Abstract: The simplicity of uncoordinated wireless access to a wired backbone leads to cheap wireless networks. For example, WLANs based on IEEE 802.11 family utilize random access to channel resources. However, the performance of such networks is poor compared to third generation cellular technologies, which exploit central resource management. The natural question that arises is: How much performance can we obtain by distributed, uncoordinated access to channel resources? Taking an information theoretic viewpoint, I'll formulate the problem of uncoordinated access in terms of the MAC channel with unknown number of users. I will explain new inner and outer bounds to the capacity region allowing for opportunistic codes.