Real world MANETs often exhibit an inherent community structure in their topological connectivity and in the evolution of the topology over time. Such temporal community structure of MANETs has been shown to be extremely useful in improving the performance of routing and content-based routing in MANETs. However, detecting temporal communities in a completely distributed and real time manner is a hard problem, and it is often performed offline with knowledge of the full network topology over time. We propose CLAN, a distributed and real-time protocol for detecting temporal communities in MANETs. CLAN is an adaptation of the Label Propagation algorithm to distributed and time-varying graphs that MANETs are. A key novel component of CLAN is local rules for community rediscovery as the network evolves. CLAN also uses a weighted version of the network topology where the weights are defined using a novel notion of social entropy to promote stability of communities. Extensive simulation results demonstrate that CLAN is quick to converge, incurs minimal overhead and is as effective as centralized approaches to temporal community detection. We also demonstrate how the temporal community structure can be used by designing a hierarchical routing protocol that achieves the delivery ratio of the OLSR routing protocol at a fraction of the overhead.

We design a protocol for dynamic prioritization of data on shared routers such as untethered 3G/4G devices. The mechanism prioritizes bandwidth in favor of users with the highest value, and is incentive compatible, so that users can simply report their true values for network access. A revenue pooling mechanism also aligns incentives for sellers, so that they will choose to use prioritization methods that retain the incentive properties on the buy-side. In this way, the design allows for an open architecture. In addition to revenue pooling, the technical contribution is to identify a class of stochastic demand models and a prioritization scheme that provides allocation monotonicity. Simulation results confirm efficiency gains from dynamic prioritization relative to prior methods, as well as the effectiveness of revenue pooling.

We have created a sensor-sharing protocol that uses cognition to increase performance by choosing protocol parameters based on the current environment and the past relationships between environment and performance. We have constructed a prototype of the protocol, and experimented with it in a four-node outdoor testbed. Our testbed is part of a larger effort, ADROIT, which seeks to create cognitive teams of software-defined radios [l].

Transmit power control is a prototypical example of a cross-layer design problem. The transmit power level affects signal quality and, thus, impacts the physical layer, determines the neighboring nodes that can hear the packet and, thus, the network layer affects interference which causes congestion and, thus, affects the transport layer. It is also key to several performance measures such as throughput, delay, and energy consumption. The challenge is to determine where in the architecture the power control problem is to be situated, to determine the appropriate power level by studying its impact on several performance issues, to provide a solution which deals properly with the multiple effects of transmit power control, and finally, to provide a software architecture for realizing the solution. We distill some basic principles on power control, which inform the subsequent design process. We then detail the design of a sequence of increasingly complex protocols, which address the multidimensional ramifications of the power control problem. Many of these protocols have been implemented, and may be the only implementations for power control in a real system. It is hoped that the approach in this paper may also be of use in other topical problems in cross-layer design.

In this paper, we consider the problem of power control when nodes are nonhomogeneously dispersed in space. In such situations, one seeks to employ per packet power control depending on the source and destination of the packet. This gives rise to a joint problem which involves not only power control but also clustering. We provide three solutions for joint clustering and power control. The first protocol, CLUSTERPOW, aims to increase the network capacity by increasing spatial reuse. We provide a simple and modular architecture to implement CLUSTERPOW at the network layer. The second, Tunnelled CLUSTERPOW, allows a finer optimization by using encapsulation, but we do not know of an efficient way to implement it. The last, MINPOW, whose basic idea is not new, provides an optimal routing solution with respect to the total power consumed in communication. Our contribution includes a clean implementation of MINPOW at the network layer without any physical layer support. We establish that all three protocols ensure that packets ultimately reach their intended destinations. We provide a software architectural framework for our implementation as a network layer protocol. The architecture works with any routing protocol, and can also be used to implement other power control schemes. Details of the implementation in Linux are provided.

This work explores several system issues regarding the design and implementation of routing protocols for ad-hoc wireless networks. We examine the routing architecture in current operating systems and find it insufficient on several counts, especially for supporting on-demand or reactive routing protocols. Examples include lack of mechanisms for queuing outstanding packets awaiting route discovery and mechanisms for communicating route usage information from kernel to userspace. We propose an architecture and a generic API for any operating system to augment the current routing architecture. Implementing the API may normally require kernel modifications, but we provide an implementation for Linux using only the standard Linux 2.4 kernel facilities. The API is provided as a shared user-space library called the Ad-hoc Support Library (ASL), which uses a small loadable kernel module. To prove the viability of our framework, we provide a full-fledged implementation of the AODV protocol using ASL, and a design for the DSR protocol. Through this study, we also reinforce our belief that it is profoundly important to consider system issues in ad-hoc routing protocol design. 1