In wireless mesh networks, with the standard Optimized Link State Routing (OLSR) metric (i.e. hop count), traffic is routed on the shortest path without considering factors such as traffic distribution and link capacities. Consequently, some nodes may get overloaded from the uneven utilization of network resources. OLSR can be modified to use other link cost metrics, with route selection based on lowest cost path. With delay as the metric, OLSR reduces average round trip time but the load-aware routes may cause wide variance in delay and packet reordering due to route oscillations. We describe a new hybrid routing approach that combines the strength of a) link state routing (e.g. fast convergence), b) load-aware routing (e.g., avoiding congested paths) and c) cognitive routing (e.g. learning to avoid path oscillations). In particular, we investigate the use of Q-learning with OLSR to increase network capacity and reduce congestion delay. We present simulation results for a 36 node dynamic mobile ad hoc network, with standard OLSR, a non-cognitive load-aware OLSR (OLSR-D) and our new hybrid cognitive load-aware OLSR (OLSR-Q). We show that OLSR-Q >; OLSR-D >; OLSR in terms of reducing delay and increasing network capacity. Furthermore, we show that, unlike conventional cognitive Q-routing protocols, our hybrid approach does not reduce performance at low load. Although OLSR-Q can significantly reduce delay and improve capacity, the learning time can reduce connectivity and the distribution of more link state information can reduce raw link capacity. We show how adding OLSR, OLSR-D and OLSR-Q as routing options into the Cognitive Network Engineering Design Analytic Toolset (C-NEDAT), we can select the best routing protocol and parameters (e.g., learning rate) for a given network and its mission. We verify simulation performance improvements by implementing the OLSR-Q in on a 9 node wireless testbed.

We present a software library that aids in the design of mobile ad hoc networks (MANET). The OMAN design engine works by taking a specification of network requirements and objectives, and allocates resources which satisfy the input constraints and maximize the communication performance objective. The tool is used to explore networking design options and challenges, including: power control, adaptive modulation, flow control, scheduling, mobility, uncertainty in channel models, and cross-layer design. The unaddressed niche which OMAN seeks to fill is the general framework for optimization of any network resource, under arbitrary constraints, and with any selection of multiple objectives. While simulation is an important part of measuring the effectiveness of implemented optimization techniques, the novelty and focus of OMAN is on proposing novel network design algorithms, aggregating existing approaches, and providing a general framework for a network designer to test out new proposed resource allocation methods. In this paper, we present a high-level view of the OMAN architecture, review specific mathematical models used in the network representation, and show how OMAN is used to evaluate tradeoffs in MANET design. Specifically, we cover three case studies of optimization. The first case is robust power control under uncertain channel information for a single physical layer snapshot. The second case is scheduling with the availability of directional radiation patterns. The third case is optimizing topology through movement planning of relay nodes.

Path planning and network design are often treated by architects of mobile communication networks as separate problems. In fact, most mobile ad hoc network (MANET) designs do not consider the path that the network nodes would take as part of the objective set, but incorporate them in an abstract form as general constraints on mobility (limit on the initial configuration and the node velocity). It appears that significant performance improvement may be possible if multiobjective optimization is attempted on performance indices such as connectivity of the network and arrival time of all nodes at a specified terminal set. In this study we provide an efficient decentralized method for computing the Pareto optimal set of plans, and show the benefit of path planning under six different metrics of MANET performance.

The CECOM MOSAIC ATD encompasses an integrated set of diverse technologies to demonstrate rapidly deployable, secure, robust, assured-QoS communications among mobile ad hoc nodes. The assured IP QoS technology solution integrates DiffServ based QoS resource management with centralized admission control over a dynamic tactical network environment. We describe an outdoor demonstration of our QoS technology prototype over an on-the-move MANET running OLSR. This demonstration does not include IP mobility support, however provides an alternate route between the ad hoc nodes through the use of two distinct wireless networks. The demonstration exhibits route changes between single and multiple IP hops as the nodes drive, and shows handoff between wireless networks as they move out of range of one radio network to the other. We summarize our observations and empirical performance results for real-time traffic

The mobile IP (MIP) protocol for IP version 4 provides continuous Internet connectivity to mobile hosts. However, currently it has some drawbacks in the areas of survivability, performance, interoperability with protocols for providing QoS. We have proposed an alternative protocol, mobile IP with location registers (MIP-LR), which overcomes some of these drawbacks and is closer to the "service node" database approach used in the public switched telephone network (PSTN): before launching a packet to the mobile host, the sender first queries a database, called the home location register (HLR), to obtain the recipient's current location. MIP-LR is designed for operation in enterprise environments or within logical administrative domains. We focus on showing how MIP-LR enhances the survivability of MIP by eliminating some of the functions which MIP introduces for mobility support, allowing the HLR to be placed outside the mobile's home network in case the latter is particularly vulnerable, and replicating and distributing HLRs. We present two schemes for managing the multiple HLRs and enabling mobile and correspondent hosts to dynamically discover the addresses of the HLRs serving a given mobile host. The first scheme introduces a set of translation server (TS) databases while the second uses a form of quorum consensus based on the triangle lattice (TL); for the latter we present an enhanced protocol called the optimistic TL(OTL). For both schemes we present algorithms for mobile host registration and packet delivery, protocols for recovery from HLR failures, and complexity analysis of the overhead involved.

The mobile IP (MIP) protocol for IP version 4 as being standardized by the Internet community provides continuous Internet connectivity to mobile hosts, without requiring any changes to existing routers and higher-layer applications. We propose an alternative protocol, mobile IP with location registers (MIP-LR) which is closer to the "service node" database approach used in the public switched telephone network (PSTN): before launching a packet to the mobile host, the sender first queries a database to obtain the recipient's current location. MIP-LR is designed for operation in enterprise environments or within logical administrative domains, as it requires a sending host to be aware of which hosts are potentially mobile and implement the MIP-LR protocol. The benefits of MIP-LR are that potentially long routes, called "triangle routes", from the sender to the mobile host are avoided, encapsulation of packets sent to a mobile host is not required, the load on the home network as well as the home and foreign agents is reduced, and there is substantially improved interoperability with protocols such as RSVP for providing QoS guarantees. We carry out a simplified average-case analysis of the costs and benefits of MIP-LR and show it can result in significant reductions in mean network costs compared to MIP.