Pieter Van Rooyen

The Wireless World Research Forum and Future Smart Antenna Technology

The Wireless World Research Forum (WWRF) is a global organization, which was founded in August 2001. Members of the WWRF are typically manufacturers, network operators/service providers, R&D centers, universities and small and medium enterprises. In particular, the WWRF identify and scope research issues relevant to future mobile and wireless communications, including pre-regulatory impact assessments and invite world-wide participation. As such, the Forum provides a global platform for discussion of results, exchange of views to initiate global cooperation towards systems beyond 3G. In particular, smart antenna technology has become one of the most dominant technologies for future wireless systems. This paper gives and overview of the WWRF and smart antenna technologies being developed within the WWRF

Super-orthogonal space-time turbo transmit diversity for CDMA

Studies have shown that transmit and receive diversity employing a combination of multiple transmit-receive antennas (given ideal channel state information (CSI) and independent fading between antenna pairs) will potentially yield maximum achievable system capacity. In this paper, the concept of a layered super-orthogonal turbo transmit diversity (SOTTD) for downlink direct-sequence code-division multiple-access (CDMA) systems is explored. This open-loop transmit diversity technique improves the downlink performance by using a small number of antenna elements at the base station and a single antenna at the handset. In the proposed technique, low-rate super-orthogonal code-spread CDMA is married with code-division transmit diversity (CDTD). At the mobile receiver, space-time (ST) RAKE CDTD processing is combined with iterative turbo code-spread decoding to yield large ST gains. The performance of the SOTTD system is compared with single- and multiantenna turbo-coded (TC) CDTD systems evaluated over a frequency-selective Rayleigh fading channel. The evaluation is done both by means of analysis and computer simulations. The performance results illustrate the superior performance of SOTTD compared to TC CDTD systems over practically the complete useful capacity range of CDMA. It is shown that the performance degradation characteristic of TC CDTD at low system loads (due to the inherent TC error floor) is alleviated by the SOTTD system.