Performance of the forward link of a CDMA cellular network

DaSilva, V.M.; Sousa, E.S.; Jovanovic, Vladan

doi:10.1109/isssta.1994.379592

Cited by 8 publications

(6 citation statements)

References 10 publications

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“…In addition, they averaged over the phases of the multipath gains and the fractional chip delays between the multipaths, but not the amplitudes of the multipath gains. DaSilva and Sousa [4] derived similar expressions for the intracell interference power, assuming BPSK modulation with a sinc chip pulse shape. They also averaged over all channelization codes to arrive at their expressions (long scrambling codes were not included in their model).…”

Section: Relevant Literaturementioning

confidence: 97%

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Analysis and results for the orthogonality factor in wcdma downlinks

Mehta

Greenstein

Willis

et al. 2003

IEEE Trans. Wireless Commun.

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The presence of multipath leads to a loss of orthogonality between the signals transmitted simultaneously on a wideband code-division multiple access (WCDMA) downlink. We derive general analytical expressions for the orthogonality factor (OF), which quantifies this loss of orthogonality, as a function of the instantaneous multipath fade realization of the channel. We show that the OF exhibits a significant temporal variation for the three channel profiles suggested in the WCDMA standard, namely, typical urban, rural area, and hilly terrain, which span a wide range of realistic cases. Moreover, its temporal variations and statistics vary significantly from one channel profile to another. Also, while the pulse shape and the number of Rake fingers has only a marginal impact on the OFs statistics, the granularity in setting the finger positions has a considerable impact. The results of the work can be directly used for evaluation of the system performance of WCDMA cellular systems.Index Terms-Code-division multiple access (CDMA), intracell interference, multipath channels, orthogonality factor, Rake receiver.

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Section: Relevant Literaturementioning

confidence: 97%

“…This is because the period of the scrambling code is much larger than that of the channelization code and different channelization codes may be assigned to users at different times. Therefore, we average over the scrambling and channelization codes in our analysis [3], [4].…”

Section: A Receiver Outputmentioning

confidence: 99%

Analysis and results for the orthogonality factor in wcdma downlinks

Mehta

Greenstein

Willis

et al. 2003

IEEE Trans. Wireless Commun.

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“…Assume that and are vectors containing the chip delays and phase shifts of the paths of User . Letting and noting that , the chip statistics generated solely by MAI (conditioned on and ) can be expressed as 1 (23) where the chip statistic is…”

Section: B Distribution Of Mai and Ipimentioning

confidence: 99%

“…Performance analysis of the Rake receiver has also been the subject of many papers (e.g., [11] and [23]- [26]). In [23] and [24], the effect of orthogonality of the spreading sequences on the SNR performance of the Rake receiver is studied.…”

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confidence: 99%

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Performance Analysis of a Linear MMSE Receiver for Bandlimited Random-CDMA Using Quadriphase Spreading Over Multipath Channels

Mirbagheri

Yoon

2004

IEEE Trans. Wireless Commun.

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This paper analyzes the bit-error-rate ( ) performance of a linear minimum mean-square error (LMMSE) receiver for bandlimited direct-sequence code-division multiple-access systems which use quadriphase spreading with aperiodic pseudonoise (PN) sequences. The analysis is based on the improved Gaussian approximation (IGA) with focus on chip pulse shaping. It shows that the IGA reduces to the standard Gaussian approximation (SGA) if 1) random quadriphase spreading is employed, 2) the spreading factor takes moderate to large values, and 3) the chip pulse excess bandwidth (BW) is zero. Hence, the SGA, known for its inaccuracy in low regions of , remains an accurate approximation even when the number of active users in the system is small as long as the aforementioned conditions are met. The analysis holds for either matched or different transmit and receive filters. Consequently, closed form conditional expressions are derived for the coherent selective Rake and the LMMSE receivers and verified with Monte Carlo simulations. Numerical results are presented to illustrate the performance improvement achieved by the LMMSE receiver which, in contrast to the coherent selective Rake receiver, not only suppresses interference when the excess BW of chip pulse is nonzero, but also harnesses the energy of all paths of the desired user. Under the examined scenarios tailored toward current narrowband system settings, the LMMSE receiver achieves 60% gain in capacity over the selective Rake receiver. A third of the gain is due to interference suppression capability of the receiver while the rest is credited to its ability to collect the energy of the desired user diversified to many paths. Future wideband systems will yield an ever larger gain.Index Terms-Bit-error rate, direct-sequence code-division multiple-access (DS-CDMA), Gaussian approximation, long spreading sequences, minimum mean-square error (MMSE), pulse shaping, Rake receiver.

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