Two-hop Relay Algorithm Research Articles

Relay-Assisted Multicast With Markov Mobility

In this paper, we investigate the capacity and delay tradeoff under multicast scheme in the MANET, based on a general Markovian mobility model. To reduce the delay of the network, we propose a relay-assisted multicast scheme. Specifically, a two-hop relay algorithm is developed, in which Lyapunov drift is utilized to derive the average packet delay. In addition, we utilize the cache in relay nodes and propose the two-hop relay algorithm with redundancy. Theoretical analysis indicates that the network delay is significantly decreased, whereas the capacity remains the same. To guarantee the fairness and efficiency of the network, a two-hop relay selection algorithm with redundancy is proposed to decide which packet to serve in a queue. Moreover, the minimum energy function is applied to characterize the energy consumption of each node. We accordingly derive the accurate minimum energy function under the proposed relay-assisted multicast scheme. Furthermore, we design an efficient minimum energy algorithm, which pushes the actual energy consumption arbitrarily close to the minimum energy function at the cost of increasing delay. Theoretical results show that the optimal energy-delay tradeoff is achieved in our proposed algorithm. Numerous experiments are carried out to evaluate the performance of our proposed algorithms, where the experimental results well conform our theoretical findings.

On the packet delivery delay study for three-dimensional mobile ad hoc networks

This paper studies the packet delivery delay performance in three-dimensional mobile ad hoc networks (3D MANETs). Available work mainly focuses on the performance study in two-dimensional MANETs (2D MANETs), which cannot support delay-intensive applications in 3D MANETs. To explore the packet delivery delay performance in 3D MANETs, this paper adopts two-hop relay algorithm with packet replication for packet routing. With such an algorithm, source node can transmit a packet to at most f distinct relay nodes, which then help to forward the packet to its destination node. The algorithm is flexible such that the packet delivery process can be controlled through a proper setting of f. Specially, a general Markov chain theoretical framework is developed to model the packet delivery process under the algorithm in 3D MANETs. Based on the theoretical framework, the closed-form expressions are further derived for mean and relative standard deviation of packet delivery delay. Finally, extensive simulation and numerical results are provided to validate our theoretical models and illustrate the impact of network parameters on packet delivery delay performance in 3D MANETs.

Aging and inflammation in brain plasticity and repair

This paper studies the packet delivery delay performance in three-dimensional mobile ad hoc networks (3D MANETs). Available work mainly focuses on the performance study in two-dimensional MANETs (2D MANETs), which cannot support delay-intensive applications in 3D MANETs. To explore the packet delivery delay performance in 3D MANETs, this paper adopts two-hop relay algorithm with packet replication for packet routing. With such an algorithm, source node can transmit a packet to at most f distinct relay nodes, which then help to forward the packet to its destination node. The algorithm is flexible such that the packet delivery process can be controlled through a proper setting of f. Specially, a general Markov chain theoretical framework is developed to model the packet delivery process under the algorithm in 3D MANETs. Based on the theoretical framework, the closed-form expressions are further derived for mean and relative standard deviation of packet delivery delay. Finally, extensive simulation and numerical results are provided to validate our theoretical models and illustrate the impact of network parameters on packet delivery delay performance in 3D MANETs.

On the Delivery Likelihood of Two-Hop Relay MANETs using Erasure Cryptography

In this proposed method a new routing protocol is SelfAdaptive on demand Geographic routing protocols. One of the distinctive features has provide reliable and energy efficient feature to existing schemes in order to increase the lifetime of the network and reduces control overhead compute up to the proactive schemes which provides reliable routing at the same time with a lesser amount of energy utilization. We are embedding optimization (Marko chain algorithm) on the delivery probability performance in a two-hop relay algorithm with erasure coding. The erasure coding used for the message that is erasure coded into multiple frames at source node. Also we developed finite-state Markov chain model to characterize the complicated message delivery process in the MANETs. Based on the above model, closed-form expressions are further derived for the corresponding message delivery probability under any given message lifetime and message size. The above concept is verified through simulation studies, which can be used to accurately predict the message delivery probability behavior and characterize its relationship with the message size.

Generalized Two-Hop Relay for Flexible Delay Control in MANETs

The available two-hop relay protocols with out-of-order or strictly in-order reception cannot provide a flexible control for the packet delivery delay, which may significantly limit their applications to the future mobile ad hoc networks (MANETs) with different delay requirements. This paper extends the conventional two-hop relay and proposes a general group-based two-hop relay algorithm with packet redundancy. In such an algorithm with packet redundancy limit $f$ and group size $g$ (2HR- $(f,g)$ for short), each packet is delivered to at most $f$ distinct relay nodes and can be accepted by its destination if it is a fresh packet to the destination and also it is among $g$ packets of the group the destination is currently requesting. The 2HR- $(f,g)$ covers the available two-hop relay protocols as special cases, like the in-order reception ones $(f\geq 1,g=1)$ , the out-of-order reception ones with redundancy $(f>1,g=\infty)$ , or without redundancy $(f=1,g=\infty)$ . A Markov chain-based theoretical framework is further developed to analyze how the mean value and variance of packet delivery delay vary with the parameters $f$ and $g$ , where the important medium contention, interference, and traffic contention issues are carefully incorporated into the analysis. Extensive simulation and theoretical results are provided to illustrate the performance of the 2HR- $(f,g)$ algorithm and the corresponding theoretical framework, which indicate that the theoretical framework is efficient in delay analysis and the new 2HR- $(f,g)$ algorithm actually enables both the mean value and variance of packet delivery delay to be flexibly controlled in a large region.

MONET Special Half-Issue “Recent Advances on Communications and Networking in China”

Editorial: This special issue features extended versions of six of the best papers selected from the conference Chinacom 2011, which was held in Harbin, China, on August 17– 19, 2011. The emerging vehicular networks are targeted to provide efficient communications between mobile vehicles and fixed roadside units (RSU), and support mobile multimedia applications and safety services with diverse quality of service (QoS) requirements. In the paper titled “Medium Access Control for QoS Provisioning in Vehicle-to-Infrastructure Communication Networks”, Bi, Cai, Shen and Zhao propose a busy tone based medium access control (MAC) protocol with enhanced QoS provisioning for life critical safety services. By using busy tone signals for efficient channel preemption in both contention period (CP) and contention free period (CFP), emergency users can access the wireless channel with strict priority when they compete with multimedia users, and thus achieve the minimal access delay. Furthermore, through efficient transmission coordination on the busy tone channel, contention level can be effectively reduced, and the overall network resource utilization can be improved accordingly. The authors develop an analytical model to quantify the medium access delay of emergency messages. Extensive simulations with Network Simulator (NS)-2 validate the analysis and demonstrate that the proposed MAC can guarantee reliable and timely emergency message dissemination in a vehicular network. Delay tolerant networks (DTNs) rely on the mobility of nodes and sequences of their contacts to compensate for lack of continuous connectivity and thus enable messages to be delivered from end to end in a “store-carryforward” way, where multiple relay nodes are usually employed in the message delivery process. In the paper “Performance Modeling for Relay Cooperation in Delay Tolerant Networks Layered Fault”, Liu, Jiang, Nishiyama and Kato focus on such relay cooperation and analytically explore its impact on the delivery performance in DTNs. Specifically, the authors first develop a continuous time Markov chain-based theoretical framework to model the complicated message delivery process in delay tolerant networks adopting the two-hop relay algorithm. They then derive closed-form expressions for both the expected V. C. M. Leung (*) Department of Electrical and Computer Engineering, University of British Columbia (UBC), Vancouver, Canada e-mail: vleung@ece.ubc.ca

Capacity and Delay of Probing-Based Two-Hop Relay in MANETs

Due to their simplicity and efficiency, the two-hop relay algorithm and its variants serve as a class of attractive routing schemes for mobile ad hoc networks (MANETs). With the available two-hop relay schemes, a node, whenever getting an opportunity for transmission, randomly probes only once a neighbor node for the possible transmission. It is notable that such single probing strategy, although simple, may result in a significant waste of the precious transmission opportunities in highly dynamic MANETs. To alleviate such limitation for a more efficient utilization of limited wireless bandwidth, this paper proposes a more general probing-based two-hop relay algorithm with limited packet redundancy. In such an algorithm with probing round limit τ and packet redundancy limit f, each transmitter is allowed to conduct up to τ rounds of probing for identifying a possible receiver and each packet can be delivered to at most f distinct relays. A general theoretical framework is further developed to help us understand that under different setting of τ and f, how we can benefit from multiple probings in terms of the per node throughput capacity and the expected end-to-end packet delay.

Performance Modeling for Relay Cooperation in Delay Tolerant Networks

Delay tolerant networks (DTNs) rely on the mobility of nodes and sequences of their contacts to compensate for lack of continuous connectivity and thus enable messages to be delivered from end to end in a "store-carry-forward" way, where multiple relay nodes are usually employed in the message delivery process. In this paper, we focus on such relay cooperation and analytically explore its impact on the delivery performance in DTNs. Specifically, we first develop a continuous time Markov chain-based theoretical framework to model the complicated message delivery process in delay tolerant networks adopting the two-hop relay algorithm. We then derive closed-form expressions for both the expected delivery delay and the corresponding expected delivery cost, where the important relay behaviors of forwarding traffic for itself or for other nodes are carefully incorporated into the analysis.

Delay and Capacity in Ad Hoc Mobile Networks with f-cast Relay Algorithms

The two-hop relay algorithm and its variants have been attractive for ad hoc mobile networks, because they are simple yet efficient, and more importantly, they enable the capacity and delay to be studied analytically. This paper considers a general two-hop relay with f-cast (2HR-f), where each packet is delivered to at most f distinct relay nodes and should be received in order at its destination. We derive the closed-form theoretical models rather than order sense ones for the 2HR-f algorithm with a careful consideration of the important interference, medium contention, traffic contention and queuing delay issues, which enable an accurate delay and capacity analysis to be performed for an ad hoc mobile network employing the 2HR-f. Based on our models, one can directly get the corresponding order sense results. Extensive simulation studies are also conducted to demonstrate the efficiency of these new models.

Latency-aware and energy efficiency tradeoffs for wireless sensor networks

Latency and energy efficiency are two important parameters to evaluate the Wireless Sensor Networks (WSNs). To reduce delays in the WSN, the sensor node will send out redundant packets. Suppose the WSN has a cell-partitioned structure and the two-hop relay algorithm is adopted, the relay/destination nodes selection will determine the networks performance. The FLS is applied to the nodes selection. In contrast with the cases that only consider one descriptor, the FLS application can manage the delay/energy tradeoffs to meet the network performance requirements. Another work discussed is packets transmission in WSNs. We proposed FLS in the optimisation of SIR threshold selection. Average delay and distance of a node to the source node are selected as antecedents for the FLS. The output of FLS provided adjusting factors for the SIR threshold. Simulation results showed the fuzzy optimisation could achieve a better network efficiency, reduce the average delay and extend the network lifetime.

Capacity and Delay Tradeoffs for Ad Hoc Mobile Networks

We consider the throughput/delay tradeoffs for scheduling data transmissions in a mobile ad hoc network. To reduce delays in the network, each user sends redundant packets along multiple paths to the destination. Assuming the network has a cell partitioned structure and users move according to a simplified independent and identically distributed (i.i.d.) mobility model, we compute the exact network capacity and the exact end-to-end queueing delay when no redundancy is used. The capacity-achieving algorithm is a modified version of the Grossglauser-Tse two-hop relay algorithm and provides O(N) delay (where N is the number of users). We then show that redundancy cannot increase capacity, but can significantly improve delay. The following necessary tradeoff is established: delay/rate/spl ges/O(N). Two protocols that use redundancy and operate near the boundary of this curve are developed, with delays of O(/spl radic/N) and O(log(N)), respectively. Networks with non-i.i.d. mobility are also considered and shown through simulation to closely match the performance of i.i.d. systems in the O(/spl radic/N) delay regime.