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Hybrid routing protocols in Ad Hoc networks combine proactive routing protocols with on-demand routing protocols and take advantages of both. However, the cost in delays and overheads resulted from simple domain formation algorithm of existing hybrid routing protocols is a main obstacle in improving the performance of overall ad hoc network. Owing to the above issues, in this paper we creatively apply the idea of clustering routing to hybrid routing protocols and propose a centralized adaptive hybrid routing protocol referred to as CAHR. In CAHR, several key nodes are selected using the centralized adaptive selection algorithm and different domains are formed according to the key nodes elected. By taking advantages of the key nodes, redundancy of routing forward is avoided, routing overheads are reduced and as a consequence, routing efficiency is improved. With simulations in OPNET Modeler of various scenarios, the superiority of CAHR is verified over traditional hybrid routing protocols in routing overheads, end-to-end latency, throughput and packet delivery rate.

This paper presents a relay routing method for Radio and TV services, this method through obtaining node’s timedelay and power information, obtains the value of system interrupt decisions, and as a decision threshold to select relay node. While in consideration of link priorities and fairness, we design a relay routing protocol that can dynamically change the route when network is changed. Simulation results show that this protocol can expand coverage, reduce communication blind spots, increase system throughput and enhance the quality of service.

In this paper, we implement a prototype of smart-home system based on the IPv6 over Low power Wireless Personal Area Networks, 6LoWPAN. The seamless connection is built between the wireless sensor networks (WSNs) and the Internet, which makes users visit the smart-home system through other IP-based networks. We also implement a routing protocol based on AODV-jr and embed it into 6LoWPAN. Imote2 platforms are used to verify our system. Meanwhile, this system provides a user-friendly interface to monitor and control the whole system by using web service technology. Furthermore, the system can be deployed easily and experimental results show that the design of our smart-home system can be served timely and reliably.

The management technology of Mobile Ad Hoc Networks (MANETs) has functions of monitoring, organizing and controlling communications services. Though the technology has gained great achievements in theory, its civil practical application is finite. One of the reasons is that MANETs are particularly difficult to manage due to the dynamic, heterogeneous and low-band-width connectivity. The Ad Hoc network management system in this paper is based on a novel network management mechanism and an improved embedded ARM-Linux terminal. The test shows that the system has managed the resource-restrained network on a small scale efficiently, which could carry out practical application of the Ad Hoc technology in the field of academic studies, military and commerce.

Heretofore, most of previous analyses in Mobile Ad Hoc Networks (MANETs) have been performed using simulators, which are largely different from the real MANET test-bed with the complicated and dynamic connectivity. In order to study the Ad Hoc network characteristics in the real environment, the paper presents a design method of mobile node specially for MANETs based on the embedded ARM-Linux. The classic protocol named Dynamic Source Routing (DSR) is transplanted into the embedded ARM-Linux platform. The investigated scenario involves a stationary test-bed that includes ARM mobile nodes connected using IEEE 802.11 in the Ad-Hoc working mode. Finally, the performance of mobile nodes is examined. The experimental results show that mobile nodes can work efficiently and reliably, which realize the function of the Ad Hoc network successfully.

The probability of successful packet delivery in ad hoc networks can be guaranteed by multi-path routing scheme, which can enhance network reliability. With the analysis on the path number, a decision making method based on packet drop ratio is introduced; moreover, a novel adaptive multi-path routing protocol is proposed. By monitoring packet drop ratio on the links, mobile nodes estimate link status with the pre-defined threshold, thus the partial-disjoint multi-path can be established under current network topology adaptively. Simulation results show this mechanism can provide reliable transmission for data packet and enhance the performance of the entire network while utilizing the network resource effectively.

A novel bandwidth routing mechanism is proposed, where all the nodes in network estimate bandwidth periodically. In our bandwidth estimating mechanism, the average size of contention window is used to evaluate the frame collision status and frame numbers which need to be retransmitted; furthermore, the estimation procedure is accomplished with the method of cooperation among mobile nodes. With the constraints of bandwidth and hop count, the optimal path can be set up by source node. Simulations show that frames collision status can be evaluated based on average size of contention window, and then available bandwidth can be estimated accurately; moreover, with the proposed routing method, the route establishment times can be reduced effectively, so the performance of ad hoc network is improved.

A Bloom filter is a simple space-efficient randomized data structure for representing a set in order to support membership queries. According to its space-efficient character, Bloom filter can be used in the mobile ad hoc networks (MANET), whose nodes have limited storage space and computational ability. Load balancing can distribute the traffic equally in the network after detecting the flows in each node accurately. By using Bloom Filter, single-path load balancing mechanism is used to distribute the traffic evenly among the nodes in the network without importing the route coupling problem of multi-path load balancing. Simulations show that the network performance is enhanced by single- path load balancing mechanism, and using Bloom Filter can save lots of storage space without affecting the detection accuracy.

For IEEE 802.16 broadband wireless access (BWA) system, the support of QoS is of prime importance for providing various traffic profiles in wireless links. Scheduling and resource allocation play the key roles in providing QoS as well as making better use of limited radio resources. This paper proposes an efficient scheduling algorithm for IEEE 802.16 OFDMA system with adaptive allocation of time-frequency resources. We utilize a user and connection based scheme to offer more efficient and QoS-guaranteed performance. The users' signal-to-noise ratio (SNR) on subchannels and their distribution characteristics are also taken into consideration. A new allocation scheme based on maximum deviation channel first (MDCF) is proposed to use the resources more efficiently. The fundamental of allocation scheme is to satisfy the QoS requirements of users as much as possible first, and to maximize system throughput thereafter. The simulation results show that the proposed scheduling and resource allocation algorithm can provide diverse QoS guarantees and use resources efficiently.