Transmission Capacity of Wireless Ad Hoc Networks With Successive Interference Cancellation

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> The transmission capacity (TC) of a wireless <emphasis emphasistype="boldital">ad hoc</emphasis> network is defined as the maximum spatial intensity of successful transmissions such that the outage probability does not exceed some specified threshold. This work studies the improvement in TC obtainable with successive interference cancellation (SIC), an important receiver technique that has been shown to achieve the capacity of several classes of multiuser channels, but has not been carefully evaluated in the context of <emphasis emphasistype="boldital">ad hoc</emphasis> wireless networks. This paper develops closed-form upper bounds and easily computable lower bounds for the TC of <emphasis emphasistype="boldital">ad hoc</emphasis> networks with SIC receivers, for both perfect and imperfect SIC. The analysis applies to any multiuser receiver that cancels the <emphasis><formula formulatype="inline"><tex>$K$</tex></formula></emphasis> strongest interfering signals by a factor <emphasis><formula formulatype="inline"><tex>$z \in [0,1]$</tex> </formula></emphasis>. In addition to providing the first closed-form capacity results for SIC in <emphasis emphasistype="boldital">ad hoc</emphasis> networks, design-relevant insights are made possible. In particular, it is shown that SIC should be used with direct sequence spread spectrum. Also, any imperfections in the interference cancellation rapidly degrade its usefulness. More encouragingly, only a few—often just one—interfering nodes need to be canceled in order to get the vast majority of the available performance gain. </para>