CDMA_System_Analysis - TLEN 5320 Experiment 14 CDMA System...

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1 TLEN 5320 Experiment 14 CDMA System Analysis II Authors: Timothy X Brown, Silvana Susi, Sukhjinder Singh University Of Colorado, Boulder Purpose This experiment allows the student to gain a meaningful understanding of the IS-95 system specifications by observing the relationship between the different group categories of the PN Offset: Active Set, Candidate Set, and Neighbor Set, and the Layer 3 messages between the mobile and the base station while the terminal is active in the system. Equipment - RSAT-2000 CDMA/AMPS equipment - A Portable Computer or desktop with OptimEyes Software Introduction IS-95 Interim Standard 95 (IS-95) is a U.S. digital cellular system based on CDMA that allows each user within a cell and in adjacent cells to use the same radio channel. Each IS-95 channel occupies 1.23MHz of spectrum in each one-way link, which corresponds to 41 30kHz AMPS channels. 1 The user data is spread to a channel chip rate of 1.2288MHz. IS-95 uses a different modulation and spreading technique for the forward and reverse links. On the forward link, the base station simultaneously transmits the user data for all mobiles in the cell by using different spreading sequence for each mobile. The user data is encoded, interleaved, and spread by one of sixty- four orthogonal spreading sequences (Walsh functions). To avoid interference, all signals in a particular cell are scrambled using a pseudorandom sequence of length 2 15 chips. 2 CDMA base stations transmit information in four logical channel formats: pilot channels, sync channels, paging channels, and traffic channels.
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2 TLEN 5320 Experiment 14 At both the base station and the terminal, Rake receivers are used to resolve and combine multipath components, in order to improve the link quality. In IS- 95, a three-finger Rake receiver is used at the base station. 4 IS-95 Logical Channels Pilot Channel: is used by the base station to provide a reference for all mobile stations. It provides a phase reference for coherent demodulation at
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This note was uploaded on 08/08/2011 for the course CS 310 taught by Professor Aartisingh during the Spring '11 term at National Institute of Technology, Calicut.

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CDMA_System_Analysis - TLEN 5320 Experiment 14 CDMA System...

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