scholarly journals Dynamic Retransmission Limit Scheme in MAC Layer for Routing in Multihop Ad hoc Networks

2008 ◽  
Vol 2008 ◽  
pp. 1-17 ◽  
Author(s):  
Ralph El-Khoury ◽  
Rachid El-Azouzi

We consider a wireless ad hoc network with random access channel. We present a model that takes into account topology, routing, random access in MAC layer, and forwarding probability. In this paper, we focus on drawing benefit from the interaction of the MAC (governed by IEEE 802.11 or slotted Aloha) and routing by defining a new cross-layer scheme for routing based on the limit number of retransmission. By adjusting dynamically and judiciously this parameter in a saturated network, we have realized that both stability of forwarding queues and average throughput are significantly improved in linear networks with symmetric traffic: a gain of 100% can be reached. While in asymmetric topology network with asymmetric traffic, we achieve a better average delay (resp., throughput) for each connection without changing the average throughput (resp., delay). In addition, we show the efficiency of our new scheme in case of multimedia applications with delay constraint. A detailed performance study is presented using analytical and simulation evaluation.

Author(s):  
Priyanka Bharadwaj ◽  
Surjeet Balhara

Background & Objective: There are some challenging issues such as providing Quality of Service (QoS), restricted usage of channels and shared bandwidth pertaining to ad-hoc networks in a dynamic topology. Hence, there is a requirement to support QoS for the application environment and multimedia services in ad-hoc networks with the fast growing and emerging development of information technology. Eventually, bandwidth is one of the key elements to be considered. Methods: Energy aware QoS routing protocol in an ad-hoc network is presented in this article. Results and Conclusion: The simulation results indicate that the improved protocol outperforms Adhoc On-Demand Distance Vector (AODV) routing protocol in terms of QoS metric such as throughput, packet delivery ratio, loss rate and average delay.


2012 ◽  
Vol 50 (5) ◽  
pp. 192-200 ◽  
Author(s):  
Razvan Stanica ◽  
Emmanuel Chaput ◽  
Andre-Luc Beylot

2016 ◽  
Vol 109 ◽  
pp. 50-66 ◽  
Author(s):  
Suman Bhunia ◽  
Vahid Behzadan ◽  
Paulo Alexandre Regis ◽  
Shamik Sengupta

Author(s):  
TEJAL ARVIND SONAWALE ◽  
SHIKHA NEMA

Ad Hoc Networks face a lot of problems due to issues like mobility, power level, load of the network, bandwidth constraints, dynamic topology which lead to link breaks, node break down and increase in overhead. As nodes are changing their position consistently, routes are rapidly being disturbed, thereby generating route errors and new route discoveries. The need for mobility awareness is widely proclaimed. In our dissertation we present a scheme AOMDV-APLP that makes AOMDV aware of accessibility of neighbor nodes in the network. Nodes acquire the accessibility information of other nodes through routine routing operations and keep in their routing table. Based on this information route discovery is restricted to only “accessible” and “start” nodes. Further route with the strongest signal strength is selected from multiple routes using Link life value predicted by Link Breakage prediction technique. Simulation result shows that using accessibility and link life knowledge in route discovery process MAC overhead, routing overhead and average delay is reduced 3 times, and improve the Packet delivery ratio to a large extent than standard AOMDV which reflects effective use of network resources.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 643
Author(s):  
Muhammad Bilal Latif ◽  
Feng Liu ◽  
Kai Liu

An autonomous driving environment poses a very stringent requirement for the timely delivery of safety messages in vehicular ad hoc networks (VANETs). Time division multiple access (TDMA)-based medium access control (MAC) protocols are considered a promising solution because of their time-bound message delivery. However, in the event of mobility-caused packet collisions, they may experience an unpredicted and extended delay in delivering messages, which can cause catastrophic accidents. To solve this problem, a distributed TDMA-based MAC protocol with mobility-caused collision mitigation (MCCM-MAC) is presented in this paper. The protocol uses a novel mechanism to detect merging collisions and mitigates them by avoiding subsequent access collisions. One vehicle in the merging collisions retains the time slot, and the others release the slot. The common neighboring vehicles can timely suggest a suitable new time slot for the vacating vehicles, which can avoid access collisions between their packet transmissions. A tie-breakup mechanism is employed to avoid further access collisions. Simulation results show that the proposed protocol reduces packet loss more than the existing methods. Consequently, the average delay between the successfully delivered periodic messages is also reduced.


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