We present Greedy Perimeter Stateless Routing (GPSR), a novel routing protocol for wireless datagram networks that uses the positions of routers and a packet's destination to make packet forwarding decisions. GPSR makes greedy forwarding decisions using only information about a router's immediate neighbors in the network topology. When a packet reaches a region where greedy forwarding is impossible, the algorithm recovers by routing around the perimeter of the region. By keeping state only about the local topology, GPSR scales better in per-router state than shortest-path and ad-hoc routing protocols as the number of network destinations increases. Under mobility's frequent topology changes, GPSR can use local topology information to find correct new routes quickly. We describe the GPSR protocol, and use extensive simulation of mobile wireless networks to compare its performance with that of Dynamic Source Routing. Our simulations demonstrate GPSR's scalability on densely deployed wireless networks.

/pdf/gpsr-greedy-perimeter-stateless-routing-for-wireless-59gz21qf8y.pdf

GPSR: greedy perimeter stateless routing for wireless networks

https://www.cs.montana.edu/courses/csci566/Ref/CR-Survey.pdf

NeXt generation/dynamic spectrum access/cognitive radio wireless networks: a survey

Advances in processor, memory and radio technology will enable small and cheap nodes capable of sensing, communication and computation. Networks of such nodes can coordinate to perform distributed sensing of environmental phenomena. In this paper, we explore the directed diffusion paradigm for such coordination. Directed diffusion is datacentric in that all communication is for named data. All nodes in a directed diffusion-based network are application-aware. This enables diffusion to achieve energy savings by selecting empirically good paths and by caching and processing data in-network. We explore and evaluate the use of directed diffusion for a simple remote-surveillance sensor network.

/pdf/directed-diffusion-a-scalable-and-robust-communication-4tsx5vxsas.pdf

Directed diffusion: a scalable and robust communication paradigm for sensor networks

"A Survey of Mobility Models for Ad Hoc Network Research," Wireless Comm. & Mobile Computing (WCMC) : Special issue on Mobile Ad Hoc Networking : Research

In the performance evaluation of a protocol for an ad hoc network, the protocol should be tested under realistic conditions including, but not limited to, a sensible transmission range, limited buffer space for the storage of messages, representative data traffic models, and realistic movements of the mobile users (i.e., a mobility model). This paper is a survey of mobility models that are used in the simulations of ad hoc networks. We describe several mobility models that represent mobile nodes whose movements are independent of each other (i.e., entity mobility models) and several mobility models that represent mobile nodes whose movements are dependent on each other (i.e., group mobility models). The goal of this paper is to present a number of mobility models in order to offer researchers more informed choices when they are deciding upon a mobility model to use in their performance evaluations. Lastly, we present simulation results that illustrate the importance of choosing a mobility model in the simulation of an ad hoc network protocol. Specifically, we illustrate how the performance results of an ad hoc network protocol drastically change as a result of changing the mobility model simulated.

/pdf/a-survey-of-mobility-models-for-ad-hoc-network-research-ygkxat400x.pdf

A survey of mobility models for ad hoc network research

Byzantine broadcast (BB) and Byzantine agreement (BA) are two most fundamental problems and essential building blocks in distributed computing, and improving their efficiency is of interest to both theoreticians and practitioners. In this paper, we study extension protocols of BB and BA, i.e., protocols that solve BB/BA with long inputs of $l$ bits using lower costs than $l$ single-bit instances. We present new protocols with improved communication complexity in almost all settings: authenticated BA/BB with $t<n/2$, authenticated BB with $t<(1-\epsilon)n$, unauthenticated BA/BB with $t<n/3$, and asynchronous reliable broadcast and BA with $t<n/3$. The new protocols are advantageous and significant in several aspects. First, they achieve the best-possible communication complexity of $\Theta(nl)$ for wider ranges of input sizes compared to prior results. Second, the authenticated extension protocols achieve optimal communication complexity given the current best available BB/BA protocols for short messages. Third, to the best of our knowledge, our asynchronous and authenticated protocols in the setting are the first extension protocols in that setting.

Improved Extension Protocols for Byzantine Broadcast and Agreement

This report contains two related sets of results with different assumptions on synchrony. The first part is about iterative algorithms in synchronous systems. Following our previous work on synchronous iterative approximate Byzantine consensus (IABC) algorithms, we provide a more intuitive tight necessary and sufficient condition for the existence of such algorithms in synchronous networks1. We believe this condition and the previous results also hold in partially asynchronous algorithmic model. 
In the second part of the report, we explore the problem in asynchronous networks. While the traditional Byzantine consensus is not solvable in asynchronous systems, approximate Byzantine consensus can be solved using iterative algorithms.

/pdf/iterative-approximate-byzantine-consensus-in-arbitrary-1emz071xtq.pdf

Iterative Approximate Byzantine Consensus in Arbitrary Directed Graphs - Part II: Synchronous and Asynchronous Systems

Proceedings of the 3rd international workshop on Discrete algorithms and methods for mobile computing and communications

In this paper, we propose a protocol for synchro- nizing time in multihop wireless networks. Protocols for power management or dynamic channel assignment often require syn- chronous operations, such as waking up at the same time or listen- ing to a common channel. Having the nodes synchronized in time is often crucial for these protocols to work. However, the exist- ing synchronization mechanisms do not work well with these pro- tocols because either they may fail to synchronize the time even without transient failures or packet loss, or they may require a large overhead. The proposed synchronization protocol, called MTSF (Multihop Timing Synchronization Function), successfully synchronizes time in a multihop network, at a low cost. In the absence of packet loss, MTSF guarantees an upper bound on the clock error between any two pair of nodes in the network. More- over, MTSF can tolerate packet losses to some extent and its per- formance degrades gracefully when the loss rate becomes high. The cost of MTSF increases very slowly as the number of nodes increase, which makes the protocol highly scalable. MTSF is fully distributed, and operates without a central coordinator. Finally, MTSF is self-stabilizing, which means that starting from an arbi- trary state, the protocol converges to a steady state. Due to these features, MTSF can support protocols that require synchronous operations at a low cost.

/pdf/mtsf-a-timing-synchronization-protocol-to-support-12x7uhlptl.pdf

MTSF: A Timing Synchronization Protocol to Support Synchronous Operations in Multihop Wireless Networks

With the fast growing uses of GPS-equipment, mobile users can more easily determine where they are located. These physical location information may play an important role in a wireless ad hoc network formed by a collection of wireless mobile hosts, in the absence of any fixed infrastructure. Performance overhead considerations are more important for ad hoc network environments because of the time-varying network topology. We propose some approaches to reduce the overhead at the network layer using location information of mobile hosts.

Nitin H. Vaidya

Papers

Improved Extension Protocols for Byzantine Broadcast and Agreement

Iterative Approximate Byzantine Consensus in Arbitrary Directed Graphs - Part II: Synchronous and Asynchronous Systems

Proceedings of the 3rd international workshop on Discrete algorithms and methods for mobile computing and communications

MTSF: A Timing Synchronization Protocol to Support Synchronous Operations in Multihop Wireless Networks

Using location information in wireless ad hoc networks