In wireless communications, the channel conditions vary over time due to signal fading and multipath propagation. If a wireless device can transmit simultaneously over different channels, there is a chance that some of these channels may have better conditions than others; therefore the overall performance will improve. The widely known Multiple Input-Multiple Output (MIMO) technology works on this principle. While MIMO provides spatial diversity through multiple antennas on the same wireless device, user cooperation does so through a partner's antenna. This means that spatial diversity can be obtained in small size wireless devices which cannot have more than one antennas. The idea behind cooperation is, when a wireless device transmits signal, the signal is "overheard" by another wireless device (the partner). If the partner also sends a copy of that signal to the destination, spatial diversity is achieved.
In order for cooperative diversity to benefit a particular application, such as wireless video, there are many questions to be answered. For example:
In this project we are interested in answering the above questions both from an information theoretic perspective and also for practical source and channel coders. In particular, we investigate real-time multimedia communications over wireless. We will include video simulations and channel simulations while jointly optimizing parameters at both layers. We will gather performance measures from simulation to determine how cooperation can benefit wireless multimedia communications.
This research is partially funded by NSF, Philips, WICAT, CATT.