Abstract—We propose an adaptive online load-balancing protocol for Multi-Gateway Wireless Mesh Networks (WMNs) which, based on the current network conditions, balances load between gateways. Our protocol (GWLB) achieves two goals: (i) alleviating congestion in affected domains and (ii) balancing load to improve flow fairness across domains. As a result of applying GWLB the throughput and fairness of flows improves. The proposed scheme effectively takes into account the elastic nature of TCP traffic, and intra-flow and inter-flow interference when switching flows between domains. Through simulations, we analyze performance and compare with a number of proposed strategies, showing that GWLB outperforms them. In particular, we have observed average flow throughput gains of 104 % over the nearest gateway strategy. I.

Abstract — In this paper, we argue that additional radios should be placed according to the distribution of traffic load in WMN. We show that the capacity of a WMN is constrained by the bottleneck collision domain; hence, placing an equal number of radios at all nodes is not necessary. Only collision domains that need to support higher traffic load should be given more bandwidth by setting up additional radios, so that interfering wireless links would operate on different channels, avoiding interference and enabling multiple parallel transmissions. Furthermore, we determine the upper bound on capacity improvements, and show that much less radios are required compared to conventional k-NIC architectures.

Despite availability of multiple non-overlapping channels in the 2.4GHz and the 5GHz spectrum, most IEEE 802.11-based multi-hop ad hoc networks operate in a single channel. This substantially reduces the bandwidth

By spreading the workload across a sensor network, load balancing reduces hot spots in the sensor network and increases the energy lifetime of the sensor network. In this paper, we design a node-centric algorithm that constructs a loadbalanced tree in sensor networks of asymmetric architecture. We utilize a Chebyshev Sum metric to evaluate via simulation the balance of the routing trees produced by our algorithm. We find that our algorithm achieves routing trees that are more effectively balanced than the routing based on breadth-first search(BFS) and shortest-path obtained by Dijkstra's algorithm.

In this paper, we consider a mobile ad-hoc wireless access network in which mobile nodes can access the Internet via a stationary gateway node or access point. Mobile nodes that are outside the transmission range of the gateway can continue to communicate with the gateway via a multi-hop connection with their neighboring nodes. The Ad-hoc On-demand Distance Vector (AODV) routing protocol is extended by incorporating the concept of load-balancing (LB). We call this the LB-AODV routing protocol. Simulation results show that in a congested network environment, our proposed LB-AODV has a higher packet delivery fraction, a lower end-to-end delay and control overhead when compared with both AODV and gossip-based routing protocols.

In a wireless LAN environment, wireless stations with the strongest received signal can not be guaranteed to have the best quality of service if the population sharing the network capacity was not considered. In other words, within the same access point, the more the population, the less the shared bandwidth, and the worse the quality of service will be. In this paper, we proposed an Anticipative Agent Assistance which is an agent-based metric for evaluating and managing the resource of the wireless access points, computing the potential AP list, and providing clients with resource information of APs. We also propose a novel QoS feedback mechanism which allows users to promptly adjust the service quality with AAA according to the throughput and delay requirements. We evaluate the performance of our proposed method using the ns-2 simulator. Numerical results show that AAA help reduce the transmission delay, increase the throughput, improve the network utilization, accommodate more users, and provide load-balancing.

of this dissertation.

Abstract—Scheduling decisions can have a pronounced impact on the performance of multi-radio wireless systems. In this paper, we study the effects of dispatch policies and queue scheduling strategies on the user-perceived performance for Internet traffic flows in a multi-channel WLAN. Our work is carried out using simulation and an empirical Web workload trace, with mean response time as the primary performance metric. The simulation results demonstrate the good/bad combination of the dispach policy with queue scheduling strategy, the advantages of deferred dispatch over immediate dispatch, and the sensitivity of dispatch policies to heavy-tailed workload characteristics. The results also highlight the pros and cons of a simple lookahead scheduling policy, particularly in the presence of high variability workloads on a heterogeneous multi-channel system with random losses. Our results provide insights into efficient and robust scheduling policies for multi-channel WLANs. Keywords: Multi-channel wireless networks, Dispatch policy, Scheduling, Simulation I.

Abstract — Multi-radio multi-channel multi-hop wireless networks recently have drawn considerable research attention. A number of results have been presented on joint optimization of routing, link scheduling, and channel assignment in such networks. Although dynamic channel switching has some benefits, it also poses a number of challenges in managing the network protocols and causes delay in switching channels. In this paper, we study the static channel assignment problem by statically mapping a channel to each radio of the nodes. We first show that it is NP-complete to find a channel assignment such that the resulting network is connected while the number of assigned channels to each node is at most the number of its Network Interface Cards(NICs). Secondly, we give several novel methods that only use a small number of channels while resulting in a connected network. Thirdly, we present a novel method to assign channels such that the network will support a large number of simultaneous transmissions (thus possibly increasing the network throughput). Fourthly, We theoretically analyze the expected number of channels that a node needs to be able to operate so that it can result in a connected network with high probability. Finally, we conduct extensive simulations to study the performances of our algorithms. Our simulations show that our backbone based channel assignment method will give us a connected network without violating the NIC constraints with high probability. I.

We present PERT, a power-efficient scheme to deliver real-time data packets in sensor networks. Time-sensitive sensor data is common in applications such as hazard monitoring systems, traffic control systems and battlefield command systems. Such data are associated with end-to-end deadlines, within which they must reach the base station. We make two contributions in this work. First, we propose a novel loadbalanced routing scheme that distributes data packets evenly among the nodes relaying data towards the base station, avoiding bottlenecks and increasing the likelihood that packets will meet their deadlines. Second, we propose a method of grouping smaller packets into larger ones by delaying data transmissions at the relaying nodes whenever slack times are positive. Our packet grouping scheme significantly reduces packet transmissions, reduces congestion, and saves power in the sensor network. We verify the effectiveness of our approach through extensive simulations of wireless network