Packet Overhearing Research Articles

Exploiting Wireless Broadcast Advantage for Energy Efficient Packet Overhearing in WiFi

The energy efficiency of WiFi interfaces has become a significant concern for battery-powered mobile stations. In WiFi networks, a station's backoff procedure is interrupted by other stations’ channel activities to receive and decode useless packets that are not intended for it, which consumes a non-negligible amount of its energy. To reduce the energy consumption induced by such packet overhearing, we propose a novel transmission scheme, data symbol silence (DSS), which inserts silent data symbols into the front part of a data packet at the physical layer to encode information. By exploiting the wireless broadcast advantage, the embedded information is received by neighboring stations. Data symbol level energy detection is used to extract the embedded information without receiving and decoding the whole data packet. Thus, unintended receivers can quickly stop useless packet receiving and processing. The signal-to-noise ratio (SNR) gap in current WiFi networks is utilized to ensure the inserted silent data symbols do not affect the correct decoding of the original data packet. We analyze the minimum SNR required for effective DSS and implement DSS to validate its feasibility. Compared with the 802.11 standards, our studies show that DSS significantly improves the energy efficiency of WiFi interfaces.

COPS: Cooperative Statistical Misbehavior Mitigation in Network-Coding-Aided Wireless Networks

The altruistic user behavior and the isolation of malicious users are fundamental requirements for the proper operation of any cooperative network. However, the widespread use of new communication techniques that improve the cooperative performance (e.g., network coding) hinders the application of traditional schemes on malicious users detection, which are mainly based on packet overhearing. In this paper, we introduce a cooperative nonparametric statistical framework, namely COPS, for the mitigation of user misbehavior in network coding scenarios. Given that the behavior of adversaries cannot be characterized by certain probability distributions, the proposed scheme exploits two well-known nonparametric statistical methods, i.e., Kruskal–Wallis analysis and Conover–Iman multiple comparisons, for the detection and identification, respectively, of malicious users in the network. It is worth noting that the COPS framework does not require monitoring of the wireless channel and additional overhead, as its operation is based on the processing of the existing control packets. We assess the performance of the proposed scheme in various scenarios, showing that COPS is able to effectively handle attacks in the network, even when malicious users adopt a smart probabilistic misbehavior.

A Traffic Reduction Method for Crowdsourced Multi-View Video Uploading

The integration of video streams captured by many mobile cameras (contributors) at a crowded event into a multi-view video enables remote viewers to experience the different perspectives of the event. However, because of the resource-constrained nature of wireless networks and the redundant transmission due to the highly correlated streams from multiple mobile cameras at the same event, traffic reduction is necessary to ensure the efficiency of the uploading of crowdsourced video streams. In this paper, we propose a content-based video uploading scheme for crowdsourced multi-view video streaming with the goal of reducing the video traffic from crowdsourced contributors. To achieve this, the proposed scheme uses differential encoding with multiple reference streams by means of packet overhearing. To realize differential encoding across the network of contributors for higher traffic reduction, our scheme combines three techniques: correlation estimation, reference selection, and transmission order determination. First, we utilize the correlation among the contributors based on the content features of the captured video streams using the information-bound reference. Second, in the design of the reference selection that determines the dependencies among the contributors we use two threshold values, determining the number of references for differential encoding at each contributor. Finally, we schedule the transmission order of the contributors to increase the number of differential encoding opportunities within their network. Our evaluation results show that the proposed scheme achieves a traffic reduction of up to 31% with a quality improvement of up to 2.7 dB in the connected network of contributors.

It Can Drain Out Your Energy: An Energy-Saving Mechanism Against Packet Overhearing in High Traffic Wireless LANs

Energy efficiency is a critical issue of wireless devices. As the packets are broadcast to the devices in the wireless transmission media, all active neighboring devices have to spend their energy receiving the packets though the packets are not addressed to them, which is called as the packet overhearing problem . The real-world traffic trace analysis reveals that the energy cost on the packet overhearing accounts for the majority of the devices’ energy inefficiency in high traffic wireless local area networks (WLANs). In this paper, we propose a novel sample-address sample-duration (SASD) scheme to solve the energy inefficiency of the packet overhearing problem. By adding a new SASD header, which contains the critical information, in front of the data packet at the physical layer, the SASD enables the devices to discern the required information in the energy-saving downclocking mode. Consequently, the non-destination devices of the packet can switch to the sleeping mode to avoid the packet overhearing problem. We demonstrate the feasibility of the SASD through hardware experiments and evaluate its energy-saving performance through ns-2 simulations. The results show that the SASD can greatly outperform the existing approaches in the high traffic WLAN scenario.

μNap: Practical micro-sleeps for 802.11 WLANs

In this paper, we revisit the idea of putting interfaces to sleep during packet overhearing (i.e., when there are ongoing transmissions addressed to other stations) from a practical standpoint. To this aim, we perform a robust experimental characterisation of the timing and consumption behaviour of a commercial 802.11 card. We design μNap, a local standard-compliant energy-saving mechanism that leverages micro-sleep opportunities inherent to the CSMA operation of 802.11 WLANs. This mechanism is backwards compatible and incrementally deployable, and takes into account the timing limitations of existing hardware, as well as practical CSMA-related issues (e.g., capture effect). According to the performance assessment carried out through trace-based simulation, the use of our scheme would result in a 57% reduction in the time spent in overhearing, thus leading to an energy saving of 15.8% of the activity time.

A Countermeasure to Eavesdropping on Data Packets by Utilizing Control Packet Overhearing for Radio overlapping Reduced Multipath Routing in Ad Hoc Networks

Ad hoc networks are autonomously distributed wireless networks which consist of wireless terminals (hereinafter, referred to as nodes). They do not rely on wireless network infrastructures such as base stations. Relaying nodes and their surrounding nodes are susceptible to data theft and eavesdropping because nodes communicate via radio waves. Previously, we had proposed the secure dispersed data transfer method for encryption, decryption, and transfer of the original data packets. To use the secure dispersed data transfer method securely, we had proposed using the node-disjoint multipath routing method. In this method, multiple versions of encrypted data packets are transferred along each disjoint multipath to counter data packet theft. We had also proposed the enhanced version of the aforementioned routing method to reduce radio area overlap by using rebroadcasting of control packets to counter eavesdropping attacks. In this paper, we propose a multipath routing method to reduce radio area overlap through the introduction of control packet overhearing. We introduce control packet overhearing mechanisms to eliminate excess control packet counts and latency in the pathfinding process. Our main contributions are as follows: (1) our proposed method can reduce radio area overlap without  each node's geographical location information (e.g., using GPS information); (2) our proposed method also can eliminate excess control packets and latency without degradation of the security. Furthermore we conducted simulation experiments to evaluate our proposed method. We observed that our proposed method can construct the desired paths with a smaller amount of control packets and a shorter latency in the pathfinding process. We also conducted additional experiments to discuss the applicable scope of our proposed method. As a result, we confirmed that our proposed method was more effective as the average number of adjacent nodes increased.

Wlan Performance Improvement by Header Compression and Packet Overhearing Reduction

Abstract For wireless systems, it is of vital importance to use the scarce radio resources in an efficient way. The main targets are to reduce the power consumption and increase the throughput of wireless devices. Using header compression both throughput can be increased and power can be saved. Using packet overhearing reduction power can be saved. This paper presents the achieved performance improvements when using these two methods. The simulation results are confirmed by analytical calculations. We show that we can achieve up to 35% power save when combining both methods and close to 0.1 additional normalized throughput.

Performance evaluation of network coding in IEEE 802.11 wireless ad hoc networks

We evaluate the practical network coding (NC) gain in a wireless ad hoc networks. First, we introduce how network coding can be applied to IEEE 802.11 ad hoc networks. Next, we find obstructive factors by which the NC gain may decrease as compared with the theoretical NC gain. Finally, through the performance evaluation, we analyze why a performance difference occurs between practical and theoretical NC gains owing to the suggested obstructive factors. According to the simulated results, even though there is some overhead caused by the characteristics of the media access control (MAC) protocol and control signals to apply NC to wireless ad hoc networks, the practical NC gain is almost the same as the theoretical gain in an ideal environment for NC. However, in the NC system with the hidden node problem, the NC gain decreases because of packet collision. In the NC system using a promiscuous mode where packet overhearing is possible, nodes consume more power than the conventional system because of overhearing packets. For instance, when the number of overhearing nodes not related to NC is set to 15, the power reduction rate is −38.04%. Furthermore, under the network conditions inappropriate for NC, such as asymmetric flows and scarce coding structures, the NC gain can be considerably reduced. For example, in 5×5 and 7×7 grid topology networks, the load reduction rate by NC are only 4.12% and 7.01%, respectively. Therefore, research to solve the suggested obstructive factors is necessary to achieve sufficient NC gain in a practical wireless network such as an IEEE 802.11 ad hoc networks.

Coverage and connectivity guaranteed topology control algorithm for cluster‐based wireless sensor networks

AbstractOne of the most challenging issues in wireless sensor networks is to meet the requirements of coverage and connectivity under given energy constraints. Most existing coverage and connectivity algorithms work to form tree networks when sensor nodes do not have location information of themselves. However, a tree topology network does not perform well in terms of energy efficiency and scalability if compared with a cluster network. In this paper, a novel topology control algorithm called Adaptive Random Clustering (ARC) is proposed to form a cluster network with required coverage and connectivity without location information. The performance of its coverage intensity and connectivity is analyzed based on the characteristics of cluster topology, and their proper parameters are determined. ARC inherits an excellent energy efficiency from cluster topology and avoids the collisions and overhearing of data packets. A good scalability can be achieved as only a limited number of channels are needed in ARC for a large‐scale network. Furthermore, ARC can adjust the number of active nodes adaptively according to the required coverage to balance the energy consumption. Simulation results demonstrate that required coverage and connectivity can be satisfied and network lifetime is prolonged significantly. Copyright © 2010 John Wiley & Sons, Ltd.

Energy Efficient Routing Protocols for Mobile Ad Hoc Networks

Nodes in a mobile ad hoc network have limited battery power. If a node is used frequently for transmission or overhearing of data packets, more energy is consumed by that node and after certain amount of time the energy level may not be sufficient for data transmission resulting in link failure. In this paper, we have considered two routing protocols-Dynamic Source Routing (DSR) & Minimum Maximum Battery cost Routing (MMBCR) and studied their performances in terms of network lifetime for the same network scenario. Simulations are carried out using NS2. Finally from the simulation results we have concluded that MMBCR gives more network lifetime by selecting route with maximum battery capacity thereby outperforming DSR. General Terms Energy efficiency, MANETS, Routing Protocols.

Cross-layer design for efficient resource utilization in wimedia UWB-based WPANs

Ultra-WideBand (UWB) communications has emerged as a promising technology for high data rate Wireless Personal Area Networks (WPANs). In this article, we address two key issues that impact the performance of a multihop UWB-based WPAN: throughput and transmission range. Arbitrary selection of routes in such a network may result in reserving an unnecessarily long channel time, and hence low network throughput and high blocking rate for prospective reservations. To remedy this situation, we propose a novel cross-layer resource allocation design. At the core of this design is a routing technique (called RTERU) that uses the allocated channel time as a routing metric. RTERU exploits the dependence of this metric on the multiple-rate capability of an UWB system. We show that selecting the route that consumes the minimum channel time while satisfying a target packet delivery probability over the selected route is an NP-hard problem. Accordingly, RTERU resorts to approximate path selection algorithms (implemented proactively and reactively) to find near-optimal solutions at reasonable computational/communication overhead. We further enhance the performance of RTERU by integrating into its design a packet overhearing capability. Simulations are used to demonstrate the performance of our proposed solutions.

On Supporting High-Quality 3D Geometry Multicasting over IEEE 802.11 Wireless Networks

With significant improvements in both wireless technologies and computational capabilities of mobile devices, it is now possible to exchange and render 3D graphics over wireless networks on mobile devices such as PDAs and laptops. In this paper, we consider a typical scenario where users holding mobile devices of different display resolutions and rendering capabilities request the same 3D object in an IEEE 802.11 wireless LAN. Several schemes are proposed. First, to support high-quality 3D content multicasting, we analyze the characteristics of 3D data and choose the minimum data set for unicast in order to avoid excessive bandwidth consumption. Then, a transcoding algorithm is proposed to address the issue of multiuser diversity. In addition, to take advantage of the nature of broadcast in wireless medium and further mitigate the issue of serious resource usage due to large data size, we propose to broadcast certain less important refinement data. With the proposed hybrid unicast/broadcast transmission scheme and a packet overhearing mechanism, good scalability can be achieved. Finally, we schedule the unicast according to users' experienced link condition to handle user mobility. Simulation results show that the proposed schemes in combination can efficiently achieve the dual objectives of low transmission delay and small distortion.

Design of a low power and low latency MAC protocol with node grouping and transmission pipelining in wireless sensor networks

In wireless sensor networks (WSNs), the strategies of periodical sleep and contention to use the channel for transmission are efficient in terms of power consumption and channel utilization. However, contention and sleep cause other power consumption problems, namely the overhearing of the control packets and increased transmission latency. In this paper, we propose the use of node grouping and transmission pipelining to reduce power consumption and transmission delay. In the design of node grouping, there are several groups in a WSN, where nodes in different groups wake up at different time. Each sensor node is initially set to belong to one of these groups. In contrast to the situation in which all nodes hear the control packets during the contention period, node grouping reduce the number of nodes that overhears the control packets at the same time to reduce power consumption, To establish communication between nodes belonging to different groups, we assign a group table to each node. The group table recodes the group indices of all the neighbors of that node. With looking up a group table in a sensor node, a sender can wake up at the group time of the receiver. As a result, two nodes belonging to different groups can communicate with other. With regard to transmission delay of a multi-hop path in WSNs, if a sender transmits data to the receiver and the receiver cannot send the data to the next receiver right now, the transmission delay increases. To reduce the transmission delay, we propose the transmission pipelining method. Transmission pipelining makes the group number of the nodes on a path to be continuous. Therefore, the sensor node is thus able to transmit data to the sink node pipelining. From the simulation results, when the number of groups is 2, the power consumed in transmitting a byte (mJ/byte) and the transmission delay in our proposed design are better than those of SMAC by about 50%. When the number of groups is 4, although the transmission delay is only a little better than that of SMAC, the power consumed in transmitting a byte in our proposed design is much less than the power consumed in SMAC by 75%.

Support of Efficient Route Discovery in Mobile Ad Hoc Access Networks

SUMMARY The Public Wireless Local Area Network (PWLAN) is an emerging service for wireless access to the Internet. However, the service coverage of the PWLAN is limited by the deployment of access points (APs) because only those who stay near the AP can access the PWLAN. A feasible way of extending the service coverage of a PWLAN is to deploy mobile ad hoc access networks (MAHANs) so that users who are not in an AP’s radio coverage area can send their packets to the AP in a multihop manner. However, in a MAHAN, mobile nodes that intend to access the Internet have to discover routes to the AP first, which may result in considerable bandwidth cost. In this paper, we propose the Appointed BrOadcast (ABO) method to reduce the cost of route discovery in MAHANs. Using the ABO method can achieve this goal on the basis of packet overhearing. Functions that are necessary for network and data link layers to employ the ABO method are also discussed. Simulation results show that using the ABO method can significantly reduce the cost on route discoveries. Due to the widespread use of legacy IEEE 802.11 nodes, the problem of how ABO-enhanced and legacy IEEE 802.11 nodes can coexist in a MAHAN is also discussed.