Mahadev A. Gawas

Cross Layer Best effort QoS aware routing protocol for Ad Hoc Network

Mobile Ad Hoc Networks (MANETs) are a self organizing and adaptive wireless networks. Currently MANETs possess an advanced challenge in providing Quality of Service( QoS) support for real time application data streaming through the network. These applications are delay sensitive and get affected due to congestion in the network. Thus, performance degrades due to high data loss, frequent link breakage and excessive retransmission. The strict layered network structure makes even more difficult to provide solutions for such issues. We propose a protocol which cooperates between adjacent layers and performs cross layer communication. We propose a novel QoS routing for MANET called Cross Layer Best effort QoS aware routing protocol (CLBQ) which considers the metric of link quality, data rates and MAC delay as the QoS parameters. The proposed protocol implements cross layer interaction between PHY, MAC and Network layer. The simulation results conducted shows best effort QoS service to the network in discovering the route and data transfer. Our analysis shows that the protocol has improved throughput and low network overhead.

Cross layered adaptive cooperative routing mode in mobile ad hoc networks

A Cooperative communication technique has gained considerable attention in the recent time to improve the quality of service (QoS) of ad hoc networks. Cooperative communication significantly improves link capacity through physical layer technique, and spatial diversity gain is achieved by using neighboring nodes to retransmit the overheard information to the intended destination node. However, upper layer protocols are not elegantly designed to adequately exploit the spatial diversity to improve overall network performance in ad hoc networks. Limiting the cooperation to one network layer may not be the best solution. Thus, in this paper, we intend to achieve multilayer functionality from physical layer to the routing layer to provide cooperative communication. An adaptive cross layered cooperative routing algorithm (ACCR) is proposed to analyze the channel state variations and selectively choose the cooperative MAC scheme on demand by exploiting spatial diversity. The algorithm dynamically selects best relay candidates based on QoS metric, contention delay and node energy fairness. Network layer, then chooses an optimized path from source to destination through the selected relay nodes. We validate the algorithm with extensive simulations. The results clearly show that cooperative cross-layer design approach effectively improves the average throughput and average delay for each packet transmission.

Cross layer approach for efficient dissemination of emergency messages in VANETs

This paper proposes a cross layer approach for efficient dissemination of emergency messages in VANETs (CL-DEM) by minimizing the message redundancy and maintaining low end-to-end communication delays. We propose a scheme to select a one-hop neighbor relay as a potential forwarder for relaying the broadcast messages to improve the transmission reliability in a platoon of vehicles. The relay selection metrics compose of vehicular density, vehicular velocity, and the geographical location. The selected relay controls the broadcast messages with minimum overhead and with minimum bandwidth consumption. To provide the service differentiation to different traffic classes, we adopt 802.11e MAC. The cross layer is further extended to the transport layer to dynamically adapt the data transmission rate based on the physical channel state. The extensive simulation analysis conducted reveals that the proposed cross-layer scheme effectively propagates the critical broadcast messages with minimum latency.

Cross layer adaptive congestion control for best-effort traffic of IEEE 802.11e in mobile ad hoc networks

The dominance of multimedia traffic over the Internet, coupled with the rising number of applications of MANETs, has made Quality of Service (QoS) a major concern. The IEEE 802.11e standard enhanced distributed channel access(EDCA) has been proposed as an enhancement of 802.11 standard, which provides QoS at MAC layer with a service differentiation scheme for high priority traffic. But IEEE 802.11e has not adequately addressed the issue of handling best effort traffic data flows through contention-based networks which in turn results in TCP performance degradation. To enhance the best effort traffic performance in 802.11e with high-quality of service to maximize the system throughput, we propose a novel scheme called, Adaptive Best Effort Traffic Scheduler for EDCA(ABET-EDCA). In this scheme, TCP packets get prioritized by dynamically adapting to contention window parameters. In addition to this, traffic class monitors the MAC queue and computes TXOP limits value at runtime. This results in reduced delay and loss factor. Additionally, we incorporate the cross layer approach by exploiting the physical and MAC layer information to initiate corrective measures at the Transport and Network layer to enhance best effort traffic performance. The simulation conducted shows the significant improvement in TCP performance in terms of goodput, delay and throughput even under high loads compared to EDCA.

Cross layer approach for effective multi hop broadcast in VANET

Cooperative communication in VANET has become the de-facto in enabling technology to improve safety and efficiency on inter-vehicle communication (IVC). The safety related messages broadcast on emergency must have a minimum delay and high reliability. This paper proposes a cross-layer approach to efficiently broadcast the safety messages by minimizing the message redundancy and maintaining low end-to-end communication delays. We propose a scheme to select a one-hop neighbor relay as a potential forwarder for relaying the broadcast messages to improve the transmission reliability in a platoon of vehicles. The relay selection metrics compose of vehicular density, velocity, and the geographical location. The selected relay controls the broadcast messages with minimum overhead and with minimum bandwidth consumption. Similarly, a multimedia emergency message needs high priority with a shorter transmission delay. To provide the service differentiation to different traffic classes, we adopt 802.11e MAC. The cross layer is further extended to the transport layer to dynamically adapt the data transmission rate based on the physical channel state. The extensive simulation analysis conducted reveals that the proposed cross-layer scheme effectively propagates the critical broadcast messages with lesser packet latency and higher packet delivery ratio.

AMCCR: Adaptive Multi-QoS Cross-Layer Cooperative Routing in Ad Hoc Networks

The cooperative communication technique in an ad hoc network exploits the spatial diversity gains inherent in multiuser systems and mitigates the multipath fading. This technique is necessary but perhaps not sufficient to meet the QoS demands in ad hoc network. This is due to the fact that routing protocol at the network layer is more responsible for the successful packet delivery and QoS support. In this paper, we propose an adaptive multi-QoS cross-layer cooperative routing (AMCCR) protocol that enhances the performance through the cooperation of physical, MAC, and network layers. We first formulate an approach to analyze the channel state variations for effective communication schemes at the physical layer. Secondly, we dynamically select the transmission mode to employ cooperative MAC scheme by exploiting spatial diversity. Thereafter, the network layer chooses an optimized route from source to destination through the selected best relay candidates based on multiple QoS metrics. The paper is further extended to support dual-hop half-duplex communication via selected relay by coding technique. The proposed protocol is validated by extensive simulations and compared with CD-MAC and CODE protocols. The results clearly show that the proposed cooperative cross-layer design approach significantly improves the average delay, throughput, and network lifetime of the system.

Cross layer multi QoS metric routing for multimedia traffic in 802.11E over MANETs

To support QoS for a multimedia traffic, IEEE 802.11e standard Enhanced distributed channel access (EDCA) has been proposed. However, the EDCA is more focused on providing quality of service(QoS) solution at the MAC layer, which is necessary, but perhaps not sufficient as the layered TCP stack architecture does not satisfy the QoS demands in ad hoc network. This is due to the fact that routing protocol is responsible for the successful packet delivery and QoS Support. The conventional single scalar routing protocols are not suitable for high traffic QoS sensitive multimedia traffic load on Mobile ad Hoc Networks (MANETs). The paper proposes a Cross layer Multimetric link disjoint Multipath Routing (CMMR) protocol based on distinct QoS constraints. The paper uses cross-layer communications to consider multiple layer metrics like MAC queue utilization, node density degree, and mobility factor to achieve channel state awareness and keep the up to date status of the route in terms of QOS proficiency at each intermediate node. The proposed algorithm is validated with an extensive simulation with high real time traffic using NS3. The results show significant improvement of CMMR in terms of packet delivery, and end-to-end delay.