Routing Discovery Algorithm Using Parallel Chase Packet

Ad Hoc Routing with Distributed Ordered Sequences

AODV(Ad Hoc On-Demand Distance Vector)나 DSR(Dynamic Source Routing)과 같은 대부분의 에드혹 라우팅 프로토콜은 네트워크 토폴로지가 변하지 않는 한 새로운 경로 설정을 하지 않는다. 따라서 노드의 이동성이 적은 경우, 트래픽은 몇몇 노드에게 집중될 수 있으며 그 결과로 해당 노드들의 혼잡으로 인한 긴 종단간 지연이 발생할 수 있다. 게다가 몇몇 특정 노드들만 오랫동안 계속해서 사용됨에 따라 그들의 배터리가 빠르게 소모될 것이다. 노드의 배터리 방전은 노드 사이의 연결 단절뿐만 아니라 동시에 새로운 경로 설정을 위하여 많은 route re-quest 패킷(RREQ)을 생성시킨다. 본 논문에서는 각 노드가 자신의 트래픽 부하 상태를 기반으로 RREQ 패킷을 무시하거나 패킷 포워딩을 포기할 수 있게 함으로써 트래픽 집중화 문제를 해결할 수 있는 SLA(Simple Load-balancing Approach)를 제안한다. 그러나 어떤 이기적인 노드들은 자신의 에너지를 절약하기 위하여 고의적으로 패킷 포워딩을 거부할 수도 있다. 이러한 노드들을 패킷 포워딩에 참여시키기 위하여 본 논문에서는 PIFA(Protocol-Independent Fairness Algorithm) 보상 방식을 제안하였다. SLA 성능의 우수함을 증명하기 위하여 SLA를 채택한 AODV 방식과 SLA를 채택하지 않은 AODV 방식을 비교 실험하였고, 이를 통하여 SLA를 채택한 방식이 트래픽 부하 분산에 효율적이며 이로 인하여 전체 에드혹 네트워크 성능 또한 향상시킴을 확인하였다. Most ad-hoc routing protocols such as AODV(Ad Hoc On-Demand Distance Vector) and DSR(Dynamic Source Routing) do not try to search for new routes if the network topology does not change. Hence, with low node mobility, traffic may be concentrated on several nodes, which results in long end-to-end delay due to congestion at the nodes. Furthermore, since some specific nodes are continuously used for long duration, their battery power may be rapidly exhausted. Expiration of nodes causes connections traversing the nodes to be disrupted and makes many routing requests be generated at the same time. Therefore, we propose a load balancing approach called Simple Load-balancing Approach (SLA), which resolves the traffic concentration problem by allowing each node to drop RREQ (Route Request Packet) or to give up packet forwarding depending on its own traffic load. Meanwhile, mobile nodes nay deliberately give up forwarding packets to save their own energy. To make nodes volunteer in packet forwarding. we also suggest a payment scheme called Protocol-Independent Fairness Algorithm (PIEA) for packet forwarding. To evaluate the performance of SLA, we compare two cases where AODV employs SLA or not. Simulation results show that SLA can distribute traffic load well and improve performance of entire ad-hoc networks.

With the onset of multimedia applications, Quality of Service (QoS) in 802.11-based wireless ad hoc networks has been an essential area to look into. Standard wireless protocols such as IEEE 802.11b and IEEE 802.11e have been deemed unsuitable for multimedia traffic transmission in an ad hoc (multihop) network environment due to the unique network characteristics. As an ad hoc network is infrastructureless and distributed in nature, it gives rise to several challenges in QoS provisioning. In this thesis, we focus on the research of three key areas on QoS in ad hoc networks namely, buffer management in the medium access control (MAC) layer, cross-layer design and flow admission control. Firstly, we study MAC layer buffer management in the IEEE 802.11e protocol. The IEEE 802.11e MAC protocol provides QoS for multimedia traffic by probabilistic priority queueing. Ad hoc networks tend to generate a large volume of network control packets for route maintenance and these control packets are typically queued in the highest priority queue. As a result, higher priority control traffic is always being served, consuming most of the bandwidth and results in poor network performance for data traffic. We examine this problem and propose a dynamic buffer management scheme to mitigate it. By setting different threshold levels in different priority queues, we allow lower priority data traffic to be served when the higher priority control traffic is deemed to be excessive. Simulation of our proposed scheme has shown that our approach yielded better network performance compared to the standard protocol in terms of packet delivery ratio and average delay. Secondly, we study the cross-layer interaction between the MAC and Network layers to identify its impact on QoS. We select the IEEE 802.11e MAC protocol and Ad-hoc On Demand Distance Vector (AODV) routing protocol in our study since they are standardized protocols for wireless networks. In IEEE 802.11e MAC protocol, lower priority traffic has a higher probability of being blocked. Hence, the MAC layer will inform the Network layer of a broken link through the link notification function. In this case, AODV will re-route the paths that traverse this link. As a result, higher priority traffic which shares the same link as the lower priority traffic will undergo the same re-routing procedures. We termed this phenomenon path correlation effect. Under high traffic load, the path correlation effect will be more intense and hence degrade the QoS of higher priority traffic. To break the path correlation effect, we propose a cross-layer design called the Bundled Virtual Circuit (BVC). Our proposed BVC scheme not only addresses the path correlation issues, but also provides priority treatment from the Network layer to the MAC layer. Through our simulations, our proposed cross-layer design approach is proven to provide better network performance than the 802.11e/AODV protocols in terms of packet delivery ratio and delay. Finally, we examine flow admission control at the routing layer in ad hoc networks. Standard routing protocols such as AODV performs routing on a shortest path basis. In the presence of multiple routes, hotspots are likely to form among the intermediate nodes and thus lead to network congestion. In addition, existing routes are not well-protected from the introduction of new routes. We propose a flow admission control algorithm to be used with AODV. Our algorithm allows routes to be created through available bandwidth and congestion estimation. During the route discovery phase, each node will be gauged on its estimated available bandwidth and its backlog of packets in the MAC buffer. If a node does not have sufficient bandwidth, or has too many backlogged packets compared to the requested flow rate, it will not participate in the route discovery process. From simulations, our new scheme is able to provide better network performance than the standard AODV protocol in terms of delay. Our work in this thesis focuses on QoS provisioning in ad hoc networks from the MAC and network layer perspectives. By studying the network characteristics and protocols’ behavior, we investigate the various problems of providing QoS in an ad hoc network environment and propose three different schemes to improve the QoS provisioning at the MAC and network layers. We believe that our work is able to provide some insights to the research area on QoS in ad hoc networks.

The Ad-hoc On Demand Distance Vector (AODV) is one of the most famed reactive routing protocols, which is used in Mobile Ad Hoc Networks (MANETs) for routing purposes, where the routes are built only when it is required. The AODV is related to the problem of route constructing and maintaining among any two-node in the presence of the dynamic topology of a network. High routing control packets, during route construction, is a limiting factor of AODV. Also, the route created during route discovery process may not be optimum (in terms of the number of hop counts between the originating and target node). The construction of non-optimal route arises from many reasons such as temporary congestion of one or more links in the short path to the target node, or nodes in those paths may contend the channel late, or the nodes may be busy for that moment to entertain other engagement. Moreover, during the route discovery phase, a large amount of unnecessary control packets may be generated which result in the debasement of the performance and the efficiency of the protocol by congesting the network and increasing the overhead. In this article the cases at which non-ideal routes are created and unimportant control packets generated during route discovery process will be identified. The modified AODV (AODV_MOD) with enhanced route discovery mechanism is proposed that will be used to avoid these cases by suppressing unimportant control packets and avoiding non-ideal routes formation. Simulation results, conducted in network simulator (NS2), prove the skillfulness of the proposed enhanced route discovery scheme from point of view of packet delivery ratio, endto-end delay, and normalized overhead.

In this paper, we efficiently adapt the prominent Ad hoc On-demand Distance Vector (AODV) routing protocol with a reactive Local Link Repair (AODV-LR) for effective deployment in Mobile Ad hoc Sensor Networks (MASNETs) with restricted power and bandwidth. We introduce two replacement mechanisms to the local repair phase of the AODV. Our new approaches are self-repairing AODV algorithms called Reactive Self-repairing AODV (AODV-RSR) and Pre-emptive Self-repairing AODV (AODV-PSR). These two algorithms are able to find an alternative route to a failing link without depending only on broadcasting Route Request (RREQ) packets. Experimental results show that the new algorithms achieve better performance than the AODV-LR and Self-repair Algorithm (SRAODV) by obtaining lower packet delay, higher packet delivery ratio and lower control message overhead.

Growing demand in wireless Mobile Adhoc Networks due to their immense potential and effectiveness in varied applications had motivated researchers to control and optimize various parameters for efficient routing in mobile environment. The rapidly changing environment of the network due to mobility of nodes results in unpredictable topology and thus introduces primary challenge to design better and an efficient routing protocol. The network in such case lacks fixed infrastructure and common head centric design. MANET routing schemes use flooding to propagate packets in the network resulting retransmissions, collisions, and congestions which significantly degrade the performance of the network. Using GPS, knowing the geographical position of the sensor nodes, the protocol performance can be improved while reducing the number of retransmissions. The proposed work is a future extension of efficient flooding based on selective neighbours where the surrounding region limiting the transmission range is divided into eight quadrants or zones with the source at the centre called zone based selective neighbours (ZBSN). Flooding based on selective four neighbours suffers from few selection of hoping or forwarding nodes when the node density is low and does not meet the selection criteria around the source or forwarder node and may miss the chance of approaching the destination or requires large number of hops. This neighbour selection scheme uses the modified approach of the Adhoc on Demand Distance Vector (AODV) protocol to reduce the flooding of Route request (RREQ) packets, control the network overall traffic, improves link stability and the residual energy reducing the overheads by 24%.

Mobile Ad Hoc Networks (MANETs) pose challenges in terms of power control, due to their fixed transmission power, the mobility of nodes and a constantly changing topology. High levels of power are needed in wireless networks, particularly for routing. In order to address this problem, power aware routing protocols have been proposed, with the aim of maximising the lifetime of the network. This paper presents an enhancement to the Ad Hoc On Demand Distance Vector (AODV) protocol, by reducing transmission power, when a large number of other radios are within range. This protocol, called DP-AODV (Dynamic Power AODV) combines the hello packet mechanism and the power control mechanism in order to reduce interference between nodes and increase the throughput in the network, thus reducing the overall power consumption. A performance evaluation of this enhanced protocol is carried out in comparison with three standard routing protocols, Ad Hoc On Demand Distance Vector (AODV), Ad Hoc On Demand Multipath Distance Vector (AOMDV) and Dynamic Source Routing (DSR), using network simulator 2 (NS2). Keywords-MANET; Dynamic Power; Density; Mobility; Interference.

Recently mobile ad-hoc networks (MANET) have found widespread applications. In this infrastructure-less networks the routes have to be refreshed often due to mobility of nodes which also acting as routers. Many ad-hoc routing protocols have been proposed, of which on-demand routing protocols are very popular. To meet the scarce of network resources, the need of the time is to develop a protocol which makes efficient use of resources. In this paper we propose a mobility adaptive cross layer design to enhance the performance of ad-hoc on-demand distance vector (AODV) routing protocol by establishing stable routes. The adaptive decision making according to the speed of mobile nodes on route request (RREQ) packet forwarding results in stable routes. Comparing with the basic AODV protocol, the new cross layer algorithm has better performance as shown with the simulation results obtained using the network simulator, GloMoSim.

Mobile ad hoc network (MANET) is lacking infrastructure support, so nodes of MANET are vulnerable to attacks. Denial of Service attacks (DOS) makes network inaccessible to users. Black hole attack is a type of DOS attack, in which mischievous node claims that it has a route towards the destination node. Ad Hoc on Demand Distance Vector (AODV) routing protocol is affected by Black hole attack. The proposed solution is based on first Route Reply (RREP) caching mechanism in AODV protocol. Simulation results show performance improvement in routing protocol.

A Mobile Ad Hoc Network (MANET) protocol requires proper settings to perform data transmission optimally. To overcome this problem, it is necessary to select the correct routing protocol and use the routing protocol’s default parameter values. This study examined the effect of route request parameters, such as RREQ_RETRIES and MAX_RREQ_TIMOUT, on the Ad Hoc On-demand Distance Vector (AODV) protocol, which was then compared with the default AODV performance Optimized Link State Routing (OLSR) protocols. The performance metrics used for measuring performance were Packet Delivery Ratio (PDR), throughput, delay, packet loss, energy consumption, and routing overhead. The results show that the OLSR protocol has a smaller delay than the AODV protocol, while in other measurements, the AODV protocol is better than OLSR. By reducing the combination value of RREQ_RETRIES, MAX_RREQ_TIMEOUT in AODV routing to (2, 10 s) and (3, 5 s), the protocol’s performance can be improved. The two combinations result in an average increase in throughput performance of 3.09%, a decrease in delay of 17.7%, a decrease in packet loss of 27.15%, and an increase in PDR of 4.8%. For variations in the speed of movement of nodes, 20 m/s has the best performance, while 5 m/s has the worst performance.

Wireless mobile ad hoc stations have limited battery capacity, hence, ad hoc routing protocols ought to be energy conservative. Route discovery is a common operation in routing to resolve many issues. In a mobile ad hoc network (MANET) in particular, due to host mobility, such operations are expected to be executed more frequently. A straightforward broadcasting by flooding is usually very costly and will result in serious redundancy, contention, and collision, resulting in broadcast storm problem. In this paper, an algorithm is proposed to improve flooding performance of ad hoc on-demand distance vector (AODV) routing protocol called, probabilistic-average-energy- flooding (PAEF) which periodically performs an averaging algorithm calculate-average-energy (CAE) to estimate the average energy E avg. This algorithm is used in route discovery process to make a rebroadcast decision by the node. Our simulation results show an improvement in the network lifetime and the throughput compared to traditional AODV.

Hybrid Wireless Mesh Networks (HWMNs) based on the IEEE 802.11 are being increasingly deployed as a varied network of Mobile Ad-hoc Network (MANET) to provide users with extended coverage for wireless Internet access. HWAN, however, has a problem of too wide broadcasting of the Route Request (RREQ) in the route discovery of the Ad hoc Ondemand Distance Vector (AODV) protocol. In this paper, to enhance the performance of the AODV protocol, we have transformed it into a multipath protocol and proposed a new protocol that overcomes disadvantage of AODV by composing the neighbor table for overloaded RREQ. The neighbor table is provided in the form of metric using several items including the bandwidth. This can bring the localization effect of the nodes and we can expect a performance improvement by preventing an overloaded RREQ. Through the simulation, we could confirm better performance in packet loss rate, throughput, packet delivery ratio and routing overhead than the DSR protocol and AODV protocol.

6LoWPAN has become a new technology to provide the Internet connectivity to the traditional wireless sensor network (WSN). In order to route the delivered packet from originator to destination nodes, the simplified Ad-hoc On- Demand Distance Vector (AODV) routing protocol for 6LoWPAN with 6LoWPAN Ad-Hoc On-Demand Distance Vector Routing (LOAD) has been introduced. However, the conceptual LOAD routing protocol has yet proposed any path recovery mechanism in 6LoWPAN. In this paper, an originator recognition (OR) path recovery mechanism is proposed for the 6LoWPAN LOAD-based routing protocol. In this proposed mechanism, the participated nodes will memorize the originator address attached within data packet during the data transmission. When a link break happens on destination path, the LOAD protocol message will be amended by inserting an identity key, which is a memorial of originator address, in the generated route error (RERR) message before transmitted towards the originator for the failure notification. This identity key is then used by the originator to initialize path recovery in order to retransmit the failed data packet to the unreachable destination node. Instead of using MAC address in the LOAD routing protocol, IP address is used in the proposed Originator Recognition (OR) path recovery mechanism (OR-LOAD) routing protocol which is designed for the global routing. The proposed OR-LOAD routing protocol has been examined under noisy 6LoWPAN environment in Qualnet simulator. Its performance is then evaluated and compared to AODV routing protocol in terms of packet delivery ratio and average energy consumption. The simulation results show that the proposed OR-LOAD outperforms AODV with packet delivery ratio of 19.4%, and with comparable average energy consumption in both routing protocols.

Vehicular Ad Hoc Networks (VANET) are key to realizing Intelligent Transportation Systems (ITS). Although VANETs belong to the class of Mobile Ad Hoc Networks (MANET), and there are numerous routing protocols for MANETs, none of these protocols are applicable for VANETs. In particular, VANETs are highly dynamic due to high speed mobility of vehicles and traditional routing algorithms for MANETs cannot deal with such dynamicity of network nodes. Several comparative studies have suggested AODV (Ad hoc On-Demand Distance Vector), a well known MANET protocol that is adaptive to dynamic changes in network and makes efficient utilization of network resources, to be the best candidate for dealing with VANETs. However, verbatim adoption of AODV is not an efficient routing solution for VANETs. Recent works therefore proposed various modifications and/or additions to AODV to make it suitable for VANETs. It is particularly important to control congestion in VANETs by efficiently dealing with the AODV "Route Request" (RREQ) packets. In this paper, we propose Pro-AODV (Proactive AODV), a protocol that uses information from the AODV routing table to minimize congestion in VANETs, yet sustains other performance metrics at acceptable levels. The novelty and elegance in Pro-AODV comes from the fact that it does not require the execution of any additional logic, it is sufficient to know only the size of the routing table at each node.

With the rapid development of information technology and the increasing application of UAV in various fields, the security problems of unmanned aerial vehicle (UAV) communication network have become increasingly prominent. It has become an important scientific challenge to design a routing protocol that can provide efficient and reliable node to node packet transmission. In this paper, an efficient Digital Signature algorithm based on the elliptic curve cryptosystem is applied to routing protocol, and an improved security method suitable for on-demand routing protocol is proposed. The UAV communication network was simulated through the NS2 simulation platform, and the execution efficiency and safety of the improved routing protocol were analyzed. In the simulation experiment, the routing protocols of ad-hoc on demand distance vector (AODV), security ad-hoc on demand distance vector (SAODV), and improved security ad-hoc on demand distance vector (ISAODV) are compared in terms of the performance indicators of packet delivery rate, throughput, and end-to-end delay under normal conditions and when attacked by malicious nodes. The simulation results show that the improved routing protocol can effectively improve the security of the UAV communication network.