Learning to exploit diversity in wireless systems
Event details
| Date | 22.06.2009 |
| Hour | 14:15 |
| Speaker | Dr Alexandre Proutière, Microsoft Lab, Cambridge, UK |
| Location | |
| Category | Conferences - Seminars |
Opportunistic scheduling is a key mechanism for improving the performance of wireless systems. However, this mechanism requires that transmitters are aware of channel conditions (or CSI, Channel State Information) to the various possible receivers. CSI is not automatically available at the transmitters, rather it has to be acquired. Acquiring CSI consumes resources, and only the remaining resources can be used for actual data transmissions. We explore the resulting trade-off between acquiring CSI and exploiting channel diversity to the various receivers. Specifically, we consider a system consisting of a transmitter and a fixed number of receivers. We first analyze the case where the transmitter cannot adapt its transmission power, and then extend the analysis to allow for power control. We provide an optimal probing / transmission strategy in both saturated and buffered scenarios. In the former case, the transmitter always have packets to send, and in the latter case, an infinite buffer is associated to each receiver, and packets arrive in this buffer according to some stochastic process with fixed intensity. The proposed strategies may be used in a wide class of wireless systems with limited information, such as broadcast systems without a priori knowledge of the CSIs. But it can be also used to solve dynamic spectrum access problems such as those arising in cognitive radio systems, where secondary users can access large parts of the spectrum, but have to discover which portions of the spectrum offer more favorable radio conditions or less interference from primary users.
Dr Proutière's homepage
Practical information
- General public
- Free