Traditional perspectives derived from wired networks treat each user as an individual and are subject to a layered architecture which is unnecessarily restrictive as it ignores two key characteristics of wireless medium: broadcast nature and spatial diversity. Inspired by the recent idea of cooperative communication, it is realised that intelligent cooperation among nodes may significantly improve network performance by exploiting the above physical characteristics. The popular IEEE 802.11 protocol has been widely deployed in public due to its simple but effective distributed contention-based access mechanism. It is essential to incorporate cooperation into contention-based networks to exploit the benefits of cooperation while keeping the effectiveness of the contention-based access mechanism.