Power control versus multiuser detection based cross-layer design in wireless ad hoc networks

In wireless ad hoc networks, multiple access interference is the limiting factor for the overall system performance. The lack of any central control unit necessitates a careful joint design of both, the physical and the MAC layer. Two promising technologies that address this problem are power control based cross-layer design and multiuser detection based cross-layer design. While approaches in the first category suppress the interference by power control at the transmitter side, approaches in the second cancel interference at the receiver with a technique called multiuser detection. In this paper, we compare two cross-layer approaches that are representative of power control based cross-layer design and multiuser detection based cross-layer design, respectively. We separately investigate both, the solely PHY performance of the proposed solutions, and the gains achieved by the appropriate MAC design, in terms of overall throughput. Thus, we gain insight into the interaction between both layers that reflects the quality of the cross-layer designs. We test the performance in medium as well as high traffic load scenarios. Based on the obtained results, we show that applying power control in cross-layer designs can in dense traffic scenarios even lead to a worse performance than no cross-layer design at all. Thus, we conclude that in general MUD-based cross-layer design is the better alternative.