Mobile ad hoc networks (MANETs) are becoming increasingly common, and typical network loads considered for MANETs are increasing as applications evolve. This, in turn, increases the importance of bandwidth efficiency while maintaining tight requirements on energy consumption, delay and jitter. Coordinated channel access protocols have been shown to be well suited for highly loaded MANETs under uniform load distributions. However, these protocols are in general not as well suited for non-uniform load distributions as uncoordinated channel access protocols due to the lack of on-demand dynamic channel allocation mechanisms that exist in infrastructure based coordinated protocols. In this paper, we present a lightweight dynamic channel allocation mechanism and a cooperative load balancing strategy that are applicable to cluster based MANETs to address this problem. We present protocols that utilize these mechanisms to improve performance in terms of throughput, energy consumption and inter-packet delay variation (IPDV). Through extensive simulations we show that both dynamic channel allocation and cooperative load balancing improve the bandwidth efficiency under non-uniform load distributions compared to protocols that do not use these mechanisms as well as compared to the IEEE 802.15.4 protocol with GTS mechanism and the IEEE 802.11 uncoordinated protocol.

Volunteer computing provides a practical and low cost solution to the increasing computational demands of many applications. Recent advancements in mobile device processing capabilities, combined with the energy efficiency of the mobile devices, make their inclusion in a distributed computing architecture particularly appealing. However, the intrinsic requirement of Internet connectivity to participate in volunteer computing limits the direct adoption of mobile devices due to service availability or related costs to connect to the Internet. In this paper, we propose and implement a novel computational architecture that extends the ability of mobile devices to participate in volunteer computing through ad hoc networking. By introducing decentralized task distribution points, mobile devices are invited to join the computation via device to device communication, removing the requirement for an Internet connection. Using a prototype implementation running on Android devices, we investigate the impact of a promising ad hoc communication technology, namely WiFi Direct, and two task distribution algorithms with different computation and communication overheads, under various scenarios. Experimental results show that our proposed approach is feasible with only minor additional energy consumption at the decentralized task distribution points.

An important aspect of the MAC layer design for mobile ad hoc networks (MANETs) is the ability to adapt to spatially non-uniform traffic load distributions. While coordinated channel access protocols have been shown to be well suited for highly loaded MANETs, these protocols are in general not as well suited for non-uniform load distributions as uncoordinated channel access protocols. In order to improve the performance of coordinated MAC protocols for MANETs under non-uniform load distribution, in this paper we apply to MANETs the dynamic channel allocation concept used in cellular networks. We present a new coordinated MAC protocol called DCA-TRACE (Dynamic Channel Allocation for TRACE), which is a sequel of our earlier MH-TRACE protocol. In addition to the mechanisms that exist in MH-TRACE for throughput and energy efficiency maximization, DCA-TRACE implements a distributed dynamic channel allocation strategy based on spectrum sensing. We compare DCA-TRACE with the MH-TRACE and 802.11 protocols in terms of throughput, energy consumption and interpacket delay variation (IPDV). Simulation results show that DCA-TRACE provides significant improvement for both uniform and non-uniform traffic loads.

It is increasingly common to see multiple wireless networks existing in the same environment, being accessed by devices of the individual networks as well as by "hybrid" devices capable of communicating on multiple networks. Typically these networks do not cooperate or share resources, resulting in sub-optimal network performances. The efficiency of such networks can be increased by exploiting hybrid nodes to enable network interactions that allow cross-network performance optimizations and cross-network information and service sharing. Such mutually beneficial interactions of the networks is referred to as symbiotic networking. In this paper, we investigate the potential performance gains of such interactions for the routing protocols and the effect of the network parameters on these potential gains. We use both simulation and mathematical frameworks that model the routing performances of both symbiotic and independent networking to quantify the routing benefits of symbiotic networking. Our results show that symbiotic networking can provide vital support to co-located networks, which is especially important in resource-constrained networks such as wireless sensor networks or mobile ad hoc networks.

Network-wide broadcasting and multicasting are two important routing schemes used in group communications. In network-wide broadcasting, generated packets at the source node are distributed to all nodes in the network, while multicasting delivers the packets only to a subset of the nodes by creating and maintaining a data dissemination structure. Due to the overhead in multicasting, in certain situations, it is more efficient to use network-wide broadcasting instead of multicasting, even when the data is destined to a subset of the nodes. In this paper we analyze a specific broadcasting protocol and a specific multicasting protocol for two performance metrics, namely spectrum efficiency and energy efficiency, and determine the conditions that make one of them preferable over the other.

Soft clustering of the nodes combined with time division multiple access (TDMA) channel access within a cluster has been shown to provide an energy-efficient solution for mobile ad-hoc networks (MANET). Such channel access schemes use a parameter that is critical in determining network performance: the number of frames per superframe, which determines the amount of spatial reuse possible, similar to the frequency reuse factor in cellular networks. When a smaller number of frames per superframe is used, each frame will consist of a larger number of slots, enabling the frame (i.e., cluster) to support more nodes, but also limiting the choices of frames for clusterheads to select, causing higher co-channel interference and collisions. Conversely, when a larger number of frames per superframe is used, the clusterheads will only be able to grant channel access to a limited number of nodes, which in turn increases the number of dropped packets (i.e., blocked channel access). The optimum value of the number of frames is the one that minimizes the combined effect of both collisions and dropped packets. By analytically determining the effects of dropped packets and collisions, we can find the optimal value for any given scenario. This paper develops a model to determine the optimal TDMA structure under various settings, showing the advantages that can be obtained by adapting protocol parameters as network conditions change.