Wiberg M. - The Interaction Society[c] Practice, Theories and Supportive Technologies (2005)(en)

304 Henfridsson, Wiberg, Lindgren & Ljungberg

Chapter XII

SeamlessTalk:

User-Controlled Session Management for Sustained Car Conversations

Ola Henfridsson

Viktoria Institute, Sweden

Mikael Wiberg

Umeå University, Sweden

Rikard Lindgren

Viktoria Institute, Sweden

Fredrik Ljungberg

IT University of Göteborg, Sweden

Abstract

This chapter approaches sustained car conversations across mobile phones and in-car phone resources as a session management problem. Addressing this problem, the chapter outlines a session management model for user-controlled media switches during ongoing phone conversations. The model makes a distinction between the user and the infrastructure levels of session management. To illustrate and validate the rationale of the model, the chapter presents an in-car mobile phone

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hands-free system, SeamlessTalk, developed to support sustained car conversations. The user-controlled session management model contributes to current research on session management by addressing the explicit/ implicit session management dichotomy in multiple media situations.

Introduction

A considerable portion of all mobile phone calls is made in car contexts (Koslowski, 2002). While the car context involves novel session management considerations, little has been done to specifically support sustained car conversations. We refer to sustained car conversations as telephone calls supported by whichever phone resource suitable for the ongoing activity of approaching, driving, or leaving the car.

Even though previous empirical studies acknowledge the ongoing nature of conversations (Whitaker et al., 1997; Wiberg, 2001a) and the frequency of media switches during these ongoing conversations (Nardi et al., 2000), however, media switches between mobile phones (brought into or out of the car) and in-car resources are poorly supported by current in-car conversation systems. This is both a convenience and a safety problem. First, considerable overhead work is required for transferring a call to the in-car phone resources when entering the car for driving. In order to use the in-car phone resources (such as in-car screens and dashboard buttons for phone manipulation), the call must be ended and restored using the in-car phone. Second, as Salvucci (2001) outlines, the car is a perceptually demanding and dynamic place. Secondary tasks, such as talking on the phone, must be subordinated the primary task of driving the car. The safety hazards of mobile phone use are widely reported (Brookhuis et al., 1991; Redelmeier & Tibshirani, 1997), and it can be suggested that the lack of support for media switches is part of that problem.

In this chapter, we approach seamless car conversations across media platforms (i.e., mobile phones and in-car resources) as a session management problem. Session management within CSCW refers to the process of starting, stopping, joining, leaving, and browsing collaborative situations (Edwards, 1994; Kristoffersen & Ljungberg, 1999; Wiberg, 2001a). While this research focuses on session management on single media platforms (e.g., Edwards, 1994), however, it does not address sustained media switches during ongoing sessions.

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To address this problem, we have developed a session management model for supporting user-controlled media switches during ongoing phone conversations. The model is illustrated and validated by a car conversation system prototype, SeamlessTalk, designed to increase convenience and safety. Based on a use case developed according to Caroll’s (2000) task-artifact cycle, we demonstrate how SeamlessTalk addresses the convenience and safety problems of car conversations. The user-controlled session management model contributes to current research on session management by addressing the explicit/implicitsessionmanagementdichotomyinmultiplemediasituations.

Session Management

Single-Media Session Management

The research on session management ranges from empirical work studies (e.g., Kristoffersen & Ljungberg, 1999) to the implementation of new session management mechanisms (e.g., Patterson et al., 1990). The majority of the development-oriented research on the topic aims at reducing, and ultimately removing, the work required by users to handle sessions as such. Edwards (1994), for instance, notes that many collaborative systems are applicationcentered rather than environment-centered [See Kristoffersen (1998) for a review of session management in collaborative systems research]. This fact typicallyleadstonon-standardizedandinflexiblesessionmanagementcausing a significant amount of overhead work for the user. While this overhead work can pay off in situations where there is a certain degree of formality, Edwards argues that it can be detrimental to more informal, spontaneous, or lightweight collaboration. Addressing this problem, Edwards presents a session management model, referred to as implicit session management, for convenient establishment of new sessions in serendipitous collaboration. Using so-called activityinformation,asessionmanagementserviceisdesignedtoautomatically detect potential collaborative situations and take appropriate action.

As illustrated above, session management is typically viewed as a question of automation.Accordingtotheempiricalstudiesonthetopic,however,thisisnot necessarily applicable in practice, simply because there are so many situations where users do not want to join together with another person accessing the same document or entering the same place. Collaborative systems such as

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Montage (Tang & Rua, 1994) and the Interaction Manager (Ljungberg, 1999) provide session management mechanisms that seek to reproduce how people establish interaction in the real world. In the case of Montage, for instance, the user can set a door icon to indicate the desirable accessibility (Tang & Rua, 1994). If the door is shut, then the user is busy, and so on. The idea is simply that the user, when busy, could close the door icon, thereby reducing the risk of being interrupted by less important sessions. The door icon is, of course, a simplification that may not entirely be based on the valid assumptions of how people set up collaboration in real life (Kristoffersen & Ljungberg, 1999). Nevertheless, it reflects the ambition to provide session management mechanisms controlled by the users, as opposed to the systems.

Multiple-Media Session Management

Whiletheautomaticviewonsessionmanagementisthedominatingrationalefor single-media applications, this view is even stronger when it comes to media switches during ongoing sessions (e.g., American National Standard for Telecommunications, 2001). The standard approach to media switches is to let a system automatically hand over a session from one platform to another (Buford et al., 1998). As implemented in mobile phone networks, for instance, handovers are executed automatically when the phone receives a better signal from another station (sometimes denoted as ABC or “always best connected”).

In what follows, we illustrate how the automation view in multiple-media session management can be increasingly problematic on the user level. Considerthefollowingexamples:

Example 1: Within a few years, people are likely to subscribe to several wireless networks such as W-LAN, W-CDMA and GSM. W-LANs cover “hotspots,” W-CDMA the entire city, while GSM may be the only networkavailableinthecountryside.Inpart,thesenetworkswillcoverthe same areas. For example, users will be able to use GSM in the city. In such a situation, they will probably not want the mobile terminal to select network connections automatically. If the GSM network has enough bandwidth for your phone call, then why use the more expensive W- CDMA? Most people would probably want to continue the phone conversation using the (less expensive) GSM network.

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Example2:ItisincreasinglycommontouseW-LANsintheoffice,whichopens up new possibilities to have mobile Internet access. For example, it simplifies the task to provide handheld computers with useful content. Consider that you are in the office and start to download MP3 files. In this situation, the question is whether you want your handheld computer to continue to download music using the GSM or W-CDMA networks when leaving the office (recall the ABC principle)? Probably not, since it would cost you or your employer too much. Thus, you probably want the downloadtointerruptwhenleavingtheoffice.Likewise,youmaywantthe download to resume when you get back to the office, because then you have inexpensive wireless network access again. It is important to note, however, that in other situations (perhaps when important and timecritical documents are downloaded) you might want the download to continue using the GSM or W-CDMA networks when leaving the area with inexpensive network access.

As these examples show, automatic session management is problematic in that it is difficult for designers to implement rules that apply to all use situations. Whereas automatic media switches can be convenient in terms of the limited overhead work required, they can also be ill suited to the specific situations in which users find themselves.

Research Method

The research presented in this chapter was conducted as a collaboration project involving academics at the Viktoria Institute and practitioners at a car manufacturer(SaabAutomobile),amobiletelecommunicationsnetworkcompany (Vodafone), and a systems integrator (Mecel). We used the principles of the “task-artifact cycle” (Carroll, 2000). Intended to be a mediating structure between development processes and technology-in-use, the task-artifact cycle helps generating the requirements that can seed system design. More specifically, the rationale of this cycle is to capture and structure user requirements of a system by identifying the use cases and detailing all the scenarios that users will perform (within these use cases). A use case can therefore be described as a collection of possible sequences of interactions between the system and its potential users.

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Session Management for Car

Conversations

A Car Conversation Use Case

In order to reach an understanding of the proposed use context, we have developed the following use case based on Carroll’s (2000) task-artifact cycle. The actors involved in the use case are a driver and a passenger.

The driver and a friend enter the car while the driver has an ongoing call on his mobile phone. While seated the driver transfers the call to the in-car phone system for convenience and safety reasons. They start driving, and after a while the driver’s conversation shifts to a discussion about personal matters. Due to privacy reasons, the driver transfers the call from the hands-free system to the mobile phone. After a couple of minutes he terminates the call. A few minutes later, the driver initiates a new call using the in-car phone system. They finally reach their destination, but the driver wants to sustain the conversation. While leaving the car, the driver transfers the on-going call to the mobile phone.

As illustrated above, the situated nature of a mobile phone conversation can be handled by user-controlled media switches. In the use case, we can see how media switches between the mobile phone and in-car resources can facilitate bothsafedrivingandconvenientcontextswitching.Existingin-carconversation systems cannot do both. Either the user (approaching the car) must terminate the call on the mobile phone and restore the conversation using the in-car phone, or he must face the danger involved in sustaining the call on the mobile phone while starting to drive the car. Moreover, media switches can support privacy by allowing switches initiated by the user in view of changing conversation topics.

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Introducing a User-Controlled Session Management

Model

Based on the literature review and the use case, we below propose a usercontrolled session management model for supporting human conversation that includes several media switches. The central idea of our session management modelistodistinguishbetweentheuserandtheinfrastructurelevels.Automatic handovers between platforms on the infrastructure level are important for supporting interoperability and interconnectivity. On the user level, however, we argue that it is crucial that the user controls how and when a media switch takes place. We thus introduce the concept of user-controlled service handover to conceptualize how a user could transfer a session (e.g., a telephone conversion) from one media to another. The model consists of two levels:

•On the infrastructure level, the model follows the automatic view of sessionmanagementbyestablishingtheunderlyingcommunication(e.g., authentication, handshaking, and so on) across the different platforms automatically as soon as the devices are within range of each other.

•To enable sustained car conversations, we introduce the concept of usercontrolled service hand over as the process by which a user transfers a session in its current state to another media resource. Here, redundancy across media might be required to ensure that the user misses nothing of importance when shifting from one platform to another.

Requirements for Sustained Car Conversations

Applyingtheuser-controlledsessionmanagementmodel,thefollowingdesign requirements can be determined for car conversation systems:

•Support user-controlled service hand over between phone resources.

•Support automatic transfer of sessions on the infrastructure level.

•Support redundancy across platforms. (In situations where users switch media during an ongoing activity, redundancy helps in ensuring that users have full control.)

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The next section describes the design of a car conversation system prototype called SeamlessTalk, which implements the proposed user-controlled session managementmodel.

Implementation of SeamlessTalk

Application

SeamlessTalk is an in-car mobile phone hands-free system intended to manage sustained car conversations. The prototype system was developed as a component of the infotainment system of the new Saab 9-3 car (see Figure 1 and Figure 2).

SeamlessTalk consists of four main components (see Figure 3): A Bluetooth enabled mobile phone, an in-car phone resource system, a service layer, and an infrastructure layer.

First, the system requires a Bluetooth equipped mobile phone. In its current version, the system supports the Nokia 6310i and Nokia 6550 (a 3G terminal). Second, the system includes an in-car phone resource system intended to provide the resources needed for enhancing the convenience and safety of car conversations. It consists of four components: dashboard control buttons, a 5.8

Figure 1. The dashboard of a Saab 9-3 equipped with the infotainment system

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312 Henfridsson, Wiberg, Lindgren & Ljungberg

Figure 2. The main menu of the infotainment system

Figure 3. The components of SeamlessTalk

Service layer

33..

Infrastructure layer

44..

inches screen integrated in the dashboard, a microphone, and an in-car audio system. Third, the system comprises a service layer that defines the session management considerations. This layer handles establishment of phone calls, maintenance of running sessions, handover of calls between the phone and the in-car resources, and termination of sessions. Fourth, the system comprises an infrastructure layer. This layer makes it possible for the different components of SeamlessTalk to communicate and co-exist. One important component of this layer is the Bluetooth access point provided by the car’s infotainment

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system. This access point is necessary to establish ad hoc connections to paired mobile phones. The prototype uses the standard Bluetooth ad hoc networking protocol with the service discovery protocol and the hands-free profile.

SeamlessTalk in Use

With the SeamlessTalk functionality, the driver can manage car conversations inthefollowingway:

While seated in the car, the driver can initiate a call by either using the dial pad on the dashboard or the address book stored in the infotainment system. The mobile phone sets up the outgoing call and initiates the audio connection between the mobile phone and the in-car audio system. In the case of entering thecarwithanongoingcallonthemobilephone,thedriverselectsthetelephone option from the main menu of the infotainment system and then uses the handsfree option (see Figure 4) to establish an audio connection between the mobile phone and the in-car audio system. The ongoing call can then be terminated from the infotainment system or from the mobile phone. When leaving the car with an ongoing call or for privacy reasons, the audio output can be transferred from the in-car audio system to the mobile phone by selecting the “transfer to mobile” option of the infotainment system (see Figure 5).

Figure 4. Audio output of the call can be transferred from the mobile phone brought into the car to the in-car audio system

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