We study the problem of how to alleviate the exposed terminal effect in multi-hop wireless networks in the presence of log-normal shadowing channels. Assuming node location information, we propose an extension of the IEEE 802.11 MAC protocol that sched-ules concurrent transmissions in the presence of log-normal shadowing, thus mitigating the exposed terminal problem and improving network throug...

One interesting problem regarding wireless local area network (WLAN) ad-hoc networks is the effective mitigation of hidden nodes. The WLAN standard IEEE 802.11 provides request to send/clear to send (RTS/CTS) as mitigation for the hidden node problem; however, this causes the exposed node problem. The first 802.11 standard provided only two transmission rates, 1 and 2 Mbps, and control frames, ...

In this paper we introduce a graph problem, called Maximum Node Clustering (MNC). We prove that the problem is strongly NP -complete and show that it can be approximated in polynomial time within a ratio arbitrarily close to 2. For the special case where the graph is a tree, we prove that the problem is weakly NP -complete as it generalizes the 0/1 Knapsack problem and is solvable in pseudopoly...

Hadoop MapReduce framework is an important distributed processing model for large-scale data intensive applications. The current Hadoop and the existing Hadoop distributed file system’s rack-aware data placement strategy in MapReduce in the homogeneous Hadoop cluster assume that each node in a cluster has the same computing capacity and a same workload is assigned to each node. Default Hadoop d...

Multilevel programming can provide the right mathematical formulations for modeling sequential decision-making problems. In such cases, it is implicit that each level anticipates optimal reaction of subsequent ones. Defender–attacker–defender trilevel programs are a particular case interest encompasses fortification strategy, followed by an attack, and consequent recovery defensive strategy. “M...

In this work, we analyze a sequential game played in graph called the Multilevel Critical Node problem (MCN). A defender and an attacker are players of game. The starts by preventively interdicting vertices (vaccination) from being attacked. Then, infects subset non-vaccinated and, finally, reacts with protection strategy. We provide first computational complexity results associated MCN its sub...