Showing papers by "Geoffrey G. Messier published in 2006"
TL;DR: An STTD CDMA forward link simulation shows that link performance is significantly improved when the mobile turbo decoder uses the more accurate CSI provided by improved estimation, but the degree of improvement depends on the turbo decoding algorithm, mobile velocity, and whether the base station is using STTD or single-antenna transmission.
Abstract: This paper proposes an approach to improve turbo code performance on the space time transmit diversity (STTD) code-division multiple-access (CDMA) forward link through better estimation of the channel state information (CSI) required by the mobile turbo decoder. An improved CSI estimation scheme that accounts for the unique nature of CDMA STTD intracell interference is presented. It is compared to a standard CSI estimation scheme that assumes all STTD interference and noise can be represented as additive white Gaussian noise at the mobile receiver input. An STTD CDMA forward link simulation shows that link performance is significantly improved when the mobile turbo decoder uses the more accurate CSI provided by improved estimation. However, the degree of improvement depends on the turbo decoding algorithm, mobile velocity, and whether the base station is using STTD or single-antenna transmission
5 citations
TL;DR: In this paper, a new code-division multiple access (CDMA) system architecture that combines space-time block code (STBC) transmission and adaptive sectorization using electronically tunable reflectarrays is presented.
Abstract: This letter presents a new code-division multiple-access (CDMA) system architecture that combines space-time block code (STBC) transmission and adaptive sectorization using electronically tunable reflectarrays. The result is a single base station architecture that can use a combination of diversity and spatial division transmission in order to achieve good performance in a wide range of environments. The reflectarray method has the further advantage of implementing both STBC and adaptive sectorization using a single transmit chain and power amplifier. This significantly reduces the cost of deploying a multiple antenna scheme and makes it possible to retrofit combined STBC/adaptive sectorization transmission to existing single antenna base stations already in the field.
4 citations
TL;DR: Logfile data from commercial code division multiple access networks are used to quantify the base station power amplifier (PA) size reduction achieved with sector transmit power pooling and indicate that sector power pooled can significantly reduce required PA size for realistic network operating conditions.
Abstract: This paper uses logfile data from commercial code division multiple access networks to quantify the base station power amplifier (PA) size reduction achieved with sector transmit power pooling. Sector transmit power pooling in a base station involves sharing the transmit power load of several sectors across the same bank of amplifiers. This transmit power trunking results in a reduction in required PA size. The logfile analysis used to estimate this reduction is augmented with simulated short-term power variations. A new constrained Poisson call arrival model is used to ensure that the simulated power variations accurately reflect actual network operating conditions. A Gamma random variable approximation is also used to improve simulation efficiency. The results of this analysis indicate that sector power pooling can significantly reduce required PA size for realistic network operating conditions
TL;DR: The results indicate that the channel state estimation scheme that provides the best forward link performance depends on the type of channel code and channel decoder algorithm used in the system.
Abstract: This paper investigates how to improve channel decoder trellis path metric calculations when convolutional or turbo codes are combined with the chip-level linear minimum mean square error (LMMSE) code division multiple access (CDMA) mobile receiver. These metric calculations require channel state information (CSI) that consists of desired signal amplitude and interference plus noise variance. Several techniques suitable for use with the chip-level LMMSE receiver are presented for estimating CSI. Chip-level simulations are used to evaluate CDMA forward link performance when these techniques are used by the mobile. The results indicate that the channel state estimation scheme that provides the best forward link performance depends on the type of channel code and channel decoder algorithm used in the system.