Investigations into diversity of A 2x2 MIMO system with the use of an indoor testbed

This paper presents investigations into an indoor 2×2 multiple input multiple output (MIMO) system, whose diversity performance is assessed using a high precision test-bed. In this system, transmitter and receiver are equipped with 180° or 90° 3dB hybrids with their two output ports terminated with co-polar monopole antennas. By feeding a signal to one of the two input ports of the hybrid (while the other input port is matched terminated) different communication channels in a rich-scattering environment can be created. The test-bed allows for the signal strength measurements around the receiver/ transmitter sides for a given feeding configuration of hybrids when the receiver is moved over a circular region in an indoor environment. The signal strengths maps obtained for various modes of this 2×2 MIMO system are foundations for investigating transmit/receive diversity schemes. As the signal strength measurement results are obtained with Bluetooth modules operating in the ISM 2.4 GHz, the results are of importance to many other wireless systems that aim at utilizing MIMO diversity schemes to enhance their performance in this frequency band.

Assessing an FPGA implemented MIMO testbed with the use of channel emulator

In this paper, a channel emulator for assessing the performance of MIMO testbed implemented in a field programmable gate array technology is described. The FPGA based MIMO system includes a signal generator, modulation/demodulation and space time coding/decoding modules. The emulator uses information about a wireless channel from computer simulations or actual measurements. In simulations, a single bounce scattering model for an indoor environment is applied. The generated data is stored in the FPGA board. The tests are performed for a 2times2 MIMO system that uses Alamouti scheme for space coding/decoding. The performed tests show proper operation of the FPGA implemented MIMO testbed. Good agreement between the results using measured and simulated channel data is obtained.

Design of MIMO testbed with an FPGA board for fast signal processing

This paper describes the design of a Multiple Input Multiple Output testbed for assessing various MIMO transmission schemes in rich scattering indoor environments. In the undertaken design, a Field Programmable Gate Array (FPGA) board is used for fast processing of Intermediate Frequency signals. At the present stage, the testbed performance is assessed when the channel emulator between transmitter and receiver modules is introduced. Here, the results are presented for the case when a 2x2 Alamouti scheme for space time coding/decoding at transmitter and receiver is used. Various programming details of the FPGA board along with the obtained simulation results are reported