Describe radio aspect and security aspects of IS-95 system.

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Radio aspects of IS 95system

Moduation	Quadrature phase shift keying or variations
Channel/Chip rate	1.2288 Mcps
Nominal data rate (Rate Set 1)	9.6 kbps
Filtered bandwidth	1.23 Mhs > 1.25 Mhz with guard band
Coding	Convolutional coding Constraint lenth = 9 Viterbi decoding
Interleaving	With 20 ms span

Security aspect of IS 95

CAVE (cellular authentication and voice encyrption) algorithm is used .
Uses a 64 bit A-key along with ESN and Random number to generate 128 bit shared secret data (SSD) • SSD is divided into two 64 bit blocks – (A for authentication, B for encryption)
Challenge/Response technique for Authentication .
Random number is used to create key for encryption of voice and data

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CSS- Cellular Subscriber Station

BS-Base station

MSC- Mobile switching center

HLR-Home location registers

EIR-Equipment identity register

VLR- Visiting location registers

AC- Authentication center

Mobile Switching Centre- (MSC): The MSC co-ordinates the activities of all the base stations and connects the entire cellular system to the PSTN. A typical MSC handles 100,000 cellular subscribers and 5,000 simultaneous conversations at a time, and accommodates all billing and system maintenance functions as well. Communication between the BS and mobiles is defined by a standard Common Air Interface (CAI) that specifies four different channels.

Base Station-BS- The base station is installed for every cell. It communicates with all the mobile stations existing in its cell. The BS Communicates with the mobile switching center (MSC).

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