Wireless Communications

Topology control in a sensor network balances load on sensor nodes and increases network scalability and lifetime. Clustering sensor nodes is an effective topology control approach. We propose a novel distributed clustering approach for long-lived ad hoc sensor networks. Our proposed approach does not make any assumptions about the presence of infrastructure or about node capabilities, other than the availability of multiple power levels in sensor nodes. We present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of the node residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. HEED terminates in O(1) iterations, incurs low message overhead, and achieves fairly uniform cluster head distribution across the network. We prove that, with appropriate bounds on node density and intracluster and intercluster transmission ranges, HEED can asymptotically almost surely guarantee connectivity of clustered networks. Simulation results demonstrate that our proposed approach is effective in prolonging the network lifetime and supporting scalable data aggregation.

/pdf/heed-a-hybrid-energy-efficient-distributed-clustering-4c3cjgsfv9.pdf

HEED: a hybrid, energy-efficient, distributed clustering approach for ad hoc sensor networks

http://www.csun.edu/~andrzej/COMP529-S05/papers/Mesh%20Networks%20Survey.pdf

Wireless mesh networks: a survey

http://cpham.perso.univ-pau.fr/ENSEIGNEMENT/PAU-UPPA/RESA-M2/Clustering-abasi.pdf

A survey on clustering algorithms for wireless sensor networks

In today's competitive industry marketplace, the companies face growing demands to improve process efficiencies, comply with environmental regulations, and meet corporate financial objectives. Given the increasing age of many industrial systems and the dynamic industrial manufacturing market, intelligent and low-cost industrial automation systems are required to improve the productivity and efficiency of such systems. The collaborative nature of industrial wireless sensor networks (IWSNs) brings several advantages over traditional wired industrial monitoring and control systems, including self-organization, rapid deployment, flexibility, and inherent intelligent-processing capability. In this regard, IWSN plays a vital role in creating a highly reliable and self-healing industrial system that rapidly responds to real-time events with appropriate actions. In this paper, first, technical challenges and design principles are introduced in terms of hardware development, system architectures and protocols, and software development. Specifically, radio technologies, energy-harvesting techniques, and cross-layer design for IWSNs have been discussed. In addition, IWSN standards are presented for the system owners, who plan to utilize new IWSN technologies for industrial automation applications. In this paper, our aim is to provide a contemporary look at the current state of the art in IWSNs and discuss the still-open research issues in this field and, hence, to make the decision-making process more effective and direct.

/pdf/industrial-wireless-sensor-networks-challenges-design-1p149rqzw2.pdf

Industrial Wireless Sensor Networks: Challenges, Design Principles, and Technical Approaches

Recently, in an effort to improve the performance of wireless networks, there has been increased interest in protocols that rely on interactions between different layers. However, such cross-layer design can run at cross purposes with sound and longer-term architectural principles, and lead to various negative consequences. This motivates us to step back and reexamine holistically the issue of cross-layer design and its architectural ramifications. We contend that a good architectural design leads to proliferation and longevity, and illustrate this with some historical examples. Even though the wireless medium is fundamentally different from the wired one, and can offer undreamt of modalities of cooperation, we show that the conventional layered architecture is a reasonable way to operate wireless networks, and is in fact optimal up to an order. However the temptation and perhaps even the need to optimize by incorporating cross-layer adaptation cannot be ignored, so we examine the issues involved. We show that unintended cross-layer interactions can have undesirable consequences on overall system performance. We illustrate them by certain cross-layer schemes loosely based on recent proposals. We attempt to distill a few general principles for cross-layer design. Moreover, unbridled cross-layer design can lead to spaghetti design, which can stifle further innovation and be difficult to upkeep. At a critical time when wireless networks may be on the cusp of massive proliferation, the architectural considerations may be paramount. We argue that it behooves us to exercise caution while engaging in cross-layer design.

A cautionary perspective on cross-layer design

In this paper, we consider the problem of power control when nodes are nonhomogeneously dispersed in space. In such situations, one seeks to employ per packet power control depending on the source and destination of the packet. This gives rise to a joint problem which involves not only power control but also clustering. We provide three solutions for joint clustering and power control. The first protocol, CLUSTERPOW, aims to increase the network capacity by increasing spatial reuse. We provide a simple and modular architecture to implement CLUSTERPOW at the network layer. The second, Tunnelled CLUSTERPOW, allows a finer optimization by using encapsulation, but we do not know of an efficient way to implement it. The last, MINPOW, whose basic idea is not new, provides an optimal routing solution with respect to the total power consumed in communication. Our contribution includes a clean implementation of MINPOW at the network layer without any physical layer support. We establish that all three protocols ensure that packets ultimately reach their intended destinations. We provide a software architectural framework for our implementation as a network layer protocol. The architecture works with any routing protocol, and can also be used to implement other power control schemes. Details of the implementation in Linux are provided.

/pdf/power-control-and-clustering-in-ad-hoc-networks-537nrc1zxs.pdf

Power control and clustering in ad hoc networks

Transmit power control is a prototypical example of a cross-layer design problem. The transmit power level affects signal quality and, thus, impacts the physical layer, determines the neighboring nodes that can hear the packet and, thus, the network layer affects interference which causes congestion and, thus, affects the transport layer. It is also key to several performance measures such as throughput, delay, and energy consumption. The challenge is to determine where in the architecture the power control problem is to be situated, to determine the appropriate power level by studying its impact on several performance issues, to provide a solution which deals properly with the multiple effects of transmit power control, and finally, to provide a software architecture for realizing the solution. We distill some basic principles on power control, which inform the subsequent design process. We then detail the design of a sequence of increasingly complex protocols, which address the multidimensional ramifications of the power control problem. Many of these protocols have been implemented, and may be the only implementations for power control in a real system. It is hoped that the approach in this paper may also be of use in other topical problems in cross-layer design.

Principles and protocols for power control in wireless ad hoc networks

The results of an extensive experimental study of the performance of the TCP protocol over wireless multi-hop ad hoc networks are presented. The investigations are performed in a real indoor environment over a network of laptops equipped with off-the-shelf IEEE 802.11b wireless cards. The cards were partially covered with copper tape to reduce their range, which enabled creation of manageable topologies. Several tools were written and assembled to make the entire process of experimentation including topology setup, traffic generation, trace collection, and archival and analysis of data repeatable, reliable and as automated as possible. The experimental observations are subjected to a thorough statistical analysis. The final result of the study is a recommendation of some TCP and IEEE 802.11 parameters that are best for TCP performance over wireless multi-hop networks. The most critical of these include setting a destination dependent clamp on the sender congestion window and disabling the RTC-CTS handshake. The methods and techniques used, as well as the support tools developed, and statistical analysis, may be of larger interest in wireless network experimentation.

/pdf/experimental-investigations-into-tcp-performance-over-1tnohhgis7.pdf

Experimental investigations into TCP performance over wireless multihop networks

DARPA's Disruption-Tolerant Networking (DTN) program is developing technologies that enable access to information when stable end-to-end paths do not exist and network infrastructure access cannot be assured. DTN technology makes use of persistence within network nodes, along with the opportunistic use of mobility, to overcome disruptions to connectivity. In this paper, we describe the SPINDLE Disruption-Tolerant Networking system and related technology being developed at BBN under the DTN program. Using an open-source, standards-based core with a plugin architecture and well-specified interfaces, we enable independent development and insertion of innovative DoD-relevant technology while allowing the core system to be refined and engineered within a COTS context. SPINDLE technology innovations include: (i) routing algorithms that work efficiently across a wide range of network disruption, (ii) a name-management architecture for DTNs that supports progressive resolution of intentional name attributes within the network (not at the source), including support for "queries as names" and name-scheme translation, (iii) distributed caching, indexing, and retrieval approaches for disruption-tolerant content-based (rather than locator-based) access to information, and (iv) a declarative knowledge-based approach that integrates routing, intentional naming, policy-based resource management, and content-based access to information. We present preliminary results that show that the DTN approach outperforms traditional end-to-end approaches across a wide range of network disruption.

/pdf/the-spindle-disruption-tolerant-networking-system-4jan3cbqro.pdf

Vikas Kawadia

Papers

A cautionary perspective on cross-layer design

Power control and clustering in ad hoc networks

Principles and protocols for power control in wireless ad hoc networks

Experimental investigations into TCP performance over wireless multihop networks

The SPINDLE Disruption-Tolerant Networking System