Supporting cooperative caching in ad hoc networks

Most researches in ad hoc networks focus on routing and not much work has been done on data access. A common technique used to improve the performance of data access is caching. Cooperative caching, which allows the sharing and coordination of cached data among multiple nodes, can further explore the potential of the caching techniques. Due to mobility and resource constraints of ad hoc networks, cooperative caching techniques designed for wired networks may not be applicable to ad hoc networks. In this paper, we design and evaluate cooperative caching techniques to efficiently support data access in ad hoc networks. We first propose two schemes: CacheData, which caches the data, and CachePath, which caches the data path. After analyzing the performance of those two schemes, we propose a hybrid approach (HybridCache), which can further improve the performance by taking advantage of CacheData and CachePath while avoiding their weaknesses. Cache replacement policies are also studied to further improve the performance. Simulation results show that the proposed schemes can significantly reduce the query delay and message complexity when compared to other caching schemes.     

A route stability-based multipath QoS routing protocol in cognitive radio ad hoc networks

Wireless Networks - Secondary user (SU) mobility, primary user activity, and spectrum sensing inaccuracy are the main challenges to the stability of a quality of service (QoS) route in cognitive...     

SecMR – a secure multipath routing protocol for ad hoc networks

Multipath routing in ad hoc networks increases the resiliency against security attacks of collaborating malicious nodes, by maximizing the number of nodes that an adversary must compromise in order to take control of the communication. In this paper, we identify several attacks that render multipath routing protocols vulnerable to collaborating malicious nodes. We propose an on-demand multipath routing protocol, the secure multipath routing protocol (SecMR), and we analyze its security properties. Finally, through simulations, we evaluate the performance of the SecMR protocol in comparison with existing secure multipath routing protocols.     

SPREAD: Improving network security by multipath routing in mobile ad hoc networks

We propose and investigate the SPREAD scheme as a complementary mechanism to enhance secure data delivery in a mobile ad hoc network. The basic idea is to transform a secret message into multiple shares, and then deliver the shares via multiple paths to the destination so that even if a certain number of message shares are compromised, the secret message as a whole is not compromised. We present the overall system architecture and discuss three major design issues: the mathematical model for the generation and reconstruction of the secret message shares, the optimal allocation of the message shares onto multiple paths in terms of security, and the multipath discovery techniques in a mobile ad hoc network. Our extensive simulation results justify the feasibility and the effectiveness of the SPREAD approach.

Ad hoc网络中带宽保证路由协议

研究ad hoc网络中无线链路存在邻近链路干扰及隐藏终端和暴露终端问题，提出新的带宽预留模型及带宽保证路由协议(BGRP)，旨在按需探测符合带宽需要的路由路径并预留可靠的带宽资源。理论分析证明，BGRP探测的路由路径能满足带宽需要，而且预留的带宽资源准确有效。仿真结果表明，就有效带宽而言，BGRP较INSIGNIA和BGSR算法有效，而且消息复杂性较小，具有良好的网络扩展性。     

Delay constraint multipath routing for wireless multimedia ad hoc networks

According to the disadvantages of real time and continuity for multimedia services in ad hoc networks, a delay constraint multipath routing protocol for wireless multimedia ad hoc networks, which can satisfy quality of service (QoS) requirement (QoS multipath optimized link state routing [MOLSR]), is proposed. The protocol firstly detects and analyzes the link delay among the nodes and collects the delay information as the routing metric by HELLO message and topology control message. Then, through using the improved multipath Dijkstra algorithm for path selection, the protocol can gain the minimum delay path from the source node to the other nodes. Finally, when the route is launched, several node‐disjoint or link‐disjoint multipaths will be built through the route computation. The simulation and test results show that QoS‐MOLSR is suitable for large and dense networks with heavy traffic. It can improve the real time and reliability for multimedia transmission in wireless multimedia ad hoc networks. The average end‐to‐end delay of QoS‐MOLSR is four times less than the optimized link state routing. Copyright © 2014 John Wiley & Sons, Ltd.     

Ad hoc网络中一种自适应分簇路由过渡协议

针对ad hoc网络中传统平面路由协议扩展性不佳的问题,利用被动分簇和渐进分簇的有效机制,融入自适应分簇和路由过渡的思想,提出了自适应分簇路由过渡协议(ACRT),并通过仿真与传统的按需路由协议(AODV)以及被动分簇和渐进分簇等协议在不同网络规模下进行了比较.实验表明,ACRT具有优越的可扩展性,在与传统平面路由协议和同类协议比较的各项指标中表现均衡,是一种稳定、高效、实用的路由机制.     

Interference aware cooperative routing for wireless ad hoc networks

In this paper, we propose a cooperative approach for routing in wireless ad hoc networks. Our solution improves the interference distribution in the network, with an immediate positive impact on the throughput performance and energy efficiency. In determining new routes, we consider not only the cost associated with the current route, but also the potential interference impact of the route on the neighboring nodes.We use this cooperative approach to determine routes for CDMA ad hoc networks, which are known to be severely limited in performance by the near–far effect. Our simulation results using cooperative routing show an improvement in throughput of up to 60% compared to the classic minimum energy routing approach. This improvement is achieved at the expense of only a slight increase in the average energy per bit transmission for an end-to-end path.     

Secure position-based routing protocol for mobile ad hoc networks

In large and dense mobile ad hoc networks, position-based routing protocols can offer significant performance improvement over topology-based routing protocols by using location information to make forwarding decisions. However, there are several potential security issues for the development of position-based routing protocols. In this paper, we propose a secure geographic forwarding (SGF) mechanism, which provides source authentication, neighbor authentication, and message integrity by using both the shared key and the TIK protocol. By combining SGF with the Grid Location Service (GLS), we propose a Secure Grid Location Service (SGLS) where any receiver can verify the correctness of location messages. We also propose a Local Reputation System (LRS) aiming at detecting and isolating both compromised and selfish users. We present the performance analysis of both SGLS and LRS, and compare them with the original GLS. Simulation results show that SGLS can operate efficiently by using effective cryptographic mechanisms. Results also show that LRS effectively detects and isolates message dropping attackers from the network.     

Polarization-based cooperative directional MAC protocol for ad hoc networks

Numerous directional medium access control (DMAC) protocols have been developed to enhance the capacity of ad hoc networks using the underlying advanced physical layer techniques, such as beam-forming, multiuser detection (MUD), and multiple-input–multiple-output (MIMO). In this paper, we propose an innovative fully distributed DMAC protocol that cooperatively makes use of polarization diversity in low-mobility urban/suburban outdoor wireless ad hoc network environment. In the proposed cooperative polarization DMAC protocol (CPDMAC), each node directionally senses on both vertical and horizontal polarizations and dynamically adapts polarization that minimizes overall interference in the ad hoc network. Analysis is performed to establish relationship between vertically and horizontally polarized nodes in the network. Further, a theoretical lower bound is derived for probability of successful transmission to show capacity improvement as a function of cross polarization ratio (CPR). Simulation results confirm from 2% up to 400% improvement in average node throughput at data rate of 1.95 Mbps when compared to the traditional DMAC protocol. Moreover, our study clearly shows that the average throughput difference increases with increasing node density when compared to the traditional DMAC protocol.     

SMORT: Scalable multipath on-demand routing for mobile ad hoc networks

Increasing popularity and availability of portable wireless devices, which constitute mobile ad hoc networks, calls for scalable ad hoc routing protocols. On-demand routing protocols adapt well with dynamic topologies of ad hoc networks, because of their lower control overhead and quick response to route breaks. But, as the size of the network increases, these protocols cease to perform due to large routing overhead generated while repairing route breaks. We propose a multipath on-demand routing protocol (SMORT), which reduces the routing overhead incurred in recovering from route breaks, by using secondary paths. SMORT computes fail-safe multiple paths, which provide all the intermediate nodes on the primary path with multiple routes (if exists) to destination. Exhaustive simulations using GloMoSim with large networks (2000 nodes) confirm that SMORT is scalable, and performs better even at higher mobility and traffic loads, when compared to the disjoint multipath routing protocol (DMRP) and ad hoc on-demand distance vector (AODV) routing protocol.     

Optimal rate allocation for energy-efficient multipath routing in wireless ad hoc networks

In this paper, we address the problem of energy efficiency in wireless ad hoc networks. We consider an ad hoc network comprising a set of sources, communicating with their destinations using multiple routes. Each source is associated with a utility function which increases with the total traffic flowing over the available source-destination routes. The network lifetime is defined as the time until the first node in the network runs out of energy. We formulate the problem as one of maximizing the sum of the source utilities subject to a required constraint on the network lifetime. We present a primal formulation of the problem, which uses penalty functions to take into account the system constraints, and we introduce a new methodology for solving the problem. The proposed approach leads to a flow control algorithm, which provides the optimal source rates and can be easily implemented in a distributed manner. When compared with the minimum transmission energy routing scheme, the proposed algorithm gives significantly higher source rates for the same network lifetime guarantee.     

A cluster-based trust-aware routing protocol for mobile ad hoc networks

Routing protocols are the binding force in mobile ad hoc network (MANETs) since they facilitate communication beyond the wireless transmission range of the nodes. However, the infrastructure-less, pervasive, and distributed nature of MANETs renders them vulnerable to security threats. In this paper, we propose a novel cluster-based trust-aware routing protocol (CBTRP) for MANETs to protect forwarded packets from intermediary malicious nodes. The proposed protocol organizes the network into one-hop disjoint clusters then elects the most qualified and trustworthy nodes to play the role of cluster-heads that are responsible for handling all the routing activities. The proposed CBTRP continuously ensures the trustworthiness of cluster-heads by replacing them as soon as they become malicious and can dynamically update the packet path to avoid malicious routes. We have implemented and simulated the proposed protocol then evaluated its performance compared to the clustered based routing protocol (CBRP) as well as the 2ACK approach. Comparisons and analysis have shown the effectiveness of our proposed scheme.     

低开销的MANET网络按需路由协议

针对简单泛洪效率低的问题,提出了一个限制洪泛的高效的路由广播算法,通过Euclidean距离来限制路由发现过程中请求分组被转发的次数;研究了减少路由维护开销,并降低路由发现的频率的方法,提出了一个基于节点高度的路由修复与优化算法,该算法使用节点监听来对链路断裂的路由进行修复与优化.基于限制泛洪的高效的路由广播算法和路由修复优化算法,提出了一种新的低开销的MANET网络按需路由协议LOOR(low overhead on-demand routing).仿真结果表明,新协议增强了路由的顽健性,减少了路由跳数,降低了路由发现的频率,提高了数据分组递送率,并显著地降低了路由控制开销.     

A region-based routing protocol for wireless mobile ad hoc networks

Flooding-based route discovery is widely assumed in existing routing protocols of wireless ad hoc networks. Network-wide flooding enables the discovery of optimal routes from sources to destinations; however, as all network nodes are required to participate in the relays of route request packets, substantial control overhead is inevitable. Some efficient broadcast schemes can suppress redundant packet relays, but they often suppress the discovery of optimal routes, too. In this article we propose to dynamically create a prerouting region between each source-destination pair and limit the propagations of route request packets only within this region. The prerouting region effectively restricts route discovery activities to the nodes that most likely constitute the optimal or near-optimal routes. Consequently, not only is route construction overhead significantly reduced; route optimality is also guaranteed. The article presents a region-based routing (REGR) protocol covering both new route formation cases and route update cases. Simulations show that our protocol is particularly beneficial to dense and large-scale mobile ad hoc networks.     

DIR: diagonal-intersection-based routing protocol for vehicular ad hoc networks

In this paper, we present a diagonal-intersection-based routing (DIR) protocol for vehicular ad hoc networks. The DIR protocol constructs a series of diagonal intersections between the source and destination vehicles. The DIR protocol is a geographic routing protocol. Based on the geographic routing protocol, source vehicle geographically forwards data packet toward the first diagonal intersection, second diagonal intersection, and so on, until the last diagonal intersection, and finally geographically reach to the destination vehicle. For given a pair of neighboring diagonal intersections, two or more disjoint sub-paths exist between them. The novel property of DIR protocol is the auto-adjustability, while the auto-adjustability is achieved that one sub-path with low data packet delay, between two neighboring diagonal intersections, is dynamically selected to forward data packets. To reduce the data packet delay, the route is automatically re-routed by the selected sub-path with lowest delay. The proposed DIR protocol allows the mobile source and destination vehicles in the urban VANETs. Experimental results show that the DIR protocol outperforms existing solutions in terms of packet delivery ratio, data packet delay, and throughput.     

Game theoretic approach in routing protocol for wireless ad hoc networks

This paper introduces a game theoretic method, called forwarding dilemma game (FDG), which controls routing overhead in dense multi-hop wireless ad hoc networks. The players of the game are the wireless nodes with set of strategies {Forward, Not forward}. The game is played whenever an arbitrary node in the network receives a flooding packet. In FDG, every player needs to know the number of players of the game. That is why a neighbor discovery protocol (NDP) is introduced. In order for NDP to function, a field is attached to the flooding packets (routing overhead packets). The mixed strategy Nash equilibrium is used as a solution for the FDG. This provides the probability that the flooding packet would be forwarded by the receiver node. FDG with NDP is implemented in AODV protocol in Network Simulator NS-2 to verify its performance with simulations. FDG with NDP improves performance of the AODV compared to the same network with only AODV protocol in moderate and high node densities. FDG can be applied to any routing protocol that uses flooding in the route discovery phase.     

A greedy-based stable multi-path routing protocol in mobile ad hoc networks

With the increasing popularity of multimedia, there is a growing tendency in mobile ad hoc networks (MANETs) to establish stable routes with long route lifetimes, low control overhead and high packet delivery ratios. According to recent analytical result, the lifetime of a route, which can reflect the route stability, depends on the length of the route and the lifetime of each link in the route. This paper presents a Greedy-based Backup Routing (GBR) protocol that considers both route length and link lifetime to achieve high route stability. In GBR, the primary path is constructed primarily based on a greedy forwarding mechanism, whereas the local-backup path for each link is established according to the link lifetime. Both analytical and simulation results demonstrate that GBR has excellent performance in terms of route lifetime, packet delivery ratio, and control overhead.     

一种新的基于ACSA的ad hoc多径QoS路由方法

ad hoc网络中基于蚁群系统算法（ACSA）的路由协议已经被广泛地研究,但其中的大部分本质上都属于单径路由协议,使得源宿之间最短路径上的主机负担加重。另一方面,由于引入了蚂蚁的正反馈机制,使得协议本身比较差的鲁棒性受到进一步的削弱,多径路由能够更好地支持QoS。本文将ACSA和链路不相交的多径路由结合起来以解决上述问题。新提出的基于ACSA的多径QoS路由方法建立和利用多条链路不相交路径来并发发送数据,并且采用信息素来分散通信流量,因此能够适应网络的动态变化和更好的支持QoS,仿真结果表明该方法要优于其他相关的算法。     

Neighbor caching in multi-hop wireless ad hoc networks

We propose a neighbor caching strategy to overcome the overhead of multi-hop wireless communications. Neighbor caching makes a node able to expand its caching storage instantaneously by storing its data in the storage of idle neighbors. We also present the ranking based prediction that selects the most appropriate neighbor which data can be stored in. The ranking based prediction is an adaptive algorithm that adjusts the frequency of neighbor caching and makes neighbor caching flexible according to the idleness of nodes.