We analyze the two-user single-antenna fading interference channel with perfect receive channel state information (CSI) and no transmit CSI. The diversity-multiplexing tradeoff (DMT) region of a fixed-power-split Han and Kobayashi (HK)-type superposition coding scheme is considered and design criteria for the corresponding superposition codes are derived. We demonstrate that this scheme is DMT optimal under strong and very strong interference by showing that it achieves a DMT region outer bound that we derive. !n addition, we show that, under very strong interference, decoding interference while treating the intended signal as noise, subtracting the result out, and then decoding the desired signal, a process known as “stripping”, achieves the optimal DMT region. Our proofs reveal code design criteria for achieving DMT optimality (in the cases where we can demonstrate it).

We analyze two-user single-antenna fading interference channels with perfect receive channel state information (CSI) and no transmit CSI. For the case of very strong interference, we prove that decoding interference while treating the intended signal as noise, subtracting the result out, and then decoding the desired signal, a process known as ldquostrippingrdquo, achieves the diversity-multiplexing tradeoff (DMT) outer bound derived in Akuiyibo and Leveque, Int. Zurich Seminar on Commun., 2008. The proof is constructive in the sense that it provides corresponding code design criteria for DMT optimality. For general interference levels, we compute the DMT of a fixed-power-split Han and Kobayashi type superposition coding scheme, provide design criteria for the corresponding superposition codes, and find that this scheme is DMT-optimal for certain multiplexing rates.

We analyze fading relay networks, where a single-antenna source-destination terminal pair communicates through a set of half-duplex single-antenna relays using a two-hop protocol with linear processing at the relay level. A family of relaying schemes is presented which achieves the entire optimal diversity-multiplexing (DM) tradeoff curve. As a byproduct of our analysis, it follows that delay diversity and phase-rolling at the relay level are optimal with respect to the entire DM-tradeoff curve, provided the delays and the modulation frequencies, respectively, are chosen appropriately.

Routing data through a wireless network is made challenging by impairments in the wireless medium, such as fading. Nevertheless, wireless routing if implemented, will result in tremendous cost-savings in next generation wireless networks. This paper examines centralized and decentralized approaches for wireless routing from a PHY/MAC perspective. We show that decentralized routing strategies are capable of realizing full spatial diversity gain if an appropriate level of channel knowledge is available at the relay terminals. Furthermore, we propose a new carrier sensing random access based routing technique designed to avoid collision and conserve network power. A numerical example is provided to demonstrate that the technique is capable of realizing full spatial diversity gain.