In this position paper, we investigate the use of wireless sensor network (WSN) technology for gr... more In this position paper, we investigate the use of wireless sensor network (WSN) technology for ground surveillance. The goal of our project is to develop a prototype of WSN for outdoor deployment. We aim to design a system, which can detect and classify multiple targets (e.g., vehicles and troop movements), using inexpensive off-the-shelf wireless sensor devices, capable of sensing acoustic and magnetic signals generated by different target objects. In order to archive our goals, we intend to design a system, which is capable of automatic selforganization and calibration. Such a system would need to be capable of performing detection and tracking of targets as well as sending the real time enemy mobility information to a command centre. Real-time tacking with WSN is extremely challenging since it requires high system robustness, real time decision making, high frequency sampling, multi-modality of sensing, complex signal processing and data fusion, distributed coordination and wide area coverage. We propose a Hybrid Sensor Network architecture (HSN), tailored specifically to meet these challenges. We investigate data fusion technologies such as particle filters, to handle both environmental and sensing noises of inexpensive sensors.
Proceedings of the 26th Annual International Conference on Mobile Computing and Networking, 2020
We propose Nephalai, a Compressive Sensing-based Cloud Radio Access Network (C-RAN), to reduce th... more We propose Nephalai, a Compressive Sensing-based Cloud Radio Access Network (C-RAN), to reduce the uplink bit rate of the physical layer (PHY) between the gateways and the cloud server for multi-channel LPWANs. Recent research shows that single-channel LPWANs suffer from scalability issues. While multiple channels improve these issues, data transmission is expensive. Furthermore, recent research has shown that jointly decoding raw physical layers that are offloaded by LPWAN gateways in the cloud can improve the signal-to-noise ratio (SNR) of week radio signals. However, when it comes to multiple channels, this approach requires high bandwidth of network infrastructure to transport a large amount of PHY samples from gateways to the cloud server, which results in network congestion and high cost due to Internet data usage. In order to reduce the operation's bandwidth, we propose a novel LPWAN packet acquisition mechanism based on Compressive Sensing with a custom design dictionary that exploits the structure of LPWAN packets, reduces the bit rate of samples on each gateway, and demodulates PHY in the cloud with (joint) sparse approximation. Moreover, we propose an adaptive compression method that takes the Spreading Factor (SF) and SNR into account. Our empirical evaluation shows that up to 93.7% PHY samples can be reduced by Nephalai when = 9 and SNR is high without degradation in the packet reception rate (PRR). With four gateways, 1.7x PRR can be achieved with 87.5% PHY samples compressed, which can extend the battery lifetime of embedded IoT devices to 1.7.
The ability of connecting machines to machines and machines to infrastructure has gradually evolv... more The ability of connecting machines to machines and machines to infrastructure has gradually evolved over the past few years and recently was given a prominent name known as pervasive networking. All the devices involved in this ecosystem sense gather enormous amount of data and process them into constructive actions. Furthermore, connecting all the smart devices brings people, data, and objects together. CISCO has predicted that there will be 50 billion connected devices by The work has been carried out by Dr. Chitra Javali and Dr. Girish Revadigar as a part of Postdoctoral Research at UNSW Sydney, Australia.
Proceedings of the 10th EAI International Conference on Body Area Networks, 2015
Security in Wireless Body Area Networks (WBAN) is of major concern as the miniature personal heal... more Security in Wireless Body Area Networks (WBAN) is of major concern as the miniature personal health-care devices need to protect the sensitive health information transmitted in wireless medium. It is essential for these devices to generate the shared secret key used for data encryption periodically. Recent studies have exploited wireless channel characteristics, e.g., received signal strength indicator (RSSI) to derive the shared secret key during random body movement of subject wearing devices. However, in the absence of node mobility, these schemes have very low bit rate capacity, and fail to derive keys with good entropy, which is a big threat for security. In this work, we study the effectiveness of combining dual antennas and frequency diversity for obtaining uncorrelated channel samples to improve entropy of key and bit rate in static channel conditions. We propose a novel mobility independent RSSI based secret key generation protocol-iARC for WBAN. We conduct an extensive set of experiments in real time environments on sensor platforms used in WBAN to validate the performance of iARC. iARC has 800 bps secrecy capacity and generates 128 bit key in only 160 ms.
Biochemical and Biophysical Research Communications, 1997
A novel homologue of p38 MAP kinase, called SAPK4, has been cloned which shares 61% amino acid id... more A novel homologue of p38 MAP kinase, called SAPK4, has been cloned which shares 61% amino acid identity with p38 and is expressed predominantly in testes, pancreas and small intestine. We also cloned an alternative form of p38beta, termed p38beta2, which lacks the additional 8 amino acid insertion unique to p38beta. p38, p38beta, p38beta2, ERK6/p38gamma/SAPK3, and SAPK4 were characterized with respect to stimulus-dependent activation in transfected cells, substrate specificity, and sensitivity to inhibition by pyridinyl imidazoles. All homologues were stimulated, although to differing extents, by IL-1beta, TNF, sorbitol, and UV. Only SAPK3 and SAPK4 were stimulated significantly by PMA. p38beta showed the weakest activation overall. MBP, ATF-2, and both MAPKAP kinase-2 and kinase-3 were good substrates of p38 and p38beta in vitro. In contrast, only MBP, ATF2, and MAPKAP kinase-3 proved to be significant substrates of SAPK3 and SAPK4, and of these three, MAPKAP kinase-3 was by far the weakest. p38beta had very poor kinase activity for all substrates except MBP. While both p38 and p38beta2 were comparably inhibited by SB 203580 and SB 202190, neither SAPK3 nor SAPK4 were inhibited. p38beta was partially inhibited by both inhibitors. These data suggest that SAPK3 and SAPK4 form a distinct subset of the p38 MAP kinases with different expression pattern, response to stimuli, substrate specificity, and inhibitor sensitivity.
We consider the problem of data collection from a continental-scale network of energy harvesting ... more We consider the problem of data collection from a continental-scale network of energy harvesting sensors, applied to tracking mobile assets in rural environments. Our application constraints favour a highly asymmetric solution, with heavily duty-cycled sensor nodes communicating with powered base stations. We study a novel scheduling optimisation problem for energy harvesting mobile sensor network, that maximises the amount of collected data under the constraints of radio link quality and energy harvesting efficiency, while ensuring a fair data reception. We show that the problem is NP-complete and propose a heuristic algorithm to approximate the optimal scheduling solution in polynomial time. Moreover, our algorithm is flexible in handling progressive energy harvesting events, such as with solar panels, or opportunistic and bursty events, such as with Wireless Power Transfer. We use empirical link quality data, solar energy, and WPT efficiency to evaluate the proposed algorithm in extensive simulations and compare its performance to state-of-the-art. We show that our algorithm achieves high data reception rates, under different fairness and node lifetime constraints.
Proceedings. 2006 31st IEEE Conference on Local Computer Networks, 2006
This paper investigates the problem of how to improve TCP performance in multi-rate Ad-hoc networ... more This paper investigates the problem of how to improve TCP performance in multi-rate Ad-hoc networks with congested links. To improve network performance, different rate adaptation algorithms, such as Automatic Rate Fallback (ARF) and Receiver-Based AutoRate (RBAR), have been proposed to adapt the data rate according to the current channel quality. Opportunistic Auto Rate (OAR) protocol is an optimisation for any existing rate adaptation algorithm which leads to a significant performance gain by providing temporal fairness. We analyze the reasons for the high performance gain obtained using OAR, and show that the OAR protocol does not work well for TCP communications in Ad-hoc networks where nodes use different data rates to communicate with each other (heterogeneous). Based on these analysis, we propose a Congestion Reactive Opportunistic Auto Rate (CROAR) protocol, which is a new rate adaption enhancement tailored to improve TCP performance in heterogeneous multi-hop Ad-hoc networks. Extensive simulations show that CROAR, compared to OAR and RBAR, produces significant throughput and end-to-end transmission latency improvements while only marginally relaxing temporal fairness.
38th Annual IEEE Conference on Local Computer Networks, 2013
The IEEE 802.11 MAC protocol performance degrades severely as the number of stations in the colli... more The IEEE 802.11 MAC protocol performance degrades severely as the number of stations in the collision domain increases in a saturated network. Employing cooperative retransmission at the MAC layer provides a way to work around the performance limitations by exploiting the broadcast nature of wireless communication. This paper presents a new routing metric, termed Expected Cooperative Forwarding Delay (ECFD), with the aim of selecting a minimum end-to-end delay path for multi-hop multirate wireless mesh networks. Different from previously proposed cooperative-aware routing metrics such as ORETT, the ECFD metric is based not only on expected cooperative transmission time but accounts for queueing and backoff delays in the path selection process. We describe the design and implementation of ECFD, and conduct extensive simulation experiments in random topologies showing that, under various realistic network traffic patterns, the use of ECFD instead of ORETT and ETT significantly improves both end-to-end delay and throughput.
IEEE Wireless Communications and Networking Conference, 2005
The performance of Direct Sequence Code Division Multiple Access (DS-CDMA) sensor networks is lim... more The performance of Direct Sequence Code Division Multiple Access (DS-CDMA) sensor networks is limited by Multiple Access Interference (MAI). This paper proposes using frequency division to reduce the MAI in a DS-CDMA sensor network. We provide theoretical characterization of the mean MAI at a given node and show that a small number of frequency channels can reduce the MAI significantly. In addition, we provide a comparison of our proposed system to systems which do not use frequency division or which employ contention based protocols. Our study found that, by using only a small number of frequency channels, our system has less channel contention, lower packet latency, higher packet delivery ratio and lower energy consumption. We consider a wireless sensor network that consists of numerous sensor/actuator devices with integrated sensing, embedded microprocessors, low-power communication radios, on-board energy, with location awareness and organized in an ad hoc multi-hop network. Since sensor network applications are expected to utilize low data rate (e.g., 1-100Kbps), have small data packet size (e.g., 50 bytes), and sensors normally have limited energy, buffer space, and other resources, the contention based protocols may not be a suitable choice. Contention based protocols suffer from both low network throughput and long packet delays. Associating with each small data packet transmission, the RTS/CTS control packet exchange produces significant overheads. Woo and Culler [14] state that an RTS-CTS-DATA-ACK handshake sequence in transmitting a packet can constitute up to 40% overhead with small packet size in sensor networks. Although IEEE 802.11 standard specifies that RTS/CTS can be avoided with small data packet transmission, this may not be a suitable choice for sensor networks. Given the low data rate (e.g., 20Kbps) in sensor networks, a small data packet will take longer time to transmit than in an IEEE 802.11 network which has higher data rate (e.g., 2Mbps). As a result, the collision probability in sensor networks is much higher. Blough et al. [5] proved the crude lower bound that no contentions occur in a wireless channel with following lemma: Lemma 1 Lett be the time necessary to transmit a packet. For d = mt, the probability that no contention will occur in a wireless channel is strictly grater than exp(− 3h(h−1) 2m), where h denotes the number of nodes that are contending for the channel. An example was also given with 33 contending nodes, where d must be around 16000t to achieve a probabilistic guarantee of no contention of at least 0.9. Assume thatt represents the transmission time of a packet with 802.11 data rate (2Mbps) in above example. Now considering the same packet is transmitted with sensor network data rate (20Kbps). During the same period of time d, the probability of no collision will occur is 5.023 × 10 −5 , which is almost zero. In other word, collisions will always occur. The consequence is that control packet (RTS/CTS) exchange is inevitable to avoid collisions. Moreover, some energy efficient algorithms proposed for contention based protocols for sensor network require the information embedded in RTS/CTS packets. For example, SMAC [19] uses the transmission time embedded in RTS/CTS to turn off unintended receivers to avoid the energy consumption caused by overhearing. Furthermore, contention based protocols also suffer from the well documented hidden node and exposed node problems.
Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems, 2012
This paper proposes an opportunistic rate-adaptive expected transmission time (ORETT) metric, whi... more This paper proposes an opportunistic rate-adaptive expected transmission time (ORETT) metric, which exploits cooperative (relay-aided) retransmissions to achieve high-throughput routing in multi-rate wireless mesh networks. This metric captures the combined effects of MAC-layer cooperative retransmission by neighbor nodes with transmission rate diversity (and rate-dependent link quality). In our approach, a relay node is selected among one-hop neighbors to assist with packet retransmissions and minimize the expected retransmission time. The paper describes the design and implementation of the ORETT routing metric using the DSR routing protocol. Our extensive simulation on the Qualnet platform confirms that multi-rate routing using ORETT significantly reduces the overall transmission time while yielding higher packet delivery ratio compared to single rate unicast or noncooperative ETT based routing.
In this position paper, we investigate the use of wireless sensor network (WSN) technology for gr... more In this position paper, we investigate the use of wireless sensor network (WSN) technology for ground surveillance. The goal of our project is to develop a prototype of WSN for outdoor deployment. We aim to design a system, which can detect and classify multiple targets (e.g., vehicles and troop movements), using inexpensive off-the-shelf wireless sensor devices, capable of sensing acoustic and magnetic signals generated by different target objects. In order to archive our goals, we intend to design a system, which is capable of automatic selforganization and calibration. Such a system would need to be capable of performing detection and tracking of targets as well as sending the real time enemy mobility information to a command centre. Real-time tacking with WSN is extremely challenging since it requires high system robustness, real time decision making, high frequency sampling, multi-modality of sensing, complex signal processing and data fusion, distributed coordination and wide area coverage. We propose a Hybrid Sensor Network architecture (HSN), tailored specifically to meet these challenges. We investigate data fusion technologies such as particle filters, to handle both environmental and sensing noises of inexpensive sensors.
Proceedings of the 26th Annual International Conference on Mobile Computing and Networking, 2020
We propose Nephalai, a Compressive Sensing-based Cloud Radio Access Network (C-RAN), to reduce th... more We propose Nephalai, a Compressive Sensing-based Cloud Radio Access Network (C-RAN), to reduce the uplink bit rate of the physical layer (PHY) between the gateways and the cloud server for multi-channel LPWANs. Recent research shows that single-channel LPWANs suffer from scalability issues. While multiple channels improve these issues, data transmission is expensive. Furthermore, recent research has shown that jointly decoding raw physical layers that are offloaded by LPWAN gateways in the cloud can improve the signal-to-noise ratio (SNR) of week radio signals. However, when it comes to multiple channels, this approach requires high bandwidth of network infrastructure to transport a large amount of PHY samples from gateways to the cloud server, which results in network congestion and high cost due to Internet data usage. In order to reduce the operation's bandwidth, we propose a novel LPWAN packet acquisition mechanism based on Compressive Sensing with a custom design dictionary that exploits the structure of LPWAN packets, reduces the bit rate of samples on each gateway, and demodulates PHY in the cloud with (joint) sparse approximation. Moreover, we propose an adaptive compression method that takes the Spreading Factor (SF) and SNR into account. Our empirical evaluation shows that up to 93.7% PHY samples can be reduced by Nephalai when = 9 and SNR is high without degradation in the packet reception rate (PRR). With four gateways, 1.7x PRR can be achieved with 87.5% PHY samples compressed, which can extend the battery lifetime of embedded IoT devices to 1.7.
The ability of connecting machines to machines and machines to infrastructure has gradually evolv... more The ability of connecting machines to machines and machines to infrastructure has gradually evolved over the past few years and recently was given a prominent name known as pervasive networking. All the devices involved in this ecosystem sense gather enormous amount of data and process them into constructive actions. Furthermore, connecting all the smart devices brings people, data, and objects together. CISCO has predicted that there will be 50 billion connected devices by The work has been carried out by Dr. Chitra Javali and Dr. Girish Revadigar as a part of Postdoctoral Research at UNSW Sydney, Australia.
Proceedings of the 10th EAI International Conference on Body Area Networks, 2015
Security in Wireless Body Area Networks (WBAN) is of major concern as the miniature personal heal... more Security in Wireless Body Area Networks (WBAN) is of major concern as the miniature personal health-care devices need to protect the sensitive health information transmitted in wireless medium. It is essential for these devices to generate the shared secret key used for data encryption periodically. Recent studies have exploited wireless channel characteristics, e.g., received signal strength indicator (RSSI) to derive the shared secret key during random body movement of subject wearing devices. However, in the absence of node mobility, these schemes have very low bit rate capacity, and fail to derive keys with good entropy, which is a big threat for security. In this work, we study the effectiveness of combining dual antennas and frequency diversity for obtaining uncorrelated channel samples to improve entropy of key and bit rate in static channel conditions. We propose a novel mobility independent RSSI based secret key generation protocol-iARC for WBAN. We conduct an extensive set of experiments in real time environments on sensor platforms used in WBAN to validate the performance of iARC. iARC has 800 bps secrecy capacity and generates 128 bit key in only 160 ms.
Biochemical and Biophysical Research Communications, 1997
A novel homologue of p38 MAP kinase, called SAPK4, has been cloned which shares 61% amino acid id... more A novel homologue of p38 MAP kinase, called SAPK4, has been cloned which shares 61% amino acid identity with p38 and is expressed predominantly in testes, pancreas and small intestine. We also cloned an alternative form of p38beta, termed p38beta2, which lacks the additional 8 amino acid insertion unique to p38beta. p38, p38beta, p38beta2, ERK6/p38gamma/SAPK3, and SAPK4 were characterized with respect to stimulus-dependent activation in transfected cells, substrate specificity, and sensitivity to inhibition by pyridinyl imidazoles. All homologues were stimulated, although to differing extents, by IL-1beta, TNF, sorbitol, and UV. Only SAPK3 and SAPK4 were stimulated significantly by PMA. p38beta showed the weakest activation overall. MBP, ATF-2, and both MAPKAP kinase-2 and kinase-3 were good substrates of p38 and p38beta in vitro. In contrast, only MBP, ATF2, and MAPKAP kinase-3 proved to be significant substrates of SAPK3 and SAPK4, and of these three, MAPKAP kinase-3 was by far the weakest. p38beta had very poor kinase activity for all substrates except MBP. While both p38 and p38beta2 were comparably inhibited by SB 203580 and SB 202190, neither SAPK3 nor SAPK4 were inhibited. p38beta was partially inhibited by both inhibitors. These data suggest that SAPK3 and SAPK4 form a distinct subset of the p38 MAP kinases with different expression pattern, response to stimuli, substrate specificity, and inhibitor sensitivity.
We consider the problem of data collection from a continental-scale network of energy harvesting ... more We consider the problem of data collection from a continental-scale network of energy harvesting sensors, applied to tracking mobile assets in rural environments. Our application constraints favour a highly asymmetric solution, with heavily duty-cycled sensor nodes communicating with powered base stations. We study a novel scheduling optimisation problem for energy harvesting mobile sensor network, that maximises the amount of collected data under the constraints of radio link quality and energy harvesting efficiency, while ensuring a fair data reception. We show that the problem is NP-complete and propose a heuristic algorithm to approximate the optimal scheduling solution in polynomial time. Moreover, our algorithm is flexible in handling progressive energy harvesting events, such as with solar panels, or opportunistic and bursty events, such as with Wireless Power Transfer. We use empirical link quality data, solar energy, and WPT efficiency to evaluate the proposed algorithm in extensive simulations and compare its performance to state-of-the-art. We show that our algorithm achieves high data reception rates, under different fairness and node lifetime constraints.
Proceedings. 2006 31st IEEE Conference on Local Computer Networks, 2006
This paper investigates the problem of how to improve TCP performance in multi-rate Ad-hoc networ... more This paper investigates the problem of how to improve TCP performance in multi-rate Ad-hoc networks with congested links. To improve network performance, different rate adaptation algorithms, such as Automatic Rate Fallback (ARF) and Receiver-Based AutoRate (RBAR), have been proposed to adapt the data rate according to the current channel quality. Opportunistic Auto Rate (OAR) protocol is an optimisation for any existing rate adaptation algorithm which leads to a significant performance gain by providing temporal fairness. We analyze the reasons for the high performance gain obtained using OAR, and show that the OAR protocol does not work well for TCP communications in Ad-hoc networks where nodes use different data rates to communicate with each other (heterogeneous). Based on these analysis, we propose a Congestion Reactive Opportunistic Auto Rate (CROAR) protocol, which is a new rate adaption enhancement tailored to improve TCP performance in heterogeneous multi-hop Ad-hoc networks. Extensive simulations show that CROAR, compared to OAR and RBAR, produces significant throughput and end-to-end transmission latency improvements while only marginally relaxing temporal fairness.
38th Annual IEEE Conference on Local Computer Networks, 2013
The IEEE 802.11 MAC protocol performance degrades severely as the number of stations in the colli... more The IEEE 802.11 MAC protocol performance degrades severely as the number of stations in the collision domain increases in a saturated network. Employing cooperative retransmission at the MAC layer provides a way to work around the performance limitations by exploiting the broadcast nature of wireless communication. This paper presents a new routing metric, termed Expected Cooperative Forwarding Delay (ECFD), with the aim of selecting a minimum end-to-end delay path for multi-hop multirate wireless mesh networks. Different from previously proposed cooperative-aware routing metrics such as ORETT, the ECFD metric is based not only on expected cooperative transmission time but accounts for queueing and backoff delays in the path selection process. We describe the design and implementation of ECFD, and conduct extensive simulation experiments in random topologies showing that, under various realistic network traffic patterns, the use of ECFD instead of ORETT and ETT significantly improves both end-to-end delay and throughput.
IEEE Wireless Communications and Networking Conference, 2005
The performance of Direct Sequence Code Division Multiple Access (DS-CDMA) sensor networks is lim... more The performance of Direct Sequence Code Division Multiple Access (DS-CDMA) sensor networks is limited by Multiple Access Interference (MAI). This paper proposes using frequency division to reduce the MAI in a DS-CDMA sensor network. We provide theoretical characterization of the mean MAI at a given node and show that a small number of frequency channels can reduce the MAI significantly. In addition, we provide a comparison of our proposed system to systems which do not use frequency division or which employ contention based protocols. Our study found that, by using only a small number of frequency channels, our system has less channel contention, lower packet latency, higher packet delivery ratio and lower energy consumption. We consider a wireless sensor network that consists of numerous sensor/actuator devices with integrated sensing, embedded microprocessors, low-power communication radios, on-board energy, with location awareness and organized in an ad hoc multi-hop network. Since sensor network applications are expected to utilize low data rate (e.g., 1-100Kbps), have small data packet size (e.g., 50 bytes), and sensors normally have limited energy, buffer space, and other resources, the contention based protocols may not be a suitable choice. Contention based protocols suffer from both low network throughput and long packet delays. Associating with each small data packet transmission, the RTS/CTS control packet exchange produces significant overheads. Woo and Culler [14] state that an RTS-CTS-DATA-ACK handshake sequence in transmitting a packet can constitute up to 40% overhead with small packet size in sensor networks. Although IEEE 802.11 standard specifies that RTS/CTS can be avoided with small data packet transmission, this may not be a suitable choice for sensor networks. Given the low data rate (e.g., 20Kbps) in sensor networks, a small data packet will take longer time to transmit than in an IEEE 802.11 network which has higher data rate (e.g., 2Mbps). As a result, the collision probability in sensor networks is much higher. Blough et al. [5] proved the crude lower bound that no contentions occur in a wireless channel with following lemma: Lemma 1 Lett be the time necessary to transmit a packet. For d = mt, the probability that no contention will occur in a wireless channel is strictly grater than exp(− 3h(h−1) 2m), where h denotes the number of nodes that are contending for the channel. An example was also given with 33 contending nodes, where d must be around 16000t to achieve a probabilistic guarantee of no contention of at least 0.9. Assume thatt represents the transmission time of a packet with 802.11 data rate (2Mbps) in above example. Now considering the same packet is transmitted with sensor network data rate (20Kbps). During the same period of time d, the probability of no collision will occur is 5.023 × 10 −5 , which is almost zero. In other word, collisions will always occur. The consequence is that control packet (RTS/CTS) exchange is inevitable to avoid collisions. Moreover, some energy efficient algorithms proposed for contention based protocols for sensor network require the information embedded in RTS/CTS packets. For example, SMAC [19] uses the transmission time embedded in RTS/CTS to turn off unintended receivers to avoid the energy consumption caused by overhearing. Furthermore, contention based protocols also suffer from the well documented hidden node and exposed node problems.
Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems, 2012
This paper proposes an opportunistic rate-adaptive expected transmission time (ORETT) metric, whi... more This paper proposes an opportunistic rate-adaptive expected transmission time (ORETT) metric, which exploits cooperative (relay-aided) retransmissions to achieve high-throughput routing in multi-rate wireless mesh networks. This metric captures the combined effects of MAC-layer cooperative retransmission by neighbor nodes with transmission rate diversity (and rate-dependent link quality). In our approach, a relay node is selected among one-hop neighbors to assist with packet retransmissions and minimize the expected retransmission time. The paper describes the design and implementation of the ORETT routing metric using the DSR routing protocol. Our extensive simulation on the Qualnet platform confirms that multi-rate routing using ORETT significantly reduces the overall transmission time while yielding higher packet delivery ratio compared to single rate unicast or noncooperative ETT based routing.
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