Mean power consumption of artificial power capture in wirelessnetworks

In wireless networks, portable terminals are usually powered by battery, and they communicate through the free-space spectrum. Therefore, both the transmission power and bandwidth are scarce resources. Artificial power capture is a simple and effective method to exploit the transmission bandwidth to give a higher throughput, but it may consume a larger mean transmission power because some packets are transmitted at higher power. In this paper, we analyze the mean power consumption of artificial power capture, and formulate two capture control problems which regulate the mean power consumption and the throughput. The analysis reveals that, although some packets are transmitted at higher power, artificial power capture has a smaller mean power consumption than the case without capture when the traffic is sufficiently heavy. This is because artificial power capture can significantly increase the probability of successful transmission at heavy traffic, and hence the mean power consumed for successfully transmitting a packet is smaller     

A network coding based protocol for reliable data transfer in underwater acoustic sensor

VBF-NC (Vector Based Forwarding-Network Coding) is a reliable transport protocol for UWASNs (Underwater Acoustic Sensor Networks). It transfers packets, coded by network coding, over relay node sets, which are established by VBF (Vector Based Forwarding) routing protocol. However, only the error correction function of network coding is used by VBF-NC, the most important inbeing of network coding, which cannot only improve the throughput of network but also reduce transmission overhead, is not used by VBF-NC. So, in this paper, a network coding based protocol, called Multiple Paths and Network Coding (MPNC), is proposed. In MPNC, three disjoint paths are established firstly, and then, two groups of packets A and B, coded by network coding, are transmitted over the two side paths individually, and another group of packets C (C = A ⊕ B) are transmitted over the middle path. The results of mathematical analysis and simulations show that, compared with VBF-NC, MPNC not only improve the throughput of network but also has a higher data delivery ratio and lower energy consumption without reducing the data transmission reliability.     

Solving the near–far problem in CDMA-based ad hoc networks

In this paper, we propose a distributed CDMA-based medium access protocol for mobile ad hoc networks (MANETs). Our approach accounts for multiple access interference (MAI) at the protocol level, thereby addressing the notorious near–far problem that undermines the throughput performance in MANETs. Collision avoidance information is inserted in the clear-to-send (CTS) packets and broadcasted over an out-of-band control channel. This information is used to dynamically bound the transmission power of possible interfering nodes in the vicinity of a receiver. Data packets are transmitted at a power level such that interference-limited simultaneous transmissions can take place in the vicinity of a receiving terminal without disturbing its reception. Simulation results indicate that the proposed protocol achieves a significant increase in network throughput relative to the 802.11 approach, at no additional cost in energy consumption. Finally, we show that variable processing gain may be used to increase the capacity of the proposed protocol.     

移动Ad Hoc网络中的一种功率控制MAC协议

本文提出了一种应用于移动Ad Hoc网络中的功率控制MAC（medium access contr01）协议，通过两个通信节点之间的控制包中的信息交换来决定数据包的发送功率以及其它邻节点下一次发送RTS控制包的功率。通过仿真与IEEE 802．11 MAC协议进行比较，由仿真结果可以看出，该协议能大大减少移动节点消耗的功率，提高节点的能量利用效率，并保持系统的吞吐量性能。     

Rate selection based medium access control for full-duplex asymmetric transmission

The realization of full-duplex wireless communication is predictable. And asymmetric transmission is a practical and low-cost application scenario, where full-duplex access point (FD_AP) can communicate with two users simultaneously to receive and send packets. While, in an asymmetric transmission, the transmit power of uplink sender decides the uplink and downlink rates because of the inter-client interference, which accordingly restricts the throughput. Besides, the size of packets in uplink and downlink is generally unequal. Therefore, a WIFI network with a FD_AP and half-duplex users is studied in this paper, and a medium access control (MAC) protocol based on power control and rate selection (PCRS) is proposed. PCRS MAC employs a received signal strength based rate selection strategy to select different rates and power for uplink and downlink transmission. Then, FD_AP can establish efficient and reliable full-duplex asymmetric transmission. Simulation results show that PCRS can improve the throughput and the probability of successful asymmetric communication as compared to the distributed coordination function (DCF) and a simple full-duplex MAC protocol without PCRS. Besides, PCRS MAC also maintains a high level of fairness.

     

The Scheduling to Achieve Optimized Performance of Randomly Addressed Polling Protocol

A collision occurs in real network access if two or more packets are simultaneously transmitted. Hence, the contentioncollision must be resolved when applying a protocol in the wireless data network. In this paper,we adopt the concept of elimination and dynamic tree expansion in Randomly AddressedPolling (RAP) protocol to reduce the delay time and enhance the throughput. Analyses resultsindicate that the throughput performance of this algorithm is up to about 0.9 and thedelay time rapidly decays.     

EPCM – an efficient power controlled MAC protocol for mobile ad hoc network

To reduce interference and to save a significant amount of energy, a control of transmission power is employed in Mobile Ad hoc Network. Many researchers have reported numerous transmission power control schemes to achieve the objective. Some of those techniques use higher transmission power for control packets (Request To Send/Clear To Send) and lesser power for Data and ACK packets. These schemes, though save some amount of energy, achieve least aggregate throughput due to poor spatial reuse and hidden terminal interference. In this paper, an efficient Power Controlled Medium Access Control (EPCM) scheme is evinced, which uses uniform interference aware and minimum transmission power for both Control and Data packet. The performance of EPCM is evaluated and compared with three reported Medium Access Control protocols which are based on transmission power control schemes and is observed that the proposed protocol achieves better throughput and minimal energy consumption while avoiding the hidden terminal problem.     

PARO: Supporting Dynamic Power Controlled Routing in Wireless Ad Hoc Networks

This paper introduces PARO, a dynamic power controlled routing scheme that helps to minimize the transmission power needed to forward packets between wireless devices in ad hoc networks. Using PARO, one or more intermediate nodes called redirectors elects to forward packets on behalf of source–destination pairs thus reducing the aggregate transmission power consumed by wireless devices. PARO is applicable to a number of networking environments including wireless sensor networks, home networks and mobile ad hoc networks. In this paper, we present the detailed design of PARO and evaluate the protocol using simulation and experimentation. We show through simulation that PARO is capable of outperforming traditional broadcast-based routing protocols (e.g., MANET routing protocols) due to its energy conserving point-to-point on-demand design. We discuss our experiences from an implementation of the protocol in an experimental wireless testbed using off-the-shelf radio technology. We also evaluate the impact of dynamic power controlled routing on traditional network performance metrics such as end-to-end delay and throughput.     

Defending Against Smart Grayhole Attack Within MANETs: A Reputation-Based Ant Colony Optimization Approach for Secure Route Discovery in DSR Protocol

Moving randomly without any centralized authority, dynamic nodes constitute the Mobile Adhoc Networks on the basis of fully-fledged cooperation and native trustworthiness. Unfortunately, in real scenarios, the malicious nodes take advantage of this inherent trustworthiness to settle in and perform their suspicious activities. In the light of the growing concerns about security attacks in hostile environments, new challenges have emerged to thwart routing attacks including the smart grayhole attack, which adversely affects the availability and accuracy of the network by dropping data packets. This paper addresses this disturbing attack by monitoring the behavior of the participating nodes through a bio-inspired trust management model. The distributed trustworthiness assessment model is based on the beta reputation system combined with the Ant Colony Optimization (ACO) metaheuristic. The main focus of the beta reputation system is rating the nodes according to their successful tasks and their consumed energy, while the ACO metaheuristic maintains this reputation metric during the discovery process and calculates the preference value of each traversed path to select the most secure one. The proposed model improves the traditional Dynamic Source Routing (DSR) protocol by isolating the malicious nodes from participation in data packets transmission. The simulations conducted with the network simulator 2, show that despite the presence of numerous gray holes, the reputation-based ACO DSR (RACODSR) outperforms the standard DSR in terms of packet loss ratio by a decrease of 9.8%, packet delivery ratio by an increase of 0.22%, throughput by an increase of 0.4%, jitter by a decrease of 22.76%, the end to end delay by a decrease of 2.51% and the consumed energy by a decrease of 0.17%.

     

On the optimal flow allocation and information theoretically secure network coding design for multiple multicasts

With linear network coding (LNC), the data packets transmitted in a communication network are coded packets, which are linear combinations of original data packets. Since the coded packets can be useful for multiple destinations in multicast, LNC has been shown as a promising technology to improve the network throughput. On the other hand, the original data packets can be encoded with random symbols and transmitted in the network to make sure that a passive attacker cannot obtain the information of these original data packets when the passive attacker cannot obtain enough coded packets. Therefore, LNC also provides secure transmission without using the traditional encryption and decryption. In this paper, we will study an Information Theoretically Secure Multiple Multicasts (ITSMM) problem with the following objectives: (1) maximizing the secure transmission rate (STR), (2) minimizing the random symbol rate (RSR), and (3) minimizing the bandwidth cost (BC), when the data transmission is information theoretically secure. We firstly theoretically analyze the ITSMM problem, which shows that it is equivalent to a problem of network flow with constraints on each intermediate node. We then formulate the ITSMM problem by 3 linear programmings to get the maximum STR, the minimum RSR, and the minimum BC. After that, we prove the sufficient condition for the size of finite field over which the information theoretically secure linear multicast code (ITSLMC) can be designed. At last, we give extensive simulations, which show that the proposed algorithms are effective and efficient.     

LOP: A packet classification architecture with higher throughput and lower power consumption than TCAM

Packet classification is an important method implemented in modern network processors used in embedded systems such as routers. Current software-based packet classification techniques exhibit low performance, prompting researchers to move their focus to architectures encompassing both software and hardware components. Some of the newer hardware architectures exclusively utilize Ternary Content Addressable Memory (TCAM) to improve the performance of rule matching. However, this results in systems with high power consumption. In this paper, we propose LOP, a novel SRAM-based architecture where incoming packets are compared against parts of all rules simultaneously until a single matching rule is found for the compared bits in the packets. LOP significantly reduces power consumption as only a segment of the memory is compared against the incoming packet. Despite the additional time penalty to match a single packet, parallel comparison of multiple packets can improve throughput beyond that of the TCAM approaches, while consuming significantly less power. Compared with a state-of-the-art TCAM implementation (throughput of 495 Million Search per Second (Msps)) in 65 nm CMOS technology, on average, LOP saves 43% of energy consumption with a throughput of 590 Msps. In addition, an analysis of how the area scales is provided.     

The slow start power controlled MAC protocol for mobile ad hoc networks and its performance analysis

We propose and evaluate the performance of a new MAC-layer protocol for mobile ad hoc networks, called the Slow Start Power Controlled (abbreviated SSPC) protocol. SSPC improves on IEEE 802.11 by using power control for the RTS/CTS and DATA frame transmissions, so as to reduce energy consumption and increase network throughput and lifetime. In our scheme the transmission power used for the RTS frames is not constant, but follows a slow start principle. The CTS frames, which are sent at maximum transmission power, prevent the neighbouring nodes from transmitting their DATA frames at power levels higher than a computed threshold, while allowing them to transmit at power levels less than that threshold. Reduced energy consumption is achieved by adjusting the node transmission power to the minimum required value for reliable reception at the receiving node, while increase in network throughput is achieved by allowing more transmissions to take place simultaneously. The slow start principle used for calculating the appropriate DATA frames transmission power and the possibility of more simultaneous collision-free transmissions differentiate the SSPC protocol from the other MAC solutions proposed for IEEE 802.11. Simulation results indicate that the SSPC protocol achieves a significant reduction in power consumption, average packet delay and frequency of RTS frame collisions, and a significant increase in network throughput and received-to-sent packets ratio compared to IEEE 802.11 protocol.     

An in-band signaling protocol for optical packet switching networks

Advances in optical networking reveal that all optical networks offering a multigigabit rate per wavelength will soon become economical as the underlying backbone in wide-area networks, in which the optical switch plays a central role. One of the central issues is the design of efficient signaling protocols which can support diversified traffic types, in particular the bursty IP traffic. This paper introduces a novel signaling protocol called the sampling probe algorithm (or SPA) to be used in a class of optical packet switching systems based on wavelength division multiplexing (WDM). The proposed scheme takes a drastically different approach from all existing signaling protocols. The salient features are 1) the pretransmission coordination is using an in-band signaling protocol, and thus does not require separate control channel(s) for transmission coordination; 2) the protocol is based on a reservation (connection) scheme which is capable of supporting multimedia traffic; 3) a gated service is adopted in which each successful reservation allows multiple packets (train of packets) to be transmitted, which can significantly reduce the per packet overhead; 4) the scheduling algorithm is adaptive by allowing flexible assignment of bandwidth on-demand; 5) the channel status gathering is done in a distributed fashion, and uses a passive listening mechanism, which itself does not interfere with packet transmissions. The results demonstrate that the proposed in-band signaling protocol can achieve high throughput and stability under heavy traffic condition.     

Energy efficient routing protocols for mobile ad hoc networks

Although establishing correct and efficient routes is an important design issue in mobile ad hoc networks (MANETs), a more challenging goal is to provide energy efficient routes because mobile nodes' operation time is the most critical limiting factor. This article surveys and classifies the energy‐aware routing protocols proposed for MANETs. They minimize either the active communication energy required to transmit or receive packets or the inactive energy consumed when a mobile node stays idle but listens to the wireless medium for any possible communication requests from other nodes. Transmission power control approach and load distribution approach belong to the former category, and sleep/power‐down mode approach belongs to the latter category. While it is not clear whether any particular algorithm or a class of algorithms is the best for all scenarios, each protocol has definite advantages/disadvantages and is well suited for certain situations. The purpose of this paper is to facilitate the research efforts in combining the existing solutions to offer a more energy efficient routing mechanism. Copyright © 2003 John Wiley & Sons, Ltd.     

Fair MAC protocol for optical ring network of wavelength-shared access nodes

In this paper, a WDM optical ring consisting of access nodes with fixed transmitter-n fixed receivers (FT—FR ⁿ ) is considered. As access nodes share a wavelength channel there is trade-off between node throughput and fairness among them. In order to abbreviate the transmission unfairness and to increase the throughput, we propose p-persistent medium access control (MAC) protocol. Each node uses the carrier sense multiple access with collision avoidance (CSMA/CA) protocol to transmit packets, and decides whether to use a local empty slot with probability p when a transferred packet based on source-stripping is dropped and emptied. Numerical prediction for the proposed MAC protocol is introduced to compute the maximum node throughput under uniform traffic condition. For more detail results, we use network simulation with self-similar traffic and introduce various results. The proposed MAC protocol gives better node throughput than non-persistent protocol and shows an improved fairness factor than 1-persistent protocol. Through simulation, we also find the reasonable probability of p-persistent protocol for a given architecture.     

OAR: An Opportunistic Auto-Rate Media Access Protocol for Ad Hoc Networks

The IEEE 802.11 wireless media access standard supports multiple data rates at the physical layer. Moreover, various auto rate adaptation mechanisms at the medium access layer have been proposed to utilize this multi-rate capability by automatically adapting the transmission rate to best match the channel conditions. In this paper, we introduce the Opportunistic Auto Rate (OAR) protocol to better exploit durations of high-quality channels conditions. The key mechanism of the OAR protocol is to opportunistically send multiple back-to-back data packets whenever the channel quality is good. As channel coherence times typically exceed multiple packet transmission times for both mobile and non-mobile users, OAR achieves significant throughput gains as compared to state-of-the-art auto-rate adaptation mechanisms. Moreover, over longer time scales, OAR ensures that all nodes are granted channel access for the same time-shares as achieved by single-rate IEEE 802.11. We describe mechanisms to implement OAR on top of any existing auto-rate adaptation scheme in a nearly IEEE 802.11 compliant manner. We also analytically study OAR and characterize the delay jitter and the gains in throughput as a function of the channel conditions. Finally, we perform an extensive set of ns-2 simulations to study the impact of such factors as node velocity, channel conditions, and topology on the throughput of OAR.     

BER-based Power Scheduling in Wireless Sensor Networks

In wireless sensor networks, there are many information exchanges between different terminals. In order to guarantee a good level of Quality of Service (QoS), the source node should be smart enough to pick a stable and good quality communication route in order to avoid any unnecessary packet loss. Due to the error-prone links in a wireless network, it is very likely that the transmitted packets over consecutive links may get corrupted or even lost. It is known that retransmissions will increase the overhead in the network, which in turns increase the total energy consumption during data transmission. In this paper, we focus on the Bit Error Rate (BER) during packet transmission and propose a power scheduling scheme to reduce the total energy consumption in the routing. Our approach controls the transmission power of each transmitter to achieve the minimum energy consumption for successful packet transmission. Considering the limited bandwidth resource, we also plan the multihop route while considering the BER and network load at the same time. The simulation results show that our approach can reduce the total energy consumption during data transmission.     

Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.     

Energy Efficient Location Error Resilient Connectivity in Wireless Sensor Networks

Geographic routing for realistic conditions is often permeated with localization errors resulting in poor performance and high energy consumption. We propose a simple yet novel geographic routing method to accomplish routing in the presence of location and channel errors. In this algorithm, it is proposed that next hop node is selected based on the combined probability of distance, estimated location error and estimated channel access probability associated with neighbor nodes. The metrics observed for performance were the successful packet delivery rate and the energy consumed. Our algorithms performance is better compared to greedy forwarding techniques of algorithms such as Greedy routing scheme (GRS) and geographic random forwarding (GeRaF). Simulations show the throughput for our algorithm is better compared to others along with reducing the energy wasted on lost packets.