Collision　avoidance　and　spatial　reuse　are　two　important　approaches　to　improving　the　throughput　of　ad　hoc　networks,　and　many　MAC　protocols　are　proposed　to　achieve　these　goals.　In　most　MAC　protocols,　collisions　are　reduced　by　solving　the　hidden　terminal　problems,　but　the　spatial　reuse　remains　un-optimized　in　these　protocols,　which　affects　network　throughput　dramatically.　Moreover,　reception　of　exposed　terminals　is　not　allowed　in　current　MAC　protocols　even　if　they　can　receive　packets　successfully,　which　leads　to　lower　spatial　reuse.　In　this　paper,　a　high　throughput　MAC　protocol　named　e-MAC　is　proposed.　To　improve　the　network　throughput,　two　approaches　are　used　in　e-MAC.　First,　a　power　controlled　busy　tone　is　used　to　eliminate　hidden　terminals.　The　receiver　adjusts　the　transmission　power　of　busy　tone,　according　to　a　received　signal　strength　from　the　transmitter,　so　that　the　spatial　reused　is　optimized　while　all　hidden　terminals　are　covered　by　a　busy　tone.　Second,　exposed　terminals　are　allowed　to　receive　when　the　ratio　between　signal　strength　of　RTS　(ready-to-send)　and　interference　satisfies　the　SINR　(signal　to　interference　and　noise　ratio)　requirements,　which　further　improves　the　spatial　reuse.　Simulation　results　show　that　the　average　throughput　of　e-MAC　outperforms　that　of　DUCHA　(dual　channel　access)　by　87%.　©　by　Institute　of　Software,　the　Chinese　Academy　of　Sciences.