|
Network Management & Wireless Sensor Networks |
|
|
|
|
Written by martcon
|
|
Wednesday, 10 March 2010 15:48 |
|
All networks from Storage Area Networks (SANs) to Telecommunications infrastructure have to be managed. Network Management is the process of configuring and monitoring the behaviour of a network and can be divided into the the following fields: Configuration Management, Fault Management, Traffic Management, Performance Management and Load Management. Configuration Management entails the configuring of settings for network equipment while the closely related Load Management involves the transfer of operating systems and configuration setting files to the networked equipment. The goal of Traffic Management is to prevent bottlenecks of data within the system while, as its name implies, Fault Management is the detection and reporting of errors generated by the networked equipment. Finally, Performance Management often leverages Business Intelligence software to provide reports regarding key metrics for the network. Of course, there are other areas in Network Management such as Service Management that we won't discuss here.
Typically, the goal of network management is to provide comprehensive information in a timely fashion. However, this goal is incompatible with one of the key goals of Wireless Sensor Networks (WSNs) which is to minimise communication to prevent a drain on battery power. Furthermore, the number of sensor motes is exponentially larger than the number of items of equipment in a typical network. This means that different mechanisms for managing WSNs need to be examined.
One mechanism proposed (See http://www.springerlink.com/content/2284243411648051/fulltext.pdf?page=1) is the Sectoral Sweeper scheme where a central node is placed in a region of the WSN to allocate tasks to nodes in that region. As messages and tasks are delivered through a central node rather than through multihop transmission, energy consumption is reduced. SNMS (Sensor Network Management System - see http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.69.3012&rep=rep1&type=pdf) provides a lightweight system for querying the health of the WSN and logging events. The services provided by SNMS take up a minimum of RAM and can be integrated into TinyOS-based motes. RRP (see http://www.springerlink.com/content/r1964x44r101432w/) is based on supply chain management methodology and divides the WSN up into different functional areas and facilitates cooperation between these different regions to enhance energy usage and performance. The 'lifecycle' of the data acquisition is managed from its capture in the 'manufacturing' area to its processing and delivery in a 'warehouse' and 'service' area. The 'manufacture' area consists of sensor motes that generate or filter the raw data while the 'transportation' area relays data to a base station. Motes at the 'warehouse' and 'service' areas manage data by eliminating redundant data thus reducing energy consumption.
The selection of mechanisms outlined all focus on energy saving which is a key goal of any network management paradigm for a WSN. There are also mechanisms for managing traffic such as Siphon. SenOS and AppSleep can be used for power management of the nodes while Sympathy can be used for fault monitoring. |
|
|
Written by martcon
|
|
Thursday, 04 March 2010 10:33 |
|
Given the volume of data produced by Wireless Sensor Networks, Smart Meters and the other smart objects that make up the 'Internet of Things', there is a clear requirement for this data to be transformed into meaningful information using Vertoda Middleware and Business Intelligence tools such as Crystal Reports and Business Objects. There are also other tools available which can be incorporated into the Vertoda Framework. R (http://www.r-project.org/) is a free software environment for statistical computing and graphics and can be used for data mining applications. The Apache Hadoop project (http://hadoop.apache.org/) is free open source software which provides data processing, aggregation, storage and warehousing functionality. Both these tools can be used in conjunction with Vertoda to provide a rich reporting environment for decision making. And, of course, as previously discussed, Data Grids and Complex Event Processing (CEP) can also play key roles in analysing data for Green IT and other networks of smart objects. |
|
SCADA Systems & Wireless Sensor Networks Part 2: Security Concerns |
|
|
|
|
Written by martcon
|
|
Wednesday, 24 February 2010 14:29 |
|
SCADA systems gather data from remote sensors and transfer that data to a central controller for analysis. As this data is frequently of a confidential nature, securing that data is an important challenge. We can take two perspectives when examining Wireless Sensor Network (WSN) security - the security of the data in transit and the security of the network itself.
The data transferred from a WSN has to be protected from unauthorised viewing, unauthorised tampering or both. Cryptographic systems prevents viewing and tampering while Digital Signatures ensure data integrity. Digital signatures can ensure that data is from authorised senders and can also ensure that data arrives untampered. Quality of Service (QoS) metrics can also be met using digital signatures by ensuring that data isn't duplicated maliciously or otherwise. Encryption provides further protection by guarding against eavesdropping i.e. ensuring that the data cannot be viewed while it's in transit.
From the point of view of Network Security, device identities must be provable and data transfer from one mote to another or from a mote to a SCADA system must be authorised. Attacks should be logged and key management should be feasible. This latter point is critical given the constrained nature of a typical sensor mote in terms of processing power and memory. For this reason non-traditional cryptographic techniques such as Elliptic Curve Cryptography (ECC) and Identity Based Encryption (IBE) should be considered. The former is an option that has been used by TinyOS and Java-based sensor motes.
SCADA-based WSNs typically consist of many motes with, as noted above, severe resource constraints. Given that SCADA systems have physical access to devices, the use of cryptographic protections might not be enough as attacks on these systems could be catastrophic in nature. It is argued (See http://www.mdpi.com/1424-8220/9/11/9380/pdf) that a reputation system is required. Within this system only trusted data is transferred from sensor to server while the server provides the reputation to the sensor .
Given the critical nature of SCADA systems for many industries and utilities, the data that flows through the system needs to be secure. The introduction of WSNs into a SCADA system can damage that security unless appropriate security provisions are made be they digital signing, cryptography or a reputation-based system. |
|
|
SCADA Systems & Wireless Sensor Networks Part 1 - Overview & Issues |
|
|
|
|
Written by martcon
|
|
Friday, 19 February 2010 15:19 |
|
The key value of Wireless Sensor Networks is the monitoring of physical and industrial environments. This data needs to be transformed into meaningful information that can be used by business decision makers using the Vertoda Framework. Furthermore, much of this data can also play a role in SCADA (Supervisory Control And Data Acquisition) systems. SCADA systems are fundamental to operations in the pharmaceutical, oil & gas, food processing and other process driven industries and the data provided by WSNs could certainly enrich the information provided by such systems.
One option for connecting WSNs to SCADA systems is to use Vertoda Middleware. The Vertoda Framework will capture the data from the WSNs and distribute pre-sorted and translated information to the SCADA system. This would be an ideal mechanism for fusing the data capturing power of WSNs with the well established SCADA systems used in certain industries. To date, WSNs have not met market expectations for certain sectors. The answer to that issue may be to make their data more easily available to the existing systems used by an industry sector.
The other option for connecting WSNs to SCADA is to connect the SCADA system directly to the WSNs. However, this is more difficult than initally appears as custom software will need to be created for the system. This could be achieved using a bespoke Vertoda Data Capture module.
Within a SCADA model, data is captured by sensors and communicated to a central controller which analyses the data and takes appropriate actions. It is a well established standard and has the flexibility to accomodate wireless networks. However, as noted, up to now WSNs have not been deployed extensively within industries that typically use SCADA systems. It can be argued that the key reason for this is that industries such as pharmaceuticals are regulatory driven and WSNs were too much of risk for plant and process management. The key requirement for the use of WSNs is that they be reliable. WSNs in industries such as oil & gas and pharmaceuticals need to withstand harsh, often outdoor environments. Up to recently, WSNs were still technology that was primarily suited to benign indoor environments but the motes have become much more robust.
WSNs must also easily interoperate with other devices and systems. The data produced by WSNs does not exist in isolation - it is required by other devices and systems to make decisions and take actions. Vertoda solves this problem by making WSN information available to any other system within the organisation. WSNs must facilitate route configuration i.e. if one mote is damaged it must not be a bottleneck or point of failure for the rest of the network. The other area of concern for the process industry is the perceived insecurity of WSNs - a topic we will return to in a future blog. |
|
Wireless Sensor Networks & Wind Farms |
|
|
|
|
Written by martcon
|
|
Wednesday, 10 February 2010 14:12 |
|
The use of wind power to generate energy is growing very quickly. However, as we have noted previously, there are a number of challenges facing wind farms. Wind Turbines are complex devices that require frequent maintenance. One possible aid for wind farms may be wireless sensor networks (WSNs) which can be used for predictive and monitoring purposes.
The key value of wireless sensor networks (WSNs) is their ability to collect data in real-time from physical environments that are often hard to monitor. This data can then be correlated to ascertain trends and product information for analysis and decision making. One way in which WSNs could assist wind farms is in the problem of wind power prediction. The power generated by wind turbines is contingent upon wind speed. Sensor motes can be easily integrated with a wind speed meter (sometimes referred to as an anemometer) to provide real-time data on the wind speed in a wind farm location. This data can then be transformed into information and correlated with historical data on the power generated by a particular wind turbine given that wind speed. Such cumulative information for all the turbines in a wind farm can then be used to predict the power generated by that farm for a particular period. Since the power generated by a farm is ultimately sold to an electricity utility, this information can be used to predict revenue for the organisation for a particular period. Such a solution would be low cost and, given the nature of WSNs, easy to deploy.
In addition to its role in predicting power and revenue generation, wind speed can also be used for operational purposes, for example, to determine the correct blade rotation for the turbine. WSNs can also be used to measure vibrations within the turbine equipment to determine the prospect of failure and prevent unnecessary downtime. Given the requirement for 2 weeks scheduled maintenance mandated by many turbine vendors this is a key issue. WSNs can be used for condition monitoring generally. Condition monitoring offers significant value to a wind farm operator as the cost of downtime is significant not only in terms of equipment repair but also in terms of lost revenue. This issue is further exaceberated by the fact that wind farms are often in locations such as mountains and hills that are hard to access. Indeed, offshore wind farms are becoming more prevalent. The diagnosis by sensor motes of impending failures can result in a number of actions. Sensors embedded within a turbine could interact with the equipment to take a number of actions such as the scheduling of maintenance, the reconfiguration of certain operations or the emergency shutdown of the equipment.
In addition to measuring wind speed, WSNs can be used to measure other characteristics of the physical environment including temperature, humidity, rainfall and light. WSNs can also be used to provide identifications for individual turbines and farms and their data can be fused with Web 2.0 presentation technologies to provide real-time identification of a wind farm, its turbines and the conditions of same. Using 3G, broadband, wireless or satellite communications, data can be transferred from the remote locations in which wind farms typically reside.
The Vertoda Framework can capture data from WSNs and transform this data into meaningful and timely information. Using this information, wind farms can reduce maintenance costs, improve operational efficiencies and more accurately measure their revenues.
|
|
|
|
|
<< Start < Prev 1 2 3 4 5 6 7 8 9 10 Next > End >>
|
|
Page 4 of 19 |
|