Deepshikha Garg

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A very high-speed wireless access of 100Mbps to 1Gbps is required for the 4th generation (4G) mobile communications systems. However, for such high-speed data transmissions the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel(More)
SUMMARY OFDM, MC-CDMA and DS-CDMA are being researched vigorously as the prospective signaling technique for the next generation mobile communications systems, which will be characterized by the broad-band packet technology. With packet transmissions, hybrid ARQ (HARQ) will be inevitable for error control. HARQ with rate compatible punctured turbo (RCPT)(More)
—The next-generation mobile communications system is anticipated to support very high-speed data rates exceeding several tens megabits per second. In this paper, we consider high-speed downlink packet access for direct-sequence code-division multiple access (DS-CDMA) as in third–generation wideband code-division multiple-access systems. Adaptive modulation(More)
In MC-CDMA, the data rate can be increased by reducing the spreading factor SF or by allowing multicode transmission. In this paper, we evaluate by computer simulations which gives a better bit error rate (BER) performance lower SF or multicode operation-when high level modulation is used in addition to error control coding. For a coded system in a(More)
— Iterative adaptive soft parallel interference canceller (ASPIC) is proposed for turbo coded multiple-input multiple-output (MIMO) multiplexing. ASPIC is applied to transform a MIMO channel into single-input multiple-output (SIMO) channels for maximum ratio diversity combining (MRC). In the iterative ASPIC, replicas of the interference from different(More)
SUMMARY Very high-speed data services are demanded in the next generation wireless systems. However, the available bandwidth is limited. The use of multi-input multi-output (MIMO) multiplexing can increase the transmission rate without bandwidth expansion. For high-speed data transmission , however, the channel becomes severely frequency-selective and the(More)
In this paper, we present a comprehensive performance evaluation of chip interleaving effect on turbo coded direct sequence spread spectrum (DS-SS) system in a frequency non-selective Rayleigh fading channel with antenna diversity reception. At the transmitter, chip interleaver scrambles the SF (spreading factor) chips associated with a data symbol and(More)
SUMMARY In downlink MC-CDMA, orthogonal variable spreading factor (OVSF) codes can be used to allow multirate communications while maintaining the orthogonality among the users with different data rates. In this paper, we point out that simple selection of the OVSF codes results in degraded performance. We show that this happens because simple code(More)
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