2014.TEL.7858
Applications of Radio Frequency Identification Technologies in Terminal Container Handling
J.K. van Zeeland, BSc BA
Applicatie van RFID technologie in Container Terminals’ Verhandelingen
Literature No
Dr. Ir. Y. Pang Dr. Ir. Y. Pang 13 September 2014
Summary
Due to the increasing use of containers, larger vessels and bigger terminals the vis-ibility of the system decreases. Container tracking and tracing becomes ever more important as well as difficult.
Large container terminals handle millions of containers per year. The containers are offloaded from vessels and are stored or directly relayed to hinterland modal-ities. During the storage containers are put on stacks and reshuffled before also being put on hinterland modalities. The in- and outflow of containers is controlled by equipment capable of handling a large variety of containers and subject to ex-ternal factors such as vessels willing to berth and hinterland modalities capable of transporting container further inland. Internal moves of containers are handled by specialised equipment sometimes capable of storing containers itself, other times a combination of equipment is used.
The physical system is complemented by data structures capable of handling ships manifests and yard manifests. However these systems rely heavily on man power and men capability of entering data into the system. This increases the potential for failure; therefore new technologies could be applied to mend the problems in the system. Terminals could benefit from the the Radio Frequency Identification (RFID) technologies.
RFID technologies consist of three parts: a transponder or tag, an antenna or reader, and a transceiver of computer. The tag and reader can exchange information via the electromagnetic field. Many different types of tags exist, such as passive or active tags in combination with read-only or read-write capabilities. A transceiver is needed to interpret the data found on the tag, the singulation of a tag. The transceiver is also capable of anti-colliding tags when multiple are presented to the reader, i.e. the transceiver can distinguish the two unique tags instead of a single signal.
The main problem with RFID technologies is that they are prone to hacks. They are easy to clone, emulate, or kill; anyone with bad intentions can ‘fry’ the tags data chip. Precautions are by and large difficult and impractical. Another problem that arises is the low readability of tags in a container terminal due to the vast amounts of steel which make a readout difficult.
Advantages that can be gained are divided in two levels: low-level and high-level. The low-level advantages are the quicker scanning and handling of containers as well as an increased source of data (which could for instance house information on humidity, temperature, etc.). The high-level advantages are those of the switch from offline to online optimization; meaning that the real-time information can be used as opposed to data that is minutes, hours or days old.
On the whole, the literature survey has shown that the researchers interested in RFID safety recommend caution when applying the technology on a large scale; researchers interested in the applicability of RFID in the container terminal environ-ment are positive. Those two do not exclude each other but the latter do not often mention (or take into account) the concerns of the former.
Acronyms
AS/RC Automated Stacker Reclaimer Cranes
AES Advanced Encryption Protocol
AGV Automated Guided Vehicles
DGPS Differential Global Positioning System
ECT Europe Container Terminal
EDI Electronic Data Interchange
EDIFACT Electronic Data Interchange For Administrations, Commerce and Transport
EIR Equipment Interchange Receipt
IC Integrated Circuit
IT Information Technology
NFC Near Field Communication
NFS Near Field Sensing
NP Non Polynomial
OCR Optical Character Recognition
QC Quay Cranes
RFID Radio Frequency Identification
RTGC Rubber Tyred Gantry Crane
SC Straddle Carrier
TUE Twenty Foot Equivalent
UID Unique Identification
USN Ubiquitous Sensor Network
Contents
1 Introduction 1
2 Container Handling 2
2.1 Flow Through Container Terminal . . . 2
2.2 Planning of Flow . . . 5
2.3 Some Numbers . . . 6
2.4 Visibility in Current Container Handling . . . 6
2.5 Opportunities . . . 7
3 Radio Frequency Identification 8 3.1 Near Field Sensing Communication Technologies . . . 8
3.2 Radio Frequency Identification . . . 9
3.3 Physical Workings of a RFID Tag . . . 10
3.4 Identification of RFID Tags . . . 11
3.5 Safety and Security . . . 12
4 Information Technology Architecture 14 4.1 Basic Structure . . . 14
4.2 Physical Implementation of RFID Technologies . . . 15
4.3 Other Productivity Gains and Optimization . . . 16
4.4 Implementations . . . 18
4.5 Synthesis . . . 18
5 Conclusions 19
6 Recommendations 20
Foreword
This literature assignment is a work holding up to the ‘scientific standard’—meaning it should be a unbiased and an uninterpreted work describing the research and find-ings of previous research in a particular field; in this case ‘RFID in container termi-nals’.
Although the ‘scientific standard’ has its triumphs it has also some downsides—in addition to epistemological limitations—it is prone to human error and biases. I shall refrain from down-talking this work too much since it could fill up books and will be philosophical in nature. For now I would like to advise the reader to be cautious in putting all its trust in the ‘scientific method’ and keep an open view regarding other work.
This report is part of the second year of the masters Transport Engineering and Logistics (TEL) which is a masters at the faculty of Mechanical Engineer-ing (ME). This report is the literature assignment, ME2110-10, and is good for 10 ECTS—totalling a workload of 280 hours. In writing this report I was supervised by Dr. Ir. Yusong Pang.
This literature survey makes use of sixty-seven references of which forty are academic papers or books (others are websites or data sheets). Of these references Steenken et al. (2004) is the most cited (770 times). Of these references twenty-four are published between 2000 and 2010. Fifteen academic references are published after 2010.
I personally believe that adopting RFID technology is a good idea, also because it has become a sort of unstoppable force. RFID integration is widespread but especially high investment markets such as the container terminals should beware of the possible hack attacks. More so than individuals their entire structure will be build upon this integration, therefore the consequences of a hack could be disastrous. This being said; the time and money saved could outweigh these downsides (as well as blind sight decision makers, since the money is made now and the disasters follow later —if ever).
1
Introduction
Current day container transport keeps increasing; more and more containers are shipped and ships keep increasing in size, according to Reuters (2014) and Port of Rotterdam (2013). Container transport is a large part of harbour proceedings; containers are thus playing an increasing important role in national and global eco-nomics.
As a result of increasing container shipments quays and terminal equipment have ever higher usage rates. With ever more containers flowing through this system the tracking and tracing—or monitoring—question is also increasingly more important. Visibility (on the whereabouts of containers) is becoming worse; a solutions needs thus to be found.
A second trend that is witnessed is the upswing in use of radio frequency identi-fication (RFID) in day to day life. The RFID has been used in supply chain man-agement and has led to increasing visibility. This survey deals with the integration of RFID on the question of visibility in the container terminal.
This report is by and large, divided into three sections: Container Handling (section 2), Near (and Far) Field Sensing (section 3) and Information Technology Architecture (section 4).
The first part is to limit the scope of further investigations but it is also meant to give a background into processes at container terminals as well as flows within this system. It concludes by describing current day tracking and tracing of containers within terminals—as an example the APM Terminal in the Port of Rotterdam is used. Within the boundaries set an exploration into, and a explanation about, modern sensing technologies is given in the second part. The report concludes by giving a description of, and requirements for, an information technology architecture needed to overcome all the boundaries set by the preceding report.
In short: this report will primarily focus on delivering an overview of the con-temporary technologies, their applicability, research and literature into the tracking and tracing of containers within a container terminal. It is based on the assump-tions that there is, nowadays, i. not a good way to identify an individual container and there are ii. only sub-optimal ways (effectiveness) to integrate this knowledge into the existing (IT) system. It is bounded by the fact that it has to be applica-ble to a (general) container terminal and that the solution will be based on radio frequency identification technologies. This report will, thus, try to show the contem-porary situation and how modern technologies can help these terminals progress to the ‘technological age’—the new-found solution should be an improvement over the existing.
2
Container Handling
The use of containers has increased in the last decades, the largest ships in 2003 were 8,000 twenty-foot equivalent units (TEU) in size according to Vis and Koster (2002), this number increased to 18,000 in 2014 (Maersk, 2014), and is likely to keep rising as the global demand for products and shipping increase. Due to the shear size of ships there is a need for accurate monitoring of containers on ships alone. Terminals suffer from the same monitoring issues, they relay millions of containers annually (Port of Rotterdam, 2013).
This chapter will provide the reader with an overview of container terminal op-erations as well as current tracking and tracing of containers (also referred to as monitoring) on the level of a container terminal. For this purpose an generic con-tainer terminal is considered—including transshipment modes and (intermediate) storage capabilities.
This chapter will set out with a description of this generic terminal and its ‘flows’ (depicted in Figure 11 and the ‘black’ box in Figure 2.) after which contemporary tracking and tracing is discussed; problems and benefits alike. This chapter will also serve to limit the scope of Chapter 3—it provides a clear boundary for the near (and far) field sensing techniques that will be considered and have to be employed. Its third purpose is to provide the reader with ample knowledge to understand the challenges in the container handling and tracking. The assumption being that current day tracking and tracing of containers is not sufficient and there is no effective way to implement contemporary systems, thus newer methods and systems (based on radio frequency identification technology) are required.
Figure 1: High level schematic of processes at a container terminal. Based on Vis and Koster (2002).
1
2.1 Flow Through Container Terminal
In essence all container terminals are the same since they have the function; con-tainers flow in and out the terminal area and are subjected to several moves on the terminal itself. Containers are, as opposed to bulk, easy to handle (i.e. they require a limited amount of handling machinery for a large variety of goods)(Hecht and Pawlik, 2007). They have (several) fixed sizes (e.g. 20 ft, 40 ft, and 45 ft2) and
offers protection from the outside (Steenken et al., 2004)).
A black box of a container terminal is shown right in Figure 2. It boils down to containers arrive, are handled and transshipped. In trying to give a functional description of the handling equipment and flow through the system we will subdivide this into three sections: inflow, outflow and internal flow, depicted left in Figure 2.
Figure 2: Right: black box with input and output for a container terminal, left: schematic of trichotomy of operations at a terminal (based on Steenken et al. (2004). The chosen equipment puts (physical) limitations to the system. Height of stack-ing and reclaimstack-ing machinery determines height of stacks, drive speeds determine driving times and hoisting speeds determine the recovery of containers (from stacks or vessels). On a tactical level, this forms the boundary conditions for the determi-nation of the necessary number of transport vehicles, according to Vis (2002). Inflow and Outflow
Inflow concerns all the containers transported into the terminal. This can be done via different modalities; these different modalities are listed below, based on Hoogsteden (2014) and Kemme (2013).
• Container vessel, serves to transport large amounts of containers (up to 18,000 TEU3) across oceans;
• feeder, serve smaller (overseas) ports and are able to carry smaller numbers of containers: approximately 300 TEU;
• barge, serves even smaller hinterland ports and carry on average 100 TEU; • truck, carrying 1.6 TEU on average serve the hinterland; and
• train, also serving hinterland with 75 TEU on average.
(The numbers that stem from the Hoogsteden (2014) are slightly different in Steenken et al. (2004) which state that trains carry, on average 120 containers.) However, in-flow from sea is most common and has the largest capacity Steenken et al. (2004). All modalities have in common that they transport containers, distances covered by the aforementioned modalities are relatively large with respect to handling equipment.
Handling equipment handling inflowing containers should be able to lift all stan-dard types of containers. It should be able to couple the lifting equipment (such as a spreader) to the container and safely transport it from A to B. After which it should be able to place the container on a dedicated spot, this can be an other piece of equipment or a place on the quay (or terminal).
Standard machinery for unloading vessels, barges, and feeders, is a quay-crane (QC) (sometimes referred to as gantry crane, or ship-to-shore cranes (Ngai et al., 2011)), these big cranes can lift containers from vessels and put them on the quay. Modern day quay cranes are able to move more than a single container per lift, some are able to lift four containers in a single lift according to World Maritime News (2014) and Bartoˇsek and Marek (2013). Operations on the berthing side are also called ‘quayside operations’, operations in the truck and train-side are called ‘hin-terland operations’ (Steenken et al., 2004). Quayside machinery must be compatible with all the aforementioned types of ships. Hinterland machinery must be able to serve trains and trucks.
For the (un)loading of trucks and trains forklifts or straddle carriers are common equipment. This equipment can also serve as transport for the internal flow (as opposed to quay cranes which are (fairly) static).
Internal flow
Internal flow can be divided into two types. First: to and fro stacks. Second: direct relay of containers from inflow-point to outflow-point. Stacks of containers serve as for storage (either for long periods or for short), direct relay is only possible when both in- and outflow-modality are available at the same time.
For transport to and fro stacks different machinery (groups) can be used, they have in common that they should be able to transport containers to stacks and place them on designated places. This can be done for instance by straddle carriers (SCs), or a combination of automated guided vehicles (AGVs), rubber-tyred gantry cranes (RTGCs), and stacker-reclaimers (AS/RCs), older systems use man-driven trucks
to transport containers over the terminal. The transport equipment can usually transport one container at the time.
Stacking and reclaiming problem of containers is a research field an sich, as is the routing of vehicles. The routing problem can be solved using various methods within operations research, a taxonomy is of different classifications of routing problems is first made by Bodin (1981), extensively researched in Bodin et al. (1983) and further refined by Desrocher et al. (1990). Steenken et al. (2004) puts it eloquently, stating that: “[m]any of the problems in container terminal logistics can be closely related to some general classes of transportation and network routing problems (and therefore more or less standard combinatorial optimization problems) discussed comprehen-sively in the literature [of Bodin].” Stahlbock and Voß (2008) says that “regarding terminal operations and equipment only very few novel aspects [. . . ] are specified in order to complement Steenken et al. (2004).” In other words: the work of Bodin (1981) and Bodin et al. (1983) still forms the basis of modern day terminal operations research.
What was referred to as the ‘stacking and retrieval problem’ is a problem con-cerned with the stacking order of containers. “Storage area is usually separated into different stacks (or blocks) which are differentiated into rows, bays and tiers.” (Steenken et al., 2004). During reshuffles containers are taken from a certain point and put into another bay, tier, row or a combination. Stacking and retrieval is a big part of daily operation and a lot of profit stands to be gained. However, this stacking sequencing problem is NP-hard to solve and will therefore always yield sub-optimal performances, as shown by Vis (2002). In other words the stacking (and retrieval) of containers is based on heuristics and ‘ad-hoc-stacking’.
2.2 Planning of Flow
In addition to the physical equipment there is also a large range of assisting systems. These assisting systems aid the equipment and consist of organisational equipment, optimizations, communications and positioning. (Steenken et al., 2004)
The arrival of containers is known more than a year in advance, according to Steenken et al. (2004), this means that a planning of berth allocation can be made as well as a planning for the stacking or relay of containers.
In each boat a manifest (or ‘bayplan’) the location and unique identifier of all containers is known, this ‘stowage plan’ is the core of container handling nowadays and is know before the ship docks. All this data is transferred to the terminal opera-tors by means of the Electronic Data Interchange for Administration, Commerce and Transport (EDIFACT; or short EDI)—on average three weeks before arrival—which supports close interaction between the different operators. (Steenken et al., 2004)
Henceforth the terminal operators system assigns a number and a slot on a stack to every container. The stowage plan for a terminal must therefore contain both information on the boats manifest as well as the terminals stowage plan. The opti-mization of container-slot allocation can answer certain objectives (Steenken et al., 2004), such as:
• maximization of crane productivity; • cost minimization; or
• minimization of yard reshuffles.
The container flow within the terminal sets strict constrictions to the information flow within the terminal; this is, however, not the only restriction. Other restrictions are set by the number of measurements in the system and their respective placement. Automatic data gathering on containers by—for instance—accurate stowing man-ifests yields benefits, according to Kia et al. (2000), including—but not limited to— the following:
• faster discharge and loading of containers;
• increased productivity through faster turnaround of containers;
• better monitoring of the storage of containers (leading to increases in stacking areas capacity)4;
• high level of accuracy of information; and
• high level of consistency of the information given to various parties in the chain of transport.
And, although the list seems very basal, it gives an accurate insight of the progress that can be achieved. The reader will be shortly introduced in tracking and tracing systems within existing terminals.
2.3 Some Numbers
To give an idea of the importance of planning, tracking and tracing of containers, a short look is taken at the APM terminal. According to APM Terminals (2014) and the World Maritime News (2013) the Rotterdam terminal, one of the largest in the world (World Shipping Council, 2014), handled 11.9 million TEU in 2012 (this number includes the smaller and older container terminal in the Waalhaven and Eemshaven; boats over 6,000 TEU can not reach these harbours, as Pielage et al. (2008) shows). The complete APM Terminal group, with its 76 terminals across the world, handled 36.3 million TEU in 2013, grossing $4.33 billion. This clearly shows the need for accurate tracking of containers.
2.4 Visibility in Current Container Handling
As said before, the ships manifest is known. This results in a planning for the quayside and hinterland-side equipment; which get assigned to the berthing vessel. The work order for trucks, AGVs, etc. is then determined. However when—for instance—QCs are unable to perform their unloading plan in a certain time-frame problems arise in re-scheduling (when no proper real-time information is available). This will lead to longer queues and truck/AGV waiting times, or congestion at other
4
This, obviously, cannot be correct. However the intended meaning is that the capacity is better used; capacity can only be increased with increased area or stacking height.
points on the terminal. This can be due to the weather conditions not allowing unloading or an operator under performing. The opposite can also be true (i.e. that jobs are performed faster than the planned time) leading to idle QCs, according to Cheung and Ngai (2009) and Ngai et al. (2011).
The current system of tracking and tracing is actually a system of allocation, relocation and retrieval of containers—by this is meant that containers are ‘reduced’ to a number with a yard location, the number can be retrieved upon request. There is no tracking involved; the system ‘knows’ where containers are. This yields problem when a container is lost.
As to ‘how’ containers enter the system: a container is picked up by the vehicle the truck has to first check-in at the entrance gate; during this process a gate house worker checks the related truck and container information with the Equipment Inter-change Receipt (EIR) and clear and combine container number to truck number, as pointed out by Hu et al. (2011). This is done by companies such as ECT (Hutchison Port Holdings (HPH), 2014). However this way of working significantly increases the chance on errors (Wang, 2008). The state of the art, according to Hu et al. (2011), is that terminals use optical character recognition (OCR) technology. But this become problematic when letters are wearing down.
The strength of the system is its ‘proven concept’-value; this system has been in use for a long time and has proven to be able to cope with the data requirements set by boats manifests and stowage systems.
However there are improvements possible, Nam and Ha (2001) suggests that new technologies can be categorized in three parts:
• intelligent planning systems (e.g. berth assignment, ship planning); • intelligent operating systems (e.g. gate control, yard control); or • unmanned handling systems (e.g. AGVs, QCs).
If we adopt this taxonomy the adoption of RFID would fall into the intelligent operating systems. Gate, yard systems and equipment control. The main effect of such implementation would be increased productivity and maximized space and equipment usage (as well as the increased visibility of containers movement).
Ting et al. (2012) shows that several terminals do not track all equipment; they track for example only rubber-tyre gantry cranes (RTGC) but leave out tracking of tractors, and (other) internal vehicles. The operators have therefore no insight into the traffic conditions in the yard. (Patrol cars cannot solve this problem because of shear size of terminals). The systems is far from continuous. The driver updates his status as soon as he has performed a task (picked up a container or delivered it at its destination) after which he awaits new orders from the operators.
2.5 Opportunities
Gharehgozli et al. (2014) states that: “[b]etter coordination among AGVs has mul-tiple benefits for internal transport operations. A smaller fleet size can be used, and (empty) travel times can be reduced. Further, due to inherent operational variability
in the system, QCs, vehicles or YCs may not be able to complete their service within the work schedule as planned by the terminal planners. In this regard, use of real-time resource status, which can be provided by automatic context capturing devices such as sensor networks, can help the terminal operators to re-plan the schedule.” These ‘capturing devices’ can be RFID enabled devices, this is thus the area in which adoption of RFID can yield results.
3
Radio Frequency Identification
Acceptance and application of near field sensing (NFS) and communication (NFC) is already widespread. Applications of such technologies can be found in mobile devices, retail tags, London underground tickets, and security tags and recently found their way into debit cards (Bright, 2014). That the acceptance is also widespread can be witness from the adoption of near field chips in European passports (European Union, 2006). The benefits of such tags are widely accepted—as are the disadvantages. Before we set out to find possible implementations of near field sensing technologies in the transport and logistics sector it is important to make a taxonomy of the different technologies that currently exist, their respective advantages as well as their drawbacks.
Guideline for these proximity cards, contactless integrated circuits cards and identification cards (which thus excludes the far field sensing protocols) is ISO/IEC (2008) but many other standards exist for documentation, encryption, etc. (an extensive list of standards can be found at RFID Journal (2014a)). An generic NFS or RFID system consists of a scanning antenna, a transceiver with decoder to interpret data and a transponder, the RFID tag (Hu et al., 2011), visually represented in Figure 3.
Figure 3: A typical RFID system, adapted from Hu et al. (2011).
3.1 Near Field Sensing Communication Technologies
Negatively formulated near field sensing is the absence of a direct line-of-sight and/or physical contact between the sender and receiver (Ting et al., 2012). Less accurate, but positively formulated, the near field sensing technologies can relay information between sender and receiver by being in each others vicinity (Want, 2006). At any rate, let us start by building an understanding ground up. Near field sensing is a broad term which is distinguishable from far field sensing is inasmuch that they are limited to the maximum of two times the wavelength used, according to the United States Labor Department (2014); see Figure 9. However this scientific notion of near-and far field will later abnear-andoned it will suffice for now.5 Near field communication technologies are mainly based on radio frequency identification (RFID) and for the
5
In articles on near field radio frequency identification tags a different notion—based on common sense—is used. This will be adopted since the reader will have a more intuitive understanding of the technology.
remainder of this chapter we will try to explain how this technology works and what its limitations are, we will end with a survey into the application of these technologies in the container terminals.
Figure 4: Relationsship between wavelengths and nearfar field definition; courtesey of United States Labor Department (2014).
3.2 Radio Frequency Identification
Radio frequency identification is a relatively simple method exchanging information. It has seen its first use in the Second World War to identify aircraft (Landt, 2005). It can be seen as an ‘electronic barcode—it can be used to identify a certain tag, associated product, or aircraft). “A RFID tag consists of a small integrated circuit attached to a small antennae, capable of transmitting a unique serial number a distance of several meters to a reading device in response to a query.” According to Juels et al. (2003). This definition is a definition of a passive tag. The difference between passive- and active tags is that active tags can send out their ID constantly without a reader ‘asking’ for it. A hybrid form also exists, the semi-active tags, which use batteries to run the microchip but not to communicate (Hu et al., 2011). Such an passive tag consisting of integrated circuit is very small and the largest part of an RFID tag is its antenna which is normally around 0.05 m × 0.05 m, but can also be as small as 0.4 mm × 0.4 mm, according toJuels et al. (2003) and Want (2006). Tags can be as cheap as $ 0.05/unit (Juels et al., 2003) but the RFID Journal (2014c) states that the price ranges between $ 0.07 and $ 0.15/unit. The integrated circuit (IC) contains the information and by the grace of the antennae this information can be transmitted or received, depending on the type of RFID tag. Tags can either be solely read or also have a write function (referred to as read-write tags).
The active RFID tags have their own source of power and can continuously emit a signal. Passive tags do not have their own power source and rely on the RFID reader to supply power (the workings will be explained in subsection 3.3). Because
passive RFID does not require a energy source they have an indefinite lifetime; due to simplicity they are also less prone to break down as opposed to active tags which are more prone to break down.6 Active RFID tags are much more expansive than the passive tags. Active tags cost about $ 25/unit according to RFID Journal (2014c).
Although the cost for RFID tags seem very straight forward these costs for tags cannot be extrapolated into the number of tags required; a fully functional RFID system has a lot of components; RFID Journal (2014b) states: “The cost depends on the application, the size of the installation, the type of system and many other factors, so it is not possible to give a ballpark figure. In addition to tag and reader costs, companies might to purchase middleware to filter RFID data. They will likely need to hire a systems integrator and upgrade enterprise applications, such as warehouse management systems. They might also need to upgrade networks within facilities. And they will need to pay for the installation of the readers. Not only do the readers need to be mounted, they need electrical power and to be connected to a corporate network. All of these factors are different for each deployment, depending on the application, the environment and so on.”
3.3 Physical Workings of a RFID Tag
For an RFID system to work there are always two components needed; a sender and a receiver (and an interpreter to interpret). Let us consider this in more detail now. The passive (or near field) RFID works due to a principle which is called Faradays principle of magnetic induction; a reader produces an alternating magnetic field locally. When the RFID tag is placed within this magnetic field it induces an voltage over the tag, this can henceforth be used by the tag to ‘create its own magnetic field. This secondary magnetic field can be picked up by the reader (Want, 2006). The near part of the near field sensing is a result of the frequency and the combination of distance to the source and the energy available. The range scales with the frequency, f,
rmagnetic ∼
c
2πf. (1)
As said it also relates to the distance to the reader-coil cubed this is due to the fact that the magnetic field propagates in three dimensions outward,
rpower∼
1
r3. (2)
Where the range, r, is perpendicular to the tag-coil its plane (Want, 2006).
We must now admit that there is also a far field type of RFID which, strictly speaking does not fit in our ‘near field sensing’-taxonomy. However, bearing in mind the goal of this assignment—to look for the application of RFID or near field sensing in the handling of containers in container terminals—and the shear scale of terminals we must take this type of RFID into consideration. The far field RFID
6
Offcourse this argument does not hold for the OV-chipkaart, since this particular RFID chip is very prone to breaking down as all users are now very aware.
uses a different—more complicated—method; namely that of back scattering. The workings described below are directly copied from Want (2006) and checked against Juels (2006): “An antenna with precise dimensions can be tuned to a particular frequency and absorbs most of the energy that reaches it. However if an impedance7 mismatch occurs it will reflect back some of the energy towards the reader which can detect the energy using a sensitive radio receiver.”
It is noteworthy that we did not speak of cameras or barcodes because they require a line-of-sight. Note that we have thus far considered electromagnetic forms of transmission and reception because they do not need a direct line-of-sight. To the observant reader it must now dawn that the light seen by a camera (or refracted by a barcode) is also a form of electromagnetic wave. Typically the wavelengths observed by a camera (visual light) and barcode scanner (visual and near-infrared) are between 380nm and 750nm (for visual and up to 3 µm for near-infrared (Weber, 1999). Typically the magnetic frequencies are between 100 MHz and 2.45 GHz which relates to the wavelengths;
λ = v
f, (3)
where v is the phase velocity and is—for electromagnetic waves—equal to the speed of light, c, which is 3 × 108 m/s2 (Cassidy et al., 2002). It thus corresponds to wavelengths of 3m to 0.12m; which are significantly larger than that of visible light. It is in here that lays the answer: both require a direct line-of-sight (!) but because the larger wavelengths are not fully absorbed (or reflected) by everyday objects and can therefore ‘see through different materials. In other words they do not need a direct line-of-sight8 in the visual spectrum; they do however in their respective spectrum.
The researcher or implementer of RFID technologies should pay close attention to the penetrability of radio frequency waves through the steel of a typical container (Steinecker, 2012). Ting et al. (2012) shows in the ‘penetration test’ that: ”It is found that the reader cannot read a tag behind the container. It means that the communication cannot pass through containers or internal tractors.”9
3.4 Identification of RFID Tags
The reader must now have a—more or less—clear vision as to what near field (and far field) sensing entail. To get a readout of the NF-tags a reader and a tag are required. If either one tag cannot be fully read or two tags are offered to the reader some extra actions need to be taken; these are both by means of software. The first—the decoding operation—is simply solved (dubbed singulation) but the second is a little more difficult (anti-collision). The identification of the different tags is extensively discussed in RFID essentials by Glover and Bhatt (2006).
7Impedance is orientation of a circuit with respect to the current when a potential difference
(voltage) is applied.
8We need to take the sight part literally. 9
They used a RCG-CR210 system, this operates at 2.4 GHz. However the issues described here are for aforementioned reasons expected in all systems.
Collisions are categorized in three types and explained by Han et al. (2014): • Multitag with single reader collision; these happen when two tags try to be
recognized by the reader. This can cause harm and lower readout speeds, resulting in delays.
• Multireader with a single tag collision; this happens when two readers try to readout the same tag. Multiple readers try to single out the the tag resulting in a ‘label interval condition error’.
• Reader-Reader collision; happens when to readers operate in the same fre-quency interval and cause interference.
The most common singulation and anti-collision procedures protocols are based on the Aloha protocol (Glover and Bhatt, 2006) and Han et al. (2014). A dramati-sation is taken from from Glover and Bhatt (2006) and can be found in Appendix A.
3.5 Safety and Security
In addition to understanding the physical workings the tags there is the increasing importance of safety and security knowledge. As the RFID tags become more widely used and in increasing variety of applications their safety measures should be accord-ingly—this is equally true for the use in terminals. If tags contain information on the goods stored and the price thereof it could potentially benefit wrongdoers .
Although there are guidelines for safety and security (such as: ISO/IEC (2000)) for RFID tags there are still a lot of problems with security as Molnar and Wagner (2004) suggest, Wired (2014) goes as far as saying that RFID will suffer from the same diseases as the early internet did. “Nobody thought about building security features into the Internet in advance, and now we’re paying for it in viruses and other attacks. We’re likely to see the same thing with RFIDs.” Since then Tsudik et al. (2008) has shown that there are still problems with secure pairing of a tag with a receiver for passports-tags, and others.
The main problem with security of RFID tags is that they contain a single unique identification (UID, or multiple static UIDs. The signalling of this UID is triggered by a card reader, this signal can henceforth—and with the right equipment—be copied or ‘cloned’. With an emulator this signal can thence be emitted to fool the reader in believing that the original card is produced. This is just one way of security breach, other methods are rewriting tags, overwriting data, eavesdropping, or erasing data. This means that—again with the right equipment—other information than the original can be stored on the tag (Molnar and Wagner, 2004). Fooling the system into believing that another tag (or coupled product) is checked in or out. In the last case (that of deleting) the information of the tag is erased crippling the infrastructure. This also means that he data is (mostly) unrecoverable.
More advanced tags are harder to hack (but also more expensive). Something that is called a symmetric-key tag is a one-way encryption that can seriously reduce the problem of cloning. A digital signature transponder by Texas Instruments is widely used (for instance the ExxonMobil petrol station pay tag or theft-deterrent
in almost all new cars (Juels, 2006). Bono et al. (2004) showed however that it was still possible to hack these systems using a ‘brute-force’ attack resulting in free gas or a crippled (i.e. unstartable) car. They suggested a harder to crack code consisting of a longer (adequate) key length of 128-bit; ExxonMobil has indeed confirmed their switch hereto (Wired, 2014).
Even more advanced systems exists, active tags, for instance, can be two-way encrypted and harder to hack therefor.
In a literature survey by Spruit and Wester (2013) he assessed the number of references to different types of ‘hacks’ and protection capabilities. The study is based on twenty-four academic papers and are shown in Figure 5. The solutions are ad hoc, and as mentioned before not hardwired into the system, making the system always prone to attacks. The most promising methods seem the ‘faraday cage’, ‘blocker tag’ and ‘RFID guardian’ but are all active systems or difficult to adopt and therefore quite expensive. Guizani (2014) confirms that 10 years after the Exxon mobile hack it still “quiet easy” to reproduce, clone and affect tags. He also suggests the same countermeasures as Spruit and Wester (2013) to solve the problems related to the above mentioned. Lehtonen et al. (2006) suggests a solution to equip tags with the possibility to note when they are being tampered with; this is repeated by Guizani (2014).
Figure 5: Threats for RFID systems ans possible ways of protecting the system; courtesey of Spruit and Wester (2013).
In the next chapter the implementation of the RFID technology in the container terminal will be explored. The data structure of such vast systems will also be discussed.
4
Information Technology Architecture
An information system is defined as the “complementary networks of hardware and software that people and organisations use to collect, filter, process, create and distribute data [. . . ]” by Jessup and Valacich (2008) and Bourgeois (2014).
In case of a container terminal (and this survey) this means the integration of RFID technology (hardware) with a data management system (software). We discern top-level software (software concerned with planning and optimizing) and low-level software (software concerned with discerning tags, the anti-collision protocols and singulation operations). This final chapter aims at showing how the current state of the “[. . . ] integration of information captured by RFID into terminal management system”10 is coming along.
For this we will start from the work of Ngai et al. (2011) since he gives the first self-proclaimed reference to the implementation of RFID in the physical environment of a container terminal.
So far we have discussed the physical environment of the terminal as well as the workings of the RFID tags and readers, this is the low-level hardware side. In addition we spoke about the low-level software which helped single out tags and manage collisions. This final chapter aims to show what has not been discussed jet. The high-level hardware side, the middleware and the edge service systems, and the high-level software, such as optimizations that can be gained as a result of RFID implementation.
4.1 Basic Structure
Glover and Bhatt (2006) zooms in to the generic parts in a RFID system. A generic RFID system should—at least—consist of the following parts:
• data center; • NFC tags;
• middleware (readers); and • edge information service.
This largely corresponds to the hardware-software dichotomy made by Jessup and Valacich (2008), and the description of a typical RFID system by Hu et al. (2011) complemented by the edge information services. Kwok et al. (2008) suggests a little more detailed list of basic components (namely: a data center, middleware, readers, antennae and tags). They agree, however, on the basic structure of a system. The list presented above holds for any application area (e.g. retail, transport, and smart card).
A high level schematic of an generic IT architecture is visually represented in Figure 6. Together with the earlier mentioned RFID technology and middleware the reader must be left with an idea of a complete information system for container handling on the basis of NFC.
Figure 6: High level schematic of an information technology architecture. (Based on Kwok et al. (2008), Glover and Bhatt (2006) and Jessup and Valacich (2008).)
4.2 Physical Implementation of RFID Technologies
Several researchers have tried to implement RFID technologies in the container ter-minal environment.
Ngai et al. (2011) is the first to combine the stream of information on RFID tech-nology and mathematical models with the implementation and information stream on container terminals. He calls the generic system a ubiquitous sensor network (USN) which is: “[. . . ] a network that enables users to receive the necessary information any time from anywhere by installing small wireless sensors that detect the surrounding environment [. . . ]”. The environment could be a logistics and transportation area; however, this is rare, he says. He deploys a system which uses differential global po-sitioning system (DGPS) to track locations and different techniques and machinery to track the containers. It is important to not that he does not propose to track individual containers but rather machinery and where it transports the container to. The tracking of individual containers is low-level tracking, whereas the tracking of machinery (from which container location is deducted) is high-level tracking.
In other words the NFC part is fulfilled by RFID technologies but is comple-mented by other equipment and middleware such as DGPS sensors. Ngai et al. (2011) suggests a system in which containers are registered as they board (or leave) a cer-tain machinery. These machines are tracked and the concer-tainer location is deduced (traced). Several different techniques exist to monitor equipment and subsequent containers; these techniques are mainly based on a combination of transponders, (D)GPS and RFID, according to Gharehgozli et al. (2014).
Ting et al. (2012) has researched the feasibility of applying RFID technologies in a terminal environment, he concluded that the technology still suffered from reliability issues (which is only 100% in the 5 to 10 meter range) and that external factors that will make the reliability drop are:
• change of weather;
• metal containers will affect RF wave communication; • not well-defined routes; and
• difficulties with installing equipment;
Although these downsides Ting et al. (2012) concludes that it is feasible and will “facilitate the operation of the terminal [. . . ]. So, the system is worth to implement in the container terminal. However, before deciding whether to implement a tracking system in the terminal, more experiments on different RFID equipment is necessary in order to sort out the best possibility.”
Hu et al. (2011) tries to incorporate the RFID technology into the current day—existing—terminals. In these these terminals, all too often, data is relayed via a gate operator punching in numbers (EIR), which increase the chances on an error. This process is very open to innovation and here a possibility lays, “we may decrease the workload in the gate of the container terminal and improve the effi-ciency in receiving the containers” he says. In contrast to Ngai et al. (2011), Hu et al. (2011) suggest to equip all containers with tags and all handling equipment and gates with readers. Figure 7 shows a schematic where to apply the sensing ma-chinery. In theory the equipment can be attached to any point, preferably a place where there is a free line-of-sight to the tag and on a position where the two are as close together as possible to get an accurate readout. This is an example of high-level tracking. A low-level tracking implementation is shown in Figure 8.
Hu et al. (2011) refers to work of Xie et al. (2007) in which this idea has been successfully installed in the Waigaoqiao terminal in China. In reduced the average time through the entrance gate from 70 seconds without RFID technology to 22 sec-onds with the implementation of these technologies. If this is indeed the bottleneck than potentially huge efficiency increase can be made.
Although this seems promissing Xiaohua and Hanbin (2011) shows that, with his new model for radio-wave propagation characteristics in a container terminal environment, a strong fading of the signal occurs. This can be mended by increasing send power or sensitivity of the receiving antenna.
A tool for assessing how these technologies (including the adoption of AGVs and other technologies) rank has been made by Nam and Ha (2001). He sets criteria for the evalution of different handling systems (Steenken et al., 2004).
4.3 Other Productivity Gains and Optimization
We have seen that RFID technologies can potentially benefit flow through time at gates or yield insight in whereabouts of the containers. Another field that could benefit is that of optimizing. Due to the newly gathered data new possibilities arise
Figure 7: A schematic image showing where to place sensing technology for a gate-based (high-level) tracking system, courtesy of Hu et al. (2011).
Figure 8: An implementation image showing where to place sensing technology for a low-level tracking system, courtesy of Xiaohua and Hanbin (2011).
such as ‘online-optimization’ which will be discussed. This becomes possible because more accurate and real-time data is available. (Other new possibilities consists of real time measuring temperature, humidity, etc and storing this information on the tag (Ngai et al., 2011).)
Kemme (2013) opts two different types of optimisation. The first is ‘classical optimization’ which he dubs ‘offline optimization’ which has all input data before optimizing The second is ‘online optimization’ where a new piece of information demands information. Because reality is erratic, decisions have to be made in very tight time-frames which have to be solved in real time, he says. RFID technologies could assist such an ‘online optimization’ with real-time data, which in addition could be more extensive than current information.
Grotschel et al. (2001) distinguishes the following general designs for ‘online optimization’ algorithms:
FIFO First-in-first-out strategy serves requests in order of appearance, efficiency issues are not regarded.
Greedy This algorithm serves the request next which—within the current state of the system—leads to the least cost (however this is defined).
Replan This algorithm computes the ‘optimal’ solution at a specific point in time. Every time new data becomes available the solution is re-computed; all sched-ules made before are re-planned.
Ignore This algorithms computes an ‘optimal’ solutions and starts executing; when performed it will make a new solution. The current schedule is not revised during execution.
These types of online optimization become possible by implementation of new technologies which could accurately display and relay real-time data to the main-frame.
4.4 Implementations
A system as described in the foregoing survey is in sorts implemented in the Port of Hamburg. The Port of Hamburg worked together with several different parties (T-Systems, Deutsche Telekom Innovation Laboratories, SAP and the Hamburg Port Authority) to create an elaborate ‘cloud’ based system. The backbone is formed by the Telematic One platform which is the online cloud based system. This enables the harbour to adopt different electronic technologies—such as RFID. (T-Systems, 2012)
In 2006 the Port of Hamburg started with testing RFID enabled containers (low-level) on the Hong Kong-Hamburg stretch. SAP (Systems Applications Products in Data Processing) has simultaneously developed its SAP Auto-ID, aimed at serving customers with end-to-end RFID integration in its network, according to. (Shippers, 2006)
Literature has not shown any other large scale adoption of the RFID technologies in terminals. This is also backed by Dempsey (2011), who sees opportunities but no widespread application.
4.5 Synthesis
All in all there are two major benefits to implementation of RFID in a terminal environment. The frist being that individual containers flowing though the terminal can quickly be identified, which is called the interactive part. The second is that this information can be relayed to the main ‘server’ or ‘mainframe’ which can incorporate the data to yield new and better optimizations. The visibility becomes more clear because data can now be real-time and the information can be more elaborate than before which makes the monitoring for the operators simpler. (Kia et al., 2000)
The information system (the combination of hardware and software used to col-lect, filter, process, create and distribute data) required consists of tags, readers, relay information as well as receivers, DGPS systems, and computers complemented
by edge information systems to process the newly gathered information. (Jessup and Valacich, 2008)
Several researchers have shown that this integration is indeed possible, although they also express the need for further investigation in order to overcome the problems with signal interference. (Xiaohua and Hanbin, 2011).
5
Conclusions
Maersk (2014) and Port of Rotterdam (2013) witness an ever increasing demand in container transport. As a result terminals have to process more containers every year, low visibility leads to congestion or idle equipment, according to Cheung and Ngai (2009) and Ngai et al. (2011).
The reader must discern the cheap passive tags from the more expensive active tags. Passive tags allow the same visibility in terms of information relay. However active tags offer an advantage, they can be more secure due to back-and-forth talking between sender and receiver as well as having a larger range.
Radio frequency identification technologies could solve the congestion problem. However several researchers, such as: Molnar and Wagner (2004), Tsudik et al. (2008), Spruit and Wester (2013) and Guizani (2014), have shown that RFID tags are still easy targets for hackers and that countermeasures are costly and impractical. Also the interference of the containers steel with the radio signal is pointed out by Xiaohua and Hanbin (2011) and Ting et al. (2012).
Research by Ngai et al. (2011), Hu et al. (2011) and Ting et al. (2012) into the implemation of RFID in a container terminal show that it will yield increased production as a result of decreased handling time of containers and increase produc-tivity as a result of possibility of use of ‘new’ online (i.e. real-time) optimization algorithms.
In terminals such as Hamburg the implementation of a cloud-based system has proven to make RFID adaptation a feasible alternative for the man-handled systems that are in place nowadays. These adaptation however have proven to be a long road to success, judging from Shippers (2006) and T-Systems (2012).
6
Recommendations
In this final part I will recommend future steps that can be taken in order to get a better understanding into the adoption of RFID in a container environment or points that I feel are understated in literature. The recommendations are my own, they are a combination of things ‘missing’ in literature as well as inter- and extrapolation of information found.
My recommendations are as follows:
• Before RFID technologies are applied full-scale an investigation into the will-ingness of all container terminals into the adoption of these systems needs to be made. This system works best if all terminals world wide adopt these tech-niques. If just a portion of containers is equipped with RFID tags than a hybrid version—with operators and tag scanners—still needs to be in operation. • Although RFID shows potential it has also shown big problems relating to
security. Other systems which are less prone to hacks and attacks should be considered. Even if hackers do not want to steal information they are very capable of crippling a system with RFID technologies. The low-security level of RFID is pointed out numerously by authors, however no mention of this security issue is found in the ‘logistics’ papers’
• A large scale test with RFID enabled terminal equipment and containers should be done in order to get an idea of real feasibility. In literature only small scale implementations are shown; that new problems (that require solving) arise when a full scale test is done seems obvious.
• Investigation into the cost difference between high-level and low-level should be performed. The low-level tracking might fully eliminate the use of per-sonnel whereas the high-level might be more cost efficient in terms of capital expenditure; research has to show.
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