Send And Receive Multi-antenna Systems, Anti-jamming Technology

With the increasing of mobile users and the demands which are transforming from the pure voice service to multimedia service, the limited frequency spectrum resources are running short.In the future the transmission rate in wireless multimedia communications will reach 100Mbit/s. So promotion the utilization ratio of frequency spectrum and increasing the channel capacity is becoming a work which offers many challenges. So will it do in the future.It spurs us to develop highly efficient coding,modulation and signal processing techniques to improve the wireless frequency spectrum efficiency.An effective approach to increase the data rate over wireless channels is to use multiple transmit and receive antennae. A MIMO system provides multiple independent transmission channels, thus, under certain conditions, leading to a channel capacity that increases linearly with the number of antenna elements. Space-time coding technique is a coding technique which is applied in MIMO system.It correlates to multiple antennae and signals transmitted in different periods in temporal and spatial domains,which enable the receiver can overcome fading over MIMO channel and reduce error code transmitted. Comparing with the system which does not space-time code, space-time coding can obtain transmit diversity and increase channel capacity without frequency bandwidth loss. It is shown in research that space-time coding is a feasible and effective approach that reaches or be close to channel capacity in MIMO system.MIMO techniques are the key schemes for achieving high data rate and performance in 3G mobile communications and beyond. The wireless channel is usually unreliable, and it mainly suffers from time-varying fading due to multi-path propagation. This is a significant limitation to communication performance. For increasing the capability to suppress directional interference of the MIMO system, this paper researchs a scheme to suppress directional interference for STBC MIMO system based on Beam-forming. Simulation result shows that the scheme is valid to suppress directional strong interference for STBC MIMO system although with some performance loss compared with the ideal case of non-interference.