter), and application level performance parameters (response time, and throughput).

In general, each service provided by the CRX provider should have its own QoS defined, such as QoS for IP data transport, for AAA Proxy, as well as for data clearing.  The parameters defined in a QoS should be agreed upon between a CDMA2000 packet data system and its CRX provider jointly.

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Peering Requirement

A CRX provider should arrange peering with other CRX providers directly so that any CDMA2000 packet data system connected to a CRX provider can reach any other CDMA2000 packet data system.  A CRX provider should guarantee that its network is reliable and the traffic exchanged over Xd and Xa interfaces can be routed to CDMA2000 packet data systems connected to other CRX providers.

In addition to the QoS committed to its directly connected CDMA2000 packet data systems, CRX providers should define QoS among themselves to ensure the QoS across multiple CRX provider networks without compromising the end-to-end services.

It is recommended to have no more than two CRX providers between the visited and home CDMA2000 packet data systems.  Figure 2 shows the CRx peering reference model.

Network Connectivity and Interconnection

Interconnectivity between CDMA2000 packet data systems can be implemented in two ways:

Direct bilateral interconnection Interconnection via CRX providers

Although direct interconnections can be considered for CDMA to CDMA roaming, interconnection via a CRX provider is scalable and cost effective for CDMA to CDMA roaming, as well as expandable to inter-standard GPRS/CDMA roaming.

Network Connection Options

In principle, there should be three types of network connections between the CDMA packet data system’s Border Gateway (Access Router, or CPE) and the CRX provider’s Border Gateway (Edge Router):

Layer 1 connection (i.e., leased line or fiber),

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Layer 2 logical connection (i.e. ATM, LAN, FR), or Layer 3 IP VPN connection over public Internet (IPSec

is recommended)

It is recommended that the CRX provider supports all of the connection options. It is up to the CDMA2000 packet data system o choose the connection type.

The IPSec implementation must meet the following requirements:

1. The default encryption algorithm   is DES [10]. The encryption algorithm 3DES, which is stronger than DES, may be used.

2. The IPSec packet format should be ESP in tunnel mode [11]; and

3. The IPSec implementation should exchange encryption keys either manually or by IKE [12].

IP Addressing and Routing

The CRX provider and their connected CDMA2000 packet data systems should comply with IP addressing guideline specified in section 2.2 

Each CRX provider should indicate its Border Gateway’s IP address to the CDMA2000 packet data system’s Border Gateway, and assign an IP address to the CDMA2000 packet data system’s Border Gateway. The addressing should be from the Public IP address space. BGP-4 is recommended as the IP routing protocol between CDMA2000 packet data system’s Border Gateway and the CRX provider’s Border Gateway to dynamically exchange the IP routing information.  BGP-4 dynamically announces the IP routes between CDMA2000 packet data systems via the CRX provider, and can also be used among multiple CRX providers connecting to the same CDMA2000 packet data system.  

If CDMA2000 packet data systems prefer to use static routing, the CRX provider should be able to support static routing. 

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The CRX provider should support BGP-4 protocol and static routing.  It is up to the CDMA2000 packet data system to choose the IP routing protocol.

It is recommended that the CDMA2000 packet data systems follow with the BGP advertisement rules below:

No host specific route (no mask /32 advertisements) should be advertised between the Border Gateway of the CDMA2000 packet data system and the Border Gateway of the CRX provider.

The IP route advertisement should be aggregated as much as possible.

Each CDMA2000 packet data system should only advertise its own core public IP address range to the CRX provider, for example, only the aggregated IP route address range containing the IP addresses of the PDSN, LAC, LNS, FA, HA, AAA, MS, and application servers should be announced.

IP route address range advertised from CDMA2000 packet data systems should only contain the IP routes that originate from its own Autonomous System (AS) number, owned by the CDMA2000 packet data system.

CRX IP Transit Backbone

The CRX IP transport backbone should ensure the IP transport services for IP data packets associated with the CDMA Packet Data roaming.  The construction of the IP transit backbone is to the responsibility CRX provider.

The CRX IP transport backbone should ensure the IP packet exchanges with other CRX providers for CDMA packet data roaming, and other GRX (GPRS Roaming exchange) providers for inter-standard CDMA/GPRS roaming. The IP packet exchange between CRX providers should use BGP-4 to dynamically advertise the IP routes learned from each individual CRX provider.

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The CRX IP transport backbone should insure the security and QoS for the IP packets carried within its own IP backbone network.  This network should be invisible to the Public Internet and inaccessible from the Public Internet.

Autonomous System Number (ASN)

BGP4 dynamic routing requires an ASN as the ID for each domain of an IP network, such as operator’s CDMA network. To avoid the potential conflict for the ASN associated with the IP routing information during the CDMA roaming exchange, it is recommend to use “public ASN” instead of private ASN.

Roaming Scenarios

The IP data transport services provided by the CRX provider should support different roaming scenarios that may exist among CDMA2000 packet data systems.   The details of the roaming scenarios are described in the sections below.

Simple IP Roaming

This roaming scenario refers to a Simple IP capable mobile station roaming into a visited CDMA2000 packet data system where Simple IP is supported.   Several possible use cases may exist:

1. If the mobile station needs to access home services residing in the home CDMA2000 packet data system, it is recommended that the visited CDMA2000 packet data system assigns an IP address to the roaming mobile station and routes the user payload traffic through the CRX IP backbone to the home CDMA2000 packet data system.  The CRX providers should manage the IP routing to ensure that the visited CDMA2000 packet data system and the home network can reach each other via the CRX IP backbone.

2. Optionally, L2TP tunnel between the visited and home CDMA2000 packet data systems may be used for the

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mobile station to access home services residing in the home CDMA2000 packet data system.  In this case, the home CDMA2000 packet data system assigns an IP address to the roaming mobile station.  The CRX providers should manage the IP routing to ensure that the PDSN/LAC at the visited CDMA2000 packet data system and LNS at the home CDMA2000 packet data system can reach each other via the CRX IP backbone.

3. If accessing the home services that reside in the home CDMA2000 packet data system is not required, it is recommended that the visited CDMA2000 packet data system assigns an IP address to the roaming mobile station and routes the user payload traffic to the Internet directly without traversing through the CRX IP backbone.  Only authentication and accounting packets are allowed to traverse the CRX IP backbone to the home CDMA2000 packet data system.

To avoid conflict of IP addresses among CRX providers, the destination addresses of the application servers (e.g., WAP Gateways, Mail-servers, AAA server, DNS) should be public IP addresses.  The mobile station may be assigned with a public or private IP address.  If L2TP tunneling is not enabled, and if the mobile station is assigned with a private IP address, the address must be translated to a public IP address before the IP packet is sent to the CRX provider.

Mobile IP Roaming

This roaming scenario refers to a Mobile IP capable mobile station roaming into a visited CDMA2000 packet data system where Mobile IP is supported.  The CRX provider should manage the IP routing between PDSN/FA in the visited CDMA2000 packet data system and HA in the home CDMA2000 packet data system.  Since the CRX backbone is a secured and closed network, invisible and unreachable from the public Internet, IPSec between the PSDN/FA and HA is not needed, for the purpose of reducing unnecessary headers and providing better network performance.  The

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CRX provider should also manage and support tunneling used between the PDSN/FA and HA. 

Data Exchange Interface between third parties (CRXs)

Because CDMA2000 packet data systems can choose roaming service elements from different CRX providers, the serving CRX providers are required to open up interfaces among themselves in order to fulfill the end-to-end packet data roaming traffic across multiple CRX IP backbones.  In a scenario where both visited and home CDMA2000 packet data systems are served by two different CRX providers, there is a need to interconnect the CRX providers via the following interfaces:

Interface “Xd”: This interface should be allowed to exchange IP data traffic from each other via central peering point described earlier. 

Interface “Xa”: This interface should be allowed to exchange RADIUS messages between the peering CRX providers’ Proxy AAA servers over the peering interface “Xd”.  This requires peering CRX providers to exchange domain routing information with each other.

Interface “Xi”:  This interface is required to ensure a delivery mechanism for raw roaming UDR from a CRX provider to a data clearing system.  The CRX provider should make the raw roaming UDR available to a data clearing system that may or may not belong to that CRX provider.

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Data Clearing and Settlement

The CRX reference model 1 for data clearing and settlement. In Model 1, the settlement service may be provided by a service provider other than the CRX provider, as shown in the figure.  In this case, the CRX provider and the settlement service provider should support the Xf interface.  The data clearing system in the CRX provider prepares the financial information (settlement report) and sends it to the financial settlement  provider.  An example of the financial information format is given in Appendix 4. The communication link for the Xf interface shall be secured from the public Internet.  No specific requirement is imposed on the protocol used for exchanging the financial information over this interface.

MULTIPLE ACCESSS TECHNIQUE

Multiple Access is the technique by witch numbers of users can share a same transmission mediumsame time.

There are following Multiple Access Technique:

(1) TDMA (Time Division Multiple Access)

(2) FDMA (Frequency Division Multiple Access)

(3) CDMA (Code Division Multiple Access)

Frequency Division Multiple Access

In this technique Subscriber can use same medium for communication, but they assigned specified frequency range for every user. i.e. different frequency for different users.

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This is efficient when Band width of channel is equal to frequency of signal which being transmitted.

Time Division Multiple access

In this technique Subscribers shared a common frequency channel for a assign time slot. In this time slot user is capable to Transmit & Receiving data. If user is free ,no any user can use this channel during time slot.

Code Division Multiple Access

In this technique Subscriber use a common channel at same frequency, but their transmission codes are different. The codes are shared by both the mobile station (cellular phone) and the base station.

CDMA users are uniquely identified by a code sequence embedded as an address with in the carrier waveform, which gives the receiver the capability of selective addressing. To recover a signal, the receiver correlates the sum of incoming signals against address sequences. This process maximizes the output for the signal matching the address sequence. However the receiver must have the knowledge of the address sequence.

To achieve isolation between CDMA users, it is necessary to select code sequences with Properties by which a correlation process would build up the signal of the matching sequence while maintaining the low correlation values for non matching sequences.

The CDMA scheme was developed mainly to increase the capacity. For cellular telephony, CDMA is a digital multiple access techniques specified by the Telecommunication Industry

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Association as “IS 95”.

IS 95 is define as compatibility standard wide band spread spectrum cellular mobile telecommunications(1800MHz band). It describes the generation of Channels, Power control, Call processing, Hand off process.

BTS (Base Station Trans receiver System):

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A base transceiver station or cell site (BTS) is a piece of equipment that facilitates wireless communication between user equipment (UE) and a network. UE are devices like mobile phones (handsets), WLL phones, computers with wireless internet connectivity, Wify , etc.

The network can be that of any of the wireless communication technologies like GSM CDMA ,etc. BTS is also referred to as the radio base station (RBS), node B (in 3G Networks) or, simply, the base station (BS).

Profile of B.T.S

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Frequency Band (800-1800Mhz).

International Standard Compatible (S-97/J-STD008).

R.F. out power up to 43db/sector.

Flexible Configuration (multiple FA and secsstor Antenna Diversity).

Physical Channels up to 100.

NETWORK DAIGRAM:

HandOff Mechnism In CDMA

In a mobile network, Handoff (also known as Handover) refers to the mechanism of transferring a call carrying voice,

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data or video in communication session from one base station to another geographically-adjacent base station in order to maintain uninterrupted communication for mobile users.

In a cellular communication network, a mobile communication device such as a cellular phone always remains within the range of at least one base station during communication. The area covered by a base station is referred to as a “Cell”. Often, a mobile communication device is within the range of more than one base station causing a number of cells to overlap. Therefore a typical cellular communication network is designed to optimize the flow of signals to the most appropriate base station during communication.

As a mobile communication device moves from a cell to another cell, handoff needs to be implemented for smooth communication to take place session with no interruption. Also, when the capacity of a particular cell is saturated owing to call inflows or a new communication session originating from an area overlapped by another cell, there is need for the transition of the communication session to a cell which is relatively free, in order to prevent interruption in communication.

Types of Handoff

Handoff mechanism is usually categorized into two type namely Hard Handoff and Soft handoff.

Hard Handoff

A Hard handoff, also known as Break-before-Make, is employed by first disconnecting with the base station before switching to another base station in a communication network. This type of handoff mechanism is particularly suitable for delay-tolerant communications. A Hard handoff can be practically employed with more efficiency in FDMA (Frequency Division Multiple Access) and TDMA(Time Division Multiple Access) network access

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systems, because in these systems channel interference is minimized since different frequency ranges are used from adjacent channels.

Soft Handoff

A Soft handoff, also known as Make-before-Break, is employed by first switching and establishing connection with another base station before disconnecting from the existing base station in the network. This type of handoff mechanism is particularly suitable for handling voice-centric cellular networks (particularly CDMA or GSM) and latency-sensitive communication services such as Videoconferencing.

A Hard handoff is less expensive to implement compared to to soft handoff and is generally more spectral (network bandwidth) efficient, particularly, in heavy data traffic environments.

CDMA Forward channels:

Pilot channel:

The pilot channel is used by the mobile unit obtained initial system synchronization and to provide time, frequency, and phase tracking of signal from the site.

Sync channel :

This channel provide cell site identification, pilot transmitted power, and the cell site pilot phase offset information I With this information the mobile units can establish the System Time as well as proper transmitted power level to use to initiate a call.

Forward Traffic channel :

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This channel carries the actual phone call and carries the voice and mobile power control information from the base station to the mobile unit.

CDMA Reverse channel :

Access channel:

When the mobile unit is not active on a traffic channel, it will communicate to the base station over the access channel. This communication includes registration requests, responses to pages, and call origination.

Reverse Traffic channel :

This channel carries the other half of the actual phone call and carries the voice and mobile power control information from the mobile unit to the base station.

Power Control & Management Technique :

Power Control and Management techniques has to achieve:

Reduce the transmitted power of both mobile and base station.

Received power level of signal from all mobile should be same at the base station.

Optimize the Network resources.

Power Control technique will achieve both a and b, Power Management Technique will achieve c.

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There are 4 Power Control Techniques, which are below:

Reverse Link Open loop Power control .

Reverse Link Close loop Power Control.

Reverse Outer loop Power Control.

Forward Link Power Control.

Reverse Link Power Control:

Open Loop Control:

This can be use to handle wide dynamic range. The mobile initially estimates the required transmitted power based on the received power at the mobile and access parameters provided by the base station.

The mobile estimates the path loss to the cell by measuring the received signal in terms of analog AGC (Automatic Gain Control) voltage.

The received AGC loop holds constant the total power entering its 1.25 MHZ . IF pass band (which includes signal, thermal noise and interference).

The measured front-end power is adjusted by a closed loop correction and then used to control the mobile transmitted power accordingly. But this will not.

Closed Loop Control:

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Closed power control is a correction applied to the open loop power estimate. In this case, the cell measure the received Eb/No and compares it to a point (set by a cell function).

If the measured Eb/No is above the set point, then a “down" command is sent, other wise a “up” command is sent .The base station directs the mobile to increase or decrease transmit power of mobile.

The mobile cell change its transmit power accordingly. the mobile power by one db, depending on the open loop estimate. The command are sent every 1.25ms.The dynamic range of the closed loop control is +-24 db relative to the open loop estimate.

At the boundary of a cell site, the mobile receive the power control commands from both base station and the will increase its transmit power only if both the base station’s command the mobile to increase the transmit power otherwise the mobile will decrease its transmit power.

Advantages :

Outstanding Voice and Call Quality :

CDMA filters out background noise, cross-talk, and interference so you can enjoy crystal Clear voice quality, greater privacy, and enhanced call quality. QUALCOMM's CDMA variable rate Vocodar translates voice in to digital transmissions, zeroes and ones, at the highest translation rates Possible (8kbps or 13kbps). This allows for crystal clear voice and also maximizes your system capacity.

Greatest Coverage for Lower Cost:

CDMA spread spectrum signal provides the greatest

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coverage in the wireless industry Allowing networks to be built with far fewer cell sites than is possible with other wireless technologies.

Fewer cell sites translates to reduced operating expenses, which results in savings to both operators and consumers.

Packet Data:

CDMA networks are built with standard IP packet data protocols. Other networks require Costly upgrades to add new data equipment in the network and will require new data phones.

Standard CDMA One phones already have TCP/IP and PPP protocols built into them.

Longer Talk Time, Longer Battery Life and Smaller Phones :

You can leave your phone on with CDMA. CDMA uses power control to monitor the amount of power your system and handset need at any time. CDMA handsets typically transmit at the lowest power levels in the industry allowing for longer battery life which results in longer talk time and standby time. CDMA handsets can also incorporate smaller batteries, resulting in smaller, lighter weight phones. Easier to carry, Easier to use.

Fewer Dropped Calls

CDMA patented "soft handoff," method of passing calls between cells sharply reduces the risk of disruption or dropped calls during a handoff. The process of soft handoff

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leads to fewer dropped calls as 2 or 3 cells are monitoring your call at any given time.

Improved Security and Privacy

CDMA digitally encoded, spread spectrum transmissions resist eaves dropping. Designed with about 4.4 trillion codes, CDMA virtually eliminates cloning and other types of fraud.

Improved Security and Privacy

CDMA digitally encoded, spread spectrum transmissions resist eaves dropping. Designed with about 4.4 trillion codes, CDMA virtually eliminates cloning and other types of fraud.

Greater Capacity

CDMA allows the largest number of subscribers to share the same radio frequencies; helping service Providers increase their profitability. CDMA uses spread spectrum technology which can provide up to 10-20 times the capacity of analog equipment and more than three times the capacity of other digital platforms. With dual-mode phones, CDMA is compatible with other technologies for seamless widespread roaming coverage.

Reduced Background Noise and Interference

CDMA combines multiple signals and improves signal strength. This leads to the near elimination of interference and fading. Both electrical background noise (computer noise) and acoustic Background noise (background conversations are filtered out by using narrow bandwidth which corresponds to the frequency of the human voice. This keeps background noise out of your conversations.

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Limitations:

Near-Far Effect

Asynchronous Transmissions in Uplink Channels

Random Signs in Consecutive Symbols

Multi path Interference

High-Speed Busty-Type Traffic

Rate-Matching Problems

Asymmetric Data Rate in Up- and Down-Links

Sensitivity to Time-Selective Fading

Impaired Power-Efficiency Due to MAI

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Code Allocation Scheme

For code coordination each base station shall use a unique time offset of the pilot pseudonoise (PN) sequence to identify a Forward CDMA Channel. Time offsets may be reused within a CDMA cellular system. Distinct pilot channels shall be identified by an offset index (0 through 511 inclusive). This offset index specifies the offset time from the zero offset pilot PN sequence in multiples of 64 chips. The same pilot PN sequence offset shall be used on all CDMA frequency assignments for a given base station. To distinct signals with PN sequence offsets all base stations should be time synchronized but such synchronization is mandatory requirement for CDMA2000 standard.

Administrations should agree on a repartition of these offset indexes on an equitable basis. In any case, each country can use all codes in the most important part of its own territory.

In border areas, codes will be divided into 6 "index sets" containing each one sixth of the available offset indexes. Each country is allocated three index sets (half of the indexes) in a bilateral case, and two index sets (one third of the indexes) in a trilateral case.

Four types of countries are defined in a way such that no country will use the same index set as any one of its neighbours. The following lists describe the distribution of European countries:

Type country 1: BEL, CVA, CYP, CZE, DNK, E, FIN, GRC, IRL, ISL, LTU, MCO, SMR, SUI, SVN, UKR, AZE, SRB.

Type country 2: AND, BIH, BLR, BUL, D, EST, G, HNG, I, MDA, RUS (Exclave), GEOType country 3: AUT, F, HOL, HRV, MKD, POL, POR, ROU, RUS, S, MLTType country 4: ALB, LIE, LUX, LVA, MNE, NOR, SVK, TUR.

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For each type of country, the following tables and figure describe the sharing of the indexes with its neighbouring countries, with the following conventions of writing:

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Preferential index non-preferential index

Set A Set B Set C Set D Set E Set F Set A Set B Set C Set D Set E Set FCountry 1 2..83 88..168 173..25

3258..33

8343..42

3428..50

9Country 2 2..83 88..168 173..25

3258..33

8343..42

3428..50

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Border 1-2 Border 2-1Zone 1-2-3

Zone 2-3-1

Border 1-3 Border 2-3Zone 1-2-4

Zone 2-1-4

Border 1-4 Border 2-4Zone 1-3-4

Zone 2-3-4

Set A Set B Set C Set D Set E Set F Set A Set B Set C Set D Set E Set FCountry 3 2..83 88..168 173..25

3258..33

8343..42

3428..50

9Country 4 2..83 88..168 173..25

3258..33

8343..42

3428..50

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Border 3-2 Border 4-1Zone 3-1-2

Zone 4-1-2

Border 3-1 Border 4-2Zone 3-1-4

Zone 4-2-3

Border 3-4 Border 4-3Zone 3-2-4

Zone 4-3-1

Figure 1

Because of time shifting mechanism for code generation, the situation when propagation delay may lead to synchronisation of two different base stations signals occurring in some parts of service area. The average diameter of such correlation areas could be up to 245 meters (one chip duration multiplied on light speed). To prevent such situations in border areas it is recommended not to use some codes and to introduce 4 exclusion codes between neigboring index sets what gives 78.125 km propagation path before possible correlation area appears. This precludes any real synchronisation and reduction of code space less than on 5% only in border areas won’t affect network planning.

All codes are available in areas away from the border where the field strengths into the neighbouring country are below the relevant trigger levels.

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A two countries code sharing should be applied or used by base stations that exceed the relevant trigger level (Item 3) of only one neighbouring country. A three countries code sharing should be applied or used by base stations that exceed the relevant trigger level (Item 3) of two neighbouring countries.

In certain specific cases (e.g. AUT/HRV) where the distance between two countries of the same Type number is very small (< few 10s km), it may be necessary to address the situation in bi/multilateral coordination agreements as necessary, and may include further subdivision of the allocated codes in certain areas.

COORDINATION THRESHOLDS

Two types of thresholds should be specified:- trigger level of the predicted mean field strength on the border to

perform code coordination for exact base station, which also correspond to maximum permitted level of the mean field strength on the border for base stations using non-preferential codes;

- maximum permitted level of the mean field strength on the border for base stations using preferential codes.

ECC Report 97 provides maximum permitted level of the mean field strength on the border for CDMA-PAMR base stations for coordinated case when both systems use aligned frequencies and preferential codes. It is proposed to use this level as the maximum permitted level for the case of BS using preferential codes. The deduction layout from ECC Report 97 relevant to this issue is explained below.

To define threshold level for cross border operation of CDMA systems in coordinated case a new principle was proposed which states that a network should not be protected to a greater extent than it would be from its own continuously rolled out network. The studies were undertaken using Monte Carlo modelling. The two CDMA systems were modelled at separation distances which were progressively increased.

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Figure 3

The outage of users in reference cell with permanent capacity was taken as the criteria of coexistence. Nominal outage and nominal capacity was obtained from the modelling of the cell in the completely rolled out network. Then the network was divided in two and only one part was left what caused reduction of self-interference and consequently reduction of outage. Interfering network is situated such way that produces the exact level of interference to return outage to its nominal value. The power level in the middle of separation distance is taken as threshold on the border. Only downlink to downlink case was considered as the worst case.

The permissible interference for duplex technologies was measured in a bandwidth of 25 kHz at a height of 3 metres in 50% of time. The result shown in the study for two CDMA systems is -104.1 dBm. Modelling was undertaken at 450 MHz but the results are applicable over the range of frequencies used by CDMA2000 based systems below 1000 MHz. For the studies in ECC Report 97 the Extended Hata model for subrural environment was used.

Thresholds for duplex systems should be based on the power measured in a 0 dBi antenna, these may be converted to field strengths (as dBuV/m) at the appropriate frequency. The use of a 0 dBi antenna, as a standard for comparison, represents a worst case, particularly at lower frequencies, where 0 dBi antennas are less common. The formula for the conversion of dBm to dBuV/m is:

FdBuV/m = PdBm + 77.21 + 20lg(fMHz)

where PdBm is the power in dB microwatts.

CDMACDMA

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The calculation of relevant field strength level in case of aligned frequencies and preferential codes for CDMA2000 in 450 MHz band is presented below:

Central frequencyof downlink band

Threshold field strength level

on the border (rounded)*

Overall CDMA BS signal strength on the border**

465 MHz 26.5 dBuV/m/ 25 kHz 43.5 dBuV/m/ 1.25 MHzTable 1

* - measured in a bandwidth of 25 kHz at a height of 3 metres in 50% of time.**- measured in a bandwidth of 1250 kHz at a height of 3 metres in 50% of time (recommended).

SEAMCAT model, which was used for cross border studies, is not applicable for uncoordinated case with aligned frequencies because each CDMA receiver in SEAMCAT applies processing gain only to its wanted signal. It is difficult to define accurately real correlation zones because of multi-pass propagation when different delays could occur. Theoretically it could occur almost at any location within victim cell. But to estimate the impact of possible correlation between different BS signals on network performance simplified model is proposed with line-of-sight conditions. To find areas of possible correlation the geometrical problem should be solved. The areas where the following conditions are true should be defined as:

Ri-15.625-0.120≤Rv≤ Ri-15.625+0.120 (correlation with the adjacent PN offset)Ri-2*15.625-0.120≤Rv≤ Ri-2*15.625+0.120 (correlation with the second adjacent PN offset)Ri-3*15.625-0.120≤Rv≤ Ri-3*15.625+0.120 (correlation with the third adjacent PN offset).

Where Ri is the distance from interfering BS and Rv is the distance from investigated victim BS. All areas are limited to victim cell circle. The case of same PN offset interference is possible only for overlapping cells which is improbable for cross border situation and not defined in the above conditions. The geometrical networks representation for estimating such areas is shown below. 5.9 km cell radii and omni antennas were considered which is in agreement with parameters used in cross border study.

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Figure 4Different interfering cells create different impact in victim cells. For one

fixed separation distance there could be up to 19x19=361 different area projections. Some examples of such potential correlation areas for 20 km

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separation are presented below.

Figure 5

To provide wide range of results for different separation distances it is easier to present only cell area percent relevant to correlation zone (100% correspond to the circle area defined by cell radii). Set of tables for all combination of interfering and victim cells for separation distances from 12 to 50 km is attached in the Annex 1.

Next step is to look on the impact in terms of propagation. It is likely to have harmful interference at the edge of the cell and unlikely to have any interference near wanted BS. Also the magnitude of the impact is very dependent both on path losses between wanted Tx and victim Rx and path losses between interfering Tx and victim Rx. It is proposed to look at the worst case when path loss between wanted BS and victim Rx is approximated with

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Hata suburban model and pass loss between interfering BS and victim Rx is approximated with Hata rural model. Actual area where correlation causes harmful interference could be defined from pilot signal levels difference and processing gain value. In coordinated case wanted pilot signal should be amplified on processing gain value compared to interfering pilot signal from neighbor cell and at the edge of the cell wanted pilot-to-interfering pilot ratio would be close to 21 dB (Processing gain= 10∙lg(1250/9.6)=21 dB). Therefore it is proposed to define correlation area as area where wanted pilot-to-interfering pilot ratio is lower than 21 dB. All radio parameters were taken from cross border study ECC Report 97. The effect of propagation on correlation area percentage is illustrated below. Colorbar provides grade for wanted pilot-to-interfering pilot ratio, interfered areas are colored in blue tones and non-interfered in red and yellow

tones.Figure 6

The calculation results of correlation area percentage with regard to propagation are presented in Annex 2. Because interference could occur inside the network and not only on the edge the criterion used in cross-border study can’t be applied. The separation distance which corresponds to the threshold is defined as minimum distance when 1% or less of cell area could be interfered by uncoordinated BS.

The analisys in Annex 2 showed that interfered area become lower than 1% with the separation distance between 40 and 42 km. In more detailed analysis it was found that 41 km almost exactly corresponds to 1% of correlation area. The cell correlation area variant for 41 km separation distance is presented below.

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Figure 7

For this distance the threshold level is defined using SEAMCAT, the exact way it was defined in ECC Report 97. To provide permitted level on the boreder 25 kHz band receiver on a height of 3 meters was modeled in SEAMCAT 3 on a distance of 20.5 km from the closest BS in CDMA cluster. The modeled case and the correspond level -107.5 dBm shown on the figure below. Yellow point denotes measuring receiver location on the border and red points denote interfering CDMA BS cluster, blue point have no physical meaning for the study and just obligatory for SEAMCAT simulation.

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This level is 3.5 dB less than level received for coordinated case and proposed to be used as a maximum permitted level for uncoordinated networks. The calculation of relevant field strength level for uncoordinated networks case in 450 MHz band is presented below:

Central frequencyof downlink band

Threshold field strength level

on the border (rounded)*

Overall CDMA BS signal strength on the border**

465 MHz 23 dBuV/m/ 25 kHz 40 dBuV/m/ 1.25 MHzTable 2

* - measured in a bandwidth of 25 kHz at a height of 3 metres in 50% of time.**- measured in a bandwidth of 1250 kHz at a height of 3 metres in 50% of time (recommended).

conclusions

To provide maximum coverage in border areas where concerned Administration using CDMA systems based on CDMA2000 interface with coincident frequency plans to prevent mutual harmful interference it is strongly recommended to use code coordination what leads to higher permitted levels of maximum field strength on the border. The procedure for allocation of preferential and non-preferential codes is provided in this report. 5% or even less of codes should be excluded from border areas to prevent any possibility of correlation between base stations of different Administration.

The threshold level 43.5 dBuV/m is proposed for the case of two coordinated CDMA networks in 450 band using aligned frequencies and preferential codes. For uncoordinated networks and when there is no exact information about CDMA networks frequency plans the level of 40 dBuV/m is proposed. If the network operators on both sides of the border are prepared to accept higher levels of interference than the coordinated level to work closer to the borders with some impact on the loss of service it is even more important to perform code coordination to prevent higher probability of correlation between neighboring networks signals.