Multihop Packet Radio Networks Research Articles

A Survey of Topology-Transparent Scheduling Schemes in Multi-Hop Packet Radio Networks

The aim of topology-transparent scheduling in multi-hop packet radio networks is to find a schedule for the nodes in such a way that the schedule of the existing nodes need not be recomputed when the network topology changes. It caters to highly dynamic scenarios where topology changes occur faster than the speed at which schedule updates can be orchestrated. Hence, the scheduler is typically expected to use only global network parameters like upper bounds on the number of nodes in the network and on the maximum degree of any node in the network. The problem is non-trivial if there are restrictions on the frame length or the minimum throughput of a node in a frame. Over the years, several innovative solutions have been proposed using a variety of mathematical techniques. We present a lucid tutorial-style survey of the approaches using an integrative taxonomy and a comparative analysis. We also outline a few directions for future research in the field.

Trust Factor Based Secure Congestion Control For Vanet

Weight-based clustering algorithm in ad hoc network is an on demand clustering algorithm for multi-hop packet radio network. These types of networks are ad hoc networks and dynamic in nature due to mobility of nodes. Clustering in mobile ad hoc network can be defined as various partitions into various groups. It is an important concept of VANNET, because clustering makes it possible to guarantee of system performance, such as throughput delay and also security issues. So in the algorithm they select the cluster head whose performance is well and formation of cluster in ad hoc network. The cluster head is elected based on weight factor, so it is called weighted clustering algorithm. Weighted clustering algorithm is basically appropriate cluster selection in wireless adhoc network where it is necessary to provide robustness in face of topological changes caused by node motion, node failure and node insertion or node removal. The WCA select the cluster head which has lowest weight among the nodes and some other factor also consider the election for cluster head. The cluster head, form a dominant set in the network, determine the topology and its stability. The weighted clustering algorithm takes into consideration the ideal degree, transmission power, mobility and battery power of nodes. Traffic efficiency applications are becoming increasingly popular over the road networks in the last few years. This type of applications aims mainly at increasing the traffic fluency over the road network, which minimizes the travel time of each vehicle towards its targeted destinations. The Vehicular Ad-Hoc Networks (VANETs) technology has been utilized to design these applications. Communications between vehicles, V2V, and between vehicles and installed Road Side Units (RSUs), V2I, helped designing these applications. Malicious, selfish and intruder drivers can take advantages of other cooperative drivers and use their trust. a Secure Congestion control protocol. This protocol aims to guarantee integrity and authenticity of transmitted data. It is designed to provide the security requirements of traffic efficiency protocols that have been proposed using the technology of VANETs. SCOOL also aims to preserve the privacy of the cooperative vehicles and drivers. The main contribution of work is new strategy for clustering a wireless ad hoc network and improvement in WCA. Author derived a simple stability model and a load balancing clustering scheme. They showed that the algorithm outperform in term of cluster formation and stability. Main idea of approach is to avoid cluster re-election and reduce the computation and communication cost. The improved weighted clustering algorithm, the goals of algorithm are maintaining stable clustering structure, minimizing the overhead for clustering set up, maximize lifetime of nodes in the system and achieving good performance. Keyword - Weight-based clustering, SCOOL, WCA, VANETs.

A Proposed Model for Load Balancing in MANET

is a multi-cluster, multi-hop packet radio network that should adapt itself to the dynamically changing network configurations. This dynamic reconfiguration is governed by clusterheads, a major set of nodes that have enough resources to be capable of routing packets in the network. This paper proposes a load balancing heuristic to extend the network lifetime. It has two phases. Initial clustering is done for the entire network in start up phase that takes node's degree and energy as input parameters. The maintenance phase keeps the network topology updated through global re-clustering and local updation. Global reclustering is initiated when the network becomes significantly unbalanced i.e. if the variance of degree of the cluster heads in the network is greater than a pre-determined threshold. It is expected to get better result than the time driven algorithms, as implementation is still under progress. Keywords-Hoc networks, Clustering, Load Balancing, Reclustering, Energy Conservation

Comparative Analysis of Architectures for Intrusion Detection Systems against DoS Attacks in MANETs based on Chi-Square Test

A Mobile Adhoc Network (MANET) is a group of wireless nodes that can be dynamically organized as a multi-hop packet radio network without using any existing infrastructure or centralized administration. MANETs are susceptible to the variety of attacks that threaten their operation and the provided services. MANET is severely affected by Denial of Service (DoS) attacks which become a problem for internet users. Intrusion Detection System (IDS) may act as defensive mechanism which monitors network activities in order to detect malicious activities performed by intruders and initiate proper response to malicious activity. Several IDS architectures are proposed for detecting the malicious node. In this paper the following IDS architectures for DoS attack in MANET are compared based on Chi-Square test: i)Stand-alone ii)Cooperative iii)Hierarchical iv)Zone based approach using mobile agent. Also listed out the strengths and weaknesses of each IDS architecture. A cluster based cooperative and distributed IDS which uses multiple light weight agents and reduces the overhead of cluster head is proposed. Simulations based on NS2 are as shown.

On the distributed construction of a collision-free schedule in multi-hop packet radio networks

This paper introduces a protocol that distributively constructs a collision-free schedule for multi-hop packet radio networks in the presence of hidden terminals. As a preliminary step, each wireless station computes the schedule length after gathering information about the number of flows in its neighbourhood. Then, a combination of deterministic and random backoffs are used to reach a collision-free schedule. A deterministic backoff is used after successful transmissions and a random backoff is used otherwise. It is explained that the short acknowledgement control packets can easily result in channel time fragmentation and, to avoid this, the use of link layer delayed acknowledgements is advocated and implemented. The performance results show that a collision-free protocol easily outperforms a collision-prone protocol such as Aloha. The time that is required for the network to converge to a collision-free schedule is assessed by means of simulation.

Distance-based node activation for geographic transmissions in fading channels

In wireless multi-hop packet radio networks (MPRNs) that employ geographic transmissions, sleep schedules or node activation techniques may be used to power off some nodes to conserve energy. We consider the problem of selecting which nodes should power on to listen to a scheduled transmission when the channel suffers from random fading. We choose the objective of maximizing the expected value of the distance covered in a single transmission between a transmitter and the farthest receiver that successfully receives the packet, under a constraint on the expected number of receivers that turn on. Since there is a tradeoff between the distance of a node from the transmitter and the probability that the node receives the message correctly, we propose to use node-activation based on link-distance (NA-BOLD). We investigate optimal and sub-optimal NA-BOLD schemes and compare their performance with that of schemes that use a constant sleep schedule for every node within some radius of the transmitter. Our results show that the proposed NA-BOLD schemes achieve significantly larger transmission distances than conventional schemes.

A Dynamic Clustering Algorithm for MANETs by modifying Weighted Clustering Algorithm with Mobility Prediction

The multi hop packet radio networks also named mobile ad-hoc networks (MANETs) have a dynamic topology due to the mobility of their nodes. A notable amount of energy is utilized every time a signal is sent and received by a mobile node. Many such signals and power are wasted to update the positional information of the nodes in a wireless scenario. Further bandwidth is also wasted by sending control signals rather than using it effectively for data communication. To minimize this utilization, we propose a modified algorithm that uses Weighted Clustering Algorithm (WCA) for cluster formation and Mobility Prediction for cluster maintenance. Clustering is an effective technique for node management in a MANET. Cluster formation involves election of a mobile node as Cluster head and it controls the other nodes in the newly formed cluster. The connections between nodes and the cluster head changes rapidly in a mobile ad-hoc network. Thus cluster maintenance is also essential. Prediction of mobility based cluster maintenance involves the process of finding out the next position that a mobile node might take based on the previous locations it visited. In this paper we propose to reduce the overhead in communication by predicting mobility of node using linear auto regression and cluster formation.

Adaptive modulation in ad hoc DS/CDMA packet radio networks

This paper investigates the benefit of adaptive modulation based on channel state information (CSI) in direct-sequence/ code-division multiple-access (DS/CDMA) multihop packet radio networks. By exploiting varying channel conditions, adaptive modulation can be used in ad hoc networks to provide upper layers with higher capacity links over which to relay traffic. Using the /spl alpha/-stable interference model, the distribution of the signal-to-interference ratio (SIR) is obtained for a slotted system of randomly, uniformly distributed nodes using multilevel coherent modulation schemes. Performance is evaluated in terms of the information efficiency, which is a new progress-related measure for multihop networks. Three types of adaptivity are analyzed, differing in the level of CSI available: 1) full knowledge of the SIR at the receiver; 2) knowledge of only the signal attenuation due to fading; and 3) knowledge of only the slow fading component of the signal attenuation. The effect of imperfect channel information is also investigated. Sample results are given for interference-limited networks experiencing fourth-power path loss with distance, Ricean fading, and lognormal shadowing.

Information efficiency of multihop packet radio networks with channel-adaptive routing

This paper analyzes the benefit of adaptive routing based on knowledge of the channel state information in multihop, ad hoc wireless networks that use direct-sequence code-division multiple access. Cross-layer, channel-adaptive routing exploits the inherent spatial diversity of multihop wireless networks to select links with favorable channel conditions. The information efficiency, an extension of a previously used measure called expected progress, is used to evaluate performance. Results show that, combined with adaptive modulation, adaptive routing can improve performance in ad hoc networks by a factor of four to five in channels with Rayleigh fading and lognormal shadowing. The lack of position information in the routing decision would reduce performance by 25%. New approaches to channel-adaptive routing that enable rapid adaptivity to channel conditions are discussed.

Information efficiency of multihop packet radio networks with channel-adaptive routing

Information efficiency of multihop packet radio networks with channel-adaptive routing

Topology-transparent time division multiple access broadcast scheduling in multihop packet radio networks

Many topology-dependent transmission scheduling algorithms have been proposed to minimize the time-division multiple-access frame length in multihop packet radio networks (MPRNs), in which changes of the topology inevitably require recomputation of the schedules. The need for constant adaptation of schedules-to-mobile topology entails significant problems, especially in highly dynamic mobile environments. Hence, topology-transparent scheduling algorithms have been proposed, which utilize Galois field theory and Latin squares theory. We discuss the topology-transparent broadcast scheduling design for MPRNs. For single-channel networks, we propose the modified Galois field design (MGD) and the Latin square design (LSD) for topology-transparent broadcast scheduling. The MGD obtains much smaller minimum frame length (MFL) than the existing scheme while the LSD can even achieve possible performance gain when compared with the MGD, under certain conditions. Moreover, the inner relationship between scheduling designs based on different theories is revealed and proved, which provides valuable insight. For topology-transparent broadcast scheduling in multichannel networks, in which little research has been done, the proposed multichannel Galois field design (MCGD) can reduce the MFL approximately M times, as compared with the MGD when M channels are available. Numerical results show that the proposed algorithms outperform existing algorithms in achieving a smaller MFL.

Optimizing information efficiency in a direct-sequence mobile packet radio network

We consider a direct-sequence multihop packet radio network using slotted ALOHA in a Rayleigh fading environment. We are interested in optimally choosing the transmission range, code rate, and slotted ALOHA transmission probability to be used by each node. We use a new performance measure, information efficiency, to analyze the network and show that the information efficiency of the low-cost mobile packet radio network can be improved approximately 20 fold by using the optimum parameters. We suggest a practical trellis-coded modulation scheme which comes close to realizing the theoretic limits found.

WCA: A Weighted Clustering Algorithm for Mobile Ad Hoc Networks

In this paper, we propose an on-demand distributed clustering algorithm for multi-hop packet radio networks. These types of networks, also known as i>ad hoc networks, are dynamic in nature due to the mobility of nodes. The association and dissociation of nodes to and from i>clusters perturb the stability of the network topology, and hence a reconfiguration of the system is often unavoidable. However, it is vital to keep the topology stable as long as possible. The i>clusterheads, form a i>dominant set in the network, determine the topology and its stability. The proposed weight-based distributed clustering algorithm takes into consideration the ideal degree, transmission power, mobility, and battery power of mobile nodes. The time required to identify the clusterheads depends on the diameter of the underlying graph. We try to keep the number of nodes in a cluster around a pre-defined threshold to facilitate the optimal operation of the medium access control (MAC) protocol. The non-periodic procedure for clusterhead election is invoked on-demand, and is aimed to reduce the computation and communication costs. The clusterheads, operating in “dual" power mode, connects the clusters which help in routing messages from a node to any other node. We observe a trade-off between the uniformity of the load handled by the clusterheads and the connectivity of the network. Simulation experiments are conducted to evaluate the performance of our algorithm in terms of the number of clusterheads, i>reaffiliation frequency, and dominant set updates. Results show that our algorithm performs better than existing ones and is also tunable to different kinds of network conditions.

Selection diversity forwarding in a multihop packet radio network with fading channel and capture

Recent and increased interest of wireless mobile ad hoc networking motivates detailed examination of routing schemes specifically targeted for the demanding constraints that an unreliable, time varying and broadcast like wireless medium imposes. Incorporation and exploitation of radio characteristics are fundamental keys to successful and near optimal operation of routing schemes in a wireless environment. In this paper, forwarding methods for wireless mobile multihop networking in Rayleigh fading and non-fading channels are examined. An adaptive forwarding scheme denoted Selection Diversity Forwarding (SDF) is introduced and compared with two classical forwarding methods. It is shown that SDF presents significant performance improvements. In particular and in contrast to the reference methods NFP and MFR, the performance of SDF is enhanced under fading channel conditions. It is found that local path adaptation has potential to perform better than routing approaches along a single path.

Transmission-efficient routing in wireless networks using link-state information

The efficiency with which the routing protocol of a multihop packet-radio network uses transmission bandwidth is critical to the ability of the network nodes to conserve energy. We present and verify the source-tree adaptive routing (STAR) protocol, which we show through simulation experiments to be far more efficient than both table-driven and on-demand routing protocols proposed for wireless networks in the recent past. A router in STAR communicates to its neighbors the parameters of its source routing tree, which consists of each link that the router needs to reach every destination. To conserve transmission bandwidth and energy, a router transmits changes to its source routing tree only when the router detects new destinations, the possibility of looping, ot the possibility of node failures or network partitions. Simulation results show that STAR is an order of magnitude more efficient than any topology-broadcast protocol proposed to date and depending on the scenario is up to six times more efficient than the Dynamic Source Routing (DSR) protocol, which has been shown to be one of the best performing on-demand routing protocols.

Power consumption in packet radio networks

In this paper we study the problem of assigning transmission ranges to the nodes of a multi-hop packet radio network so as to minimize the total power consumed under the constraint that adequate power is provided to the nodes to ensure that the network is strongly connected (i.e., each node can communicate along some path in the network to every other node). Such assignment of transmission ranges is called complete. We also consider the problem of achieving strongly connected bounded diameter networks. For the case of n+1 colinear points at unit distance apart (the unit chain) we give a tight asymptotic bound for the minimum cost of a range assignment of diameter h when h is a fixed constant and when h⩾(1+ε) log n , for some constant ε>0. When the distances between the colinear points are arbitrary, we give an O(n 4) time dynamic programming algorithm for finding a minimum cost complete range assignment. For points in three dimensions we show that the problem of deciding whether a complete range assignment of a given cost exists, is NP-hard. For the same problem we give an O(n 2) time approximation algorithm which provides a complete range assignment with cost within a factor of two of the minimum. The complexity of this problem in two dimensions remains open, while the approximation algorithm works in this case as well.

Optimal transmission ranges and code rates for frequency-hop packet radio networks

We consider a frequency-hopping multihop packet radio network using M-ary frequency-shift keying modulation in a Rayleigh fading environment. Each node transmits packets using an extended (n, k) Reed-Solomon code and the slotted ALOHA channel access protocol. For this network, we determine the optimum transmission range, optimum code rate, and optimum slotted ALOHA transmission probability to be used by each node in the network. Tradeoffs in choosing the transmission range and code rate, and the spectral efficiency of the network are captured in a new performance measure, information efficiency, which is analogous to expected forward progress. Maximizing the information efficiency yields the optimum desired network parameters.

Diversity reception in a multihop packet radio network

The performance improvement which results from the use of multiple antennas at each node in a multihop packet radio network is examined. Four transmission strategies based on three previously proposed routing schemes and one new routing scheme, MTP, are studied. It is found that the use of two antennas can improve the performance of all four transmission strategies by about 25% in a Rayleigh fading environment. The transmission strategy based on the MTP routing scheme is shown to be generally superior to those based on the other three routing schemes.

TDMA scheduling design of multihop packet radio networks based on latin squares

Many transmission scheduling algorithms have been proposed to maximize spatial reuse and minimize the time division multiple access (TDMA) frame length in multihop packet radio networks. Almost all existing algorithms assume exact network topology information and require recomputations when the network topology changes. In addition, existing work focuses on single channel TDMA systems. In this paper, we propose a multichannel topology-transparent algorithm based on latin squares. The proposed algorithm has the flexibility to allow the growth of the network, i.e., the network can add more mobile nodes without recomputation of transmission schedules for existing nodes. At the same time, a minimum throughput is guaranteed. We analyze the efficiency of this algorithm and examine the topology-transparent characteristics and the sensitivity on design parameters by analytical and simulation techniques.

An optimal topology-transparent scheduling method in multihop packet radio networks

Many transmission scheduling algorithms have been proposed to maximize the spatial reuse and minimize the time-division multiple-access (TDMA) frame length in multihop packet radio networks. Almost all existing algorithms assume exact network topology information and do not adapt to different traffic requirements. Chlamtac and Farago (1994) proposed a topology-transparent algorithm. Following their approach, but with a different design strategy, we propose another algorithm which is optimal in that it maximizes the minimum throughput. We compare our algorithm with that of Chlamtac and Farago's and with the TDMA algorithm, and find that it gives better performance in terms of minimum throughput and minimum and maximum delay times. Our algorithm requires estimated values of the number of nodes and the maximum nodal degree in the network. However, we show that the performance of our algorithm is insensitive to these design parameters.