On the Hidden Terminal Problem in Multi-rate Ad Hoc Wireless Networks

Abstract

Multi-hop ad hoc wireless networks generally use the IEEE 802.11 Distributed Coordination Function (DCF) MAC protocol, which utilizes the request-to-send/clear-to-send (RTS/CTS) mechanism to prevent the hidden terminal problem. It has been pointed out that the RTS/CTS mechanism cannot completely solve the hidden terminal problem in ad hoc networks because the interference range could exceed the basic rate transmission range. In this paper we provide a worst-case analysis of collision probability induced by the hidden terminal problem in ad hoc networks with multi-rate functionality. We show that the interference caused by the nodes in the area that is not covered by the RTS/CTS is bounded by C′R ^− 4, where C′ is a constant and R is the distance between the two transmitting nodes. The analytic result showed that the interference could shorten the data transmission range up to 30 percent. We then propose a simple multi-rate MAC protocol that could prevent the hidden terminal problem when transmit power control (TPC) is employed.

This work was supported by the Brain Korea 21 Project in 2004 and grant No.R01-2001-00360 from the Korea Science and Engineering Foundation.