This paper presents a simple local medium access control protocol, called , for multi-hop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the plane. In addition to these nodes, there are adversarial jammers that know the protocol and its entire history and that are allowed to jam the wireless channel at any node for an arbitrary @math -fraction of the time steps, where @math is an arbitrary constant. We assume that the nodes cannot distinguish between jammed transmissions and collisions of regular messages. Nevertheless, we show that achieves an asymptotically optimal throughput if there is a sufficiently dense distribution of nodes.
In the multi-channel version of the problem introduced in the theory community by Dolev @cite_17 and also studied in @cite_16 @cite_29 @cite_28 @cite_17 @cite_31 @cite_25 @cite_38 , a node can only access one channel at a time, which results in protocols with a fairly large runtime (which can be exponential for deterministic protocols @cite_29 @cite_31 and at least quadratic in the number of jammed channels for randomized protocols @cite_28 @cite_38 if the adversary can jam almost all channels at a time). Recent work @cite_16 also focuses on the wireless synchronization problem which requires devices to be activated at different times on a congested single-hop radio network to synchronize their round numbering while an adversary can disrupt a certain number of frequencies per round. @cite_25 study robust information exchange in single-hop networks.
@cite_38 @cite_28 @cite_29 @cite_31 @cite_16 @cite_25 @cite_17
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In this paper, we study the wireless synchronization problem which requires devices activated at different times on a congested single-hop radio network to synchronize their round numbering. We assume a collection of n synchronous devices with access to a shared band of the radio spectrum, divided into F narrowband frequencies. We assume that the communication medium suffers from unpredictable, perhaps even malicious interference, which we model by an adversary that can disrupt up to t frequencies per round. Devices begin executing in different rounds and the exact number of participants is not known in advance. We first prove a lower bound, demonstrating that at least Ω(log2n (F-t)loglogn + Ft F-t logn) rounds are needed to synchronize. We then describe two algorithms. The first algorithm almost matches the lower bound, yielding a running time of O(F F - t log2n + Ft F - t logn) rounds. The second algorithm is adaptive, terminating in O(t′ log3n) rounds in good executions, that is, when the devices begin executing at the same time, and there are never more than t′ frequencies disrupted in any given round, for some t′ This paper presents an efficient protocol for reliably exchanging information in a single-hop, multi-channel radio network subject to unpredictable interference. We model the interference by an adversary that can simultaneously disrupt up to t of the C available channels. We assume no shared secret keys or third-party infrastructure. The running time of our protocol depends on the gap between C and t: when the number of channels C =Omega(t^2), the running time is linear; when only C = t+1 channels are available, the running time is exponential. We prove that exponential-time is unavoidable in the latter case. At the core of our protocol lies a combinatorial function, possibly of independent interest, described for the first time in this paper: the multi-selector. A multi-selector generates a sequence of channel assignments for each device such that every sufficiently large subset of devices is partitioned onto distinct channels by at least one of these assignments. In this paper we consider the problem of designing a medium access control (MAC) protocol for single-hop wireless networks that is provably robust against adaptive adversarial jamming. The wireless network consists of a set of honest and reliable nodes that are within the transmission range of each other. In addition to these nodes there is an adversary. The adversary may know the protocol and its entire history and use this knowledge to jam the wireless channel at will at any time. It is allowed to jam a (1-epsilon)-fraction of the time steps, for an arbitrary constant epsilon>0, but it has to make a jamming decision before it knows the actions of the nodes at the current step. The nodes cannot distinguish between the adversarial jamming or a collision of two or more messages that are sent at the same time. We demonstrate, for the first time, that there is a local-control MAC protocol requiring only very limited knowledge about the adversary and the network that achieves a constant throughput for the non-jammed time steps under any adversarial strategy above. We also show that our protocol is very energy efficient and that it can be extended to obtain a robust and efficient protocol for leader election and the fair use of the wireless channel. The capacity problem in wireless mesh networks can be alleviated by equipping the mesh routers with multiple radios tuned to non-overlapping channels. However, channel assignment presents a challenge because co-located wireless networks are likely to be tuned to the same channels. The resulting increase in interference can adversely affect performance. This paper presents an interference-aware channel assignment algorithm and protocol for multi-radio wireless mesh networks that address this interference problem. The proposed solution intelligently assigns channels to radios to minimize interference within the mesh network and between the mesh network and co-located wireless networks. It utilizes a novel interference estimation technique implemented at each mesh router. An extension to the conflict graph model, the multi-radio conflict graph, is used to model the interference between the routers. We demonstrate our solution’s practicality through the evaluation of a prototype implementation in a IEEE 802.11 testbed. We also report on an extensive evaluation via simulations. In a sample multi-radio scenario, our solution yields performance gains in excess of 40 compared to a static assignment of channels.