Usability Assessment Of Usb-Type Iptv Remote Controller For People With Limited Hand Functions

Shinyoung Lim1, Jongbae Kim1, Jeonghyun Kim1, Heesook Lee1, Myoungjoon Lim1, Kyongnim Lee2, Youngju Do2, Jinhan Kim2

1National Rehabilitation Research Institute, Seoul, Korea

2R&D Laboratory, KT Corporation, Seoul, Korea


As we are experiencing new media era, there is growing issues on accessibility and usability of new media for people with limited hand functions. One of new media with fast growing number of subscribers is IPTV service. However, most television remote controllers have number of tiny buttons providing different kinds of IPTV features that limit people with limited hand functions to access IPTV media. KT Corporation develops a user interface bridging a user’s mouse and USB-type IPTV remote controller. To assess usability of the KT’s user interface, National Rehabilitation Research Institute (NRRI) designs and tentatively assesses its usability. NRRI delivers initial recommendations to KT Corporation to update the KT’s IPTV remote controller to enhance the usability, which focusing on enhancement of effectiveness, productivity, and satisfaction of the IPTV user interface. A few findings are discussed to enhance usability of the IPTV user interface and to bring number of further research topics.

KT iptv and user interface

KT Corporation is recognized as one of major providers of IPTV service with more than seven million subscribers in South Korea. KT’s IPTV service provides clients with new media service such as real-time two-way digital television channels, Video-on-Demand (VoD) service with more than 170 thousands media contents, and terrestrial digital multimedia broadcasting in the area of South Korean peninsula. To meet the IPTV usability and accessibility needs of people with limited hand functions, KT R&D Laboratory designs and implements a IPTV user interface consists of a USB-type IPTV remote controller communicating with assistive devices, such as Integra mouse and big-ball mouse, for wheelchair users. The KT’s IPTV user interface provides basic IPTV controlling features, i.e., power on/off, volume/channel controls, VoD play/control and home portal menu navigations.

fillerFigure 1: Usability Assessment setting in a NRRI Testbed

With three kinds of mouse pressing modes, i.e., short, long, and double click, and pressing right and left mouse buttons, KT defines combinational buttons those are one-to-one mapped with mouse events to IPTV features. These combinational buttons provide IPTV subscribers with single button operations of the currently available IPTV remote controller. These single button operations are set-top box (STB) mode (on/off), volume mode (up/down), channel mode (up/down), home portal menu, movement mode (up-down-right-left), and Video-on-Demand (VoD) mode (play, pause, stop, fast forward (FF), rewind, and exit). The USB-type IPTV remote controller is able to communicate with any type of mouse, i.e., trackball mouse, foot mouse, and Integra mouse. Figure 1 shows the usability assessment setting in a NRRI testbed.

assessment design

NRRI designs the usability assessment adopted from ISO standards on software usability testing focusing on effectiveness, productivity, satisfaction, and safety perspectives of products, i.e., assistive devices, to meet needs of independent living and social inclusion of the people with disability (Abran, 2003; Maguire, 2001). NRRI recruits four subjects with limited hand functions from SCI C4-5, SCI C5-6, Muscular Dystrophy (MD) and Cerebral Palsy (CP), respectively. Each subject is member of NRRI’s Focus Group and represents their disability groups. The location where the usability assessment processed is in a NRRI Testbed designed for two purposes: Short term (up to two weeks) in-home stay for social inclusion readiness and real home testing space for usability assessment of assistive devices and quality of life technology for people with disability. This testbed provides subjects with safe and secure, and even with feeling like they are at home in case of participating usability assessments. NRRI implements two portable CCTV devices those are available at the testbed during the usability assessment time. Other devices for usability assessment such as a CCTV controller, a video analyzer system, and one pair of wireless radio are located in the next room of the testbed where the client of the usability assessment, i.e., KT Corporation, is allowed to participate noninvasively. To assess clearly and avoid conflict of interest, NRRI adopts blind assessment such as not allowing any type of communications between subjects and clients before, during, and after of the assessment for certain amount of time.

The design of the usability assessment protocol consists of series of process starting from subject’s consent after explaining the usability assessment, medical checkup with disability assessment of the subject, preliminary survey focusing on new media needs and issues (seven questions), tutoring the KT IPTV user interface, monitoring and measuring effectiveness and satisfaction of IPTV service scenario by the subject (24 steps), in-depth survey focusing on feedback and comments of overall IPTV service (seven questions), quantitative and qualitative analysis of assessment data, and finally extracting meaningful findings and recommendations among the analyzed data (Bevan, 2009; Douglas, 1999).


Preliminary Survey

Subjects have experience of using different types of mouse, such as headset mouse, pad mouse, trackball mouse, foot mouse, and Integra mouse to access information services.

Subject with SCI C4-5 has experience of IPTV subscription for two years with assistance from family members or caregivers when he watches the IPTV at home.

Subject with SCI C5-6 usually uses his back of the hand to press the IPTV remote controller buttons but it does not productive and often causes false button press.

Subject with MD has experience of cable TV subscription with traditional remote controller but he has operational issues on the remote controller as well as pressing double clicks of his traditional mouse. As he is at the minor stage of his MD, he usually uses traditional remote controller and mouse but it is getting difficult to control them precisely and he will need track ball mouse or other accessible mouse in the very near future.

Subject with CP subscribes digital TV, not IPTV, with a traditional remote controller. He also uses a traditional PC mouse but he has issues on using the remote controller and the mouse because of his spasticity and left-handed.

IPTV Service Scenario (24 steps)

The IPTV service scenario consists of six phases with 24 steps that is able to assess all available features of the IPTV remote controller such as changing mode (home portal mode, volume mode, channel mode), power mode (power on/off), channel mode (changing channels), volume mode (changing volume), home portal control mode (home portal services), and Video-on-Demand (VoD) control mode (home portal VoD services).

The service scenario is designed in type of step-by-step process of assessing each features of the IPTV remote controller. As the subject is new to the IPTV remote controller, an occupational therapist assists the subject in using the IPTV remote controller features. It takes about 40 to 45 minutes in average covering the tutorial and the IPTV service scenario.


fillerFigure 2: Snap shots of usability assessment

After subjects are experiencing these 24 steps in their tutorial session, subjects are asked to perform each feature and to answer questions on effectiveness and satisfaction of each feature. The occupational therapist monitors and assesses dexterity and response times from subject side (mouse operation) as well as the USB-type IPTV remote controller side (interface and system operations). Figure 2 shows snap shots of each subject’s participation of the usability assessment.

In-depth Survey

Subject with SCI C-4-5 responses with satisfaction even though a few more button presses required than that of his home remote controller might be negative feedbacks. More learning time required of the IPTV remote controller is the only negative comment from him.

Subject with SCI C5-6 mentions a few more pressings on the mouse button might cause difficulty in hand functions. He feels pain in frequent pressing the mouse button during the IPTV service scenario session.

Subject with MD reacts with positive feedbacks because he feels using the mouse user interface is much easier than using traditional remote controllers due to their tiny buttons.

Subject with CP points out that using mouse will be valuable to the people with severe CP and the mouse needs to be attached on the table as people with CP often experiencing spasticity.


Quantitative findings

Table 1 describes quantitative findings from each subject in preliminary session, IPTV service scenario session, and in-depth survey session of the usability assessment protocol for the KT IPTV user interface.

Table 1: Quantitative findings of usability assessment (KT IPTV user interface)


Quantitative Findings (100% scale)

Preliminary Survey

(Product expectation (A) and Understanding tutorial (B))

IPTV service Scenario

(Effectiveness  C)  and Satisfaction (D) of the product)

In-depth survey

(Self-learning capability (E) and Overall product satisfaction (F))








Subject-1 (SCI C4-5)







Subject-2 (SCI C5-6)























We find an interesting pattern of error in IPTV service scenario session which is an error in exiting channel change mode.

Subject with MD mentions that increase number of pressing buttons, long press, and double clicks are challenges due to his lack of muscle power.

Subject with CP also suggests the mouse needs to be attached on the tray or wheelchair while using the mouse to control the IPTV because of his spasticity.

Qualitative findings

A few issues might be resolved with the KT IPTV user interface which are difficulties in surfing IPTV menu options, setting schedule for IPTV program recording and replaying, and changing menu of channel-home portal-volume that causes re-do from the start. However, most subjects suggest adopting voice recognition technology for IPTV remote controller due to their mobility issues.

An increase number of mouse operations, long press, and double clicks in using the KT IPTV user interface are found as one of common issues of the KT product. KT needs to develop algorithms to reduce number of mouse operations for the wheelchair users, in general. Subject with SCI C5-6 also hopes to use a wheel on his track ball mouse in changing IPTV volume, feature settings, and channels.


Review the usability assessment protocol

With the preliminary usability assessment of KT IPTV user interface, we need to review the design factors of the usability assessment protocol from the prospective users’ perspective. Most of all, we need to in line with the purpose of the usability assessment which is to search for some clue to suggest or recommend client, i.e., KT, to enhance usability of the product being developed. We also need to consider measurement elements of the usability assessment which are effectiveness, productivity, satisfaction, and safety of the product for the people with disability. This framework is adopted from ISO standards on software usability and Common Industry Format (Bevan, 2002).

The assessment criteria and goals of the KT IPTV user interface need to be focused on subject’s limited hand functions and assistive features to resolve these limitations. A table of one-to-one mapping on limitations and assistive features might be helpful to design the delivery of initial recommendations from the data of the usability assessment protocol.

Initial recommendations

To enhance usability of the KT IPTV user interface, numbers of recommendations are collected from the results and findings of the usability assessment.

A similar pattern of error which is ‘exiting channel change mode’ needs to find resolution to avoid or bypass this error.

We find that increase number of pressing buttons, long press, and double clicks are common challenges to people with limited hand functions.

A few issues of surfing IPTV menu options, setting schedule of IPTV program recording and replaying, and changing menu of channel-home portal-volume might be common issues to all IPTV subscribers. We need to find correlations between the subject’s operational limits of IPTV remote controller and features of the KT IPTV user interface.

Adopting voice recognition technology into IPTV remote controller due to the subject’s limited hand function issues might be the ultimate resolution. However, the location and user interface as well as recognition ratio of the voice recognition to be used for the IPTV remote controller should be resolved before adopting the technology. When the IPTV volume is high, the user might find difficulty in accessing the IPTV remote controller with his voice commands due to the high TV volume. Noise generated from the Activities of Daily Living (ADL) or natural noise might be one of barriers to adopt the voice recognition technology into the IPTV remote controller (Ahn, 2011; Hone, 2001).


Efforts on enhancing usability of user interface of the KT’s USB-type IPTV remote controller be hopefully guide ideas and directions to other related development activities of user interfaces and assistive technology for people with disability.

Along with usability assessment, accessibility assessment of new media might be going simultaneously to merge ideas, i.e., suggestions and recommendations together to enhance usability and accessibility of the products being developed. This direction will ultimately provide users with highly acceptable assistive devices and quality of life technology in their independent daily living and eventually, social inclusion.

With a few findings from the usability assessment, NRRI will be able to submit number of recommendations to the KT research team those will enhance usability of the product for the prospective users. A number of research topics will be discussed on the RESNA floor but not limited to finding correlations between the limitations and available features of the IPTV, and verification of applying usability protocol to assistive technologies for people with disability.


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This work was supported by the Technology Innovation Program (100036459, Development of center to support QoLT industry and infrastructures) funded by the MKE/KEIT, Korea.

Author contact information

Shinyoung Lim, PhD.
National Rehabilitation Center Research Institute
111 Gaorigil, Gangbuk-gu, Seoul, Korea, 142-884, Office Phone (82-2) 901-1978 FAX: (82-2) 901-1972

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