MMUSIC Working Group Daisaku Komiya Internet Draft Xu Mingqiang Expires: August 26, 2006 Eunsoo Shim Panasonic February 27 2006 Use Cases for Session Mobility in Multimedia Applications draft-komiya-mmusic-session-mobility-usecases-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on 26 August, 2006 Copyright Notice Copyright (C) The Internet Society (2006). All Rights Reserved. Abstract Session mobility allows a user to transfer an ongoing session from one device to another device. This document attempts to summarize the use cases for session mobility in multimedia applications. For each use case, we provide possible motivation for the user to initiate a session transfer from one device to another. draft-komiya-mmusic-session-mobility-usecases-00.txt komiya Expires August, 2006 [Page 1] Use Case for Session Mobility February 2006 Table of Contents 1.Introduction...................................................2 2 Terminology....................................................3 3.Use Cases......................................................3 3.1 Transferring a whole session from one device to another device...............................................3 3.2 Transferring a whole session from one device to multiple devices..............................................6 3.3 Transfer with the Split of Audio and Video..............7 4. IANA Considerations...........................................8 5. Security Considerations.......................................8 6. References....................................................8 7. Acknowledgements..............................................9 8. Author's Addresses............................................9 1.Introduction IP-based multimedia streaming applications like VoD (Video on Demand) and real-time applications like interactive video games, video-conferencing and video surveillance are important current or potential usages of mobile devices. Mobile devices provide convenience of mobility but have limited capability compared to stationary devices; for example, smaller screens and computing power than stationary devices. Proliferation of IP-based multimedia capable devices and increasingly ubiquitous wireless access would create more opportunities for interaction among devices, both static and mobile. For maintaining the continuity of a user's multimedia experience, it is expected that the service in mobile device is transferred to another device in some situations, such as, that the battery is almost discharged, or, user wants to use a target device with a big display and/or a more suitable network(Factors like bandwidth, cost, etc). On the other hand, when a user leaves home or office, she may need to transfer a service received by a stationary devices to her mobile device. Session mobility allows a user to transfer an ongoing session from one device to another device. The general approach to achieve session mobility by SIP [1] including the discovery process to locate transfer target devices and signaling procedures has been described in [6]. 3GPP also proposed komiya Expires August 2006 [Page 2] Use Cases for Session Mobility February 2006 session mobility as a part of the vision of 3GPP All-IP networks [7]. The above documents [6][7] have not presented use case scenarios in detail. The purpose of this document is to describe and classify use cases for session mobility in the context of multimedia applications. 2 Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC 2119]. Device: A software or hardware appliance, which is represented by a SIP UA. Session: A session is a set of senders and receivers and the data stream flowing from senders to receivers, or, logically the linked sending/receiving of data/control stream between the sender and receiver. A multimedia conference is an example of a session. Session Mobility: The ability for a communication session to be moved from one device to another under the control of the user. Session Transfer: The act of moving a communication session from one device to another under the control of the user. 3. Use Cases The use cases listed up in this section are applied in the IP-based network environments. Currently, WLAN-based IP mobile phones are already being used in some environments. IP-based wide-area mobile communications services are expected to be deployed using a technology like WiMax. Furthermore, the cellular industry is moving toward the all-IP network architecture[7]. The following use cases will be supported by such emerging IP-based wireless communications technologies. 3.1 Transferring a whole session from one device to another device First we deal with technically simpler cases - a session transfer from a device to another device, and describe use cases classified according to the reason or motivation by which a user may want to invoke a session transfer. Some scenarios may be related to multiple reasons. komiya Expires August 2006 [Page 3] Use Cases for Session Mobility February 2006 3.1.1 Achieving user mobility A user can avoid a loss of a session by transferring the session to a mobile device when the user moves away from the current device that is fixed. A user, while driving, is listening to a music concert streamed over the wireless Internet from an audio on demand service. She is using an Internet radio device embedded in the dash board of the car. After parking the car, she leaves the car for her home. Not wanting to miss any part of the concert, she transfers the streaming session from the vehicular Internet radio to her cell phone that is capable of connecting to the Internet audio streaming service. Another scenario is as follows. A user is watching a live Cricket match on her IP-TV at home, but has to leave for work. She simply pushes a button on her mobile and transfers the live match from the TV to her mobile without missing a shot. Thus, allowing her to seamlessly experience multimedia content without affecting her mobility. Session transfer between fixed devices can be used to serve mobile users, as well. For example, a user is watching a cricket match on a TV in her living room. The sensors in her home track her location using the mobile as reference. When the user moves from the living room to a study-room, the session is transferred from the TV in the living room to a TV in the study-room based on her location. Thus the user can watch the game continuously. 3.1.2 Achieving better user perception of service A user, in her office, receives a call on her cell phone. Unfortunately the signal reception of the cell phone is not good and thus the voice quality is poor. Instead of hanging up the phone and calling back the other person, the user simply transfers the call from the cell phone to a desktop VoIP phone in her office. The desktop VoIP phone is wired to the office LAN that has a broadband connection to the Internet, thus, the voice quality is better. Another example scenario is as follows. A user finds an interesting movie broadcasted over the wireless Internet while browsing the Internet streaming services on her mobile phone in the backyard of her house. The user enters the house's living room in which there is a plasma TV with a big screen. The user sits on the sofa, turns on the TV, and transfers the movie to the TV. Now the video and audio qualities get much better as the video and audio stream komiya Expires August 2006 [Page 4] Use Cases for Session Mobility February 2006 characteristics are adjusted for playback on the TV, taking advantage of the larger bandwidth, screen and superior audio capability available with the TV. One more scenario is as follows. A user is using a PDA to see a live soccer game broadcasted over wireless internet while walking into her house. After he enters her room, she wants to free hand without holding the PDA, so she moves to the TV, then pushes a button on the PDA to transfer the service to the TV. It is transferred immediately, she does not miss the scene of shoot happened at that moment. Thus, she is not only able to leverage larger display and resources of the TV but also utilize the broad- band internet connection if available. 3.1.3 Avoiding a loss of the current session because of resource shortage A user can avoid a loss of a session by transferring the session to a new device when her current device cannot support the current session any longer because of resource shortage. A user, in her office, receives a call from an important customer on her cell phone. During the video conference call, she finds that her cell phone's battery is almost completely discharged. It is a critical conversation for her business and thus she must continue it without any disruption. So instead of asking her customer to hang up the call and resume, she transfers the call to her desktop phone by pushing the button on her cell phone. During the transfer, without any media skipping or overlapping, the customer does not know the user on a different phone. 3.1.4 Lowering the communication cost Typically communications services over a cellular network are more expensive than similar services over a wired network/unlicensed wireless network (WLAN, etc)/enterprise networks. So if a call is transferred from a cellular phone to a desktop phone, it is likely that the user lowers the communication cost. For example, when a user receives a call on her cell phone in the office, the user transfers the call to the desktop phone in the office without asking the caller to do anything. Such a session transfer is much more acceptable and convenient than asking the caller to hang up and wait for a callback. In the above scenarios, the ongoing session established between current device and corresponding node/media server is transferred to a new device, which is depicted in figure 1. In figure 1, the komiya Expires August 2006 [Page 5] Use Cases for Session Mobility February 2006 current device and the new device connect with the different access networks, whereas these two devices can also belong to the same access network. +-----------------------+ | Correspondent Node | +-----------------------+ | +----------------------------------------+ | Internet | +----------------------------------------+ | | +--------------------+ +----------------------+ | Access Network 1 | | Access Network 2 | +--------------------+ +----------------------+ | | +-----------------+ +--------------+ | Current Device | ------> | New Device | +-----------------+ +--------------+ Figure 1 One-to-one session transfer 3.2 Transferring a whole session from one device to multiple devices While motivated with the same four reasons, a user or a group of users may invoke session transfers that involve more than two devices. Here is an example scenario. A couple is accessing a live music concert by a PDA while taking a car. After parking, they walk into their house, both of them want to watch this service continuously, but the wife wants to go to kitchen for preparing a meal whereas her husband wants to go to his study-room for checking email. So she pushes a button on her PDA to transfer the streaming service to TV in kitchen and PC in study room. +----------------+ | Media Server | +----------------+ | +-------------------------------------------+ | Internet | +-------------------------------------------+ | | | komiya Expires August 2006 [Page 6] Use Cases for Session Mobility February 2006 +------------+ +----------+ +----------+ | Access | | Access | | Access | | Network 1 | | Network 2| | Network 3| +------------+ +----------+ +----------+ | | | +-------+ +-----+ | | | ------> | PC | | | PDA | +-----+ | | | +-------+ | | ------------------- > | TV | +-------+ +-------+ Figure 2 One to multiple devices Please note that this scenario can be realized as a session fork and a session transfer. That is, while the session is on the TV, a replicated session is forked on the PDA. After that, the session on the TV is transferred to the mobile phone. 3.3 Transfer with the Split of Audio and Video A user may want to transfer a media stream or a subset of streams in a session from a device to different devices. Here is an example scenario. A user is playing an interactive game on her mobile device over a WLAN in the house. The user wants to play it on a big TV screen. But the TV is in a room where a family member is working on a computer. The user does not want to bother the family member by the sound of the game. So the user just transfers the video stream to the TV, keeps the audio stream on the mobile device. +----------------------+ | Media Server | +----------------------+ | +------------------------------------------+ | Internet | +------------------------------------------+ | | +-------------------+ +-------------------+ | Access Network 1 | | Access Network 2 | +-------------------+ +-------------------+ | | Audio | |Video | | +-------------+ +-----+ |Mobile Device| --> | TV | +-------------+ +-----+ Figure 3 Transfer with the split of Audio and Video komiya Expires August 2006 [Page 7] Use Cases for Session Mobility February 2006 Another scenario is transferring the audio and the video streams to two different devices separately. For example, a user starts a video conference call by her mobile phone in an office. During the conference, it becomes necessary to invite other project members to the video conference. She moves to a conference room and transfers the audio stream to a speaker system and the video stream to a projector. +----------------+ | Media Server | +----------------+ | +----------------------------------+ | Internet | +----------------------------------+ | | | +-----------+ +-----------+ +-----------+ | Access | | Access | | Access | | Network 1 | | Network 2 | | Network 3 | +-----------+ +-----------+ +-----------+ | Audio | | +-------+ +------------+ |Video | |----> | Speaker | | | Mobile| +------------+ | | Phone | +-----------+ | | ---------------- > | Projector | +-------+ +-----------+ Figure 4 Transfer to multiple devices with media split 4. IANA Considerations There is no need for IANA consideration from the current version of this document. 5. Security Considerations Many security concerns must be addressed in the above uase cases. Some of the security concerns are already addressed in [6] 6. References [1] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., komiya Expires August 2006 [Page 8] Use Cases for Session Mobility February 2006 Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [2] Bradner, S., "Key words for use in RFCs to Indicate Requirements Levels", RFC 2119, March 1997. [3] Handley, H. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [4] Handley, H., "The Session Initiation Protocol (SIP) REFER Method", RFC 3515, April 2003. [5] Wenger, S., Hannuksela, M., Westerlund, T., and D. Singer, "RTP Payload Format for H.264 Video", RFC 3984, February 2005. [6] Shacham, R., Schulzrinne, H., Thakolsri, S., and W. Kellerer, "Session Initiation Protocol (SIP) Session Mobility", draft-shacham-sipping-session-mobility-01 (work in progress),July 2005. [7] Sancho, ed., "All-IP Network (AIPN) Feasibility Study, Release7", 3GPP TR22.978, 2005. 7. Acknowledgements We thankfully acknowledge the help of Sujeet Mate and Umesh Chandra of Nokia, who contributed use case suggestions and ideas to this draft. We also would like to thank Brijesh Kumar of PDNL for his many useful suggestions to improve the contents of this draft. 8. Author's Addresses Daisaku Komiya Matsushita Electric Industrial Co., Ltd.(Panasonic) 4-12-4 Higashi-shinagawa Shinagawa-ku, Tokyo Japan Email: komiya.daisaku@jp.panasonic.com Xu Mingqiang Matsushita Electric Industrial Co., Ltd.(Panasonic) 4-12-4 Higashi-shinagawa Shinagawa-ku, Tokyo Japan Email: xu.mingqiang@jp.panasonic.com komiya Expires August 2006 [Page 9] Use Cases for Session Mobility February 2006 Eunsoo Shim Panasonic Digital Networking Laboratory Two Research Way, 3rd Floor Princeton, NJ 08540 USA Email: eunsoo@research.panasonic.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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