Amir Aminzadeh Gohari

Challenges: automated design of networking protocols

This paper establishes a framework for the automated generation of networking protocols. The need for the rapid design of networking protocols in application-specific contexts has increased dramatically over the past five years. Each new application requires high performance in its own domain, as well as a rapid design cycle. Further, changes in physical layer technology quickly render previously high-performance protocols poor performance. Currently, there are no tools to automate the design of networking protocols. This paper addresses the challenge of building such tools. It proposes a methodology and a design chain for the automated generation of networking protocols, with the following novel ideas: (1) Formulation of the network protocol problem such that the exchange of protocol control information can be specified as part of the optimization program, (2) Optimal waveform generation, which specifies the optimal exchange of both control information and data, (3) Protocol Extraction: The extraction of the optimal protocol as a minimal description of the optimal waveforms. This methodology has the potential to dramatically change the future of networking protocol design by moving protocol design to a more abstract level, finding high-performance protocols not easily discovered by human intuition, and reducing the currently long protocol design cycles.

RMR: Reliability based multi-hop routing in wireless tactical networks

We propose a novel routing protocol, RMR, for wireless tactical, high-mobility military networks that finds reliable routes through difficult terrains with possibly compromised regions. RMR uses an end-to-end reliability measure that includes both end-to-end connectivity as well as trustworthiness, and reactively discovers routes over spatial cells whose local reliability is proactively maintained by fast dissemination through the network. By using a space-centric approach where reliability is attributed to space rather than to nodes, RMR is able to find reliable routes through space that persist for longer durations than node-centric protocols. Via QualNet simulation studies, we compare the performance of our protocol with AODV in terms of end-to-end reliability as well as delay, and packet delivery ratio (PDR), and quantify the effects of node density, velocity, and traffic load on these performance metrics.

Towards automated design of MAC protocols for underwater wireless networks

We present a framework for the automated design of MAC protocols for underwater acoustic wireless networks. We formulate a protocol optimization problem in which the exchange of control packets is explicitly modeled. A protocol optimization program generates the optimal response functions to the reception of control packets. In a single MAC neighborhood, each node is modeled as having a behavioral model of the rest of the nodes in the network, where the node behavior is to be optimized. In this framework, we solve the problem of minimizing the average energy consumption of a network subject to a per-node minimum throughput constraint. Our results display the optimal responses for the scheduling of control and data packets for all of the nodes. This work serves as a starting point for the design of automation tools for MAC protocols in the future.

DMQR: A spatial routing protocol to enable VoIP over high-mobility wireless multihop networks

We develop a space-centric routing protocol to enable the delivery of mobile VoIP over high-mobility multi-hop wireless networks. The novel aspect of this protocol is the attribution of network and MAC layer congestion to space, which provides delay guarantees over much longer durations than can be achieved by node-centric routing protocols. The presented protocol constructs a spatial map of network congestion and utilizes this map to reactively find routes over space (cells) rather than individual nodes. The amount of congestion in each cell is tracked proactively by measurements of experienced local delay and is quickly disseminated among the nodes. Through QualNet simulations, we demonstrate substantial improvements in comparison with AODV and LAR over a realistic terrain with obstacles, for a wide range of node densities and velocities.

TraJECT-3D: Generating realistic mobility traces for tactical network simulation

We present TraJECT-3D (Track and Junction based Exploit over Complex Terrain), a realistic generator of node movement trajectories for simulating tactical Mobile Ad-Hoc Networks (MANETs). TraJECT-3D models the macro- and micro-mobility of different types of tactical nodes (e.g., soldiers, scouts, vehicles, UAVs) with a bidirectional track and junction strategy. The novel aspects and distinguishing features of our mobility model are: (1) supporting a three dimensional topology which is essential for realistic modeling of tactical scenarios in difficult terrains, and (2) considering variable size group mobility, multiple mission-based formations, and the inclusion of aerial traffic at the macro-mobility level and correlated movements at the micro-mobility. TraJECT-3D is validated by illustrating how the interactions between terrain characteristics, macro-mobility and micro-mobility models reproduce typical phenomena of tactical networks. Evaluation results show that the choice of mobility model heavily impacts node movement and density over terrain which in turn has a large impact on the performance of networking protocols.

Reliability-aware geocast for mobile ad hoc networks

We present a geocast protocol for mobile ad hoc networks that selects the most statistically reliable path towards the geocast region. The novel aspect of our protocol is the attribution of network layer reliability to space, which enables reliability-aware geocast and provides soft delay guarantees. The proposed approach focuses on route reliability as the end-to-end metric and constructs a map of local reliabilities on the deployment region. We show that the end-to-end reliability of a geographic route is written as a product of the local reliability estimates along the path from the source to the destination. The geocast protocol of this paper exploits this characteristic and discovers geographic routes that pass through the most statistically reliable regions. We evaluate the performance of the geocast protocol in terms of packet delivery ratio and delay, and quantify the effect of node density, velocity, and traffic load on these performance metrics. The simulation results indicate that a high packet delivery rate and an acceptable latency are achieved for a wide range of node densities and velocities.

Congestion-Aware Spatial Routing in Hybrid High-Mobility Wireless Multihop Networks

We develop a spatial framework to provide end-to-end delay estimates and guarantees in mobile multihop networks. The novel aspect of this approach is the attribution of network and MAC layer congestion to space, which enables congestion-aware routing and provides delay guarantees over a much longer duration than that achieved by the routing algorithms based on individual nodes. In a mathematically rigorous setting, first, we prove that over the duration during which the node density and the traffic pattern remain stationary, the expected values of local congestion and end-to-end delay roughly remain invariant. Second, we present an accurate method of delay estimation over geographic paths, namely path integration, and derive an upper bound for its estimation error. Further, we develop a congestion-aware routing protocol that utilizes the spatial maps of network congestion to enable delay-optimized routing of real-time applications. Through extensive QualNet simulations, we perform a detailed evaluation of the presented framework and the routing protocol in a realistic setup. The simulation studies demonstrate that the proposed scheme provides substantial improvements in the delivery of real-time applications for a wide range of node densities, velocities, and data traffic.