In this work, we revisit classical packet radio networks with a modern treatment of physical-layer (PHY) procedures, medium-access (MAC) and geographic channel-driven routing protocols. Our network model assumes that nodes are randomly distributed on the plane according to a homogeneous spatial Poisson process, using which we provide a novel representation of interference statistics resulting from packet collisions. Using this representation, we develop a cross-layer analysis methodology which allows multi-hop routing protocols to be treated using generic information-theoretic models for the underlying PHY/MAC procedures. These models inherently characterize modern procedures such as channel code rate adaptation, incremental redundancy and packet combining/capture. These models further allow for the assessment of the tradeoff between spatial throughput, measured in bit-meters per signal-space dimension, the range of each transmission and the average transmission delay. A generic formulation based on system parameters, such as system bandwidth, propagation models, etc., is given to analyze this tradeoff in an operational setting which can be used to build system simulators for such networks. Finally, from a purely PHY perspective, the results of this work show that coding and incremental retransmission provide a means for reliable communication coupled with a completely decentralized multiple-access strategy.

In this correspondence, we present an efficient protocol for the delay-limited fading ARQ single relay half-duplex channel. The source is using an Automatic Retransmission reQuest (ARQ) retransmission protocol to send data to the relay and the destination. When the relay is able to decode, both the relay and the source send the same data to the destination providing additional gains. The proposed protocol exploits two kinds of diversity: 1) space diversity available through the cooperative (relay) terminal, which retransmits the source's signals and 2) ARQ diversity obtained by leveraging the retransmission delay to enhance the reliability. The performance characterization is in terms of the achievable diversity, multiplexing gain and delay tradeoff for a high signal-to-noise ratio (SNR) regime. Finally, we show the benefits of power control on the diversity by controlling the source's power level over the retransmission rounds.

In this article we propose a set of necessary and sufficient conditions under which the long-term averaged throughput in an ad hoc network can remain constant as the number of nodes n increases. Throughput refers to the minimum achievable rate between a source-destination pair for a given routing mechanism and physical model, when the network is shared by Θ( n ) randomly chosen source-destination pairs. The main idea is to use a connectivity graph , which does not represent the actual physical network but rather the available communication resources. This graph also allows one to translate the problem of maximizing the throughput in ad hoc networks to the multicommodity flow problem and directly apply related results.

In this paper, we present an efficient protocol for the delay-limited fading automatic retransmission request single relay channel. The source is using an ARQ retransmission protocol to send data to the relay and the destination. When the relay is able to decode, both the relay and the source send the same data to the destination providing additional gains. The proposed protocol exploits two kinds of diversity: (i) space diversity available through the cooperative (relay) terminal, which retransmits the source's signals, (ii) ARQ diversity obtained by leveraging the retransmission delay to enhance the reliability. The performance characterization is in terms of the achievable diversity, multiplexing gain and delay tradeoff for a high signal-to-noise ratio (snr) regime

We establish lower bounds on the capacity of wireless ad hoc networks with two types of non-uniform traffic patterns. We first focus on the impact of traffic patterns where local communication predominates and show the improvement in terms of per user-capacity over ad hoc networks with unbounded average communication distances. We then study the capacity of hybrid wireless networks, where long-distance relaying is performed by a fixed overlay network of base stations. We investigate the scaling of capacity versus the number of nodes and the density of base stations in the area of the network. The throughput capacity results under these two scenarios hold with probability one as the number of nodes goes to infinity.