Agent/Space-based Computing and RF Memory Tag

Interaction

Joni Jantunen, Ian Oliver, Sergey Boldyrev and Jukka Honkola

Nokia Research, It

amerenkatu 11-13, 00180 Helsinki, Finland

Abstract. As devices become more ubiquitous and information more pervasive

technologies such as Semantic Web and Space-Based computing come to the fore

as a platform for user-interaction with their environment. Integrating technologies

such as advanced RF memory Tag with mobile devices and combining this with

computation platforms such as those supporting Semantic Web principles pro-

vides for the user innovative and novel applications.

1 Introduction

The integration of mobile devices, RF memory tags and semantic web style information

sharing and management will open new opportunities for the ad hoc gathering, sharing

of information and for more interactive applications built on top of these concepts.

RF memory tag systems will have the ability to store large quantities of informa-

tion coupled with high-bandwidth radio connections and even contain local processing

capabilities. Mobile devices, such as mobile telephones, have access to ubiquitous con-

nectivity solutions, eg: WLAN, GSM, UMTS networks, as well as sophisticated media

and processing capabilities as well as many local sensors such as GPS etc.

Semantic Web technologies provide canonical information representation formats,

in particular XML for the representation, RDF for the expression of semi-structured,

linked and linkable information and languages such as OWL for the speciﬁcation of

those structures. This allows much easier integration and interoperability between ap-

plications, agents and devices through standardising many features and providing a ba-

sis for reasoning technologies leading to, at least, weak-AI capabilities.

Combining these technologies together provides a platform for highly interactive,

viral information sharing applications that can be applied in many situations: such a

platform has been implemented as in [10]. For example: mass memory tags are used as a

distribution point of information in a certain locations such as ofﬁce or shopping center

information points, news stands, tourist attractions etc; even individual physical items

can be tagged - an application particular relevant in the medial sector. Applications of a

system would provide enahancements to existing service-oriented technologies.

In this paper we describe the technologies and an implementation which leads to

framework that supports such applications and interactions. Firstly we provide descrip-

tions of the technologies, then an overview of the types of applications with examples,

then a discussion on a speciﬁc interaction case which highlights particular interesting

areas of the RFID-Device-Space interaction and ﬁnally a discussion of the future direc-

tion and issues of this technology.

Jantunen J., Oliver I., Boldyrev S. and Honkola J. (2009).

Agent/Space-based Computing and RF Memory Tag Interaction.

In Proceedings of the 3rd International Workshop on RFID Technology - Concepts, Applications, Challenges , pages 27-38

DOI: 10.5220/0002172900270038

 SciTePress

2 Background

We focus on the integration of three major technologies: the Semantic Web, RF memory

tags and mobile devices. Within these categories we specialise on the notion of ‘Smart

Spaces’, the distribution and integration of information and a particular mass-memory,

high-bandwidth form of RF memory Tag.

2.1 Semantic Web and ‘Smart Spaces’

The Semantic Web [13] is a vision for the improvement of personal computing through

the exposition and sharing of information based upon common representation formats,

ontologies and semantics. The idea is that information would become globally ubiqui-

tous and interoperable.

However much information is not ubiquitous in the global sense; it is personalised,

hidden, private and is interpreted locally - this information tends to be the personal,

highly dynamic information that one stores about oneself: contact lists, friends, media

ﬁles, ‘my’ current context, ‘my’ family, ‘my’ home etc and the interweaving and link-

ing between these entities through ad hoc personal structures.

To address this issue we have implemented a system based around larger, more user

or personal focussed structured which we term ‘Smart Spaces’ [14]. Within a ‘Smart

Space’ (or just space) a user can encapsulate all of their information and interact with

that information according to their personal semantics and needs.

Spaces have the ability to be distributed across the user’s devices (mobile phone,

media center, personal computer etc) as well as more centralised providers. Synchroni-

sation between these distributed, individual repositories of information is asymmetric to

address device and network capabilities as well as the user’s needs in terms of security

etc.

Interaction with spaces is nominally by ‘agents’ which encapsulate ﬁne grained

functionality which themselves may be distributed across any number of devices that

have access to the user’s space. Spaces themselves can interact through merging and

projection enabling larger spaces to be constructed either on permanent or temporary

basis.

Further interaction between users is enabled through one user granting access to

their space (or spaces) to another user’s agents or even by directly sharing the contents

of their spaces through the asymmetric distribution mechanisms.

A space can transcend over many of the user’s devices leading to the distribution of

information and queries upon that information. For any agent accessing this information

the physical location of it and the information is irrelevant: an agent sees the ‘totality’

of all information in that space. This requires sophisticated distribution algorithms that

actually preserve a degree of assymetry of information depending upon the stability,

connectivity and other properties of a particular information repository.

2.2 From Rﬁd to Rf Memory Tags

Radio frequency identiﬁcation (RFID) technologies have been used for decades in ex-

tensive variety of applications [1]. In the simplest RFID applications the tags embedded

into objects only provided 1-bit presence information when exposed to the electromag-

netic ﬁeld transmitted by a reader. Identiﬁcation of tags with individual ID codes started

from active tags and read only memories and it has become commodity also for passive

tags. Recently, especially the mainstream development of passive RFID technologies

has been steered by applications such as logistics [2], and mobile payment [3]. In these

applications the tags may include also some amount of non-volatile memory. Thus, a

bi-directional communication link between reader and tags is required to enable also

writing of data to tags instead of read-only access. Recently, respective reader capabil-

ities have been also integrated into mobile phones [4]. That provides a possibility to

use RFID tags as part of Smart Space applications by using mobile phone readers as a

gateway.

One development branch of RFID technologies is focusing on applications where

passive RF memory tags will contain increasingly large non-volatile memory capacity

(in scale of mega- to gigabytes) [5]. Such tags would enable storage of digital content

exactly to the point where it is used e.g. into objects and physical locations. This ap-

proach is totally opposite to the network databases traditionally used in RFID systems

where tags may store only a link to the databases. The visions behind this research are

based on the foreseen development trends especially on the ﬁeld of non-volatile mem-

ory technologies according to which the power consumption, physical size and price of

(non-volatile) memories are continuously decreasing. TSuch his enables development

of passive RF memory tags which can be accessed wirelessly, for example, with mobile

phones and which can be used as ubiquitous storage capacity in Smart Space applica-

tions.

In RFID systems the physical interaction is usually based on back-scattering of

narrow-band RF signals [7]. The reader device provides a continuous wave signal which

is used by the tag to extract supply voltage.

The communication from the tag to reader is possible thanks to modulation of back-

scattered signal from the tag, whereas the communication from reader to tag can be

done for example with simple amplitude or phase modulation methods respecting the

power extraction needs in the tag. Small memory capacity can be implemented with

EEPROM and the whole functionality is usually controlled by a simple ﬁnite state-

machine (FSM). However, when the storage capacity of tags increases signiﬁcantly

back-scattering method based on a single frequency band may be insufﬁcient to achieve

data-rates high enough. According to current regulations wide enough frequency bands

are not available on low frequencies and the efﬁciency of wireless power transfer de-

creases on high RF frequencies. Thus, either data-rate or communication range is some-

what limited. Therefore dual-band systems have been proposed for data centric Ambient

Intelligence (AmI) applications, such as, the ones used in Smart Space context [6]. An

exemplary (complete) block diagram of an RF memory tag is presented in Figure 1.

In such a system one frequency band is dedicated for wireless power transfer and one

wider band for high data-rate communication.

Section 3 categorizes groups of interactions between RF memory tags and Smart

Spaces. Depending on the category the required computational power of tag may range

from mere memory access (a simple FSM is enough) to hosting of an agent or a space

(requiring MCU or even CPU). In the two ‘classic’ ways it is sufﬁcient that the tag

is capable of transferring the data deﬁned by the reader with the highest possible efﬁ-

ciency to achieve user-friendly interaction. The reader device is responsible of deﬁning

which data is read and/or written, and basically in the tag there is no need to process

the content itself. Even the ﬁle-system can be maintained in the reader side if it is ﬁrst

copied from tag to reader in the beginning of interaction and then updated version is

written to tag after the payload data in the tag has been modiﬁed.

Fig. 1. Block Diagram of RF memory Tag.

In more sophisticated cases where tags are capable of hosting an agent or running a

space it may be necessary to have sufﬁcient processing capabilities in the tag itself. If

fully active tags are excluded from the study, to achieve easy and low cost maintenance,

the remaining alternatives are fully passive tags and semi-passive tags. In the passive

solution the data is processed fast in the tag during the reader-tag interaction. In the

semi-passive solution the data is processed over a long period of time (as a background

process) by using a dedicated power source e.g. the power harvested from the environ-

ment and only the high data-rate communication requires wireless powering provided

by the reader. In semi-passive case the tag may also function as a data-logger by slowly

collecting a huge amount of samples from a low-power sensor over a long measure-

ment period. However, these applications require extremely low power consumption

what comes to the memory accesses, data processor and sensors but also required data-

rate is extremely slow.

Altogether, the ongoing development on many technological ﬁelds will in the future

enable utilization of RF memory tag systems in Smart Spaces. Actually, Smart Space

applications may become one of the main drivers for the technological development of

aforementioned RF memory tag systems.

2.3 Distribution

The scope of distribution and corresponding infrastructures in case of RF memory tag

systems can be analysed in terms of two areas:

– physical environment, e.g. associating of the RF memory tag with direct or indirect

functionality provided by the physical environment, and

– ubiquitous device architecture, e.g. impact to the internals of a particular mobile

device

Considering further, the following can be seen:

– RF memory tag is dumb memory block and has just mechanisms for bidirectional

wireless operations (read/write)

– RF memory tag has enough computational power on board, but still external power

is needed, or it can be provided on a volatile basis

Therefore, the range of potential application can be variate from simple “just-in-place”

and “just-in-time” ﬁle storages coming to distributed ad hoc storage systems [9] and

going beyond asynchronous computation engines. Projecting such features to the Smart

Spaces architecture RF memory tag system enables use cases when information re-

lated to the particular physical environment can be delivered in-place on-demand or

even by estimation, in a very power and computation efﬁcient manner. By saying “de-

livered” the whole process of extraction, recovery, storing and computing should be

understood. Since using RF memory tag system it is feasible to produce a distributed

snapshot of Smart Space which is tied with the particular physical environment by stor-

ing the run-time environment and corresponding contexts with data/information within

the RF memory tags, it also becomes possible to revoke the system once it would be

demanded by any user. In other words the distributed process of booting, suspending

and resuming of the Smart Space now becomes more ﬂexible, reliable and less physical

context dependant.

Smart Space application infrastructure beneﬁts from RF memory tag system as well.

Since RF memory tags infrastructure provides distributed grained approach for execu-

tion context and information handling, Smart Space application can be constructed by

traversing the RF memory tags and retrieving demanded parts of execution context and

corresponding information.

In terms of ubiquitous device architecture, as it is presented by Figure 1, RF mem-

ory tag system can enable computationally constraint device with memory extension,

distributed memory architecture, or, rich context data analysis and corresponding infor-

mation generation, which then can be uploaded to RF memory tag system.

The problem of memory management (both, execution and mass memory) in dis-

tributed environment, when substantial amount of the devices are using RF memory tag

system technology, converges to the efﬁcient and sustained context execution which is

essential part of whole computing environment, such as Smart Space. Especially be-

cause of high dynamics and constrains the amount of memory on board the mobile

devices in Smart Space.

The approach of efﬁcient and sustained distributed memory utilization by means

of RF memory tag illustrates the solution of such problem. Consider the computing

environment where memory is integrated with RF memory tag based architecture, and

several distributed memory modules are dispersed around the Smart Space(s). Therefore

they are considered as one stackable memory unit by means of corresponding combi-

nation of memory blocks of the environment.

Putting environment where memory is integrated with RF based memory tag ar-

chitecture and several distributed memory modules are dispersed around the Smart

Space(s). From the Smart Space perspectives and corresponding functionality is pro-

vided by distributed RF memort tag based infrastructure, at least following cases de-

scribed in section 3 can be seen.

3 Interaction with Tags

In this section we describe the various modes by which spaces and agents interact with

the RF Memory tags. We deﬁne four categories:

– Agents read from Tag

– Agents write to Tag

– Agents on Tag

– Space on Tag

The ﬁrst two categories are the ‘classic’ ways of passively interacting with a tag and

constitute simple information retrieval and sharing. The third and fourth cases involve

much more ‘active’ interaction based requiring speciﬁc features of the agent/space ar-

chitecture. We explain these in the following sections with an addition discussion of the

actual physical interaction between devices and the RF memory tags.

3.1 User Interaction

As mentioned in the previous section, in the context of Smart Spaces many new re-

quirements for the future enhanced RFID-like technologies are set. In Smart Space

environment also the user interaction is in a critical role [6] since the fast data connec-

tion is enabled only if user voluntarily accesses RF memory tags. Therefore the system

must be fast, ﬂexible and reliable in addition to many other requirements. The need of

bi-directional high speed data transfer is obvious to achieve convenient user experience

when the storage capacity of tags increases. Flexibility can be understood as a require-

ment for practical communication range. Typical physical interaction is shown in ﬁgure

Fig. 2. Physical Interaction of Device and RF memory Tag.

From user’s perspective it is needed especially to allow intuitive and convenient control

through user interface of a mobile reader. Figure 3 presents a situation where mobile

phone is used to interact with a tag which is part of a Smart Space. As can be expected,

the communication range must be long enough to avoid need for accurate pointing of

reader to tag in varying usage conditions. The communication link should also allow

movement of the reader while the user makes selections through the user interface.

Reliability of the user interaction can be understood as the quality of data transfers i.e.

low probability of errors on different levels but also as security and privacy aspects since

obviously users cannot tolerate such infringements if the content stored to RF memory

tags is private.

3.2 Agent Interactions

The “simple” read case is useful for applications where the tags provide relatively static

local information, for example, maps, positioning information or even marketing in-

formation such as might be found in a shopping mall style scenario. One existing ap-

plication is that found in museum environments [11, 12] and this is currently being

investigated as an initial deployment of the technology described here.

The “simple” write allows the user to write to the tag. This enables sharing of user’s

information through copying information from the user’s space to the RF memory tag.

This case would be almost invariably used in conjunction with the read case. Typical

applications here might be viral sharing of media or other information, for example,

highly localized blogging and messaging. These classic cases are shown in ﬁgure 3.

RF Memory Tag

Information flow −−−>

RF Memory Tag

<−−− Information flow

Fig. 3. Classic Interaction.

The third case shown in ﬁgure 4 requires the tag to have some computational capabili-

ties. When the device with the reader is presented to the tag, it activates agents on the tag

itself which then either request to join the user’s space or are invited to the user’s space

for the duration of the time while the reader is in contact with the RF memory tag. The

agents on the tag may provide additional reasoning or other data gathering/processing

operations as well as supporting the classic read and write use cases described earlier.

The agents can access a Smart Space with ﬁve basic operations:

– Insert: Insert information into the Smart Space.

– Remove: Remove information from the Smart Space.

– Update: Update the information in the Smart Space. This is effectively an atomic

remove and insert combination.

– Query: Query for information in a Smart Space.

– Subscribe: Set up a persistent query in a smart space. A change in the query results

is communicated to the subscribing agent.

SIB

RF Memory Tag

Agents running "locally"

Agents copied to run "locally"

SIB

Agents running "locally"

Agents run at tag

<−− Information flow −−>

RF Memory Tag

(AmI)

Fig. 4. Agent Interaction.

There are two individual cases to be considered here. First, where the RF memory tag

has some computation capabilities, i.e. a CPU or MCU, and second, where the compu-

tation has to be made on the reader.

The ﬁrst case is conceptually more straightforward, as the agents on the RF mem-

ory tag are executed outside the mobile device and need only access to the information

stored in the space. This access may be limited by the space and thus the agents need

not to be particularly trusted.

The second case would involve running arbitrary code on the mobile device, and

presents a lot of additional problems to solve relating to security etc. Standard mech-

anisms related to e.g. downloading applications are probably not applicable, as the re-

quired interactions from the user should be kept to a minimum.

It should be noted that even as these cases differ on the implementation level and

required infrastructure, but the end result regarding the information content in the space

is the same.

This kind of “Agents on Tag” concept provides means to enhance the information

content stored on the mobile device by adding localized, positional knowledge to the

space. Furthermore, they may also utilize whatever information is available to them in

the space, perhaps creating a history of interactions for subsequent processing etc.

3.3 Space Interactions

The fourth case is particularly interesting as it provides temporary (or even permanent)

additional information for the user without resorting to agents. Any particular mobile

device is part of Smart Space environment as it is presented above, in Section 2, and

RF memory tag based infrastructure constitutes another Smart Space entity. This case

can be addressed by any two (2) Smart Spaces merge process. Similarly to the previous

agent interaction case there exist two distinct modes of operation, this time however

referring to the location of the broker that enables the space; these are visualised in

ﬁgures 5 and 6.

SIB SIB

RDF

Store

RDF

Store

(Mobile) Device

RF Memory Tag

distribution protocol

Fig. 5. Space Interaction (Tag hosting SIB).

SIB

RDF

Store

RDF

Store

(Mobile) Device

RF Memory Tag

distribution protocol

Fig. 6. Space Interaction (Tag not hosting SIB).

We would stick to the cases when RF memory tag based infrastructure is created by

manageable and non-manageable RF memory tags, meaning that the computational ca-

pabilities of any RF memory tag are extended, e.g. with CPU or MCU, and limited,

e.g. without CPU or MCU. To guarantee sustained data on the board of RF memory tag

there are facilities provided by memory chip and RF control. To provide mechanism for

proper allocation, management and removal of data, a recognizable list of data, ad hoc

data management system is used.

Let us concentrate more on the technical details of the process when such mobile

device would found any RF memory tag. To establish communication channel which

should be considered of ad hoc type, mobile device should scan the environment to get

the conﬁrmation reply from any RF memory tag.

Once the physical connection is up and transport protocol is running, and RF mem-

ory tag can be mounted to be used as a storage space or it can begin to act as another

Smart Space entity. To simplify our further considerations, let us denote the mobileThis

work has been partially funded by TEKES ICT SHOK DIEM (www.diem.ﬁ) and EU

FP6 MINAmI projects (http://www.fp6-minami.org/). device’s Smart Space as SS1, and

the RF memory tag based Smart Space as SS2.

In case if RF memory tag was mounted as a plain storage space it can be used as an

extent where, existed, SS1 keeps the data in raw (as it would be in case of any grow-

able ﬁlesystem volume). And, therefore, any POSIX like procedures could be applied

to gain the access and to store/remove the data on such volume. However, it is not really

beneﬁcial way in case of Smart Space environment.

Since one of the main points to use the Smart Space environment is to provide in-

teroperable interaction between most of computing environment by exchanging high

abstraction level information, by means of Smart Space’s deﬁned Insert, Remove, Sub-

scribe, Unsubscribe and Query primitives and utilizing a certain reasoning mechanism

over the different sets of that information, to extract the necessary one, the level of in-

teraction between mobile device and RF memory tag is pushed up to high abstraction

level of information exchange. Therefore, the rules of Smart Spaces merging process

are applied. Those can be seen within the following ﬂow:

1. let us assume that SS1 represent an active entity from energy perspectives, therefore

it is assumed to be as a leading party (so deﬁned master SIB or mSIB) which is

driving the merging process as such

2. even SS2 represents a passive entity from energy perspectives, it might have either

suspended SIB or RDF store facilities that can be merged with or utilized by the

corresponding SS1 facilities, thus, one of the following can take place:

(a) mounting as RDF store to SS1 facilities, providing passive information extent,

meaning that reasoning over that extent should be provided by SS1 facilities

(b) communicating as SIB-to-SIB, providing active information extent, meaning

that reasoning over that extent can be provided by resumed SS2 facilities.

3. invoke SS2 to Join the SS1 by means of Join/Leave message exchange and corre-

sponding Heartbeat message, to complete a handshake procedure

4. open communication as SIB-to-RDF (store) or SIB-to-SIB

5. prioritizing Query, Subscribe, Unsubscribe, Insert, Remove primitives to be issued

over the RF memory tag based information extent

6. prioritization is driven by reasoning over either the information extent provided by

SS1 or by SS2, thus the importance factor should be taken into account to leverage

the ﬂow of any needed information

7. proceeding with information exchange, this can be seen as a scheduler loop over

the particular primitives queueThis work has been partially funded by TEKES

ICT SHOK DIEM (www.diem.ﬁ) and EU FP6 MINAmI projects (http://www.fp6-

minami.org/).

8. ﬁnalizing communication as SIB-to-RDF (store) or SIB-to-SIB

9. leaving SS2 by Leave message from SS1 or invoking SS2 to send Leave message,

suspending it due to the passive mode

– any accidental power loss, which can be only due to the communication loss

(due to the nature of RF memory tag infrastructure), is accounted by transac-

tional model of any operations

Recombining cases above, to the better extent, a certain amount of agents could be

stored at RF memory tag infrastructure as well. And, once SS2 is resumed, agents are

retrieved from RF memory tag infrastructure along with information extent and the

physical context dependant application in merged SS1 and SS2 entity is assembled.

Logical ﬂow above illustrates a strong potential of RF memory tag based infrastructure

as Smart Space environment from the hardware perspectives. Therefore the cases above

should not limit the scope of distributed RF memory tag infrastructure.

4 Issues

Any interaction in this kind of environment has security and in particular privacy issues.

Because of the shared and thus viral nature of the information, the spread of incorrect,

bad or otherwise information is made relatively trivial. There do exist methods for trust

and policy but these still have to gain widespread acceptance.

One particular aspect is the provision of location and temporal information - be-

cause of the physical nature of the devices we can trivially infer location and the point

in time when the interactions took place.

The trust of such a system ultimately resides with the users and the overall manage-

ment of the information being interacted with and provided. However given the rise of

social networking, microblogging and the very basic need to share information, many

of these issues are not addressed there either. Nevertheless provision of security mech-

anisms such as authentication, encryption, private space and persistence etc can help in

such matters.

Despite of these issues the beneﬁts of such a mechanism for the user are tangible

and speciﬁcally in the areas of marketing, advertising and the provision of speciﬁc and

highly targetted temporal and location aware information.

Other concerns include the semantics and interpretation of the information con-

tained within the various spaces - a detailed discussion of these issues and some of

the solutions which are being implemented and investigated as part of the described

architecture and system can be found in [15–18]

5 Conclusions and Future Work

In this paper we have introduced and analyzed a concept where RF memory tags form

an extension to Smart Space infrastructure. Also most of the fundamental requirements

set for RF memory tag systems in such a context have been covered. In the present work

we have focused on interactions between the Smart Spaces and one individual tag.

The agent/space based system described in [10] provides a distributed infrastructure

for context gathering; while the agents themselves provide end-points for service usage.

Such services include those as provided by, for example: Nokia’s OVI

. Sharing through

physical access points such as RF memory tags provides additional and more novel in-

teraction with these services. This conclusively supports the trend towards context gath-

ering both in physical and virtual environments coupled with existing service-oriented

paradigms and building future information management and sharing approaches.

The future work will further extend the concept so that a population of tags forms

a platform for smart-space applications. This means that the SIB is implicitly shared

among the population by scattering copies of collaborating agents to the tags. In other

words, the tags collaborate with each other and form a SIB but due to the sporadic na-

ture of the processing capabilities and communication link enabled by the readers, the

tags have to rely on transfer of sporadic messages between each other.

Acknowledgements

This work has been partially funded by TEKES ICT SHOK DIEM (www.diem.ﬁ) and

EU FP6 MINAmI projects (http://www.fp6-minami.org/).

www.ovi.com

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