Gerald Lehmann

Performance of smart antenna in TD-SCDMA system

Smart antenna technology is one of key technologies used in the TD-SCDMA system. By using DSP algorithms and dynamically generating the beam patterns, a smart antenna can greatly reduce the interference and increase the system capacity. The concept of smart antenna is presented and a novel detection technique called joint space-time processing based on the smart antenna is described. Simulation results on the uplink performance of TD-SCDMA in a macrocellular environment are also included. It can be seen that the smart antenna system has much better performance than a system without a smart antenna and can meet the requirements of the third-generation systems.

Evaluation of link-level performance improvements by using smart antennas for the TD-CDMA based UTRA TDD mobile radio system

For third generation mobile radio systems like the TD-CDMA based UTRA TDD mode the use of smart antenna technology promises a substantial performance improvement on the up- and the downlink. The third generation mobile radio system UTRA with the TDD mode, which utilizes a combined CDMA and TDMA multiple access scheme, has been specified in the Third Generation Partnership Project (3GPP). The use of smart antennas at the base station reduces interference in two ways: on the uplink the intercell interference can be suppressed. The estimated spatial information about the users and interferers can then be used for beamforming on the downlink, which significantly reduces the interference also in this direction. Especially for terminals with a RAKE-receiver-structure a major performance improvement can be observed because of the intracell interference reduction. These performance improvements are expressed in concrete results derived from link-level simulations using the described technology and simulation environment.

Real-Time Demonstration of Mobile Broadcasting Services via MBMS

MBMS (Multimedia Broadcast/Multicast Service) is a unidirectional point-to-multipoint (p-t-m) service which allows to transmit data from a single source entity to a group of mobile users in a certain coverage region. In order to investigate the performance of this IP datacast (IPDC) type of services over packet-switched cellular networks like UMTS or GPRS, a real-time MBMS system demonstrator has been developed jointly by Nomor Research, Siemens Networks GmbH, and Siemens AG. The unique setup covers most of the functionalities specified for the various MBMS network elements, as well as realistic channel models for the specified MBMS bearers. In addition, several advanced features are supported, including Application Layer Forward Error Correction (AL-FEC), system-internal switching between p-t-p and p-t-m radio bearers, and user-defined selection of different media services during operation. The whole setup is complemented by a streaming server and multiple PDA clients connected via IP to the simulator. Hence, realistic multimedia content can be broadcasted via the simulator in real-time, and the received quality at different mobile terminals can be visualized immediately for different system parameter settings and media contents. Besides its live demonstration capabilities, the presented platform can also be used as a valuable tool in research and development.