RTC/CTS

Keep in mind, though, that an increase in performance using RTS/CTS is the net result of introducing overhead (i.e., RTS/CTS frames) and reducing overhead (i.e., fewer retransmissions). If you don't have any hidden nodes, then the use of RTS/CTS will only increase the amount of overhead, which reduces throughput. A slight hidden node problem may also result in performance degradation if you implement RTS/CTS. In this case, the additional RTS/CTS frames cost more in terms of overhead than what you gain by reducing retransmissions. Thus, be careful when implementing RTS/CTS.

Reference: http://www.wi-fiplanet.com/tutorials/article.php/1445641