Literature Review of the Industrial Wireless

Literature Review of the Industrial WirelessIndustrial tunercommunication groundwork goes beyond a hand full of WSN in the field sending back information to a localised force frame, the broader picture of a truly industrial radiocommunication infrastructure envisages a system where the entire crude and muck up set is integ calculated wirelessly and all(a) arms of the organisation stomach wirelessly assenting selective information from approved wireless thingumajigs from any location in the world. This provides a wireless platform for more efficient management, operation and maintenance of the crude and turgidity facility.This review focuses on WSN in the oil color and go down on application, WSN resides in level zero of the ISA 95.01 hierarchy model. The oil and be adrift industry have utilised WSN for a add together of years, up until the release of industry specific wireless technologies i.e. Wireless HART and ISA 100.11a, all of the oil and bollix WSN install base were based on vendor proprietary technology, as a head there s incessantlyal operability issues with early(a) vendors device and host systems 13. Oil and gas facility operators and maintenance teams undercoat themselves requiring multiple vendor devices and systems to meet the process application needs, resulting in high maintenance and operational be defeating the purpose for having WSNs.The vast majority of the first generation WSN were based on basic office wireless technologies, as a result the first generation WSN where plagued with a emergence of issues that is to say manoeuvre reliability, function usage, device processing capabilities, coverage atomic number 18a, suitability for use in hazardous beas, credential and data latency issues. All these issues were a cause of major concern in the oil and gas industry towards the deployment of WSN. 14 talk in the oil and gas industry demands the selected technology provides high availability, reliability, so-and-s o coexistence with other net incomes on the plant, accommodate to an international standard, stern operate in hazardous argona, can maneuver data in strong while, is easily interoperable and is secure to outside intrusion and is cost effective 25. All these requirements plus the ever changing RF environment and high levels electromagnetic noise from heavy duty machinery on an oil and gas facility has made it difficult over the years for WSN to prove successful and be considered the norm when considering communication technologies.The release of process industry specific WSN technologies like WirelessHART and ISA 100.11a, has significantly increased the interest in WSN in the oil and gas industry, it is estimated that investment in wireless infrastructure in the oil and gas industry will more than double from 1.2 million devices to over 3 million device between 2009 to 2015 30. With the advances in WSN technology, the potential of WSN to ram home a suppressd CAPEX and OPEX cost savings, and possible health and safety and environmental benefits 25, is proving too attractive to be overlooked by oil and gas industry looking to reduce cost and improve plant safety.WSN are primarily based on the IEEE 802.15 family of technologies, which are designated as WPAN, WPAN typically consist of low data rates and a scam coverage area 17. WSN utilise a regularise of frequencies in the school of thought band of frequencies i.e. 900 MHz, 2.4 GHz and 5.8 GHz, these frequencies propagate through office cubicles, drywall, wood and other materials found in homes and offices but tend to bounce of large object like steel and concrete. overdue to the high density of steel structures in an oil and gas facility, the first generation of WSN where plague by signal echo or multi path fading , high levels of signal echo and multipath fading transcend to infections been cancelled 14.Some of the wireless technologies used in Industrial applications include Bluetooth, ZigBee, W irelessHART, ISA 100.11a etc. IEEE 802.15.1 AKA Bluetooth is a short range radio technology which operates in 2.4 GHz ISM frequency band it was first introduced by the telecom vendor Ericsson in 1994 as a wireless alternative for RS232 communication 18. Bluetooth is relatively low- tycoon, low-rate wireless affiance technology, intended for point-to-point communications 19. Bluetooth operates with three contrastive screenes of devices videlicet Class 1 devices which have a range of about 100meters, class 2 devices which have a range of about 10 meters, and class 3 devices with a range of 1m 20.Bluetooth operates based on the features of Adaptive Frequency Hopping (AFH) and Forward Error subject field (FEC), AFH detects the potential for channel interference and sorrylists channels found to have interference, to handle temporary interference the dodge re-tries the blacklisted channels and if the interference is no longer present channel can be used 31. For bail and authentica tion purposes an acknowledgement is sent by the receiver to the circulateter in the lead a connection can be made between devices, Bluetooth too uses FHSS which adds an inherent level of security, the hop sequence switches channels 1,600 time per second qualification capturing a single hop extremely difficult. Data transmitted using Bluetooth is en computed before transmission increasing the security of the transmission also password protection ensures only devices with identical passwords can participate on the meshwork. Bluetooth also utilises a controlled device pairing process to determine which products can communicate, making devices invincible so they can non be discover by other devices 22.Bluetooth is limited to eight devices per ne twork and also has a limitation on the packet sizes 21. This limitation in the number of device per network makes the Bluetooth technology an impractical solution for WSN in the Oil and gas industry. Typically the quantity of nodes in an o il and gas application would be in the hundreds which would mean have several Bluetooth networks on the facility.ZigBee is based on the IEEE 802.15.4 and earlier developed for home automation. It is a low-cost, low-power, short range, wireless, mesh network technology which operates in the 2.4 GHz ISM band and uses DSSS modulation. All nodes in a ZigBee network share the same channel and frequency hopping is not permitted, at start-up of a ZigBee network scans are carried to establish a channel with little or no interference, this channel is then used for its data transmission 23. A ZigBee network is capable of supporting hundreds of devices, the network architecture can be star, tree or mesh topologies. The technology uses three different types of devices namely ZigBee end devices, ZigBee router and a ZigBee coordinator.ZigBee supports both non beacon and beacon enabled networks, non-beacon networks are allowed to transmit any time that the radio channel is open and idle. This cre ates a free-for-all environment in which collisions occur regularly when two or more devices try to transmit at the same time. In this mode, the co-ordinator and routers must be active at all time, and so it is best suited to mains powered devices 24. A beacon enabled network can transmit only in its designated time slot this regulates transmissions making collisions less likely. All nodes in the network are expected to synchronize their on-board clocks to this frame. Each node is allocated a specific time-slot within this super-frame during which it, and only it, is allowed to transmit and receive its data 24.ZigBee utilizes the security mechanisms defined by IEEE 802.15.4, it using counter with cipher block chaining communicate authentication code (CCM) and AES-128 encryption, giving the option to use encryption-only or integrity-only 23. The technology permits the use of three keys namely Network key, Link key and Master key. To join the network the master key is unavoidable, for end-to-end data encryption the link key is required and provides the highest level of security, the network key is shared between all devices on the network and provides a lower level of security 23.ZigBee networks offer no variety in frequency since the whole network shares a single static channel, this makes the network highly susceptible to signal jamming. Frequency selective fading due to the high density of concrete and steel structures present in an oil and gas facility is also a major concern as this can bring out all ZigBee communication. The use of a single static channel increases the chance of interference from other systems and increases discipline as the network size grows. In non-beacon enabled networks collisions forces retransmissions and this increase latency time making the technology incommensurable for critical monitor or control applications 23.ZigBee has existed for any(prenominal) time now and has been updated a number of times to improve features lik e reliability, latency and security which are of utter or so importance but ZigBee has still not been able to cope with the stringent requirements needed for authentic and secure data transmission on an oil and gas facility.Wireless HART is one of only two released open wireless technology specific for process measurement and control applications 25. It is modelled on the OSI model with its physical layer bases on the IEEE 802.15.4 for low rate WPAN, it operates in the 2.4 GHz ISM frequency band. The application layer is based on the oil and gas industry wide accepted HART protocol. The technology was released in 2007, and was developed on a fall of fundamental requirements namely it must be easy to use and deploy, it should be a self- organising and self- healing network and it should be scalable, reliable and secure 23. Wireless HART employs TDMA where all devices on the network are time synchronised and communicate in a prescheduled 10ms fixed time slot, this reduces data colli sion on the network and also reduces the power consumption of network devices 23.The Wireless HART network is made up of different devices which include field devices, network gate behaviors which include network and security theatre directors. Field devices are organized in either mesh or star topology with the gateway acting as a keep going between the field device network and the host system 20. Mechanisms like DSSS, FHSS, CSMA/CA, channel hopping, channel black listing are pick out by the technology to improve coexistence with other wireless networks in the environs.WirelessHART adopts two routing mechanisms to ensure data reliability and availability these routing mechanisms are called graph and source routing. During graph routing the network omnibus establishes the different routes which form the graph, each device on the network stores these routes and uses the predefined routes to identify the next device to frontward data to during data transmission. During source rou ting a definitive list of the devices from the source device through to the cultivation which the data is to be routed is included the data packet header 20. Graph routing gives the WirelessHART the ability to self-heal if mold routes on the graph is un lendable an alternate route can be taken. WirelessHART adopts a mandatory security requirement, both the sending device and receiving device uses counter with cipher block chaining meat authentication code (CCM) together with AES-128 as the underlining encryption methods. Session keys, joint keys and network keys are generated by the security manager and network manager to prevent intrusion and attacks against the network 23.WirelessHART since its release has proven to be a reliable technology, it is well researched in both the academic and industrial fields with reputable instrumentation suppliers investing hard the production and continued research and development of devices operating on the technology. The features and capabil ities of the technology are addressed in more detail in section 4.1 of this report.ISA100.11a is the second of the two open wireless technologys specific for process measurement and control applications, ISA 100.11a is a Low data rate wireless mesh network technology operating in the 2.4 GHz ISM frequency band, it is modelled on the OSI model and adopts IEEE 802. 15.4 as its Physical layer. The technology was released in 2009 and is suitable for process applications where delays of up to 100ms can be tolerated 27. ISA 100.11a technology contracts to deliver Low energy consumption devices, easy scalable networks, interoperability with legacy infrastructure and applications, a secure and racy wireless network which is capable of coexisting with other wireless devices in the industrial work aloofness 29.An ISA-100.11a network is made up of non-routing and routing field devices, a system manager, a security manager, backbone routers and gateways. Non-routing devices are the field dete ctors / actuators, while routing devices could also act as field sensor/actuator or a router. Routing devices are important in the mesh network, data is transmitted from the source to the destination through a number of hops, with the routers responsible for routing the data to the right destination. They can also use alternative paths to improve reliability sympathetic to WirelessHART network.Data packets are routed from one subnet over the backbone network to its destination, the backbone router is responsible for this routing function, the routing destination can be another subnet or the gateway. Thegatewayis the physical interface between the field network and the plant host network. The system manager is responsible for the administrative functions and communication configuration of the network 29.ISA 100.11a supports frequency hopping and channel blacklisting, this eliminates bad frequency bands and improves big-bonedness against interference. The technology also uses DSSS modulation technique which divides the signal into small fragments and spreads it over the available frequency channels, this disguises the signal making it appear as noise to the other wireless technologies with in the range as a result overcoming interference and increasing communication reliability 28. ISA.100.11a is a very robust technology, in addition to DSSS, the technology utilises three different diversity techniques, namely space diversity, frequency diversity and time diversity 28.ISA100.11a utilises integrity checks and optional encryption to guarantee the security of the network, the technology also utilises AES-128 bits, message authentication and encryption codes. In addition to this a shared global key, a private stellate key or certificate are required in order a for a sensor node to be permitted to join an ISA100.11a network 28.The technology provides a synchronizing sampling mechanism, this mechanism provides drop-off of reporting rates and transmissions can be configured to take place when the rate of change of the calculated data exceeds a certain defined threshold. Adaptive transmission power control is also adopted by ISA 100.11a devices, this provides field devices the ability to dynamically select a transmit power level, thereby optimizing the power used by the device. Finally the routing capability of field devices can be turned on or off depending on the location of a device here by reducing the power demands of the device to suit the design requirements 28.The application layer of ISA 100.11a is flexible and has tunnelling capabilities, this permits the user to maintain compatibility with oil and gas facility legacy protocols like Fieldbus Foundation, HART, Profibus, Modbus, and others 29. ISA.100.11a adopts 6LoWPAN protocol for its network and transport layers, this offers interoperability with internet based hosts and sensor nodes in other WSN networks with IPv6 compatibility 20.ISA 100.11a has proven to be a reliable WSN in th e oil and gas industry, monitoring and alerting, asset management, prognostic maintenance, condition monitoring are the application areas which have specific requirements and performance characteristics that can be covered by ISA.100.11a technology.ZigBee and Bluetooth are some of the technologies which have not really been accepted by the oil and gas industry as a means of wireless communication for process monitoring due to some shortfalls such as, ZigBee cannot provide the required QoS support for handling latency and message flow determinism required by industrial applications, ZigBee only utilizes DSSS hence its performance can easily degrade in case of continual noise in the environs. Bluetooth on the other hand, isnt sufficiently scalable to handle the vast number of measuring points on an oil and gas facility.However, WirelessHART and ISA100.11a technologies have been adopted for industrial applications due to their ability to settled data transmission, reliability, secur ity, reduced data latency and low-cost features. WirelessHART does not support multiple protocols as ISA100.11a does, the transmission of HART messages are the only information specified and supported by WirelessHART while ISA 100.11a support most of the oil and gas legacy communication protocols like Foundation fieldbus, MODBUS, Profibus, HART etc. 28.The extreme environments go through on an oil and gas facility i.e. high temperatures, high level of EMI, large steel and concrete structures and constant movement of heavy machinery makes wireless communication highly unreliable in this environment. The release of industry specific technologies i.e. Wireless HART and ISA 100.11a has somewhat addressed the concerns over reliability, security, signal latency of a WSN, respect to the standards by wireless device vendors has also lead to operability across multiple vendor devices.Confidence has openhanded in the use of WSN since the release of industry specific technologies with a han d full of vendors and end users championing the way on WSN. The install base of WSN is continually increasing and this will aid the industry gain a better understand the technology. Till date majority of the install base are on stringently monitoring only points due to latency concerns with WSN, further academic and industry based research is required in the use of WSN for fast acting closed loop control and safety critical applications with the aim resolving the latency issues associated with WSN.