The deterioration of the error performance in mobile radio, such as the pan-European personal communications network (PCN) termed Digital Cellular System (DCS) 1800, due to time variant multipath propagation can be reduced by using diversity techniques. The application of coherent receiver antenna diversity (CRAD) is especially attractive because the parameters of an established mobile radio system remain unchanged. In this communication, the benefits of CRAD in DCS 1800 full rate speech transmission are considered. In order to fully exploit the benefits of CRAD, a soft output Viterbi detector with CRAD (CRAD-SOVD) tailored to predetection maximal-ratio combining (MRC) is applied at the receiver. Both the uncoded and coded bit error rate as well as frame error rate performance determined in extensive simulations of typical urban environments are presented. It is demonstrated that considerable signal-to-noise ratio improvements of /spl ap/6.3 dB@BER=10/sup -2/ at the output of the CRAD-SOVD, /spl ap/5.5 dB@BER=10/sup -3/ at the output of the convolutional decoder, /spl ap/4.7 dB@FER=10/sup -2/ at the output of the convolutional decoder, and /spl ap/4.8 dB@FER=10/sup -2/ at the output of the block decoder are obtainable by using two receiver antennas. These signal-to-noise ratio improvements are especially important with respect to close proximity operation in a multioperator environment which is likely to be established in DCS 1800.

The use of coherent receiver antenna diversity (CRAD) in combination with powerful channel coding is advisable in order to obtain sufficient quality in digital mobile radio systems. The application of both CRAD and a novel convolutional code termed the turbo-code to the uplink of a joint detection (JD) code division multiple access (CDMA) mobile radio system is considered. New results on the coded error performance obtained by using the well-known powerful JD techniques zero forcing block decision feedback equalization, minimum mean square error block linear equalization, and minimum mean square error block decision feedback equalization, which were extended to CRAD with maximal-ratio combining, are presented when either one or two receiver antennas are applied. Both bit and frame error rates, respectively, are introduced and compared with formerly published results. The performance enhancement is demonstrated. Furthermore, it is shown that there is a linear dependence between the bit as well as frame error rate and the variance of the log-likelihood ratios generated by the turbo-code decoder. Therefore, the turbo-code decoder can provide information about the current system performance by estimating the variance of the log-likelihood ratios.

In order to guarantee communication links of sufficient quality, channel coding is required in mobile radio systems. A novel class of binary parallel concatenated recursive systematic convolutional codes termed turbo-codes allowing a near Shannon limit performance without affecting the data rate was proposed and investigated for additive white Gaussian noise channels. Using a simple turbo-code based on a 16-state recursive systematic convolutional code, the authors demonstrate the applicability of turbo-codes to a CDMA mobile radio system using joint detection and coherent receiver antenna diversity. The considered turbo-code is tailored to the delay requirements of voice communications. Furthermore, the performance advantage of this turbo-code over a regular convolutional code is demonstrated.>

For future mobile radio systems, an appropriately chosen multiple access technique is a critical issue. Multiple access techniques presently under discussion are code division multiple access (CDMA), time division multiple access (TDMA), and hybrids of both. In the paper, a hybrid C/TDMA system using joint detection (JD-C/TDMA) with coherent receiver antenna diversity (CRAD) at the base station (BS) receiver is proposed. Some attractive features of the JD-C/TDMA system are the possibility to flexibly offer voice and data services with different bit rates, soft capacity, inherent frequency and interferer diversity, and high system capacity due to JD. Furthermore, due to JD, a cluster size equal to 1 can be realized without needing soft handover. The single cell E/sub b//N/sub 0/ performance and the interference situation in a cellular environment of the uplink of a JD-C/TDMA mobile radio system with CRAD is investigated in detail. It is shown that the cellular spectrum efficiency is remarkably high, taking values up to 0.2 bit/s/Hz/BS in the uplink, depending on the actual transmission conditions.>