Key technologies for IMT-advanced mobile communication systems

WINNER is an ambitious research project aiming at identification, development, and assessment of key technologies for IMTAdvanced mobile communication systems. WINNER has devised an OFDMA-based system concept with excellent system-level performance for flexible deployments in a wide variety of operating conditions. The WINNER system provides a significant step forward from current 3G systems. Key innovations integrated into the system concept include flexible spectrum usage and relaying, adaptive advanced antenna schemes and pilot design, close to optimal link adaptation, hierarchical control signaling, and a highly flexible multiple access scheme. The end-to-end performance assessment results demonstrate that the WINNER concept meets the IMTAdvanced requirements.     

System Performance of Transmit Diversity Methods and a Two Fixed-Beam System in WCDMA

Downlink transmit diversity modes for WCDMA together with a two fixed-beam antenna array system are compared relative to the single antenna sectorized system in a radio network simulator. The transmit diversity methods investigated are: space-time transmit diversity and closed-loop mode I transmit diversity. Frequency selective (COST 259) and flat fading channels are considered and their impact to speech-only and data-only services is evaluated. A third service, which highlights the system performance of the various advanced antennas, is also investigated.The results in this investigation point out that the diversity gain in flat fading channels is substantial. In frequency-selective fading, the benefits of fixed beam systems is encouraging, whereas transmit diversity methods (especially Space-Time Transmit Diversity) is unsatisfactory.     

The road to IMT-advanced communication systems: state-of-the- art and innovation areas addressed by the WINNER + project - [topics in radio communications]

Phases I and II of the WINNER project contributed to the development, integration, and assessment of new mobile network techniques from 2004 to 2007. Some of these techniques are now in the 3GPP LTE and IEEE 802.16 (WiMAX) standards, while others are under consideration for LTE-Advanced and 802.16m. The WINNER+ project continues this forwardlooking work for IMT-advanced technologies and their evolution, with a particular focus on 3GPP LTE-Advanced. This article provides an overview of the WINNER system concept and several of its key innovative components.     

SINR estimation and orthogonality factor calculation of DS‐CDMA signals in MIMO channels employing linear transceiver filters

A discrete‐time model of DS‐CDMA signaling using multiple transmit and receive antennas employing linear transceiver filters is derived. For each link, connecting a base‐station to a wireless mobile user, the downlink signal to interference plus noise ratio (SINR) after despreading is derived analytically, and as a by‐product an exact closed‐form solution of the orthogonality factor is obtained. The orthogonality factor is derived for any linear receiver structure that is implemented by a bank of correlators and for any linear combining techniques (such as MRC and MMSE), and for any number of transmit and/or receive antennas that utilize transmit (pre‐RAKE) and receive (post‐RAKE) filtering. The MIMO DS‐CDMA model is derived using a filter representation, and is extended to a vector/matrix formulation that permits a systematic and efficient way of computing the SINR in a radio network simulator. Copyright © 2006 John Wiley & Sons, Ltd.