IEEE 802.11e optionally adopts the direct link setup to achieve efficient transmission. With a direct link, bandwidth utilisation can be significantly increased by an appropriate transmission order. Presented is an algorithm, called Eulerian transmission order (ETO), that constructs an optimal transmission order for direct links. It is proved that it requires minimal transmission cost. Also presented is the corresponding medium access control scheme called Eulerian co-ordinated channel access. Through simulations, transmission costs for ETO, random order, greedy order and without direct link are compared.