Setup photo

Introduction
This project supported Philips Research in validation of new algorithms for WLAN MIMO systems. A simulation environment and test-bed were developed and some of the validated algorithms are currently being proposed for inclusion in the IEEE 802.11n standard. This project was executed on site, this allowed close cooperation between the project team and the customer. It ran over 18 months with a total effort of 5 FTE.

Problem description
The IEEE 802.11a/g WLAN standards are widely used and are based on OFDM modulation in the 2.4 or 5.x GHz band. With multiple antennas (so called MIMO systems) a better link performance can be obtained. Different methods can be applied, such as simple antenna selection algorithms, or more complicated methods with more signal processing. To validate these algorithms a test environment was developed and realised.

Project results
The project followed two main tracks. The first track resulted in a flexible simulation environment. The latter led to an offline test-bed that proofs the concept of the MIMO principle in real-life wireless environment. Both of these systems enable a good comparison of existing and new algorithms. The systems were designed to be as close as possible to the existing IEEE 802.11a standard but also to provide sufficient flexibility to support the standardisation committee of Philips Research.

Simulations environment
A high-level system description was developed in software, which enabled the evaluation of receiver algorithms and transmission strategies in both theoretically perfect and in more practical circumstances. Several channel models; synchronisation algorithms and RF impairments were modelled.

Results of simulations

Offline Test-bed
The test-bed hardware supported realistic through the air transmission with up to four transmitters and receivers at 5.x GHz. Digital signal processing included encoding/decoding and synchronisation and was handled off-line in a PC running MatLab. The realised transmitter and receiver had a RF specification comparable or better to existing RF chipsets in the market. This test- bed can provide a good starting point for the development of an IEEE 802.11n Chip set. Depending on the transmission channel, the test-bed reliably decodes packets transmitted off air, using modulation and coding corresponding to more then 216 Mbit/sec.

Block diagram of the receiver

System definition, partitioning and implementation
1.System definition:
The project started with a study on the underlying space time coding principles. In parallel we identified already available hardware and signal processing algorithms. All available information is put together in order to create a complete system overview. During this process we identified missing and critical functional blocks.
2.System partitioning:
After that the system was partitioned in different system functionalities and mapped onto different implementation methods. This process was guided by the project goals, results of the study phase and the implementation restrictions. The final result was the system partitioning and formed a basis for hardware and software specifications.
3.System implementation:
Both design and integration of hardware and software components was done in the project team. Part of the implementation was executed on-site the rest was outsourced to other workshops.

Matlab based demonstrator interface.

Demonstrations
TUE Broadband at your hand 2005
Philips Conference on Digital Signal Processing 2006.