text: We consider information dissemination in a large n -user wireless network in which k users wish to share a unique message with all other users. Each of the n users only has knowledge of its own contents and state information; this corresponds to a one-sided push-only scenario. The goal is to disseminate all messages efficiently, hopefully achieving an order-optimal spreading rate over unicast wireless random networks. First, we show that a random-push strategy-where a user sends its own or a received packet at random-is order-wise suboptimal in a random geometric graph: specifically, Ω(√n) times slower than optimal spreading. It is known that this gap can be closed if each user has “full” mobility, since this effectively creates a complete graph. We instead consider velocity-constrained mobility where at each time slot the user moves locally using a discrete random walk with velocity v(n) that is much lower than full mobility. We propose a simple two-stage dissemination strategy that alternates between individual message flooding (“self promotion”) and random gossiping. We prove that this scheme achieves a close to optimal spreading rate (within only a logarithmic gap) as long as the velocity is at least v(n)=ω(√(logn k)). The key insight is that the mixing property introduced by the partial mobility helps users to spread in space within a relatively short period compared to the optimal spreading time, which macroscopically mimics message dissemination over a complete graph.
  @cite_1: Dissemination of common information through broadcasting is an integral part of wireless network operations such as query of interested events, resource discovery and code update. In this paper, we characterize the behavior of information dissemination in power-constrained wireless networks by defining two quantities, i.e., broadcast capacity and information diffusion rate and derive fundamental limits in both random extended and dense networks. We find that using multihop relay, the rate of broadcasting continuous stream is Θ(log(n)− α 2 ) in extended networks; while direct single-hop broadcast is efficient for dense networks. Furthermore, regardless of the density, information can diffuse at constant speed, i.e., Θ(1) in both extended and dense networks. The theoretical bounds obtained and proof techniques are instrumental to the modeling and design of efficient wireless network protocols.
  @cite_25: In this paper, we investigate the fundamental properties of broadcasting in mobile wireless networks. In particular, we characterize broadcast capacity and latency of a mobile network, subject to the condition that the stationary node spatial distribution generated by the mobility model is uniform. We first study the intrinsic properties of broadcasting, and present a broadcasting scheme that simultaneously achieves asymptotically optimal broadcast capacity and latency, subject to a weak upper bound on the maximum node velocity. We then investigate the broadcasting problem when the burden related to selecting relay nodes is taken into account, and present a combined distributed leader election and broadcasting scheme achieving a broadcast capacity and latency which is within a poly-logarithmic factor from optimal.
  @cite_8: Flooding based querying and broadcasting schemes have low hop-delays of Theta(1 R(n)) to reach any node that is a unit distance away, where R(n) is the transmission range of any sensor node. However, in sensor networks with large radio ranges, flooding based broadcasting schemes cause many redundant transmissions leading to a broadcast storm problem. In this paper, we study the role of geographic information and state information (i.e., memory of previous messages or transmissions) in reducing the redundant transmissions in the network. We consider three broadcasting schemes with varying levels of local information where nodes have: (i) no geographic or state information, (ii) coarse geographic information about the origin of the broadcast, and (Hi) no geographic information, but remember previously received messages. For each of these network models, we demonstrate localized forwarding algorithms for broadcast (based on geography or state information) that achieve significant reductions in the transmission overheads while maintaining hop-delays comparable to flooding based schemes. We also consider the related problem of broadcasting to a set of "spatially uniform" points in the network (lattice points) in the regime where all nodes have only a local sense of direction and demonstrate an efficient "sparse broadcast" scheme based on a branching random walk that has a low number of packet transmissions. Thus, our results show that even with very little local information, it is possible to make broadcast schemes significantly more efficient.
summary: Another line of work has studied spreading scaling laws using more sophisticated non-gossip schemes over static wireless networks, e.g. @cite_1 @cite_8 . Recently, Resta @cite_25 began investigating broadcast schemes for mobile networks with a source constantly propagating new data, while we focus on a different problem with multiple mobile sources each sharing distinct message. Besides, @cite_25 analyzed how to combat the adverse effect of mobility to ensure the same pipelined broadcasting as in static networks, whereas we are interested in how to take advantage of mobility to overcome the geometric constraints. In fact, with the help of mobility, simply performing random gossiping -- which is simpler than most non-gossip schemes and does not require additional overhead -- is sufficient to achieve optimality.